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At least 343 records · Page 19

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NASA NTRS1984

Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

Advanced composite aircraft designs include fault-tolerant computer-based digital control systems with thigh reliability requirements for adverse as well as optimum operating environments. Since aircraft penetrate intense electromagnetic fields during thunderstorms, onboard computer systems maya be subjected to field-induced transient voltages and currents resulting in functional error modes which are collectively referred to as digital system upset. A methodology was developed for assessing the upset susceptibility of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general-purpose microprocessor were studied via tests which involved the random input of analog transients which model lightning-induced signals onto interface lines of an 8080-based microcomputer from which upset error data were recorded. The application of Markov modeling to upset susceptibility estimation is discussed and a stochastic model development.

Belcastro, C. M.↗

NASA NTRS1985

Ultrasound instrumentation for the 7 inch Mach seven tunnel

The use of an Apple II+ microcomputer to collect data during the operation of the 7 inch Mach Seven Tunnel is discussed. A method by which the contamination of liquid oxygen is monitored with sound speed techniques is investigated. The electrical equivalent of a transducer bonded to a high pressure fill plug is studied. The three areas are briefly explained and data gathered for each area are presented.

Mazel, D. S.↗

NASA NTRS1985

Mathematical models for space shuttle ground systems

Math models are a series of algorithms, comprised of algebraic equations and Boolean Logic. At Kennedy Space Center, math models for the Space Shuttle Systems are performed utilizing the Honeywell 66/80 digital computers, Modcomp II/45 Minicomputers and special purpose hardware simulators (MicroComputers). The Shuttle Ground Operations Simulator operating system provides the language formats, subroutines, queueing schemes, execution modes and support software to write, maintain and execute the models. The ground systems presented consist primarily of the Liquid Oxygen and Liquid Hydrogen Cryogenic Propellant Systems, as well as liquid oxygen External Tank Gaseous Oxygen Vent Hood/Arm and the Vehicle Assembly Building (VAB) High Bay Cells. The purpose of math modeling is to simulate the ground hardware systems and to provide an environment for testing in a benign mode. This capability allows the engineers to check out application software for loading and launching the vehicle, and to verify the Checkout, Control, & Monitor Subsystem within the Launch Processing System. It is also used to train operators and to predict system response and status in various configurations (normal operations, emergency and contingent operations), including untried configurations or those too dangerous to try under real conditions, i.e., failure modes.

Tory, E. G.↗

NASA NTRS1984

Partial Reflection D-region Electron Densities

The differential absorption technique of measuring electron densities as a function of height in the D region is discussed. In the basic experiment, pulses of medium or high frequency, usually at a fixed frequency (2 to MHz), are radiated upwards with known wave polarizatin (usually linear or circular) from a transmitter at ground level. Partial reflections, from ionospheric scatterers at heights below the E region, are received at the ground, and are resolved into two characteristic components, the ordinary (0) and extraordinary (E) modes whose amplitude ration A(x)/A(o) is then measured as a function of height, h. The heights of these are determined by delay times, the group retardation being minimal in the undisturbed D-region. The electronic system can be very simple. Power splitters and quadrature networks to separate the A(x) and A(o) components are commercially available at low prices and an A-D converter, height-gate system, and microcomputer allows the real-time calculation of mean amplitudes. The ratio of the coefficients of reflection of the two modes, as they originate at each reflection height is then calculable.

Manson, A. H.↗

NASA NTRS1985

Digital temperature and velocity control of mach 0.3 atmospheric pressure durability testing burner rigs in long time, unattended cyclic testing

Hardware and software were developed to implement the hybrid digital control of two Jet A-1 fueled Mach 0.3 burners from startup to completion of a preset number of hot corrosion flame durability cycle tests of materials at 1652 F. This was accomplished by use of a basic language programmable microcomputer and data aquisition and control unit connected together by the IEEE-488 Bus. The absolute specimen temperature was controlled to + or - 3 F by use of digital adjustment of the fuel flow using a P-I-D (Proportional-Integral-Derivative) control algorithm. The specimen temperature was within + or - 2 F of the set point more than 90 percent of the time. Pressure control was achieved by digital adjustment of the combustion air flow using a proportional control algorithm. The burner pressure was controlled at 1.0 + or - 0.02 psig. Logic schemes were incorporated into the system to protect the test specimen from abnormal test conditions in the event of a hardware of software malfunction.

Deadmore, D. L.↗

NASA NTRS1984

Remote sensing research for agricultural applications

Materials and methods used to characterize selected soil properties and agricultural crops in San Joaquin County, California are described. Results show that: (1) the location and widths of TM bands are suitable for detecting differences in selected soil properties; (2) the number of TM spectral bands allows the quantification of soil spectral curve form and magnitude; and (3) the spatial and geometric quality of TM data allows for the discrimination and quantification of within field variability of soil properties. The design of the LANDSAT based multiple crop acreage estimation experiment for the Idaho Department of Water Resources is described including the use of U.C. Berkeley's Survey Modeling Planning Model. Progress made on Peditor software development on MIDAS, and cooperative computing using local and remote systems is reported as well as development of MIDAS microcomputer systems.

Colwell, R. N.↗

NASA NTRS1985

A SLAM II simulation model for analyzing space station mission processing requirements

Space station mission processing is modeled via the SLAM 2 simulation language on an IBM 4381 mainframe and an IBM PC microcomputer with 620K RAM, two double-sided disk drives and an 8087 coprocessor chip. Using a time phased mission (payload) schedule and parameters associated with the mission, orbiter (space shuttle) and ground facility databases, estimates for ground facility utilization are computed. Simulation output associated with the science and applications database is used to assess alternative mission schedules.

Linton, D. G.↗

NASA NTRS1985

Large deflections of a cantilever beam under arbitrarily directed tip load

The nonlinear beam equation was integrated numerically in a direct fashion to obtain results for large deflections of cantilevers under tip loads of arbitrary direction. A short BASIC computer program for performing this integration is presented. Results for selected load cases are presented. The numerical process is performed rapidly on a modern microcomputer, and comparisons with results from closed form solutions show that the process is accurate.

Mccomb, H. E., Jr.↗

NASA NTRS1985

Demonstration project: Putting the bioastronautics data book on line

The possibilities for prototyping electronic document designs using existing microcomputer software are considered. An initial prototype of a hierarchically structured design that includes both text and graphics from a section of the Bioastronautics Data Book are considered.

Travis, I. L.↗

NASA NTRS1985

System enhancements of Mesoscale Analysis and Space Sensor (MASS) computer system

The interactive information processing for the mesoscale analysis and space sensor (MASS) program is reported. The development and implementation of new spaceborne remote sensing technology to observe and measure atmospheric processes is described. The space measurements and conventional observational data are processed together to gain an improved understanding of the mesoscale structure and dynamical evolution of the atmosphere relative to cloud development and precipitation processes. A Research Computer System consisting of three primary computers was developed (HP-1000F, Perkin-Elmer 3250, and Harris/6) which provides a wide range of capabilities for processing and displaying interactively large volumes of remote sensing data. The development of a MASS data base management and analysis system on the HP-1000F computer and extending these capabilities by integration with the Perkin-Elmer and Harris/6 computers using the MSFC's Apple III microcomputer workstations is described. The objectives are: to design hardware enhancements for computer integration and to provide data conversion and transfer between machines.

Hickey, J. S.↗

NASA NTRS1985

Forth system for coherent-scatter radar data acquisition and processing

A real time collection system was developed for the Urbana coherent scatter radar system. The new system, designed for use with a microcomputer, has several advantages over the old system implemented with a minicomputer. The software used to collect the data is described as well as the processing software used to analyze the data. In addition a magnetic tape format for coherent scatter data exchange is given.

Rennier, A. D.↗

NASA NTRS1985

A cluster analysis method for identification of subpopulations of cells in flow cytometric list-mode arrays

A specialized program was developed for flow cytometric list-mode data using an heirarchical tree method for identifying and enumerating individual subpopulations, the method of principal components for a two-dimensional display of 6-parameter data array, and a standard sorting algorithm for characterizing subpopulations. The program was tested against a published data set subjected to cluster analysis and experimental data sets from controlled flow cytometry experiments using a Coulter Electronics EPICS V Cell Sorter. A version of the program in compiled BASIC is usable on a 16-bit microcomputer with the MS-DOS operating system. It is specialized for 6 parameters and up to 20,000 cells. Its two-dimensional display of Euclidean distances reveals clusters clearly, as does its 1-dimensional display. The identified subpopulations can, in suitable experiments, be related to functional subpopulations of cells.

Li, Z. K.↗

NASA NTRS1984

Hardware schemes for fast Fourier transform, part 7.4A

Real-time fast fourier transformer (FFT) processing of a MST radar data and cost-effective approaches to hardware FFT generation were studied. Previously devised hardware FFT configurations are described including the estimated number of chips used and the time required to perform a 1024-point FFT. The remaining entries in the table correspond to original designs, which presuppose the availability of a microcomputer and a modestly complicated hardware peripheral. These original designs, all of which implement a radix-4 FFT with twiddle factors, are assigned model numbers to make them easier to refer to.

Stitt, G. R.↗

NASA NTRS1984

Network ST radar and related measurements at Pennsylvania State University

Mesoscale meteorological measurements, analysis and prediction are some of the principal areas of research in the Department of Meteorology at Penn State. In anticipation of a staged turn-on of the three systems during the Summer and Fall of 1984, the nonconstruction-related efforts have focused on the software development necessary to allow essentially immediate use of network data. A 16-bit microcomputer has been programmed to serve as the network controller, communications interface and, at least for real-time purposes, the operational display system. Insofar as possible we have in this task built upon our substantial accumulated experience in working with the processing and display of Doppler sodar system signals. Once the radar-derived wind and turbulence profiles are communicated to the various interconnected Departmental computers they become just one component of a comprehensive data base which can be applied to a diverse set of ongoing basic and operational research programs.

Thomson, D. W.↗

NASA NTRS1984

Experimental studies of glass refining

The basic components of the experimental apparatus were selected and acquired. Techniques were developed for the fabrication of the special crucibles necessary for the experiments. Arrangements were made for the analysis of glass and gas bubble samples for composition information. Donations of major equipment were received for this project from Owens, Illinois where a similar study had been conducted a few year ago. Decisions were made regarding the actual glass composition to be used, the gas to be used in the first experiments, and the temperatures at which the experiments should be conducted. A microcomputer was acquired, and work was begun on interfacing the video analyzer to it.

Subramanian, R. S.↗

NASA NTRS1985

Application of thermoluminescence for detection of cascade shower 1: Hardware and software of reader system

A reader system for the detection of cascade showers via luminescence induced by heating sensitive material (BaSO4:Eu) is developed. The reader system is composed of following six instruments: (1) heater, (2) light guide, (3) image intensifier, (4) CCD camera, (5) image processor, (6) microcomputer. The efficiency of these apparatuses and software application for image analysis is reported.

Akashi, M.↗

NASA NTRS1985

NAS - Supercomputing master tool for aeronautics

Features, performance objectives and applications planned for the NASA National Aerodynamics Simulator (NAS) are outlined. NAS was conceived in the 1970s as a means to performing numerical aerodynamic simulations beyond the scope of wind tunnel testing for high-speed flight. Present supercomputers cannot deal with problems exhibiting strongly coupled viscous effects, which are being increasingly more accurately represented by approximations to the full Navier-Stokes equations. Located at the NASA-Ames Center, the NAS will by 1990 comprise a distributed computer network capable of a 4 Gflop computing rate and have a memory capacity of 1 billion 64-bit words. Remote access to the system through UNIX-based microcomputers will be available through land lines and satellite links. New supercomputers will be tested on the system without disturbing ongoing work. The core machine will be a Cray-2 with a 2 Gflop rate.

Bailey, F. R.↗

NASA NTRS1984

Computing and information services at the Jet Propulsion Laboratory - A management approach to a diversity of needs

The Jet Propulsion Laboratory, a research and development organization with about 5,000 employees, presents a complicated set of requirements for an institutional system of computing and informational services. The approach taken by JPL in meeting this challenge is one of controlled flexibility. A central communications network is provided, together with selected computing facilities for common use. At the same time, staff members are given considerable discretion in choosing the mini- and microcomputers that they believe will best serve their needs. Consultation services, computer education, and other support functions are also provided.

Felberg, F. H.↗