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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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Nonlinear theory of elastic directed surfaces.
Nonlinear theory for deformation of elastic directed surface, assuming existence of strain energy function and postulating virtual work governing mechanical behavior
Dissipative systems
The abstract theory presented shows how the theory of dissipative systems of ordinary differential equations can be extended to include a wide class of functional and partial differential equations. Since the basic hypotheses are all in terms of boundedness, finding sufficient conditions in terms of Liapunov functions was not difficult. Work is being undertaken to solve some nontrivial examples to illustrate how the theory can applied.
Heat pipe design handbook, part 2
The utilization of a digital computer code for heat pipe analysis and design (HPAD) is described which calculates the steady state hydrodynamic heat transport capability of a heat pipe with a particular wick configuration, the working fluid being a function of wick cross-sectional area. Heat load, orientation, operating temperature, and heat pipe geometry are specified. Both one 'g' and zero 'g' environments are considered, and, at the user's option, the code will also perform a weight analysis and will calculate heat pipe temperature drops. The central porous slab, circumferential porous wick, arterial wick, annular wick, and axial rectangular grooves are the wick configurations which HPAD has the capability of analyzing. For Vol. 1, see N74-22569.
The design and use of an error correction information system for NASTRAN
Error Correction Information System (ECIS) is a system for a two-way transmittal of NASTRAN maintenance information via a data base stored on a nationwide accessible computer. ECIS consists of two data bases. The first data base is used for comments, reporting NASTRAN Software Problem Reports (SPR's) and bookkeeping information which can be updated by the user or the NASTRAN Office. The second data base is used by the NSMO to store all SPR information and updates. The hardware needed by an accessing user is any desktop computer terminal and a telephone to communicate with the central computer. The instruction format is an engineering oriented language and requires less than an hour to obtain a working knowledge of its functions.
Quantitative analysis of autoradiographic image intensification using Thiourea-S35
Photographic images enhanced by the method of Thiourea-S35 autoradiography are evaluated in terms of signal-to-noise ratio, detective quantum efficiency (DQE), and Wiener spectrum analysis using digitized images. It is determined that the original signal-to-noise ratio is not degraded by the intensification process which allows an increase in the practical working DQE as a function of density. These results apply at all spatial frequencies that were tested. The advantage given by autoradiography is the ability to produce usable images from emulsions originally exposed to the low densities corresponding to maximum DQE and movement of faint image densities above the level of the threshold for detection.
Characterizing the scientific potential of satellite sensors
Eleven thematic mapper (TM) radiometric calibration programs were tested and evaluated in support of the task to characterize the potential of LANDSAT TM digital imagery for scientific investigations in the Earth sciences and terrestrial physics. Three software errors related to integer overflow, divide by zero, and nonexist file group were found and solved. Raw, calibrated, and corrected image groups that were created and stored on the Barker2 disk are enumerated. Black and white pixel print files were created for various subscenes of a San Francisco scene (ID 40392-18152). The development of linear regression software is discussed. The output of the software and its function are described. Future work in TM radiometric calibration, image processing, and software development is outlined.
Hydrogen-like atoms on the surface of neutron stars - Intense magnetic field effects
It is known that very strong (greater than 1-TG) magnetic fields exist on the surface of some neutron stars. The properties of atoms in fields of this nature are considerably different from those of atoms in field-free regions. Because of the mixing of spherical and cylindrical symmetries, the analytical solution to the problem of a hydrogen atom in a uniform magnetic field is impossible to obtain. In this work, a variational wave function is used to describe the properties of hydrogen like atoms in intense magnetic fields including first-order relativistic effects. Special attention is given to the transition matrix elements for the 2p(0) - 1s(0) transition in Fe XXVI.
Diffusion length measurements in bulk and epitaxially grown 3-5 semiconductors using charge collection microscopy
Diffusion lengths and surface recombination velocities were measured in GaAs diodes and InP finished solar cells. The basic techniques used was charge collection microscopy also known as electron beam induced current (EBIC). The normalized currents and distances from the pn junction were read directly from the calibrated curves obtained while using the line scan mode in an SEM. These values were then equated to integral and infinite series expressions resulting from the solution of the diffusion equation with both extended generation and point generation functions. This expands previous work by examining both thin and thick samples. The surface recombination velocity was either treated as an unknown in a system of two equations, or measured directly using low e(-) beam accelerating voltages. These techniques give accurate results by accounting for the effects of surface recombination and the finite size of the generation volume.
Diffusion length measurement in bulk and epitaxially grown III-V semiconductors using charge collection microscopy
Diffusion lengths and surface recombination velocities were measured in GaAs diodes and InP finished solar cells. The basic technique used was charge collection microscopy, also known as electron beam induced current (EBIC). The normalized currents and distances from the pn junction were read directly from the calibrated curves obtained while using the line-scan mode in an SEM. These values were then equated to integral and infinite series expressions resulting from the solution of the diffusion equation with both extended-generation and point-generation functions. This expands previous work by examining both thin and thick samples. The surface recombination velocity was either treated as an unknown in a system of two equations or measured directly using low e(-) beam accelerating voltages. These techniques give accurate results by accounting for the effects of surface recombination and the finite size of the generation volume.
Mission Operations and Data Systems Directorate's operational/development network (MODNET) at Goddard Space Flight Center
A brief, informal narrative is provided that summarizes the results of all work accomplished during the period of the contract; June 1, 1987 through September 30, 1988; in support of Mission Operations and Data Systems Directorate's Operational Development Network (MODNET). It includes descriptions of work performed in each functional area and recommendations and conclusions based on the experience and results obtained.
Attitude Determination and Control System (ADCS) and Maintenance and Diagnostic System (MDS): A maintenance and diagnostic system for Space Station Freedom
The Maintenance and Diagnostic System (MDS) that is being developed at Honeywell to enhance the Fault Detection Isolation and Recovery system (FDIR) for the Attitude Determination and Control System on Space Station Freedom is described. The MDS demonstrates ways that AI-based techniques can be used to improve the maintainability and safety of the Station by helping to resolve fault anomalies that cannot be fully determined by built-in-test, by providing predictive maintenance capabilities, and by providing expert maintenance assistance. The MDS will address the problems associated with reasoning about dynamic, continuous information versus only about static data, the concerns of porting software based on AI techniques to embedded targets, and the difficulties associated with real-time response. An initial prototype was built of the MDS. The prototype executes on Sun and IBM PS/2 hardware and is implemented in the Common Lisp; further work will evaluate its functionality and develop mechanisms to port the code to Ada.
Development of the Single Graded Groove high-performance heat pipe
This paper describes the development of a new nonarterial heat pipe with a nominal transport capability of 100,000 W in. Data are presented for one-g transport capability as a function of tilt and working fluid quantity. The transport capability agrees well with theoretical predictions. The LMSC Graded Groove Heat Pipe exhibits the high throughput and excellent heat transfer characteristics of earlier arterial designs such as the LMSC Tapered Artery Heat Pipe. At the same time, it suffers none of the priming difficulties associated with the arterial designs.
Exercise/recreation facility for a Lunar or Mars analog
Discussed here is a project to design an exercise/recreation station for an earth based simulator of a lunar or Martian habitat. Specifically, researchers designed a stationary bicycle that will help people keep fit and prevent muscular atrophy while stationed in space. To help with motivation and provide an element of recreation during the workout, the bicycle is enhanced by a virtual reality system. The system will simulate various riding situations and the choice of mountain bike or road bike. The bike employs a magnetic brake that provides continuously changing tension to simulate actual riding conditions. This braking system will be interfaced directly with the virtual reality system. Also integrated into the virtual reality system will be a monitoring system that regulates heart rate, work rate, and other functions during the course of the session.
Exercise/recreation facility for a lunar or Mars analog
The University of Idaho, NASA/USRA project for the 1990-91 school year is an exercise/recreation station for an Earth-based simulator of a lunar or martian habitat. Specifically, a stationary bicycle that will help people keep fit and prevent muscular atrophy while stationed in space was designed. To help with motivation and provide an element of recreation during the workout, the bicycle is to be enhanced by a virtual reality system. The system simulates various riding situations, including the choice of a mountain bike or a road bike. The bike employs a magnetic brake that provides continuously changing tension to simulate actual riding conditions. This braking system is interfaced directly with the virtual reality system. Also, integrated into the virtual reality display will be a monitoring system that regulates heart rate, work rate, and other functions during the course of the session.
Wavelength dependence of limb-darkening of Mars from visible and near-IR telescopic spectral imaging
We are investigating the photometric properties of Mars using Earthbased telescopic spectral imaging obtained during 1988. Each spatial pixel consists of 300 spectral channels from 0.44 to 1.02 microns, calibrated to radiance factor (r(sub F)) through a careful procedure involving standard star observations in 1988 and 1990. Calibrated data include 3 spectral images with solar phase angle (g) of 12 degrees and 4 images with g of 4 degrees. Pixels near the sub-Earth point have a spatial footprint of about 280 x 150 km. Preliminary work using Hapke photometric function reveals a dependence of both single-scattering albedo and roughness parameter on wavelength. The former is in agreement with observed spectra of the martian surface, but the latter is unexpected.
Compressibility effects on rotor forces in the leakage path between a shrouded pump impeller and its housing
A modified approach to Childs' previous work on fluid-structure interaction forces in the leakage path between an impeller shroud and its housing is presented in this paper. Three governing equations consisting of continuity, path-momentum, and circumferential-momentum equations were developed to describe the leakage path inside a pump impeller. Radial displacement perturbations were used to solve for radial and circumferential force coefficients. In addition, impeller-discharge pressure disturbances were used to obtain pressure oscillation responses due to precessing impeller pressure wave pattern. Childs' model was modified from an incompressible model to a compressible barotropic-fluid model (the density of the working fluid is a function of the pressure and a constant temperature only). Results obtained from this model yielded interaction forces for radial and circumferential force coefficients. Radial and circumferential forces define reaction forces within the impeller leakage path. An acoustic model for the same leakage path was also developed. The convective, Coriolis, and centrifugal acceleration terms are removed from the compressible model to obtain the acoustics model. A solution due to impeller discharge pressure disturbances model was also developed for the compressible and acoustics models. The results from these modifications are used to determine what effects additional perturbation terms in the compressible model have on the acoustic model. The results show that the additional fluid mechanics terms in the compressible model cause resonances (peaks) in the force coefficient response curves. However, these peaks only occurred at high values of inlet circumferential velocity ratios greater than 0.7. The peak pressure oscillation was shown to occur at the wearing ring seal. Introduction of impeller discharge disturbances with n = 11 diametral nodes showed that maximum peak pressure oscillations occurred at nondimensional precession frequencies of f = 6.4 and f = 7.8 for this particular pump. Bolleter's results suggest that for peak pressure oscillations to occur at the wearing ring seal, the nondimensional excitation frequency should be on the order of f = 2.182 for n = 11. The resonances found in this research do not match the excitation frequencies predicted by Bolleter. At the predicted peak excitation frequencies given by Bolleter, the compressible model shows an attenuation of the pressure oscillations at the seal exit. The compressibility of the fluid does not have a significant influence on the model at low values of nondimensional excitation frequency. At high values of nondimensional frequency, the effects of compressibility become more significant. For the acoustic analysis, the convective, Coriolis, and centrifugal acceleration terms do affect the results to a limited extent for precession excitation and to a large extent for a pressure excitation when the fluid operates at relatively high Mach numbers.
The use of interactive computer vision and robot hand controllers for enhancing manufacturing safety
Current available robotic systems provide limited support for CAD-based model-driven visualization, sensing algorithm development and integration, and automated graphical planning systems. This paper describes ongoing work which provides the functionality necessary to apply advanced robotics to automated manufacturing and assembly operations. An interface has been built which incorporates 6-DOF tactile manipulation, displays for three dimensional graphical models, and automated tracking functions which depend on automated machine vision. A set of tools for single and multiple focal plane sensor image processing and understanding has been demonstrated which utilizes object recognition models. The resulting tool will enable sensing and planning from computationally simple graphical objects. A synergistic interplay between human and operator vision is created from programmable feedback received from the controller. This approach can be used as the basis for implementing enhanced safety in automated robotics manufacturing, assembly, repair and inspection tasks in both ground and space applications. Thus, an interactive capability has been developed to match the modeled environment to the real task environment for safe and predictable task execution.