ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • LUNAR AND PLANETARY EXPLORATION  (1,281)
  • FLUID MECHANICS AND HEAT TRANSFER  (866)
  • EARTH RESOURCES AND REMOTE SENSING  (830)
  • Atomic, Molecular and Optical Physics
  • Physics
  • 2010-2014
  • 1990-1994  (1,703)
  • 1980-1984  (2,379)
  • 1925-1929
  • 1990  (1,703)
  • 1980  (2,379)
Collection
Keywords
Publisher
Years
  • 2010-2014
  • 1990-1994  (1,703)
  • 1980-1984  (2,379)
  • 1925-1929
Year
  • 1
    facet.materialart.
    Unknown
    The meaning of hydrophobicity (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-10-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dill, K A -- New York, N.Y. -- Science. 1990 Oct 12;250(4978):297-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco 94143.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2218535" target="_blank"〉PubMed〈/a〉
    Keywords: Energy Transfer ; Physical Phenomena ; Physics ; *Protein Conformation ; Proteins/*chemistry ; Solutions
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    An error analysis of least-squares finite element method of velocity-pressure-vorticity formulation for Stokes problem (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A theoretical proof of the optimal rate of convergence for the least-squares method is developed for the Stokes problem based on the velocity-pressure-vorticity formula. The 2D Stokes problem is analyzed to define the product space and its inner product, and the a priori estimates are derived to give the finite-element approximation. The least-squares method is found to converge at the optimal rate for equal-order interpolation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computer Methods in Applied Mechanics and Engineering (ISSN 0045-7825); 84; 3, De
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Uranus - The planet, rings and satellites (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The present overview of available data regarding Uranus and its planetary structures encompasses ground- and space-based observations of the planet with specific attention given to the interpretation of Voyager 2 data. A brief examination of historical observations is given which includes its discovery, position determination, and the related discoveries of Uranus' five large satellites and rings. The observational data preceding the Voyager 2 mission are reviewed in terms of the planetary interior, atmosphere, and magnetosphere. The Voyager 2 mission is given detailed treatment with descriptions of NASA's development and deployment of the spacecraft as well as detailed data from the Uranus encounter. Reference is given to structure and composition of Uranus' atmosphere, valid models of the interior, and wave-particle interactions in the magnetosphere. The structures of the rings and satellites are examined with reference to specific observational requirements from future missions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Experimental and computational surface and flow-field results for an all-body hypersonic aircraft (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Personnel from NASA Ames Research Center presented a paper on establishing a benchmark experimental data base for generic hypersonic vehicle shape for validation and/or calibration of advanced computational fluid dynamics computer codes. The need for this capability is based on a requirement for extensive hypersonic data to fully validate CFD codes to be used for NASP and other hypersonic vehicles. The use of wind tunnel models in the Ames 3.5-ft Hypersonic Wind Tunnel to obtain pertinent surface and flow-field data over a broad range of test conditions is described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, 2nd NASA CFD Validation Workshop; p 126-161
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    NASA. Lewis Research Center/IFMD inlet duct and nozzle high speed validation experiments (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Personnel from NASA Lewis Research Center spoke on the subject of inlet duct and nozzle high speed validation experiments to include crossing shocks and boundary layer interaction, unsteady shock/boundary layer interactions, and vortex generators. Attention was also paid to the subjects of high speed mixing and transition ducts. Specific application was made to the NASP hypermixing concepts.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 2nd NASA CFD Validation Workshop; p 197-231
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Summary of NASA. Lewis Research Center validation efforts (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: NASA Lewis Research Center personnel presented a summary of LeRC validation experiments. The subjects discussed included: iced wing, linear transonic cascade, transition duct aerodynamics, transition duct heat transfer, low speed centrifugal compressor, turbomachinery blade row interactions, and three dimensional fluid mechanics.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 2nd NASA CFD Validation Workshop; p 100-125
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    NASA. Langley Research Center CFD code validation program overview (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: A presentation by Langley Research Center covered subjects of: LaRC approach to CFD code validation, experimental CFD perceptions, CFD code validation program experiment, and highlights of the experiment. The objective of the validation program and the approach taken are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, 2nd NASA CFD Validation Workshop; p 1-21
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    NASA low speed centrifugal compressor (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: The flow characteristics of a low speed centrifugal compressor were examined at NASA Lewis Research Center to improve understanding of the flow in centrifugal compressors, to provide models of various flow phenomena, and to acquire benchmark data for three dimensional viscous flow code validation. The paper describes the objectives, test facilities' instrumentation, and experiment preliminary comparisons.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 2nd NASA CFD Validation Workshop; p 232-256
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Flow over a rearward facing step (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: The characteristics of flow over a rearward facing step is discussed in a paper presented by NASA Lewis Research Center personnel. The objective is to obtain data which will be used for validation of Direct Numerical Simulations being developed at NASA Langley and Ames. Two phases of the work are identified as a study of large scale structures in the flow using hot-wire/cold wire techniques and the development of a statistical data base for using three-component laser velocimetry.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, 2nd NASA CFD Validation Workshop; p 182-196
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Overview of CFD flow modeling and validation: NASA. Ames Research Center (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: NASA Ames Center personnel presented data on stages of code development and corresponding experiments in the application of computational fluid dynamics for aeronautical investigations. Specific subjects included algorithms, grid generation, facilities, instrumentation, and data acquisition. Numerical simulation and flow modelling were described to show the procedure for calibration and validation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, 2nd NASA CFD Validation Workshop; p 45-69
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    Status of NASA. Marshall Space Flight Center CFD application and validation activities (1990)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: NASA Marshall Space Flight Center personnel presented a paper on the status of MSFC computational fluid dynamics application and validation activities. Subjects discussed included the Space Shuttle Main Engine studies, unsteady multistage turbine loads, fuel pump discharge volutes, and injector LOX inlet results based on fundamental flows, subcomponents, and interactive components/systems.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, 2nd NASA CFD Validation Workshop; p 70-99
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Fluid management in the optimization of space construction (1990)
    In:  CASI
    Details
    Publication Date: 2004-10-02
    Description: Fluid management impacts strongly on the optimization of space construction. Large quantities of liquids are needed for propellants and life support. The mass of propellant liquids is comparable to that required for the structures. There may be a strong dynamic interaction between the stored liquids and the space structure unless the design minimizes the interaction. The constraints of cost and time required optimization of the supply/resupply strategy. The proper selection and design of the fluid management methods for: slosh control; stratification control; acquisition; transfer; gauging; venting; dumping; contamination control; selection of tank configuration and size; the storage state and the control system can improve the entire system performance substantially. Our effort consists of building mathematical/computer models of the various fluid management methods and testing them against the available experimental data. The results of the models are used as inputs to the system operations studies. During the past year, the emphasis has been on modeling: the transfer of cryogens; sloshing and the storage configuration. The work has been intermeshed with ongoing NASA design and development studies to leverage the funds provided by the Center.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Second Annual Symposium; p 412-433
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Application of the Semivariogram Textural Classifier (STC) to SIR-B data of Borneo (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: This paper presents the results of an application of the semivariogram textural classifier to SIR-B data. Ford and Casey (1988) performed a visual interpretation of a SIR-B image of a tropical rain forest in Borneo in which they recognized and mapped three units of forest canopy (coastal lowland forest, tidal forest and swamp) and two units of open areas (clearcut and wetland). In this study the same image is classified using the STC in an attempt to emulate their interpretation.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 53-57
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    River and lake ice conditions as determined from AIRSAR imagery (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: Synthetic aperture radar (SAR) imagery data can provide information on types and distribution of river and lake ice needed for studying river ice processes and dynamics, monitoring ice during winter navigation, and formulating ice control strategies. Visible and IR remote sensing systems cannot provide such data and present field methods are inadequate for characterizing ice conditions over long river reaches. Our ongoing analysis of JPL's AIRSAR imagery data and concurrent ground truth of ice conditions on the Tanana River and surrounding lakes near Fairbanks, Alaska, in March 1988, has resulted in several findings: hummocked ice covers and zones of variable ice surface roughness within them can be differentiated; C- and L-band data are more sensitive than P-band to the range of surface roughnesses encountered; smooth, level ice that is clear or contains small bubbles produces little backscatter; snow-covered river ice, whether rough or smooth, is distinguishable from snow-covered river sediments on exposed river beds and unvegetated bars; and open water leads are readily distinguished.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 37-42
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    Preliminary results from the MAESTRO 1 Campaign over the Black Forest (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: The Joint Research Center (JRC) Ispra and the European Space Agency (ESA) have co-sponsored the deployment of the National Aeronautics and Space Agency (NASA) and Jet Propulsion Laboratory (JPL), C-, L-, and P-band polarimetric synthetic aperture radar (SAR) in Europe in mid-August 1989. This deployment represents the first opportunity for European agencies and institutes to evaluate the current state of the art of multifrequency polarimetric imaging technology over European Test Sites. Of particular interest to the Joint Research Center (JRC) Ispra is the Black Forest Test Site at Freiburg in the Federal Republic of Germany. This Test Site incorporates the Villingen region of the Black Forest to the south-west of Germany. This paper reports upon the activities undertaken in preparation for the MAESTRO 1 Campaign in the Black Forest Test Site. In particular this paper reports upon the ground data collection campaign for the Freiburg Test Site where extensive and intensive ground data measurements were undertaken. These measurements were based upon standard ground data collection protocols developed for forestry by the JRC and utilized throughout Europe for the MAESTRO 1 Campaign. The paper then goes on to present preliminary results derived from the SAR data using the JRC-developed software for polarimetric data interpretation, POLTOOL.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 43-52
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    Comparison of active and passive microwave signatures of Arctic sea ice (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: In March 1988, overlapping active and passive microwave instrument data were acquired over Arctic sea ice using the NASA DC-8 aircraft equipped with multifrequency, variable polarization SAR and radiometer. Flights were conducted as a series of coordinated underflights of the DMSP SSM/I satellite radiometer in order to validate ice products derived from the SSM/I radiances. Subsequent flights by an NRL P-3 aircraft enabled overlapping high-resolution, single frequency image data to be acquired over the same regions using a Ka-band scanning microwave radiometer. In this paper, techniques are discussed for the accurate coregistration of the three aircraft datasets. Precise coregistration to an accuracy of 100 m plus or minus 25 m has, for the first time, enabled the detailed comparison of temporally and spatially coincident active and passive airborne microwave datasets. Preliminary results from the intercomparisons indicate that the SAR has highly frequency- and polarization-dependent signatures, which at 5.3 GHz (C-band) show an extremely high correlation with the 37 GHz radiometric temperatures.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 29-36
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    Synthetic aperture radar observations of the Greenland ice sheet (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: Results of preliminary analyses of aircraft polarimetric SAR data acquired over the Greenland Ice Sheet are presented. Data were collected in August 1989 by the Jet Propulsion Laboratory (JPL) multifrequency, polarimetric SAR using the NASA DC-8 aircraft over southern Greenland. Data of this kind are the first to be acquired over an ice sheet. They are complementary to the limited coverage provided by the SEASAT satellite SAR in 1978, and more recent aircraft X-band SAR image coverage. Frequency and polarization dependencies observed in the P-, L-, and C-band image products are attributed to large-scale variations in the snow and ice surface characteristics. At this time of year, during the ablation season, ice topography exerts a strong influence upon drainage and other hydrological features on the ice sheet surface. Systematic trends in backscatter strength observed across regions of changing snow facies are suggestive of a capability to map areas of snow wetness. Trends observed at C-band indicate that algorithms could possibly be developed which have the ability to delineate areas of significant melt.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 21-28
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Ground truth measurement for the analysis of airborne SAR data recorded over Oberpfaffenhofen, FRG, 1989 (1990)
    In:  CASI
    Details
    Publication Date: 2005-08-04
    Description: As a preliminary investigation to the joint multiparameter SIR-C/X-SAR shuttle experiment of NASA/JPL (USA), DLR (FRG), and PSN (Italy) which is scheduled for the year 1992 an airborne SAR campaign was conducted over Oberpfaffenhofen, FRG, in August 1989. Primarily this campaign was planned to test and verify equipment and algorithms developed at the DLR to calibrate multifrequency polarimetric SAR data. Oberpfaffenhofen is designated as one of the super test sites for the SIR-C/X-SAR experiment which will be imaged under all circumstances except severe mission errors. A super test site drives radar parameters and look directions and the recorded SAR data will be calibrated. In addition ancillary data will be available for the site. During the airborne STAR campaign conducted in the week of August 14th 1989 various sensor types were used to record remote sensing data over the calibration test site and its vicinity: the polarimetric DC-8 JPL-SAR (P-, L-, C-band), the DLR airborne SAR (C-, X-band), color infrared aerial photography (DLR), and the truck-mounted scatterometer (C- and X-band) of the Institute for Navigation, University of Stuttgart (INS). Because of this variety of different sensor types used and out of the fact that sufficiently large forested and agriculturally used areas were planned to be covered by these sensors, the interest of several German research groups involved in investigations concerning SAR land applications arose. The following groups carried out different ground-truth measurements: University of Bonn, Institute for plant cultivation (plant morphology and moisture content); University of Braunschweig, Institute for Geography (soil moisture and surface roughness); University of Freiburg, Institute for Geography (dielectric soil properties, landuse); and University of Munich, Institute for Geography (landuse inventory, plant, surface, and soil parameters). This paper presents the joint ground truth activities of the Institute for Geography, University of Munich, and the German Remote Sensing Data Center of the DLR.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: JPL, Proceedings of the Second Airborne Synthetic Aperture Radar (AIRSAR) Workshop; p 8-13
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Unstructured finite element mesh generation and adaptive procedures for CFD (1990)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: A method is described for generating unstructured meshes of triangles or tetrahedra for computational domains of complex geometrical shape. To illustrate the power of the approach, it is applied to the solution of flows past several complete aircraft configurations. The advocated approach allows for the natural incorporation of mesh adaptivity and this is demonstrated for both inviscid and viscous computations in two and three dimensions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD, Applications of Mesh Generation to Complex 3-D Configurations; 12 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    Applications of algebraic grid generation (1990)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: Techniques and applications of algebraic grid generation are described. The techniques are univariate interpolations and transfinite assemblies of univariate interpolations. Because algebraic grid generation is computationally efficient, the use of interactive graphics in conjunction with the techniques is advocated. A flexible approach, which works extremely well in an interactive environment, called the control point form of algebraic grid generation is described. The applications discussed are three-dimensional grids constructed about airplane and submarine configurations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD, Applications of Mesh Generation to Complex 3-D Configurations; 12 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    A defect stream function formulation for compressible turbulent boundary layers (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Progress to date on the development of a method for turbulent, wall-bounded flow which uses the defect stream function formulation in the outer layer and an analytic law of the wall and wake formulation in the inner region is reviewed. This two-formulation approach avoids the need to computationally resolve the high-gradient inner layer. One of the most appealing recent developments is the transformation of the compressible governing equation for the defect stream function into a linear, second-order differential equation which has analytic solutions for many problems of practical interest. Numerical and analytic results for incompressible and compressible flows are shown to be in excellent agreement with experimental results. In this paper the two-formulation approach is applied to primitive-variable computations. Excellent comparisons with experiment are presented for two compressible flat plate flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    Remote sensing of Italian volcanos (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The results of a July 1986 remote sensing campaign of Italian volcanoes are reviewed. The equipment and techniques used to acquire the data are described and the results obtained for Campi Flegrei and Mount Etna are reviewed and evaluated for their usefulness for the study of active and recently active volcanoes.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: EOS (ISSN 0096-3941); 71; 1789-179
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    Mars Observer's global mapping mission (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The objectives of the Mars Observer global mapping mission are to determine the global elemental and mineralogical character of the Martian surface material, define globally the topography and gravitational field of Mars, establish the nature of Mars's magnetic field, determine the time and space distribution, abundance, sources, and sinks of volatile Martian material and dust over a seasonal cycle, and explore the structure and aspects of the circulation of the Martian atmosphere. The experiments and instruments to be used in this mission are described, and the operations and data analysis are briefly considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: EOS (ISSN 0096-3941); 71; 1099
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    Quasi-coherent structures in the turbulent boundary layer. II - Verification and new information from a numerically simulated flat-plate layer (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    Velocity and pressure fields associated with near-wall turbulence structures (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Computer generated databases containing velocity and pressure fields in three-dimensional space at a sequence of time-steps, were used for the investigation of near-wall turbulence structures, their space-time evolution, and their associated pressure fields. The main body of the results were obtained from simulation data for turbulent channel flow at a Reynolds number of 180 (based on half-channel height and friction velocity) with a grid of 128 x 129 x and 128 points. The flow was followed over a total time of 141 viscous time units. Spanwise centering of the detected structures was found to be essential in order to obtain a correct magnitude of the associated Reynolds stress contribution. A positive wall-pressure peak is found immediately beneath the center of the structure. The maximum amplitude of the pressure pattern was, however, found in the buffer region at the center of the shear-layer. It was also found that these flow structures often reach a maximum strength in connection with an asymmetric spanwise motion, which motivated the construction of a conditional sampling scheme that preserved this asymmetry.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    Quasi-coherent structures in the turbulent boundary layer. I - Status report on a community-wide summary of the data (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A review is presented of the approach, motivation and early results of a reevaluation of the knowledge collected by the research community during thirty years of research on the structure of turbulent boundary layers. Four distinctions or criteria concerning the need to improve the practices in this field are discussed: data versus inferences, possible versus actual versus significant events, one structure versus many, and one or two flows versus the totality of data. Attention given to the known quasi-coherent structures show that three factors significantly reduce the information available from laboratory data as a basis for forming a complete model of the quasi-coherent structure in the turbulent boundary layer: (1) the necessity to ensemble average probe output with resulting loss of phase information, (2) the inability to see more than one or two of the various types of structures simultaneously, and (3) the inability to see the spatial relations between the various quasi-coherent structures resulting from (1) and (2).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Statistical analysis of near-wall structures in turbulent channel flow (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The two-point correlation tensor is used to analyze near-wall structures in turbulent channel flow. Simulation results have been utilized to obtain the correlation tensor with sufficient spatial resolution to permit accurate differentiation for computing the vorticity correlation, and the resolution of sharp features such as the shear layer and its corresponding region of spanwise vorticity. Proper orthogonal decomposition and stochastic estimation were observed to yield similar results when appropriate conditions were employed for the estimation. Resulting structures were such that they would be detected by standard conditional sampling methods. The results of decomposing the vorticity field and the velocity field were significantly different, indicating that if a coherent structure is found that dominates the velocity fields, the curl of that velocity structure will not dominate the vorticity field.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    Similarity of organized structures in turbulent shear flows (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Recent analysis of databases generated by direct numerical simulations of homogeneous turbulent shear flows have revealed the presence of coherent structures similar to those in turbulent boundary layers. In this paper these findings and tentative conclusions on their significance are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    Small-scale plasma, magnetic, and neutral density fluctuations in the nightside Venus atmosphere (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The evolution of the Venus small-scale waves as they propagate into the nightsite is examined, and the small-scale structures are compared with the waves in the three components of the magnetic field, magnetic dip angle, and neutral density. It is demonstrated that the small-scale fluctuations evolve between the transterminator and antisolar regions. It is shown that atmospheric gravity waves may also be producing some of the fluctuations observed at longer wavelengths. The electron temperature and density are shown to be approximately 180 deg out of phase and exhibiting the highest correlation of any pair of variables. Waves in the electron and neutral densities are found to be correlated moderately on most orbits, while the average electron temperature is higher when the average magnetic field is more horizontal.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 4085-410
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    Application of remote sensing in tropical forests (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Cloud cover in tropical humid forests can pose serious operational constraints on Landsat TM and SPOT HRV instrumentation, given their respective orbital frequencies of 16 and 26 days. SAR data intrinsically precludes such problems; the increase of data acquisition frequency to daily rates, as with the NOAA AVHRR instrument, also bears consideration. It is deemed essential that SAR data-related research be expedited, in order to ascertain inherent SAR information for tropical forests in a timely and cost-effective manner.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    A sensor fusion field experiment in forest ecosystem dynamics (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The background of the Forest Ecosystem Dynamics field campaign is presented, a progress report on the analysis of the collected data and related modeling activities is provided, and plans for future experiments at different points in the phenological cycle are outlined. The ecological overview of the study site is presented, and attention is focused on forest stands, needles, and atmospheric measurements. Sensor deployment and thermal and microwave observations are discussed, along with two examples of the optical radiation measurements obtained during the experiment in support of radiative transfer modeling. Future activities pertaining to an archival system, synthetic aperture radar, carbon acquisition modeling, and upcoming field experiments are considered.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Experiment design and operations (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The objectives, design, and field operations of the First ISLSCP Field Experiment (FIFE) are described. The simultaneous acquisition of satellite, atmosphere, and surface data, and the understanding of the processes governing surface energy and mass exchange and how these are manifested in satellite-resolution radiometric data are identified as the specific objectives of the field-phase experiment. The central issues concerning the design of the field experiment are considered: the size of the site, the duration of the experiment, and the location of the site; it is noted that the Konza Prairie National Reserve was selected as the focus of the study. Field operations in 1987 and 1989 are discussed, and it is pointed out that a data set is available now from a single combined repository to all FIFE investigators, and that scientists can test models and algorithms on scales consistent with satellite observations and with enough supporting data on finer scales.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    Functional relation among subpixel canopy cover, ground shadow, and illuminated ground at large sampling scales (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The functional relation among subpixel canopy cover, illuminated soil, and shadowed soil, which progressively develops with increasing pixel size, is investigated for Poisson distributed plants using a geometric canopy simulation model. An analytical relation among cover components is shown to be applicable when the scale of the pixel is much larger than the scale of the plant and ground shadow. The analysis is facilitated through the use of a nondimensional solar-geometric similarity parameter, eta, equal to the ratio of the area of one plant canopy to its associated ground shadow area, as viewed from nadir. A sampling scale ratio, defined as the ratio of the area of the pixel to the mean area of a single plant shadow, is tested as a quantitative criterion to evaluate when the functional relation among subpixel components occurs. The results of a remote sensing experiment over a natural conifer landscape provide preliminary confirmation of the theoretical analysis.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    Progress in microwave remote sensing of soil moisture (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Significant progress has been made in the application of microwave remote sensing for measuring soil moisture. Both passive and active systems have demonstrated the capability for measuring soil moisture. However, several questions are still unresolved regarding the optimal instrument configuration and other target characteristics, such as roughness and vegetation. In addition, the most likely disciplines for using these data, agriculture and hydrology, do not currently possess adequate models or procedures for using these new data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Canadian Journal of Remote Sensing (ISSN 0008-2821); 16; 6-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Comment on 'Update on terrestrial ages of Antarctic meteorites' by K. Nishiizumi, D. Elmore and P. W. Kubik (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 99; 4, Se; 380-382;
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Unsteady viscous flow around a circular cylinder found by the hopscotch scheme on a vector processing machine (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The hopscotch scheme is examined to see whether it can compete effectively with implicit schemes for the integration of the Navier-Stokes equations on a vector processing machine. This scheme is stable as long as the Courant number is less than or equal to one and it does not underestimate viscous effects. The accuracy of the scheme is tested on one- and two-dimensional problems whose exact solutions are known. The scheme is then used to simulate flows around a circular cylinder with Reynolds numbers 200, 500 and 1000.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Applied Numerical Mathematics (ISSN 0168-9274); 6; 195-208
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    Geochemistry and genesis of the angrites (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The major and trace elements were analyzed in samples of LEW86010, LEW87051, and Angra dos Reis angrites were analyzed using INAA and fused-bead EMP techniques. Results suggest that all three angrites originated on a volatile-depleted (Na-poor) but oxidized parent body or on several bodies. The combination of low Na and high FeO/MnO found in these samples suggests that the extreme Na depletion was caused by parent-body outgassing during differentiation, rather than by nebular processes. It was also found that the refractory-element abundances observed in LEW86010 and LEW87051 are related via olivine control; it is suggested that LEW86010 may be a residual melt from a LEW87051-like precursor or that LEW87051 formed from a LEW86010-like precursor via olivine accumulation. On the other hand, the Angra dos Reis displayed an unusual refractory element pattern suggesting that either the angrite parent body was heterogeneous or that Angra dos Reis was formed on a parent body different from that of the other two angrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 3209-321
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    Relationship of multispectral satellite data to land surface evaporation from the Australian continent (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Based on NOAA-9 AVHRR and Nimbus-7 SMMR satellite data, satellite indices of vegetation from the Australian continent are calculated for the period of May 1986 to April 1987. Visible (VIS) and near infrared (NIR) reflectances and the normalized difference (ND) vegetation index are calculated from the AVHRR sensor. The microwave polarization difference (PD) is also calculated as the difference between the vertically and horizontally polarized brightness temperatures at 37 GHz. ND, PD, VIS, and NIR indices were plotted against rainfall and water balance estimates of evaporation. It is concluded that direct satellite monitoring of annual evaporation across the Australian continent using PD or VIS satellite indices of vegetation biomass appears possible for areas with evaporation less than 600 mm/y and that use of the ND relationship at continental scale may underpredict monthly evaporation of forests relative to agriculture.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 11; 2069-208
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    Zonal motion and structure in Jupiter's upper troposphere from Voyager infrared and imaging observations (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Global digital maps of Jupiter's upper-tropospheric temperature have been generated at the 270- and 150-mb pressure levels, together with IR cloud optical depths at 5 and 45 microns and the ammonia abundance near the 680-mb pressure level, on the basis of Voyager IRIS north-south mapping sequences. Attention is given to the 270-mb and 45 micron data; global digital maps are presented for violet and orange reflectivities. The dominant upper tropospheric thermal structures move at a rate far different from that of the cloud indicators, and are noted to remain stationary relative to the planet's bulk rotation. Strong stationary features are found at a zonal wavenumber of 9 near 15 deg N latitude and of 11 near 20 deg latitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 88; 39-72
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Tidal disruption of solid bodies (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The problem of stress, strain, and breakup in solid satellites and stray bodies subject to tidal perturbations is presently addressed in view of three novel considerations. After presenting a new analytic solution for the stress tensor in a homogeneous and compressible elastic sphere, where the inclusion of compressibility alters stresses by several percent, realistic failure criteria are noted to demonstrate the general failure of such ductile bodies as iron meteoroids by plastic shear, while brittle ice bodies fail by either tensile or shear fracture. A reexamination of crack propagation after initial failure allows the diverse breakup criteria to be reconciled.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 88; 24-38
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    Interfacial dynamics of two liquids under an oscillating gravitational field (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The evolution of two miscible liquids meeting at an initially sharp interface inside a cavity under microgravity g-jitter conditions is studied numerically. The response of the interface and kinematics of the flowfield to various g-jitter accelerations and aspect ratio variations is shown. The interface region acts like a vortex source sheet, and it can be unstable to Kelvin-Helmholtz and Rayleigh-Taylor instabilities. The vortices produced along the interface can serve as a stirring mechanism to promote local mixing. Below the critical Stokes-Reynolds number, the destabilization of the interface results in deformation into wavy structures. In some parameter regions, these structures oscillate in time; in others, they are quasi-steady. Above the critical Stokes-Reynolds number, 'chaotic' instability results, and the interface breaks into concentration pockets. The morphology of the initial breakup is similar to observed Rayleigh-Taylor instability. Subsequent mixing of the two fluids after the breakup of the interface is then very rapid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 28; 1933-194
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    Low-frequency scattering from cylindrical structures at oblique incidence (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Classical Rayleigh scattering theory is extended to the case of a homogeneous dielectric cylinder of arbitrary cross section whose transverse dimensions are much smaller than the wavelength. By assuming that the surface fields can be approximated by those of the infinite cylinder, the far zone scattered field is expressed in terms of polarizability tensors, whose properties are discussed. Numerical results are presented for circular, semicircular, triangular, and square cylinders. The results are applicable to the remote sensing of twigs, stalks, and vegetation needles at centimeter and millimeter wavelengths.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 28; 879-885
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    Stability of an oscillated fluid with a uniform density gradient (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Instabilities in a fluid with a constant density gradient that is subject to arbitrarily oriented oscillatory accelerations are considered. With the Boussinesq approximation and for the case of an unbounded fluid, transformation to Lagrangian coordinates allows the reduction of the problem to an ordinary differential equation for each three-dimensional wavenumber. The problem has three parameters: the nondimensional amplitude R of the base-state oscillation, the nondimensional level of background steady acceleration, which for some cases can be represented in terms of a local (in time) Richardson number Ri, and the Prandtl number Pr. Some general bounds on stability are derived. For Pr = 1 closed-form solutions are found for impulse (delta function) accelerations and a general asymptotic solution is constructed for large R and general imposed accelerations. The asymptotic solution takes advantage of the fact that at large R wave growth is concentrated at 'zero points'. These are times when the effective vertical wavenumber passes through zero. Kelvin-Helmholtz instabilities are found to dominate at low R, while Rayleigh-Taylor instabilities dominate at high R. At high R, the uniform shear of the Kelvin-Helmholtz case tends to distort and weaken instability waves. With unsteady flows, Ri = 1/4 is no longer an instability limit. Significant instabilities have been found for sinusoidal forcing for Ri up to 0.6.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 219; 449-468
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    Cloud-tracked winds from Pioneer Venus OCPP images (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented on the analysis of the Pioneer Venus Orbiter Cloud Photopolarimeter (OCPP) UV images, covering 80-day periods from 1979 to 1985. The analysis provides a method for determining wind speeds at the cloud level, from the motions of cloud UV features. Data used for tracking the cloud feature motions are described along with the analysis method. The results identified four wave modes: a diurnal solar tide, a semidiurnal solar tide, a '4-day equatorial' wave, and a '5-day midlatitude' wave. The features of these wave modes are described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 47; 2053-208
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    (Ar-39)-(Ar-40) dating of mesosiderites - Evidence for major parent body disruption less than 4 Ga ago (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The (Ar-39) (Ar-40) chronologies were determined for 14 different mesosiderites representing the full range of classification according to recrystallization, and these chronologies were compared with analogous data for other meteorite types and for lunar highland rocks. Results of Ar-Ar chronologies indicate the history of a degassing of Ar due to a major thermal event that occurred less than 3.9 Ga ago; this event is not the metal-silicate mixing event, which is known to have occurred earlier than 4.4 Ga ago. It is suggested that a major collisional disruption-reassembly event less than 3.9 Ga ago took place, leaving the metal-silicate breccias buried under tens of kilometers of rubble, where they cooled slowly through the Ar closure temperatures.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 2549-256
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    Inter- and intra-group compositional variations in Apollo 15 pyroclastic green glass - An electron- and ion-microprobe study (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented on major- and trace-element abundance analyses of Apollo 15 pyroclastic green glasses from groups A, B, C, D, and E, carried out using electron- and ion-microprobe techniques. The diagrams depicting Sr, Zr, Ba, and Nd vs Co variations indicate the presence of a high-Co trend in groups A and D and a low-Co trend in groups B and C. Group-E glasses were found to be significantly enriched in Sr, relative to the other four glass groups. Chemical data of this study were integrated with previous data to evaluate various magmatic processes that have been proposed in the past to explain chemical variations in the lunar green glass. Results of calculations using a source mixing model suggest that the Apollo 15 green glasses represent multiple eruptive events from three chemically distinct but compositionally variable source regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 54; 2565-257
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Riblets (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In addition to characterizing the various concepts reported in the literature on longitudinally-ribbed surface for aerodynamic surface drag reduction, the present development status evaluation of this technology correlates all available experimental data. An analysis of these data is then conducted to ascertain the parameters most directly involved in drag reduction, and to evaluate the effects which have thus far been exerted on turbulent boundary layer structures. Such advanced riblet techniques as compound and three-dimensional riblets, riblets in combination with large-eddy breakup devices, and riblets with suction/blowing, are also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    Active wave control of boundary-layer transition (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The physical processes involved in the boundary layer instability-generation and transition process seem to pose basic restrictions on the implementation of active, wave-based transition-control methods. While suppression short of elimination is possible by these means for primary disturbances, wave-interaction instabilities demand that the control be implemented almost immediately after the appearance of primary disturbances; even slight delays can negate the intended beneficial effects, and this basic problem is exacerbated at the higher Reynolds numbers typical of aircraft in cruising flight. Three-dimensional disturbances are noted to be important in this context, together with the continuous regeneration of TS waves.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Energy sources for Triton's geyser-like plumes (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Four geyser-like plumes were discovered near Triton's south pole in areas now in permanent sunlight. Because Triton's southern hemisphere is nearing a maximum summer solstice, insolation as a driver or a trigger for Triton's geyser-like plumes is an attractive hypothesis. Trapping of solar radiation in a translucent, low-conductivity surface layer (in a solid-state greenhouse), which is subsequently released in the form of latent heat of sublimation, could provide the required energy. Both the classical solid-state greenhouse consisting of exponentially absorbed insolation in a gray, translucent layer of solid nitrogen, and the 'super' greenhouse consisting of a relatively transparent solid-nitrogen layer over an opaque, absorbing layer are plausible candidates. Geothermal heat may also play a part if assisted by the added energy input of seasonal cycles of insolation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 431-435
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    Temperature and thermal emissivity of the surface of Neptune's satellite Triton (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Analysis of the preliminary results from the Voyager mission to the Neptune system has provided the scientific community with several methods by which the temperature of Neptune's satellite Triton may be determined. If the 37.5 K surface temperature reported by several Voyager investigations is correct, then the photometry reported by the imaging experiment on Voyager requires that Triton's surface have a remarkably low emissivity. Such a low emissivity is not required in order to explain the photometry from the photopolarimeter experiment on Voyager. A low emissivity would be inconsistent with Triton having a rough surface at the about 100-micron scale as might be expected given the active renewal processes which appear to dominate Triton's surface.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 429-431
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    Subsurface energy storage and transport for solar-powered geysers on Triton (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The location of active geyser-like eruptions and related features close to the current subsolar latitude on Triton suggests a solar energy source for these phenomena. Solid-state greenhouse calculations have shown that sunlight can generate substantially elevated subsurface temperatures. A variety of models for the storage of solar energy in a subgreenhouse layer and for the supply of gas and energy to a geyser are examined. 'Leaky greenhouse' models with only vertical gas transport are inconsistent with the observed upper limit on geyser radius of about 1.5 km. However, lateral transport of energy by gas flow in a porous N2 layer with a block size on the order of a meter can supply the required amount of gas to a source region about 1 km in radius. The decline of gas output to steady state may occur over a period comparable with the inferred active geyser lifetime of 5 earth years. The required subsurface permeability may be maintained by thermal fracturing of the residual N2 polar cap. A lower limit on geyser source radius of about 50 to 100 m predicted by a theory of negatively buoyant jets is not readily attained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 424-429
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    Triton's geyser-like plumes - Discovery and basic characterization (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: One model for the mechanism driving the plumes of the four active geyser-like eruptions observed by Voyager 2 on Triton is a heating up of nitrogen ice in a subsurface greenhouse environment, where nitrogen gas pressurized by solar heating explosively vents to the surface carrying clouds of ice and dark particles into the atmosphere. A temperature increase of less than 4 K above the ambient surface value of 38 + or - 3 K suffices to drive the plumes to 8-km altitude. Each eruption may last a year or more, over the course of which 0.1 cu km of ice is sublimed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 250; 410-415
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    Sensitivity of the normalized difference vegetation index to subpixel canopy cover, soil albedo, and pixel scale (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An analytical framework is provided for examining the physically based behavior of the normalized difference vegetation index (NDVI) in terms of the variability in bulk subpixel landscape components and with respect to variations in pixel scales, within the context of the stochastic-geometric canopy reflectance model. Analysis focuses on regional scale variability in horizontal plant density and soil background reflectance distribution. Modeling is generalized to different plant geometries and solar angles through the use of the nondimensional solar-geometric similarity parameter. Results demonstrate that, for Poisson-distributed plants and for one deterministic distribution, NDVI increases with increasing subpixel fractional canopy amount, decreasing soil background reflectance, and increasing shadows, at least within the limitations of the geometric reflectance model. The NDVI of a pecan orchard and a juniper landscape is presented and discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 32; 169-187
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    Bidirectional measurements of surface reflectance for view angle corrections of oblique imagery (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An apparatus for acquiring bidirectional reflectance-factor data was constructed and used over four surface types. Data sets were obtained over a headed wheat canopy, bare soil having several different roughness conditions, playa (dry lake bed), and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetation indices as related to view and solar zenith angles. The wheat canopy exhibited the largest BRF changes with view angle. BRFs for the red and the NIR bands measured over wheat did not have the same relationship with view angle. NIR/Red ratios calculated from nadir BRFs changed by nearly a factor of 2 when the solar zenith angle changed from 20 to 50 degs. BRF versus view angle relationships were similar for soils having smooth and intermediate rough surfaces but were considerably different for the roughest surface. Nadir BRF versus solar-zenith angle relationships were distinctly different for the three soil roughness levels. Of the various surfaces, BRFs for gypsum sand changed the least with view angle (10 percent at 30 degs).
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment (ISSN 0034-4257); 32; 189-202
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    Light polarization by vegetation cover - Possible agricultural applications (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A review of the physical mechanisms involved in light polarization by reflecting surfaces is presented and experimental results for single leaf, bare soil, and plant canopies are analyzed. It is shown that light polarization can be employed to identify different plant canopies and to estimate their standing biomass. For bare soils, light polarization can be used to monitor the surface soil moisture and the state of the surface. Thus light polarization may be considered as a new remote sensing technique for potential agricultural application.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Canadian Journal of Remote Sensing (ISSN 0008-2821); 16; 32-41
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    Magellan orbits Venus (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Various events surrounding Magellan's orbit of Venus are recounted. Significant events include the successful firing of a solid rocket motor while the spacecraft was behind Venus to transfer it from a solar-centered trajectory to an orbit around the planet. The spacecraft orbits Venus every 3.26 hours at a maximum altitude of 8500 km and minimum altitude of 291 km in an elliptical orbit. The successful August 16 test of the synthetic-aperture radar system is discussed, noting that it produced two strips, each about 20 km x 16,000 km, revealing details as small as 120 m. Two anomalies causing a delay in the start of mapping operations and subsequent breaks in the communication link with earth for 14.5 hours and 17.7 hours are discussed. Protective measures directed from the spacecraft's ROM during breach of contact are listed, and possible causes of the anomalies are suggested, such as solar activity or hardware or software elements, although the actual cause is not yet known.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Spaceflight (ISSN 0038-6340); 32; 334-337
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    Comparative dynamics of the ionospheres of Venus and Mars at large solar zenith angles (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Simple three-ion spectral models of the dynamics and ion chemistry in the upper ionospheres of Venus and Mars have been constructed by including two minor ions, H(+) and O2(+) for Venus and O(+) and CO2(+) for Mars, along with the major ion, O(+) for Venus and O2(+) for Mars. Horizontal flow velocities and ion densities have been calculated in each case and compared with available measured data. For Venus, the present calculations yield results in agreement with earlier finite-difference model studies and with experimental observations. Calculations for Mars are in agreement with the limited observational data obtained by the Viking landers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Indian Journal of Radio and Space Physics (ISSN 0367-8393); 19; 88-102
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    Albedo and color maps of the Saturnian satellites (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 87; 339-357
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Cosmogenic nuclides in extraterrestrial materials (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Research on cosmogenic nuclides in extraterrestrial materials is summarized. Methods for determining average production rates in meteorites are considered as well as the composition dependence of production rates. Also discussed are lunar meteorites, solar-gas-rich meteorites, presolar grains, and solar cosmic rays.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Reviews of Geophysics (ISSN 8755-1209); 28; 253-275
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    Recent advances, trends and new perspectives via enthalpy-based finite element formulations for applications to solidification problems (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The present paper describes recent advances and trends in finite element developments and applications for solidification problems. In particular, in comparison to traditional methods of approach, new enthalpy-based architectures based on a generalized trapezoidal family of representations are presented which provide different perspectives, physical interpretation and solution architectures for effective numerical simulation of phase change processes encountered in solidification problems. Various numerical test models are presented and the results support the proposition for employing such formulations for general phase change applications.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 30; 803-820
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    Remote sensing of tropical forests - An overview of research and applications using non-photographic sensors (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A comprehensive overview is presented on how remote sensing technology has been applied to tropical forest monitoring over the past 20 years. Research needs for monitoring the condition and extent of tropical forests are suggested. The discussion focuses on nonphotographic sensors, especially those on orbiting satellites. Several remote sensing approaches to tropical forest monitoring are outlined, including NOAA AVHRR, Landsat MSS, the Landsat Thematic Mapper, SPOT-1, and Synthetic Aperture Radar. Suggested research needs are addressed, along with discussions on the use of Geographic Information Systems, and multistage and multisensor approaches in data analysis and acquisition. It is concluded that additional research and technique development is urgently needed to advance the utility of remotely sensed data for tropical forest monitoring. However, there is sufficient information available now to prototype a global tropical forest monitoring system that would utilize current satellite sensors complemented with airborne sensors for detailed measurements on sample locations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 56; 1343-135
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    Inviscid flux-splitting algorithms for real gases with non-equilibrium chemistry (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Formulations of inviscid flux splitting algorithms for chemical nonequilibrium gases are presented. A chemical system for air dissociation and recombination is described. Numerical results for one-dimensional shock tube and nozzle flows of air in chemical nonequilibrium are examined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 90; 371-395
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Normalization of satellite imagery (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Sets of Thematic Mapper (TM) imagery taken over the Washington, DC metropolitan area during the months of November, March and May were converted into a form of ground reflectance imagery. This conversion was accomplished by adjusting the incident sunlight and view angles and by applying a pixel-by-pixel correction for atmospheric effects. Seasonal color changes of the area can be better observed when such normalization is applied to space imagery taken in time series. In normalized imagery, the grey scale depicts variations in surface reflectance and tonal signature of multi-band color imagery can be directly interpreted for quantitative information of the target.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 11; 1331-134
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    A model of Saturn's magnetic field based on all available data (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A model of Saturn's magnetic field, called Saturn Pioneer Voyager (SPV), is developed on the basis of an analysis of three sets of data: those from the Pioneer 11, the Voyager 1, and the Voyager 2 magnetometers. It is shown that the SPV model fits the data observed between 1.3 and 8.0 Saturn radii from the planet's center with a 1.13 percent weighted rms average of the percent differences between the observed and modeled fields, which is substantially better than the fits yielded by any of the previous models.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 15257-15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Ternary baroeffect with a nondiffusing component (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A systematic analysis is developed which describes the isothermal counterdiffusion of two gases in the presence of a third nondiffusing gas. Four distinct regimes are identified for diffusive slip. The nondiffusing gas reduces the pressure drop in all cases, whether it raises or lowers the mean density. The gas leads to nonzero diffusive slip even in the limit of very disparate masses for the diffusing gases. The implications of these findings for controlling concentration creep in crystal growth are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review Letters (ISSN 0031-9007); 65; 1587-159
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    Backscattering from frost on icy satellites in the outer solar system (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 347; 162-164
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Ubiquitous interstellar diamond and SiC in primitive chondrites - Abundances reflect metamorphism (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: It is shown here that interstellar diamond and SiC were incorporated into all groups of chondrite meteorites. Abundances rapidly go to zero with increasing metamorphic grade, suggesting that metamorphic destruction is responsible for the apparent absence of these grains in most chondrites. In unmetamorphosed chondrites, abundances normalized to matrix content are similar for different classes. Diamond samples from chondrites of different classes have remarkably similar noble-gas constants and isotropic compositions, although constituent diamonds may have come from many sources. SiC seems to be more diverse, partly because grains are large enough to measure individually, but average characteristics seem to be similar from meteorite to meteorite. These observations suggest that various classes of chondritic meteorites sample the same solar system-wide reservoir of interstellar grains.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 347; 159-162
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    Regional aeolian dynamics and sand mixing in the Gran Desierto - Evidence from Landsat Thematic Mapper images (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Mesoscale mapping of spatial variations in sand composition of the Gran Desierto (Sonora, Mexico) was carried out on multispectral Landsat TM images of this region, making it possible to examine the dynamic development of sand sheets and dunes. Compositions determined from remote imagery were found to agree well with samples from selected areas. The sand populations delineated were used to describe the sediment source areas, transport paths, and deposition sites. The image analysis revealed important compositional variations aver large areas that were not readily apparent in the field data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 15463-15
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    Vertical distribution of water in the atmosphere of Venus - A simple thermochemical explanation (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Several lines of evidence concerning the vertical abundance profile of water in the atmosphere of Venus lead to strikingly unusual distributions (the water vapor abundance decreases sharply in the immediate vicinity of the surface) or to serious conflicts in the profiles (different IR bands suggest water abundances that are discrepant by a factor of 2.5 to 10). These data sets can be reconciled if (1) water molecules associate with carbon dioxide and sulfur trioxide to make gaseous carbonic acid and sulfuric acid in the lower atmosphere, and (2) the discrepant 0.94-micrometer water measurements are due to gaseous sulfuric acid, requiring it to be a somewhat stronger absorber than water vapor in this wavelength region. A mean total water abundance of 50 + or - 20 parts/million and a near-surface free water vapor abundance of 10 + or - 4 parts/million are derived.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 249; 1273-127
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    Diagonally inverted lower-upper factored implicit multigrid scheme for the three-dimensional Navier-Stokes equations (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 28; 1642-164
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    Assessment of tropical forest stand characteristics with multipolarization SAR data acquired over a mountainous region in Costa Rica (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A digital terrain elevation data set was coregistered with radar data for assessing tropical forest stand characteristics. Both raw and topographically corrected L-band polarimetric radar data acquired over the tropical forests of Costa Rica were analyzed and correlated with field-collected tree parameter data to study the stand characteristics. The results of analyses using 18 out of 81 plots for sites A and B indicated that per-plot bole volume and tree volume are related to SAR data, particularly at site A. The topographically corrected SAR data appear to produce the same findings as those of uncorrected data.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Vancouver, Canada, July 10-14, 1989) IEEE Transactions on Geoscience and Remote Sensing (ISSN 0196-2892); 752-755
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Diurnal patterns of the bi-directional reflectance of fresh-water ice (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: To improve the interpretation of surface cryospheric albedo from satellite sensor data, diurnal measurements of the spectral bidirectional reflectance of a commonly found fresh water ice type were made, from which hemispherical reflectance can be derived. The purpose of this study is to document its clear-sky, bidirectional reflectance characteristics in the visible (650-670 nm) and near-infrared (810-840 nm) region, assess the diurnal nature of the reflectance, and quantify the surface anisotropy. Bidirectional reflectances of the refrozen slush ice measured show a spectral dependence and change significantly with solar zenith angle. Considerable variation occurs at each view angle and among view angles throughout the day. Although diurnal reflectance patterns were similar in both bands, magnitudes varied greatly, being highest in the visible and lowest in the near-infrared region. With the exception of peak saturated (specular) values in the forward scatter direction, bidirectional reflectance was generally highest in the morning when the surface and the illumination were most diffuse in character.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Annals of Glaciology (ISSN 0260-3055); 14; 153-157
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    Variations of Mars gravitational field and rotation due to seasonal CO2 exchange (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: About a quarter of the Martian atmospheric mass is exchanged between the atmosphere and the polar caps in the course of a Martian year: CO2 condenses to form (or add to) the polar caps in winter and sublimes into the atmosphere in summer. This paper studies the effect of this CO2 mass redistribution on Martian rotation and gravitational field. Two mechanisms are examined: (1) the waxing and waning of solid CO2 in the polar caps and (2) the geographical distribution of gaseous CO2 in the atmosphere. In particular, the net peak-to-peak changes in J2 and J3 over a Martian year are both found to be as much as about 6 x 10 to the -9th. A simulation suggests that these changes may be detected by the upcoming Mars Observer under favorable but realistic conditions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14755-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Atmospheric measurements at Mars via gamma ray spectroscopy (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: This paper describes three methods for measuring the Martian atmosphere using gamma ray spectroscopy. One method determines atmospheric thickness based on the energy-dependent differential attenuation of gamma-ray line pairs from a common element. Another makes a direct determination based on measurements of the line flux generated in the atmosphere, requires knowledge of the concentration of the component being used. The third, which makes use of a single line emitted from the surface where its flux can be established. The effects of stratigraphy on the differential attenuation method are studied, and calculations are reported which show that the measurement of atmospheric argon will be a sensitive indicator of the atmospheric fractionation accompanying CO2 precipitation in south polar regions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14695-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    Infrared radiative transfer in the dust-free Martian atmosphere (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Two theoretical radiative transfer methods are used here to derive synthetic spectra of dust-free Martian atmospheres. One is a versatile, accurate, line-by-line model which completely resolves individual absorption lines to produce high-resolution spectra within gas absorption bands. The other is a fast Voigt quasi-random model which produces accurate results for spectral regions as narrow as 1/cm and is fast enough for routine use in broadband transmission calculations. Synthetic transmission and radiance spectra from these models for dust-free conditions in the Martian atmosphere are used to illustrate the radiative effects of each important absorbing gas and to provide a baseline for comparisons with dust atmosphere spectra.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14577-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Thermal emission spectra of Mars (5.4-10.5 microns) - Evidence for sulfates, carbonates, and hydrates (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Spectra of the Martian thermal emission in the 5.4-10.5 micron region are reported. Emission features at 7.8 and 9.7 microns are attributed to surface silicates, and an emission feature at 6.1 micron is attributed to a molecular water component of the surface material. An absorption band at 8.7 micron and a possible one at 9.8 microns is attributed to sulfate or bisulfate anions probably located at a distorted crystalline site, and an absorption band at 6.7 microns is attributed to carbonate or bicarbonate anions located in a distorted crystalline site. Spectral simulations indicate that the sulfate- and carbonate-bearing minerals are contained in the same particles of airborne dust as the dominant silicate minerals, that the dust optical depth is about 0.6 at a reference wavelength of 0.3 micron over the area of the observed spots, and that sulfates and carbonates constitute 10-15 percent and 1-3 percent by volume of the airborne dust, respectively.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14595-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    Origins of Marslike spectral and magnetic properties of a Hawaiian palagonitic soil (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented on spectral, Moessbauer, static magnetic, petrographic, and compositional data for a Hawaiian palagonitic soil from Mauna Kea (HWMK1). It was found that reflectivity spectra of size separates smaller than 20 microns resemble spectra for Martian bright regions, while spectra of larger size separates show characteristics in common with spectra for Martian dark regions. Data on the HWMK1 soil are consistent with the partitioning of iron among the following minerals: olivine, titanomagnetite, hematite, and a superparamagnetic colored ferric oxide. These mineralogies are heterogeneously distributed within the soil with respect to both particle type and soil-particle diameter. The strongly magnetic titanomagnetite is associated with black particles and is responsible for the magnetic nature of the soil, while the colored weakly magnetic superparamagnetic ferric oxide and minor hematite are associated with orange particles.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14427-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Emplacement of lava flow fields - Application of terrestrial studies to Alba Patera, Mars (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The relationships obtained by Kilburn and Lopes (1988, 1990) for their models of lava flow fields were used to calculate the duration of the emplacement, the average discharge rates, and the average velocities of lavas for the Martian volcano Alba Patera, on which two distinct planimetric types of lava flow field were identified. The validity of using terrestrial analogues for investigating the emplacement conditions of the Alba Patera flow fields is examined. It is concluded that, at least for basaltic-basaltic andesitic compositions, the essential conditions of eruption from Alba Patera may have been similar to those currently observed on earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14383-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    Fault propagation folds induced by gravitational failure and slumping of the Central Costa Rica volcanic range - Implications for large terrestrial and Martian volcanic edifices (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Maps are presented that describe the compressional tectonic structures found at the base of the Central Costa Rica volcanic range (CCRVR), which comprise thrust faults and related fault propagation folds, only partly covered by syntectonic and posttectonic volcanoclastic deposits. Evidence is presented that these structures formed by gravitational failure and lumping of the flanks of the volcanic range. It is suggested that similar structures may be found at the toe of the southern flank of Kilauea volcano, Hawaii, and along the perimeter scarp of the Olympus Mons volcano on Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14357-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    Flank tectonics of Martian volcanoes (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The origin of the numerous terraces on the flanks of the Olympus Mons volcano on Mars, seen on space images to be arranged in a roughly concentric pattern, is investigated. The images of the volcano show that the base of each terrace is marked by a modest but abrupt change in slope, suggesting that these terraces could be thrust faults caused by a compressional failure of the cone. The mechanism of faulting and the possible effect of the interior structure of Olympus Mons was investigated using a numerical model for elastic stresses within a Martian volcano, constructed for that purpose. Results of the analysis supports the view that the terraces on Olympus Mons, as well as on other three Martian volcanoes, including Ascraeus Mons, Arsia Mons, and Pavonis Mons are indeed thrust faults.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14345-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    The shallow structure of the Martian lithosphere in the vicinity of the ridged plains (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: On Mars, the most prominent assemblage of regularly spaced plain ridges occurs in the plains of the Coprates and Lunae Planum regions. In this paper, a number of tectonic models is developed and quantitatively evaluated, that relate the regular spacing of these ridges to the shallow internal structure of Mars. It is shown that models with both rigid and deformable megaregolith-basement interface conditions can provide solutions which can explain the ridge spacing within the constraint provided by the estimated thickness of the smooth plains materials. Implications of the models for the structure and state of stress in the Tharsis region at the time of ridge formation are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14215-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Speculations on the origin and evolution of the Utopia-Elysium lowlands of Mars (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: This paper proposes a qualitative model for the origin of the Utopia-Elysium northern lowlands on eastern Mars in terms of the long-term evolution of two large overlapping impact basins. The model, which is consistent with both the observed geologic constraints and more quantitative results obtained by numerical modeling of smaller (Orientale-size) impact basins, is shown to qualitatively account for the major topographic variation seen in the Utopia-Elysium region, including the overall 'lowness' of the area and localized depressions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14203-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    Discontinuities in the shallow Martian crust at Lunae, Syria, and Sinai Plana (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Detailed photoclinometric data are presented for a variety of surface features (pits, troughs, wall valleys, and grabens) within three study areas in the western equatorial regions of Mars (Lunae, Syria, and Sinai Plana) that provide evidence for mechanical discontinuities within the shallow Martian crust in these regions. The data's relation to some of the previously proposed mechanical discontinuities within the Martian crust is discussed, and the geologic significance of these features is speculated upon.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14231-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    A new survey of multiring impact basins on Mars (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Literature data on Martian multiring impact basins with diameters greater than 500 km are summarized, and evidence is found for eight new such basins. The pattern of changes of basin morphology with increasing basin size suggests three subclasses of multiring basins: (1) multiring basins with diameters up to about 1850 km, which are characterized by the Orientale type concentric structure and cumulative frequency power law slope of -0.75; (2) the Argyre-type basins (with diameters between 1850 and 3600 km, defined by rugged concentric annnuli and a power law slope of nearly -2.0; and (3) the Chryse-type basins (with diameters greater than 3600 km), which exhibit multiple concentric rings and very shallow topographic profiles. Multiring basins are found in all parts of Mars, including the northern lowlands, Tharsis, and surrounding highlands, and are associated with much of the subsequent resurfacing of cratered terrain.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14175-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    Mars gravity field error analysis from simulated radio tracking of Mars Observer (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Results are presented on the analysis of the recovery of the Martian gravity field from tracking data in the presence of unmodeled error effects associated with different orbit orientations. The analysis was based on the mission plan for the Mars Observer (MO) radio tracking data from the Deep Space Network. From the analysis, a conservative estimate of the gravitational accuracy for the entire mission could be obtained. The results suggest that, because the atmospheric drag is the dominant error source, the spacecraft orbit could possibly be raised in altitude without a significant loss of gravitational signal. A change in altitude will also alleviate the large effects seen in the spectrum the satellite resonant orders.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 14155-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Solitons induced by boundary conditions from the Boussinesq equation (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The behavior of solitons induced by boundary excitation is investigated at various time-dependent conditions and different unperturbed water depths, using the Korteweg-de Vries (KdV) equation. Then, solitons induced from Boussinesq equations under similar conditions were studied, making it possible to remove the restriction in the KdV equation and to treat soliton head-on collisions (as well as overtaking collisions) and reflections. It is found that the results obtained from the KdV and the Boussinesq equations are in good agreement.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids A (ISSN 0899-8213); 2; 1574-158
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    Martian impact craters - Correlations of ejecta and interior morphologies with diameter, latitude, and terrain (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An effort is made to establish the ability of a correlation between crater morphology and latitude, diameter, and terrain, to discriminate among the effects of impact energy, atmosphere, and subsurface volatiles in 3819 larger-than-8 km diameter craters distributed over the Martian surface. It is noted that changes in ejecta and interior morphology correlate with increases in crater diameter, and that while many of the interior structures exhibit distributions interpretable as terrain-dependent, central peak and peak ring interior morphologies exhibit minimal relationships with planetary properties.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 87; 156-179
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    Hopf bifurcation in the driven cavity (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The algorithm employed in the present incompressible two-dimensional calculations of an impulsively-started lid-driven cavity has its basis in the time-dependent stream-function equation. While a Crank-Nicholson differencing scheme is used for the diffusion terms, the Adams-Bashforth scheme is used for the convection terms. The periodic asymptotic solutions obtained for Reynolds numbers of 5000 and 10,000 are found to be precisely periodic; it is demonstrated that they have reached asymptotic states. The indicators of that achievement are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 90; 219-261
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    A goal and strategy for human exploration of the moon and Mars (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Eventual settlement of the solar system, beginning with the moon and Mars, is proposed, and a strategy for the exploration of and initial settlement of the moon and Mars, based on the model of European settlement of the Americas, is discussed. Strategies suggest an allocation of functions between humans and telerobots to conduct the exploration and initial settlement.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Space Policy (ISSN 0265-9646); 6; 195-208
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    Large-scale patterns of eolian sediment transport on Venus - Predictions for Magellan (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The atmosphere of Venus is likely to exert a major influence on the surface. Arecibo and Venera 15/16 observations of the population of impact craters with bright halos give direct evidence of surface modification, on the scale of centimeters, to smooth the surface on time scales of 50 - 250 my. Both chemical and mechanical modifications probably occur. Diurnal winds in the planetary boundary layer can transport particles. Using boundary layer theory, including the effects of topography, surface stresses and resulting transport and deposition of sand-size particles are calculated. Regional slopes are sites of largest surface stresses. Sand will be generally transported downhill, although there is a preferential net transport from east to west, in the same direction as the atmospheric superrotation. It is predicted here that streaks may be seen in the Magellan radar images which will indicate directions of net eolian transport on the surface of Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1365-136
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    Small domes on Venus - Probable analogs of Icelandic lava shields (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: On the basis of observed shapes and volumetric estimates, small, dome-like features on radar images of Venus are interpreted to be analogs of Icelandic lava-shield volcanoes. Morphometric data for Venusian domes in Aubele and Slyuta as well as measurements of representative dome volumes and areas from Tethus Regio are used to demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1381-138
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    Geologic evidence of hotspot activity of Venus - Predictions for Magellan (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A number of distinctive types of geologic features have been identified on Venus that are interpreted to be related to thermal plumes including domal rises, coronae, and major composite shield volcanoes. The basic characteristics of these features as well as their distribution are documented. The three types of features have related morphologies and are interpreted to represent a continuum of features formed by mantle plumes at scales from 100s to over 1000 km. The Artemis structure, located in Aphrodite Terra, is proposed to be a large corona. If crustal spreading processes are operating on Venus, hotspot features should form chains on the surface as seen in terrestrial ocean basins. On the basis of current data on hotspot-related feature distribution on Venus, no clear evidence exists for hotspot chains. The complete distribution of hotspot features in Magellan data will be used to understand better the relationship between interior processes and surface features, as well as to provide a test for the crustal spreading hypothesis.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1377-138
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    Radar characteristics of the equatorial plains of Venus from Goldstone observations - Implications for interpretation of Magellan data (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Based on analyses of recent high resolution observations of the approximately 1000 km diameter Heng-O ring structure by the Goldstone Solar System Radar, it is predicted that the structure is a large corona. Calibrated values of radar backscatter coefficient indicate lateral variations of a factor of 4 in Fresnel reflectivity in the vicinity of Heng-O, as well as in other areas of the plains, at scales of tens of km. It is predicted that areas with very low reflectivity values, which occur in a variety of geological settings, are soil-dominated, with bulk densities as low as 1.5 g/cu cm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 1357-136
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    Containments for liquids at zero gravity (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A theory proposed by Concus and Finn (1974) and recently developed by Finn (1983 and 1984) yields explicit geometrical criteria for the position of the free surface of a liquid at zero gravity in a cylindrical container of specified cross section. These criteria were applied by Concus and Finn to three container geometries: the bathtub, the trapezoid, and the keyhole. It is possible to find geometrical criteria that promise a liquid interface of finite height, with the base still covered with liquid, or a liquid interface of infinite height, with the liquid wetting a well defined portion of the wall. In the present work, calculations are presented for a fourth geometry, the non-concentric cylinders. In addition, the earlier calculations of Concus and Finn are extended, and a unified graphical presentation of all four geometries is given that can be used directly for the design of containments for liquids at zero gravity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Microgravity Science and Technology (ISSN 0938-0108); 3; 13-23
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    Titan and other icy satellites - Dielectric properties of constituent materials and implications for radar sounding (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Radar sounding observations of Titan and the other outer solar system icy satellites have been conducted in order to ascertain the materials present, their dielectric properties, and the degree of radar signal penetration. Deep penetration is possible at long wavelengths, while strong reflections may occur due to pockets or layers of H2O-NH3 solution. Attention is given to the case of Titan, using models to calculate radar reflection S/N ratios; the models involve H2O ice covered by a 100-m thick layer of organic sediments that are overlain by an ocean of liquid CH4-C2H6-N2. At 13.6-cm wavelength, a greater-than-10 dB S/N is computed from the ocean-sediment and sediment-ice interfaces, suggesting that the geology of Titan may be investigated by such a sounding mode despite deep ocean coverage of the satellite.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 86; 336-354
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    A spectrum model for weakly anisotropic turbulence (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A simple model, parameterized by the Reynolds stress anisotropy, is proposed for the spectrum of weakly anisotropic turbulence. It contains a model constant that affects its region of realizability. This spectrum model is used to derive a one-point closure to the rapid pressure-strain term. The derived pressure-strain model is linear in the Reynolds stress anisotropy and is of the same form as the closure model of Launder et al. (1975). The spectrum model becomes unrealizable in some regions of wave space for sufficiently large anisotropy of the Reynolds stress, and this is used to infer the region of validity of the linear closure model. It is found that the extent of the valid region is very small when the model constant is set to match rapid distortion theory, and largest for a model-constant set close to the value suggested by LRR. However, even the largest valid domain does not extend very far from isotropy, suggesting inherent weakness in the linear pressure-strain models.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids A (ISSN 0899-8213); 2; 1500-150
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    A technique for measurement of instantaneous heat transfer in steady-flow ambient-temperature facilities (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An experimental technique is described for obtaining time-resolved heat flux measurements with high-frequency response (up to 100 kHz) in a steady-flow ambient-temperature facility. The heat transfer test object is preheated and suddenly injected into an established steady flow. Thin-film gages deposited on the test surface detect the unsteady substrate surface temperature. Analog circuitry designed for use in short-duration facilities and based on one-dimensional semiinfinite heat conduction is used to perform the temperature/heat flux transformation. A detailed description of substrate properties, instrumentation, experimental procedure, and data reduction is given, along with representative results obtained in the stagnation region of a circular cylinder subjected to a wake-dominated unsteady flow. An in-depth discussion of related work is also provided.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Experimental Thermal and Fluid Science (ISSN 0894-1777); 3; 416-430
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    The deep atmosphere of Venus revealed by high-resolution nightside spectra (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The first high-resolution spectroscopic observations of the night side of Venus obtained in two narrow spectral windows centered at 1.74 and 2.3 microns, where the nightside is anomalously bright, are reported. Absorption features from CO2, CO, H2O, HDO, HCl, HF, and COS are detected, and there are a number of unidentified features. A preliminary analysis indicates that the observed radiation is thermal emission from atmospheric layers in the eight-bar pressure region for the 2.3 micron window and even deeper at 1.7 micron. The derived CO and H2O abundances agree with in situ Pioneer measurements in the deep troposphere and are consistent with the high deuterium enrichment inferred from Pioneer data. The first measurements of HCl and HF below the clouds are reported along with the first firm detection of COS.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 345; 508-511
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    Near-wall turbulence model and its application to fully developed turbulent channel and pipe flows (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A near-wall turbulence model and its incorporation into a multiple-timescale turbulence model are presented. The near-wall turbulence model is obtained from a k-equation turbulence model and a near-wall analysis. In the method, the equations for the conservation of mass, momentum, and turbulent kinetic energy are integrated up to the wall, and the energy transfer and the dissipation rates inside the near-wall layer are obtained from algebraic equations. Fully developed turbulent channel and pipe flows are solved using a finite element method. The computational results compare favorably with experimental data. It is also shown that the turbulence model can resolve the overshoot phenomena of the turbulent kinetic energy and the dissipation rate in the region very close to the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Numerical Heat Transfer, Part B: Fundamentals (ISSN 1040-7790); 17; 101-122
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    Mars ionopause during solar minimum - A lesson from Venus (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The ion densities measured by the Viking landers (Hanson et al., 1977) do not show an abrupt falloff with height, giving the false impression that Mars has no ionopause. On the basis of knowledge gained from the solar wind interaction at Venus during solar minimum, it is demonstrated that the observed O2 profile above about 160 km on Mars is a distributed photodynamical ionosphere and can produce an ionopause at around 325 km, similar to that observed on Venus during solar minimum. It is concluded that the solar wind interacts directly with the Mars ionosphere, suggesting that the planet does not have an intrinsic magnetic field of any consequence.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 8265-826
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...