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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 55 records · Page 3

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NASA NTRS1977

JAN transistor and diode characterization test program, JANTX diode 1N649-1

The data processing and calculation of statistical parameters was performed by the Tektronix computer system. The data acquired for easy vendor to vendor and date code to date code analysis are summarized. Each parameter is presented with test conditions, mean, standard deviation, lowest reading, 10% point (where 10% of all readings are equal to or less than the indicated reading), 90% point (where 90% of all readings are equal to or less than the indicated reading) and the highest reading.

Takeda, H.↗

NASA NTRS1984

18-percent efficient terrestrial silicon solar cells

Silicon solar cells are described which operate at energy conversion efficiencies in excess of 18 percent under standard terrestrial test conditions (AM1.5, 100 mW/sq cm, 28 C). These are believed to be the most efficient silicon cells reported to date. The high efficiency is a result of the combination of high open-circuit voltage due to the careful attention paid to passivation of the top surface of the cell; high fill factors due to the high open-circuit voltage and low parasitic resistance losses; and high short-circuit current due to the use of shallow diffusions, a low grid coverage, and an optimized double-layer antireflection coating.

Blakers, A. W.↗

NASA NTRS1984

Towards a 20 percent efficient silicon solar cell

A project is underway at the University of New South Wales aimed at producing a 20 percent efficient silicon solar cell. A prerequisite for obtaining such a significant increase in cell efficiency is the improvement of the open circuit voltage of these cells. Two techniques are described which have produced experimental devices with open circuit voltages of 690 mV or higher. These high voltage techniques have been combined with other high efficiency design features to produce silicon cells with independently measured energy conversion efficiencies in excess of 19 percent under standard terrestrial test conditions (direct beam AM1.5 spectrum, 100 mW/sq cm, 28 C).

Green, M. A.↗

NASA NTRS1984

High-efficiency silicon solar cells

Silicon solar cells are described which operate at energy conversion efficiencies independently measured at 18.7 percent under standard terrestrial test conditions (AM1.5, 100 mW/sq cm, 28 C). These are apparently the most efficient silicon cells fabricated to date. The high-efficiency results from a combination of high open-circuit voltage due to the careful attention paid to the passivation of the top surface of the cell, high fill factor due to the high open-circuit voltage and low parasitic resistance losses, and high short-circuit current density due to the use of shallow diffusions, a low grid coverage, and an optimized double layer antireflection coating.

Green, M. A.↗

NASA NTRS2000

Quadruple Lap Shear Processing Evaluation

The Thiokol, Science and Engineering Huntsville Operations (SEHO) Laboratory has previously experienced significant levels of variation in testing Quadruple Lap Shear (QLS) specimens. The QLS test is used at Thiokol / Utah for the qualification of Reusable Solid Rocket Motor (RSRM) nozzle flex bearing materials. A test was conducted to verify that process changes instituted by SEHO personnel effectively reduced variability, even with normal processing variables introduced. A test matrix was designed to progress in a series of steps; the first establishing a baseline, then introducing additional solvents or other variables. Variables included normal test plan delay times, pre-bond solvent hand-wipes and contaminants. Each condition tested utilized standard QLS hardware bonded with natural rubber, two separate technicians and three replicates. This paper will report the results and conclusions of this investigation.

Thornton, Tony N.↗

NASA NTRS2008

Effect of Pressure on Piloted Ignition Delay of PMMA

In order to reduce the risk of decompression sickness associated with spacewalks, NASA is considering designing the next generation of exploration vehicles and habitats with a different cabin environment than used previously. The proposed environment uses a total cabin pressure of 52.7 to 58.6 kPa with an oxygen concentration of 30 to 34% by volume and was chosen with material flammability in mind. Because materials may burn differently under these conditions and there is little information on how this new environment affects the flammability of the materials onboard, it is important to conduct material flammability experiments at the intended exploration atmosphere. One method to evaluate material flammability is by its ease of ignition. To this end, piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to this new environment. In these tests, polymethylmethacylate (PMMA) was exposed to a range of oxidizer flow velocities and externally applied heat fluxes. The ultimate goal is to determine the individual effect of pressure and the combined effect of pressure and oxygen concentration on the ignition delay. Tests were conducted for a baseline case of normal pressure and oxygen concentration, low pressure (58.6 kPa) with normal oxygen (21%). Future work will focus on low pressure with 32% oxygen concentration (space exploration atmosphere - SEA) conditions. It was found that reducing the pressure while keeping the oxygen concentration at 21% reduced the ignition time by 17% on average. It was also noted that the critical heat flux for ignition decreases in low-pressure conditions. Because tests conducted in standard atmospheric conditions will underpredict the flammability of materials intended for use on spacecraft, fire safety onboard at exploration atmospheres may be compromised.

McAllister, Sara↗

NASA NTRS2016

National Unmanned Aerial System Standardized Performance Testing and Rating (NUSTAR)

The overall objective of the NUSTAR Capability is to offer standardized tests and scenario conditions to assess performance of the UAS. The following are goals of the NU-STAR: 1. Create a prototype standardized tests and scenarios that vehicles can be tested against. 2. Identify key performance parameters of all UAS and their standardized measurement strategy. 3. Develop standardized performance reporting method (e.g., consumer report style) to assist prospective buyers. 4. Identify key performance metrics that could be used by judged towards overall safety of the UAS and operations. 5. If vehicle certification standard is made by a regulatory agency, the performance of individual UAS could be compared against the minimum requirement (e.g., sense and avoid detection time, stopping distance, kinetic energy, etc.).

Testing↗

DOE OSTI2025

Creation of a Weather Drivers Test Suite for Inclusion in ASHRAE Standard 140

Weather conditions are an important boundary condition for building performance simulation (BPS) calculations. For existing test cases in ASHRAE Standard 140 "Method of Test for Evaluating Building Performance Simulation Software" (ANSI/ASHRAE 2020), it was assumed that the software being tested could adequately read and interpret the weather data in the provided standard weather files. As differences between the programs have been reduced and as more programs have shifted to sub-hourly time steps this assumption has become more stretched. To address these concerns a new test suite testing a program's ability to read and interpret the data from a standard weather file was developed. The purpose of the test suite is to test the use of the typical data used from standard weather files.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRSDate not supplied

BEAST: Expanding Sustainable Data Infrastructure for High-Enthalpy Facilities

Reproducible, data-driven thermal protection system (TPS) research requires that experimental records from high-enthalpy testing be consistently structured, traceable, and accessible across campaigns and institutions. In practice, however, arcjet and plasma facilities data remain largely fragmented: raw diagnostics are stored in ad hoc formats, material sample histories are disconnected from test conditions, and metadata standards are absent, precluding systematic cross-campaign analysis and long-term reuse. BEAST (Backend for Experiment Analysis, Storage, and Traceability) is an open-source, web-based platform that addresses these limitations by providing a unified, queryable infrastructure for high-enthalpy ground-test data [1]. First presented at the 15th Ablation Workshop [2], BEAST has since undergone significant development. The platform ingests and structures multi-channel time-series diagnostics, facility configurations, and material property records within a common provenance model, ensuring end-to-end traceability from raw sensor acquisition to reduced experimental quantities. A versioned material library links specimen identity and processing history to the specific runs in which each sample was tested. An integrated modeling workbench enables training and evaluation of regression models directly on archived experimental data, supporting condition interpolation and the construction of empirical material response databases. Beyond its original deployment at NASA Ames Research Center, BEAST has been designed to be facility-agnostic, with ongoing efforts to extend its adoption to other facilities. Its modular architecture accommodates heterogeneous diagnostic setups and facility types, and its future open-source distribution allows institutions to build on a common data standard rather than maintaining isolated, bespoke solutions. BEAST is further integrated within a broader ecosystem of companion tools: arcjetCV [3] extracts recession rates and shock standoff distances from high-speed video using computer vision, and miniSTARscan [4] provides sub-minute, portable photogrammetric surface reconstruction of test articles before and after exposure. All tools share a common data schema, enabling seamless ingestion of surface geometry, imagery, and time-series data into a single, coherent experimental record.

Database↗

NASA NTRSDate not supplied

BEAST: Expanding Sustainable Data Infrastructure for High-Enthalpy Facilities

Database↗

NASA NTRS1982

Evaluation of fuel injection configurations to control carbon and soot formation in small GT combustors

An experimental program to investigate hardware configurations which attempt to minimize carbon formation and soot production without sacrificing performance in small gas turbine combustors has been conducted at the United Technologies Research Center. Four fuel injectors, embodying either airblast atomization, pressure atomization, or fuel vaporization techniques, were combined with nozzle air swirlers and injector sheaths, and evaluated at test conditions which included and extended beyond standard small gas turbine combustor operation. Extensive testing was accomplished with configurations embodying either a spill return or a T-vaporizer injector. Minimal carbon deposits were observed on the spill return nozzle for tests using either Jet A or ERBS test fuel. A more extensive film of soft carbon was observed on the vaporizer after operation at standard engine conditions, with large carbonaceous growths forming on the device during off-design operation at low combustor inlet temperature. Test results indicated that smoke emission levels depended on the combustor fluid mechanics (especially the mixing rates near the injector), the atomization quality of the injector and the fuel hydrogen content.

Rosfjord, T. J.↗

NASA NTRS2003

Evaluation of Charge Storage and Decay in Spacecraft Insulators

Two reports discuss methods for evaluating the magnitude of electrostatic charging that occurs in spacecraft dielectric materials (in particular, polyimides) during prolonged exposure to radiation in outer space. The reports describe experiments on the electrical resistivities and charge-storage properties of polyimide specimens in a dark, evacuated environment, both before and after 5-megarad exposures to rays from cobalt-60. The experiments were designed to measure these properties not under standard conditions prescribed for testing dielectrics in air but, rather, under conditions approximating those in the intended spacecraft applications. The results of the experiments showed that the electrical resistivities of the insulations as determined under these conditions are greater, by a factor of roughly a thousand, than those determined under the standard conditions and that the gamma irradiation reduced resistivities marginally.

Frederickson, Arthur↗

DOE OSTI2020

Graphite Licensing (ASME) and Testing (ASTM) Technical Assistance

DOE ART Graphite R&D program is currently involved in developing the structural code for licensing the new High Temperature Reactor (HTR) designs through the ASME Boiler Pressure Vessel Code (BPVC). The basic structural design code for graphite core components has been written, approved, and within the BPVC since 2012. However, several areas within the graphite code remain to be improved, specifically the addition of material property changes resulting from environmental degradation (neutron flux and oxidation). The incorporation of this data, which can significantly affect the graphite components and alter the structural integrity of the core during operation, is proving to be an important activity. How this data will be incorporated within the code and how it will be used for license applications will be critical to a number of HTR applicants in the future. These modifications to the code must take into account the unique irradiation and oxidation response of the wide spectrum of available nuclear graphite grades currently under consideration for HTR applications. Additionally, the ASME BPVC requires material property testing within the expected operational conditions of the HTR core including neutron radiation flux, elevated temperatures, and after chronic/acute oxidation of the graphite components. Currently, no standardized graphite testing methods are approved for these environmental conditions. New American Society for Testing and Materials (ASTM) standardized tests for elevated temperature testing, small sample testing, and testing after oxidation must be developed to support the requirements within the ASME code.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2024

Sulphate resistance of low‐clinker engineered cementitious composites examined by MicroXRF imaging

Abstract Engineered cementitious composites (ECC) are a class of high‐performing fibre‐reinforced cementitious materials recognised for their increased ductility and durability compared to conventional cement‐based materials, owing to their autogenously controlled tight crack widths, even when subjected to high strains. To reduce ECC's environmental impact, this research examines the use of a low‐clinker binder − limestone‐calcined clay cement (LC3) − as an alternative to portland cement (PC), along with fly ash to further reduce the clinker proportion and the embodied CO 2 of the formulations. In conventional concrete, LC3 hydrates to a denser microstructure resulting from the synergistic reaction between limestone and calcined clay. At the lower water contents typical of ECC and with the presence of fly ash, the influence of the binder composition on the microstructure is difficult to anticipate. To examine the influence of these compositional variables on microstructure, permeability and durability, the sulphate resistance of LC3‐based ECC is explored. Specifically, the ECC‐LC3 blends are designed with high clinker replacement rate of 75% by mass of binder and contain either conventional fly ash or reclaimed fly ash at 50% by mass of binder. Expansion of ECC‐LC3 samples subjected to standard sodium sulphate test conditions was measured up to 12 months and the depth of penetration of sulphates into the ECC‐LC3 of varying compositions was quantified using micro‐X‐Ray Fluorescence (microXRF) imaging and modelling. The expansion results show that the ECC‐LC3 formulations performed better than the PC samples and can provide adequate resistance to external sulphate attack, even when reclaimed fly ashes are used in place of the conventional ash. In addition, the shallow penetration of sulphate into these cementitious composites demonstrates the low diffusion coefficients values that were determined using the quantitative data from MicroXRF imaging.

Microscopy↗

NASA NTRS2004

High Reynolds Number Thermal Stability Experiments

This work represents preliminary thermal stability results for liquid hydrocarbon fuels. High Reynolds Number Thermal Stability experiments with Jet A and RP-1 resulted in a quantitative measurement of the thermal stability. Each fuel flowed through a heated capillary tube that held the outlet temperature at 290 C. An optical pyrometer measured the surface temperature of the tube at 12 locations as a function of time. The High Reynolds Number Thermal Stability number was then determined using standards published by the American Society for Testing and Materials. The results for Jet A showed lower thermal stability than similar tests conducted at another facility. The RP-1 results are the first reported using this technique. Because the temperature rise on the capillary tube during testing for the RP-1 fuels was not significant, a new standard for the testing conditions should be developed for these types of fuels.

Emens, Jessica M.↗

DOE OSTI2023

Generalizing mkFit and its Application to HL-LHC

mkFit is an implementation of the Kalman filter-based track reconstruction algorithm that exploits both thread- and data-level parallelism. In the past few years the project transitioned from the R&D phase to deployment in the Run-3 offline workflow of the CMS experiment. The CMS tracking performs a series of iterations, targeting reconstruction of tracks of increasing difficulty after removing hits associated to tracks found in previous iterations. mkFit has been adopted for several of the tracking iterations, which contribute to the majority of reconstructed tracks. When tested in the standard conditions for production jobs, speedups in track pattern recognition are on average of the order of 3.5x for the iterations where it is used (3-7x depending on the iteration). Multiple factors contribute to the observed speedups, including vectorization and a lightweight geometry description, as well as improved memory management and single precision. Efficient vectorization is achieved with both the icc and the gcc (default in CMSSW) compilers and relies on a dedicated library for small matrix operations, Matriplex, which has recently been released in a public repository. While the mkFit geometry description already featured levels of abstraction from the actual Phase-1 CMS tracker, several components of the implementations were still tied to that specific geometry. We have further generalized the geometry description and the configuration of the run-time parameters, in order to enable support for the Phase-2 upgraded tracker geometry for the HL-LHC and potentially other detector configurations. The implementation strategy and high-level code changes required for the HL-LHC geometry are presented. Speedups in track building from mkFit imply that track fitting becomes a comparably time consuming step of the tracking chain.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1993

Teaching high-performance skills using above-real-time training

The above real-time training (ARTT) concept is an approach to teaching high-performance skills. ARTT refers to a training paradigm that places the operator in a simulated environment that functions at faster than normal time. It represents a departure from the intuitive, but not often supported, feeling that the best practice is determined by the training environment with the highest fidelity. This approach is hypothesized to provide greater 'transfer value' per simulation trial, by incorporating training techniques and instructional features into the simulator. Two related experiments are discussed. In the first, 25 naive male subjects performed three tank gunnery tasks on a simulator under varying levels of time acceleration (i.e., 1.0x, 1.6x, 2.0x, sequential, and mixed). They were then transferred to a standard (1.0x) condition for testing. Every accelerated condition or combination of conditions produced better training and transfer than the standard condition. Most effective was the presentation of trials at 1.0x, 1.6x, and 2.0x in a random order during training. Overall, the best ARTT group scored about 50 percent higher and trained in 25 percent less time compared to the real-time control group. In the second experiment, 24 mission-capable F-16 pilots performed three tasks on a part-task F-16A flight simulator under varying levels of time compression (i.e., 1.0x, 1.5x, 2.0x, and random). All subjects were then tested in a real-time environment. The emergency procedure (EP) task results showed increased accuracy for the ARTT groups. In testing (transfer), the ARTT groups not only performed the EP more accurately, but dealt with a simultaneous enemy significantly better than a real-time control group. Although the findings on an air combat maneuvering task and stern conversion task were mixed, most measures indicated that the ARTT groups performed better and faster than a real-time control group. Other implications for ARTT are discussed along with future research directions.

Guckenberger, Dutch↗

DOE OSTI2023

In Vitro Thrombogenicity Testing of Biomaterials in a Dynamic Flow Loop: Effects of Length and Quantity of Test Samples

Abstract The results of in vitro dynamic thrombogenicity testing of biomaterials and medical devices can be significantly impacted by test conditions. To develop and standardize a robust dynamic in vitro thrombogenicity tool, the key test parameters need to be appropriately evaluated and optimized. We used a flow loop test system previously developed in our laboratory to investigate the effects of sample length and the number of samples per test loop on the thrombogenicity results. Porcine blood heparinized to a donor-specific target concentration was recirculated at room temperature through polyvinyl chloride (PVC) tubing loops containing test materials for 1 h at 200 mL/min. Four test materials (polytetrafluoroethylene (PTFE), latex, PVC, and silicone) with various thrombotic potentials in two sample lengths (12 and 18 cm) were examined. For the 12-cm long materials, two different test configurations (one and two samples per loop) were compared. Thrombogenicity was assessed through percent thrombus surface coverage, thrombus weight, and platelet count reduction in the blood. The test system was able to effectively differentiate the thrombogenicity profile of the materials (latex > silicone > PVC ≥ PTFE) at all test configurations. Increasing test sample length by 50% did not significantly impact the test results as both 12 and 18 cm sample lengths were shown to equally differentiate thrombotic potentials between the materials. The addition of a second test sample to each loop did not increase the test sensitivity and may produce confounding results, and thus a single test sample per loop is recommended.

Engineering↗