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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Standard Analysis Report INV-SAR-81, Revision 0 Chemical and Cement Components 2023 Inventory Estimates for the Interim State Performance Assessment of the Waste Isolation Pilot Plant

This standard analysis report provides the estimates for the chemical (oxyanions and complexing agents) and cement components with a data collection cut-off date of December 31, 2023. These estimates will be included in a Performance Assessment Inventory Report developed for the U.S. Department of Energy (DOE) interim state repository configuration performance assessment (PA) for the 2026 Compliance Recertification Application (CRA).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1984

Electric utility acid fuel cell stack technology advancement

The principal effort under this program was directed at the fuel cell stack technology required to accomplish the initial feasibility demonstrations of increased cell stack operating pressures and temperatures, increased cell active area, incorporation of the ribbed substrate cell configuration at the bove conditions, and the introduction of higher performance electrocatalysts. The program results were successful with the primary accomplishments being: (1) fabrication of 10 sq ft ribbed substrate, cell components including higher performing electrocatalysts; (2) assembly of a 10 sq ft, 30-cell short stack; and (3) initial test of this stack at 120 psia and 405 F. These accomplishments demonstrate the feasibility of fabricating and handling large area cells using materials and processes that are oriented to low cost manufacture. An additional accomplishment under the program was the testing of two 3.7 sq ft short stacks at 12 psia/405 F to 5400 and 4500 hours respectively. These tests demonstrate the durability of the components and the cell stack configuration to a nominal 5000 hours at the higher pressure and temperature condition planned for the next electric utility power plant.

Congdon, J. V.↗
NASA NTRS1982

Cell module and fuel conditioner development

The phosphoric acid fuel cell module (stack) development which culminated in an 80 cell air-cooled stack with separated gas cooling and treed cooling plates is described. The performance of the 80 cell stack was approx. 100 mV per cell higher than that attained during phase 1. The components and materials performed stably for over 8000 hours in a 5 cell stack. The conceptual design of a fuel conditioning system is described.

Hoover, D. Q., Jr.↗
NASA NTRS2011

Advanced Spacesuit Portable Life Support System Oxygen Regulator Development and Testing

The advanced spacesuit portable life support system (PLSS) oxygen regulators represent an evolutionary approach to regulator development. Several technology development prototypes have been produced that borrow much of the mechanical regulator design from the well proven Shuttle/ISS Extravehicular Mobility Unit (EMU) Secondary Oxygen Regulator, but incorporate a motor-settable pressure set-point feature that facilitates significantly greater operational flexibility. For example, this technology would enable EVA to begin at a higher suit pressure, which would reduce pre-breathe time, and then slowly step down to a lower pressure to increase suit mobility for the duration of the EVA. Comprehensive testing of the prototypes was performed on the component level as well as part of the PLSS 1.0 system level testing. Results from these tests characterize individual prototype performance and demonstrate successful operation during multiple nominal and contingency EVA modes

Campbell, Colin↗
DOE OSTI2015

Comparison of algorithms for determination of rotation measure and Faraday structure. I. 1100–1400 MHz

Faraday rotation measures (RMs) and more general Faraday structures are key parameters for studying cosmic magnetism and are also sensitive probes of faint ionized thermal gas. A definition of which derived quantities are required for various scientific studies is needed, as well as addressing the challenges in determining Faraday structures. A wide variety of algorithms has been proposed to reconstruct these structures. In preparation for the Polarization Sky Survey of the Universe's Magnetism (POSSUM) to be conducted with the Australian Square Kilometre Array Pathfinder and the ongoing Galactic Arecibo L-band Feeds Array Continuum Transit Survey (GALFACTS), we run a Faraday structure determination data challenge to benchmark the currently available algorithms, including Faraday synthesis (previously called RM synthesis in the literature), wavelet, compressive sampling, and QU-fitting. The input models include sources with one Faraday thin component, two Faraday thin components, and one Faraday thick component. The frequency set is similar to POSSUM/GALFACTS with a 300 MHz bandwidth from 1.1 to 1.4 GHz. We define three figures of merit motivated by the underlying science: (1) an average RM weighted by polarized intensity, RM{sub wtd}, (2) the separation Δϕ of two Faraday components, and (3) the reduced chi-squared χ{sub r}{sup 2}. Based on the current test data with a signal-to-noise ratio of about 32, we find the following. (1) When only one Faraday thin component is present, most methods perform as expected, with occasional failures where two components are incorrectly found. (2) For two Faraday thin components, QU-fitting routines perform the best, with errors close to the theoretical ones for RM{sub wtd} but with significantly higher errors for Δϕ. All other methods, including standard Faraday synthesis, frequently identify only one component when Δϕ is below or near the width of the Faraday point-spread function. (3) No methods as currently implemented work well for Faraday thick components due to the narrow bandwidth. (4) There exist combinations of two Faraday components that produce a large range of acceptable fits and hence large uncertainties in the derived single RMs; in these cases, different RMs lead to the same Q, U behavior, so no method can recover a unique input model. Further exploration of all these issues is required before upcoming surveys will be able to provide reliable results on Faraday structures.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1992

Performance Evaluation and Modeling Techniques for Parallel Processors

In practice, the performance evaluation of supercomputers is still substantially driven by singlepoint estimates of metrics (e.g., MFLOPS) obtained by running characteristic benchmarks or workloads. With the rapid increase in the use of time-shared multiprogramming in these systems, such measurements are clearly inadequate. This is because multiprogramming and system overhead, as well as other degradations in performance due to time varying characteristics of workloads, are not taken into account. In multiprogrammed environments, multiple jobs and users can dramatically increase the amount of system overhead and degrade the performance of the machine. Performance techniques, such as benchmarking, which characterize performance on a dedicated machine ignore this major component of true computer performance. Due to the complexity of analysis, there has been little work done in analyzing, modeling, and predicting the performance of applications in multiprogrammed environments. This is especially true for parallel processors, where the costs and benefits of multi-user workloads are exacerbated. While some may claim that the issue of multiprogramming is not a viable one in the supercomputer market, experience shows otherwise. Even in recent massively parallel machines, multiprogramming is a key component. It has even been claimed that a partial cause of the demise of the CM2 was the fact that it did not efficiently support time-sharing. In the same paper, Gordon Bell postulates that, multicomputers will evolve to multiprocessors in order to support efficient multiprogramming. Therefore, it is clear that parallel processors of the future will be required to offer the user a time-shared environment with reasonable response times for the applications. In this type of environment, the most important performance metric is the completion of response time of a given application. However, there are a few evaluation efforts addressing this issue.

Dimpsey, Robert Tod↗
DOE OSTI2018

Effect of packaging and cooling plates on mechanical response and failure characteristics of automotive Li-ion battery modules

When a battery pack is subjected to external mechanical load, i.e. as in the case of crash, the individual cells experience significant deformations leading to the internal short circuit and possibly fire. The current investigation looks into effects of the inactive components (i.e. cooling plates and module protective enclosure) on deformation and failure of individual pouch cells. Experiments on large spherical indentation of electric vehicle battery module with and without such components have been performed. The results show that the presence of cooling plates overall reduces the force under out-of-plane indentation by approximately a factor of 1.5. It was established however that the failure in cells occurs at the same displacement of the indenter, regardless of the presence of the inactive elements in battery module structure. This underlines the necessity for formulation of the failure criterion based on critical strain, rather than critical stress measure. The findings suggest possibility of utilizing such battery modules in impact energy absorption scenarios, due to reduction in force by the cooling components. X-Ray computed tomography (XCT) has been performed on the cells as a non-destructive analysis of internal failure and the differences of failure mode induced by introduction of structural components are discussed.

25 ENERGY STORAGE↗
NASA NTRSDate not supplied

Fault Detection and Performance Monitoring of Propellers in Electric UAV

Unmanned aerial vehicles (UAVs) are used in various industries such as agriculture and logistics, to name but a few, where their applications are beyond basic mapping, surveillance, and photography. In near future, UAVs are expected to be used in package delivery service and larger electric vertical takeoff and landing vehicles will be employed for urban air mobility applications (air taxi). Thus, several electric propulsion systems will enter the low-altitude airspace with frequent take offs and landings. To achieve state-of-the-art safety standards under such high traffic density, UAVs will require in-time fault detection and performance monitoring of critical powertrain components. This work focuses on propeller blade performance and damage detection in electric UAVs. Propellers are the fastest moving component in an UAV; even a minor defect in the propeller blades could cause performance deterioration, with consequent challenges in flying through the planned trajectory or adhere to the safety requirements of the operation. Monitoring and updating aerodynamic efficiency of each rotor would therefore enable the detection of off-nominal propeller conditions thus magnifying the state-awareness of powertrain monitoring systems based on the acquired electrical signals. We use an extended Kalman filter-based parameter estimation algorithm that incorporates time history responses from UAV powertrain in conjunction with a full powertrain system model. Propeller fault detection is achieved by incorporating the aerodynamic parameters of propeller into the powertrain model. The proposed technique is successfully validated with numerical simulations.

Unmanned aerial vehicles↗
DOE OSTI2019

A Comparison of the Fatigue Life of Shot-Peened 4340M Steel with 100, 200, and 300% Coverage

Shot peening has been widely used for improving the fatigue performance of structural components. The objectives of this study are to increase the fatigue life of 4340M steel by shot peening and to compare performance at three different shot-peening coverages (100, 200, and 300%). The results show that the optimum coverage for 4340M steel is 200% in this experiment. Scanning electron microscopy (SEM) was used to evaluate the microstructural properties and estimate the depth and length of the resulting cracks. A proposed innovative technique, which still needs further verification, was applied to enable SEM to differentiate between the appearances of the three coverages. Residual stresses measured using x-ray diffraction showed that 200% coverage had comparatively the highest residual compressive stresses.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Analysis of the Tank 6F Final Characterization Samples-2012

The Savannah River National Laboratory (SRNL) was requested by Savannah River Remediation (SRR) to provide sample preparation and analysis of the Tank 6F final characterization samples to determine the residual tank inventory prior to grouting. Fourteen residual Tank 6F solid samples from three areas on the floor of the tank were collected and delivered to SRNL between May and August 2011. These Tank 6F samples were homogenized and combined into three composite samples based on a proportion compositing scheme and the resulting composite samples were analyzed for radiological, chemical and elemental components. Additional measurements performed on the Tank 6F composite samples include bulk density and water leaching of the solids to account for water soluble components. The composite Tank 6F samples were analyzed and the data reported in triplicate. Sufficient quality assurance standards and blanks were utilized to demonstrate adequate characterization of the Tank 6F samples. The main evaluation criteria were target detection limits specified in the technical task request document. While many of the target detection limits were met for the species characterized for Tank 6F some were not met. In a few cases, the relatively high levels of radioactive species of the same element or a chemically similar element precluded the ability to measure some isotopes to low levels. The isotopes whose detection limits were not met in all cases included Sn-126, Sb-126, Sb-126m, Eu-152, Cm- 243 and Cf-249. SRNL, in conjunction with the customer, reviewed all of these cases and determined that the impacts of not meeting the target detection limits were acceptable. Based on the analyses of variance (ANOVA) for the inorganic constituents of Tank 6F, all the inorganic constituents displayed heterogeneity. The inorganic results demonstrated consistent differences across the composite samples: lowest concentrations for Composite Sample 1, intermediate-valued concentrations for Composite Sample 2, and highest concentrations for Composite Sample 3. The Hg and Mo results suggest possible measurement outliers. However, the magnitudes of the differences between the Hg 95% upper confidence limit (UCL95) results with and without the outlier and the magnitudes of the differences between the Mo UCL95 results with and without the outlier do not appear to have practical significance. It is recommended to remove the potential measurement outliers. Doing so is conservative in the sense of producing a higher UCL95 for Hg and Mo than if the potential outliers were included in the calculations. In contrast to the inorganic results, most of the radionuclides did not demonstrate heterogeneity among the three Tank 6F composite sample characterization results.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1984

Reliability considerations for the total strain range version of strainrange partitioning

A proposed total strainrange version of strainrange partitioning (SRP) to enhance the manner in which SRP is applied to life prediction is considered with emphasis on how advanced reliability technology can be applied to perform risk analysis and to derive safety check expressions. Uncertainties existing in the design factors associated with life prediction of a component which experiences the combined effects of creep and fatigue can be identified. Examples illustrate how reliability analyses of such a component can be performed when all design factors in the SRP model are random variables reflecting these uncertainties. The Rackwitz-Fiessler and Wu algorithms are used and estimates of the safety index and the probablity of failure are demonstrated for a SRP problem. Methods of analysis of creep-fatigue data with emphasis on procedures for producing synoptic statistics are presented. An attempt to demonstrate the importance of the contribution of the uncertainties associated with small sample sizes (fatique data) to risk estimates is discussed. The procedure for deriving a safety check expression for possible use in a design criteria document is presented.

Wirsching, P. H.↗
NASA NTRS2009

Advanced Materials and Cell Components for NASA's Exploration Missions

This is an introductory paper for the focused session "Advanced Materials and Cell Components for NASA's Exploration Missions". This session will concentrate on electrochemical advances in materials and components that have been achieved through efforts sponsored under NASA's Exploration Systems Mission Directorate (ESMD). This paper will discuss the performance goals for components and for High Energy and Ultra High Energy cells, advanced lithium-ion cells that will offer a combination of higher specific energy and improved safety over state-of-the-art. Papers in this session will span a broad range of materials and components that are under development to enable these cell development efforts.

Reid, Concha M.↗
NASA NTRS2014

Additive Manufacturing Thermal Performance Testing of Single Channel GRCop-84 SLM Components

The surface finish found on components manufactured by sinter laser manufacturing (SLM) is rougher (0.013 - 0.0006 inches) than parts made using traditional fabrication methods. Internal features and passages built into SLM components do not readily allow for roughness reduction processes. Alternatively, engineering literature suggests that the roughness of a surface can enhance thermal performance within a pressure drop regime. To further investigate the thermal performance of SLM fabricated pieces, several GRCop-84 SLM single channel components were tested using a thermal conduction rig at MSFC. A 20 kW power source running at 25% duty cycle and 25% power level applied heat to each component while varying water flow rates between 2.1 - 6.2 gallons/min (GPM) at a supply pressure of 550 to 700 psi. Each test was allowed to reach quasi-steady state conditions where pressure, temperature, and thermal imaging data were recorded. Presented in this work are the heat transfer responses compared to a traditional machined OHFC Copper test section. An analytical thermal model was constructed to anchor theoretical models with the empirical data.

Garcia, Chance P.↗
NASA NTRS2015

Thermal Performance Testing of Single Channel GRCop-84 SLM Components

The surface finish found on components manufactured by sinter laser manufacturing (SLM) is rougher (0.013 - 0.0006 inches) than parts made using traditional fabrication methods. Internal features and passages built into SLM components do not readily allow for roughness reduction processes. Alternatively, engineering literature suggests that the roughness of a surface can enhance thermal performance within a pressure drop regime. To further investigate the thermal performance of SLM fabricated pieces, several GRCop‐84 SLM single channel components were tested using a thermal conduction rig at MSFC. A 20 kW power source running at 25% duty cycle and 25% power level applied heat to each component while varying water flow rates between 2.1 - 6.2 gallons/min (GPM) at a supply pressure of 500 to 750 psi. Each test was allowed to reach quasi‐steady state conditions where pressure, temperature, and thermal imaging data were recorded. Presented in this work are the heat transfer responses compared to a traditional machined OHFC Copper test section. An analytical thermal model was constructed to anchor theoretical models with the empirical data.

Garcia, Chance P.↗
NASA NTRS2006

Effect of Bending Stiffness of the Electroactive Polymer Element on the Performance of a Hybrid Actuator System (HYBAS)

An electroactive polymer (EAP)-ceramic hybrid actuation system (HYBAS) was developed recently at NASA Langley Research Center. This paper focuses on the effect of the bending stiffness of the EAP component on the performance of a HYBAS, in which the actuation of the EAP element can match the theoretical prediction at various length/thickness ratios for a constant elastic modulus of the EAP component. The effects on the bending stiffness of the elastic modulus and length/thickness ratio of the EAP component were studied. A critical bending stiffness to keep the actuation of the EAP element suitable for a rigid beam theory-based modeling was found for electron irradiated P(VDF-TrFE) copolymer. For example, the agreement of experimental data and theoretical modeling for a HYBAS with the length/thickness ratio of EAP element at 375 times is demonstrated. However, the beam based theoretical modeling becomes invalid (i.e., the profile of the HYBAS movement does not follow the prediction of theoretical modeling) when the bending stiffness is lower than a critical value.

Xu, Tian-Bing↗
DOE OSTI2017

Method for controlling start-up and steady state performance of a closed split flow recompression brayton cycle

A method of resolving a balanced condition that generates control parameters for start-up and steady state operating points and various component and cycle performances for a closed split flow recompression cycle system. The method provides for improved control of a Brayton cycle thermal to electrical power conversion system. The method may also be used for system design, operational simulation and/or parameter prediction.

42 ENGINEERING↗
DOE OSTI2015

Analytical optimal pulse shapes obtained with the aid of genetic algorithms

We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗