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At least 685 records · Page 38

Research in the design of high-performance reconfigurable systems

An initial design for the Bit Processor (BP) referred to in prior reports as the Processing Element or PE has been completed. Eight BP's, together with their supporting random-access memory, a 64 k x 9 ROM to perform addition, routing logic, and some additional logic, constitute the components of a single stage. An initial stage design is given. Stages may be combined to perform high-speed fixed or floating point arithmetic. Stages can be configured into a range of arithmetic modules that includes bit-serial one or two-dimensional arrays; one or two dimensional arrays fixed or floating point processors; and specialized uniprocessors, such as long-word arithmetic units. One to eight BP's represent a likely initial chip level. The Stage would then correspond to a first-level pluggable module. As both this project and VLSI CAD/CAM progress, however, it is expected that the chip level would migrate upward to the stage and, perhaps, ultimately the box level. The BP RAM, consisting of two banks, holds only operands and indices. Programs are at the box (high-level function) and system level. At the system level initial effort has been concentrated on specifying the tools needed to evaluate design alternatives.

Slotnick, D. L.↗

Infrared technology for satellite power conversion

Successful fabrication of bismuth bolometers led to the observation of antenna action rom array elements. Fabrication of the best antennas arrays was made more facile with finding that increased argon flow during the dc sputtering produced more uniform bismuth films and bonding to antennas must be done with the substrate temperaure below 100 C. Higher temperatures damaged the bolometers. During the testing of the antennas, it was found that the use of a quasi-optical system provided a uniform radiation field. Groups of antennas were bonded in series and in parallel with the parallel configuration showing the greater response.

Campbell, D. P.↗

Frequency Domain Control Design of Large Space Structures: A Practical Approach

Requirements indicate the need for much larger, more accurate, and in some cases, very dynamic satellites. Large control system bandwidths are needed to meet accuracy and response requirements while maintaining tight control over appendage oscillations. Studies in recent years have shown that linear quadratic Gaussian (LQG) controllers can achieve the desired performance if the system is linearized and if the system model is accurate. Results of an LQG controller applied to a single axis satellite with large solar arrays, are given. A reduced order model (ROM) comprises rigid body motion with dominant structural modes. Optimal control and estimation gains are calculated based on an extremely conservative 0.0005 critical damping ratio. In order to examine stability characteristics, single-input single-output (SISO) frequency response concepts are generalized to develop a method of displaying open loop frequency response of multi-input multi-output (MIMO) control system.

Harding, R.↗

A star camera aspect system suitable for use in balloon experiments

A balloon-borne experiment containing a star camera aspect system was designed, built, and flown. This system was designed to provide offset corrections to the magnetometer and inclinometer readings used to control an azimuth and elevation pointed experiment. The camera is controlled by a microprocessor, including commendable exposure and noise rejection threshold, as well as formatting the data for telemetry to the ground. As a background program, the microprocessor runs the aspect program to analyze a fraction of the pictures taken so that aspect information and offset corrections are available to the experiment in near real time. The analysis consists of pattern recognition of the star field with a star catalog in ROM memory and a least squares calculation. The performance of this system in ground based tests is described. It is part of the NASA/GSFC High Energy Gamma-Ray Balloon Instrument (2).

Hunter, S. D.↗

Digital Signal Combining for Conference Calling

Signals combined with minimal noise by use of sums in read-only memories. Signals from subscribers A and B digitized, transmitted, and combined by addressing ROM. Combining operation electronic equivalent of looking up value of function of two variables in mathematical table. Combined digitized signal transmitted, converted to analog form, and delivered to subscriber C. System intended especially for combining number of separate audio signals into one signal for retransmission, as in telephone conference calling.

Byrne, F.↗

Annual and Semiannual Cycles Based on the Middle Atmosphere Reference Model

The SCR/PMR monthly temperature mean values were Fourier analysed at each latitude and pressure level to obtain the annual mean and the amplitude and phase of the annual and semiannual cycles. The phase is the month of the maximum, such that 1 = January 1, 1.5 = January 16, 2 = February 1, etc. Some very marked hemispheric differences noted are: (1) at 80 N there is a maximum amplitude of the annual cycle of 26 K at 2.5 mb, the corresponding maximum at 80 S is much stronger (35 K) and at a lower altitude (11 mb); (2) the semiannual amplitudes show the well known maximum over the tropics in the upper stratosphere, but also maxima at high latitudes; and (3) the annual mean shows a minimum at 50 S, 1 mb, and a corresponding weaker minimum at 60 N. In general, the hemispheres are remarkably similar and six months out of phase above about 0.3 mb (56 km). The two hemispheres are significantly different especially in winter after allowing for a six month shift. Changes rom summer to winter are so large by comparison that the annual cycles appear to be very similar.

Barnett, J. J.↗

Assessing the proficiency of software developers

The trend lines presented can be useful in a number of ways. They provide a baseline of comparision from which software developers can compare their performance against a large database of similar projects. This will often identify a organizational style. It was possible to quantify the organizational style using the Manpower Buildup Gradient. That the developer was a better than average producer on RAM based systems was shown. The Ck associated with the ROM system suggests that it is a different class of work. When this system is compared against the Firmware database it is very creditable. It is important to recognize that there are non linearities present in the software process. The non linearities are tied to system size. For comparative purposes one must always make judgements based on similar sizes. In the past the tendency has been to calculate a few ratios on several projects and then compare them without any regard to amount of functionality that was created. This practice can be very misleading and dangerous. The method described, used in a thoughtful analytic manner, can be very helpful.

Putnam, L. H.↗

CCD Memory

CCD memory device yields over 6.4 x 10 to the eighth power levels of information on single chip. Charge-coupled device (CCD) demonstrated to operate as either read-only-memory (ROM) or photon-programmable memory with capacity of 640,000 bits, with each bit capable of being weighted to more than 1,000 discrete analog levels. Larger memory capacities now possible using proposed approach in conjunction with CCD's now being fabricated, which yield over 4 x 10 to the ninth power discrete levels of information on single chip.

Janesick, James R.↗

The status of the international Halley watch

More than 1000 professional astronomers worldwide actually observed Halley's comet from the ground. Preliminary logs from the observers indicate that 20-40 Gbytes of data were acquired in eight professional disciplines and as much as 5 Gbytes in the amateur network. The latter will be used to fill in gaps in the Archive and to provide a visual light curve. In addition roughly 400 Mbytes of data were taken on Comet Giacobini-Zinner. Data will be accepted for archiving until early 1989. The permanent archive will consist of a set of CD-ROMs and a set of books, publication of both to be completed by mid-1990. Data from the space missions will be included but only on the CDs. From every indication, the ground based effort and the space missions complimented each other beautifully, both directly in the solution of spacecraft navigation problems and indirectly in the solution of scientific problems. The major remaining concern is that scientists submit their data to the Archive before the 1989 deadline.

Newburn, Ray L., Jr.↗

Digital cartography of the planets - New methods, its status, and its future

A system has been developed that establishes a standardized cartographic database for each of the 19 planets and major satellites that have been explored to date. Compilation of the databases involves both traditional and newly developed digital image processing and mosaicking techniques, including radiometric and geometric corrections of the images. Each database, or digital image model (DIM), is a digital mosaic of spacecraft images that have been radiometrically and geometrically corrected and photometrically modeled. During compilation, ancillary data files such as radiometric calibrations and refined photometric values for all camera lens and filter combinations and refined camera-orientation matrices for all images used in the mapping are produced. The system is designed to aid in the following: access to and utilization of spatial data returned by planetary spacecraft; coregistration of cartographic image and topographic elevation models with geological, geophysical, and geochemical databases; and the design and preparation of both standard and custom map products. A major goal of the project is to publish the DIMs on compact computer-compatible media such as digital-optical (CD-ROM) disks.

Batson, R. M.↗

A proposed Applications Information System - Concept, implementation, and growth

This paper describes a newly developed concept within NASA for an Applications Information System (AIS). The AIS would provide the opportunity to the public and private sectors of shared participation in a remote sensing research program directed to a particular set of land-use or environmental problems. Towards this end, the AIS would offer the technological framework and information system resources to overcome many of the deficiencies that end-users have faced over the years such as limited access to data, delay in data delivery, and a limited access to data reduction algorithms and models to convert data to geophysical measurements. In addition, the AIS will take advantage of NASA developments in networking among information systems and use of state of the art technology, such as CD Roms and optical disks for the purpose of increasing the scientific benefits of applied environmental research. The rationale for the establishment of an AIS, a methodology for a step-wise, modular implementation, and the relationship of the AIS to other NASA information systems are discussed.

Mcconnell, Dudley G.↗

Current status of the international Halley Watch infrared net archive

The primary purposes of the Halley Watch have been to promote Halley observations, coordinate and standardize the observing where useful, and to archive the results in a database readily accessible to cometary scientists. The intention of IHW is to store the observations themselves, along with any information necessary to allow users to understand and use the data, but to exclude interpretations of these data. Each of the archives produced by the IHW will appear in two versions: a printed archive and a digital archive on CD-ROMs. The archive is expected to have a very long lifetime. The IHW has already produced an archive for P/Crommelin. This consists of one printed volume and two 1600 bpi tapes. The Halley archive will contain at least twenty gigabytes of information.

Mcguinness, Brian B.↗

Proceedings of the Goddard Space Flight Center Workshop on Robotics for Commercial Microelectronic Processes in Space

Potential applications of robots for cost effective commercial microelectronic processes in space were studied and the associated robotic requirements were defined. Potential space application areas include advanced materials processing, bulk crystal growth, and epitaxial thin film growth and related processes. All possible automation of these processes was considered, along with energy and environmental requirements. Aspects of robot capabilities considered include system intelligence, ROM requirements, kinematic and dynamic specifications, sensor design and configuration, flexibility and maintainability. Support elements discussed included facilities, logistics, ground support, launch and recovery, and management systems.

Source record↗

Revolutionary opportunities for materials and structures study, addendum

This report is an addendum to the Revolutionary Opportunities for Materials and Structures Study (ROMS), modifying the original by the addition of two tasks. The primary purpose of these tasks was to conduct additional aircraft/engine sizing and mission analysis to obtain contributory aircraft performance data such as fuel burns and direct operating costs for both the subsonic and supersonic engines.

Feig, P. D.↗

General-Purpose Serial Interface For Remote Control

Computer controls remote television camera. General-purpose controller developed to serve as interface between host computer and pan/tilt/zoom/focus functions on series of automated video cameras. Interface port based on 8251 programmable communications-interface circuit configured for tristated outputs, and connects controller system to any host computer with RS-232 input/output (I/O) port. Accepts byte-coded data from host, compares them with prestored codes in read-only memory (ROM), and closes or opens appropriate switches. Six output ports control opening and closing of as many as 48 switches. Operator controls remote television camera by speaking commands, in system including general-purpose controller.

Busquets, Anthony M.↗

Investigation of the reaction kinetics between SiC fibers and selectively alloyed titanium matrix composites and determination of their mechanical properties

During high temperature exposure, an interfacial reaction occurs between SiC fiber reinforcement and titanium matrices which can be detrimental to the mechanical properties of the composite. The reaction kinetics between SCS-6 fibers and Ti-1100 were determined at 800 to 1000 C and found to be slower than those of other currently used titanium alloys (Ti-15-3, Ti-6-4). The experimentally determined reaction kinetics for Ti-1100 were extrapolated to 700 C and found to accurately predict reaction zone size after 1000 hours of exposure. Predictions of the time to consume the surface layer on the SCS-6 and SCS-9 fibers were made in an effort to estimate the time that the fiber will retain its strength in Ti-1100 during isothermal exposure at high temperatures. Using this approach, the strength of an SCS-6 fiber in Ti-1100 should be retained for over 20,000 hours at isothermal exposures less than 800 C. Strength predictions using the rule of mixtures for a unidirectional Ti-1100/SCS-6 composite are presented for short term exposures up to 700 C. Room temperature tests of an as-fabricated 20 volume percent fiber/Ti-1100 composite yielded a UTS of 226 ksi (1490 MPa) which is close to that predicted by the ROM.

Gundel, Douglas B.↗

Failure of the ERBE scanner instrument aboard NOAA 10 spacecraft and results of failure analysis

The Earth Radiation Budget Experiment (ERBE) scanner instrument on the NOAA 10 spacecraft malfunctioned on May 22, 1989, after more than 4 years of in-flight operation. After the failure, all instrument operational mode commands were tested and the resulting data analyzed. Details of the tests and analysis of output data are discussed therein. The radiometric and housekeeping data appear to be valid. However, the instrument will not correctly execute operational scan mode commands or the preprogrammed calibration sequences. The data indicate the problem is the result of a failure in the internal address decoding circuity in one of the ROM (read only memory) chips of the instrument computer.

Miller, J. B.↗

Displaying Images Of Planets

Interactive Image Display Program (IMDISP) is interactive image-displaying utility program for IBM personal computer (PC, XT, and AT models) and compatibles. Magnifications, contrasts, and/or subsampling selected for whole or partial images. IMDISP developed for use with CD-ROM (Compact Disk Read-Only Memory) storage system. Written in C language (94 percent) and Assembler (6 percent).

Martin, Michael D.↗