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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 739 records · Page 41

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NASA NTRS1991

The use of containerless processing in researching reactive materials

It has recently become possible to perform containerless, high-temperature liquid-phase processing of many nonvolatile materials without resort to orbital microgravity, thereby facilitating the conduct of materials research in conjunction with noncontact diagnostic instruments. The melt-levitation techniques are electromagnetic, aerodynamic, acoustic, aeroacoustic, and electrostatic; nonorbital microgravity conditions are obtainable aboard NASA's KC-135 aircraft on parabolic flight paths, as well as in drop tubes and towers. Applications encompass the purification of metals and the creation of nonequilibrium and metastable structures. Process control and property measurements include optical pyrometry and emissivity, laser polarimetry, and drop calorimetry.

Weber, J. K. R.↗

NASA NTRS1990

Study of flexural rigidity of weavable powder-coated towpreg

An effort has been made to weave powder-impregnated tow into a two-dimensional preform, controlling process variables to obtain high flexural rigidity in the warp direction and greater flexibility in the fill direction. The resulting prepregs have been consolidated into laminates with LaRC-TPI matrices. Complementary SEM and DSC studies have been performed to deepen understanding of the relationship between tow flexibility and heat treatment. Attention is also given to the oven temperature and residence time variables' effects on power/fiber fusion.

Hirt, Douglas E.↗

NASA NTRS1991

Concept of nondestructive evaluation

The history of nondestructive evaluation, a recently evolved basic testing philosophy, and some application of NDE are examined with emphasis on aerospace applications. The discussion covers the definition of NDE, chronological development, NDE methods and systems, the use of NDE for process control, NDE for ceramics and composites, NDE for fracture control in glass, and science aspects of NDE. Specific examples of NDE applications are given.

Chern, E. J.↗

NASA NTRS1992

An investigation of the solar cycle response of odd-nitrogen in the thermosphere

This annual report covers the first year of funding for the study of the solar cycle variations of odd-nitrogen (N((sup 2)D), N((sup 4)S), NO) in the Earth's thermosphere. The study uses the extensive data base generated by the Atmosphere Explorer (AE) satellites, and the Solar Mesosphere Explorer Satellite. The AE data are being used, for the first time, to define the solar variability effect on the odd-nitrogen species through analysis of the emissions at 520 nano-m from N((sup 2)D) and the emission from O(+)((sup 2)P). Additional AE neutral and ion density data are used to help define and quantify the physical processes controlling the variations. The results from the airglow study will be used in the next two years of this study to explain the solar cycle changes in NO measured by the Solar Mesosphere Explorer.

Rusch, David W.↗

NASA NTRS1992

Organic crystal growth experiment facility (13-IML-1)

The interesting nature of metal-like organic compounds composed of charge transfer complexes has been recently realized. Crystals of these complexes can usually be grown by the solution crystallization method. It is difficult to grow such organic crystals on Earth, especially from the chemical reactions through diffusion controlled process in the solutions, because of gravitational disturbances, or sedimentation. The International Microgravity Lab. (IML-1) Organic Crystal Growth with G-Gitter Preventive Measure (OCGP) experiment is expected to grow a single crystal large enough to allow its intrinsic physical properties to be measured and its detailed crystal structure to be determined. This experiment also attempts to assess the experimental conditions including the microgravity environment for further study of the fundamental process of solution crystallization, nucleation, and growth from supersaturated phases including chemical reactions. Microgravity disturbances, G-jitter, may be an important environmental factor in the experimental method to assess. The vibration damping effects on organic crystal growth can be carefully studied.

Kanbayashi, Akio↗

NASA NTRS1992

Dynamics of the atmospheres of the outer planets

Current knowledge about dynamics and the thermal structure of the outer planets is reviewed with the aim of identifying important measurements which should be made in the post-Voyager era. The existence of jets and cloud bands is the puzzle that underlies all others. The discussion focuses on the particular case of Jupiter because the documentation is the most complete. It is argued that the gross dynamical parameters of the outer planetary atmospheres are the keys to their behaviors, rather than the particular specifics of radiative forcing, cloud distributions, or thermodynamic transformations. Voyager data has shown that the jet systems decay with height in the region above the visible clouds. Therefore, the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds. These require the determination of the deep structure of the jets, of the density stratification, and of the horizontal density contrasts. The deep regions are not easily accessible and these measurements present challenging opportunities. Indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere.

Gierasch, Peter J.↗

NASA NTRS1992

An Introduction to Intelligent Processing Programs Developed by the Air Force Manufacturing Technology Directorate

The Air Force has numerous on-going manufacturing and integration development programs (machine tools, composites, metals, assembly, and electronics) which are instrumental in improving productivity in the aerospace industry, but more importantly, have identified strategies and technologies required for the integration of advanced processing equipment. An introduction to four current Air Force Manufacturing Technology Directorate (ManTech) manufacturing areas is provided. Research is being carried out in the following areas: (1) machining initiatives for aerospace subcontractors which provide for advanced technology and innovative manufacturing strategies to increase the capabilities of small shops; (2) innovative approaches to advance machine tool products and manufacturing processes; (3) innovative approaches to advance sensors for process control in machine tools; and (4) efforts currently underway to develop, with the support of industry, the Next Generation Workstation/Machine Controller (Low-End Controller Task).

Sampson, Paul G.↗

NASA NTRS1992

The Role of Lidars in Global Change Research

Recent research has solidified a view of the Earth as a global scale interactive system with complex chemical, physical, biological, and dynamical processes that link the ocean, atmosphere, land, and marine terrestrial living organisms. An important aspect of Earth System Science studies in the future is the need to observe simultaneously the physical, chemical, biological, and dynamical processes involved in highly coupled phenomena such as those mentioned. Lidars operating from the surface, aircraft, and satellites provide a powerful observational technique to study the processes and observe trends important to global change. Lidar observations have already played important roles in helping understand processes controlling stratospheric ozone and aerosols, tropospheric clouds, water vapor, ozone, gaseous pollutants, and aerosols, and winds and temperatures throughout the atmosphere. In this paper the author reviews the science of global change and highlights the potential roles for lidar in studying the Earth system.

Prinn, Ronald G.↗

NASA NTRS1992

Transportable Lidar for the Measurement of Ozone Concentration and Flux Profiles in the Lower Troposphere

In many areas of the United States, as well as in other industrial areas (such as Europe), elevated and potentially harmful levels of ozone are being measured during summer. Most of this ozone is photochemically produced. The relatively long lifetime of ozone allows industrially produced ozone to be transported on a hemispheric scale. Since the trends of tropospheric ozone are very likely dependent on the source strengths and distributions of the pollutants and the chemical/ transport process involved, a predictive understanding of tropospheric ozone climatology requires a focus on the chemical and transport processes that link regional emissions to hemispheric ozone trends and distributions. Of critical importance to these studies is a satisfactory data base of tropospheric ozone distribution from which global and regional tropospheric ozone climatology can be derived, and the processes controlling tropospheric ozone can be better understood. A transportable lidar for measuring ozone concentration and flux profiles in the lower troposphere is needed. One such system is being developed at the National Oceanic and Atmospheric Administration/Earth Resources Laboratory (NOAA/ERL) Wave Propagation Laboratory (WPL).

Zhao, Yanzeng↗

NASA NTRS1992

The O2 reduction at the IFC modified O2 fuel cell electrode

The International Fuel Corporation (IFC) state of the art (SOA) O2 electrode (Au-10 percent Pt electrocatalyst by weight) is currently being used in the alkaline H2-O2 fuel cell in the NASA Space Shuttle. Recently, IFC modified O2 electrode, as a possible replacement for the SOA electrode. In the present study, O2 reduction data were obtained for the modified electrode at temperatures between 23.3 and 91.7 C. BET measurements gave an electrode BET surface area of about 2070 sq. cm/sq. cm of geometric surface area. The Tafel data could be fitted to two straight line regions. The slope for the lower region, designated as the 0.04 V/decade region, was temperature dependent, and the transfer coefficient was about 1.5. The 'apparent' energy of activation for this region was about 19 kcal/mol. An O2 reduction mechanism for this 0.04 region is presented. In the upper region, designated as the 0.08 V/decade region, diffusion may be the controlling process. Tafel data are presented to illustrate the increase in performance with increasing temperature.

Fielder, William L.↗

NASA NTRS1992

Mass loading at Titan and comets

Present understanding of the cometary mass loading process (the addition of newborn ions to high speed magnetized plasma flows) is explored and the cometary lesson is applied to the environment of Titan. Mass loading is the dominant physical process controlling the interaction of the solar wind with comets, and it might play an important role in the interaction of Titan's neutral torus and exosphere with Saturn's magnetosphere. Freshly born ions follow cycloidal trajectories, resulting from the superposition of gyration and E/B drift. In the plasma frame, the resulting velocity space distribution is a ring beam distribution at comets and a ring distribution at Titan. This difference in free energy is expected to generate significantly different levels of low frequency broad band electromagnetic turbulence and, thus, result in important differences in the implanted ion distributions. It is predicted that mass loading creates a hot, equatorially trapped plasma population at Titan.

Gombosi, Tamas I.↗

NASA NTRS1990

Characterization of individual particles in gaseous media by mass spectrometry

An introduction is given to a system for particle analysis by mass spectrometry (PAMS) which employs particle-beam techniques to measure mass spectra on a continuous real-time basis. The system is applied to particles of both organic and inorganic compounds, and the measurements give the chemical characteristics of particles in mixtures and indicate source apportionment. The PAMS system can be used for process control and studying heterogeneous/catalytic reactions in particles, and can be fitted to study the real-time attributes of PAMS.

Sinha, M. P.↗

NASA NTRS1990

Neurocomputing

The present work is intended to give technologists, research scientists, and mathematicians a graduate-level overview of the field of neurocomputing. After exploring the relationship of this field to general neuroscience, attention is given to neural network building blocks, the self-adaptation equations of learning laws, the data-transformation structures of associative networks, and the multilayer data-transformation structures of mapping networks. Also treated are the neurocomputing frontiers of spatiotemporal, stochastic, and hierarchical networks, 'neurosoftware', the creation of neural network-based computers, and neurocomputing applications in sensor processing, control, and data analysis.

Hecht-Nielsen, Robert↗

NASA NTRS1991

Advanced air revitalization for optimized crew and plant environments

The Hybrid Air Revitalization System (HARS) closed ecosystem concept presented encompasses electrochemical CO2 and O2 separators, in conjunction with a mechanical condenser/separator for maintaining CO2, O2, and humidity levels in crew and plant habitats at optimal conditions. HARS requires no expendables, and allows flexible process control on the bases of electrochemical cell current, temperature, and airflow rate variations. HARS capacity can be easily increased through the incorporation of additional chemical cells. Detailed system flowcharts are provided.

Lee, M. G.↗

NASA NTRS1992

Evolution and advection of solar mesogranulation

A three-hour sequence of observations at the Pic du Midi observatory has been obtained which shows the evolution of solar mesogranules from appearance to disappearance with unprecedented clarity. It is seen that the supergranules, which are known to advect the granules with their convective motion, also advect the mesogranules to their boundaries. This process controls the evolution and disappearance of mesogranules.

Muller, Richard↗

NASA NTRS1992

Photochemical partitioning of the reactive nitrogen and chlorine reservoirs in the high-latitude stratosphere

The correlated set of measurements in the lower stratosphere from polar missions of the NASA ER-2 is used to derive partitioning of the major components of the reactive nitrogen and inorganic chlorine reservoirs. The results provide a consistent method for comparing distributions, and hence the controlling processes, between different areas of the near-polar regions. Clear evidence of the effects of heterogeneous processes in the atmosphere is found. Values for NO2, ClONO2, N2O5, and Cl2O2 are derived in a simplified steady-state model based on in situ NO, ClO, O3, temperature, and pressure measurements, laboratory-measured reaction rates; and modeled photodissociation rates. Values for the reservoir totals are independently derived from measurements of N2O, organic chlorine, and total reactive nitrogen. The relative abundances of the measured and derived species within the reservoirs are calculated, and the longer-lived species HCl and HNO3 are estimated as the residuals of their respective reservoirs.

Kawa, S. R.↗

NASA NTRS1992

Thermospheric composition changes seen during a geomagnetic storm

The largest magnitude winds observed using the instruments on board the Dynamics Explorer 2 (DE-2) satellite were measured during the large geomagnetic storm that occurred on November 24, 1982. Neutral temperatures exceeded 2000 K during this storm, and these high temperatures, combined with the very large observed winds and the very full instrumental coverage available in both hemispheres, make it a unique event to study. This paper presents results obtained using these DE-2 data and a time dependent simulation of the event made using the NCAR Thermosphere/Ionosphere General Circulation Model (NCAR-TIGCM). In general, the agreement between model calculations and the data is very good, implying that most of the important physical processes controlling the energetics and dynamics of the thermosphere are reasonably well represented in the model. The modeled summer hemisphere changes in the mass mixing ratio of N2 (Psi(N2)) are in very good agreement with the averaged data in both hemispheres. This paper describes model-experiment comparisons for the November 24, 1982 geomagnetic storm changes.

Burns, A. G.↗

NASA NTRS1991

Information management for commercial aviation - A research perspective

The problem of flight deck information management (IM), defined as processing, controlling, and directing information, for commercial flight decks, and a research effort underway to address this problem, are discussed. The premises provided are utilized to lay the groundwork required for such research by providing a framework to describe IM problems and an avenue to follow when investigating solution concepts. The research issues presented serve to identify specific questions necessary to achieve a better understanding of the IM problem, and to provide assessments of the relative merit of various solution concepts.

Ricks, Wendell R.↗