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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 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Indoor test for thermal performance evaluation of seven Elcam fin-tube solar collector configurations

The test procedure used and the results obtained from an evaluation test program conducted to obtain thermal performance data on seven Elcam fin-tube solar collector configurations under simulated conditions are described. These tests were made using the Marshall Space Flight Center solar facilities. The Elcam fin-tube (liquid) solar collectors each consist of an absorber plate 5.9 inches wide by 83 inches long and a type M copper tube of 0.569 inch nominal inside diameter. No cover plate was used with any of the specimens. The uniqueness of each of the seven configurations is described, and tests were performed on each separate configuration.

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NASA NTRS1993

On the performance of Trellis coded modulation with octal phase shift keying over the TDRSS channel

As the National Aeronautics and Space Administration moves into the 21st century with programs like Space Station Freedom, a manned mission to Mars, and the new Landsat mission, transmission demands on the Tracking and Data Relay Satellite System (TDRSS) will very likely exceed the available bandwidth. The Manual Lujan, Jr. Center for Space Telemetering and Telecommunications Systems (CSTTS) at New Mexico State University (NMSU) is studying techniques for increasing the data rate capabilities of TDRSS. These techniques include the use of advanced bandwidth efficient modulation formats to increase the data rate that can be sustained in a TDRSS transponder and the use of lossless bandwidth compression of the data to be transmitted to lower the data rate required from the user spacecraft. Based upon current technology the most promising bandwidth efficient modulation technique is Trellis Coded Modulation (TCM) operating with Octal Phase shift Keying (8PSK). Trellis Coded Modulation coding with 8PSK carrier modulation has the capability to increase the data rate which can be transmitted through the TDRSS spacecraft by a factor of 2 to 2.5 times that available with todays coded QPSK systems with only a small penalty in link performance relative to the existing systems. However, before NASA can safely employ TCM coding it is necessary to prove that this complex format can perform on the real TDRSS link as it does in labs and simulation studies. This proof-of-concept test over a live satellite channel was the objective of the construction and testing performed under this task of the NMSU NASA grant referenced above. In conjunction with NASA, NMSU's CSTTS has constructed a system to test a new candidate TDRSS modulation scheme, TCM 8PSK, that can enhance the information throughput of the TDRSS spacecraft. The test system for this project which was constructed over a period of 18 months by NMSU consisted of two racks of commercial and univeristy-designed and -built equipment. This project has included modifications of an existing White Sands Ground Terminal (WSGT) High Rate QPSK Demodulator to demodulate 8PSK as well as the construction of other support hardware. Also, two TCM codecs (coder/decoders) have been constructed to implement two levels of bandwidth efficiency. One was designed and built by the research team at NMSU while the other was created by the University of Notre Dame with the University of South Australia. The NMSU codec achieves a 2-to-1 increase in data rate per unit bandwidth with a coding gain relative to QPSK of about 3dB. The Notre Dame/South Australia codec achieves a 2.5-to-1 increase in data rate per unit of occupied bandwidth and a coding gain of about 2dB.

Osborne, William P.↗
NASA NTRS2021

Integration of an Arm Kinematics Hot Patch onboard the Curiosity Rover

NASA's Mars Science Laboratory (MSL) mission has updated the Curiosity rover's flight software multiple times since landing on Mars on August 6, 2012. The most common patching method has been a hot patch, in which running flight software is modified after being copied into RAM from its persistent storage. The latest hot patch to be installed on Curiosity fixed an issue in the robotic arm software that computes generalized inverse kinematics. Additional unit testing performed since the start of the surface mission revealed that this software can sometimes produce erroneous solutions.The cause was identified as numerical instability in a quartic root finder. When the inputs to that solver are not well conditioned, floating-point numerical issuescan cause erroneous roots to be reported. In theory, this could result in the robotic arm turret instruments being commanded to unintended positions, for example, below the terrain surface. Out of approximately 3.7 million unit test cases, 97.2\% of the position errors were below 5 mm. However, there were 16 test cases where theposition error was greater than 20 cm, and the maximum position error was 1.2 meters.The patch was uploaded to Curiosity on sol 2642 (January 11, 2020) after the solution was developed, re-implemented as a hot patch, and validated and verified using Earth-based Curiosity testbeds. A checkout test of the patch was performed on Curiosity on sol 2657, and nominal use of the patch began on sol 2658. In this paper, we describe the steps that led to integrating the arm kinematic hot patch into Curiosity's flight software, from the discovery of the bug to the nominal use of the patch in flight.

Maimone, Mark↗
DOE OSTI2018

Lifetime laser damage performance of β-Ga 2 O 3 for high power applications

Gallium oxide (Ga 2 O 3 ) is an emerging wide bandgap semiconductor with potential applications in power electronics and high power optical systems where gallium nitride and silicon carbide have already demonstrated unique advantages compared to gallium arsenide and silicon-based devices. Establishing the stability and breakdown conditions of these next-generation materials is critical to assessing their potential performance in devices subjected to large electric fields. Here, by using systematic laser damage performance tests, we establish that β-Ga 2 O 3 has the highest lifetime optical damage performance of any conductive material measured to date, above 10 J/cm2 (1.4 GW/cm2). This has direct implications for its use as an active component in high power laser systems and may give insight into its utility for high-power switching applications. Both heteroepitaxial and bulk β-Ga 2 O 3 samples were benchmarked against a heteroepitaxial gallium nitride sample, revealing an order of magnitude higher optical lifetime damage threshold for β-Ga 2 O 3 . Photoluminescence and Raman spectroscopy results suggest that the exceptional damage performance of β-Ga 2 O 3 is due to lower absorptive defect concentrations and reduced epitaxial stress.

36 MATERIALS SCIENCE↗
DOE OSTI2017

PLATO (Parallel Load Assignment Tool): A Parallel Workload Partitioner for Particle-based Methods

A key first step in many large-scale high-performance scientific computing applications is the distribution of the computational domain across all participating processors of a parallel computing platform such as a shared memory machine, cluster or a tightly-coupled supercomputer. The primary goal of such a partitioning step is to ensure that the computational work performed by each process remains load-balanced throughout the execution of the parallel application. In this project, a general-purpose parallel partitioning tool, code-named PLATO, was designed and implemented. PLATO assumes that the workload is a set of points in an n-dimensional metric space. These points are abstractions of computational units that may represent point-like computational units such as celestial objects in astrophysics, atoms in materials sciences and molecules in biology/chemistry, or may represent more abstract computational units such as grid points in finite difference methods, grid elements in finite element methods or n-dimensional points in the feature space of a host of other applications. PLATO supports several key and useful capabilities, namely: (a) multiple load partitioning strategies, (b) support for arbitrary user-defined processor topology, (c) pre-fetching data from neighboring processors based on user-defined parameters, and (d) support for arbitrary number and types of attributes associated with each point in the computational domain. PLATO is implemented in the C programming language using Message Passing Interface (MPI) for inter-processor communications and its parallel performance tested on up to 48 processors of a shared memory machine. This report includes a detailed performance study of PLATO using parallel speedup and iso-efficiency as the two main metrics of parallel performance. In addition, a user manual and DOXYGEN generated code documentation have been included for completeness.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

DOE Residential Energy Code Field Study - Pennsylvania

This project consisted of three distinct phases – all focused on residential one- and two-family dwellings and townhouses. Phase 1 included a baseline field study with inspections and performance testing to assess construction practices with respect to the energy code. PNNL used the data to perform EUI and savings potential analyses. Phase 2 consisted of training, education, and outreach to building industry professionals with content based on the findings from Phase 1. Phase 3 was a post-program field study using the same methodology as Phase 1 and was intended to measure the impact of Phase 2. During Phase 1 of the project, PSD collected data from 171 job sites across eastern Pennsylvania, a territory bounded by PECO, PPL, and Met-Ed electric distribution territories, to reach the required 63 “home equivalents” deemed necessary by PNNL for a representative sample. Based on subsequent analysis, four key items were identified as having significant savings potential from improvement in compliance, including duct leakage, above-grade wall insulation (specifically insulation installation quality), foundation insulation, and high-efficacy lighting. About half the total savings potential is from duct leakage, so that was the primary focus. The goal of Phase 2 was to improve upon these key compliance weaknesses through an intensive training, education, and outreach program. PSD dubbed this effort the Penn Energy Codes Program. For Phase 3, PSD obtained a new sample plan from PNNL, obtained permit data from sample municipalities, and made substitutions where necessary. PSD field staff visited 165 job sites to collect the required 504 key observations. PSD submitted all data collection sheets to PNNL for their analysis to determine if there was a measurable change due to Phase 2 activities.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Cooperative Research and Development Agreement between National Energy Technology Laboratory and Electric Power Research Institute (EPRI) [Abstract]

Carbon dioxide (CO 2 ) capture from flue gas generated by fossil fuel-fired power plants has been proposed as an efficient approach to limit CO 2 emissions to the atmosphere. Due to the high cyclic CO 2 sorption capacity, well-tuned adsorption chemistry and non-volatility, solid sorbents are widely studied for CO 2 capture processes such as pressure swing adsorption (PSA) and temperature swing adsorption (TSA). Realistic applications of traditional solid sorbent systems face many challenges since moisture and heat management are problematic and solid-solid heat exchange is inefficient. Recently, a novel solid sorbent system, the sorbent polymer composite (SPC), has been developed to overcome those challenges in an energy-saving CO 2 capture process using TSA membrane contactors. A SPC material is comprised of a powdered solid sorbent embedded into a hydrophobic and porous polymer matrix. It allows gases to permeate through and achieve full contact with the sorbents while rejecting water moisture in the CO 2 capture process. In this collaborative research, NETL will conduct performance testing of a novel SPC material and EPRI will conduct a cost analysis based on that performance data.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS1972

End-to-end RMS error testing on a constant bandwidth FM/FM system

End-to-end root-mean-square (rms) tests performed on a constant bandwidth FM/FM system with various settings of system parameters are reported. The testing technique employed is that of sampling, digitizing, delaying, and comparing the analog input against the sampled and digitized corresponding output. Total system error is determined by fully loading all channels with band-limited noise and conducting end-to-end rms error tests on one channel. Tests are also conducted with and without a transmission link and plots of rms errors versus receiver signal-to-noise (S/N) values are obtained. The combined effects of intermodulation, adjacent channel crosstalk, and residual system noise are determined as well as the single channel distortion of the system.

Wallace, G. R.↗
NASA NTRS1974

Design, fabrication, and operation of a test rig for high-speed tapered-roller bearings

A tapered-roller bearing test machine was designed, fabricated and successfully operated at speeds to 20,000 rpm. Infinitely variable radial loads to 26,690 N (6,000 lbs.) and thrust loads to 53,380 N (12,000 lbs.) can be applied to test bearings. The machine instrumentation proved to have the accuracy and reliability required for parametric bearing performance testing and has the capability of monitoring all programmed test parameters at continuous operation during life testing. This system automatically shuts down a test if any important test parameter deviates from the programmed conditions, or if a bearing failure occurs. A lubrication system was developed as an integral part of the machine, capable of lubricating test bearings by external jets and by means of passages feeding through the spindle and bearing rings into the critical internal bearing surfaces. In addition, provisions were made for controlled oil cooling of inner and outer rings to effect the type of bearing thermal management that is required when testing at high speeds.

Signer, H. R.↗
NASA NTRS1975

Digital control of high-intensity acoustic testing

To eliminate previous system instabilities and control high-intensity acoustic tests, a digital control vibration test system is modified by a software change. Three systems for the control of acoustic testing are compared: a hybrid digital/analog system, a digital vibration system, and the same digital vibration system modified by a software change to allow acoustic testing. It is shown that the hybrid system and the modified vibration system exhibit almost equal performance, although the hybrid system performs testing twice as fast. The development of a specialized acoustic test control system is justified since it costs far less than the general-purpose vibration control system. However, the latter is much easier to set up for a test, which is important in preventing overtesting of valuable spacecraft components.

Slusser, R. A.↗
NASA NTRS1988

The effect of simulated weightlessness on performance and mood

The performance results of the bedrest study at Ames were not what were expected. The Air Combat Maneuvering performance test was tested to assure its reliability. However, the results from this study show a continued increase in performance. One would assume that scores would become constant if not decrease by the first days of bedrest because an inverted position would affect performance. It is also interesting to observe that while the subject's moods deteriorated, their performance improved. Although the performance results were surprising, the mood results were as expected.

Rosenberg, Bonnie↗
NASA NTRS1989

The Space Station Photovoltaic Panels Plasma Interaction Test Program: Test plan and results

The Plasma Interaction Test performed on two space station solar array panels is addressed. This includes a discussion of the test requirements, test plan, experimental set-up, and test results. It was found that parasitic current collection was insignificant (0.3 percent of the solar array delivered power). The measured arcing threshold ranged from -210 to -457 V with respect to the plasma potential. Furthermore, the dynamic response of the panels showed the panel time constant to range between 1 and 5 microsec, and the panel capacitance to be between .01 and .02 microF.

Nahra, Henry K.↗
NASA NTRS1990

The Space Station photovoltaic panels plasma interaction test program - Test plan and results

The plasma Interaction Test performed on two space station solar array panels is addressed. This includes a discussion of the test requirements, test plan, experimental set-up, and test results. It was found that parasitic current collection was insignificant (0.3 percent of the solar array delivered power). The measured arcing threshold ranged from -210 to -457 V with respect to the plasma potential. Furthermore, the dynamic response of the panels showed the panel time constant to range between 1 and 5 microsec, and the panel capacitance to be between .01 and .02 microF.

Nahra, Henry K.↗
NASA NTRS2001

Testing of a Loop Heat Pipe with Two Evaporators and Two Condensers

Most existing Loop Heat Pipes (LHPs) consist of one single evaporator and one single condenser. LHPs with multiple evaporators will be very desirable for cooling multiple heat sources or a heat source with large thermal footprints. Extending the LHP technology to include multiple evaporators and multiple condensers faces some challenges, including the interaction between individual compensation chambers, operating temperature stability, and adaptability to rapid power and sink temperature transients. This paper describe extensive testing of an LHP with two evaporators and two condensers. Tests performed include start-up, power cycle, sink temperature cycle, reservoir temperature cycle, and capillary limit. Test results showed that the loop could operate successfully under various heat load and sink conditions. The loop operating temperature is a function of the total heat load, the heat load distribution between the two evaporators, and temperatures of the two condenser sinks. Under most conditions, only one reservoir contained two-phase fluid and the other reservoir was completely liquid filled. Moreover, control of the loop operating temperature could shift from one reservoir to the other as the test condition changed.

Ku, Jentung↗
NASA NTRS2001

Active Control of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers

The operating temperature of a loop heat pipe (LHP) with multiple evaporators is a function of the total heat load, heat load distribution among evaporators, condenser temperature and ambient temperature. Because of the many variables involved, the operating temperature also showed more hystereses than an LHP with a single evaporator. Tight temperature control can be achieved by controlling its compensation chamber (CC) temperatures at the desired set point. This paper describes a test program on active control of the operating temperature in an LHP with two evaporators and two condensers. Temperature control was achieved by heating one or both CC's. Tests performed included start-up, power cycle, sink temperature cycle, CC temperature cycle, and capillary limit. Test results show that, regardless one or two CC's were heated to the set point temperature, one of CC's was always flooded with liquid. The loop could operate successfully at the desired set point temperature under most conditions, including some fast transients. At low heat loads, however, the CC temperature could suddenly increase above the set point temperature, possibly due to a sudden change of the vapor content inside the evaporator core.

Ku, Jentung↗
NASA NTRS2005

Return to Flight Resource Reel 1 of 2

A video presentation detailing the tests performed on the Space Shuttle Discovery in preparation for its return to flight is shown. The tests include: 1) Reinforced Carbon-Carbon (RCC) Impact Test Article; 2) RCC Foam Impact Testing; 3) Thermal Protection System (TPS) Ice Impact Testing featuring Justin Kerr, Project Engineer; 4) Wing Leading Edge Wireless Sensors featuring Karl Kiefer, President and CEO of Invocon, and Kevin Champaigne of Invocon; 5) TPS Repair Testing KC-135 Zero-G Environment featuring Soichi Noguchi, Mission Specialist; 6) TPS Extravehicular Activity Tool Demonstration; 7) TPS Repair Testing Vacuum Glove box; 8) TPS Repair Testing Human Thermal Vacuum Chamber; 9) TPS Reentry Testing Atmospheric Reentry Materials and Structures Evaluation Facility; 10) TPS Alternative Repair Concept; 11) Lora Bailey Lead Engineer for EVA Tools; 12) Reinforced Carbon-Carbon ATK Thiokol Plug Repair Animation; 13) 3-Percent Model Build-Up; and 14) Wind Tunnel Testing RCC Aging Research Ballistic Testing.

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NASA NTRS2005

Return to Flight Resource Reel 2 of 2

A continuation of the tests performed on the Space Shuttle Discovery in preparation for its return to flight is presented. The tests include: 1) Shuttle Robot Arm Recertification; 2) Michael Hiltz Systems Group Leader; 3) Orbiter Boom Fabrication; 4) Orbiter Boom Final Development; 5) Gary Searle Manager of Orbiter Boom Sensor System (OBSS) Manufacturing and Assembly; 6) Orbiter Boom Qualification Unit; 7) STS-114 Crew Inspects Orbiter Boom at Kennedy Space Center; 8) Orbiter Boom Inspection of Thermal Protection System Animation; 9) External Tank Bipod Redesign; 10) External Tank Flange Redesign; 11) External Tank Bellows Redesign; 12) Shuttle Main Engine Testing and Delivery to Kennedy Space Center; 13) Ronnie Rigney Project Manager Space Shuttle Main Engine Program Office; 14) Gene Goldmman NASA Project Manager Space Shuttle Main Engine Project; 15) Mike Cosgrove Boeing-Rocketdyne Flow Manager; 16) Shuttle Rocket Booster Build-Up; 17) Ascent Imagery Improvements; and 18) STS-114 Flight Control Team and Mission Management Team.

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