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  • Inorganic Chemistry  (9,028)
  • Aircraft Stability and Control
  • 2015-2019  (68)
  • 1980-1984  (3,515)
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  • 1
    Publication Date: 2019-07-20
    Description: These slides describe a method and technology of modeling flexible aircraft for active control of structural dynamics. Objective: Generate models useful for the design and evaluation of control laws for active structural control and flutter suppression that are able to accurately predict body freedom flutter.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN66921 , Aerospace Control and Guidance Systems Committee (ACGSC) Meeting; Mar 27, 2019 - Mar 29, 2019; Santa Fe, NM; United States
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  • 2
    Publication Date: 2019-07-20
    Description: A multi-objective optimal control technique is modified to accommodate changing cost function weights and is used to control a flexible wing aircraft model. Variation of the weights is used to adjust the relative importance of each objective according to either a prescribed function of time or of the state. Several techniques for obtaining a practical approximation to the optimal control solution are presented, and stability of a specific weight structure with the optimal controller is demonstrated. Functionality of the multi-objective control design with weight variation is demonstrated in simulation of a flexible wing transport aircraft and is shown to improve performance over the fixed weight version both at a constant flight condition and across changing flight conditions.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN64647 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 3
    Publication Date: 2019-07-20
    Description: A new 6-DoF aeroservoelastic (ASE) Common Research Model (CRM) provided by The Boeing Company with aspect ratio 13.5 and 17 control surfaces per wing is utilized to demonstrate combined tracking and optimal multi-objective control. The multi-objective controller is derived on the closed loop tracking controller, and utilizes state and gust estimates provided by an extended state observer. Various methods of model reduction useful for control and estimation are presented. A computationally efficient MATLAB/Simulink simulation is presented which includes actuator dynamics, rate and deflection saturation limits, and gust disturbance inputs. The platform is used to demonstrate excellent 6-DoF tracking control performance coupled with the multi-objective controller, which is shown to effectively reduce structural mode movement, wing root bending moment, and drag. State and gust estimation is also shown to perform well, even when derived and/or implemented with significantly fewer states than the original full-sized model.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN271828 , AIAA Science and Technology Forum and Exposition; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 4
    Publication Date: 2019-07-20
    Description: Slides for an invited presentation (as part of a series) at Santa Clara University, invited by prof. Mohammad Ayoubi. The slides are an overview and summary of past and current research projects in the field of envelope protection, upset prevention and stall recovery guidance, with the aim to avoid loss of control accidents and improve safety in air transportation. The overall aim of this presentation series is to inspire students and to show them possible opportunities that they can pursue for their later careers paths.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN52363 , Santa Clara University Invited Lecture Series; Santa Clara, CA; United States
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  • 5
    Publication Date: 2019-09-13
    Description: An extension of model reference adaptive control is presented that accommodates use of a time-varying reference model. Specifically, the reference model is taken to be a time-varying convex combination of two linear, time-invariant models. The design is intended to act as a way to smoothly transition between two different reference models without resorting to a scheduled switch. It also provides the ability to use an interpolated reference model when the plant is operating between design points. The time variation of the combination must satisfy some requirements to ensure stability but is otherwise user choice. Subject to these requirements, bounded tracking error behavior is demonstrated via Lyapunov stability analysis for the single-input, single-output, output feedback case. Tracking error convergence is asymptotic when time variation ceases. The proposed design is demonstrated in simulation of a numerical model.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN66631 , American Control Conference; Jul 10, 2019 - Jul 12, 2019; Philadelphia, PA; United States
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  • 6
    Publication Date: 2019-10-30
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN74004
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  • 7
    Publication Date: 2019-07-13
    Description: This paper verifies a motion cueing strategy for improved pilot stall recovery training in commercial transport simulators. Eight airline transport pilots flew a high-altitude stall recovery task in the NASA B747 level-D-certified full flight simulator under three different motion configurations: no motion, baseline motion, and enhanced motion. For each motion condition, pilots performed the task with both baseline aircraft dynamics and aircraft dynamics enhanced with lateral-directional characteristics of the airplane at angle of attack approaching stall. Motion configuration significantly affected: 1) pilot opinions on the helpfulness of motion in performing the task, 2) the maximum roll angle in the stall maneuver, 3) the minimum load factor in the recovery, 4) the number of secondary stick shakers in the stall recovery, and 5) the maximum airspeed in the recovery. The two different aircraft dynamics significantly affected: 1) pilot opinions on the noticeability of the banking roll off near the stall and 2) the maximum roll angle in the stall maneuver. These results indicate that the relatively minor enhancements to the motion logic of heritage commercial transport simulators presented here can significantly improve pilot performance in simulated stall recoveries, and potentially improve stall recovery training.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN65276 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 8
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    In:  CASI
    Publication Date: 2019-07-13
    Description: An overview of the flight control work in the Intelligent Systems Division at NASA Ames is presented. The highlight focuses on efforts surrounding performance-adaptive aeroelastic wing shaping for aircraft with flexible wings. Topics covered include aeroservoelastic modeling capabilities, online drag-optimizing control designs, gust and maneuver load alleviation techniques, and related wind tunnel demonstrations.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN67091 , Aerospace Control and Guidance Systems Committee Meeting; Mar 27, 2019 - Mar 29, 2019; Santa Fe, NM; United States
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  • 9
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: JSC-E-DAA-TN69878-2 , AIAA AVIATION Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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  • 10
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: JSC-E-DAA-TN69878-1 , AIAA AVIATION Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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  • 11
    Publication Date: 2019-07-20
    Description: The ability to meet a controlled time of arrival during a continuous descent operation will enable environmentally friendly and fuel efficient descent operations while simultaneously maintaining airport throughput. Previous work showed that guidance strategies based on a frequent recalculation of the optimal trajectory during the descent result in excellent environmental impact mitigation figures while meeting operational constraints in the presence of modelling errors. However, the time lag of recalculating the trajectory using traditional optimisation algorithms could lead to performance degradation and stability issues. This paper proposes an alternative strategy, which allows for fast updates of the optimal trajectory based on parametric sensitivities. Promising results show that the performance of this method is comparable to that of instantaneously recalculating the optimal descent trajectory at each time sample.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-30424 , AIAA/IEEE Digital Avionics Systems Conference (DASC); Sep 23, 2018 - Sep 27, 2018; London, England; United Kingdom
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  • 12
    Publication Date: 2019-07-20
    Description: A deconvolution method is presented for estimating input data from measured output data and a model of the dynamic process involved. The method uses an optimal Wiener filter for separating the measured data into signal and noise components, and a high-accuracy Fourier transform for inverting the model dynamics in the frequency domain. The method is an extension of optimal Fourier smoothing, and uses a technique to enhance the contrast between the signal and noise spectra in designing the Wiener filter. The deconvolution method was applied to simulation and flight test data for the purposes of removing unwanted distortions introduced by signal-conditioning filters and sensor dynamics, and for reconstructing turbulence inputs from measured sensor data. Results indicated hat the method performs well given good signal-to-noise levels and accurate models of the dynamic process.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28783 , AIAA Aviation and Aeronautics Forum and Exposition; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 13
    Publication Date: 2019-07-20
    Description: A method for estimating aeroelastic stability and control derivatives for flexible aircraft is developed and demonstrated using flight test data for the X-56A subscale demonstrator. The method uses the equation-error approach with frequency-domain data, and can be applied post-flight or in real time during flight. The non-dimensional aeroelastic forces and moments and the explanatory variables (including generalized displacement, rate, and acceleration states for the vibration modes) are estimated using a finite element model and onboard sensor measurements in both a least squares and Kalman filtering framework. The data are then transformed into the frequency domain for parameter estimation using equation error. This method can result in a more efficient analysis than with other iterative methods, and can leverage existing statistical tools for model structure determination, data collinearity detection, combining multiple maneuvers or prior information, and others to improve model quality.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28533 , AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 14
    Publication Date: 2019-07-20
    Description: Active flutter suppression has been demonstrated in simulation by many researchers, generally using methods based on linear aerodynamics and often with simplistic geometries. In this paper, active flutter suppression is demonstrated in a simulation using a Navier-Stokes aerodynamics code, FUN3D (Fully Unstructured Navier-Stokes Three-Dimensional), and a realistic transport aircraft configuration. This is accomplished using simple observer-feedback controllers derived from linear aeroelastic models, including reduced order models built via FUN3D data. The development of these reduced order models is described here. It is shown that controllers derived from reduced order models of the nonlinear aerodynamics outperform controllers based on linear aerodynamics.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28523 , AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 15
    Publication Date: 2019-07-13
    Description: In recent studies, it has been observed that loss of control in flight is the most frequent primary cause of accidents. A significant share of accidents in this category can be remedied by upset prevention if possible, and by upset recovery if necessary, in this order of priorities. One of the most important upsets to be recovered from is stall. Recent accidents have shown that a correct stall recovery maneuver remains a big challenge in civil aviation, partly due to a lack of pilot training. A possible strategy to support the flight crew in this demanding context is calculating a recovery guidance signal, and showing this signal in an intuitive way on one of the cockpit displays, for example by means of the flight director. Different methods for calculating the recovery signal, one based on fast model predictive control and another using an energy based approach, have been evaluated in four relevant operational scenarios by experienced commercial as well as test pilots in the Vertical Motion Simulator at NASA Ames Research Center. Evaluation results show that this approach could be able to assist the pilots in executing a correct stall recovery maneuver.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN50867 , SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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  • 16
    Publication Date: 2019-07-13
    Description: This paper describes a recent development of an integrated fully coupled aeroservoelastic flight dynamic model of the NASA Generic Transport Model (GTM). The integrated model couples nonlinear flight dynamics to a nonlinear aeroelastic model of the GTM. The nonlinearity includes the coupling of the rigid-body aircraft states in the partial derivatives of the aeroelastic angle of attack. Aeroservoelastic modeling of the control surfaces which are modeled by the Variable Camber Continuous Trailing Edge Flap is also conducted. The R.T. Jones' method is implemented to approximate unsteady aerodynamics. Simulations of the GTM are conducted with simulated continuous and discrete gust loads..
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN50754 , AIAA SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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  • 17
    Publication Date: 2019-07-13
    Description: Stall characteristics of a wing whose design was based on Prandtls minimum induced drag analysis is presented. Flow field is resolved using RANS CFD (Computational Fluid Dynamics) solver OVERFLOW-2. Both in freestream and in ground effect are analyzed. In addition, effect of low-Mach preconditioner on the stall characteristic is presented. Results show that simulations that lack preconditioner predicts higher stall angle as well as much more benign behavior near the stall angle. Stall analysis in freestream show that flow begins to separate at the inboard region. The flow at the tip remains attached until approximately 19.0 degrees angle of attack.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN48257 , AIAA Applied Aerodynamics Conference; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States|AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 18
    Publication Date: 2019-07-13
    Description: These slides are the companion to the paper on the ACT experiment flown using a G-III autopilot and ADS-B datalink.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN58037 , AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 19
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    In:  CASI
    Publication Date: 2019-07-13
    Description: This presentation discusses the NASA Armstrong PTERA-SAW flight simulation. The uses of this simulation are to study the aerodynamic effects of moving outer wing panels in flight, develop a flight control system, flight safety analysis, mission planning, flight envelope expansion, and post-flight data analysis.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN57916 , AIAA Aviation 2018; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 20
    Publication Date: 2019-08-28
    Description: An extremum-seeking control system for formation flight that uses blended performance parameters in a conglomerate performance function that better approximates drag reduction than performance functions formed from individual measurements. Generally, a variety of different measurements are taken and fed to a control system, the measurements are weighted, and are then subjected to a peak-seeking control algorithm. As measurements are continually taken, the aircraft will be guided to a relative position which optimizes the drag reduction of the formation. Two embodiments are discussed. Two approaches are shown for determining relative weightings: "a priori" by which they are qualitatively determined (by minimizing the error between the conglomerate function and the drag reduction function), and by periodically updating the weightings as the formation evolves.
    Keywords: Aircraft Stability and Control
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  • 21
    Publication Date: 2019-10-19
    Description: Project Link! is a NASA-led effort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a dynamic model and control architecture for a system of fixed-wing vehicles with this capability. The dynamic model consists of the 6 degree-of-freedom fixedwing aircraft equations of motion, a spring-damper-magnet system to represent the linkage force between constituent vehicles, and the NASA-Burnham-Hallock wingtip vortex model to represent the close-proximity aerodynamic interactions between constituents before the linking occurs. The control architecture consists of a guidance algorithm to autonomously drive the constituents towards their linking partners and an inner-loop angular rate controller. A simulation was constructed from the model, and the flight dynamic modes of the linked system were compared to the individual vehicles. The main contributions of this work are twofold. First is the introduction of close-proximity aerodynamic effects to create a realistic simulation framework for this problem. Second is the application of a sophisticated leaderfollower guidance algorithm to achieve in-air wingtip docking. Simulation results for both before and after linking are presented.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28646 , Journal of Guidance, Control, and Dynamics (ISSN 0731-5090) (e-ISSN 1533-3884); 41; 11; 2327-2337
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  • 22
    Publication Date: 2019-07-12
    Description: A summary of output measurement equations for onboard sensors used in flight testing of flexible aircraft is presented. These equations include the effects of structural flexibility and are considerably more complex than the standard equations for rigid-body aircraft. The output equations discussed include accelerations from linear accelerometers, strains, angular rates, angular accelerations, Euler angles, true airspeed, and air flow angles. The output equations are derived in full form and then simplified in some cases. Linearized output equations, suitable for state-space or transfer function models, are also developed. Example flight test data from the X-56A subscale aeroelastic demonstrator is discussed, for reference.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2018-220102 , L-20956 , NF1676L-31027
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  • 23
    Publication Date: 2019-07-13
    Description: From April to May 2017, the National Aeronautics and Space Administration Armstrong Flight Research Center completed a series of flights with a trail C-20A airplane surfing in the wake of a Gulfstream III airplane using a commercially available datalink as the primary communication between the two aircraft. The purpose of this test was to characterize the aerodynamic benefits received by the trail airplane flying in the upwash portion of the wake generated from the lead airplane. Lateral and vertical relative position to the wake were automatically controlled through an experimental programmable autopilot on the C-20A airplane. Long-track, the separation distance between the two aircraft, was maintained by test pilots managing throttle position using customized cockpit displays. These displays provided the pilots with throttle cues for maintaining long-track position and situational awareness of the wake vortex relative to the position of the trail airplane. Flight testing demonstrated the ability of the pilots to use these displays to maintain a safe long-track distance, but found there to be trades between tracking performance and the frequency of throttle motion. The wake awareness display provided the pilots with adequate situational awareness of the wake vortex during the flight experiment. This paper presents a summary of the design, development, and flight evaluation of the pilot displays and long-track control.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN54320 , AIAA Aviation and Aeronautics Forum and Exposition; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 24
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-02-10
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 25
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 26
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Polynitrogens have the potential for ultrahigh-performing explosives or propellants because singly or doubly bonded polynitrogens can decompose to triply bonded dinitrogen (N2) with an extraordinarily large energy release. The large energy content and relatively low activation energy toward decomposition makes the synthesis of a stable polynitrogen allotrope an extraordinary challenge. Many elements exist in different forms (allotropes)—for example, carbon can exist as graphite, diamond, buckyballs, or graphene. However, no stable neutral allotropes are known for nitrogen, and only two stable homonuclear polynitrogen ions had been isolated until now—namely, the N3− anion (1) and the N5+ cation (2). On page 374 of this issue, Zhang et al. (3) report the synthesis and characterization of the first stable salt of the cyclo-N5− anion, only the third stable homonuclear polynitrogen ion ever isolated. Author: Karl O. Christe
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 27
    Publication Date: 2019-06-11
    Description: Three different types of maneuvers were designed to separately quantify the pitch rate and angle-of-attack rate contributions to the nondimensional aerodynamic pitching moment coefficient. These maneuvers combined pilot inputs and automatic multisine excitations, and they were demonstrated with the subscale T-2 and Bat-4 airplanes using the NASA Airborne Subscale Transport Aircraft Research flight-test facility. Stability and control derivatives (in particular, Cmq and Cm) were accurately estimated from the flight-test data. These maneuvers can be performed with many types of aircraft, and the results can be used to improve physical insight into the flight dynamics, facilitate more accurate comparisons with wind-tunnel experiments or numerical investigations, and increase simulation prediction fidelity.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-26357 , Journal of Aircraft (ISSN 0021-8669) (e-ISSN 1533-3868); 54; 6; 2367-2377
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  • 28
    Publication Date: 2019-07-12
    Description: A test in the Langley 12-Foot Low-Speed Tunnel was conducted as a risk mitigation effort to quickly obtain some low-speed stability and control data on a "double-bubble" or D8 transport configuration. The test also tested some configuration design trades. A 5-percent scale model was tested with stabilizer, elevator, rudder and aileron control deflections. This report summarizes the test results.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2017-219797 , L-20897 , NF1676L-29029
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  • 29
    Publication Date: 2019-07-20
    Description: Kalman filter based spacecraft attitude estimation has been used in many space missions and has been widely discussed in literature. While some models in spacecraft attitude estimation include spacecraft dynamics, most do not. To our best knowledge, there is no analysis to determine which model is a better choice. In this paper, we discuss the reasons why spacecraft dynamics should be considered in the Kalman filter based spacecraft attitude estimation problem. We also propose a reduced quaternion spacecraft dynamics model which admits additive noise. Geometry of the reduced quaternion model and the additive noise are discussed. This formulation makes computation easier than the one with full quaternion. Simulations are conducted to justify our claims.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-24892 , Advances in Aircraft and Spacecraft Science (ISSN 2287-528X) (e-ISSN 2287-5271); 4; 3; 335-351
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  • 30
    Publication Date: 2019-07-20
    Description: In this project, work has been done in the field of conceptual design of experimental tiltrotors. The main tools that have been used are NDARC (NASA Design and Analysis of Rotorcraft) and SIMPLI-FLYD. NDARC is a conceptual design tool for rotorcraft, and it is used to find trim points under various flight conditions. SIMPLI-FLYD is an integrated collection of software tools that enables a flight dynamics and control assessment of the rotorcraft vehicle design generated from NDARC. Two different tiltrotors have been investigated. Initially, work was done with the Bell XV- 15 tiltrotor. NDARCs ability to correctly model the tiltwing transition between airplane mode and hover mode was looked into. In addition, data from old flight tests were compared to the NDARC output, to see how accurately performance could be predicted. After the XV-15 analysis, an NDRARC model of a novel tiltwing concept from Elytron Aircraft was written and analyzed together with SIMPLI-FLYD. Elytron 2S is an experimental tiltwing aircraft, consisting of a joined-wing design with a small central wing for the proprotor. An alternative approach to hover control is used, where the typical rotor hub and swash plate are substituted for linear actuators controlling pitch, yaw and roll. The objective with the analysis of Elytron is to obtain a more complete understanding of the maneuverability and possible performance of this alternative aircraft configuration.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN39203 , NASA/CR-2017-219456
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  • 31
    Publication Date: 2019-07-13
    Description: This paper presents a new adaptive control approach that involves a performance optimization objective. The control synthesis involves the design of a performance optimizing adaptive controller from a subset of control inputs. The resulting effect of the performance optimizing adaptive controller is to modify the initial reference model into a time-varying reference model which satisfies the performance optimization requirement obtained from an optimal control problem. The time-varying reference model modification is accomplished by the real-time solutions of the time-varying Riccati and Sylvester equations coupled with the least-squares parameter estimation of the sensitivities of the performance metric. The effectiveness of the proposed method is demonstrated by an application of maneuver load alleviation control for a flexible aircraft.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN42886 , Eighteenth Yale Workshop on Adaptive and Learning Systems; Jun 21, 2017 - Jun 23, 2017; New Haven, CT; United States
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  • 32
    Publication Date: 2019-07-13
    Description: The paper presents an on-board estimation, navigation and control architecture for multi-rotor drones flying in urban environment. It consists of adaptive algorithms to estimate vehicle's aerodynamic drag coefficients with respect to still air and the urban wind components along the flight trajectory, with guaranteed fast and reliable convergence to the true values; navigation algorithms to generate feasible trajectories between given way-points that take into account the estimated wind; and of control algorithms to track the generated trajectories as long as the vehicle retains sufficient number of functioning rotors capable of compensating for the estimated wind. All components of this on-board system are computationally effective and are intended for a real time implementation. The algorithms were tested in simulations.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN38102 , AIAA SciTech Forum; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 33
    Publication Date: 2019-07-13
    Description: While many widely accepted methods and techniques exist for validation and verification of traditional controllers, at this time no solutions have been accepted for Fuzzy Logic Controllers (FLCs). Due to the highly nonlinear nature of such systems, and the fact that developing a valid FLC does not require a mathematical model of the system, it is quite difficult to use conventional techniques to prove controller stability. Since safety-critical systems must be tested and verified to work as expected for all possible circumstances, the fact that FLC controllers cannot be tested to achieve such requirements poses limitations on the applications for such technology. Therefore, alternative methods for verification and validation of FLCs needs to be explored. In this study, a novel approach using formal verification methods to ensure the stability of a FLC is proposed. Main research challenges include specification of requirements for a complex system, conversion of a traditional FLC to a piecewise polynomial representation, and using a formal verification tool in a nonlinear solution space. Using the proposed architecture, the Fuzzy Logic Controller was found to always generate negative feedback, but inconclusive for Lyapunov stability.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN38074 , SciTech 2017; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 34
    Publication Date: 2019-07-13
    Description: Unlike basic Model Reference Adaptive Control (MRAC)l, Optimal Control Modification (OCM) has been shown to be a promising MRAC modification with robustness and analytical properties not present in other adaptive control methods. This paper presents an analysis of the OCM method, and how the asymptotic property of OCM is useful for analyzing and tuning the controller. We begin with a Lyapunov stability proof of an OCM controller having two adaptive gain terms, then the less conservative and easily analyzed OCM asymptotic property is presented. Two numerical examples are used to show how this property can accurately predict steady state stability and quantitative robustness in the presence of time delay, and relative to linear plant perturbations, and nominal Loop Transfer Recovery (LTR) tuning. The asymptotic property of the OCM controller is then used as an aid in tuning the controller applied to a large scale aeroservoelastic longitudinal aircraft model for flutter suppression. Control with OCM adaptive augmentation is shown to improve performance over that of the nominal non-adaptive controller when significant disparities exist between the controller/observer model and the true plant model.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN50278 , AIAA SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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  • 35
    Publication Date: 2019-07-13
    Description: This presentation is given at a NASA DLR (German Aerospace Center) meeting at NASA ARC on March 14, 2017. The presentation provides an overview of the Advanced Control and Evolvable Systems (ACES) group at NASA ARC and the research areas in UAS autonomy, stall recovery guidance, and flexible aircraft flight control.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN39958 , NASA/DLR Collaboration Meeting; Mar 14, 2017; Moffett Field, CA; United States
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  • 36
    Publication Date: 2019-07-13
    Description: This paper discusses the implementation and simulated performance of the FNPEG (Fully Numerical Predictor-corrector Entry Guidance) algorithm into GNC FSW (Guidance, Navigation, and Control Flight Software) for use in an autonomous re-entry vehicle. A few modifications to FNPEG are discussed that result in computational savings -- a change to the state propagator, and a modification to cross-range lateral logic. Finally, some Monte Carlo results are presented using a representative vehicle in both a high-fidelity 6-DOF (degree-of-freedom) sim as well as in a 3-DOF sim for independent validation.
    Keywords: Aircraft Stability and Control
    Type: JSC-CN-38080 , AIAA SciTech Forum 2017; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 37
    Publication Date: 2019-07-13
    Description: Link! is a multi-center NASA e ort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a potential field guidance algorithm for a group of multi-rotor vehicles to link to each other during flight. The linking is done in pairs. Each vehicle first selects a mate. Then the potential field is constructed with three rules: move towards the mate, avoid collisions with non-mates, and stay close to the rest of the group. Once a pair links, they are then considered to be a single vehicle. After each pair is linked, the process repeats until there is only one vehicle left. The paper contains simulation results for a system of 16 vehicles.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-27073 , AIAA Aviation and Aeronautics Forum and Exposition (AIAA Aviation 2017); Jun 05, 2017 - Jun 09, 2017; Denver, CO; United States
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  • 38
    Publication Date: 2019-07-13
    Description: The NASA Unmanned Aircraft System (UAS) Traffic Management (UTM) project is conducting research to enable civilian low-altitude airspace and UAS operations. A goal of this project is to develop probabilistic methods to quantify risk during failures and off nominal flight conditions. An important part of this effort is the reliable prediction of feasible trajectories during off-nominal events such as control failure, atmospheric upsets, or navigation anomalies that can cause large deviations from the intended flight path or extreme vehicle upsets beyond the normal flight envelope. Few examples of high-fidelity modeling and prediction of off-nominal behavior for small UAS (sUAS) vehicles exist, and modeling requirements for accurately predicting flight dynamics for out-of-envelope or failure conditions are essentially undefined. In addition, the broad range of sUAS aircraft configurations already being fielded presents a significant modeling challenge, as these vehicles are often very different from one another and are likely to possess dramatically different flight dynamics and resultant trajectories and may require different modeling approaches to capture off-nominal behavior. NASA has undertaken an extensive research effort to define sUAS flight dynamics modeling requirements and develop preliminary high fidelity six degree-of-freedom (6-DOF) simulations capable of more closely predicting off-nominal flight dynamics and trajectories. This research has included a literature review of existing sUAS modeling and simulation work as well as development of experimental testing methods to measure and model key components of propulsion, airframe and control characteristics. The ultimate objective of these efforts is to develop tools to support UTM risk analyses and for the real-time prediction of off-nominal trajectories for use in the UTM Risk Assessment Framework (URAF). This paper focuses on modeling and simulation efforts for a generic quad-rotor configuration typical of many commercial vehicles in use today. An overview of relevant off-nominal multi-rotor behaviors will be presented to define modeling goals and to identify the prediction capability lacking in simplified models of multi-rotor performance. A description of recent NASA wind tunnel testing of multi-rotor propulsion and airframe components will be presented illustrating important experimental and data acquisition methods, and a description of preliminary propulsion and airframe models will be presented. Lastly, examples of predicted off-nominal flight dynamics and trajectories from the simulation will be presented.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-25779 , 2017 AIAA Aviation and Aeronautics Forum; Jun 05, 2017 - Jun 09, 2017; Denver, CO; United States
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  • 39
    Publication Date: 2019-07-13
    Description: Aircraft dynamics characteristics can only be identified from flight data when the aircraft dynamics are excited sufficiently. A preliminary study was conducted into what types and levels of manual piloted control excitation would be required for accurate Real-Time Parameter IDentification (RTPID) results by commercial airline pilots. This includes assessing the practicality for the pilot to provide this excitation when cued, and to further understand if pilot inputs during various phases of flight provide sufficient excitation naturally. An operationally representative task was evaluated by 5 commercial airline pilots using the NASA Ice Contamination Effects Flight Training Device (ICEFTD). Results showed that it is practical to use manual pilot inputs only as a means of achieving good RTPID in all phases of flight and in flight turbulence conditions. All pilots were effective in satisfying excitation requirements when cued. Much of the time, cueing was not even necessary, as just performing the required task provided enough excitation for accurate RTPID estimation. Pilot opinion surveys reported that the additional control inputs required when prompted by the excitation cueing were easy to make, quickly mastered, and required minimal training.
    Keywords: Aircraft Stability and Control
    Type: NASA/CR-2017-219600
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  • 40
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: M17-5798 , NESC GNC Technical Discipline Team Face-to-Face Meeting; Jan 23, 2017 - Jan 27, 2017; Mountain View, CA; United States
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  • 41
    Publication Date: 2019-07-13
    Description: Three different types of maneuvers were designed to separately quantify pitch rate and angle of attack rate contributions to the nondimensional aerodynamic pitching moment coefficient. These maneuvers combined pilot inputs and automatic multisine excitations, and were own with the subscale T-2 and Bat-4 airplanes using the NASA AirSTAR flight test facility. Stability and control derivatives, in particular C(sub mq) and C(sub m alpha(.)) were accurately estimated from the flight test data. These maneuvers can be performed with many types of aircraft, and the results can be used to increase simulation prediction fidelity and facilitate more accurate comparisons with wind tunnel experiments or numerical investigations.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-24686 , 2017 AIAA SciTech; Jan 09, 2017 - Jan 13, 2017; Dallas, TX; United States
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  • 42
    Publication Date: 2019-07-13
    Description: While many widely accepted methods and techniques exist for validation and verification of traditional controllers, at this time no solutions have been accepted for Fuzzy Logic Controllers (FLCs). Due to the highly nonlinear nature of such systems, and the fact that developing a valid FLC does not require a mathematical model of the system, it is quite difficult to use conventional techniques to prove controller stability. Since safety-critical systems must be tested and verified to work as expected for all possible circumstances, the fact that FLC controllers cannot be tested to achieve such requirements poses limitations on the applications for such technology. Therefore, alternative methods for verification and validation of FLCs needs to be explored. In this study, a novel approach using formal verification methods to ensure the stability of a FLC is proposed. Main research challenges include specification of requirements for a complex system, conversion of a traditional FLC to a piecewise polynomial representation, and using a formal verification tool in a nonlinear solution space. Using the proposed architecture, the Fuzzy Logic Controller was found to always generate negative feedback, but inconclusive for Lyapunov stability.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN32797 , SciTech 2017; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 43
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-08-26
    Description: An aircraft control structure for drag management includes a nozzle structure configured to exhaust a swirling fluid stream. A plurality of swirl vanes are positioned within the nozzle structure, and an actuation subsystem is configured to cause the plurality of swirl vanes to move from a deployed state to a non-deployed state. In the non-deployed state, the plurality of swirl vanes are substantially flush with the inner surface of the nozzle structure. In the deployed state, the plurality of swirl vanes produce the swirling fluid stream.
    Keywords: Aircraft Stability and Control
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  • 44
    Publication Date: 2019-07-13
    Description: As aircraft wings become much more flexible due to the use of light-weight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence increased fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of light-weight material could be offset by less optimal aerodynamic performance at off-design flight conditions. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multi-disciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the optimal aerodynamic performance from being realized. These operational constraints include reduced flutter margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the optimal aerodynamic performance present themselves as a multi-objective flight control problem. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control has already been developed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag minimization demonstrates the effectiveness of the proposed solution. In-flight structural loads are also an important consideration. As wing flexibility increases, maneuver load and gust load responses can be significant and therefore can pose safety and flight control concerns. In this paper, we will extend the multi-objective flight control framework to include load alleviation control. The study will focus initially on maneuver load minimization control, and then subsequently will address gust load alleviation control in future work.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN38210 , AIAA SciTech Forum; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 45
    Publication Date: 2019-07-13
    Description: Aeroelastic stability and control derivatives for the X-56A Multi-Utility Technology Testbed (MUTT), in the stiff-wing configuration, were estimated from flight test data using the output-error method. Practical aspects of the analysis are discussed. The orthogonal phase-optimized multisine inputs provided excellent data information for aeroelastic modeling. Consistent parameter estimates were determined using output error in both the frequency and time domains. The frequency domain analysis converged faster and was less sensitive to starting values for the model parameters, which was useful for determining the aeroelastic model structure and obtaining starting values for the time domain analysis. Including a modal description of the structure from a finite element model reduced the complexity of the estimation problem and improved the modeling results. Effects of reducing the model order on the short period stability and control derivatives were investigated.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-24692 , AIAA SciTech 2017; Jan 09, 2017 - Jan 13, 2017; Dallas, TX; United States
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  • 46
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    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-09-09
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 47
    facet.materialart.
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-11-11
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 48
    Publication Date: 2019-07-13
    Description: A method for estimating dynamic model parameters from flight data with unknown time skews is described and demonstrated. The method combines data reconstruction, nonlinear optimization, and equation-error parameter estimation in the frequency domain to accurately estimate both dynamic model parameters and the relative time skews in the data. Data from a nonlinear F-16 aircraft simulation with realistic noise, instrumentation errors, and arbitrary time skews were used to demonstrate the approach. The approach was further evaluated using flight data from a subscale jet transport aircraft, where the measured data were known to have relative time skews. Comparison of modeling results obtained from time-skewed and time-synchronized data showed that the method accurately estimates both dynamic model parameters and relative time skew parameters from flight data with unknown time skews.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-21730 , 2016 AIAA SciTech Forum and Exposition; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 49
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-07-13
    Description: NASA is in the process of qualifying the mid-size Super Pressure Balloon (SPB) to provide constant density altitude flight for science investigations at polar and mid-latitudes. The status of the development of the 18.8 million cubic foot SPB capable of carrying one-tonne of science to 110,000 feet, will be given. In addition, the operating considerations such as launch sites, flight safety considerations, and recovery will be discussed.
    Keywords: Aircraft Stability and Control
    Type: GSFC-E-DAA-TN32079 , 2016 Scientific Ballooning Technologies Workshop; May 09, 2016 - May 11, 2016; Minneapolis, MN; United States
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  • 50
    Publication Date: 2019-07-13
    Description: The NASA Airborne Subscale Transport Aircraft Research Unmanned Aerial System project's capabilities were expanded by updating the system design and concept of operations. The new remotely piloted airplane system design was flight tested to assess integrity and operational readiness of the design to perform flight research. The purpose of the system design is to improve aviation safety by providing a capability to validate, in high-risk conditions, technologies to prevent airplane loss of control. Two principal design requirements were to provide a high degree of reliability and that the new design provide a significant increase in test volume (relative to operations using the previous design). The motivation for increased test volume is to improve test efficiency and allow new test capabilities that were not possible with the previous design and concept of operations. Three successful test flights were conducted from runway 4-22 at NASA Goddard Space Flight Center's Wallops Flight Facility.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-23006 , 2016 AIAA SciTech Conference; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 51
    Publication Date: 2019-07-13
    Description: Distributed engine control architecture presents a significant increase in complexity over traditional implementations when viewed from the perspective of system simulation and hardware design and test. Even if the overall function of the control scheme remains the same, the hardware implementation can have a significant effect on the overall system performance due to differences in the creation and flow of data between control elements. A Hardware-in-the-Loop (HIL) simulation system is under development at NASA Glenn Research Center that enables the exploration of these hardware dependent issues. The system is based on, but not limited to, the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). This paper describes the step-by-step conversion from the self-contained baseline model to the hardware in the loop model, and the validation of each step. As the control model hardware fidelity was improved during HIL system development, benchmarking simulations were performed to verify that engine system performance characteristics remained the same. The results demonstrate the goal of the effort; the new HIL configurations have similar functionality and performance compared to the baseline C-MAPSS40k system.
    Keywords: Aircraft Stability and Control
    Type: GRC-E-DAA-TN28906 , AIAA SciTech 2016; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 52
    Publication Date: 2019-07-13
    Description: This paper considers an approach for modelling transport aircraft trajectories that can facilitate their rapid evaluation and modification, either en route or in terminal control areas, with the goal of efficiently making use of airspace and runways by a large population of vehicles without pairwise violation of separation criteria.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-24516 , AIAA Aviation Technology, Integration, and Operations Conference; Jun 13, 2016 - Jun 17, 2016; Washington, DC; United States
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  • 53
    Publication Date: 2019-07-13
    Description: A real-time method was demonstrated for determining accurate uncertainty levels of stability and control derivatives estimated using recursive least squares and time-domain data. The method uses a recursive formulation of the residual autocorrelation to account for colored residuals, which are routinely encountered in aircraft parameter estimation and change the predicted uncertainties. Simulation data and flight test data for a subscale jet transport aircraft were used to demonstrate the approach. Results showed that the corrected uncertainties matched the observed scatter in the parameter estimates, and did so more accurately than conventional uncertainty estimates that assume white residuals. Only small differences were observed between batch estimates and recursive estimates at the end of the maneuver. It was also demonstrated that the autocorrelation could be reduced to a small number of lags to minimize computation and memory storage requirements without significantly degrading the accuracy of predicted uncertainty levels.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-21676 , AIAA 2016 SciTech Forum and Exposition; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 54
    Publication Date: 2019-07-13
    Description: Flight testing and modeling techniques were developed to accurately identify global nonlinear aerodynamic models for aircraft in real time. The techniques were developed and demonstrated during flight testing of a remotely-piloted subscale propeller-driven fixed-wing aircraft using flight test maneuvers designed to simulate a Learn-To-Fly scenario. Prediction testing was used to evaluate the quality of the global models identified in real time. The real-time global nonlinear aerodynamic modeling algorithm will be integrated and further tested with learning adaptive control and guidance for NASA Learn-To-Fly concept flight demonstrations.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-21688 , 2016 AIAA SciTech Conference; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 55
    Publication Date: 2019-07-13
    Description: First steps have been taken to qualify a family of parafoil systems capable of increasing the survivability and reusability of high-altitude balloon payloads. The research is motivated by the common risk facing balloon payloads where expensive flight hardware can often land in inaccessible areas that make them difficult or impossible to recover. The Autonomously Navigated Experimental Lander (ANGEL) flight test introduced a commercial Guided Parachute Aerial Delivery System (GPADS) to a previously untested environment at 108,000ft MSL to determine its high-altitude survivability and capabilities. Following release, ANGEL descended under a drogue until approximately 25,000ft, at which point the drogue was jettisoned and the main parachute was deployed, commencing navigation. Multiple data acquisition platforms were used to characterize the return-to-point technology performance and help determine its suitability for returning future scientific payloads ranging from 180 to 10,000lbs to safer and more convenient landing locations. This report describes the test vehicle design, and summarizes the captured sensor data. Various post-flight analyses are used to quantify the system's performance, gondola load data, and serve as a reference point for subsequent missions.
    Keywords: Aircraft Stability and Control
    Type: GRC-E-DAA-TN28393 , AIAA SciTech 2016; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 56
    Publication Date: 2019-07-13
    Description: The paper presents an algorithm for control and safe landing of impaired multi-rotor drones when one or more motors fail simultaneously or in any sequence. It includes three main components: an identification block, a reconfigurable control block, and a decisions making block. The identification block monitors each motor load characteristics and the current drawn, based on which the failures are detected. The control block generates the required total thrust and three axis torques for the altitude, horizontal position and/or orientation control of the drone based on the time scale separation and nonlinear dynamic inversion. The horizontal displacement is controlled by modulating the roll and pitch angles. The decision making algorithm maps the total thrust and three torques into the individual motor thrusts based on the information provided by the identification block. The drone continues the mission execution as long as the number of functioning motors provide controllability of it. Otherwise, the controller is switched to the safe mode, which gives up the yaw control, commands a safe landing spot and descent rate while maintaining the horizontal attitude.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN24294 , AIAA Science and Technology Forum and Exposition (SciTech 2016); Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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  • 57
    Publication Date: 2019-07-13
    Description: The study described in this paper had two objectives. The first objective was to investigate if a different weighting of heave motion components decomposed at the center of gravity, allowing for a higher fidelity of individual components, would result in pilot manual pitch control behavior and performance closer to that observed with full aircraft motion. The second objective was to investigate if decomposing the heave components at the aircraft's instantaneous center of rotation rather than at the center of gravity could result in additional improvements in heave motion fidelity. Twenty-one general aviation pilots performed a pitch attitude control task in an experiment conducted on the Vertical Motion Simulator at NASA Ames under different hexapod motion conditions. The large motion capability of the Vertical Motion Simulator also allowed for a full aircraft motion condition, which served as a baseline. The controlled dynamics were of a transport category aircraft trimmed close to the stall point. When the ratio of center of gravity pitch heave to center of gravity heave increased in the hexapod motion conditions, pilot manual control behavior and performance became increasingly more similar to what is observed with full aircraft motion. Pilot visual and motion gains significantly increased, while the visual lead time constant decreased. The pilot visual and motion time delays remained approximately constant and decreased, respectively. The neuromuscular damping and frequency both decreased, with their values more similar to what is observed with real aircraft motion when there was an equal weighting of the heave of the center of gravity and heave due to rotations about the center of gravity. In terms of open- loop performance, the disturbance and target crossover frequency increased and decreased, respectively, and their corresponding phase margins remained constant and increased, respectively. The decomposition point of the heave components only had limited effects on pilot manual control behavior and performance.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN32614 , AIAA Aviation 2016 Conference; Jun 13, 2016 - Jun 17, 2016; Washington, DC; United States
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  • 58
    Publication Date: 2019-07-12
    Description: Calculated numerical values for some aerodynamic terms and stability Derivatives for several different wings in unseparated inviscid incompressible flow were made using a discrete vortex method involving a limited number of horseshoe vortices. Both longitudinal and lateral-directional derivatives were calculated for steady conditions as well as for sinusoidal oscillatory motions. Variables included the number of vortices used and the rotation axis/moment center chordwise location. Frequencies considered were limited to the range of interest to vehicle dynamic stability (kb 〈.24 ). Comparisons of some calculated numerical results with experimental wind-tunnel measurements were in reasonable agreement in the low angle-of-attack range considering the differences existing between the mathematical representation and experimental wind-tunnel models tested. Of particular interest was the presence of induced drag for the oscillatory condition.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2016-219349 , L-20759 , NF1676L-25593
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  • 59
    Publication Date: 2019-07-13
    Description: A new formulation of the filter-error method for estimating aerodynamic parameters in nonlinear aircraft dynamic models during turbulence was developed and demonstrated. The approach uses an estimate of the measurement noise covariance to identify the model parameters, their uncertainties, and the process noise covariance, in a relaxation method analogous to the output-error method. Prior information on the model parameters and uncertainties can be supplied, and a post-estimation correction to the uncertainty was included to account for colored residuals not considered in the theory. No tuning parameters, needing adjustment by the analyst, are used in the estimation. The method was demonstrated in simulation using the NASA Generic Transport Model, then applied to the subscale T-2 jet-engine transport aircraft flight. Modeling results in different levels of turbulence were compared with results from time-domain output error and frequency- domain equation error methods to demonstrate the effectiveness of the approach.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-20186 , AIAA Atmospheric Flight Mechanics Conference; Jun 22, 2015 - Jun 26, 2015; Dallas,TX; United States
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  • 60
    Publication Date: 2019-07-13
    Description: The implementation and evaluation of an efficient method for estimating safe aircraft maneuvering envelopes are discussed. A Bayesian approach is used to produce a deterministic algorithm for estimating aerodynamic system parameters from existing noisy sensor measurements, which are then used to estimate the trim envelope through efficient high- fidelity model-based computations of attainable equilibrium sets. The safe maneuverability limitations are extended beyond the trim envelope through a robust reachability analysis derived from an optimal control formulation. The trim and maneuvering envelope limits are then conveyed to pilots through three axes on the primary flight display. To evaluate the new display features, commercial airline crews flew multiple challenging approach and landing scenarios in the full motion Advanced Concepts Flight Simulator at NASA Ames Research Center, as part of a larger research initiative to investigate the impact on the energy state awareness of the crew. Results show that the additional display features have the potential to significantly improve situational awareness of the flight crew.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN19341 , AIAA Infotech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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  • 61
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN25157 , South Korean Delegration; Jul 16, 2015; Edwards AFB California; United States
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  • 62
    Publication Date: 2019-07-12
    Description: This report introduces a modeling and simulation tool for aeroservoelastic analysis of rectangular wings with trailing-edge control surfaces. The inputs to the code are planform design parameters such as wing span, aspect ratio, and number of control surfaces. Using this information, the generalized forces are computed using the doublet-lattice method. Using Roger's approximation, a rational function approximation is computed. The output, computed in a few seconds, is a state space aeroservoelastic model which can be used for analysis and control design. The tool is fully parameterized with default information so there is little required interaction with the model developer. All parameters can be easily modified if desired. The focus of this report is on tool presentation, verification, and validation. These processes are carried out in stages throughout the report. The rational function approximation is verified against computed generalized forces for a plate model. A model composed of finite element plates is compared to a modal analysis from commercial software and an independently conducted experimental ground vibration test analysis. Aeroservoelastic analysis is the ultimate goal of this tool, therefore, the flutter speed and frequency for a clamped plate are computed using damping-versus-velocity and frequency-versus-velocity analysis. The computational results are compared to a previously published computational analysis and wind-tunnel results for the same structure. A case study of a generic wing model with a single control surface is presented. Verification of the state space model is presented in comparison to damping-versus-velocity and frequency-versus-velocity analysis, including the analysis of the model in response to a 1-cos gust.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2015-218875 , DFRC-E-DAA-TN25358
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  • 63
    Publication Date: 2019-08-13
    Description: The X-56A Multi-Utility Technology Testbed is an experimental aircraft designed to study active control of flexible structures. The vehicle is easily reconfigured to allow for testing of different configurations. The vehicle is being used to study new sensor, actuator, modeling and controls technologies. These new technologies will allow for lighter vehicles and new configurations that exceed the efficiency currently achievable. A description of the vehicle and the current research efforts that it enables are presented.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN27228 , 2015 IFAR Young Researcher Conference; Oct 04, 2015 - Oct 10, 2015; Moffett Field, CA; United States
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  • 64
    Publication Date: 2019-08-28
    Description: A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.
    Keywords: Aircraft Stability and Control
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  • 65
    Publication Date: 2019-07-13
    Description: A 2015 NASA Aeronautics Mission "Seedling" Proposal is described for a Severe-Environment UAV (SE-UAV) that can perform in-situ measurements in hazardous atmospheric conditions like lightning, volcanic ash and radiation. Specifically, this paper describes the design of a proof-of-concept vehicle and measurement system that can survive lightning attachment during flight operations into thunderstorms. Elements from three NASA centers draw together for the SE-UAV concept. 1) The NASA KSC Genesis UAV was developed in collaboration with the DARPA Nimbus program to measure electric field and X-rays present within thunderstorms. 2) A novel NASA LaRC fiber-optic sensor uses Faraday-effect polarization rotation to measure total lightning electric current on an air vehicle fuselage. 3) NASA AFRC's state-of-the-art Fiber Optics and Systems Integration Laboratory is envisioned to transition the Faraday system to a compact, light-weight, all-fiber design. The SE-UAV will provide in-flight lightning electric-current return stroke and recoil leader data, and serve as a platform for development of emerging sensors and new missions into hazardous environments. NASA's Aeronautics and Science Missions are interested in a capability to perform in-situ volcanic plume measurements and long-endurance UAV operations in various weather conditions. (Figure 1 shows an artist concept of a SE-UAV flying near a volcano.) This paper concludes with an overview of the NASA Aeronautics Strategic Vision, Programs, and how a SE-UAV is envisioned to impact them. The SE-UAV concept leverages high-value legacy research products into a new capability for NASA to fly a pathfinder UAV into hazardous conditions, and is presented in the SPIE DSS venue to explore teaming, collaboration and advocacy opportunities outside NASA.
    Keywords: Aircraft Stability and Control
    Type: SPIE Paper 9468-28 , NF1676L-21134 , SPIE DSS 2015 - Defense and Security Meeting; Apr 20, 2015 - Apr 24, 2015; Baltimore, MD; United States
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  • 66
    Publication Date: 2019-07-13
    Description: This paper describes a transfer-of-training study performed in the NASA Ames Vertica lMotion Simulator. The purpose of the study was to investigate the effect of false tilt cues on training and transfer of training of manual roll control skills. Of specific interest were the skills needed to control unstable roll dynamics of a mid-size transport aircraft close to the stall point. Nineteen general aviation pilots trained on a roll control task with one of three motion conditions: no motion, roll motion only, or reduced coordinated roll motion. All pilots transferred to full coordinated roll motion in the transfer session. A novel multimodal pilot model identification technique was successfully applied to characterize how pilots' use of visual and motion cues changed over the course of training and after transfer. Pilots who trained with uncoordinated roll motion had significantly higher performance during training and after transfer, even though they experienced the false tilt cues. Furthermore, pilot control behavior significantly changed during the two sessions, as indicated by increasing visual and motion gains, and decreasing lead time constants. Pilots training without motion showed higher learning rates after transfer to the full coordinated roll motion case.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2015-0655 , ARC-E-DAA-TN20112 , AIAA SciTech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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  • 67
    Publication Date: 2019-07-13
    Description: Safety of unmanned aerial systems (UAS) is paramount, but the large number of dynamically changing controller parameters makes it hard to determine if the system is currently stable, and the time before loss of control if not. We propose a hierarchical statistical model using Treed Gaussian Processes to predict (i) whether a flight will be stable (success) or become unstable (failure), (ii) the time-to-failure if unstable, and (iii) time series outputs for flight variables. We first classify the current flight input into success or failure types, and then use separate models for each class to predict the time-to-failure and time series outputs. As different inputs may cause failures at different times, we have to model variable length output curves. We use a basis representation for curves and learn the mappings from input to basis coefficients. We demonstrate the effectiveness of our prediction methods on a NASA neuro-adaptive flight control system.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN23968 , Society for Industrial and Applied Mathematics (SIAM) Conference on Control and Its Applications; Jul 08, 2015 - Jul 10, 2015; Paris; France
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  • 68
    Publication Date: 2019-07-12
    Description: This report documents a case study on the application of Reliability Engineering techniques to achieve an optimal balance between performance and robustness by tuning the functional parameters of a complex non-linear control system. For complex systems with intricate and non-linear patterns of interaction between system components, analytical derivation of a mathematical model of system performance and robustness in terms of functional parameters may not be feasible or cost-effective. The demonstrated approach is simple, structured, effective, repeatable, and cost and time efficient. This general approach is suitable for a wide range of systems.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2015-218795 , L-20574 , NF1676L-21781
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  • 69
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 508 (1984), S. 187-190 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Komplexe von Halogeniden der IV. Gruppe mit einzähnigen Schiffschen BasenVerschiedene Komplexe, die bei der Reaktion von N-(phenyl)benzalaldimin und seinen Derivaten mit einer Methylgruppe in verschiedenen Positionen des Anilinringes mit Halogeniden der IV. Gruppe, MX4, (M = Si bzw. Sn und X = Cl bzw. Br) entstehen, wurden hergestellt und mittels UV-, IR- und Raman-Spektren charakterisiert.
    Notes: Coordination compounds resulting from the interaction of N-(phenyl)benzalaldimine and its derivatives containing a methyl group in different positions of the aniline ring and group(IV) halides, MX4 (where M = Si or Sn and X = Cl or Br), have been prepared and characterized by elemental analyses and electronic, infrared and Raman spectra.
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  • 70
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    Zeitschrift für anorganische Chemie 508 (1984), S. 208-208 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 71
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    Zeitschrift für anorganische Chemie 509 (1984), S. 38-52 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Phosphorus. 134. On the Triphosphanes H(t-BuP)3H' Li(t-BuP)3Li, and Me3Si(t-BuP)3SiMe3The reaction of 1,3-diiodo-1,2,3-tri-tert-butyltriphosphane, I(t-BuP)3I, with lithium aluminium hydride leads to 1,2,3-tri-tert-butyltriphosphane, H(t-BuP)3H (1). 1 reacts with n-butyllithium to 1,3-dilithium-1,2,3-tri-tert-butyltriphosphide, Li(t-BuP)3Li (2), which reacts further with trimethylchlorosilane yielding 1,3-bis(trimethylsilyl)-1,2,3-tri-tert-butyltriphosphane, Me3Si(t-BuP)3SiMe3 (3). The triphosphanes 1, 2 and 3 could be isolated in a pure state. In solution 1 forms the threo, threo and the threo,erythro configurated diastereomers 1a and 1b in a ratio of about 2:1. 3 predominantly exists in form of the threo,erythro configurated diastereomer 3b by steric reasons.
    Notes: Die Umsetzung von 1,3-Diiod-1,2,3-tri-tert-butyltriphosphan, I(t-BuP)3I, mit Lithiumaluminiumhydrid führt zu 1,2,3-Tri-tert-butyltriphosphan, H(t-BuP)3H (1). 1 reagiert mit n-Butyllithium zu 1,3-Dilithium-1,2,3-tri-tert-butyltriphosphid, Li(t-BuP)3Li (2), das mit Trimethylchlorsilan weiter zu 1,3-Bis(trimethylsilyl)-1,2,3-tri-tert-butyltriphosphan, Me3Si(t-BuP)3SiMe3 (3), umgesetzt werden kann. Die Triphosphane 1, 2 und 3 konnten in reiner Form isoliert werden. In Lösung bildet 1 die threo, threo- und threo,erythro-konfigurierten Diastereomere 1 a und 1 b im Verhältnis von etwa 2:1. 3 liegt aus sterischen Gründen hauptsächlich in Form des threo, erythro-konfigurierten Diastereomers 3 b vor.
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    Zeitschrift für anorganische Chemie 509 (1984), S. 145-152 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidation Products of Intermetallic Compounds. III. Low Temperature Forms of K2Sn2O3 and Rb2Sn2O3 and a Notice about K2Ge2O3By controlled oxidation of KSn (at 320°C) and RbSn (at 410°C) with O2 the hitherto unknown low temperature forms of K2Sn2O3 (a = 8.4100(8) Å) and Rb2Sn2O3 (a = 8.6368(8) Å) are obtained, which are isotopic with cubic K2Pb2O3. Oxidation at higher temperatures (at 510-5207°C) leads to the well-known HT-forms. The Madelung Part of Lattic Energie, MAPLE, is calculated for both compounds.K2Pb2O3, Rb2Pb2O3, Cs2Pb2O3, and Cs2Sn2O3 have been prepared too by oxidation of KPb, RbPb, CsPb, and CsSn.Oxidation of KGe (at 400°C) leads to the first oxogermanate(II), K2Ge2O3 (cubic a = 8.339(1) Å, isotypic with K2Pb2O3) together with K6Ge2O7.
    Notes: Aus KSn bzw. RbSn entstehen durch direkte Oxydation K2Sn2O3 bzw. Rb2Sn2O3 bei 320°C bzw. 410°C die bislang unbekannten „Tieftemperaturformen“ (a = 8,4100(8)Å bzw. a = 8,6368(8)Å), isotyp mit kubischem K2Pb2O3. Bei höherer Temperatur (510 bzw. 520°C) entstehen die bekannten Hochtemperaturformen.Der Madelunganteil der Gitterenergie, MAPLE, wird berechnet und diskutiert.Ebenso erhält man durch direkte Oxydation von KPb, RbPb, CsPb und CsSn die Oxide K2Pb2O3, Rb2Pb2O3, Cs2Pb2O3 und Cs2Sn2O3. Durch Oxydation von KGe wurde bei 400°C erstmals K2Ge2O3 (kubisch a = 8,339(1) Å; isotyp mit K2Pb2O3) neben K6Ge2O7 erhalten.
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    Zeitschrift für anorganische Chemie 509 (1984), S. 174-182 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Reaktion des SnCl2 mit Br2 und I2 in schwachen Donor-LösungsmittelnEs wurden die Verbindungen SnCl2Br2(MeCN)2, “Sn3Cl8Br4(THF)6” und “Sn3Cl10Br2(OEt)6” durch Reaktion zwischen SnCl2 und Br2 in Acetonitril (MeCN), Tetrahydrofuran (THF) und Diethylether (OEt2) gewonnen. Die zwei letzten Verbindungen sind feste Lösungen von SnCl4L2 und SnCl2Br2L2 (L = THF, OEt2) jeweils im Verhältnis 1:2 und 2:1. Die Verbindungen wurden mit Hilfe von IR-, Raman- und Mößbauer-Spektroskopie charakterisiert. Es wurde C1-Symmetrie für SnCl2Br2(MeCN)2 und C2v mit den Liganden in trans-Position für SnCl2Br2L2 (L = THF, OEt2) gefunden. Das bisher nicht bekannte Mößbauer-Spektrum des SnBr4(THF)2 wurde gemessen und ebenfalls die Reaktion zwischen SnCl2 und I2 in denselben Lösungsmitteln studiert. Die Bildung des SnCl4L2 (L = MeCN, THF, OEt2) SnI4 und einer kleinen Menge des SnI3Cl wurde beobachtet und Raman-spektroskopisch identifiziert.
    Notes: The compounds SnCl2Br2(MeCN)2, “Sn3Cl8Br4(THF)6”, and “Sn3Cl10Br2(OEt2)6” were obtained by reaction between SnCl2 and Br2 in acetonitrile (MeCN), tetrahydrofuran (THF) and diethyl ether (OEt2). The two last are solid solutions of SnCl4L2 and SnCl2Br2L2 (L = THF, OEt2) in the proportions 1:2 and 2:1, respectively. The compounds are characterized by IR, Raman, and Mössbauer spectroscopy, a C1 symmetry being found for SnCl2Br2 (MeCN)2 together with a C2v symmetry, with the ligands in trans positions, for SnCl2Br2L2 (L = THF, OEt2). The Mössbauer spectrum of SnBr4(THF)2 was also obtained, which has not previously been reported. The reaction between SnCl2 and I2 has also been studied in the same solvents, and the formation of SnCl4L2 (L = MeCN, THF, OEt2), SnI4, and a small amount of SnI3Cl was observed, which have been identified by Raman spectroscopy.
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  • 74
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    Zeitschrift für anorganische Chemie 509 (1984), S. 192-200 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Einige Cobalt(II)-Komplexe von 4,6-Dimethylpyrimidin-2(1H)-on (HL) wurden dargestellt und mittels IR- und Elektronenspektren magnetochemisch und konduktometrisch untersucht. Der Ligand wird über das nicht protonierte N-Ringatom angelagert und in einem Fall auch über das O-Atom der Carbonylgruppe. Die “blauen” Komplexe [CoX2 · 2HL] (X2 = Cl2, CBr, Br2, (NCS)2) und [CoX2 · 2HL] · 2HL (X = Cl, Br) haben eine verzerrte C2v-Anordnung [CoX2N2]; die Thiocyanate sind über die N-Atome an das Metall gebunden. Die „grünen“ Komplexe CoX2 · 2HL (X = Cl(4H2O), Br) besitzen eine quadratisch-pyramidale Anordnung [CoX2N2O]. Die „rosa“ Komplexe CoX2 · 4HL · nH2O (X = ClO4, n = 2, X = BF4, n = 8, CF3CO2, n = 4) und die „cremefarbigen“ CoX2 · 4HL · 6H2O (X = J, ClO4) zeigen oktaedrische Anordnung; nur CF3CO2- ist koordiniert. Die „veilchenfarbenen“ Komplexe CoAcL · 2HL · 2H2O und Co3Ac4L2 · 2HL · 2H2O haben eine mehrkernige Struktur; das Acetation betätigt sich als zweizähniger Ligand.
    Abstract: CoII-Komplexe von 4,6-Dimethylpyrimidin-2(1H)-on
    Notes: Some cobalt(II) complexes of 4,6-dimethylpyrimidine-2(1H)-one (HL) have been prepared and studied by infrared and electronic spectra and by magneto-chemical and conductometric measurements. The ligand is coordinated through the unprotonated ring-nitrogen atom and in one case also through the carbonylic oxygen atom. The “blue” complexes [CoX2 · 2HL] (X2 = Cl2, ClBr, Br2, (NCS)2) and [CoX2 · 2HL] · 2HL (X = Cl, Br) have a distorted C2v [CoX2N2] coordination; the thiocyanate ion is N-bonded to the metal. The “green” complexes CoX2 · 2HL (X = Cl(4H2O), Br) have a square-pyramidal [CoX2N2O] coordination. The “pink” CoX2 · 4HL · nH2O (X = ClO4, n = 2; X = BF4, n = 8; X = F3Ac, n = 4) and “cream” CoX2 · 4HL · 6 H2O (X = I, ClO4) complexes have an octahedral coordination; only the F3Ac- ion is coordinated. The “cyclamen” CoAcL · 2HL · 2 H2O and Co3Ac4L2 · 2HL · 2H2O complexes have a polynuclear constitution; the Ac- ion behaves as bidentate ligand.
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    Zeitschrift für anorganische Chemie 510 (1984), S. 31-36 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Raman Spectroscopic Investigations of Coordination Polymeric Metal TricyanmethanidesThe Raman spectra of 3d-metal tricyanmethanides M{C(CN)3}2 as well as of [Ni{C(CN)3}2py2] are investigated. The observed Raman lines are assigned, characteristic variations of position and intensity of these lines are discussed.
    Notes: Es werden die Ramanspektren der koordinationspolymeren 3d-Metalltricyanmethanide M{C(CN)3}2 (M = Mn, Fe, Co, Ni, Zn) sowie von [Ni{C(CN)3}2py2] untersucht. Die beobachteten Ramanlinien werden zugeordnet, charakteristische Variationen der Lage und Intensität dieser Linien werden diskutiert.
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  • 76
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    Zeitschrift für anorganische Chemie 510 (1984), S. 51-60 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 34. Vapor Pressure Measurements in the Europium-Phosphorus SystemThe vapor pressure of the europium phosphides EuP7, α-EuP3, ß-EuP3, EuP2 and Eu3P4 were measured using the Knudsen-Effusion technique. These compounds were vaporized incongruently according to the general reaction a EuPm, (s) = a EuPn, (s) + P4, (g) where a (m - n) = 4. The following enthalpies and entropies of reaction were calculated (δH)kJ · mol-1/δS (J · K-1 mol-1)/ T(K). [δH/δS/T]: EuP7 → ß-EuP3 [191/215/698]; α-EuP3 → EuP2 [212/162/847]; ß-EuP3 → EuP2 [261/212/847]; EuP2 → Eu3P4 [209/144/868]; Eu3P4 → EuP [240/131/1110]. The temperature and pressure ranges over which these phosphides exist were determined from the above values. Standard enthalpies of formation relative to EuP(s) were calculated by combining different reaction enthalpies. The results demonstrate the relatively high stability of ß-EuP3, EuP7 and the instability of EuP2.
    Notes: Für die Europiumphosphide EuP7, α-EuP3, ß-EuP3, EuP2 und Eu3P4 wurden die Dampfdrucke der inkongruenten Verdampfungsreaktionen a EuPm, (f) = a EuPn, (f) + P4, (g) mit a(m - n) = 4 mit der Knudsen-Methode gemessen. Zur Abspaltung von einem Mol P4,(g) wurden bei den mittleren Temperaturen T(K) die folgenden Reaktionsenthalpien δH(kJ · mol-1) und Reaktionsentropien δS(J · K-1 · mol-1) erhalten: [δH/δS/T]: EuP7 β ß-EuP3 [191/215/698]; α-EuP3 → EuP2 [212/162/847]; ß-EuP3 → EuP2 [261/212/847]; EuP2 → Eu3P4 (209/144/868); Eu3P4 → EuP [240/131/1110]. Hierdurch wurden die Existenzfelder der verschiedenen Europiumphosphide in Abhängigkeit von Druck und Temperatur festgelegt. Durch Kombination der verschiedenen Reaktionsenthalpien werden die Standardbildungsenthalpien der Phosphide relativ zu EuP berechnet. Sie zeigen die hohe Stabilität von ß-EuP3 und EuP7 sowie die Instabilität von EuP2.
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    Zeitschrift für anorganische Chemie 508 (1984), S. 86-92 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of (PPh4)2[Mo2Cl10]The title compound is obtained in the reaction of [MoCl4(Ph—C≡C—Ph)]2 with tetraphenylphosphonium chloride in dichloro methane, forming brown crystals. It is characterized by the i.r. spectrum and a crystal structure analysis by the aid of X-ray diffraction data. The complex crystallizes triclinic in the space group P1 with one formula unit per unit cell. The cell dimensions are a = 1122 pm, b = 1137 pm, c = 1283 pm; α = 63.4°, β = 69.1°, γ = 86.5°. The crystal structure determination (2959 observed, independent reflexions, R = 4.5%) shows the constants of the unit cell to consist of on centrosymmetric anion, two cations and one disordered molecule of dichloro methane. The distance Mo—Mo in the anion is 380 pm, which excludes direct magnetic interaction between the molybdenum atoms.
    Notes: Die Titelverbindung entsteht in Form brauner Kristalle durch Umsetzung von [MoCl4(Ph—C≡C—Ph)]2 mit Tetraphenylphosphoniumchlorid in Dichlormethan; sie wird durch das IR-Spektrum und durch eine Kristallstrukturbestimmung charakterisiert. Der Komplex kristallisiert triklin in der Raumgruppe P1 mit einer Formeleinheit pro Elementarzelle. Die Zellparameter betragen a = 1122 pm, b = 1137 pm, c = 1283 pm, α = 63,4°, β = 69,1°, γ = 86,5°. Die röntgenographische Kristallstrukturbestimmung (2959 beobachtete, unabhängige Reflexe, R = 4,5%) zeigt, daß die Struktur aus zentrosymmetrischen, dimeren Anionen, isolierten Kationen, und einem fehlgeordneten Molekül Dichlormethan pro Elementarzelle besteht. Der Mo—Mo-Abstand im Anion beträgt 380 pm, was eine direkte magnetische Wechselwirkung zwischen den Mo-Atomen ausschließt.
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    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal and Molecular Structure of Tris(diethyldithiocarbamato)dimethylphenylphosphinetechnetium (III)The title compound Tc(S2CNEt2)3(Me2PhP) I has been prepared by the reaction of TcCl3(Me2PhP)3 with NaS2CNEt2. The crystal structure of I has been determined by single-crystal X-ray diffraction methods at room temperature. Crystals are rhombic, space group P212121, with a = 8.708(1), b = 12.012(1), c = 29.626(3) Å and Z = 4. The compound consists of discrete I molecules. The technetium atom has a seven-coordinated environment which is best described as a distorted pentagonal bipyramid. The Tc - P distance (2.330(3) Å) is remarkably short compared with other technetium complexes with mono-dentate phosphine ligands.
    Notes: Die Titelverbindung Tc(S2CNEt2)3(Me2PhP) I wurde durch Reaktion von TcCl3(Me2PhP)3 mit NaS2CNEt2 dargestellt und ihre Kristall- und Molekülstruktur durch Röntgenstrukturanalyse ermittelt. Die Kristalle sind rhombisch, Raumgruppe P212121, mit a = 8,708(1), b = 12,012(1), c = 29,626(3) Å und Z = 4. Die Verbindung besteht aus diskreten monomeren Molekülen. Das Technetiumatom hat siebenfache Koordination, die am besten als geringfügig verzerrte pentagonale Bipyramide beschrieben werden kann. Die Tc - P-Bindungslänge (2,330(3) Å) ist bemerkenswert kurz im Vergleich zu anderen Technetiumkomplexverbindungen mit einzähnigen Phosphanen.
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    Zeitschrift für anorganische Chemie 510 (1984), S. 152-162 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermodynamics and Structure of Molten Mixtures Alkali Halide-Alkaline Earth HalideThermodynamic quantities ai, fi, GE, and SE were calculated on the basis of vapour pressures of molten mixtures of the type alkali halide-alkaline earth halide. Negative deviations from ideality were found in all systems. The influence of cations or anions on the properties of mixtures is discussed. There is a good correlation between GE and the change of polarization energy δEp. Strong ionic interactions were found in molten mixtures, especially in the system RbBr - CaBr2. The existence of stable complex ions in melts could not be shown by Raman spectroscopy.
    Notes: Aus den Dampfdrücken der geschmolzenen Mischungen vom Typ Alkalimetallhalogenid-Erdalkalimetallhalogenid wurden die thermodynamischen Daten ai, fi, GE sowie Orientierungswerte für SE berechnet. In allen Systemen treten z. T. beträchtliche negative Abweichungen von der Idealität auf. An ausgewählten Beispielen wird der Einfluß der Kationen bzw. Anionen auf die Mischungseigenschaften diskutiert. Für die GE-Werte ergibt sich eine gute Korrelation mit der Änderung der Polarisationsenergie δEp. Ramanspektroskopische Untersuchungen konnten die Existenz stabiler komplexer Ionen nicht belegen, weisen aber besonders bei den Mischungen RbBr - CaBr2 auf starke interionische Wechselwirkungen hin.
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    Zeitschrift für anorganische Chemie 510 (1984), S. 189-193 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die binären und ternären Gleichgewichte im System MoO3 - TeO2 - Al2O3 wurden rötgenographisch untersucht. Bei 750°C in Luft wurden in diesem System die im Abstract angegebenen koexistierenden Bereiche gefunden. Eine Bildung ternärer Verbindungen konnten im untersuchten Temperaturbereich (450 - 750°C) nicht beobachtet werden.
    Notes: The binary and ternary equilibrium reactions of Al2O3 with TeO2 and MoO3 were studied by X-ray diffraction methods and the following compatibility ranges were determined in the TeO2 - MoO3 - Al2O3 system at 750°C in air: TeO2, Te2MoO7, Al2TeO6; Te2MoO7, MoO3, Al2TeO6; MoO3, Al2(MoO4)3, Al2TeO6; Al2(MoO4)3, Al2O3, Al2TeO6. Ternary compound formation was not observed in the temperature range investigated (450 - 750°C).Phasengleichgewichte im System MoO3 - TeO2 - Al2O3.
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  • 81
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Spectroscopic Studies of 15N Labelled N-Phosphorylphosphazenes and Imidodiphosphoric Acid Derivatives15N labelled compounds were prepared and investigated by means of 31P- and 15N-NMR spectroscopy. The chemical shift values δP and δN, and the coupling constants 1JPN and 2JPP are discussed and interpreted qualitatively by semiempirical quantumchemical calculations (CNDO/2) using POPLE'S ΔE-model.
    Notes: 15N-markierte Verbindungen der Substitutionsreihen wurden synthetisiert und mit Hilfe der 31P- und 15N-NMR-Spektroskopie untersucht. Die chemischen Verschiebungen δP und δN sowie die Kopplungskonstanten 1JPN und 2JPP werden diskutiert und qualitativ mit Hilfe halbempirischer quantenchemischer Rechnungen (CNDO/2) im Rahmen des POPLE-schen ΔE-Modells interpretiert.
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  • 82
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of the Two-component System Triethylphosphite/Carbon Tetrachloride with Nucleophiles Containing Hydrogen. 1. Reaction with Acyl AmidesAcyl amides react with the two-component system triethylphosphite/carbon tetrachloride yielding N-acyl phosphazenes, (EtO)3P=N—Ac. In this way (EtO)3P=N—P(O)(OEt)2, (EtO)3P=N—CN, (EtO)3P=N—C(O)Ph, and (EtO)3P=N—SO2Ph were prepared. Ethyl esters of phosphoric acid and trichloromethane phosphonic acid were obtained as by-products.
    Notes: Säureamide reagieren mit dem Zweikomponentensystem Triethylphosphat/Tetrachlorkohlenstoff zu N-Acylphosphazenen, (EtO)3P=N—Ac. Auf diese Weise wurden aus entsprechenden Amiden (EtO)3P=N—P(O)(OEt)2, (EtO)3P=N—CN, (EtO)3P=N—C(O)Ph und (EtO)3P=N—SO2Ph dargestellt. Als Nebenprodukte werden Phosphorsäureethylester und Trichlormethanphosphonsäureester erhalten.
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  • 83
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Discrete Polynuclear Metal Complexes from Polysulfide Solutions: [Cu6S17]2-, a Novel Binary Polynuclear CuI Complex with Several Remarkable Structural FeaturesThe complex [Cu6S17]2-, obtained from Cu(acac)2 and an ethanolic polysulfide solution, contains an unusual arrangement of the metal atoms and novel types of ligand coordination, particularly of polysulfido (S42- and S52-) ions. The relevance of the synthesis with respect to the “dilemma of transporting metals together with sulfur” for the process of metal sulfide rock formation is evidenced. (PPh4)2[Cu6S17] crystallizes in the space group C2/c with Z = 4 (for further details see Inhaltsübersicht).
    Notes: Der Komplex [Cu6S17]2-, der als Tetraphenylphosphonium-Salz (1) aus Cu(acac)2 und einer ethanolischen Polysulfidlösung erhalten wurde, zeigt eine ungewöhnliche Anordnung der Metall-Atome und eine neuartige Koordination von Polysulfidoliganden (S42- und S52-). Auf die Relevanz der Synthese bezüglich der Problematik der Entstehung von Metall-Sulfid-Mineralien wird hingewiesen. 1 kristallisiert monoklin in der Raumgruppe C2/c mit Z = 4 (Gitterdimensionen a = 20,270(7), b = 11,605(5), c = 26,331(9) Å, β = 109,68(4)°).
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  • 84
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    Zeitschrift für anorganische Chemie 511 (1984), S. 108-131 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Organosilicon Compounds. 97. About the Influence of the Si-Substituents (Me, Cl) upon the Formation and the Reactions of Ylides1,3-disilapropanes with different grade of chlorination or methylation at the silicon atoms and containing a CCl2 group cleave the Si—P bond of Me3SiPMe2. By subsequent rearrangement ylides with = PMe2Cl group are formed. The reactivity of the CCl2 group depends on the grade of Si-chlorination resp. Si-methylation. Si-methylation decreases the reactivity of the CCl2 group. The reaction of 1,3-disilapropanes and Me3SiPMe2 (molar ratio 1:1) runs in a sequence shown in “Inhaltsübersicht”. Ylid C is able either to react with the initial compound A forming B, or in competition decomposes forming D. Reacting Si-perchlorinated carbosilanes, the decomposition forming D is not to be observed. In Si-methylated ylides like (Me3Si)2C=PMe2—PMe2 and (Me3Si)2C=PMe2—P(Me)SiMe3 the ylid carbon atom is able to abstract a proton of the P—CH3 group resp. P—H groups of the trivalent phosphorus forming (Me3Si)2C(H)PMe2. The rearrangement is proved by deuterated derivatives. The different behaviour is due to the increased basicity of the ylid-C atom in Si-methylated phosphorus ylides. Quite the same behaviour show the phosphorus ylides of 1,3,5-trisilacyclohexane.
    Notes: Die am Si-Atom unterschiedlich chlorierten und methylierten 1,3-Disilapropane mit der CCl2-Gruppe ermöglichen die Spaltung von Me3Si—PMe2 unter Bildung der P-halogenierten Phosphorylide, wobei mit steigendem Methylierungsgrad die Reaktivität abnimmt. Die Umsetzungen verlaufen in folgender Reaktionsfolge: Das Ylid C kann mit der nicht umgesetzten Ausgangsverbindung A zu B zurückreagieren oder es zersetzt sich in einer Konkurrenzreaktion zu D. Bei Si-chlorierten Yliden wird die Bildung von D nicht beobachtet. In Si-methylierten Yliden wie (Me3Si)2C=PMe2—PMe2 und (Me3Si)2C=PMe2—P(Me)SiMe3 vermag das Ylid-C-Atom ein H-Atom aus der P—CH3-Gruppe oder der PH-Gruppe des dreibindigen Phosphors zu abstrahieren unter Bildung von (Me3Si)2C(H)PMe2. Die Umlagerung wird anhand deuterierter Derivate belegt. Das unterschiedliche Verhalten wird auf die erhöhte Basizität des Ylid-C-Atoms in den Si-methylierten Phosphoryliden zurückgeführt. Ganz entsprechend verhalten sich die Phosphorylide 1,3,5-Trisilacyclohexans.
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  • 85
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    Zeitschrift für anorganische Chemie 511 (1984), S. 176-184 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polymorphism of SrTa2O6Orthorhombic SrTa2O6 is a new low temperature modification related to orthorhombic CaTa2O6. SrTa2O6(orh.) was obtained when the wellknown modification SrTa2O6(TTB) which is related to the tetragonal tungsten bronzes was heated in the presence of a transporting agent (chlorine) or a mineralizer (melt of B2O3) at temperatures below 1150°C. It could be prepared by the reaction of a 1:1 mixture of Sr(NO3)2 or SrCO3 with Ta2O5 in a sealed quartz glass tube as well. SrTa2O6(orh.) also occurred as an intermediate phase of the reaction of the corresponding 1:2 mixture at temperatures below 900°C (e. g. 840°C). Indexing of Guinier powder patterns led to the following unit cell: a = 11.006 Å, b = 7.638 Å, c = 5.622 Å. At temperatures above 1220°C SrTa2O6(orh.) changes (in air) to SrTa2O6(TTB). A reversal of this transition could not be achieved without the presence of a mineralizer or a transporting agent. CaxSr1-xTa2O6 solid solutions of the low temperature form could not definitely be established. However, at 1300°C solid TTB solutions of CaxSr1-xTa2O6 were formed. For x 〉 0.05 the TTB unit cells are orthorhombically distorted. For x ≥ 0.85 the x-ray powder patterns of the solid solutions looked like the one of CaTa2O6(orh.) and no TTB-structure was observed at 1300°C.
    Notes: Von SrTa2O6 wurde eine neue, mit orthorhombischem CaTa2O6 strukturverwandte Tieftemperatur-Modifikation erhalten. SrTa2O6(orh.) ließ sich bei Temperaturen unter 1150°C sowohl aus der bisher bekannten, den tetragonalen Wolframbronzen verwandten Modifikation SrTa2O6(TWB) in Gegenwart eines Transportmittels (Chlor) bzw. eines Mineralisators (B2O3-Schmelze), wie auch durch Umsetzen von Gemengen (1:1) aus SrCO3 oder Sr(NO3)2 und Ta2O5 in geschlossenen Quarzglasampullen erhalten. Auch als Zwischenprodukt der Umsetzung entsprechender 1:2-Gemenge bei Temperaturen unter 900°C (z. B. 840°C) tritt diese Modifikation auf. Die Gitterkonstanten von SrTa2O6(orh.) sind aufgrund von Pulverdaten: a = 11,006 Å, b = 7,638 Å, c = 5,622 Å. Beim Erhitzen auf etwa 1 220°C (an der Luft) wandelt sich SrTa2O6(orh.) in SrTa2O6(TWB) um. Eine Rückumwandlung von SrTa2O6(TWB) in SrTa2O6(orh.) ohne Mineralisator- oder Transportmittelzusatz war nicht zu erreichen. Mischkristalle CaxSr1-xTa2O6 der Tieftemperaturform ließen sich nicht sicher nachweisen. Die bei Mischkristallen mit 0,05 〈 x ≤ 0,20 (1300°C) vorliegende TWB-Struktur ist orthorhombisch verzerrt. CaTa2O6(orh.) zeigte dagegen ab x ≥ 0,85 (1300°C) keine Entmischung.
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  • 86
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    Zeitschrift für anorganische Chemie 509 (1984), S. 167-173 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation, Isolation, and Characterization of Mixed Thiocyanato(1.3-diaminopropane) -chromium(III) ComplexesThe complexes [Cr(NCS)4dap]- and trans-[Cr(NCS)2(dap)2]+ (dap = 1.3-diaminopropane) are prepared for the first time, isolated as salts and characterized by CHN analysis, chromium contents, the electrophoretic behaviour in dimethylformamide, and by UV, VIS, and IR spectra.
    Notes: Die Komplexe [Cr(NCS)4dap]- und trans-[Cr(NCS)2(dap)2]+ (dap = 1,3-Diaminopropan) werden erstmals dargestellt, als Salze isoliert und durch CHN-Analyse, Chrombestimmung, elektrophoretisches Verhalten in Dimethylformamid sowie Spektren im UV, VIS und IR charakterisiert.
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  • 87
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    Zeitschrift für anorganische Chemie 509 (1984), S. 201-208 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Schwefel-Stickstoff-Chelatbildner. IV. Einige Kupfer(II)-Komplexe von Thioaminopyridinen. IR- und ReflexionsspektroskopieEine Reihe von CuII-Komplexen sind dargestellt und charakterisiert worden. Die angenommenen Strukturen beruhen auf ihren IR -und VIS-Spektren. Die Thioaminopyridine können in verschiedener Weise koordiniert sein. Im Gegensatz zu unseren Befunden an aliphatischen Thioaminen ergab sich kein Zusammenhang zwischen der Struktur der CuLX2-Verbindungen und der Art des X--Anions. Ein Hinweis auf die Struktur der CuL2+-Komplexe in wäßriger Lösung kann aus festem CuLX2 nicht erhalten werden.
    Notes: A series of solid state CuII complexes with thia-aminopyridines . S(CH2)mNH2 have been prepared and characterized. The postulated structures of these CuLX2 (X = OAc-, NO3-, ClO4- or Cl-) compounds were based on their I.R. and electronic spectra. It was found that the thiaaminopyridines may coordinate in quite different ways. In contrast with what was found for the aliphatic thiadiamines, no relation was stated between the structure of the CuLX2 compounds and the nature of the X- anion.Moreover the solid state compounds do not give a clear indication for the structure of the CuL2+ species in aqueous solution.
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  • 88
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    Zeitschrift für anorganische Chemie 510 (1984), S. 199-207 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermochemische Eigenschaften und Aufwachsen von Hg1-xCdxTe auf CdTeNach thermodynamischen Rechnungen enthält die Gasphase des epitaktischen Hg1-xCdxTe - HgI2 - CdTe Systems vorwiegend Hg(g) und HgI2(g) durch die andere Moleküle vom Ausgangsstoff zum CdTe Substrat wandern. Transportversuche im Temperaturgradienten 590° → 535°C zeigten, daß man dünne Schichten von Hg1-xCdxTe auf CdTe von einem ternären Ausgangsmaterial in Gegenwart von HgI2 erhält.
    Notes: Based on a thermodynamic analysis, the vapor phase of the Hg1-xCdxTe - HgI2 - CdTe epitaxy system consists predominantly of Hg(g) and HgI2(g) through which nutrient species migrate from the source to the CdTe substrate. Growth experiments in the 590° → 535°C temperature gradient showed that Hg1-xCdxTe layers can be grown on CdTe substrates using a preannealed, ternary source material in the presence of HgI2.
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  • 89
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical Transport Reactions of Ni-Sulfides and Some Relationships in C.T.R. of Complex Solids in the Case of Sulfides of Fe, Co, NiCrystals of α-Ni3S2, NiS, and NiS2 as well as solid solutions Fe1-yNiySx were grown by C.T.R. The coexistence equilibrium pressure of the solution equilibrium pressure p(S2), the activity of the metal component, the stability of gaseous metal halides concerning decomposition as well as their stability related on the transport agent have to be taken into account to choose a suitable transport agent, which have a sometimes opposite influence on the transport behaviour. Halogenes, hydrogen halides, and GeI2 were used as transport medium.
    Notes: Durch chemische Transportreaktionen wurden Kristalle der Phasen α-Ni3S2, NiS und NiS2 sowie Mischkristalle Fe1-yNiySx erhalten. Bei der Auswahl des Transportmittels sind der Koexistenzzersetzungsdruck bzw. Löslichkeitsdruck p(S2) und die Metallaktivität im Bodenkörper, die Stabilität der gasförmigen Metallhalogenide bezüglich Zerfall und ihre Stabilität relativ zum Transportmittel zu beachten, die z. T. gegenläufigen Einfluß haben. Geeignete Transportmittel sind Halogene, Halogenwasserstoffe und GeI2.
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  • 90
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    Zeitschrift für anorganische Chemie 511 (1984), S. 57-71 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical Transport of Zinc Oxide and the Estimation of its Phase WidthThe chemical transport behaviour of zinc oxide using different transport agents and the influence of the transport conditions (T, ΔT, p) on transport rate and deposition form was studied. The range of homogeneity of ZnO is very narrow. The best agents for deposition of ZnO with the upper phase boundary are Cl2 and Br2, for the deposition of the lower phase boundary HBr and NH4Br are more suitable. The deviation from stoichiometry depends on the deposition temperature and amounts to 10 till 250 ppm in the range of 1073 up to 1373 K.
    Notes: Das chemische Transportverhalten von Zinkoxid mit Cl2, Br2, HCl, HBr, NH4Cl und NH4Br und der Einfluß der Transportbedingungen (T, ΔT, p) auf die Abscheidungsgeschwindigkeit und Abscheidungsform wurde studiert. ZnO weist ein sehr schmales Homogenitätsgebiet auf. Zur Abscheidung von ZnO der oberen Phasengrenzzusammensetzung sind Cl2 und Br2 am besten geeignet. Für die Abscheidung von ZnO der unteren Phasengrenzzusammensetzung sind am besten HBr und NH4Br geeignet. Die Abweichung von der Stöchiometrie hängt von der Präparationstemperatur der Kristalle ab und liegt zwischen 10 und 250 ppm im Temperaturbereich 1073 bis 1373 K.
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  • 91
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    Zeitschrift für anorganische Chemie 511 (1984), S. 89-94 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXXVIII. Reactions of Dibenzyl Manganese with Oxygene(C6H5CH2)2Mn · C4H8O2 reacts with oxygen forming an unstable deep violet compound which changes in a stable unsoluble yellow peroxide of the formula C6H5CH2MnO—OMnCH2C6 H5. With excess oxygen a polynuclear complex of 3 valent manganese is formed with the composition Mn4O4(OH)4(OCHC6H5)2.The compounds isolated were characterized by the products of hydrolyses and thermolyses, anaerobic reaction with iodine, magnetic moments, i.r. and e.s.r. spectra.
    Notes: Dibenzylmangan-1,4-dioxan reagiert mit Sauerstoff zu einer tiefvioletten instabilen Substanz. Diese wandelt sich in ein stabiles gelbes, schwerlösliches Peroxid der Formel C6H5CH2MnO—OMnCH2C6H5 um. Mit überschüssigem Sauerstoff entsteht daraus ein Mehrkernkomplex des 3wertigen Mangans der Zusammensetzung Mn4O4(OH)4(OCHC6H5)2.Die isolierten Verbindungen wurden durch ihre Hydrolyse- und Thermolyseprodukte, anaerobe Iodierung, magnetischen Momente sowie IR- und ESR-Spektren näher charakterisiert.
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  • 92
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    Zeitschrift für anorganische Chemie 508 (1984) 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 93
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    Zeitschrift für anorganische Chemie 508 (1984), S. 19-25 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Structure of Antimony (III) Tris (thiophosphinates)The title compounds are formed by the reaction of Sb(CH3COO)3 with thiophosphinic acids R2P(=S)OH (R = CH3 cyclo-C6H11, C6H5). The crystal and molecular structures of Sb((cyclo-C6H11)2POS)3 and Sb((C6H5)2POS)3 have been determined by single crystal X-ray methods. SbIII is pyramidally coordinated to the oxygen atoms of the R2POS ligands through short (primary) bonds with a mean length of 203 pm. The Sb—S distances of the mainly chelating ligands vary between 300 and 320 pm (secondary bonds). The lone electron pair is stereochemically active.
    Notes: Die Umsetzung von Sb(CH3COO)3 mit Thiophosphinsäuren R2P(=S)OH (R = CH3, cyclo-C6H11, C6H5) führt zu Verbindungen der Formel Sb(R2POS)3. Die Strukturen der Verbindungen mit R = cyclo-C6H11 und C6H5 wurden an Einkristallen röntgenographisch bestimmt. SbIII ist über kurze (primäre) Bindungen mit der mittleren Länge von 203 pm pyramidal an die Sauerstoffatome der R2POS-Liganden gebunden. Die Sb—S-Abstände (sekundäre Bindungen) sind ungefähr 320 pm lang. Das freie Elektronenpaar ist stereochemisch aktiv.
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  • 94
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    Zeitschrift für anorganische Chemie 508 (1984), S. 43-49 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: I.R. and Mass Spectroscopic Investigations on α,ω-Dihydrochloro Silanes H(SiCl2)nH with n = 3-7Mass spectra of α,ω-dihydrochlorosilanes H(SiCl2)nH were analyzed respecting to their fragmentation. This shows, that the cleavage starts with the break of SiSi bonds, by preference in the middle of the chain. This is in accordance to the results of IR spectra which show very similar frequencies like perchlorooligo silanes. Thus, the lowest force constants of SiSi bondings in α,ω-dihydrochloro silanes, can be also expected in the middle of the chain.
    Notes: Die Massenspektren der α,ω-Dihydrochlorsilane H(SiCl2)nH mit n = 3-7 werden bezüglich ihrer Fragmentierung analysiert. Es zeigt sich, daß die Spaltung mit einem Zerbrechen der SiSi-Bindung, vorzugsweise in der Mitte der Kette beginnt. Dies steht im Einklang mit den Ergebnissen der IR-Spektren, die sehr ähnliche Frequenzen zeigen, wie bei den Perchlorsilanen gefunden. Daraus kann geschlossen werden, daß auch bei den α,ω-Dihydrochlorsilanen die mittleren SiSi-Bindungen die kleinsten Kraftkonstanten zeigen.
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  • 95
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phase Determinations by X-rays on the Thermal Dissociation and the Hydrolysis of Alkali Hexafluorogermanates at Higher TemperaturesFor a better understanding of the thermal dissociation of alcaline hexafluorosilicates investigations have been done on hexafluorogermanates. In these systems the formation of new phases has been studied by x-rays in dependence of temperature. Thermal behaviour of the substances strongly depends on the starting structure. Phase transformations taking place at lower temperatures are strongly determine the reaction at higher temperature. Therefore, we found differences to the analogous thermal reactions of hexafluorosilicates.There is a high sensitivity to hydrolysis of hexafluorogermanates above 600°C. We discuss the difference in reaction of thin powder layers and of powder samples in the volume.
    Notes: Zum besseren Verständnis des thermischen Verhaltens von Alkalihexafluorosilicaten wurden Vergleiche mit analogen Germanium-Verbindungen angestellt. Die Phasenneubildung wurde als Funktion der Temperatur röntgenographisch untersucht. Es ergab sich eine starke Abhängigkeit des thermischen Verhaltens von der Ausgangsstruktur. Phasentransformationen, die bei niederen Temperaturen ablaufen, beeinflussen bei höherer Temperatur das Reaktionsgeschehen (thermische Vorgeschichte der Substanz). Deshalb resultieren gegenüber den Hexafluorosilicaten differierende Reaktionsabläufe. Durch Heizguinieraufnahmen unter getrocknetem, strömendem Inertgas wurde die enorme Hydrolysenempfindlichkeit der Hexafluorogermanate oberhalb 600°C bewiesen.Das unterschiedliche Verhalten von dünnen Pulverschichten und kompakten Pulverproben wird diskutiert.
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  • 96
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Organosilicon Compounds. 99. Separation of Carbosilane and Silylphosphane Mixtures by Means of HPLCTest mixtures of Si-methylated carbosilanes were separated by means of reversedphase HPLC (nucleosil 5-C18; CH3OH:hexane = 90:10). The corresponding SiCl-containing mixtures were successfully separated only after reductin of the SiCl groups by means of LiAlH4 (CH3OH: C6H6 + H2O = 92.5:7.5 + 4 - 8%). A model separation of the silylphosphanes Me3SiPH2, (Me3Si)2PH and (Me3Si)3P using the same material but acetonitrile: toluene = 85:15 is also reported.
    Notes: Testgemische Si-methylierter Carbosilane werden mit reversed-phase HPLC getrennt (Nucleosil 5-C18; CH3OH:Hexan = 90:10). Die Auftrennung entsprechender SiCl-haltiger Verbindungen gelingt nach Reduktion der SiCl-Gruppen mit LiAlH4 (CH3OH: C6H6 + H2O = 92,5: 7,5 + 4 - 8%). Über die Modelltrennung der Silylphosphane Me3SiPH2, ((Me3Si)2)2PH und (Me3Si)3P unter Verwendung des gleichen Säulenmaterials, jedoch mit dem Eluens Acetonitril: Toluol = 85:15, wird ebenfalls berichtet.
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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 512 (1984), S. 177-180 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactivity of Intramolecular Basestabilized Tin(II) Compounds with Halogens, Tin Tetrachloride, and TrichloromethaneIntramolecular basestabilized tin(II) compounds of the type RN(CH2CH2Y)2Sn (Y = O, S and R = Me, t-Bu) react with halogens, tin tetrachloride, and trichloromethan at room temperature by oxydative addition reaction to tin(IV) derivatives. These compounds are characterized by n.m.r. investigations and by Mössbauer studies.
    Notes: Intramolekular basenstabilisierte Zinn(II)-Verbindungen des Typs RN(CH2CH2Y)2Sn (Y = O, S und R = Me, t-Bu) reagieren bei Raumtemperatur mit Halogenen, Zinntetrachlorid und Chloroform im Sinne von oxydativen Additionsreaktionen zu Zinn(IV)-Derivaten. Diese Derivate werden durch NMR-Untersuchungen und durch Mößbauerstudien charakterisiert.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 512 (1984), S. 231-239 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 137. Alkyl Esters of Isothiocyanoformic, Isothiocyanomonothioformic and Isothiocyanodithioformic AcidsThe esters RO—CO—NCS, where R = CH3, C2H5, as well as RS—CO—NCS and RS—CS—NCS with R = C2H5, nC3H7 have been prepared by three different methods. The reaction between the corresponding chloro compound and KSCN in the presence of the phase transfer catalyst 18-crown-6 gives the highest yields.The electron absorption, infrared, nuclear magnetic resonance, and mass spectra of these compounds are reported.
    Notes: Die Ester RO—CO—NCS mit R = CH3, C2H5 sowie RS—CO—NCS und RS—CS—NCS mit R = C2H5, nC3H7 wurden nach drei verschiedenen Verfahren hergestellt, wobei die Umsetzung der entsprechenden Chloroverbindung mit KSCN in Gegenwart des Phasentransferkatalysators 18-Krone-6 die besten Ausbeuten erbringt.Die Elektronenabsorptions-, Infrarot-, kernmagnetische Resonanz- und Massenspektren der Verbindungen werden mitgeteilt.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 508 (1984), S. 191-196 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Coordination and Extraction of Molybdenum(VI) with Bidentate LigandsA series of bidentate ligands as well as their thio derivatives from the groups of 8-quinolinols, β-diketones, acylpyrazolones, and N-acyl-phenylhydroxylamines was studied for the ability to extract molybdenum(VI) from heptamolybdate. The extraction principally runs only in acidic medium, sulfur-containing extractants having no advantage. The composition of the complexes was determined by the isolation of compounds in the solid state and also by the interpretation of distribution data.
    Notes: Eine Reihe zweizähniger Liganden sowie entsprechende Thioderivate aus den Gruppen der 8-Hydroxychinoline, β-Diketone, Acylpyrazolone und N-Acyl-phenylhydroxylamine wurde auf ihr Extraktionsvermögen für Molybdän aus Heptamolybdat geprüft. Die Extraktion ist grundsätzlich nur im sauren Bereich möglich, schwefelhaltige Extraktionsmittel bringen keine Vorteile. Die Komplexzusammensetzung wurde durch Isolierung von Komplexen in Substanz und durch Auswertung der Verteilungsdaten ermittelt.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 508 (1984), S. 201-207 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Silicon-Sulphur Compounds. XXIX. 29Si-N.M.R. InvestigationsThree series of silicon-sulphur compounds (RO)3SiSR′ (I), (i-PrO)4-nSi(SEt)n (II) and cyclic Si—S compounds (III) were prepared, some of them at the first time and their 29Si-N.M.R. spectra were measured. In the series of trialkoxysilylthio derivatives (I) were the steric and inductive effects of the RO and R'S groups evaluated. In the series II were the 29Si-N.M.R. chemical shifts related to the relative paramagnetic screening constants σ* and netto charge at the silicon atom q(Si) using the EN-quantum-chemical model discussed. In the series III were the shift contribution of the (SiS)2 and 1-sila-2,5-dithiacyclopentan rings determined.
    Notes: Drei Reihen von Silicium-Schwefel-Verbindungen: (RO)3SiSR'(I), (i-PrO)4-nSi(SEt)n (II) und cyclische Si—S-Verbindungen (III) wurden dargestellt, davon einige erstmalig, und ihre 29Si-NMR-Spektren vermessen. In der Reihe der Trialkoxysilylthio-Derivate (I) wurden die sterischen und induktiven Wirkungen der RO- und R'S-Gruppen abgeschätzt. In der Reihe II wurden die 29Si-NMR-chemischen Verschiebungen in Abhängigkeit von den relativen paramagnetischen Abschirmungskonstanten σ* und der Nettoladung am Silicium q(Si) im Rahmen des EN-quantenchemischen Modells diskutiert. In der Reihe III wurden die Beiträge des (SiS)2-und 1-sila-2,5-dithia-cyclopentan-Rings zur chemischen Verschiebung ermittelt.
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