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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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Desirable features in a spacecraft modeling code are enumerated. The NASCAP is discussed in terms of its approach to the problem. Samples of problem setup and output are provided which demonstrate the ease with which the program can be used. A simple but interesting case of spacecraft charging is examined, and other applications are discussed.
A study involving the use of coulter counter in studying the effects of neomycin on E. coli, S. aureus and A. aerogenes was completed. The purpose of this was to establish proper technique for enumeration of cells per ml. It was found that inhibitory effects on growth of E. coli and A. aerogenes, both gram negative organisms, were directly related to the concentration of neomycin used. However, in case S. aureus, a gram positive organism, a decreased inhibition was noted at higher concentrations. A paper entitled, Use of Coulter Counter in Studying Effect of Drugs on Cells in Culture 1 - Effects of Neomycin on E. coli, S. aureus and A. aerogenes, is attached in the appendix. Laboratory procedures were also established to study the effects of nucleoside antibiotic cordycepin on He La cell grown in suspension cultures.
The Microbial Load Monitor (MLM) is an automated and computerized system for detection and identification of microorganisms. Additionally, the system is designed to enumerate and provide antimicrobic susceptibility profiles for medically significant bacteria. The system is designed to accomplish these tasks in a time of 13 hours or less versus the traditional time of 24 hours for negatives and 72 hours or more for positives usually required for standard microbiological analysis. The MLM concept differs from other methods of microbial detection in that the system is designed to accept raw untreated clinical samples and to selectively identify each group or species that may be present in a polymicrobic sample.
A variety of procedures were developed for the delineation of areas of land use change using Landsat Multispectral Scanner data and the generation of statistics revealing the nature of the changes involved (i.e., number of acres changed from rural to urban). Techniques of the Image Based Information System were utilized in all stages of the procedure, from logging the Landsat data and registering two frames of imagery, to extracting the changed areas and printing tabulations of land use change in acres. Two alternative methods of delineating land use change are presented while enumerating the steps of the entire process. The Houston, Texas urban area, and the Orlando, Florida urban area, are used as illustrative examples of various procedures.
Platinum electrodes with surface area ratios of four to one were used to detect and enumerate a variety of gram-positive and gram-negative organisms. Linear relationships were established between inoculum size and detection time. End points for platinum electrodes were similar to those obtained with a platinum-reference electrode combination. Shape of the overall response curves and length of detection times for gram-positive organisms were markedly different than those for the majority of gram-negative species. Platinum electrodes are better than the platinum-reference electrode combination because of cost, ease of handling, and clearer definition of the end point.
The paper defines higher dimensional Hadamard matrices and enumerates on some of the simplest three-, four-, and five-dimensional cases and procedures for generating them. Special emphasis is given to proper matrices that have a dimensional hierarchy of orthogonalities. It is determined that this property lends itself primarily to the application of higher dimensional Hadamard matrices to error-correcting codes. A list of derived statements for n-dimensional Hadamard matrices are given, as well as a definition of Hadamard matrix families, such as minimal, Petrie polygon, antipodal (n-2)-dimensional sections, and double proximity shells.
This paper is a description of recent work to categorize and enumerate the various options available for transfer from earth to Saturn orbit. The fundamental period of investigation is the 20-year synodic period of Jupiter and Saturn which permits a scenario of Jupiter gravity assist trajectories for various trip times. Against the background of the Jupiter swingby trajectories are compared a number of other options including Delta V-EGA and VEGA trajectories, direct earth-Saturn transfers, and solar and nuclear electric propulsion options. All are compared and contrasted in the context of expected launch vehicle capabilities and realistic transfer times.
Aerodynamic characteristics of wing model gliders and bird wings in particular are discussed. Wind tunnel measurements and aerodynamics of small Reynolds numbers are enumerated. Airfoil behavior in the critical transition from laminar to turbulent boundary layer, which is more important to bird wing models than to large airplanes, was observed. Experimental results are provided, and an artificial bird wing is described.
Recent studies sponsored by NASA and United States industry indicate a need for technology to handle large space-based antenna systems. These systems will require apertures of up to 100 m and more in order to be capable of radio frequency operation up to Ku-band for communications, earth observations, and radio astronomy applications. They must also be cost-effective and compatible with the Space Transportation System. Selection criteria for the antennas which include such considerations as surface precision in the intended service environment and mechanical packaging efficiency, are enumerated. Space testing of the antennas will be carried out as part of NASA's Large Space Systems Technology (LSST) Program, which will be continued through fiscal year 1984. Deployable antennas have been selected for development by the LSST Program. The maturity of this class of antennas is such that a significant number of near-term space based applications will be satisfied (mobile communications, submillimeter radio astronomy, orbiting deep space relay station ODSRS, orbiting VLBI, earth-looking radiometry). Two antenna concepts selected for development are the offset wrap-rib configuration and the maypole (hoop/column) configuration with details for these concepts presented.
The article describes the solutions near Lagrange's circular collinear configuration in the planar problem of three bodies with three finite masses. The article begins with a detailed review of the properties of Lagrange's collinear solution. Lagrange's quintic equation is derived and several expressions are given for the angular velocity of the rotating frame. The equations of motion are then linearized near the circular collinear solution, and the characteristic equation is also derived in detail. The different types of roots and their corresponding solutions are discussed. The special case of two equal outer masses receives special attention, as well as the special case of two small outer masses. Finally, the fundamental family of periodic solutions is extended by numerical integration all the way up to and past a binary collision orbit. The stability and the bifurcations of this family are briefly enumerated.
A work breakdown structure (WBS) is defined as an enumeration of all work activities in hierarchic refinement of detail which organizes work to be done into short manageable tasks with quantifiable inputs, outputs, schedules, and assigned responsibilities. Some of the characteristics and benefits of the WBS are reviewed, and ways in which these can be developed and applied in software implementation projects are discussed. Although the material is oriented principally toward new-software production tasks, many of the concepts are applicable to continuing maintenance and operations tasks.
It is pointed out that jet transport aircraft operating in the stratosphere (often at 45,000 ft) have proved highly cost-effective and convenient as telescope platforms. The Kuiper Airborne Observatory (KAO) 91-cm telescope is described, with attention given to specifications, pointing and tracking, data handling, instrument development, and costs. It is noted that the observatory makes possible important astronomical research, graduate-level instruction, and the development and testing of rugged, remotely controlled instruments. Contributions made by the KAO to planetary astronomy, extragalactic astronomy, the interstellar medium, and to the study of star formation and evolution are enumerated.
The current and voltage waveshapes associated with the power transitor and the power diode in an example current-or-voltage step-up (buck-boost) converter were analyzed to highlight the problems and possible tradeoffs involved in the design of high voltage high power converters operating at switching frequencies in the range of 100 Khz. Although the fast switching speeds of currently available power diodes and transistors permit converter operation at high switching frequencies, the resulting time rates of changes of current coupled with parasitic inductances in series with the semiconductor switches, produce large repetitive voltage transients across the semiconductor switches, potentially far in excess of the device voltage ratings. The need is established for semiconductor switch protection circuitry to control the peak voltages appearing across the semiconductor switches, as well as to provide the waveshaping action require for a given semiconductor device. The possible tradeoffs, as well as the factors affecting the tradeoffs that must be considered in order to maximize the efficiency of the converters are enumerated.
The technical issues which would either seriously impact or potentially negate the integrity of a solar power satellite program are enumerated. Issues are identified not only relating to the question of engineering feasibility, but also to the equally important areas of environmental and social acceptability and, especially, economic viability. Specific information required for resolution of the issues was developed and a planned overall approach for resolution was identified. Results of these analyses show that 60% of the technical issues can be resolved with analysis only; 10% require only ground testing for resolution; and the remaining 30% require space experiments or demonstrations for resolution. The results also show that 85% resolution of the issues may be accomplished prior to development of a protoype.
LANDSAT data acquired over an agricultural area along with ground enumeration of the same area are used to obtain crop acreage estimates which are better (as measured in terms of bias and variance) than can be obtained from either data source alone. Two basic approaches considered within the AgRISTARS program are a stratified crop acreage estimator and a regression estimator. A statement of the problem was mathematically formulated and some theorems were proved which relate to the variance of the two estimators. For a particular set of data, the regression and stratified estimators are compared in terms of certain easily computed parameters.
An optimum integrated residential photovoltaic array/module is addressed. Nineteen existing or proposed systems intended for residential applications are described. Each of these systems is rated against a comprehensive set of evaluation criteria in an effort to formulate three module design concepts for further study and analysis. This evaluation led to a number of observations which are enumerated and should be considered in future module and array designs. Three module concepts are presented as baseline design approaches to be further analyzed and optimized. These options include: (1) a rectangular, direct mounted, shingle type module; (2) an integrally mounted module with nonconductive exposed elements; and (3) an aluminum framed, stand off module. Preliminary design drawings are presented for each of these module configurations.
A defect-design approach to sizing electrical insulation systems for terrestrial photovoltaic modules is presented. It consists of gathering voltage-breakdown statistics on various thicknesses of candidate insulation films where, for a designated voltage, module failure probabilities for enumerated thickness and number-of-layer film combinations are calculated. Cost analysis then selects the most economical insulation system. A manufacturing yield problem is solved to exemplify the technique. Results for unaged Mylar suggest using fewer layers of thicker films. Defect design incorporates effects of flaws in optimal insulation system selection, and obviates choosing a tolerable failure rate, since the optimization process accomplishes that. Exposure to weathering and voltage stress reduces the voltage-withstanding capability of module insulation films. Defect design, applied to aged polyester films, promises to yield reliable, cost-optimal insulation systems.
This research examines the relationships between aircrew compliance with procedures and operator errors. The data for this analysis were generated by reexamination of a 1976 experiment in full mission simulation conducted by Dr. H. P. Ruffell Smith (1979) for the NASA-Ames Research Center. The character of individual operators, the chemistry of crew composition, and complex aspects of the operational environment affected procedural compliance by crew members. Associations between enumerated operator errors and several objective indicators of crew coordination were investigated. The correspondence among high operator error counts and infrequent compliance with specific crew coordination requirements was most notable when copilots were accountable for control of flight parameters.