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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 595 records · Page 33

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NASA NTRS1982

Programming real-time executives in higher order language

Methods by which real-time executive programs can be implemented in a higher order language are discussed, using HAL/S and Path Pascal languages as program examples. Techniques are presented by which noncyclic tasks can readily be incorporated into the executive system. Situations are shown where the executive system can fail to meet its task scheduling and yet be able to recover either by rephasing the clock or stacking the information for later processing. The concept of deadline processing is shown to enable more effective mixing of time and information synchronized systems.

Foudriat, E. C.↗

NASA NTRS1988

Advanced control evaluation for structures (ACES) programs

The ACES programs are a series of past, present, and future activities at the Marshall Space Flight Center (MSFC) Ground facility for Large Space Structure Control Verification (GF/LSSCV). The main objectives of the ACES programs are to implement control techniques on a series of complex dynamical systems, to determine the control/structure interaction for the control techniques, and to provide a national facility in which dynamics and control verification can be effected. The focus is on these objectives and how they are implemented under various engineering and economic constraints. Future plans that will be effected in upcoming ACES programs are considered.

Pearson, Jerome↗

NASA NTRS2008

On the Application of a Response Surface Technique to Analyze Roll-over Stability of Capsules with Airbags Using LS-Dyna

As NASA moves towards developing technologies needed to implement its new Exploration program, studies conducted for Apollo in the 1960's to understand the rollover stability of capsules landing are being revisited. Although rigid body kinematics analyses of the roll-over behavior of capsules on impact provided critical insight to the Apollo problem, extensive ground test programs were also used. For the new Orion spacecraft being developed to implement today's Exploration program, new air-bag designs have improved sufficiently for NASA to consider their use to mitigate landing loads to ensure crew safety and to enable re-usability of the capsule. Simple kinematics models provide only limited understanding of the behavior of these air bag systems, and more sophisticated tools must be used. In particular, NASA and its contractors are using the LS-Dyna nonlinear simulation code for impact response predictions of the full Orion vehicle with air bags by leveraging the extensive air bag prediction work previously done by the automotive industry. However, even in today's computational environment, these analyses are still high-dimensional, time consuming, and computationally intensive. To alleviate the computational burden, this paper presents an approach that uses deterministic sampling techniques and an adaptive response surface method to not only use existing LS-Dyna solutions but also to interpolate from LS-Dyna solutions to predict the stability boundaries for a capsule on airbags. Results for the stability boundary in terms of impact velocities, capsule attitude, impact plane orientation, and impact surface friction are discussed.

Horta, Lucas G.↗

NASA NTRS2006

Programs for Testing Processor-in-Memory Computing Systems

The Multithreaded Microbenchmarks for Processor-In-Memory (PIM) Compilers, Simulators, and Hardware are computer programs arranged in a series for use in testing the performances of PIM computing systems, including compilers, simulators, and hardware. The programs at the beginning of the series test basic functionality; the programs at subsequent positions in the series test increasingly complex functionality. The programs are intended to be used while designing a PIM system, and can be used to verify that compilers, simulators, and hardware work correctly. The programs can also be used to enable designers of these system components to examine tradeoffs in implementation. Finally, these programs can be run on non-PIM hardware (either single-threaded or multithreaded) using the POSIX pthreads standard to verify that the benchmarks themselves operate correctly. [POSIX (Portable Operating System Interface for UNIX) is a set of standards that define how programs and operating systems interact with each other. pthreads is a library of pre-emptive thread routines that comply with one of the POSIX standards.]

Katz, Daniel S.↗

NASA NTRS2006

Array-Pattern-Match Compiler for Opportunistic Data Analysis

A computer program has been written to facilitate real-time sifting of scientific data as they are acquired to find data patterns deemed to warrant further analysis. The patterns in question are of a type denoted array patterns, which are specified by nested parenthetical expressions. [One example of an array pattern is ((>3) 0 (not=1)): this pattern matches a vector of at least three elements, the first of which exceeds 3, the second of which is 0, and the third of which does not equal 1.] This program accepts a high-level description of a static array pattern and compiles a highly optimal and compact other program to determine whether any given instance of any data array matches that pattern. The compiler implemented by this program is independent of the target language, so that as new languages are used to write code that processes scientific data, they can easily be adapted to this compiler. This program runs on a variety of different computing platforms. It must be run in conjunction with any one of a number of Lisp compilers that are available commercially or as shareware.

James, Mark↗

NASA NTRS1987

Color postprocessing for 3-dimensional finite element mesh quality evaluation and evolving graphical workstation

Three general tasks on general-purpose, interactive color graphics postprocessing for three-dimensional computational mechanics were accomplished. First, the existing program (POSTPRO3D) is ported to a high-resolution device. In the course of this transfer, numerous enhancements are implemented in the program. The performance of the hardware was evaluated from the point of view of engineering postprocessing, and the characteristics of future hardware were discussed. Second, interactive graphical tools implemented to facilitate qualitative mesh evaluation from a single analysis. The literature was surveyed and a bibliography compiled. Qualitative mesh sensors were examined, and the use of two-dimensional plots of unaveraged responses on the surface of three-dimensional continua was emphasized in an interactive color raster graphics environment. Finally, a postprocessing environment was designed for state-of-the-art workstation technology. Modularity, personalization of the environment, integration of the engineering design processes, and the development and use of high-level graphics tools are some of the features of the intended environment.

Panthaki, Malcolm J.↗

NASA NTRS1972

Nonlinear and Digital Man-machine Control Systems Modeling

An adaptive modeling technique is examined by which controllers can be synthesized to provide corrective dynamics to a human operator's mathematical model in closed loop control systems. The technique utilizes a class of Liapunov functions formulated for this purpose, Liapunov's stability criterion and a model-reference system configuration. The Liapunov function is formulated to posses variable characteristics to take into consideration the identification dynamics. The time derivative of the Liapunov function generate the identification and control laws for the mathematical model system. These laws permit the realization of a controller which updates the human operator's mathematical model parameters so that model and human operator produce the same response when subjected to the same stimulus. A very useful feature is the development of a digital computer program which is easily implemented and modified concurrent with experimentation. The program permits the modeling process to interact with the experimentation process in a mutually beneficial way.

Mekel, R.↗

NASA NTRS1987

Implementation of a research prototype onboard fault monitoring and diagnosis system

Due to the dynamic and complex nature of in-flight fault monitoring and diagnosis, a research effort was undertaken at NASA Langley Research Center to investigate the application of artificial intelligence techniques for improved situational awareness. Under this research effort, concepts were developed and a software architecture was designed to address the complexities of onboard monitoring and diagnosis. This paper describes the implementation of these concepts in a computer program called FaultFinder. The implementation of the monitoring, diagnosis, and interface functions as separate modules is discussed, as well as the blackboard designed for the communication of these modules. Some related issues concerning the future installation of FaultFinder in an aircraft are also discussed.

Palmer, Michael T.↗

NASA NTRS1987

Simulation Of The Internal-Combustion Engine

Program adapts to available information about particular engine. Mathematical model of internal-combustion engine constructed and implemented as computer program suitable for use on large digital computer systems. ZMOTTO program calculates Otto-cycle performance parameters as well as working-fluid compositions and properties throughout cycle for number of consecutive cycles and for variety of input parameters. Written in standard FORTRAN IV.

Zeleznik, Frank J.↗

NASA NTRS1997

Dryden Flight Research Center Chemical Pharmacy Program

The Dryden Flight Research Center (DFRC) Chemical Pharmacy "Crib" is a chemical sharing system which loans chemicals to users, rather than issuing them or having each individual organization or group purchasing the chemicals. This cooperative system of sharing chemicals eliminates multiple ownership of the same chemicals and also eliminates stockpiles. Chemical management duties are eliminated for each of the participating organizations. The chemical storage issues, hazards and responsibilities are eliminated. The system also ensures safe storage of chemicals and proper disposal practices. The purpose of this program is to reduce the total releases and transfers of toxic chemicals. The initial cost of the program to DFRC was $585,000. A savings of $69,000 per year has been estimated for the Center. This savings includes the reduced costs in purchasing, disposal and chemical inventory/storage responsibilities. DFRC has chemicals stored in 47 buildings and at 289 locations. When the program is fully implemented throughout the Center, there will be three chemical locations at this facility. The benefits of this program are the elimination of chemical management duties; elimination of the hazard associated with chemical storage; elimination of stockpiles; assurance of safe storage; assurance of proper disposal practices; assurance of a safer workplace; and more accurate emissions reports.

Davis, Bette↗

NASA NTRS2018

Digital Proxy Simulation of Robotic Hardware

A computer-implemented method, computer program product, and computing system is provided for a digital proxy simulation of robotic hardware. In an implementation, a method may include creating a digital proxy simulation for a robotic hardware wherein the digital simulation and the robotic hardware may share a network interface. a user may be provided with an option to switch between the robotic hardware and the digital proxy simulation. The switch may be executed, upon receiving a user selection, between the robotic hardware and the digital proxy simulation, wherein executing the switch includes transferring input and output signals between the digital proxy simulation and the robotic hardware.

Bacon, James A.↗

NASA NTRS2024

Implementation of a First-Order Quadratic Program Solver in C

This paper details a translation of a first order quadratic program (QP) solver from MATLAB to C. NASA could use this QP solver to generate online flight path trajectories for powered descent vehicles during landing. Over 12 weeks, the team designed, implemented, and tested two iterations of the QP solver for accuracy and runtime on 104 benchmark QP tests. The final iteration was 541.07% faster than the first, handling most tests in under one second. Additionally, it solved four more QP tests for N≥1383, and all outputs for cost and D_x matched the MATLAB reference values.

Optimization↗

NASA NTRS2010

Computation of Earth Science Products on Spaceborne Platforms

Spaceborne sensors like NASA's Hyperion hyperspectral imager generate huge data volumes, and several near-term trends indicate that data volumes will only increase. Next-generation hyperspectral missions, such as NASA's Hyperspectral Infrared Imager (HyspIRI), will operate at higher duty cycles and higher data rates, and their users will expect products to be generated from the data in near real time [1]. Barring a sudden advance in satellite downlink capacity, these trends point to a need to process data and generate products onboard the spacecraft. Rather than downlink an entire hyperspectral image cube, onboard processing enables satellites to downlink partial or completed scientific data products, which are often one to two orders of magnitude smaller than the original image. In addition, a satellite with onboard data processing resources and direct broadcast transmission equipment could send data products directly to first responders, research scientists or other users on the ground. Next-generation space-capable data processors will have a combination of reconfigurable gate arrays, digital signal processors and general-purpose CPUs. Correctly programmed and configured, these resources are sufficient to run sophisticated data analysis programs, including hyperspectral image processing algorithms that commonly run on desktop computers [2]. This paper describes how we implemented one such program, the HSEG hierarchical image segmentation algorithm, software commonly used on desktop and parallel processors, on a hardware platform designed to mimic a next-generation space-capable data processor [3]. We also describe our approach to porting the algorithm to and optimizing it for the new platform, and determine the expected performance gains enabled by our design. This extended abstract will describe the HSEG algorithm and hardware platform in greater detail, provide an analysis of the key function within the algorithm that required hardware acceleration, and describe our implementation of that function in hardware.

Fisher, Kevin↗

NASA NTRS1987

Optoelectronic analogs of self-programming neural nets - Architecture and methodologies for implementing fast stochastic learning by simulated annealing

Self-organization and learning is a distinctive feature of neural nets and processors that sets them apart from conventional approaches to signal processing. It leads to self-programmability which alleviates the problem of programming complexity in artificial neural nets. In this paper architectures for partitioning an optoelectronic analog of a neural net into distinct layers with prescribed interconnectivity pattern to enable stochastic learning by simulated annealing in the context of a Boltzmann machine are presented. Stochastic learning is of interest because of its relevance to the role of noise in biological neural nets. Practical considerations and methodologies for appreciably accelerating stochastic learning in such a multilayered net are described. These include the use of parallel optical computing of the global energy of the net, the use of fast nonvolatile programmable spatial light modulators to realize fast plasticity, optical generation of random number arrays, and an adaptive noisy thresholding scheme that also makes stochastic learning more biologically plausible. The findings reported predict optoelectronic chips that can be used in the realization of optical learning machines.

Farhat, Nabil H.↗

NASA NTRS1973

Measurement of high altitude air quality using aircraft

The minor atmospheric constituents associated with and affected by aircraft exhaust emissions at altitudes from 6 to 20 km will be monitored in flight programs presently being implemented. Preliminary in situ data are available from flight tests of dedicated instruments to be used in these programs. A Global Atmospheric Sampling Program using Boeing 747 airliners was determined to be feasible in studies conducted by airlines and airframe companies. Worldwide monitoring in the troposphere and the lower stratosphere is planned. Stratospheric air sampling on a more local basis will be done with a U2 aircraft. Measuring system evaluations and improvements have been required to detect the low background levels.

Rudey, R. A.↗

NASA NTRS1973

Measurement of high-altitude air quality using aircraft.

Rudey, R. A.↗

NASA NTRS1975

Evaluation of the electrochemical O2 concentrator as an O2 compressor

A program was successfully completed to analytically and experimentally evaluate the feasibility of using an electrochemical oxygen (O2) concentrator as an O2 compressor. The electrochemical O2 compressor (EOC) compresses 345 kN/sq m (50 psia) O2 generated on board the space vehicle by the water electrolysis subsystem (WES) in a single stage to 20,700 kN/sq m (3000 psia) to refill spent extravehicular equipment O2 bottles and to eliminate the need for high pressure O2 storage. The single cell EOC designed, fabricated, and used for the feasibility testing is capable of being tested at O2 pressures up to 41,400 kN/sq m (6000 psia). A ground support test facility to test the EOC cell was designed, fabricated, and used for the EOC feasibility testing. A product assurance program was established, implemented, and maintained which emphasized safety and materials compatibility associated with high pressure O2 operation. A membrane development program was conducted to develop a membrane for EOC application. Data obtained using a commercially available membrane were used to guide the development of the membranes fabricated specifically for an EOC. A total of 15 membranes were fabricated.

Marshall, R. D.↗

NASA NTRS1983

The SIFT Code Specification

The specification of Software Implemented Fault Tolerance (SIFT) consists of two parts, the specifications of the SIFT models and the specifications of the SIFT PASCAL program which actually implements the SIFT system. The code specifications are the last of a hierarchy of models describing the operation of the SIFT system and are related to the SIFT models as well as the PASCAL program. These Specifications serve to link the SIFT models to the running program. The specifications are very large and detailed and closely follow the form and organization of the PASCAL code. In addition to describing each of the components of the SIFT code, the code specifications describe the assumptions of the upper SIFT models which are required to actually prove that the code will work as specified. These constraints are imposed primarily on the schedule tables.

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