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  • Inorganic Chemistry  (3,613)
  • Fluid Mechanics and Thermodynamics
  • 1990-1994  (3,724)
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Years
Year
  • 1
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    Oscillatory Dynamics of Single Bubbles and Agglomeration in a Sound Field in Microgravity (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: A dual-frequency acoustic levitator containing water was developed for studying bubble and drop dynamics in low gravity. It was flown on USML-1 where it was used in the Glovebox facility. High frequency (21 or 63 kHz) ultrasonic waves were modulated by low frequencies to excite shape oscillations on bubbles and oil drops ultrasonically trapped in the water. Bubble diameters were typically close to 1 cm or larger. When such large bubbles are acoustically trapped on the Earth, the acoustic radiation pressure needed to overcome buoyancy tends to shift the natural frequency for quadrupole (n = 2) oscillations above the prediction of Lamb's equation. In low gravity, a much weaker trapping force was used and measurements of n = 2 and 3 mode frequencies were closer to the ideal case. Other video observations in low gravity include: (i) the transient reappearance of a bulge where a small bubble has coalesced with a large one, (ii) observations of the dynamics of bubbles coated by oil indicating that shape oscillations can shift a coated bubble away from the oil-water interface of the coating giving a centering of the core, and (iii) the agglomeration of bubbles induced by the sound field.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, Volume 2; 673-690; NASA-CP-3272-Vol-2
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  • 2
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    Crossflow-Vortex Breakdown on Swept Wings: Correlation of Nonlinear Physics (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The spatial evolution of cross flow-vortex packets in a laminar boundary layer on a swept wing are computed by the direct numerical simulation of the incompressible Navier- Stokes equations. A wall-normal velocity distribution of steady suction and blowing at the wing surface is used to generate a strip of equally spaced and periodic disturbances along the span. Three simulations are conducted to study the effect of initial amplitude on the disturbance evolution, to determine the role of traveling cross ow modes in transition, and to devise a correlation function to guide theories of transition prediction. In each simulation, the vortex packets first enter a chordwise region of linear independent growth, then, the individual packets coalesce downstream and interact with adjacent packets, and, finally, the vortex packets nonlinearly interact to generate inflectional velocity profiles. As the initial amplitude of the disturbance is increased, the length of the evolution to breakdown decreases. For this pressure gradient, stationary modes dominate the disturbance evolution. A two-coeffcient function was devised to correlate the simulation results. The coefficients, combined with a single simulation result, provide sufficient information to generate the evolution pattern for disturbances of any initial amplitude.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 3
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    Assessing the Capability of Doppler Global Velocimetry To Measure Vortical Flow Fields (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: A new nonintrusive flow diagnostics instrumentation system, Doppler global velocimetry, is presented. The system is capable of making simultaneous, three-component velocity measurements within a selected measurement plane at video camera rates. These velocity images can provide the researcher with spatial and temporal information about the flow field in a global sense. The investigation of a vortical flow above a 75-degree delta wing comparing standard three-component, fringe-type laser velocimetry measurements with Doppler global velocimetry measurements is presented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Journal of Aerospace Engineering; Volume 208; Part G; 99-105
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  • 4
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    An Implicit Upwind Algorithm for Computing Turbulent Flows on Unstructured Grids (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: An implicit, Navier-Stokes solution algorithm is presented for the computation of turbulent flow on unstructured grids. The inviscid fluxes are computed using an upwind algorithm and the solution is advanced in time using a backward-Euler time-stepping scheme. At each time step, the linear system of equations is approximately solved with a point-implicit relaxation scheme. This methodology provides a viable and robust algorithm for computing turbulent flows on unstructured meshes. Results are shown for subsonic flow over a NACA 0012 airfoil and for transonic flow over a RAE 2822 airfoil exhibiting a strong upper-surface shock. In addition, results are shown for 3 element and 4 element airfoil configurations. For the calculations, two one equation turbulence models are utilized. For the NACA 0012 airfoil, a pressure distribution and force data are compared with other computational results as well as with experiment. Comparisons of computed pressure distributions and velocity profiles with experimental data are shown for the RAE airfoil and for the 3 element configuration. For the 4 element case, comparisons of surface pressure distributions with experiment are made. In general, the agreement between the computations and the experiment is good.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Computers Fluids; Volume 23; No. 1; 1-21
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  • 5
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    Triangulation of NURBS Surfaces (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: A technique is presented for triangulation of NURBS surfaces. This technique is built upon an advancing front technique combined with grid point projection. This combined approach has been successfully implemented for structured and unstructured grids.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 6
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    Oscillatory Thermocapillary Flow Experiment (OTFE) (1994)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: An experiment was performed on oscillatory thermocapillary flow in the Glovebox aboard the USML-1 Spacelab which was launched in July, 1992. Cylindrical containers of 1 and 3 em in diameter were used. Silicone oils of 2 and 5 cSt viscosity were the test fluids. The fluid was heated by a cylindrical heater placed along the centerline of the container. The diameter of the heater was 10% of the container diameter. The fluid motion was studied by flow visualization. Although oscillations were observed briefly, bubbles generated in the fluid during the experiment disturbed the flow substantially so that the critical temperature differences could not be determined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, Volume 2; 701-715; NASA-CP-3272-Vol-2
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  • 7
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    Applied Computational Fluid Dynamics at NASA Ames Research Center (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: The field of Computational Fluid Dynamics (CFD) has advanced to the point where it can now be used for many applications in fluid mechanics research and aerospace vehicle design. A few applications being explored at NASA Ames Research Center will be presented and discussed. The examples presented will range in speed from hypersonic to low speed incompressible flow applications. Most of the results will be from numerical solutions of the Navier-Stokes or Euler equations in three space dimensions for general geometry applications. Computational results will be used to highlight the presentation as appropriate. Advances in computational facilities including those associated with NASA's CAS (Computational Aerosciences) Project of the Federal HPCC (High Performance Computing and Communications) Program will be discussed. Finally, opportunities for future research will be presented and discussed. All material will be taken from non-sensitive, previously-published and widely-disseminated work.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Oct 28, 1994; AZ; United States
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  • 8
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    Visualizing Flow Over Parametric Surfaces Using Line Integral Convolution (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Line Integral Convolution (LIC) is a powerful technique for imaging and animating vector fields. We extend the LIC paradigm in three ways: (1) The existing technique is limited to vector fields over a regular Cartesian grid. We extend it to vector fields over parametric surfaces, such as those found in curvilinear grids, used in computational fluid dynamics simulations; (2) Periodic motion filters can be used to animate the flow visualization. When the flow lies on a parametric surface, however, the motion appears misleading. We explain why this problem arises and show how to adjust the LIC algorithm to handle it; (3) We introduce a technique to visualize vector magnitudes as well as vector direction. Cabral and Leedom have suggested a method for variable-speed animation, which is based on varying the frequency of the filter function. We develop a different technique based on kernel phase shifts which we have found to show substantially better results. Our implementation of these algorithms utilizes texture-mapping hardware to run in real time, which allows them to be included in interactive applications.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Visualization 1994; Oct 17, 1994 - Oct 21, 1994; Washington, DC; United States
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  • 9
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    Calibration of Axisymmetric and Quasi-1D Solvers for High Enthalpy Nozzles (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: The proposed paper will present a numerical investigation of the flow characteristics and boundary layer development in the nozzles of high enthalpy shock tunnel facilities used for hypersonic propulsion testing. The computed flow will be validated against existing experimental data. Pitot pressure data obtained at the entrance of the test cabin will be used to validate the numerical simulations. It is necessary to accurately model the facility nozzles in order to characterize the test article flow conditions. Initially the axisymmetric nozzle flow will be computed using a Navier Stokes solver for a range of reservoir conditions. The calculated solutions will be compared and calibrated against available experimental data from the DLR HEG piston-driven shock tunnel and the 16-inch shock tunnel at NASA Ames Research Center. The Reynolds number is assumed to be high enough at the throat that the boundary layer flow is assumed turbulent at this point downstream. The real gas affects will be examined. In high Mach number facilities the boundary layer is thick. Attempts will be made to correlate the boundary layer displacement thickness. The displacement thickness correlation will be used to calibrate the quasi-1D codes NENZF and LSENS in order to provide fast and efficient tools of characterizing the facility nozzles. The calibrated quasi-1D codes will be implemented to study the effects of chemistry and the flow condition variations at the test section due to small variations in the driver gas conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 29th AIAA Thermophysics Conference; Jun 19, 1995 - Jun 22, 1995; San Diego, CA; United States
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  • 10
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    Scientific Visualization of Large Scale Unsteady Fluid Flow (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: In a numerical flow simulation. it is common to generate several thousand time steps of unsteady (time-dependent) flow data. Each time step may require tens to hundreds of megabytes for disk storage, and the total disk requirement for storing the unsteady flow data may be hundreds of gigabytes. Interactive visualization of unsteady flow data of this magnitude is presently impossible with the current hardware technology. This chapter describes the current approaches for unsteady flow visualization. An effective particle tracing technique for unsteady flow is also described. First, the life cycle of a typical numerical flow simulation is outlined. Several unsteady flow data sets from real-world problems are then given. The current approaches for visualizing unsteady flow are then described. There are many existing systems for flow visualization, and some of them are discussed. Streaklines depict time-varying phenomena that are sometimes difficult or impossible to see with other visualization techniques. The algorithms for computing streaklines are described. Several unsteady flow data sets have been visualized using streaklines, and the results are presented. Finally, some current issues in unsteady flow visualization are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 11
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    A Navier-Strokes Chimera Code on the Connection Machine CM-5: Design and Performance (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: We have implemented a three-dimensional compressible Navier-Stokes code on the Connection Machine CM-5. The code is set up for implicit time-stepping on single or multiple structured grids. For multiple grids and geometrically complex problems, we follow the 'chimera' approach, where flow data on one zone is interpolated onto another in the region of overlap. We will describe our design philosophy and give some timing results for the current code. A parallel machine like the CM-5 is well-suited for finite-difference methods on structured grids. The regular pattern of connections of a structured mesh maps well onto the architecture of the machine. So the first design choice, finite differences on a structured mesh, is natural. We use centered differences in space, with added artificial dissipation terms. When numerically solving the Navier-Stokes equations, there are liable to be some mesh cells near a solid body that are small in at least one direction. This mesh cell geometry can impose a very severe CFL (Courant-Friedrichs-Lewy) condition on the time step for explicit time-stepping methods. Thus, though explicit time-stepping is well-suited to the architecture of the machine, we have adopted implicit time-stepping. We have further taken the approximate factorization approach. This creates the need to solve large banded linear systems and creates the first possible barrier to an efficient algorithm. To overcome this first possible barrier we have considered two options. The first is just to solve the banded linear systems with data spread over the whole machine, using whatever fast method is available. This option is adequate for solving scalar tridiagonal systems, but for scalar pentadiagonal or block tridiagonal systems it is somewhat slower than desired. The second option is to 'transpose' the flow and geometry variables as part of the time-stepping process: Start with x-lines of data in-processor. Form explicit terms in x, then transpose so y-lines of data are in-processor. Form explicit terms in y, then transpose so z-lines are in processor. Form explicit terms in z, then solve linear systems in the z-direction. Transpose to the y-direction, then solve linear systems in the y-direction. Finally transpose to the x direction and solve linear systems in the x-direction. This strategy avoids inter-processor communication when differencing and solving linear systems, but requires a large amount of communication when doing the transposes. The transpose method is more efficient than the non-transpose strategy when dealing with scalar pentadiagonal or block tridiagonal systems. For handling geometrically complex problems the chimera strategy was adopted. For multiple zone cases we compute on each zone sequentially (using the whole parallel machine), then send the chimera interpolation data to a distributed data structure (array) laid out over the whole machine. This information transfer implies an irregular communication pattern, and is the second possible barrier to an efficient algorithm. We have implemented these ideas on the CM-5 using CMF (Connection Machine Fortran), a data parallel language which combines elements of Fortran 90 and certain extensions, and which bears a strong similarity to High Performance Fortran. We make use of the Connection Machine Scientific Software Library (CMSSL) for the linear solver and array transpose operations.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 2nd Overset Composite Grid and Solution Technology Symposium; Oct 25, 1994 - Oct 28, 1994; Fort Walton Beach, FL; United States
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  • 12
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    Progress In Incompressible Pump Flow Calculations (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: Steady and unsteady flows for propulsion systems are efficiently simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudo compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. Current computations use one equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard kappa - epsilon model equations. The resulting computer code is applied to the flow analysis inside an advanced rocket pump impeller in steadily rotating reference frames. Numerical results are compared with experimental measurements. The effects of exit and shroud cavities with the leak-age flow are investigated. Time-accurate incompressible Navier-Stokes formulation with the overlapped grid scheme capability was evaluated by using MIT flapping foil experiment. The grid dependency, turbulence model effects, and the effect of order of differencing were investigated. Numerical results were compared against experimental data. The resulting procedure were applied to unsteady flapping foil calculations. Two upstream NACA 0025 foils perform high frequency synchronized motion and generate unsteady flow conditions to the downstream larger stationary foil. Comparison between unsteady experimental data and numerical results from two different moving boundary procedures will be presented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Workshop for CFD Applications in Rocket Propulsion; Apr 19, 1994 - Apr 21, 1994; Huntsville, AL; United States
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  • 13
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    Effects of Heat Release on a Two-Dimensional Reacting Shear Layer (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: The diffusion controlled binary reaction between initially segregated reactants in a two-dimensional low Mach number mixing layers is studied via numerical simulation. The stoichiometric ratio of the reactants is chosen to be much larger than one, as is typical of hydrocarbon flames in air. This results is a flame that is offset from the main vortical region of the mixing layer. In agreement with experimental observations, the flame remains surprisingly uncontorted during the flow evolution and is not entrained into the mixing layer. The effect of the heat release of the flame on the evolution of the mixing layer is thus similar to the effect of a difference in free-stream density between the two sides of the layer. The resulting baroclinic torque inhibits the familiar rolup and pairing of mixing layer vortices common in constant density flows. This also contributes to the layers inability to entrain the flame. The increase in viscosity caused by the heating of the flame reduces the effective Reynolds number of the flow. But, contrary to what has commonly been suggested, this is not the major reason for the inhibition of the usual large-scale mixing layer structures.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Forty Seventh Meeting of the American Physical Society, Division of Fluid Dynamics; Nov 20, 1994 - Nov 22, 1994; Atlanta, GA; United States
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  • 14
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    Heating Analysis of the Lockheed Lifting Body (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: Computational fluid dynamic (CFD) analysis is performed on the Lockheed Lifting Body Single-Stage-to-Orbit vehicle to determine the heat transfer to the vehicle during its descent trajectory. Seven species, chemical nonequilibriurn computations using the GASP code will be completed at several trajectory points to assess the thermal protection requirements of the vehicle. Sophisticated surface boundary conditions including in-depth conduction, catalycity, and a variable temperature wall have been incorporated into the flow solver.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 29th AIAA Thermophysics Conference; Jun 19, 1995 - Jun 22, 1995; San Diego, CA; United States
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  • 15
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    Time-Accurate Incompressible Navier-Stokes Computations with Overlapped Moving Grids (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: MIT flapping foil experiment was used as a validation case to evaluate the current incompressible Navier-Stokes approach with overlapped grid schemes. Steady-state calculations were carried out for overlapped and patched grids. The grid dependency, turbulence model effects, and the effect of order of differencing were investigated. Numerical results were compared against experimental data. The resulting procedure were applied to unsteady flapping foil calculations. Two upstream NACA 0025 foils perform high-frequency synchronized motion and generate unsteady flow conditions to the downstream larger stationary foil. Comparison between unsteady experimental data and numerical results from two different moving boundary procedures will be presented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ASME Fluids Engineering Summer Meeting; Jun 19, 1994 - Jun 23, 1994; Lake Tahoe, CA; United States
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  • 16
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    Development of a Magnetic Refrigerator Operating Between 2K and 10K (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: An adiabatic demagnetization refrigerator (ADR) is under development at NASA-Ames Research Center that will operate between 2 K and 10 K and will provide 50 mW of cool ng at 2 K. Gadolinium Gallium Garnet (GGG) is selected as the refrigerant for the ADR, To minimize temperature gradients in the GGG, thick slices of GGG are sandwiched together with strips of high-purity copper in between them. The copper strips are used to exchange heat between the GGG and the 2 K and the 10 K heat switches. The heat transfer across the Cu-GGG interfaces is improved by placing thin foils of' high-purity indium at the interfaces. The heat switches employed in the ADR have no moving parts. The 10 K heat switch is a helium gas-gap heat switch; while, the 2 K heat switch is a He ll-gap heat switch. A switch is on when its gap Is filled with helium and is off' when the gap is emptied. This is accomplished with an activated carbon pump (ACP). The ACP adsorbs helium when cooled and desorbs it when heated. A superconducting magnet capable of providing 9 T at 2 K is used for the ADR cycle. A prototype of this refrigerator has been built and is currently under test. A detailed design of the ADR and preliminary test results performed on the prototype ADR will be presented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Dagstuhl Seminar on Scientific Visualization; May 22, 1994 - May 27, 1994; Saarbrucken; Germany
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  • 17
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    An Overview of Unsteady Three-Dimensional Navier-Stokes Simulations of Multistage Turbomachinery Flows (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: Fluid dynamics of turbomachines are complicated by inherently three dimensional structures such as endwall boundary layers, hub corner separation bubbles and tip-leakage flows. In addition, the relative motion between rotors and stators causes unsteady aerodynamic interactions to occur between blade rows. It is necessary to understand the aerodynamics associated with these interactions in order to design turbomachines that are both light and compact as well as reliable and efficient. An unsteady, three-dimensional, thin-layer, Navier-Stokes zonal algorithm is used to investigate the unsteady aerodynamics of multi-stage turbines and compressors. Relative motion between rotors and stators is made possible by the use of systems of patched and overlaid grids. Time-averaged pressures and pressure envelopes have been computed for several two- and three-dimensional single- and multi-stage configurations. Flow visualizations and computed results are in good agreement with experimental data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Department of Energy High Performance Computing and Communication Workshop on Computational Fluid Dynamics; Feb 23, 1994 - Feb 25, 1994; Seaside, OR; United States
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  • 18
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    Trajectory Based Heating and Ablation Calculations for MESUR Pathfinder Aeroshell (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Based on the geometry of Mars Environment Survey (MESUR) Pathfinder aeroshell and an estimated Mars entry trajectory, two-dimensional axisymmetric time dependent calculations have been obtained using GIANTS (Gauss-Siedel Implicit Aerothermodynamic Navier-Stokes code with Thermochemical Surface Conditions) code and CMA (Charring Material Thermal Response and Ablation) Program for heating analysis and heat shield material sizing. These two codes are interfaced using a loosely coupled technique. The flowfield and convective heat transfer coefficients are computed by the GIANTS code with a species balance condition for an ablating surface, and the time dependent in-depth conduction with surface blowing is simulated by the CMA code with a complete surface energy balance condition. In this study, SLA-561V has been selected as heat shield material. The solutions, including the minimum heat shield thicknesses over aeroshell forebody, pyrolysis gas blowing rates, surface heat fluxes and temperature distributions, flowfield, and in-depth temperature history of SLA-561V, are presented and discussed in detail.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 19
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    Parallel Preconditioning for CFD Problems on the CM-5 (1994)
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    Publication Date: 2019-07-17
    Description: Up to today, preconditioning methods on massively parallel systems have faced a major difficulty. The most successful preconditioning methods in terms of accelerating the convergence of the iterative solver such as incomplete LU factorizations are notoriously difficult to implement on parallel machines for two reasons: (1) the actual computation of the preconditioner is not very floating-point intensive, but requires a large amount of unstructured communication, and (2) the application of the preconditioning matrix in the iteration phase (i.e. triangular solves) are difficult to parallelize because of the recursive nature of the computation. Here we present a new approach to preconditioning for very large, sparse, unsymmetric, linear systems, which avoids both difficulties. We explicitly compute an approximate inverse to our original matrix. This new preconditioning matrix can be applied most efficiently for iterative methods on massively parallel machines, since the preconditioning phase involves only a matrix-vector multiplication, with possibly a dense matrix. Furthermore the actual computation of the preconditioning matrix has natural parallelism. For a problem of size n, the preconditioning matrix can be computed by solving n independent small least squares problems. The algorithm and its implementation on the Connection Machine CM-5 are discussed in detail and supported by extensive timings obtained from real problem data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: International Workshop on Solution Techniques for Large-Scale CFD Problems; Sep 26, 1994 - Sep 28, 1994; Montreal, Quebec; Canada
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  • 20
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    Comparison of Coupled Radiative Navier-Stokes Flow Solutions with the Project Fire II Flight Data (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: A nonequilibrium, axisymmetric, Navier-Stokes flow solver with coupled radiation has been developed to use in the design of thermal protection systems for vehicles where radiation effects are important. The present method has been compared with an existing flow and radiation solver and with the Project Fire II experimental data. Very good agreement has been obtained over the entire Fire II trajectory with the experimentally determined values of the stagnation radiation intensity in the .2 to 6.2 eV range and with the total stagnation heating. The agreement was significantly better than previous numerical predictions. The effects of a number of flow models are examined to determine which combination of physical models produces the best agreement with the experimental data. These models include radiation coupling, multi-temperature thermal models, finite-rate chemistry, and a quasi-steady-state or Boltzmann assumption for the calculation of the excited electronic states. Finally, the computational efficiency of the present model is evaluated. The radiation properties model developed for this study is shown to offer significant computational savings compared to existing codes.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 21
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    Rotational Relaxation in Nonequilibrium Freejet Expansions of Heated Nitrogen (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Rotational temperatures have been measured in rarefied, nonequilibrium, heated freejet expansions of nitrogen using the electron beam fluorescence technique at the University of California at Berkeley Low Density Wind Tunnel facility. Spectroscopic measurements of the (0,0) band of the first negative system of nitrogen reveal the nonequilibrium behavior in the flowfield upstream of, and through the Mach disk, which forms as the freejet expands into a region of finite back pressure. Results compare well with previous freejet expansion data and computations regarding location of the Mach disk and terminal rotational temperature in the expansion. Measurements are also presented for shock thickness based on the rotational temperature changes in the flow. Thickening shock layers, departures of rotational temperature from equilibrium in the expansion region, and downstream rotational temperature recovery much below that of an isentropic normal shock provide indications of the rarefied, nonequilibrium flow behavior. The data are analyzed to infer constant values of the rotational-relaxation collision number from 2.2 to 6.5 for the various flow conditions. Collision numbers are also calculated in a consistent manner for data from other investigations for which is seen a qualitative increase with increasing temperature. Rotational-relaxation collision numbers are seen as not fully descriptive of the rarefied freejet flows. This may be due to the high degree of nonequilibrium in the flowfields, and/or to the use of a temperature-insensitive rotational-relaxation collision number model in the data analyses.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 22
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    Particle Distribution in Suspension Shear Flow (1994)
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    Publication Date: 2019-07-18
    Description: An earlier proposed constitutive relation for normal stresses originated by random particle fluctuations is used to describe a joint effect of thermal and shear-induced fluctuations on concentrational distributions in suspension flow. Averaged products of components of the fluctuation velocity are evaluated on a basis of the rational mechanics approach combined with a simple kinematic consideration. The equation of momentum conservation of the dispersed phase of a suspension closed with this constitutive relation is applied to unidirectional shear flow in the gravity field and to rotational Couette flow. Coupling of the thermal and shear-induced fluctuations results in that the ability of shear flow to suspend particles has a minimum at a certain particle size, all other things being equal. The developed model provides also for a reasonable explanation of particle distributions observed in Couette flow. The approach based on the consideration of momentum balance for the dispersed phase is proved to lead to an effective equation of convective diffusion of the suspended particles. Coefficients of mutual diffusion due to both thermal and shear-induced fluctuations are drastically different from corresponding self-diffusivities as regards both their scaling and their concentrational dependence.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 23
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    Bubble Formation at a Submerged Orifice in Reduced Gravity (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: The dynamic regime of gas injection through a circular plate orifice into an ideally wetting liquid is considered, when successively detached bubbles may be regarded as separate identities. In normal gravity and at relatively low gas flow rates, a growing bubble is modeled as a spherical segment touching the orifice perimeter during the whole time of its evolution. If the flow rate exceeds a certain threshold value, another stage of the detachment process takes place in which an almost spherical gas envelope is connected with the orifice by a nearly cylindrical stem that lengthens as the bubble rises above the plate. The bubble shape resembles then that of a mushroom and the upper envelope continues to grow until the gas supply through the stem is completely cut off. Such a stage is always present under conditions of sufficiently low gravity, irrespective of the flow rate. Two major reasons make for bubble detachment: the buoyancy force and the force due to the momentum inflow into the bubble with the injected gas. The former force dominates the process at normal gravity whereas the second one plays a key role under negligible gravity conditions. It is precisely this fundamental factor that conditions the drastic influence on bubble growth and detachment that changes in gravity are able to cause. The frequency of bubble formation is proportional to and the volume of detached bubbles is independent of the gas flow rate in sufficiently low gravity, while at normal and moderately reduced gravity conditions the first variable slightly decreases and the second one almost linearly increases as the flow rate grows. Effects of other parameters, such as the orifice radius, gas and liquid densities, and surface tension are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 24
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    The Roles of Large- and Small-Scale Structures in Turbulent Free Shear Layers (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: The occurrence of large-scale coherent structures in turbulent free shear flows (especially the planar mixing layer) has been recognized for some time. Indeed, the observation of such structures in mixing layers did much to promote interest in the study of coherent structures in turbulence. It has been widely assumed that the large-scale structures in these flows are responsible for the entrainment of free-stream fluid and the overall growth of the layer, while the small-scale structures provide mixing and dissipation. A model of scalar mixing based on these ideas was proposed for these flows. However, recent experimental and computational evidence suggests that the dominance of the large-scale structures in turbulent mixing layers is not universal. In addition, there is a substantial variation among experiments in several statistical measures of self-similar mixing layers, for example growth rate and velocity variances. To investigate the importance of large-scale structures, several free shear flows (mixing layers and wakes) have been simulated via direct numerical simulation. The simulations are designed to mimic experimental mixing layers in which the splitter plate boundary layers are turbulent. Different levels of two-dimensional forcing are included resulting in large-scale structures of differing strength and importance. These simulations are used to investigate the role of large-scale coherent structures in free shear layers and the effect of these structures on relevant turbulence statistics and scalar mixing. It is found that the statistics and structures in several experiments involving turbulent mixing layers are in better agreement with simulations that do not exhibit dominant large-scale structures than those in which the common mixing layer structures do dominate. It is also found that the level of forcing can have a profound effect on the qualitative and quantitative features of these shear layer, even when they are nominally self-similar.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 12th U.S. National Congress of Applied Mechanics; Jun 26, 1994 - Jul 01, 1994; Seattle, WA; United States
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  • 25
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    Computational Fluid Dynamics at NASA Ames Research Center (1994)
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    Publication Date: 2019-07-17
    Description: Computational fluid dynamics (CFD) is beginning to play a major role in the aircraft industry of the United States because of the realization that CFD can be a new and effective design tool and thus could provide a company with a competitive advantage. It is also playing a significant role in research institutions, both governmental and academic, as a tool for researching new fluid physics, as well as supplementing and complementing experimental testing. In this presentation, some of the progress made to date in CFD at NASA Ames will be reviewed. The presentation addresses the status of CFD in terms of methods, examples of CFD solutions, and computer technology. In addition, the role CFD will play in supporting the revolutionary goals set forth by the Aeronautical Policy Review Committee established by the Office of Science and Technology Policy is noted. The need for validated CFD tools is also briefly discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Computational fluid dynamics at NASA Ames Research Center; Jun 19, 1994 - Jun 20, 1994; Incline Village, NV; United States
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  • 26
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    Thermal Conductance of Pressed Bimetal Contact Pairs at Liquid Nitrogen Temperatures (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: Large Dewars often use aluminum radiation shields and stainless steel vent lines. A simple, low cost method of making thermal contact between the shield and the line is to deform the shield around the line. A knowledge of the thermal conductance of such a joint is needed to thermally analyze the system. The thermal conductance of pressed metal contacts consisting of one aluminum and one stainless steel contact has been measured at 77 K, with applied forces from 8.9 N to 267 N. Both 5052 or 5083 aluminum were used as the upper contact. The lower contact was 304L stainless steel. The thermal conductance was found to be linear in temperature over the narrow temperature range of measurement. As the force was increased, the thermal conductance ranged from roughly 9 to 21 mW/K within a range of errors from 3% to 8%. Within the range of error no difference could be found between the using either of the aluminum alloys as the upper contact. Extrapolating the data to zero applied force does not result in zero thermal conductance. Possible causes of this anomalous effect are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 15th International Cryogenic Engineering Conference and Industrial Exhibition; Jun 07, 1994 - Jun 10, 1994; Genova; Italy
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  • 27
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    Compressibility Effects on the Passive Scalar Flux Within Homogeneous Turbulence (1994)
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    Publication Date: 2019-07-13
    Description: Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Physics of Fluids (ISSN 1070-6631); 6; 10; 3498-3500
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  • 28
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    Dynamics of Numerics and CFD (1994)
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    Publication Date: 2019-07-18
    Description: This lecture attempts to illustrate the basic ideas of how the recent advances in nonlinear dynamical systems theory (dynamics) can provide new insights into the understanding of numerical algorithms used in solving nonlinear differential equations (DEs). Examples will be given of the use of dynamics to explain unusual phenomena that occur in numerics. The inadequacy of the use of linearized analysis for the understanding of long time behavior of nonlinear problems will be illustrated, and the role of dynamics in studying the nonlinear stability, accuracy, convergence property and efficiency of using time- dependent approaches to obtaining steady-state numerical solutions in computational fluid dynamics (CFD) will briefly be explained.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Lawrence Livermore National Laboratory Special Computational Fluid Mechanics Seminar; Dec 08, 1994; Livermore, CA; United States
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  • 29
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    Merging Intelligent Systems Technologies with CFD Analysis Strategies: Prototype Development at NASA Ames (1994)
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    Publication Date: 2019-07-18
    Description: A collaborative team of researchers from fields of Computational Fluid Dynamics (CFD), fluid physics, computer architectures, and computer science and knowledge engineering have begun work on a prototype system that addresses several of industry's concerns in using NASA-developed CFD codes as part of the design cycle. A major problem exists in the application of CFD technologies within the aeronautics design cycle due primarily to misunderstandings in the ranges of applicability of the various solver codes or turbulence models. Features that arise during the CFD solution process need to be discriminated and recognized as actual flow features with physical support in the geometry and flow conditions of the problem being solved, or as numerical or non-physical errors arising from mis-application of solver code and its parameters, gridding strategies, or discretization. interpolations. The fundamental concept is to develop an intelligent computational system that can accept the engineer's definition of the problem and construct an optimal CFD solution. To do this requires capturing both the knowledge of how to apply the various CFD tools and how to adapt the application of those tools to flow structures as they evolve during the flow simulation. Embedded within this adaptive system approach is the additional desire to automatically identify and quantify the quality of resolution of the pertinent flow structures, be they genuine or error-induced, and then to adjust the solution strategy accordingly. This paper discusses the status of that prototyping effort.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Improving the CFD Application Process Workshop; Nov 08, 1994 - Nov 09, 1994; Stanford, CA; United States
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  • 30
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    Automated Instrumentation, Monitoring and Visualization of PVM Programs Using AIMS (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: We present views and analysis of the execution of several PVM codes for Computational Fluid Dynamics on a network of Sparcstations, including (a) NAS Parallel benchmarks CG and MG (White, Alund and Sunderam 1993); (b) a multi-partitioning algorithm for NAS Parallel Benchmark SP (Wijngaart 1993); and (c) an overset grid flowsolver (Smith 1993). These views and analysis were obtained using our Automated Instrumentation and Monitoring System (AIMS) version 3.0, a toolkit for debugging the performance of PVM programs. We will describe the architecture, operation and application of AIMS. The AIMS toolkit contains (a) Xinstrument, which can automatically instrument various computational and communication constructs in message-passing parallel programs; (b) Monitor, a library of run-time trace-collection routines; (c) VK (Visual Kernel), an execution-animation tool with source-code clickback; and (d) Tally, a tool for statistical analysis of execution profiles. Currently, Xinstrument can handle C and Fortran77 programs using PVM 3.2.x; Monitor has been implemented and tested on Sun 4 systems running SunOS 4.1.2; and VK uses X11R5 and Motif 1.2. Data and views obtained using AIMS clearly illustrate several characteristic features of executing parallel programs on networked workstations: (a) the impact of long message latencies; (b) the impact of multiprogramming overheads and associated load imbalance; (c) cache and virtual-memory effects; and (4significant skews between workstation clocks. Interestingly, AIMS can compensate for constant skew (zero drift) by calibrating the skew between a parent and its spawned children. In addition, AIMS' skew-compensation algorithm can adjust timestamps in a way that eliminates physically impossible communications (e.g., messages going backwards in time). Our current efforts are directed toward creating new views to explain the observed performance of PVM programs. Some of the features planned for the near future include: (a) ConfigView, showing the physical topology of the virtual machine, inferred using specially formatted IP (Internet Protocol) packets; and (b) LoadView, synchronous animation of PVM-program execution and resource-utilization patterns.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: SIAM Conference for Scientific Computing; Feb 15, 1995 - Feb 17, 1995; San Francisco, CA; United States
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  • 31
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    Numerical Generation of Asymmetric Flows about Slender Bodies of Revolution at Extreme Incidence (1994)
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    Publication Date: 2019-07-17
    Description: It is well known that slender bodies of revolution will develop an asymmetric, unsteady flow pattern in experimental tests, if the angle of incidence to the oncoming stream is above a critical value. It has been suggested that the origin of these asymmetric flows may stem from geometric imperfections of the model being tested, or from disturbances in the oncoming stream. In numerical simulations, it is possible to generate bodies of revolution which are perfectly symmetric about their longitudinal axis, and to impose uniform flow conditions which are free from disturbances. The current work presents numerical simulations of the flow about an ogive-cylinder configuration at 40 and 60 degree angle of incidence. These simulations. were performed using numerical algorithms which are also symmetric about the lateral plane of the cylinder body. The flowfields at 40 degree angle of attack were seen to remain symmetric to the round-off accuracy of the computer. At 60 degree angle of attack, a lateral force coefficient developed of O(1) which progressed to an alternate vortex shedding in time. The nature of this lateral force generation and vortex shedding was dependent on the choice of numerical algorithm. The origin of the asymmetries observed in the 60 degree angle of attack computations were traced to round-off errors in the implicit block-matrix inverter. A means of inverting the implicit operator matrices, which maintains the symmetry of the overall numerical algorithm was implemented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA 33rd Aerospace Sciences Meeting and Exhibit; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States
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  • 32
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    Axisymmetric Time-Dependent Computations of Expansion Tube Flow (1994)
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    Publication Date: 2019-07-17
    Description: The goal of this work is to add insight about the flow within expansion tubes by using computational fluid dynamics. This is accomplished by comparing the results of axisymmetric numerical simulations with finite-rate chemistry to data from the HYPULSE expansion tube facility which was previously the NASA Langley expansion tube. The numerical simulations begin at the opening of the primary diaphragm and compute the flow throughout the whole facility and, thus, are able to follow and assess the effect of many of the flow features created during operation of the facility. One particular issue that will be investigated is the effect of boundary layer formation in the acceleration tube on the test gas volume and test gas conditions. Both laminar and turbulent boundary layers will be implemented. The effect of momentary shock reflection off the secondary diaphragm will also be investigated. There is concern that such a reflection will stagnate the test gas and create high levels of dissociated molecules. This is particularly important in propulsion experiments where a freestream composition different from flight conditions may influence ignition and burning data. Several different models of diaphragm rupture will be implemented in order to help understand the importance of this issue.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 33rd Aerospace Science Meeting; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States
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  • 33
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    Hyflite TPS Domain Test Results Ames 2x9 Turbulent Flow Duct (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Detailed experimental data have been obtained on several advanced TUFI systems during their exposure to high temperature high shear supersonic turbulent flow. Dimensional stability of these systems were determined at surface temperatures above 3000 F. Effect of step gap configuration on the thermal performance of the TUFI systems were also evaluated.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 34
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    Towards a Modern Theory of Multiphase Filtration Flow (1994)
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    Publication Date: 2019-07-18
    Description: An alternative theoretical model of joint filtration flow of immiscible incompressible fluids is presented. The model takes into account relaxation processes due to the interchange of the fluids between pores of difference sizes which is driven by capillary forces. The fluids occupy connected regions in a four-dimensional space formed by three coordinates and the pore length scale. When the fluid exchange between pores of given sizes is effected by way of successive flow through pores of all the intermediate sizes, the pressure within each region is governed by a hyperbolic equation, the role of time being played by the pore linear scale. Pressure jumps across hypersurfaces separating the regions equal corresponding values of the capillary pressure. A supplementary condition at any such hypersurface requires the speed of its displacement in the four-dimensional space to coincide with the normal velocity components of both the adjoining fluids. As a result, a principally new statement of multiphase filtration flow problems is gained with allowance for capillary relaxation in the porous space.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 35
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    Incompressible Navier-Stokes Computations with Heat Transfer (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: The existing pseudocompressibility method for the system of incompressible Navier-Stokes equations is extended to heat transfer problems by including the energy equation. The solution method is based on the pseudo compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. Current computations use one-equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard k-epsilon model equations. Both forced and natural convection problems are examined. Numerical results from turbulent reattaching flow behind a backward-facing step will be compared against experimental measurements for the forced convection case. The validity of Boussinesq approximation to simplify the buoyancy force term will be investigated. The natural convective flow structure generated by heat transfer in a vertical rectangular cavity will be studied. The numerical results will be compared by experimental measurements by Morrison and Tran.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Fluids Engineering Summer Meeting; Jun 19, 1994 - Jun 23, 1994; Lake Tahoe, CA; United States
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  • 36
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    Automated Instrumentation, Monitoring and Visualization of PVM Programs Using AIMS (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: We present views and analysis of the execution of several PVM (Parallel Virtual Machine) codes for Computational Fluid Dynamics on a networks of Sparcstations, including: (1) NAS Parallel Benchmarks CG and MG; (2) a multi-partitioning algorithm for NAS Parallel Benchmark SP; and (3) an overset grid flowsolver. These views and analysis were obtained using our Automated Instrumentation and Monitoring System (AIMS) version 3.0, a toolkit for debugging the performance of PVM programs. We will describe the architecture, operation and application of AIMS. The AIMS toolkit contains: (1) Xinstrument, which can automatically instrument various computational and communication constructs in message-passing parallel programs; (2) Monitor, a library of runtime trace-collection routines; (3) VK (Visual Kernel), an execution-animation tool with source-code clickback; and (4) Tally, a tool for statistical analysis of execution profiles. Currently, Xinstrument can handle C and Fortran 77 programs using PVM 3.2.x; Monitor has been implemented and tested on Sun 4 systems running SunOS 4.1.2; and VK uses XIIR5 and Motif 1.2. Data and views obtained using AIMS clearly illustrate several characteristic features of executing parallel programs on networked workstations: (1) the impact of long message latencies; (2) the impact of multiprogramming overheads and associated load imbalance; (3) cache and virtual-memory effects; and (4) significant skews between workstation clocks. Interestingly, AIMS can compensate for constant skew (zero drift) by calibrating the skew between a parent and its spawned children. In addition, AIMS' skew-compensation algorithm can adjust timestamps in a way that eliminates physically impossible communications (e.g., messages going backwards in time). Our current efforts are directed toward creating new views to explain the observed performance of PVM programs. Some of the features planned for the near future include: (1) ConfigView, showing the physical topology of the virtual machine, inferred using specially formatted IP (Internet Protocol) packets: and (2) LoadView, synchronous animation of PVM-program execution and resource-utilization patterns.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 1994 Simulation Multi Conference; May 19, 1994 - May 20, 1994; Oakridge, TN; United States
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  • 37
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    FLOWVIZ (1994)
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    Publication Date: 2019-07-18
    Description: FlowViz is a flow visualization application that uses Line Integral Convolution and the texture mapping capabilities of a graphics workstation to create an animation of flow over a curvilinear grid surface.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 38
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    Development of a General Method for Determining Leak Rates from Limiting Enclosures (1994)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: This paper discusses the development of a general method for the determination of very low leak rates from limiting enclosures. There are many methods that can be used to detect and repair leaks from enclosures. Many methods have also been proposed that allow the estimation of actual leak rates, usually expressed as enclosure volume turnover. The proposed method combines measurements of the state variables (pressure, temperature, and volume) as well as the change in the concentration of a tracer gas to estimate the leak rate. The method was applied to the containment enclosure of the Engineering Development Unit of the CELSS Test Facility, currently undergoing testing at the NASA Ames Research Center.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 24th International Conference on Environmental Systems; Jun 20, 1994 - Jun 23, 1994; Friedrichshafen; Germany
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  • 39
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    Rapid Distortion Theory for Compressible Homogeneous Turbulence Under Isotropic Mean Strain (1994)
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    Publication Date: 2019-07-18
    Description: The case of isotropic compressible turbulence subjected to rapid isotropic compression is studied using inviscid rapid distortion theory and direct numerical simulation. An exact solution to the rapid distortion problem is given, and results are compared to those of direct numerical simulation. Implications for modelling turbulent flows are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Second Symposium on Transitional and Turbulent Compressible Flows 1996 Joint ASME/SME Fluid Engineering Conference; Aug 13, 1995 - Aug 18, 1995; Hilton Head, SC; United States
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  • 40
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    CFD Optimization on Network-Based Parallel Computer System (1994)
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    Publication Date: 2019-07-18
    Description: Combining multiple engineering workstations into a network-based heterogeneous parallel computer allows application of aerodynamic optimization with advance computational fluid dynamics codes, which is computationally expensive in mainframe supercomputer. This paper introduces a nonlinear quasi-Newton optimizer designed for this network-based heterogeneous parallel computer on a software called Parallel Virtual Machine. This paper will introduce the methodology behind coupling a Parabolized Navier-Stokes flow solver to the nonlinear optimizer. This parallel optimization package has been applied to reduce the wave drag of a body of revolution and a wing/body configuration with results of 5% to 6% drag reduction.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 10th AIAA Computing in Aerospace Meeting; Mar 12, 1994 - Mar 18, 1994; San Antonio, TX; United States
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  • 41
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    On the Dynamics of Computing a Chemically Relaxed Nonequilibrium Flow (1994)
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    Publication Date: 2019-07-18
    Description: In order to gain insights into the strong dependence of numerical solutions on initial data for finite time steps, a set of nonlinear test problems rich enough to capture the behavior of difference schemes were recently identified and the numerical basins of attraction for these problems were computed using commonly used time discretizations in CFD. Our study revealed a wealth of surprisingly nonlinear behavior of numerical schemes that were not observed before, in particular for the implicit time discretizations that are commonly used in CFD. The goal of this work is to apply these tools to study a practical model from non-equilibrium flowfield relaxation. This type of problem arises in chemically nonequilibrium hypersonic flows such as in a shock tube experiment or an expanding nozzle. Here we consider a reacting mixture of (N2, N) for an inviscid one-dimensional steady model. Preliminary numerical results indicate that, aside from the possibility of spurious numerical solutions being introduced by the time discretizations, limitations on the model for physical or accurate solutions may also play a part in the dynamics observed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ICFD Conference on Numerical Methods for Fluid Dynamics; Apr 03, 1995 - Apr 06, 1995; Oxford; United Kingdom
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  • 42
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    Compressible Turbulent Channel Flows: DNS Results and Modeling (1994)
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    Publication Date: 2019-07-18
    Description: The present paper addresses some topical issues in modeling compressible turbulent shear flows. The work is based on direct numerical simulation of two supersonic fully developed channel flows between very cold isothermal walls. Detailed decomposition and analysis of terms appearing in the momentum and energy equations are presented. The simulation results are used to provide insights into differences between conventional time-and Favre-averaging of the mean-flow and turbulent quantities. Study of the turbulence energy budget for the two cases shows that the compressibility effects due to turbulent density and pressure fluctuations are insignificant. In particular, the dilatational dissipation and the mean product of the pressure and dilatation fluctuations are very small, contrary to the results of simulations for sheared homogeneous compressible turbulence and to recent proposals for models for general compressible turbulent flows. This provides a possible explanation of why the Van Driest density-weighted transformation is so successful in correlating compressible boundary layer data. Finally, it is found that the DNS data do not support the strong Reynolds analogy. A more general representation of the analogy is analysed and shown to match the DNS data very well.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 43
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    Observations of Laminar Surface Shear Stress Patterns on the Sidewall of a Rectangular, Mach 3 Quiet Tunnel Using Liquid Crystal Coatings (1994)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: A shear-stress--sensitive liquid crystal coating (LCC) was used to visualize the surface shear stress distribution on the flat sidewall of the MSU quiet supersonic tunnel as a function of flow stagnation pressure. Under conditions of quiet operation, the LCC color-change response indicated the existence of a nonuniform surface shear stress distribution. This shear pattern was characterized by an elongated, down st ream-point ing triangular region of relatively low shear, with its apex on and its axis coincident with, the sidewall centerline. This low-shear zone was bounded symmetrically by two regions of relatively higher shear; these high-shear zones originated within the concave-curvature portion of the nozzle, in the corners between the flat sidewall and the contoured upper and lower nozzle surfaces. A 3-D Navier-Stokes code was used to compute the pressure and surface shear distributions on the sidewall. Flow-expansion-induced transverse pressure gradients on the nozzle sidewall generated symmetric inflows from the corners towards the sidewall centerline; these inflows caused a thickening of the sidewall boundary layer along the centerline, resulting in lower shear stresses consistent with the liquid crystal results. Peripherally nonuniform laminar boundary layer development, and the associated stability of such complex 3-D flows, must be considered in quiet-tunnel applications using rectangular nozzles. A color video will be shown.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Fluid Dynamics; Nov 20, 1994 - Nov 24, 1994; Atlanta, GA; United States
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  • 44
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    Hypersonic Nozzle/Afterbody Experiment: Flow Visualization and Boundary Layer Experiments (1994)
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    Publication Date: 2019-07-17
    Description: This study was conducted to experimentally characterize the flow field created by the interaction of a single-expansion-ramp-nozzle (SERN) flow with a hypersonic external stream Data were obtained from a generic nozzle/afterbody model in the 3.5-Foot Hypersonic Wind Tunnel of the NASA Ames Research Center in a cooperative experimental program involving Ames and the McDonnell Douglas Aerospace. The model design and test planning were performed in close cooperation with members of the Ames computational fluid dynamics (CFD) team for the National Aero-Space Plane (NASP) program. This paper presents experimental results consisting of oil-flow and shadowgraph flow-visualization photographs, afterbody surface-pressure distributions, boundary-layer rake measurements, and Preston-tube skin-friction measurements.
    Keywords: Fluid Mechanics and Thermodynamics
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    Turbulent Heat Transfer Characteristics in the Shear Layer of a Separated Flow (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Experiments were performed to study the evolution of the heat transfer structure in a separated free shear layer region of an incompressible separated turbulent boundary layer flow behind a backward-facing step. While there is an abundance of velocity field measurements of separated flows, heat transfer measurements are rather scarce, thus limiting assessment of the heat transfer physics and its accurate modeling. The purpose of the paper is twofold: to improve an understanding of effects of flow separation on heat transfer characteristics, and to provide data for turbulence modeling and computation. The boundary layer upstream of the step was turbulent and fully developed. A constant temperature surface boundary condition was imposed upstream and downstream of the step for the heat transfer study. An internal mixing-layer like flow forms and grows from the step lip within the original boundary layer. The turbulent structure of the flow evolving downstream, however, does not switch immediately to that of a mixing layer over the entire shear layer thickness. Measurements of mean and fluctuating velocity and temperature fields indicate that the internal layer spreads gradually in the transverse direction while the outer part of the original boundary layer is effectively unperturbed. The results in this paper have not been previously reported.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Turbulence Heat and Mass Transfer; Aug 09, 1994 - Aug 12, 1994; Lisabon; Portugal
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    Aerothermodynamics of Pyrolizing Surfaces in Hypersonic Rarefied Flows (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Direct simulation Monte Carlo (DSMC) calculations of rarefied flows about entry bodies typically employ a fixed surface temperature or a radiative-equilibrium energy balance to compute that temperature. Such boundary conditions neglect any effects of heat capacitance and heat conduction in the spacecraft heat shield and, therefore, provide an upper bound for the surface temperature. Such calculations also neglect pyrolysis from the heat shield which can be significant for a high-energy incident flow at very low densities. Accurate prediction of both heating and aerodynamic forces requires including pyrolysis and surface heat transfer in the models for gas-surface interaction employed in DSMC methods. Although these physical models have long appeared in various continuum flow calculation codes, they have only recently appeared in DSMC codes which are required to simulate rarefied flows during entry at high altitudes. In the current implementation, routines from the widely distributed Charring Material Thermal Response and Ablation (CMA) program are coupled into a DSMC code to calculate the one-dimensional heat transfer into the carbon phenolic heat shield at each point on a vehicle surface. Temperature-dependent material properties, surface re-radiation, and in-depth pyrolysis were included in the calculation, but surface ablation was neglected. Sample calculations for entry of the Galileo probe into the atmosphere of Jupiter demonstrate that including pyrolysis in the model leads to significant differences in predicted aerodynamics. Granted, the drag coefficient does not depend strongly on the surface temperature which can itself be significantly below the radiative equilibrium value during entry. However, the surface mass flux due to pyrolysis of the material is significant once the probe drops to altitudes characterized by transition flow. This leads to a noticeable increase in drag and a decrease in heating compared to a body without pyrolysis.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: International Symposium of Rarefied Gas Dynamics; Jul 25, 1994 - Jul 29, 1994; Oxford; United Kingdom
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    Fluid channeling system (1994)
    In:  CASI
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    Publication Date: 2019-08-16
    Description: A fluid channeling system includes a fluid ejector, a heat exchanger, and a fluid pump disposed in series flow communication The ejector includes a primary inlet for receiving a primary fluid, and a secondary inlet for receiving a secondary fluid which is mixed with the primary fluid and discharged therefrom as ejector discharge. Heat is removed from the ejector discharge in the heat exchanger, and the heat exchanger discharge is compressed in the fluid pump and channeled to the ejector secondary inlet as the secondary fluid In an exemplary embodiment, the temperature of the primary fluid is greater than the maximum operating temperature of a fluid motor powering the fluid pump using a portion of the ejector discharge, with the secondary fluid being mixed with the primary fluid so that the ejector discharge temperature is equal to about the maximum operating temperature of the fluid motor.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 48
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    Parallel DSMC Solution of Three-Dimensional Flow Over a Finite Flat Plate (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: This paper describes a parallel implementation of the direct simulation Monte Carlo (DSMC) method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a good load balance. Performance tests are conducted using the code to evaluate various remapping and remapping-interval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen flow over a finite-thickness flat plate. It is shown that the parallel algorithm produces results which compare well with experimental data. Moreover, it yields significantly faster execution times than the scalar code, as well as very good load-balance characteristics.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 94-0219
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    Effect of Far-Field Boundary Conditions on Boundary-Layer Transition (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The effect of far-field boundary conditions on the evolution of a finite-amplitude two-dimensional wave in the Blasius boundary layer is assessed. With the use of the parabolized stability equations (PSE) theory for the numerical computations, either asymptotic, Dirichlet, Neumann or mixed boundary conditions are imposed at various distances from the wall. The results indicate that asymptotic and mixed boundary conditions yield the most accurate mean-flow distortion and unsteady instability modes in comparison with the results obtained with either Dirichlet or Neumann conditions.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 50
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    Interface Configuration Experiment: Preliminary Results (1994)
    In:  CASI
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    Publication Date: 2019-07-10
    Description: The Interface Configuration Experiment (ICE) was carried out on USML-1 to investigate liquid-gas interfaces in certain rotationally-symmetric containers having prescribed, mathematically derived shapes. These containers have the property that they admit an entire continuum of distinct equilibrium rotationally-symmetric interfaces for a given liquid volume and contact angle. Furthermore, it can be shown that none of these interfaces can be stable. It was found, after the containers were filled in orbit, that an initial equilibrium interface from the symmetric continuum re-oriented, when perturbed, to a stable interface that was not rotationally symmetric, in accordance with the mathematical theory.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, Volume 2; 525-539; NASA-CP-3272-Vol-2
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    Numerical Simulation of Inlet Bleed with Circular Holes on Plate Under Shock-Wave/Boundary-Layer Interactions (1994)
    In:  Other Sources
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    Publication Date: 2019-08-13
    Description: A numerical study was performed to investigate the shock-wave/boundary-layer interactions on a flat plate with bleed through one or more circular holes that vent into a plenum. The bleed-hole patterns considered for the study include in-line multiple holes and staggered multiple-row holes that are configured to simulate the patterns used in inlet bleed systems of high performance aircraft. The focus of the study was to examine how the bleed through multiple holes affect bleed rate and the pressure and Mach number distributions. Since the bleed performance was found sensitive to the change in bleed conditions, a computational procedure was developed to give a good turnaround computational time for parametric studies involving changes in bleed hole geometry and the structure of shock-wave/boundary-layer flowfield. The procedure includes the grid-generation methodology and the flow simulation with solutions from the Navier-Stokes equations. The computational techniques permit analysis of complex bleed systems and make possible the investigation of a broader range of design variables associated with inlet bleed operation.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA Workshop on Surface Modeling, Grid Generation and Related Issues in CFD Solutions; May 09, 1995 - May 11, 1995; Cleveland, OH; United States
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    Micro-grooved heat transfer combustor wall (1994)
    In:  CASI
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    Publication Date: 2019-08-17
    Description: A gas turbine engine hot section combustor liner is provided a non-film cooled portion of a heat transfer wall having a hot surface and a plurality of longitudinally extending micro-grooves disposed in the portion of the wall along the hot surface in a direction parallel to the direction of the hot gas flow. The depth of the micro-grooves is very small and on the order of magnitude of a predetermined laminar sublayer of a turbulent boundary layer. The micro-grooves are sized so as to inhibit heat transfer from the hot gas flow to the hot surface of the wall while reducing NOx emissions of the combustor relative to an otherwise similar combustor having a liner wall portion including film cooling apertures. In one embodiment the micro-grooves are about 0.001 inches deep and have a preferred depth range of from about 0.001 inches to 0.005 inches and which are square, rectangular, or triangular in cross-section and the micro-grooves are spaced about one width apart.
    Keywords: Fluid Mechanics and Thermodynamics
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    The Nonlinear Evolution of the Inviscid Secondary Instability of Streamwise Vortex Structures (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The weakly nonlinear evolution of an inviscid marginally unstable wave growing on a boundary layer supporting a streamwise vortex structure is investigated. The nonlinear growth of the wave is found to be controlled by the diffusion layer located at the edge of the critical layer associated with the wave. The evolution equation is found to depend on the upstream history of the wave and the solution of the equation suggests that the wave either restructures the mean state so as to make it stable or develops a singularity at a finite distance downstream of the point of neutral stability.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 54
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    Parallel Computational Fluid Dynamics: Current Status and Future Requirements (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: One or the key objectives of the Applied Research Branch in the Numerical Aerodynamic Simulation (NAS) Systems Division at NASA Allies Research Center is the accelerated introduction of highly parallel machines into a full operational environment. In this report we discuss the performance results obtained from the implementation of some computational fluid dynamics (CFD) applications on the Connection Machine CM-2 and the Intel iPSC/860. We summarize some of the experiences made so far with the parallel testbed machines at the NAS Applied Research Branch. Then we discuss the long term computational requirements for accomplishing some of the grand challenge problems in computational aerosciences. We argue that only massively parallel machines will be able to meet these grand challenge requirements, and we outline the computer science and algorithm research challenges ahead.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: RNR-92-004
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  • 55
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    CFD Optimization on Network-Based Parallel Computer System (1994)
    In:  Other Sources
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    Publication Date: 2019-08-13
    Description: Combining multiple engineering workstations into a network-based heterogeneous parallel computer allows application of aerodynamic optimization with advance computational fluid dynamics codes, which is computationally expensive in mainframe supercomputer. This paper introduces a nonlinear quasi-Newton optimizer designed for this network-based heterogeneous parallel computer on a software called Parallel Virtual Machine. This paper will introduce the methodology behind coupling a Parabolized Navier-Stokes flow solver to the nonlinear optimizer. This parallel optimization package has been applied to reduce the wave drag of a body of revolution and a wing/body configuration with results of 5% to 6% drag reduction.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA CAS Workshop; Mar 07, 1995 - Mar 09, 1995; Moffett Field, CA; United States
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    Wind Tunnel Results of Pneumatic Forebody Vortex Control Using Rectangular Slots a Chined Forebody (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A subsonic wind tunnel investigation of pneumatic vortex flow control on a chined forebody using slots was accomplished at a dynamic pressure of 50 psf resulting in a R(n)/ft of 1.3 x 10(exp 6). Data were acquired from angles of attack ranging from -4deg to +34deg at side slips of +0.4deg and +10.4deg. The test article used in this study was the 10% scale Fighter Lift and Control (FLAC) advanced diamond winged, vee-tailed fighter configuration. Three different slot blowing concepts were evaluated; outward, downward, and tangential with ail blowing accomplished asymmetrically. The results of three different mass flows (0.067, 0.13, and 0.26 lbm/s; C(sub mu)'s of less than or equal to 0.006, 0.011. and 0.022 respectively) were analyzed and reported. Test data are presented on the effects of mass flows, slot lengths and positions and blowing concepts on yawing moment and side force generation. Results from this study indicate that the outward and downward blowing slots developed yawing moment and side force increments in the direction opposite of the blowing side while the tangential blowing slots generated yawing moment and side force increments in the direction towards the blowing side. The outward and downward blowing slots typically produced positive pitching moment increments while the tangential blowing slots typically generated negative pitching moment increments. The slot blowing nearest the forebody apex was most effective at generating the largest increments and as the slot was moved aft or increased in length, its effectiveness at generating forces and moments diminished.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 94-1854 , AIAA 12th Applied Aerodynamics Conference; Jun 20, 1994 - Jun 23, 1994; Colorado Springs, CO; United States
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    Rotational Relaxation Analysis of Nitrogen in Low-Density Freejet Expansions (1994)
    In:  CASI
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    Publication Date: 2019-07-10
    Description: The phenomena of rotational relaxation of nitrogen has been examined by numerous investigators over many years. One of the experiments which has been performed examines nonequilibrium flow in low-density free jet expansions. Data have been taken in such flows using a variety of techniques, including time-of-flight methods and electron beam fluorescence spectroscopy. The direct flow properties measured in these different investigations, such as density and translational, rotational and vibrational temperatures generally show reasonable agreement. However, this kind of correlation from experiment to experiment tends to be lost when these data are analyzed to obtain rotational relaxation time or collision number. The goal of such data analyses is to generate a succinct model for rotational relaxation in nitrogen which is essential for the computation of nonequilibrium rarefied flows. The objective of the present work is to process a large body of experimental data in a consistent manner to yield relaxation model parameters of the greatest utility for flow computations.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 18th Ground Test Conference: The Electron Beam Fluorescence Technique in Hypersonic Aerothermodynamics; 20-24 Jun. 1994; Colorado Springs, CO; United States|19th International Symposium on Purified Gas Dynamics; Oxford; United Kingdom
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    Active Control of Instabilities in Laminar Boundary-Layer Flow (1994)
    In:  CASI
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    Publication Date: 2019-07-10
    Description: This study focuses on the suppression of instability growth using an automated active-control technique. The evolution of 2D disturbances that are spatially growing in a flat-plate boundary layer are computed with a spatial DNS code. A controller receives wall sensor information (pressure or shear) as input and provides a signal that controls an actuator response as output. The control law assumes that wave cancellation is valid. The results indicate that a measure of wave cancellation can be obtained for small- and large-amplitude instabilities without feedback; however, feedback is required to optimize the control amplitude and phase for exact wave cancellation.
    Keywords: Fluid Mechanics and Thermodynamics
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    Compact contacting device (1994)
    In:  CASI
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    Publication Date: 2019-07-12
    Description: An apparatus comprising a rotatable mass of structured packing for mass or heat transfer between two contacting fluids of different densities wherein the packing mass is made up of corrugated sheets of involute shape relative to the axis of the packing mass and form a logarithmic spiral curved counter to the direction of rotation.
    Keywords: Fluid Mechanics and Thermodynamics
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    Large Eddy Simulation of Homogeneous Rotating Turbulence (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Study of turbulent flows in rotating reference frames has proven to be one of the more challenging areas of turbulence research. The large number of theoretical, experimental, and computational studies performed over the years have demonstrated that the effect of solid-body rotation on turbulent flows is subtle and remains exceedingly difficult to predict. Because of the complexities associated with non-homogeneous turbulence, it is worthwhile to examine the effect of steady system rotation on the evolution of an initially isotropic turbulent flow. The assumption of statistical homogeneity considerably simplifies analysis and computation; calculation of homogeneous turbulence is further motivated since it possesses the essential physics found in more complex rotating flows. The principal objectives of the present study have therefore been to increase our fundamental understanding of turbulent flows in rotating reference frames through an examination of the asymptotic state of homogeneous rotating turbulence; particularly as to the existence of an asymptotic state which is self similar. Knowledge of an asymptotic similarity state permits prediction of the ultimate statistical evolution of the flow without requiring detailed knowledge of the complex, and not well understood, non-linear transfer processes. Aside from examination of possible similarity states in rotating turbulence, of further interest in this study has been an examination of the degree to which solid-body rotation induces a two-dimensional state in an initially isotropic flow.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 74th AGARD Symposium on Application of Direct and Large Eddy Simulation to Transition and Turbulence; Apr 18, 1994 - Apr 21, 1994; Chania; Greece
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    On the Vortical-Flow Prediction Capability of an Unstructured-Grid Euler Solver (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The results from a concentrated computational effort are presented with the primary objective being directed at evaluating the vortical-flow-prediction capability of an unstructured-grid Euler solver. Both viscous and inviscid solutions, obtained from an established structured-grid method, along with an experimental wind-tunnel data are used as bench-mark measures to assess the validity of the unstructured-grid Euler results. Viscous effects on vortical flows are first identified by comparing the viscous and inviscid solutions obtained form the structured-grid method. Computational data analysis are then presented which reveal excellent correlations between the inviscid structured and unstructured-grid results in terms of off-surface flow structures, surface pressure distribution and the predicted longitudinal aerodynamic characteristics. The sensitivity of the unstructured-grid inviscid solutions to grid refinement is also discussed along with an analysis of the convergence and performance characteristics for each method.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 94-0163 , AIAA 32nd Aerospace Sciences Meeting and Exhibit; Jan 10, 1994 - Jan 13, 1994; Reno, NV; United States
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    Development and Applications of 3D Cartesian CFD Technology (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The urgent need for dramatic reductions in aircraft design cycle time is focusing scrutiny upon all aspects of computational fluid dynamics (CFD). These reductions will most likely come not from increased reliance upon user-interactive (and therefore time-expensive) methods, but instead from methods that can be fully automated and incorporated into 'black box' solutions. In comparison with tetrahedral methods, three-dimensional Cartesian grid approaches are in relative infancy, but initial experiences with automated Cartesian techniques are quite promising. Our research is targeted at furthering the development of Cartesian methods so that they can become key elements of a completely automatic grid generation/flow solution procedure applicable to the Euler analysis of complex aircraft geometries.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA Lewis Surface Modeling and Grid Generation Workshop; May 09, 1995 - May 11, 1995; Cleveland, OH; United States
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    Flow Visualization Techniques in Wind Tunnel Tests of a Full-Scale F/A-18 Aircraft (1994)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. The purpose of the flow-visualization experiments was to document the forebody and leading edge extension (LEX) vortex interaction along with the wing flow patterns at high angles of attack and low speed high Reynolds number conditions. This investigation used surface pressures in addition to both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, LEXS, and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system for three-dimension vortex tracking. The flow visualization experiments were conducted over an angle of attack range from 20 deg to 45 deg and over a sideslip range from -10 deg to 10 deg. The various visualization techniques as well as the pressure distributions were used to understand the flow field structure. The results show regions of attached and separated flow on the forebody, canopy, and wings as well as the vortical flow over the leading-edge extensions. This paper will also present flow visualization comparisons with the F-18 HARV flight vehicle and small-scale oil flows on the F-18.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 7th International Symposium of Flow Visualization; Sep 11, 1995 - Sep 14, 1995; Seattle, WA; United States
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    On the Connection Between One-and Two-Equation Models of Turbulence (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A formalism will be presented that allows the transformation of two-equation eddy viscosity turbulence models into one-equation models. The transformation is based on an assumption that is widely accepted over a large range of boundary layer flows and that has been shown to actually improve predictions when incorporated into two-equation models of turbulence. Based on that assumption, a new one-equation turbulence model will be derived. The new model will be tested in great detail against a previously introduced one-equation model and against its parent two-equation model.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Tenth Symposium on Turbulent Shear Flows; Aug 14, 1995 - Aug 16, 1995; PA; United States
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    Visual Environments for CFD Research (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This viewgraph presentation gives an overview of the visual environments for computational fluid dynamics (CFD) research. It includes details on critical needs from the future computer environment, features needed to attain this environment, prospects for changes in and the impact of the visualization revolution on the human-computer interface, human processing capabilities, limits of personal environment and the extension of that environment with computers. Information is given on the need for more 'visual' thinking (including instances of visual thinking), an evaluation of the alternate approaches for and levels of interactive computer graphics, a visual analysis of computational fluid dynamics, and an analysis of visualization software.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Improving the CFD Application Process Workshop; Nov 08, 1994 - Nov 09, 1994; Stanford, CA; United States
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    Interactive Visualization of Computational Fluid Dynamics using Mosaic (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Web provides new Methods for accessing Information world-wide, but the current text-and-pictures approach neither utilizes all the Web's possibilities not provides for its limitations. While the inclusion of pictures and animations in a paper communicates more effectively than text alone, It Is essentially an extension of the concept of "publication." Also, as use of the Web increases putting images and animations online will quickly load even the "Information Superhighway." We need to find forms of communication that take advantage of the special nature of the Web. This paper presents one approach: the use of the Internet and the Mosaic interface for data sharing and collaborative analysis. We will describe (and In the presentation, demonstrate) our approach: using FAST (Flow Analysis Software Toolkit), a scientific visualization package, as a data viewer and interactive tool called from MOSAIC. Our intent is to stimulate the development of other tools that utilize the unique nature of electronic communication.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 2nd International World Wide Web Conference; Oct 17, 1994 - Oct 20, 1994; Chicago, IL; United States
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    Electronic Resource
    Electronic Resource
    N(B(NMe2)2)(Si(NMe2)3)(Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3)  -  Synthese und Charakterisierung neuer molekularer Einkomponentenvorläufer für nitridische und carbonitridische Keramiken (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 366-370 
    Details
    ISSN: 0044-2313
    Keywords: Bis(dimethylamino)boryl-tris(dimethylamino)silyl-tris(dimethylamino)titanylamin ; N,N′-Bis(tris(dimethylamino)-silyl)-1,1,3,3-tetrakis(dimethylamino)cyclobistitanazan, Trimethylsilyl-tris(dimethylamino)silyl-tris(dimethylamino)titanylamin ; Trimethylsilyl-tris(dimethylamino)-silylamin ; synthesis ; nmr spectra ; mass spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N(B(NMe2)2)(Si(NMe2)3) (Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3)  -  Synthesis and Characterization of New Molecular Single-source Precursors for Nitride and Carbonitride CeramicsSynthesis and spectroscopic data of the title compounds are reported. [N(Si(NMe2)3)(Ti(NMe2)2)]2 crystallizes in the space group P1, a = 8.406(7), b = 10.673(8), c = 10.872(6) Å, α = 68.45(4)°, β = 71.72(4)°, γ = 78.11(7)°, 2 877 diffractometer data (Fo ≥ 2σFo), R = 0.051. The compound is characterized by a planar four-membered Ti2N2-ring with exocyclic tris(dimethylamino)silyl substituents attached to the nitrogen atoms of the ring.
    Notes: Darstellung, kernresonanz- und massenspektroskopische Daten der Titelverbindungen werden mitgeteilt. [N(Si(NMe2)3)(Ti(NMe2)2)]2 kristallisiert in der Raumgruppe P1 mit den Gitterkonstanten a = 8,406(7), b = 10,673(8), c = 10,872(6) Å, α = 68,45(4)°, β = 71,72(4)°, γ = 78,11(7)°. 2 877 Diffraktometerdaten (Fo ≥ 2σFo), R = 0,051. Die Verbindung besitzt einen planaren Ti2N2-Vierring mit exocyclischen Tris(dimethylamino)silylsubstituenten an den Stickstoffatomen des Rings.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200228
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    Electronic Resource
    Electronic Resource
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994) 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200301
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  • 69
    Electronic Resource
    Electronic Resource
    Darstellung und Strukturen einiger N-(Tri-t-butoxysilyl)anilin-Derivate (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 377-384 
    Details
    ISSN: 0044-2313
    Keywords: One-pot reactions of tri-t-butoxychlorosilane, K-t-butanolate and substituted anilines. Crystal structure analyses of N-(tri-t-butoxysilyl)-aniline, C18H33NO3Si ; N-(tri-t-butoxysilyl)-p-nitroaniline, C18H32N2O5Si ; N-Methyl-(N-tri-t-butoxysilyl)-p-nitroaniline C19H34N2O5Si ; N-(tri-t-butoxysilyl)-p-cyanoaniline, C19H32N2O3Si ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Structures of N-(tri-t-butoxysilyl)aniline CompoundsPara-substituted N-(tri-t-butoxysilyl)anilines (t-BuO)3SiNRC4H4X-p, R = H, CH3, with substituents of high electron affinity (X = CN, NO2) were prepared by a one-pot reaction of tri-t-butoxychlorsilane, potassium t-butanolate and substituted anilines. Corresponding compounds with substituents of low electron affinity (X = OMe, H) preferably were prepared by metalation of anilines with sodium amide. Four crystal structures were determined. N-(tri-t-butoxysilyl)-p-nitro-aniline, N-methyl-(N-tri-t-butoxysilyl)-p-nitroaniline and N-(tri-t-butoxysilyl)-p-cyanoaniline crystallize at 298 K monoclinically, N-(tri-t-butoxysilyl)aniline crystallizes orthorhombically.
    Notes: Derivate des para-substituierten N-(Tri-t-butoxysilyl)anilins (t-BuO)3SiNRC6H4X-p, R = H, CH3 mit Substituenten hoher Elektronenaffinität (X = CN, NO2) wurden nach einem neuen Eintopfverfahren aus Tri-t-butoxychlorsilan, Kalium-t-butanolat und dem entsprechend substituierten Anilin dargestellt. Für Substituenten niederer Elektronenaffinität (X = OMe, H) wird die Methode der Metallierung von Anilinen mit Natriumamid bevorzugt. Vier Kristallstrukturen wurden bestimmt. N-(Tri-t-butoxysilyl)-p-nitroanilin, N-Methyl-(N-tri-t-butoxysilyl)-p-nitroanilin und N-(Tri-t-butoxysilyl)-p-cyanoanilin kristallisieren bei 298 K monoklin, N-(Tri-t-butoxysilyl)anilin kristallisiert orthorhombisch.
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    Densities of Melts of the System KF—K2MoO4—B2O3 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 385-388 
    Details
    ISSN: 0044-2313
    Keywords: Density of melts ; system potassium fluoride/potassium molybdate/boron oxide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dichte der Schmelzen des System KF/K2MoO4/B2O3Die Dichte der Schmelzen des Systems KF/K2MoO4/B2O3 wurden gemessen. Das Molvolumen des binären Systems KF/K2MoO4 weicht nur wenig vom idealen Verlauf ab, was die starke thermische Dissoziation des kongruent schmelzenden K3FMoO4 anzeigt. Im System KF/B2O3 führt die Bildung von KBF4 und K2B4O7 zur Volumenzunahme, wie auch im System K2MoO4/B2O3. In letzterem kann die Volumenzunahme durch die Bildung des Heteropolyanions [BMo6O24]9- beschrieben werden. Die deutliche Abweichung vom idealen Verhalten des Systems KF/K2MoO4/B2O3 weist auf eine ausgeprägte ternäre Wechselwirkung, wahrscheinlich auf die Substitution von Sauerstoff in der Koordinationssphäre des Heteropolyanions durch Fluor.
    Notes: The density of melts of the system KF—K2MoO4—B2O3 was measured. The molar volume in the binary system KF—K2MoO4 deviates only little from the ideal course, which indicates the extended thermal dissociation of the congruently melting additive compound K3FMoO4.In the KF—B2O3 binary system the formation of KBF4 and K2B4O7 leads to the volume expansion, like in the K2MoO4—B2O3 system, where the volume expansion may be described by the formation of the heteropolyanions [BMo6O24]9-. The significant deviation from the ideal behaviour in the ternary system KF—K2MoO4—B2O3 refers to the pronounced interaction, most probably due to the substitution of oxygen atoms in the coordination sphere of the heteropolyanion with the fluorine ones.
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    Synthesis and Crystal Structure of Hg5Sb2I6 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 389-392 
    Details
    ISSN: 0044-2313
    Keywords: Mercury antinionide iodide, Hg5Sb2I6 ; Preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Kristallstruktur von Hg5Sb2I6Das Antimonid-Iodid von Quecksilber, Hg5Sb2I6, früher irrtümlich als Hg3Sb2I4 formuliert, wurde in Standardampullen synthetisiert. Einkristalle wurden mittels Transport über die Gasphase erhalten. Hg5Sb2I6: Raumgruppe Pc21n, Gitterparameter: a = 8,108(1), b = 10,702(1), c = 21,295(1) Å. Die Struktur (Einkristall) ist aus [HgSbI3]-Tetraedern und [HgSbI2]-Dreiecken aufgebaut. Alle Antimonatome sind paarweise zu Sb24--Hanteln verbunden. Die Struktur wird mit anderen Strukturen, die Sb24--Hanteln enthalten, verglichen.
    Notes: Mercury antimonide iodide, Hg5Sb2I6, previously and erroneously reported as Hg3Sb2I4 was synthesized using standard ampoule technique. A gas-phase transport reaction was applied for preparation of single crystals. Hg5Sb2I6 crystallizes in the space group Pc21n (No. 33) with unit cell dimensions: a = 8.108(1), b = 10.702(1), c = 21.295(1) Å. Crystal structure solved using single crystal X-ray data is built of [HgSbI3] tetrahedra and [HgSbI2] triangles. All antimony atoms are joined into Sb24- dumbbells. The structure is compared with ones containing similar Sb24- dumbbells.
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    Alkylidinphosphane und -arsane. I [P ≡ C—S]-[Li(dme)3]+ - Synthese und StrukturProfessor Reinhard Schmutzler zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 405-417 
    Details
    ISSN: 0044-2313
    Keywords: Tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide ; [P≡C—S]--anion ; [Li(dme)3]+-cation ; heteroatom-substituted λ3-phosphaalkynes ; nmr and ir data ; X-ray structure determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylidynephosphanes and -arsanes. I [P ≡ C—S]-[Li(dme)3]+ - Synthesis and StructureO,O′-Diethyl thiocarbonate and bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide dissolved in 1,2-dimethoxyethane, react below 0°C to give ethoxy trimethylsilane and tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide - [P≡C—S]- [Li(dme)3]+ - (1a). Apart from bis(trimethylsilyl)sulfane or carbon oxide sulfide, dark red concentrated solutions of λ3-phosphaalkyne 1 are also obtained from reactions of carbon disulfide with bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide or with the homologous lithoxy-methylidynephosphane (2) [1]. The ir spectrum shows two absorptions at 1762 and 747 cm-1 characteristic for the P≡C and C—S stretching vibrations. The nmr parameters {δ(31P) - 121.3; δ(13C) 190.8 ppm; 1JCP 18.2 Hz} resemble much more values of diorganylamino-2λ3-phosphaalkynes than those of bis(1,2-dimethoxyethane-O,O′)lithoxy-methylidyne-phosphane (2a). As found by an X-ray structure analysis (P21/c; a = 1192.6(16); b = 1239.1(19); c = 1414.8(26) pm; β = 105.91(13)° at -100 ± 3°C; Z = 4 formula units; wR = 0.064) of pale yellow crystals (mp. + 16°C) isolated from the reaction with O,O′-diethyl thiocarbonate, the solid is built up of separate [P≡C—S]- and [Li(dme)3]+ ions. Typical bond lengths and angles are: P≡C 155.5(11); C—S 162.0(11); Li—O 206.4(17) to 220.3(20) pm; P≡C—S 178.9(7)°.
    Notes: O,O′-Diethylthiocarbonat setzt sich mit Bis-(tetrahydrofuran)lithium-bis(trimethylsilyl)phosphanid in 1,2-Dimethoxyethan unterhalb 0°C zu Ethoxy-trimethylsilan und Tris(1,2-dimethoxyethan-O,O′)lithium-2λ3-phosphaethinylsulfanid - [P≡C—S]-[Li(dme)3]+ - (1a)1,2-Dimethoxyethan (dme); Tetrahydrofuran (thf); Bis(2-methoxyethyl)ether (diglyme). Den λ3-Phosphaalkinen P≡C—S—Li und P≡C—O—Li werden unabhängig vom Gehalt an koordinierendem Solvens und der Konstitution die Ziffern 1 und 2 zugeordnet; bei den röntgenstrukturanalytisch untersuchten Komplexen [P≡C—S]-[Li(dme)3]+ und P≡C—O—Li(dme)2 kommt das Suffix a hinzu. um. Das als dunkelrote, konzentrierte Lösung erhaltene λ3-Phosphaalkin 1 entsteht neben Bis(trimethylsilyl)sulfan bzw. Kohlenstoffoxidsulfid auch bei den Umsetzungen von Kohlenstoffdisulfid mit Bis(tetrahydrofuran)lithium-bis(trimethylsilyl)phosphanid oder dem homologen Lithoxy-methylidinphosphan P≡C—O—Li (2) [1]. Das IR-Spektrum weist die für eine P≡C- und C—S-Valenzschwingung charakteristischen Absorptionen bei 1762 und 747 cm-1 auf; die NMR-Parameter {δ(31P) - 121,3; δ(13C) 190,8 ppm; 1JCP 18,2 Hz} gleichen mehr den Werten der Diorganylamino-2λ3-phosphaalkine als des Bis(1,2-dimethoxyethan-O,O′)-lithoxy-methylidinphosphans (2a). Nach den Ergebnissen einer Röntgenstrukturanalyse (P21/c; a = 1192,6(16); b = 1239,1(19); c = 1414,8(26) pm; β = 105,91(13)° bei -100 ± 3°C; Z = 4 Formeleinheiten; wR = 0,064) an blaßgelben, aus einem Ansatz mit O,O′-Diethylthiocarbonat isolierten Kristallen (Schmp. + 16°C) liegen im Festkörper getrennte [P≡C—S]-- und [Li(dme)3]+-Ionen vor. Charakteristische Bindungslängen und -winkel sind: P≡C 155,5(11); C—S 162,0(11); Li—O 206,4(17) bis 220,3(20) pm; P≡C—S 178,9(7)°.
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    Pr(CH3COO)3, ein wasserfreies Selten-Erd-Acetat mit Netzwerkstruktur (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 438-443 
    Details
    ISSN: 0044-2313
    Keywords: Praseodymium(III) Acetate ; Synthesis ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pr(CH3COO)3, an Anhydrous Rare-Earth Acetate with a Network StructurePr(CH3COO)3 may be prepared by dehydration of Pr(CH3COO)3 · 1,5 H2O at 180°C as an amorphous green powder. Single crystals were grown from the powder by addition of (NH4)CH3COO as „mineralisator“ at 180°C in a sealed glass ampoule. The crystal structure (tetragonal, P421c (no. 114), Z = 24, a = 2106.5(3), c = 1323.6(1) pm, Vm = 147.39(3) cm3/mol, R = 0.055, Rw = 0.029) was determined from four-circle-diffractometer data. The Pr3+ ions occupy three crystallographically independent positions and are surrounded by 9 and 10 oxygen atoms, respectively. Acetate ions connect the cations to a complicated three-dimensional network.
    Notes: Pr(CH3COO)3 entsteht beim Entwässern von Pr(CH3COO)3 · 1,5 H2O bei 180°C als amorphes Pulver. Einkristalle konnten daraus mit Hilfe von (NH4)CH3COO als „Mineralisator“ ebenfalls bei 180°C in einer geschlossenen Glasampulle gezüchtet werden. Die Kristallstruktur (tetragonal, P421c (Nr. 114), Z = 24, a = 2106,5(3), c = 1323,6(1) pm, Vm = 147,39(3) cm3/mol, R = 0,055, Rw = 0,029) wurde anhand von Vierkreis-Diffraktometerdaten bestimmt. Pr3+-Ionen besetzen drei unterschiedliche kristallographische Positionen und sind von 9 bzw. 10 Sauerstoffatomen umgeben. Acetationen verbinden die Kationen auf unterschiedliche Weise zu einem komplizierten dreidimensionalen Netzwerk.
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    Die Chloride Na3xM2-xCl6 (M = La—Sm) und NaM2Cl6 (M = Nd, Sm): Derivate des UCl3-Typs. Synthese, Kristallstruktur und Röntgenabsorptionsspektroskopie (XANES) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 444-450 
    Details
    ISSN: 0044-2313
    Keywords: Chlorides ; lanthanides ; synthesis ; crystal structure ; X-ray absorption spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Chlorides Na3xM2-xCl6 (M = La—Sm) and NaM2Cl6 (M = Nd, Sm): Derivatives of the UCl3-Type of Structure. Synthesis, Crystal Structure and X-Ray Absorption Spectroscopy (XANES)Single crystals of the derivatives of the UCl3-type structure Na3xM2-xCl6 (M = La/x = 0.364(4); Ce/0.349(5); Pr/0.318(8); Nd/0.305(5); Sm/0.246(4)) and NaSm2Cl6 were grown by different methods generally under reducing conditions. They are addition [Na(Sm2)Cl6] and addition/substitution variants [Na2x(NaxM2-x)Cl6] of the UCl3 structure type [□(U2)Cl6]. X-Ray Absorption Spectroscopy (XANES) at the LIII edge characterizes NaSm2Cl6 and NaNd2Cl6 as mixed-valence compounds with valences of +2 and +3 in statistical distribution (approximately 1:1) for Sm and Nd, respectively.
    Notes: Einkristalle der Derivate des UCl3-Typs Na3xM2-xCl6 (M = La/x = 0,364(4); Ce/0,349(5); Pr/0,318(8); Nd/0,305(5); Sm/0,246(4)) sowie von NaSm2Cl6 wurden auf unterschiedlichen Wegen, im allgemeinen unter reduzierenden Bedingungen erhalten. Sie sind Additions- [Na(Sm2)Cl6] bzw. Additions- / Substitutionsvarianten [Na2x(NaxM2-x)Cl6] des UCl3-Strukturtyps [□(U2)Cl6]. Röntgenabsorptionsspektren (XANES) an der Lm-Kante charakterisieren NaSm2Cl6 und NaNd2Cl6 als gemischtvalente Verbindungen mit Valenzen von +2 und +3 in statistischer Verteilung (etwa 1:1) für Sm bzw. Nd.
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    Synthesis, structures and luminescence of two new Europium(II) Silicate-Chlorides, Eu2SiO3Cl2 and Eu5SiO4Cl6 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 451-456 
    Details
    ISSN: 0044-2313
    Keywords: Silicates ; crystal structure ; europium ; luminescence ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Strukturen und Lumineszenz von zwei neuen Europium(II)-silicat-chloriden, Eu2SiO3Cl2 und Eu5SiO4Cl6Eu2SiO3Cl2 und Eu5SiO4Cl6 wurden durch Erhitzen von EuCl2 mit EuSiO3 bzw. Eu2SiO4 gewonnen, Sr2SiO3Cl2:Eu2+ aus einem Gemenge von SrCO3, Eu2O3, SrCl2 · 6H2O und SiO2 unter reduzierenden Bedingungen. Die Kristallstrukturen von Eu2SiO3Cl2 [a = 1118,7(5), c = 952,6(1) pm, tetragonal, I4/m, Z = 8, R = 3,3, Rw = 3,0%] und Eu5SiO4Cl6 [a = 900,4(1), b = 1401,7(2), c = 1112,3(2) pm, β = 103,51(1)°, monoklin, C2/c, Z = 4, R = 3,6, Rw = 2,6%] wurden aus Einkristall-Vierkreisdiffraktometer-Daten bestimmt und mit verwandten Verbindungen verglichen. Die Lumineszenzeigenschaften wurden bei 300 K und bei 4,2 K untersucht; sämtliche Verbindungen zeigen eine intensive blaugrüne Photolumineszenz. Sr2SiO3Cl2:Eu2+ zeigt Thermolumineszenz.
    Notes: Eu2SiO3Cl2 and Eu5SiO4Cl6 were prepared by reaction of EuCl2 with EuSiO3 and Eu2SiO4, respectively, Sr2SiO3Cl2: Eu2+ from mixtures of SrCO3, Eu2O3, SrCl2 · 6H2O and SiO2 under reducing conditions. The crystal structures of Eu2SiO3Cl2 [a = 1118.7(5), c = 952.6(1) pm, tetragonal, I4/m, Z = 8, R = 3.3, Rw = 3.0%] and Eu5SiO4Cl6 [a = 900.4(1), b = 1401.7(2), c = 1112.3(2) pm, β = 103.51(1)°, monoclinic, C2/c, Z = 4, R = 3.6, Rw = 2.6%] were determined from four-circle diffractometer data and compared with related compounds. The luminescence properties were investigated at 300 K and at 4.2 K; all compounds show intense bluish-green photoluminescence. Sr2SiO3Cl2:Eu2+ shows thermoluminescence.
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    Synthetic and structural Studies on Organomolybdenum-Bismuth Halide Complexes (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 457-466 
    Details
    ISSN: 0044-2313
    Keywords: Organomolybdenum-bismuth halide complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Untersuchungen zur Synthese und Struktur von Organomolybdän-Bismuthalogenid-KomplexenDie Reaktionen von BiBr2Ph mit Na/K[Mo(CO)3(η—C5H5)], von [BiPh{Mo(CO)3(η—C5H5)}2] mit BiBr2Ph oder BiBr3 und BiPh3 mit [Bi{Mo(CO)3(η—C5H5)}3] ergeben den Komplex [BiBrPh{Mo(CO)3(η—C5H5)}] 1, der röntgenographisch charakterisiert worden ist. Der Komplex 1 besteht aus einem Bismutzentrum mit einem Bromatom, einer Phenylgruppe und einer Mo(CO)3(η—C5H5)-Einheit. Eine intermolekulare Wechselwirkung besteht zum Bromatom eines benachbarten Moleküls, wodurch sich eine eindimensionale polymere Struktur ergibt. Bei der Umsetzung mit einer Bromidabgebenden Verbindung wird zunächst der anionische Komplex [BiBr2Ph{Mo(CO)3(η—C5H5)}2]- 3- und bei längerer Reaktion [BiBr2{Mo(CO)3(η—C5H5)}2]- 5- gebildet, das als [Ph4P]+-Salz röntgenographisch charakterisiert wurde. Der Komplex 5-, der am Bi zwei Br und zwei Mo(CO)3(η—C5H5)-Einheiten enthält, liegt in einer Struktur zwischen unvollständig trigonal-pyramidal und tetraedrisch vor. Der Komplex [PPN]2[Bi2Cl6{Mo(CO)3(η—C5H5)}2] 8 wurde ebenfalls dargestellt und röntgenographisch charakterisiert. Es liegt ein dimeres Anion vor, das aus zwei quadratischen Pyramiden mit einer gemeinsamen Kante besteht, in denen die Chloratome in der Basisebene und die zwei Mo(CO)3(η—C5H5)-Einheiten sich an den Spitzen in gegenüberliegenden Positionen befinden.
    Notes: The reactions between either BiBr2Ph and Na/K[Mo(CO)3(η—C5H5)], [BiPh{Mo(CO)3(η—C5H5)}2] and BiBr2Ph, or BiBr3 and BiPh3 and [Bi{Mo(CO)3(η—C5H5)}3] afford the complex [BiBrPh{Mo(CO)3(η—C5H5)}] 1 which has been characterised by X-ray crystallography. Complex 1 comprises a bismuth centre bonded to a bromine atom, a phenyl group and a Mo(CO)3(η—C5H5) fragment together with a longer secondary intermolecular interaction between a bromine from an adjacent molecule which results in a one-dimensional polymeric structure. Addition of a source of bromide anion to 1 affords the anionic complex [BiBr2Ph{Mo(CO)3(η—C5H5)}]- 3- although prolonged reaction results in the complex [BiBr2{Mo(CO)3(η—C5H5)}2]- 5- which was characterised by X-ray crystallography as its [Ph4P]+ salt. Complex 5- comprises a mononuclear bismuth centre bonded to two bromine atoms and two Mo(CO)3(η—C5H5) fragments in a geometry which lies between equatorially vacant trigonal bipyramidal and tetrahedral. The complex [PPN]2[Bi2Cl6{Mo(CO)3(η—C5H5)}2] 8 has also been synthesised and characterised by X-ray crystallography. A dimeric dianion is observed which can be viewed as two edge-shared square-based pyramids with chlorine atoms in the basal planes and Mo(CO)3(η—C5H5) fragments in the apical positions on opposite sides of the Bi2Cl6 plane.
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    The Molybdenum Stannide MoSn2In memoriam Konrad Schubert (1915-1992) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 467-470 
    Details
    ISSN: 0044-2313
    Keywords: MoSn2 ; crystal structure ; Pauli paramagnetism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Das Molybdän-Stannid MoSn2Die Titelverbindung wurde durch Tempern von Molybdän-Pulver mit einem Überschuß von Zinn hergestellt. Einkristalle wurden durch Auflösen der zinnreichen Matrix in Salzsäure erhalten. Sie sind Pauli-paramagnetisch. Die Kristallstruktur wurde aus Einkristall-Röntgen-Diffraktometer-Daten bestimmt: P6222, a = 548,8(1) pm, c = 1417,1(2) pm, Z = 6, R = 0,036 für 18 variable Parameter und 389 Strukturfaktoren. MoSn2 ist erst der zweite Vertreter der hexagonalen Mg2Ni-Struktur. Die Beziehung der Struktur zum CuAl2-Typ wird diskutiert.
    Notes: The title compound was prepared by annealing molybdenum powder with an excess of tin. Single-crystals were obtained by dissolving the tin-rich matrix in hydrochloric acid. They are Pauli paramagnetic. The crystal structure was determined from single-crystal X-ray diffractometer data: P6222, a = 548.8(1) pm, c = 1417.1(2) pm, Z = 6, R = 0.036 for 18 variable parameters and 389 structure factors. MoSn2 is only the second representative of the hexagonal Mg2Ni-type structure. The relation of the structure to the CuAl2-type is discussed.
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    Spektroskopische und röntgenographische Untersuchungen an Dichlormethyl-QuecksilberverbindungenProfessor Wolfgang Sawodny zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 625-631 
    Details
    ISSN: 0044-2313
    Keywords: Bis(dichloromethyl)mercury ; Dichloromethylmercuryalkyles ; synthesis ; NMR, vibrational spectra ; X-ray structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Spectroscopic and X-Ray Structural Investigations on Dichloromethyl Mercury CompoundsBis(dichloromethyl)mercury, Hg(CHCl2)2, and mixed alkyl compounds RHgCHCl2 (with R = CH3, C2H5) have been synthesized by known methods from CH2Cl2, lithium butanide and HgCl2, CH3HgCl or C2H5HgCl, respectively. The 1H-, 13C-NMR as well as the IR and Raman spectra of the liquid alkyls RHgCHCl2 and the high melting Hg(CHCl2)2 have been measured and assigned. According to the X-ray structure determination Hg(CHCl2)2 crystallizes in the monoclinic space group P21/c with 4 non-symmetric molecules per unit cell (R = 0.046).
    Notes: Bis(dichlormethyl)quecksilber, Hg(CHCl2)2, und die gemischten Alkylverbindungen RHgCHCl2 (mit R = CH3, C2H5) werden nach bekannten Vorschriften aus CH2Cl2, Lithiumbutanid und HgCl2 bzw. CH3HgCl oder C2H5HgCl synthetisiert. Die 1H- und 13C-NMR- sowie die IR- und Ramanspektren der flüssigen Alkyle RHgCHCl2 und des hochschmelzenden Hg(CHCl2)2 werden registriert und ausgewertet. Nach der Röntgenstrukturanalyse kristallisiert Hg(CHCl2)2 in der monoklinen Raumgruppe P21/c mit 4 azentrischen Molekülen in der Elementarzelle (R = 0,046).
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    Darstellung von μ-Schwefeldisulfoniumsalzen [(CH3)2S—Sx—S(CH3)2]2+2A- (x = 1-3, A- = AsF6-, SbF6-, SbCl6-). Über die Analogie im Reaktionsverhalten zwischen Sulfanen und SulfoniumsalzenProfessor Wolfgang Sawodny zum 60. Geburtstag gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 632-637 
    Details
    ISSN: 0044-2313
    Keywords: μ-Sulfurdisulfonium salts ; preparation ; single crystal X-ray structure ; Raman, NMR spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of μ-Sulfurdisulfonium Salts [(CH3)2S—Sx—S(CH3)2]2+2A- (x = 1-3, A- = AsF6-, SbF6-, SbCl6-). On the Analogy of the Reactivity of Sulfanes and Sulfonium SaltsThe preparation of the μ-sulfurdisulfonium salts [(CH3)2S—Sx—S(CH3)2]2+(A-)2 with x = 1-3 and A- = AsF6-, SbF6-, SbCl6- is reported. The salts are formed by reaction of (CH3)2SH+A- and (CH3)2SSH+A- with SCl2 and S2Cl2, resp. They are characterized by vibrational spectroscopic measurements. [(CH3)2S—S2—S(CH3)2]2+(SbF6-)2 crystallizes in the space group C2/c with a = 1 884.5(7) pm, b = 1 302.8(5) pm, c = 1 477.2(5) pm, β = 98.62(3)° und Z = 8.
    Notes: Es wird über die Darstellung der μ-Schwefeldisulfoniumsalze [(CH3)2S—Sx—S(CH3)2]2+ (A-)2 mit x = 1-3 und A- = AsF6-, SbF6-, SbCl6- berichtet. Die Salze werden durch Kondensationsreaktionen von (CH3)2SH+A- und (CH3)2SSH+A- mit SCl2 bzw. S2Cl2 gebildet. Ihre Charakterisierung erfolgt schwingungsspektroskopisch. Das [(CH3)2S—S2—S(CH3)2]2+(SbF6-)2 kristallisiert in der Raumgruppe C2/c mit a = 1 884,5(7) pm, b = 1 302,8(5) pm, c = 1 477,2(5) pm, β = 98,62(3)° und Z = 8.
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    Über die Reaktion von HCl im System HF/SbF5 und die Kristallstruktur von SbCl3F2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 638-641 
    Details
    ISSN: 0044-2313
    Keywords: Stibiumtrichlorodifluoride ; Crystal Structure ; Raman Spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reaction of HCl with HF/SbF5 and the Crystal Structure of SbCl3F2The reaction of HCl in HF/SbF5 solution at -78°C yields H2F+SbClF5-. At -40°C formation of SbCl3F2 was observed, which crystallizes in the tetragonal space group I-4 with a = 1 281.6(5) pm, c = 758.1(6) pm with 8 formula units per unit cell. The structure contains cis-fluorine-bridged tetramers, in which Sb has a distorted octahedral coordination.
    Notes: Die Reaktion von HCl mit einer HF/SbF5 Lösung ergibt bei -78°C H2F+SbClF5-. Bei -40°C wird die Bildung von SbCl3F2 beobachtet. Es kristallisiert in der tetragonalen Raumgruppe I-4 mit a = 1 281,6(5) pm, c = 758,1(6) pm und Z = 8. Die Struktur enthält cis-Fluor-verbrückte Tetramere, in denen Antimon eine verzerrt oktaedrische Koordinationssphäre hat.
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  • 81
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    Zur Kristallchemie der Kupfer-Lanthanoid-Oxowolframate: (I) triklin-α-CuTbW2O8, (II) monoklin-CuInW2O8 und (III) monoklin-CuYW2O8 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 642-646 
    Details
    ISSN: 0044-2313
    Keywords: Copper, rare earth, tungsten, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Chemistry of Copper Rare-Earth Oxotungstates: (I): triclinic-α-CuTbW2O8, (II): monoclinic-CuInW2O8 and (III): monoclinic-CuYW2O8Single crystals of (I), (II) and (III) were prepared by recrystallisation in closed systems and examined by X-ray technique. (I): space group Cil—P1, a = 7.3080, b = 7.8945, c = 7.1476 Å, α = 115.23, β = 116.21, γ = 56.98°, Z = 2; (II): space group C2h6—C2/c, a = 9.6576, b = 11.6496, c = 4.9863 Å, β = 91.17°, Z = 4; (III): space group C2h4—P2/n, a = 10.0504, b = 5.8214, c = 5.0224 Å, β = 94.23°, Z = 2. The crystal structures are discussed with respect to calculations of the coulombterms of lattice energy and possible valence states of Cu2+ and Mo5+.
    Notes: Einkristalle von (I), (II) und (III) wurden durch Rekristallisation in geschlossenen Systemen dargestellt und röntgenographisch untersucht. Die kristallographischen Daten lauten: (I): Raumgruppe Cil—P1, a = 7,3080, b = 7,8945, c = 7,1476 Å, α = 115,23, β = 116,21, γ = 56,98°, Z = 2; (II): Raumgruppe C2h6—C2/c, a = 9,6576, b = 11,6496, c = 4,9863 Å, β = 91,17°, Z = 4; (III): Raumgruppe C2h4—P2/n, a = 10,0504, b = 5,8214, c = 5,0224 Å, β = 94,23°, Z = 2. Die Kristallstrukturen werden mit Blick auf Berechnungen der Coulombterme der Gitterenergie und mögliche Ladungen von Cu2+ und Mo5+ diskutiert.
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    Zur Kenntnis eines Barium-Kupfer-Orthoarsenats: BaCu2(AsO4)2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 651-654 
    Details
    ISSN: 0044-2313
    Keywords: Barium, copper, arsenic, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Structure of Barium-Copper-Orthoarsenate BaCu2(AsO4)2Single crystals of BaCu2(AsO4)2 were prepared above 1 000°C by CO2-LASER technique and investigated by X-ray structure determination. The light blue crystals show monoclinic symmetry, space group C2h5—P21/n, a = 4.752; b = 8.506; c = 8.945 Å; β = 93.49°, Z = 2. BaCu2(AsO4)2 represents a hitherto unknown structure type with Cu2+ in trigonal bipyramidal coordination. Ba2+ shows an 8 + 2 surrounding by O2- and As5+ is tetrahedrally coordinated. The crystal structure is discussed with respect to related orthophosphates and vanadates.
    Notes: Mit CO2-LASER-Technik wurden bei ca. 1 000°C Einkristalle der Verbindung BaCu2(AsO4)2 dargestellt und röntgenographisch untersucht. Die blaßblauen Kristalle haben monokline Symmetrie, Raumgruppe C2h5—P21/n, mit a = 4,752; b = 8,506; c = 8,945 Å; β = 93,49°, Z = 2. BaCu2(AsO4)2 repräsentiert einen neuen Strukturtyp, der Cu2+ in trigonal bipyramidaler Koordination zeigt. Ba2+ ist 8 + 2-fach und As5+ tetraedrisch von Sauerstoff umgeben. Die Kristallstruktur wird unter Bezug auf verwandte Orthophosphate und -vanadate diskutiert.
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    Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Decahalogenoditechnetate(IV), [Tc2X10]2-, X = Cl, Br (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 655-658 
    Details
    ISSN: 0044-2313
    Keywords: Decachloroditechnetate(IV) ; Decabromoditechnetate(IV) ; Synthesis ; Raman, IR Spectra ; Normal Coordinate Analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation, Vibrational Spectra and Normal Coordinate Analysis of Decahalogenoditechnetates(IV), [Tc2X10]2-, X = Cl, BrThe reaction of [TcX6]2-, X = Cl, Br, with trifluoroacetic acid yield at room temperature the edge-sharing bioctahedral anions [Tc2X10]2-, which IR and Raman spectra are assigned according to point group D2h. Using the crystal data of isostructural osmium complexes a normal coordinate analysis based on a general valence force field has been performed for [Tc2X10]2-, revealing a good agreement of the calculated frequencies with the bands observed in the IR and Raman spectra. The stronger bonding of the terminal as compared to the bridging ligands is shown by the valence force constants, fd(TcXt) 〉 Fd(TcXb).
    Notes: [TcX6]2-, X = Cl,Br, reagiert bei Raumtemperatur mit Trifluoressigsäure unter Bildung der kantenverknüpften Dioktaederanionen [Tc2X10]2-, deren IR- und Raman-Spektren entsprechend der Punktgruppe D2h zugeordnet werden. Basierend auf den kristallographischen Daten isostruktureller Osmiumkomplexe und unter Verwendung des allgemeinen Valenzkraftfeldes, werden für Decachloro- und Decabromodi-technetat(IV) Normalkoordinatenanalysen durchgeführt, die eine gute Übereinstimmung der berechneten Frequenzen mit den beobachteten Banden aus den IR- und Raman-Spektren ergeben. Die festere Bindung terminaler im Vergleich zu verbrückenden Liganden spiegelt sich in den Valenzkraftkonstanten wider: fd(TcXt) 〉 fd(TcXb).
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    Zur Kenntnis ‘Kationen-reicher’ Tantalate Über Li7[TaO6] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 659-664 
    Details
    ISSN: 0044-2313
    Keywords: Tantalate Li7[TaO6] ; Single Crystals ; Crystal Structure ; MAPLE ; Charge Distribution ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Tantalates ‘rich in Cations’ On Li7[TaO6]For the first time, colourless single crystals of Li7[TaO6] were grown by annealing intimate mixtures of Li2O and Ta2O5 (Li:Ta = 7,7:1) in closed Ni-cylinders (1 000°C, 156 d). [Trigonal-rhomboedral with a = 535.8(1) pm, c = 1 507.3(3) pm, c/a = 2.81/Guinier-Simon-powder data; Z = 3. Space group R3 for the part Li(1)6TaO6 and presumably P3 for Li7TaO6, including Li(2)].The crystal structure was solved by four-cycle-diffractometer data [Mo—Kα, 331 from 331 Io(hkl), R = 1.99%, Rw = 1.96%], parameters see text.The positions of anions correspond to the motif of a hexagonal closest packing of spheres, obviously deformed (with MEFIR of O2- space filling corresponds to 69.8% instead of expected 73.2%. 1/3 of the octahedron holes are ordered occupied by Ta and Li(2), 1/2 of the tetrahedral holes likewise ordered by Li(1). All polyhedra of coordination of the anions are trigonal prisms.The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, as well as charge distribution ‘CHARDI’ are calculated and discussed.
    Notes: Erstmals wurden farblose Einkristalle von Li7[TaO6] durch Tempern inniger Gemenge von Li2O und Ta2O5 (Li:Ta = 7,7:1) in einem verschlossenen Ni-Zylinder (1 000°C, 156 d) dargestellt trigonal-rhomboedrisch; a = 535,8(1) pm, c = 1 507,3(3) pm, c/a = 2,81/Guinier-Simon-Pulverdaten; Z = 3. Raumgruppe R3 für den Li(1)6TaO6-Teil; vermutlich P3 für Li(1)6Li(2)1[TaO6].Die Kristallstruktur wurde mittels Vierkreisdiffraktometerdaten [Mo—Kα, 331 von 331 Io(hkl), R = 1,99%, Rw = 1,96%] bestimmt, Parameter siehe Text.Es liegt bezüglich der Anionen im Prinzip das Motiv einer hexagonal-dichtesten Kugelpackung vor; die Verzerrung ist deutlich mit MEFIR(O2-) = 154,3 pm beträgt die Raumerfüllung 69,8% statt ideal 73,2%). Es sind 2 der 6 Oktaeder- (mit Ta bzw. Li(2)) und 6 der 12 Tetrederlücken mit Li(1) besetzt. Alle Koordinationspolyeder um O sind trigonale Prismen.Der Madelunganteil der Gitterenergie, MAPLE, und Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, sowie die Ladungsverteilung ‘CHARDI’ wurden berechnet und diskutiert.
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    Hydrate des Cer(III)-chlorids (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 665-671 
    Details
    ISSN: 0044-2313
    Keywords: Cerium(III) chloride hydrates ; Synthesis ; Solution enthalpies ; Crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrates of Cerium(III) ChlorideThe thermal dehydration of CeCl3 · 7 H2O to CeCl3 gives four definite intermediates: CeCl3 · 6 H2O, CeCl3 · 3 H2O, CeCl3 · 2 H2O, CeCl3 · H2O. In the hexahydrate monomeric [CeCl2(H2O)6]+ units exist. A structure analysis of CeCl3 · 3 H2O gave an orthorhombic unit cell (S.G. Pnma; Z = 4) with a = 1 242.7(4) pm; b = 881.8(8) pm, c = 693.4(5) pm. The structure consists of [CeCl4/2Cl(H2O)3] chains, where two Ce3+ ions are connected via two chloride ions, forming bent chains in the [010] direction. The trihydrates LnCl3 · 3 H2O (Ln = Pr—Tb) are isotypic, also one modification of LaCl3 · 3 H2O. The structures of the di- and mono-hydrate are not yet known. Molar volumina and solution enthalpies in water vary linearly with the number of H2O molecules per formula unit.
    Notes: Der thermische Abbau von CeCl3 · 7 H2O zu CeCl3 verläuft über die präparativ faßbaren Hydrate CeCl3 · 6 H2O, CeCl3 · 3 H2O, CeCl3 · 2 H2O und CeCl3 · H2O. CeCl3 · 6 H2O kristallisiert isotyp zu PrCl3 · 6 H2O mit monomeren [CeCl2(H2O)6]+-Einheiten. Eine Strukturbestimmung von CeCl3 · 3 H2O Pnma; Z = 4; a = 1 242,7(4) pm; b = 881,8(8) pm, c = 693,4(5) pm ergab das Vorliegen von [CeCl4/2Cl(H2O)3]-Einheiten, die über je zwei Chlorid-Doppelbrücken zu gewinkelten Ketten in [010]-Richtung verknüpft sind. Die Trihydrate LnCl3 · 3 H2O (Ln = Pr—Tb) sind isotyp, ebenfalls eine Modifikation von LaCl3 · 3 H2O. Die Strukturen des Di- und Monohydrats sind noch unbekannt. Die Molvolumina und Lösungsenthalpien in Wasser ändern sich linear mit dem Hydratationsgrad.
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    Beiträge zum thermischen Verhalten von Sulfaten. XII. Zum chemischen Transport von In2(SO4)3 mit Cl2 und mit HCl. Experimente und ModellrechnungenProfessor Heinz Dieter Lutz zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 672-681 
    Details
    ISSN: 0044-2313
    Keywords: Chemical transport ; In2(SO4)3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions on the Thermal Behaviour of Sulfates XII. The Chemical Vapour Transport of In2(SO4)3 with Cl2 and HCl. Experimental Results and CalculationsBy means of CVT (T1 between 500°C and 825°C; ΔT = 50°C), well shaped crystals of anhydrous In2(SO4)3 can be grown in the less hot region of a closed silica ampoule. We investigated the dependence of the deposition rate on the variation of the concentration of the transport agent (system In2(SO4)3/Cl2) and on the variation of the transport temperature (In2(SO4)3/Cl2 as well as In2(SO4)3/HCl).A comparison of the experimental results with thermodynamical calculations shows a satisfying agreement. The influence of the variation of some additional parameters (H2O from the wall of the ampoule; ΔBH2980(In2(SO4)3)) on the deposition rate is discussed.
    Notes: Chemische Transportexperimente im Temperaturgradienten (500°C ≤ T1 ≤ 825°C; T2 〉 T1; ΔT = 50°C) ermöglichten es, gut ausgebildete Kristalle von wasserfreiem In2(SO4)3 in der weniger heißen Zone einer geschlossenen Quarzampulle phasenrein abzuscheiden. Der Einfluß einer Variation der Transportmittelkonzentration (C(Cl2)) (Cl2 eingesetzt als PtCl2)) sowie der mittleren Transporttemperatur (T̄ = 0,5 · (T2 + T1)) auf die Transportrate wurde untersucht. Weiterhin wurden Experimente mit dem Transportmittel HCl bei unterschiedlichem T̄ durchgeführt.Die Beobachtungen lassen sich durch thermodynamische Modellrechnungen befriedigend wiedergeben. Der Einfluß einer Variation weiterer Parameter (H2O aus der Ampullenwand; ΔBH2980(In2(SO4)3) auf die berechneten Transportraten wird diskutiert.
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    Synthese, Eigenschaften und Kristallstrukturen von Magnesium-Diazadien-Komplexen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 691-696 
    Details
    ISSN: 0044-2313
    Keywords: Magnesium complexes ; diazadiene ligands ; radical anions ; endiamides ; X-ray structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Properties and Crystal Structures of Magnesium Diazadiene ComplexesReactions of phenyl-substituted 1,4-diaza-1,3-butadienes (DAD) RN=CPh—CPh=NR (R = C6H5) 1a, C6H4-4-CH3 1b, C6H4-4-OCH3 (1c) with magnesium in dimethoxyethan lead to complexes of the type [Mg(DAD)2(DME)] 2a-c, with DAD ligands in form of radical anions. Furthermore, highly reactiv complexes of the composition [Mg(DAD)(DME)2] 3a-c could be obtained. The crystal structures of 2a, 3a and 3c were determined.
    Notes: Die Reaktion phenylsubstituierter 1,4-Diaza-1,3-butadiene (DAD) RN=CPh—CPh=NR (R = C6H5 1a, C6H4-4-CH3 1b, C6H4-4-OCH3 1c) mit Magnesium in Dimethoxyethan (DME) führt zu Verbindungen des Typs [Mg(DAD)2(DME)] 2a-c, in denen die DAD-Liganden als Radikalanionen gebunden sind. Außerdem enstehen äußerst reaktive Komplexe der Zusammensetzung [Mg(DAD)(DME)2] 3a-c. Die Kristallstrukturen von 2a, 3a und 3c wurden aufgeklärt.
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    High-spin Mangan(II)-Phthalocyanine: Darstellung und spektroskopische Eigenschaften von Acidophthalocyaninatomanganat(II) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 682-690 
    Details
    ISSN: 0044-2313
    Keywords: Phthalocyanines ; MnII complex ; Uv-vis-n.i.r., m.i.r., f.i.r., resonance Raman, ESR spectra ; magnetism ; cyclovoltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: High Spin Manganese(II) Phthalocyanines: Preparation and Spectroscopical Properties of Acidophthalocyaninatomanganate(II)Acidophthalocyaninatomanaganese(III) is reduced by boranate, thioacetate or hydrogensulfide to yield acidophthalo-cyaninatomanganate(II) ([Mn(X)Pc2-]-; X = Cl, Br, NCO, NCS) being isolated as tetra(n-butyl)ammonium salt. In the cyclovoltammogram of [Mn(NCO)Pc2-]- the halv-wave potential for the redoxcouple MnII/MnIII is at -0.13 V, that of the first ring reduction at -0.99 V. The magnetic moments are indicative of high-spin 6A1 ground states: μMn = 5.84 (NCO), 5.78(Cl), 5.65 (Br), 5.68 μB (NCS). A Curie-like temperature dependence of μMn is observed in the region 300-30 K. Below 30 K an increase in μMn occurs due to weak intermolecular ferromagnetic coupling. The ESR spectra confirm the S = 5/2 ground state with a strong g = 6 resonance observed (AMn = 80 G) as expected for an axially distorted ligand-field. Besides the typical π-π* transitions of the Pc2--ligand several weak bands are observed in the Uv-vis-n.i.r. spectra at ca. 7.5, 9.1, 14.0 and 19.0 kK that are assigned to trip-multiplet transitions. In resonance with the band at 19.0 kK the Mn—X stretching vibration (v(MnX)) is resonance Raman enhanced: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm-1. These vibrational frequencies are confirmed by the f.i.r. spectra. In the case of the thiocyanato-complex probably both forms of bonding of the ambident NCS-ligand are present (v(Mn—NCS): 274 cm-1). The frequencies of the vibrations of the inner (CN)8 ring are reduced by up to 20 cm-1 as compared with those of low spin MnII phthalocyanines.
    Notes: Acidophthalocyaninatomanagan(III) wird mittels Boranat, Thioacetat oder Hydrogensulfid zum Acidophthalocyaninatomanganat(II) ([Mn(X)Pc2]; X = Cl, Br, NCO, NCS) reduziert und als Tetra(n-butyl)ammoniumsalz isoliert. Im Cyclovoltammogramm von [Mn(NCO)Pc2-]- liegt das Halbstufenpotential für das Redoxpaar MnII/MnIII bei -0,13 V, das der ersten Ringreduktion bei -0,99 V. Die magnetischen Momente der Komplexe weisen auf einen high-spin 6A1-Grundzustand hin: μMn = 5,84 (NCO), 5,78 (Cl), 5,65 (Br), 5,68 μB (NCS). Die Temperaturabhängigkeit der magnetischen Suszeptibilität μMn zeigt zwischen 300 und 30 K Curie-Verhalten. Unterhalb von 30 K steigt μMn wegen schwacher intermolekularer ferromagnetischer Kopplungen an. Die ESR-Spektren bestätigen den S = 5/2-Grundzustand mit einem starken g = 6 Resonanzsignal (AMn = 80 G), wie es für ein axial verzerrtes Ligandenfeld erwartet wird. In den UV-VIS-NIR-Spektren treten neben den typischen π-π*-Übergängen des Pc2--Liganden weitere schwache Banden bei ca. 7,5, 9,1, 14,0 und 19,0 kK auf, die Trip-Multiplett-Übergängen zugeordnet werden. In den Resonanz-Raman-Spektren werden in Resonanz mit der Bande bei 19,0 kK bevorzugt die Mn—X-Valenzschwingungen (v(MnX)) angeregt: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm-1. Die Schwingungsfrequenzen stimmen mit entsprechenden FIR-Absorptionen gut überein. Im Falle des Thiocyanato-Komplexes sind eventuell beide Bindungsformen des ambidenten NCS-Liganden präsent (v(Mn—NCS): 274 cm-1). Die Schwingungsfrequenzen des inneren (CN)8-Ringes liegen um bis zu 20 cm-1 tiefer als die von low-spin MnII-Phthalocyaninen.
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    Li2H3IO6, eine neue Variante der Molybdänitstruktur (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 53-57 
    Details
    ISSN: 0044-2313
    Keywords: Dilithium trihydrogen orthoperiodate ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li2H3IO6, a New Variant of the Molybdenite StructureLi2H3IO6 crystallizes in P61 (a = 529.70(8), c = 2 759.6(5) pm; Z = 6). The crystals are twinned by merohedry, described by m ‖ [001] and 2 ⊥ [001]. According to the results of an X-ray structure determination (2 778 diffractometer data, Rw = 0.047), Li2H3IO6 exhibits a layer structure, with oxygen forming a distorted variant of the sulfur partial structure in molybdenite (MoS2), however, with iodine and lithium in the more (Li) or less (I) distorted octahedral holes. The Li2IO6 packages are connected via strong hydrogen bonds along the edges of distorted trigonal prisms.
    Notes: Li2H3IO6 kristallisiert in der Raumgruppe P61 (a = 529,70(8), c = 2 759,6(5) pm; Z = 6). Die Kristalle sind merohedrisch verviellingt, beschrieben durch m ‖ [001] und 2 ⊥ [001]. Nach der Röntgenstrukturanalyse (2 778 unabhängige Reflexe, Rw = 0,047) liegt eine Schichtstruktur vor, in der die Sauerstoffatome eine verzerrte Variante der Schwefelteilstruktur von Molybdänit (MoS2) ausbilden, die Kationen besetzen die mehr (Li) oder weniger (I) verzerrten Oktaederlücken. Die Li2IO6-Schichtpakete werden entlang der Kanten der verzerrten trigonalen Prismen durch Wasserstoffbrückenbindungen miteinander verknüpft.
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    Zur Reaktion von 2,2′-Dilithiumbiphenyl mit SmBr3 Die Struktur von [(C24H16)SmBr(thf)2]2 · [C24H14] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 703-706 
    Details
    ISSN: 0044-2313
    Keywords: SmIII dimeric complex ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reaction of Dilithiumbiphenyl with SmBr3. The Crystal Structure of [(C24H16)SmBr(thf)2]2 · [C24H14]In THF SmBr3 forms with [(biph)Li2] the dimeric complex [(quaph)SmBr(thf)2]2 · [C24H14]. The structure was characterized by X-ray single crystal structure analysis (space group P1 (No. 2), Z = 1, a = 943.3(6) pm, b = 1 350.3(1) pm, c = 1 599.9(9) pm, α = 64.99(5)°, β = 89.02(5)°, γ = 73.02(6)°). The Sm iones are bridged by two Br iones. Coordination by one quaph and THF ligands leads to distorded octahedra coordination of the Sm iones. Additionally crystallizes one molecule dibenzonaphthacene.
    Notes: SmBr3 reagiert mit [(biph)Li2] in THF zu dem zweikernigen Komplex [(quaph)SmBr(thf)2]2 · [C24H14]. Der Aufbau konnte durch eine Kristallstrukturanalyse geklärt werden (Raumgruppe P1 (Nr. 2), Z = 1, a = 943,3(6) pm, b = 1 350,3(1) pm, c = 1 599,9(9) pm, α = 64,99(5)°, β = 89,02(5)°, γ = 73,02(6)°). Die Sm-Ionen werden durch zwei Br-Ionen verbrückt. Durch zusätzliche Koordination eines quaph- und zweier THF-Liganden ist jedes Sm-Ion verzerrt oktaedrisch koordiniert. Zusätzlich kristallisiert ein Molekül Dibenzonaphthacen mit aus.
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    Synthesen und Strukturen funktionell substituierter Ferrocene (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 716-722 
    Details
    ISSN: 0044-2313
    Keywords: N,O-Bis(trimethylsilyl)ferrocenylimidate ; E,Z-(Ferrocenyl-trimethylsiloxymethyliden)trimethylsilylphosphane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses and Structures of functional substituted FerrocenesSubstituted ferrocenes have been prepared using carbonic acid chloride of ferrocene. New pathways have been found reacting the acid chloride with sodium hexamethyldisilazane and tris(trimethylsilyl)phosphane, respectively. The compounds FecC(OSiMe3)N(SiMe3) (Fec = C5H5FeC5H4) 1 and FecC(OSiMe3)P(SiMe3) 2 have been obtained and characterized by X-ray single crystal structure analysis. Experiments for the preparation of FecCP 3 are reported.
    Notes: Zur Synthese funktionell substituierter Ferrocene wurde Ferrocencarbonsäurechlorid mit Natriumhexamethyldisilazan und Tris(trimethylsilyl)phosphan umgesetzt und das Imidat FecC(OSiMe3)N(SiMe3) (Fec = C5H5FeC5H4) 1 und das Phosphaalken FecC(OSiMe3)P(SiMe3) 2 erhalten. Versuche zur Darstellung von FecCP 3 werden mitgeteilt. Von den Verbindungen 1 und 2 konnten Einkristall-Röntgenstrukturanalysen angefertigt werden.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200422
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    Über Chalkogenolate. 203. Derivate der Selendithioallophansäure 2. Darstellung und Eigenschaften von Alkylestern (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 730-732 
    Details
    ISSN: 0044-2313
    Keywords: Alkyl esters of selenodithioallophanic acid ; synthesis ; electron absorption spectra ; infrared spectra ; nuclear magnetic resonance spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 203. Derivatives of Selenodithioallophanic Acid. 2. Preparation and Properties of Alkyl EstersSynthesis and properties of selenodithioallophanic acid esters H2N—CSe—NH—CS—SR where R = CH3, C2H5 as well as their characterization by means of electron absorption, infrared, and nuclear magnetic resonance spectra are described.
    Notes: Synthese und Eigenschaften von Alkylestern der Selendithioallophansäure H2N—CSe—NH—CS—SR mit R = CH3, C2H5 sowie deren Charakterisierung durch Elektronenabsorptions-, Infrarot- und kernmagnetische Resonanzspektren werden beschrieben.
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    Dimethylzinndithioquadratat: Die Kristallstruktur des Benzol-Solvats und des Dimethylsulfoxid-Addukts (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 723-729 
    Details
    ISSN: 0044-2313
    Keywords: Dimethyltin dithiosquarate benzene solvate ; Dimethyltin dithiosquarate-dimethylsulfoxide adduct ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimethyltin Dithiosquarate: The Crystal Structure of the Benzene Solvate and of the Dimethylsulfoxide Adduct(CH3)2SnS2C4O2 · 1/3 C6H6 (I) crystallizes in the orthorhombic space group Pnma. a = 14.393(2), b = 21.668(3), c = 10.424(1) Å, Z = 12.(CH3)2SnS2C4O2 · (CH3)2SO (II) is monoclinic, space group P21/n, a = 9.918(5), b = 12.028(6), c = 12.223(6) Å, β = 108.82(3)°, Z = 4.In I there are two independent dimethyltin dithiosquarate molecules. But in both molecules the Sn atoms display weak coordinative bonds to two O atoms of adjacent dithiosquarate groups. The distances amount 2.873 Å (2×), resp. 2.678 and 2.831 Å. The coordination number of tin becomes 6 and the structure gets connected in three dimensions.In II dimethylsulfoxide is bound with the O atom to Sn (2.345 Å) and the result is a distorted trigonal bipyramid. There a more distant O atom (2.944 Å) leads to a connection of the molecules to a ribbon. The changes of the geometrical parameters are described, which result from the progressive approach of the one O atom.
    Notes: (CH3)2SnS2C4O2 · 1/3 C6H6 (I) kristallisiert in der orthorhombischen Raumgruppe Pnma; a = 14,393(2); b = 21,668(3); c = 10,424(1) Å; Z = 12.(CH3)2SnS2C4O2 · (CH3)2SO (II) ist monoklin, Raumgruppe P21/n; a = 9,918(5); b = 12,028(6); c = 12,223(6) Å; β = 108,82(3)°; Z = 4.In I liegen zwei kristallographisch unabhängige Dimethyl-zinndithioquadratat-Moleküle vor. Bei beiden weisen jedoch die Sn-Atome schwache koordinative Bindungen zu zwei O-Atomen benachbarter Dithioquadratat-Gruppen auf. Die Abstände betragen 2,873 Å (2×) bzw. 2,678 und 2,831 Å. Dadurch erhält Zinn die Koordinationszahl 6, und es ergibt sich eine dreidimensional vernetzte Struktur.In II ist Dimethylsulfoxid über das O-Atom an Sn gebunden (2,345 Å), und es liegt eine verzerrte trigonale Bipyramide vor. Ein weiter entferntes O-Atom (2,944 Å) bewirkt hier die Vernetzung der Moleküle zu einem Band. Die Veränderungen der geometrischen Parameter als Folge der fortschreitenden Annäherung des einen O-Atoms werden beschrieben.
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    Chemischer Transport und Sublimationsverhalten von CrBr3  -  Experimente und Modellrechnungen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 73-80 
    Details
    ISSN: 0044-2313
    Keywords: Chromium bromide ; chemical vapor transport ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Chemical Transport and Sublimation of CrBr3  -  Experiments and Model CalculationsThe migration of CrBr3 in the presence of high concentrations of bromine (for example D(Br2) = 0,05 mmol/ml; closed silica ampoules) in the investigated temperature range (T̄ = 625°C to 875°C; T̄ = 50°C) is a result from the endothermic reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(1)} & {{\rm CrBr}_{{\rm 3,s}} + 1/2{\rm Br}_{{\rm 2,g}} = {\rm CrBr}_{4,{\rm g}}}\end{array} $$\end{document} The chemical transport of CrBr3 is superimposed with the sublimation. With low concentrations of D(Br2) and high temperatures T̄ is the sublimation decisive participated. This is a result of the homogenous equilibrium between CrBr3,g and CrBr4,g (2a) \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(2)} & {{\rm CrX}_{{\rm 4,g}} = {\rm CrX}_{{\rm 3,g}} + 1/2\,{\rm X}_{{\rm 2,g}},} & {({\rm a)\,X} = {\rm Br,}} & {{\rm (b)\,X} = {\rm Cl}}\end{array} $$\end{document} The reaction (2a) in comparison with the chemical transport of CrCl3 with Cl2 (Gl. (2b)) is more shifted to CrBr3,g.
    Notes: CrBr3 wandert in einer geschlossenen Ampulle bei hohen Transportmitteldichten (z. B. D(Br2)  -  0,05 mmol/ml) im untersuchten Temperaturbereich (T̄ = 625°C bis 875°C; T̄ = 50°C) von der heißeren (T2) in die weniger heiße Zone (T1) über das endotherme Transportgleichgewicht \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(1)} & {{\rm CrBr}_{{\rm 3,s}} + 1/2{\rm Br}_{{\rm 2,g}} = {\rm CrBr}_{4,{\rm g}}}\end{array} $$\end{document} Der chemische Transport von CrBr3 wird von einer Sublimation überlagert, die bei niedrigeren Transportmitteldichten D(Br2) und höherer Temperatur T̄ maßgeblich beteiligt ist, wie die Lage des homogenen Gasphasengleichgewichts (2a) zwischen CrBr3,g und CrBr4,g zeigt. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(2)} & {{\rm CrX}_{{\rm 4,g}} = {\rm CrX}_{{\rm 3,g}} + 1/2\,{\rm X}_{{\rm 2,g}},} & {({\rm a)\,X} = {\rm Br,}} & {{\rm (b)\,X} = {\rm Cl}}\end{array} $$\end{document} Gleichgewicht (2a) liegt im Vergleich zum chemischen Transport von CrCl3 mit Cl2 (Gl. (2b)) mehr auf der Seite von CrBr3,g.
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    Die Elektronische Struktur von Nb3Br8 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 81-84 
    Details
    ISSN: 0044-2313
    Keywords: Nb3Br8 ; electronic structure ; molecular orbitals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Electronic Structure of Nb3Br8The bonding in Nb3Br8 was investigated with the aid of extended Hückel and molecular orbital calculations to gain some understanding concerning stability and possible chemical altering. Seven electrons occupy metal - metal bonding states of a Nb3Br8 unit. Six of them are responsible for strong σ bonds within the Nb3 cluster. One to two additional electrons may be incorporated to occupy a1 orbitals, which slightly increase the bonding in a Nb3 cluster, rather than between adjacent clusters.
    Notes: Die Bindungsverhältnisse in Nb3Br8 werden mittels Extended-Hückel- und Molekülorbital-Rechnungen untersucht, um hieraus Hinweise auf die Stabilität und mögliche chemische Modifizierbarkeit zu erhalten. Sieben Elektronen sind den Metall - Metall-bindenden Zuständen einer Nb3Br8-Einheit zuzurechnen. Sechs davon sind für starke σ-Bindungen in den Nb3-Clustern verantwortlich. Ein bis zwei zusätzliche Elektronen können in den a1-Orbitalen untergebracht werden, die sich innerhalb eines Nb3-Clusters schwach bindungsverstärkend auswirken, nicht aber zwischen benachbarten Clustern.
    Additional Material: 4 Ill.
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    Synthese und Eigenschaften von molekularen Leitern auf der Basis von dmit-isologen Chelaten Kristall- und Molekülstruktur des Tetramethylammonium-bis-[bis-(1,3-dithiol-2-selon-4,5-diselenolato)nickelat]; [(CH3)4N][Ni(dsise)2]2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 90-100 
    Details
    ISSN: 0044-2313
    Keywords: Dichalcogenolenchelates ; conducting materials ; x-ray ; EPR ; dmit isologues ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses and Properties of Molecular Conductors based on dmit isologous Chelates. Crystal and Molecular Structure of Tetramethylammonium-bis-[bis(1,3-dithiole-2-selone-4,5-diselenolato)nickelate]; [(CH3)4N] [Ni(dsise)2]2Syntheses and properties of dichalcogenolate chelates of the general type [(CH3)4N]n[ML2] (n ≤ 2; M = Ni, Pd, Pt); L = dmit (1,3-dithiole-2-thione-4,5-dithiolate), dmise (1, 3-dithiole-2-selone-4,5-dithiolate), dsit (1, 3-dithiole-2-thione-4,5-diselenolate), dsise (1, 3-dithiole-2-selone-4,5-diselenolate), dsis (1, 3-diselenole-2-selone-4,5-diselenolate) are reported. The effects of the chalcogen atom variation in these chelates are discussed by using UV/VIS, IR, EPR, cyclovoltammetric and conductivity data. The x-ray structure of [(CH3)4N][Ni(dsise)2]2 (space group Pccn, a = 7.427(1), b = 39.144(5), c = 11.836(1) Å) and the conductivity of the crystal (12 S cm-1 at room temperature) are given.
    Notes: Synthese und Eigenschaften von Dichalkogenolat-Chelaten vom Typ [(CH3)4N]n[ML2] mit n ≤ 2; M = Ni, Pd, Pt und L = dmit (1, 3-Dithiol-2-thion-4,5-dithiolat), dmise (1,3-Dithiol-2-selon-4,5-dithiolat), dsit (1,3-Dithiol-2-thion-4,5-diselenolat), dsise (1,3-Dithiol-2-selon-4,5-diselenolat) und dsis (1, 3-Diselenol-2-selon-4, 5-diselenolat) werden beschrieben. Anhand von UV/VIS-, IR-, EPR-, cyclovoltammetrischen und Leitfähigkeitsuntersuchungen werden die Auswirkungen der Chalkogenvariation in den Chelaten diskutiert. Die röntgenkristallographischen Daten von [(CH3)4N] [Ni(dsise)2]2 (Raumgruppe Pccn, a = 7,427(1), b = 39,144(5), c = 11,836(1) Å) und die Kristalleitfähigkeit (12 S cm-1, Raum-temperatur) werden vorgestellt.
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    Na2[Pr4O2]Cl9 und K2[Pr4O2]Cl9, die ersten reduzierten quaternären Praseodymchloride mit anti-SiS2-analogen [Pr4/2O]-Ketten (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 85-89 
    Details
    ISSN: 0044-2313
    Keywords: Praseodymium ; Reduced Chlorides ; Synthesis ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Na2[Pr4O2]Cl9 and K2[Pr4O2]Cl9, the First Reduced Quaternary Praseodymium Chlorides with Anti-SiS2 Analogous [Pr4/2O] ChainsThe compounds A2[Pr4O2]Cl9 (A = Na, K) are the first reduced quaternary praseodymium chlorides with anti-SiS2 analogous [Pr4/2O] chains. Synthesis took place in the temperature range from 900 to 600°C in silica-jacketed niobium containers from Pr metal, PrCl3, PrOCl and NaCl (KCl) as starting materials. The X-ray structure analysis of a single crystal of Na2[Pr4O2]Cl9 (monoclinic, P21/m (No. 11), Z = 2, a = 812.2(2) pm, b = 1 134.1(2) pm, c = 937.6(2) pm, β = 106.51(2)°, R = 0.048, Rw = 0.037) exhibits trans-edge connected chains of [Pr4/2O] tetrahedra running along [001] which are connected by surrounding common chloride ions forming layers parallel to (001). These layers are connected by further chloride ions to a three-dimensional network. The sodium ions surrounded by a heavily distorted octahedron of chloride ions are placed between the layers. The X-ray structure analysis of a single crystal of the otherwise isotypic K2[Pr4O2]Cl9 (monoclinic, P21/m (No. 11), Z = 2, a = 820.6(2) pm, b = 1 133.2(4) pm, c = 949.2(3) pm, β = 103.94(2)°, R = 0.073, Rw = 0.054) shows that potassium is coordinated by nine chloride ions.
    Notes: Erstmals erhalten wurden reduzierte quaternäre Praseodymchloride mit anti-SiS2-analogen [Pr4/2O]-Ketten vom Typ A2[Pr4O2]Cl9 (A = Na, K). Die Synthese erfolgt im Temperaturbereich von 900 bis 600°C in quarzglasummantelten Niobampullen aus Pr-Metall, PrCl3, PrOCl und NaCl bzw. KCl. Die Röntgenstrukturanalyse an einem Einkristall von Na2[Pr4O2]Cl9 (monoklin, P21/m, Z = 2, a = 812,2(2) pm, b = 1 134,1(2)pm, c = 937,6(2)pm, β = 106,51(2)°, R = 0,048, Rw = 0,037) zeigt, daß die entlang [010] verlaufenden, über gemeinsame transständige Pr—Pr-Kanten zu Ketten verknüpften [Pr4/2O]-Tetraeder in der (001)-Ebene über umgebende, gemeinsame Chloratome zu Schichten verknüpft sind, die ihrerseits über Chloratome zu einer dreidimensionalen Struktur verbunden sind. Zwischen den Schichten befindet sich Na+, stark verzerrt oktaedrisch von Cl- umgeben. Die Röntgenstrukturanalyse an einem Einkristall des ansonsten isotypen K2[Pr4O2]Cl9 (monoklin, P21/m (Nr. 11), Z = 2, a = 820,6(2)pm, b = 1 133,2(4)pm, c = 949,2(3)pm, β = 103,94(2)°, R = 0,073, Rw = 0,054) zeigt, daß K+ dort von 9 Cl- umgeben ist.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200114
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  • 98
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    CO2-Transfer durch Metallphenolate: N-Methyl-ε-carolactam/Natriumphenolat als selektives Reagenz für Carboxylierungsreaktionen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 101-106 
    Details
    ISSN: 0044-2313
    Keywords: Sodium phenoxide ; CO2 transfer ; carboxylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CO2 Transfer by Metal Phenoxides: N-Methyl-ε-caprolactam/Sodium Phenoxide as a Selective Reagent for Carboxylation ReactionsCarboxylation reaction of aceton and other substrates with active C—H bonds can be carried out selectively by complexes of sodium phenoxide with N-methyl-ε-caprolactam („NMC“) and CO2. With aceton 3-keto-glutaric acid is formed in 85% yield upon hydrolysis. X-Ray structural analysis of the tetrameric [(NMC)Na(OPh)]4 shows that sodium- and oxygen ions of the phenoxide occupy the positions of a cubus. NMC acts as monodendate ligand, the oxygen atoms of the phenoxide are tridendate bridging ligands. The lithium compound has a similar structure. The complex solved in NMC takes up 0.5 mol CO2 per mol Natrium which at room temperature and normal pressure is transformed to aceton.
    Notes: Carboxylierungsreaktionen von Aceton und anderen Substraten mit aktiven C—H-Bindungen können selektiv mit Komplexen des Natriumphenolats mit N-Methyl-ε-caprolactam („NMC“) und CO2 durchgeführt werden. Mit Aceton entsteht in 85% Ausbeute nach Hydrolyse 3-Ketoglutarsäure. Die Röntgenstrukturanalyse des tetrameren Komplexes [(NMC)Na(OPh)]4 zeigt, daß Natrium- und Phenolatsauerstoffionen die Ecken eines Würfels besetzen.Na1 hat die Koordinationszahl 4. NMC fungiert als einzähliger Ligand, die Sauerstoffatome des Phenolats sind dreizählige Liganden. Die Lithiumverbindung hat eine vergleichbare Struktur. Der Komplex nimmt pro Mol Natriumion in NMC 0,5 Mol CO2 auf, das bei Raumtemperatur und Normaldruck auf Aceton übertragen wird.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200116
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  • 99
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    Synthese und Kristallstruktur von Cu4[PhN3C6H4N3(H)Ph]4(μ2-O)2, einem vierkernigen Kupfer(II)-Komplex mit 1-Phenyltriazenido-2-phenyltriazenobenzol als Ligand (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 107-111 
    Details
    ISSN: 0044-2313
    Keywords: Tetrameric copper(II) complex ; μ2-oxo ligand ; 1-phenyltriazenido-2-phenyltriazeno benzene ligand ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of Cu4[PhN3C6H4N3(H)Ph]4(μ2-O)2, a Tetranuclear Copper(II) Complex with 1-Phenyltriazenido-2-phenyltriazeno-benzene as LigandCu4[PhN3C6H4N3(H)Ph]4(μ-O)2 (1) results from the reaction of an aqueous solution of [Cu(NH3)4]2+ with 1,2-bis(phenyltriazeno)benzene in ether. 1 crystallizes in the orthorhombic space group Pba2 with the lattice parameters a = 1661.5(5), b = 1914.7(7), c = 1269.2(5) pm; Z = 2. In the tetrameric complex with the symmetry C2 the Cu2+ cations form a tetrahedron (Cu—Cu: 298.3(1)-337.1(1) pm). The μ2-oxo ligands occupy the twofold axis and bridge two opposite edges of the Cu4 tetrahedron (Cu—O: 190.0(3) and 192.5(4) pm). The 1-phenyltriazenido-2-phenyltriazeno benzene anions bridge two Cu2+ ions chelating one metal ion and coordinating monodentate the neighbouring one (Cu—N: 191.0(5)-204.1(4) pm).
    Notes: Cu4[PhN3C6H4N3(H)Ph]4(μ-O)2 (1) entsteht bei der Umsetzung einer wäßrigen Lösung von [Cu(NH3)4]2+ mit 1,2-Bis(phenyltriazeno)benzol in Ether. 1 kristallisiert orthorhombisch in der Raumgruppe Pba2 mit den Gitterkonstanten a = 1661,5(5); b = 1914,7(7); c = 1269,2(5) pm; Z = 2. Im tetrameren Komplex mit der Symmetrie C2 bilden die Cu2+-Ionen ein Tetraeder (Cu—Cu: 298,3(1)-337,1(1) pm). Die μ2-Oxoliganden liegen auf der C2-Achse und überbrücken zwei gegenüberliegende Tetraederkanten (Cu—O: 190,0(3) und 192,5(4) pm). Die 1-Phenyltriazenido-2-phenyltriazeno-benzol-Anionen verbrücken benachbarte Cu2+-Ionen, die sie einerseits chelatisierend und andererseits einzähnig koordinieren (Cu—N: 191,0(5)-204,1(4) pm).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200117
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  • 100
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    Crystal and molecular structure of Dicyanotetrasulfane S4(CN)2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 117-120 
    Details
    ISSN: 0044-2313
    Keywords: X-ray crystallography ; sulfur-sulfur bonds ; tetra-sulfides ; dicyanosulfanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kristall- und Molekülstruktur von Dicyanotetrasulfan S4(CN)2S4(CN)2 kristallisiert in der monoklinen Raumgruppe P21/c mit den im Abstract angegebenen Parametern. Die Moleküle besetzen allgemeine Lagen, sind aber ungefähr von C2-Symmetrie. Die Konformation ist all-trans mit den Torsionswinkeln CSSS = 74,6° und 81,7° sowie SSSS = 84,8°. Die mittlere SS-Bindung (201,7 pm) ist viel kürzer als die äußeren (Mittelwert 206,8 pm). Die intermolekularen Wechselwirkungen sind vom van-der-Waals-Typ.
    Notes: S4(CN)2 crystallizes in the monoclinic space group P21/c with a = 885.7 pm, b = 794.2 pm, c = 1032.6 pm, β = 109.0° (at 173 K). The molecules occupy general sites but are of approximate C2 symmetry. The conformation of the molecules is all-trans with torsional angles CSSS = 74.6° and 81.7° and SSSS = 84.8°. The central SS bond (201.7 pm) is much shorter than the terminal SS bonds (av. 206.8 pm). There are no stronger than van-der-Waals type intermolecular interactions.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200119
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