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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 487 records · Page 27

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NASA NTRS1981

airborne data analysis/monitor system

An Airborne Data Analysis/Monitor System (ADAMS), a ROLM 1666 computer based system installed onboard test airplanes used during experimental testing is evaluated. In addition to the 1666 computer, the ADAMS hardware includes a DDC System 90 fixed head disk and a Miltape DD400 floppy disk. Boeing designed a DMA interface to the data acquisition system and an intelligent terminal to reduce system overhead and simplify operator commands. The ADAMS software includes RMX/RTOS and both ROLM FORTRAN and assembly language are used. The ADAMS provides real time displays that enable onboard test engineers to make rapid decisions about test conduct thus reducing the cost and time required to certify new model airplanes, and improved the quality of data derived from the test, leading to more rapid development of improvements resulting in quieter, safer, and more efficient airplanes. The availability of airborne data processing removes most of the weather and geographical restrictions imposed by telemetered flight test data systems. A data base is maintained to describe the airplane, the data acquisition system, the type of testing, and the conditions under which the test is performed.

Stephison, D. B.↗

NASA NTRS1982

The power spectral density of digital modulations transmitted over nonlinear channels

This paper examines by analytical methods the power spectral densities of digital modulations (in particular, staggered and unstaggered quadrature modulations) passed through band-limited nonlinear channels. Previously observed (by computer simulation or hardware measurement) behavior of such spectra with regard to the suppression or restoration of its sidelobes after passing through the nonlinearity is verified analytically. Several examples corresponding to specific quadrature modulations and filter-nonlinearity combinations are presented as illustrations of the general results.

Divsalar, D.↗

NASA NTRS1984

Laser furnace technology for zone refining

A carbon dioxide laser experiment facility is constructed to investigate the problems in using a laser beam to zone refine semiconductor and metal crystals. The hardware includes a computer to control scan mirrors and stepper motors to provide a variety of melt zone patterns. The equipment and its operating procedures are described.

Griner, D. B.↗

NASA NTRS1985

Advances and trends in structures and dynamics; Proceedings of the Symposium, Washington, DC, October 22-25, 1984

Among the topics discussed are developments in structural engineering hardware and software, computation for fracture mechanics, trends in numerical analysis and parallel algorithms, mechanics of materials, advances in finite element methods, composite materials and structures, determinations of random motion and dynamic response, optimization theory, automotive tire modeling methods and contact problems, the damping and control of aircraft structures, and advanced structural applications. Specific topics covered include structural design expert systems, the evaluation of finite element system architectures, systolic arrays for finite element analyses, nonlinear finite element computations, hierarchical boundary elements, adaptive substructuring techniques in elastoplastic finite element analyses, automatic tracking of crack propagation, a theory of rate-dependent plasticity, the torsional stability of nonlinear eccentric structures, a computation method for fluid-structure interaction, the seismic analysis of three-dimensional soil-structure interaction, a stress analysis for a composite sandwich panel, toughness criterion identification for unidirectional composite laminates, the modeling of submerged cable dynamics, and damping synthesis for flexible spacecraft structures.

Noor, A. K.↗

NASA NTRS1985

Space station data system analysis/architecture study. Task 2: Options development DR-5. Volume 1: Technology options

The second task in the Space Station Data System (SSDS) Analysis/Architecture Study is the development of an information base that will support the conduct of trade studies and provide sufficient data to make key design/programmatic decisions. This volume identifies the preferred options in the technology category and characterizes these options with respect to performance attributes, constraints, cost, and risk. The technology category includes advanced materials, processes, and techniques that can be used to enhance the implementation of SSDS design structures. The specific areas discussed are mass storage, including space and round on-line storage and off-line storage; man/machine interface; data processing hardware, including flight computers and advanced/fault tolerant computer architectures; and software, including data compression algorithms, on-board high level languages, and software tools. Also discussed are artificial intelligence applications and hard-wire communications.

Source record↗

NASA NTRS1987

Simulation evaluation of the control system command monitoring concept for the NASA V/STOL research aircraft (VSRA)

A control-system monitoring concept is described that has the potential of rapidly detecting computer command failures (hardware or software) in fly-by-wire control systems. The concept has been successfully tested on the NASA Vertical/Short Takeoff and Landing Research Aircraft (VSRA) in the Ames Research Center's Vertical Motion Simulator. The test was particularly stringent, since the VSRA is required to operate in a hazardous environment. The fidelity of the aircraft model used in the simulation was verified by flying both the simulated and actual aircraft in a precision hover task using specially designed targets.

Schroeder, J. A.↗

NASA NTRS1985

Lewis' enhanced laboratory for research into the fatigue and constitutive behavior of high temperature materials

Lewis Research Center's high temperature fatigue laboratory has undergone significant changes resulting in the addition of several new experimental capabilities. New materials testing systems have been installed enabling research to be conducted in multiaxial fatigue and deformation at high temperature, as well as cumulative creep-fatigue damage wherein the relative failure-life levels are widely separated. A key component of the new high-temperature fatigue and structures laboratory is a local, distributed computer system whose hardware and software architecture emphasizes a high degree of configurability, which in turn, enables the researcher to tailor a solution to the problem at hand.

Mcgaw, Michael A.↗

NASA NTRS1985

An additional study and implementation of tone calibrated technique of modulation

The Tone Calibrated Technique (TCT) was shown to be theoretically free from an error floor, and is only limited, in practice, by implementation constraints. The concept of the TCT transmission scheme along with a baseband implementation of a suitable demodulator is introduced. Two techniques for the generation of the TCT signal are considered: a Manchester source encoding scheme (MTCT) and a subcarrier based technique (STCT). The results are summarized for the TCT link computer simulation. The hardware implementation of the MTCT system is addressed and the digital signal processing design considerations involved in satisfying the modulator/demodulator requirements are outlined. The program findings are discussed and future direction are suggested based on conclusions made regarding the suitability of the TCT system for the transmission channel presently under consideration.

Rafferty, W.↗

NASA NTRS1989

A noncontacting scanning photoelectron emission technique for bonding surface cleanliness inspection

Molecular contamination of bonding surfaces can drastically affect the bond strength that can be achieved and therefore the structural integrity and reliability of the bonded part. The presence of thin contaminant films on bonding surfaces can result from inadequate or incomplete cleaning methods, from oxide growth during the time between cleaning (such as grit blasting) and bonding, or from failure to properly protect cleaned surfaces from oils, greases, fingerprints, release agents, or deposition of facility airborne molecules generated by adjacent manufacturing or processing operations. Required cleanliness levels for desired bond performance can be determined by testing to correlate bond strength with contaminant type and quantity, thereby establishing the degree of contamination that can be tolerated based on the strength that is needed. Once the maximum acceptable contaminant level is defined, a method is needed to quantitatively measure the contaminant level on the bonding surface prior to bonding to verify that the surface meets the established cleanliness requirement. A photoelectron emission technique for the nondestructive inspection of various bonding surfaces, both metallic and nonmetallic, to provide quantitative data on residual contaminant levels is described. The technique can be used to scan surfaces at speeds of at least 30 ft/min using a servo system to maintain required sensor to surface spacing. The fundamental operation of the photoelectron emission sensor system is explained and the automated scanning system and computer data acquisition hardware and software are described.

Gause, Raymond L.↗

NASA NTRS1991

Dynamic Analyses Including Joints Of Truss Structures

Method for mathematically modeling joints to assess influences of joints on dynamic response of truss structures developed in study. Only structures with low-frequency oscillations considered; only Coulomb friction and viscous damping included in analysis. Focus of effort to obtain finite-element mathematical models of joints exhibiting load-vs.-deflection behavior similar to measured load-vs.-deflection behavior of real joints. Experiments performed to determine stiffness and damping nonlinearities typical of joint hardware. Algorithm for computing coefficients of analytical joint models based on test data developed to enable study of linear and nonlinear effects of joints on global structural response. Besides intended application to large space structures, applications in nonaerospace community include ground-based antennas and earthquake-resistant steel-framed buildings.

Belvin, W. Keith↗

NASA NTRS1991

MDO can help resolve the designer's dilemma

Multidisciplinary design optimization (MDO) is presented as a rapidly growing body of methods, algorithms, and techniques that will provide a quantum jump in the effectiveness and efficiency of the quantitative side of design, and will turn that side into an environment in which the qualitative side can thrive. MDO borrows from CAD/CAM for graphic visualization of geometrical and numerical data, data base technology, and in computer software and hardware. Expected benefits from this methodology are a rational, mathematically consistent approach to hypersonic aircraft designs, designs pushed closer to the optimum, and a design process either shortened or leaving time available for different concepts to be explored.

Sobieszczanski-Sobieski, Jaroslaw↗

NASA NTRS1991

A B-ISDN-compatible modem/codec

Coded modulation techniques for development of a broadband integrated services digital network (B-ISDN)-compatible modem/codec are investigated. The selected baseband processor system must support transmission of 155.52 Mbit/s of data over an INTELSAT 72-MHz transponder. Performance objectives and fundamental system parameters, including channel symbol rate, code rate, and the modulation scheme are determined. From several candidate codes, a concatenated coding system consisting of a coded octal phase shift keying modulation as the inner code and a high rate Reed-Solomon as the outer code is selected and its bit error rate performance is analyzed by computer simulation. The hardware implementation of the decoder for the selected code is also described.

Hemmati, F.↗

NASA NTRS1992

Sub-band/transform compression of video sequences

The progress on compression of video sequences is discussed. The overall goal of the research was the development of data compression algorithms for high-definition television (HDTV) sequences, but most of our research is general enough to be applicable to much more general problems. We have concentrated on coding algorithms based on both sub-band and transform approaches. Two very fundamental issues arise in designing a sub-band coder. First, the form of the signal decomposition must be chosen to yield band-pass images with characteristics favorable to efficient coding. A second basic consideration, whether coding is to be done in two or three dimensions, is the form of the coders to be applied to each sub-band. Computational simplicity is of essence. We review the first portion of the year, during which we improved and extended some of the previous grant period's results. The pyramid nonrectangular sub-band coder limited to intra-frame application is discussed. Perhaps the most critical component of the sub-band structure is the design of bandsplitting filters. We apply very simple recursive filters, which operate at alternating levels on rectangularly sampled, and quincunx sampled images. We will also cover the techniques we have studied for the coding of the resulting bandpass signals. We discuss adaptive three-dimensional coding which takes advantage of the detection algorithm developed last year. To this point, all the work on this project has been done without the benefit of motion compensation (MC). Motion compensation is included in many proposed codecs, but adds significant computational burden and hardware expense. We have sought to find a lower-cost alternative featuring a simple adaptation to motion in the form of the codec. In sequences of high spatial detail and zooming or panning, it appears that MC will likely be necessary for the proposed quality and bit rates.

Sauer, Ken↗

NASA NTRS1992

Person-like intelligent systems architectures for robotic shared control and automated operations

An approach to rendering robotic systems as 'personlike' as possible to achieve needed capabilities is outlined. Human characteristics such as knowledge, motivation, know-how, performance, achievement and individual differences corresponding to propensities and abilities can be supplied, within limits, with computing software and hardware to robotic systems provided with sufficiently rich sensory configurations. Pushing these limits is the developmental path for more and more personlike robotic systems. The portions of the Person Concept that appear to be most directly relevant to this effort are described in the following topics: reality concepts (the state-of-affairs system and descriptive formats, behavior as intentional action, individual persons (person characteristics), social patterns of behavior (social practices), and boundary conditions (status maxims). Personlike robotic themes and considerations for a technical development plan are also discussed.

Erickson, Jon D.↗

NASA NTRS1994

Technology transfer of operator-in-the-loop simulation

The technology developed for operator-in-the-loop simulation in space teleoperation has been applied to Caterpillar's backhoe, wheel loader, and off-highway truck. On an SGI workstation, the simulation integrates computer modeling of kinematics and dynamics, real-time computational and visualization, and an interface with the operator through the operator's console. The console is interfaced with the workstation through an IBM-PC in which the operator's commands were digitized and sent through an RS-232 serial port. The simulation gave visual feedback adequate for the operator in the loop, with the camera's field of vision projected on a large screen in multiple view windows. The view control can emulate either stationary or moving cameras. This simulator created an innovative engineering design environment by integrating computer software and hardware with the human operator's interactions. The backhoe simulation has been adopted by Caterpillar in building a virtual reality tool for backhoe design.

Yae, K. H.↗

NASA NTRS1994

Flight test of takeoff performance monitoring system

The Takeoff Performance Monitoring System (TOPMS) is a computer software and hardware graphics system that visually displays current runway position, acceleration performance, engine status, and other situation advisory information to aid pilots in their decision to continue or to abort a takeoff. The system was developed at the Langley Research Center using the fixed-base Transport Systems Research Vehicle (TSRV) simulator. (The TSRV is a highly modified Boeing 737-100 research airplane.) Several versions of the TOPMS displays were evaluated on the TSRV B-737 simulator by more than 40 research, United States Air Force, airline and industry and pilots who rated the system satisfactory and recommended further development and testing. In this study, the TOPMS was flight tested on the TSRV. A total of 55 takeoff and 30 abort situations were investigated at 5 airfields. TOPMS displays were observed on the navigation display screen in the TSRV research flight deck during various nominal and off-nominal situations, including normal takeoffs; reduced-throttle takeoffs; induced-acceleration deficiencies; simulated-engine failures; and several gross-weight, runway-geometry, runway-surface, and ambient conditions. All tests were performed on dry runways. The TOPMS software executed accurately during the flight tests and the displays correctly depicted the various test conditions. Evaluation pilots found the displays easy to monitor and understand. The algorithm provides pretakeoff predictions of the nominal distances that are needed to accelerate the airplane to takeoff speed and to brake it to a stop; these predictions agreed reasonably well with corresponding values measured during several fully executed and aborted takeoffs. The TOPMS is operational and has been retained on the TSRV for general use and demonstration.

Middleton, David B.↗

NASA NTRS1994

David Florida Laboratory Thermal Vacuum Data Processing System

During 1991, the Space Simulation Facility conducted a survey to assess the requirements and analyze the merits for purchasing a new thermal vacuum data processing system for its facilities. A new, integrated, cost effective PC-based system was purchased which uses commercial off-the-shelf software for operation and control. This system can be easily reconfigured and allows its users to access a local area network. In addition, it provides superior performance compared to that of the former system which used an outdated mini-computer and peripheral hardware. This paper provides essential background on the old data processing system's features, capabilities, and the performance criteria that drove the genesis of its successor. This paper concludes with a detailed discussion of the thermal vacuum data processing system's components, features, and its important role in supporting our space-simulation environment and our capabilities for spacecraft testing. The new system was tested during the ANIK E spacecraft test, and was fully operational in November 1991.

Choueiry, Elie↗

NASA NTRS2000

Health Monitoring System Technology Assessments: Cost Benefits Analysis

The subject of sensor-based structural health monitoring is very diverse and encompasses a wide range of activities including initiatives and innovations involving the development of advanced sensor, signal processing, data analysis, and actuation and control technologies. In addition, it embraces the consideration of the availability of low-cost, high-quality contributing technologies, computational utilities, and hardware and software resources that enable the operational realization of robust health monitoring technologies. This report presents a detailed analysis of the cost benefit and other logistics and operational considerations associated with the implementation and utilization of sensor-based technologies for use in aerospace structure health monitoring. The scope of this volume is to assess the economic impact, from an end-user perspective, implementation health monitoring technologies on three structures. It specifically focuses on evaluating the impact on maintaining and supporting these structures with and without health monitoring capability.

Kent, Renee M.↗