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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Foreword: Special Section on Multiphysics Aspects of Power Electronics Packaging—Power Die, Power Module, and Converter Level: Part 2

Power electronics are increasingly being used to condition electricity for a wide array of applications, such as transportation (on land, air, and water), data centers, radio frequency, directed energy, wind, solar, and grid-tied applications. Here, to increase power density, performance, efficiency, and reliability-as well as to reduce cost-innovations and developments are needed in the multiphysics packaging of power electronics at a die, module, and converter level. This includes fundamental R&D related to emerging high-voltage, high-temperature, and high-switching-frequency power electronics, packaging materials, thermal materials and interfaces, fluid-based thermal management technologies, reliability, condition monitoring, and prognostics. Latest developments in this area are published as a Special Section on Multiphysics Aspects of Power Electronics Packaging. The first part was published in the May 2024 issue of the IEEE Transactions on Components, Packaging and Manufacturing Technology (Volume 14, Issue 5). The second part of that Special Section is being published in this issue. A brief summary of the papers included in the second part are given below.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Low-temperature sprayed SnO x nanocomposite films with enhanced hole blocking for efficient large area perovskite solar cells

Scalable fabrication of charge transport layers with high uniformity and compactness is essential for the commercialization of perovskite solar cells (PSCs). Cost-effective deposition of high-quality electron transport layers (ETLs) is a particularly important step to achieve low-cost, efficient and large-area PSCs. Here, an open-air (relative humidity of 40–50%) and low-temperature (≤100 °C) ultrasonic spray coating of tin oxide (SnO 2 ) nanocomposite films incorporating nanocrystalline SnO 2 nanoparticles in an amorphous SnO x matrix is demonstrated to fabricate large-area ETLs for planar PSCs. The optimized SnO 2 /SnO x nanocomposite exhibits significantly enhanced hole-blocking and high-power conversion efficiencies of 18% and 16% for planar PSCs with an active area of 0.2 cm 2 and 1 cm 2 , respectively. More importantly, the devices show little current–voltage hysteresis as well as good shelf-life stability by maintaining ~90% of the initial performance without encapsulation after 2500 hours storage under inert conditions. Additionally, high voltages of >6.0 V have been obtained for solar modules of 2.1 cm 2 aperture area comprising six sub-cells in series, suggesting that the low-temperature, open-air and fast spray coating is suitable and transferable to deposit large-area charge transport layers for scalable PSCs or other optoelectronic devices.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2000

Development of a High Output Fluorescent Light Module for the Commercial Plant Biotechnology Facility

To maximize the use of available resources provided onboard the International Space Station, the development of an efficient lighting 1 system is critical to the overall performance of the CPBF. Not only is it important to efficiently generate photon energy, but thermal loads on the CPBF Temperature and Humidity Control System must be minimized. By utilizing optical coatings designed to produce highly diffuse reflectance in the visible wavelengths while minimizing reflectance in the infrared region, the design of the fluorescent light module for the CPBF is optimized for maximum photon flux, spatial uniformity and energy efficiency. Since the Fluorescent Light Module must be fully enclosed to meet (ISS) requirements for containment of particulates and toxic materials, heat removal from the lights presented some unique design challenges. By using the Express Rack moderate C, temperature-cooling loop, heat is rejected by means of a liquid/air coolant manifold. Heat transfer to the manifold is performed by conduction using copper fins, by forced air convection using miniature fans, and by radiation using optically selective coatings that absorb in the infrared wavelengths. Using this combination of heat transfer mechanisms builds in redundancy to prevent thermal build up and premature bulb failure.

Turner, Mark↗
NASA NTRSDate not supplied

Improved Peatland Hydrology and L-Band Microwave Radiative Transfer Modeling in Version 7 of the SMAP Level-4 Soil Moisture Data Assimilation Product

The NASA Soil Moisture Active Passive (SMAP) mission Level-4 Soil Moisture (L4_SM) product provides global, 9-km resolution, 3-hourly surface (0-5 cm) and root-zone (0-100 cm) soil moisture from April 2015 to present with a mean latency of 2.5 days from the time of observation. The L4_SM estimates are derived from the assimilation of SMAP L-band (1.4 GHz) brightness temperature (Tb) observations into the NASA Catchment land surface model. The recently released Version 7 of L4_SM comprises two key advances. First, the Catchment model now includes the recently developed PEATCLSM hydrology module for peatlands and uses an updated global map of peatlands. Second, revised parameters are used in the L-band radiative transfer model that converts the simulated soil moisture and temperature estimates into Tb predictions for use in the radiance-based L4_SM analysis. Specifically, the L-band scattering albedo, soil roughness, and vegetation opacity climatology are obtained from the SMAP Level-2 dual-channel soil moisture retrieval product. In this presentation, we examine the improvements gained with the model and parameter changes. In peatlands, the dynamics of water table depth, surface soil moisture and evapotranspiration are considerably improved in L4_SM Version 7 over Version 6 when evaluated against in situ measurements. These improvements are also manifested in smaller Tb observation-minus-forecast residuals.

SMAP↗
DOE OSTI2023

Functional variability in specific root respiration translates to autotrophic differences in soil respiration in a temperate deciduous forest

CO 2 release from forest soils (R s ) is a prominent flux in the global carbon cycle. Rs is derived from roots (autotrophic respiration, R a ) and microbial (heterotrophic) respiration and is highly dynamic, as it depends on edaphic and environmental conditions as well as root functional traits and microbial community composition. It is unclear how root functional traits affect root and microbial respiration rates; however, their consideration may help parse out the relative contributions of root and microbial respiration to R s . At a temperate forest site, root systems of 3–4 functional root orders and their surrounding surface soil were carefully excavated and placed into custom trays designed to repeatedly measure R s in situ on eight temperate tree species that varied in their root functional strategies and mycorrhizal affinity. R s was measured bi-weekly to monthly for nearly one year using a custom chamber attached to a gas exchange system. R s varied over time, ranging from 0.3 to 12 µmol m -2 s -1 . Comparable root systems of the same species were excised from the soil and specific root respiration rates (R r ) were measured. Rr ranged from 2.5 to 9.0 nmol g -1 s -1 and was negatively correlated with root tissue density and positively related to root tissue nitrogen concentration. Using R r to estimate R a , we estimate that R a accounts for <10%, on average 2–3%, of R s for individual root systems (averaging 1.2 g dry biomass) housed in surrounding soil (average 1.3 kg dry mass) in situ; thus, Ra was roughly 20 times greater than Rh per unit mass. The contribution of R a peaked in the fall and coincided with leaf senescence of the forest canopy. A soil-sterilizing experimental treatment designed to help isolate R a in situ reduced bacterial biomass and shifted fungal community composition, but there was no reduction in Rs of the in-situ root-soil tray systems. The relative R a to R s ratio increased with root functional strategies characterized by greater specific root length and tip abundance, but also to greater root tissue density. The ratio of R a to R s also increased with warmer soil temperatures and decreased slightly with increasing soil moisture. We discuss how incorporating root functional traits as modulators of the autotrophic contribution to R s could be considered when modeling total soil CO 2 efflux from forests.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Brittle-to-Ductile Transitions of Polyelectrolyte Complexes: Humidity, Temperature, and Salt

Polyelectrolyte complexation is an entropically driven, associative phase separation that results in a polymer-rich polyelectrolyte complex (PEC) and a polymer-poor supernatant. PECs show promise as a new class of sustainable materials since they can be processed using aqueous solutions rather than organic solvents. Previous reports have looked at the mechanical properties and glass transitions of PECs as a function of temperature, relative humidity (rH), and salt concentration (CS), but establishing a universal understanding of how these parameters affect PEC mechanics has yet to be achieved. We examined the effects of temperature, rH, and CS on the mechanical properties of PECs formed from poly(methacrylic acid) and poly(trimethyl aminoethyl methacrylate) with a goal of establishing design rules for their mechanical response. Relative humidity was shown to have the most dramatic effect on the mechanical properties, with temperature and salt concentration having far less of an impact. Furthermore, we observed that the glass transition of PECs is tied to both temperature and relative humidity, creating a glass transition rH g /T g line that can be modulated by added salt. Finally, we looked at the thermodynamics behind the glass transition of PECs, which yielded similar energies as the condensation of water. Here, we propose the use of water and/or salt as a low energy and efficient method of processing PECs for various applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Ultrafine Interwoven Dendritic Cu 2 Se/CuFeSe 2 Composites with Enhanced Thermoelectric Performance

As an effort to develop high-performance and stable copper chalcogenide thermoelectrics, several (1-x)Cu 2 Se/(x)CuFeSe 2 composites were successfully synthesized via a one-step solid-state transformation of CuSe 2 template. Uniform ultrafine dendritic structures consisting of interweaving Cu 2 Se and CuFeSe 2 nanofibers were observed in samples with low Fe content (0.05 ≤ x ≤ 0.1). Increasing the Fe content to x = 0.5 led to phase segregation into Cu 2 Se-rich region with embedded CuFeSe 2 fine structures interwoven with CuFeSe 2 -rich region containing Cu 2 Se nanofibers. The formation of such an entwined dendritic structure is believed to arise from the temperature-dependent solubility of CuFeSe 2 in the Cu 2 Se matrix. The dynamic dissolution of CuFeSe 2 into the Cu 2 Se at high temperatures leads to temperature-dependent doping of the Cu 2 Se matrix, enabling drastic enhancements of thermoelectric power factor at high temperatures. As a result, such a strategy is expected to be a powerful tool for properties modulation in thermoelectric materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Robust cycloid crossover driven by anisotropy in the skyrmion host GaV 4 S 8

We report on the anomalous magnetization dynamics of the cycloidally modulated spin textures under the influence of uniaxial anisotropy in multiferroic GaV 4 S 8 . The temperature and field dependence of the linear ac susceptibility [$χ'_{1ω}$ (T, H)], AC magnetic loss [$χ''_{1ω}$ (T, H)], and nonlinear AC magnetic response [$M_{3ω}$ (T, H)] are examined across the magnetic phase diagram in the frequency range f = 10 - 10 000 Hz. According to recent theory, skyrmion vortices under axial crystal symmetry are confined along specific orientations, resulting in enhanced robustness against oblique magnetic fields and altered spin dynamics. We characterize the magnetic response of each spin texture and find that the dynamic rigidity of the Néel skyrmion lattice appears enhanced compared to Bloch-type skyrmions in cubic systems, even in the multidomain state. Anomalous M 3 ω and strong dissipation emerge over the same phase regime where strong variations in the cycloid pitch were observed on lowering temperature in recent small-angle neutron-scattering experiments [White et al., Phys. Rev. B 97, 020401(R) (2018)]. Here, we show that strong anisotropy also drives an extended crossover of the zero-field cycloid texture in GaV 4 S 8 . The frequency dependence of these dynamic signatures is consistent with that of a robust anharmonic spin texture exhibiting a correlated domain arrangement. The results underpin the essential role of magnetic anisotropy in enhancing the rigidity of topological spin textures for diverse applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Total-Ionizing-Dose Effects on Long-term Data Retention Characteristics of Commercial 3-D NAND Memories

This article evaluates the data retention characteristics of irradiated multi-level cell (MLC) 3-D NAND flash memories. We irradiate the memory chips by a Co-60 gamma-ray source for up to 50 krad(Si) and then write a random data pattern on the irradiated chip to find its retention characteristics. The experimental results show that the data retention property of the irradiated chips is significantly degraded compared to the un-irradiated ones. We evaluate two independent strategies to improve the data retention characteristics of the irradiated chips. Furthermore, the first method involves high-temperature annealing of the irradiated chip while the second method suggests pre-programming the memory modules before deploying them in radiation-prone environments.

3-D NAND flash↗
DOE OSTI2023

Upscaling of asymmetric hollow fiber‐supported thin film membranes for oxygen separation from air: Proof of concept

Abstract Hollow fiber membranes demonstrate various advantages for high performance oxygen separation. However, the small diameters of hollow fibers and the brittleness of ceramics limit their mechanical strength, imposing great difficulties on stack and module development. Gas‐tight sealing is another challenge for upscaling of hollow fiber membrane technology. Low temperature sealant materials of epoxy resin or silicon are typically used for hollow fiber stacks, requiring that the sealing portions be located out of hot zone. Consequently, only partial length of hollow fibers participates in oxygen permeation. In this study, upscaling of our recently developed asymmetric hollow fiber‐supported thin film membranes is conducted, where individual hollow fibers are assembled in parallel to form a stack. A reliable gas‐tight sealing is obtained by combining ceramic paste with conductive adhesive ink cohesively. Comprehensive oxygen permeation test is conducted with the sealing portions being in hot zone and compared with a single hollow fiber membrane. Fundamental mechanism is discussed to understand the performances and their differences. An accelerated long‐term test (∼320 h, 16 thermal cycles) demonstrates excellent stability and robustness of the stack and sealing. The characterization of post‐test samples further confirms excellent stability and robustness of the phases and microstructures of the stack.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Cryogenic C-band wavelength division multiplexing system using an AIM Photonics Foundry process design kit

Cryogenic environments make superconducting computing possible by reducing thermal noise, electrical resistance and heat dissipation. Heat generated by the electronics and thermal conductivity of electrical transmission lines to the outside world constitute two main sources of thermal load in such systems. As a result, higher data rates require additional transmission lines which come at an increasingly higher cooling power cost. Hybrid or monolithic integration of silicon photonics with the electronics can be the key to higher data rates and lower power costs in these systems. We present a 4-channel wavelength division multiplexing photonic integrated circuit (PIC) built from modulators in the AIM Photonics process development kit (PDK) that operate at 25 Gbps at room temperature and 10 Gbps at 40 K. We further demonstrate 2-channel operation for 20 Gbps aggregate data rate at 40 K using two different modulators/wavelengths, with the potential for higher aggregate bit rates by utilizing additional channels.

42 ENGINEERING↗
DOE OSTI2021

Surface Sampling Techniques for the Canister Deposition Field Demonstration

This report describes plans for dust sampling and analysis for the multi-year Canister Deposition Field Demonstration. The demonstration will use three commercial 32PTH2 NUHOMS welded stainless steel storage canisters, which will be stored at an ISFSI site in Advanced Horizontal Storage Modules. One canister will be unheated; the other two will have heaters to achieve canister surface temperatures that match, to the degree possible, spent nuclear fuel (SNF) loaded canisters with heat loads of 10 kW and 40 kW. Surface sampling campaigns will take place on a yearly or bi-yearly basis. The goal of the planned dust sampling and analysis is to determine important environmental parameters that impact the potential occurrence of stress corrosion cracking on SNF dry storage canisters. Specifically, the size, morphology, and composition of the deposited dust and salt particles will be quantified, as well as the soluble salt load per unit area and the rate of deposition, as a function of canister surface temperature, location, time, and orientation. Sampling locations on the canister surface will nominally include 25 locations, corresponding to 5 circumferential locations at each of the 5 longitudinal locations. At each sampling location, a 2x2 sampling grid (containing 4 sample cells) will be painted onto the metal surface. During each sampling campaign, two samples at each sampling location will be collected, in a specific routine to measure both periodic (yearly or bi-yearly) and cumulative deposition rates. For each sample, a wet and a dry sample will be collected. Wet samples will be analyzed to determine the composition of the soluble salt fraction and to estimate salt loading per unit area. Dry samples will be analyzed to assess particle size, morphology, mineralogy, and identity (e.g. for floral/faunal fragments). The data generated by this proposed sampling plan will provide detailed information on dust and salt aerosol deposits on spent nuclear fuel canister surfaces. The anticipated results include information regarding particle compositions, size distributions, and morphologies, in addition to particle deposition rates as a function of canister surface location, orientation, time, and temperature. The information gathered during the Canister Deposition Field Demonstration is critical for ongoing efforts to develop a detailed understanding of the potential for stress corrosion cracking on SNF dry storage canisters

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1979

Test and evaluation of Fern Engineering Company, Incorporated, solar heating and hot water system

Tests, test results, examination and evaluation by Underwriters Laboratory, Inc., of a single family solar heating and hot water system consisting of collector, storage, control, transport, and data acquisition are presented. The structural characteristics of the solar flat plate collectors were evaluated according to snow and wind loads indicated in various building codes to determine their suitability for use both Michigan and Pennsylvania where prototype systems were installed. The flame spread classification of the thermal insulation is discussed and the fire tests conducted on components are described. The operation and dielectrics withstand tests of the energy transport module indicate the module is capable of rated air delivery. Tests of the control panel indicate the relay coil temperatures exceed the temperature limits allowed for the insulating materials involved.

Source record↗
NASA NTRS1984

Development of engineering prototype of Life Support Module (LSM)

The development of an engineering prototype of a life support system is discussed. The module consists of an electrocardiogram, a defibrillator, a resuscitator, and an aspirator, as well as body temperature and blood pressure measuring instruments. A drug kit is included.

Source record↗
NASA NTRS1988

Infrared Remote Sensing Of The Martian Atmosphere

Distributions of temperature dust, vapors, and condensates measured. Report describes design and intended uses of developmental pressure-modulator infrared readimeter, PMIRR, carried aboard Mars Observer spacecraft. Applies remote-sensing techniques used to study atmosphere of Earth. Takes similar measurements from polar orbit around Mars. Nine-channel atmospheric sounder that employs filter and pressure-modulation gas-correlation infrared radiometry.

Mccleese, D. J.↗
NASA NTRS1987

Space power demonstrator engine, phase 1

The design, analysis, and preliminary test results for a 25 kWe Free-Piston Stirling engine with integral linear alternators are described. The project is conducted by Mechanical Technology under the direction of LeRC as part of the SP-100 Nuclear Space Power Systems Program. The engine/alternator system is designed to demonstrate the following performance: (1) 25 kWe output at a specific weight less than 8 kg/kW; (2) 25 percent efficiency at a temperature ratio of 2.0; (3) low vibration (amplitude less than .003 in); (4) internal gas bearings (no wear, no external pump); and (5) heater temperature/cooler temperature from 630 to 315 K. The design approach to minimize vibration is a two-module engine (12.5 kWe per module) in a linearly-opposed configuration with a common expansion space. The low specific weight is obtained at high helium pressure (150 bar) and high frequency (105 Hz) and by using high magnetic strength (samarium cobalt) alternator magnets. Engine tests began in June 1985; 16 months following initiation of engine and test cell design. Hydrotest and consequent engine testing to date has been intentionally limited to half pressure, and electrical power output is within 15 to 20 percent of design predictions.

Source record↗
NASA NTRS1992

Passive microwave precipitation mapping and retrieval simulation

A numerical simulation of the satellite-based multispectral passive microwave mapping and precipitation retrieval process is described. The simulation contains three major components: (1) the forward radiative transfer calculation; (2) the sensor observation simulation; and (3) the precipitation retrieval algorithm. Secondary components include a Karhunen-Loeve transformation module and antenna pattern deconvolution module. The simulation facilitates the investigation of candidate precipitation retrieval algorithms using sub-Nyquist brightness temperature imagery, and the comparison of the relative merits of proposed radiometric systems such as the EOS multispectral imaging microwave radiometer (MIMR), the tropical rainfall measurement mission (TRMM) microwave imager (TRMM TMI), and the geosynchronous satellite sensors. A procedure for retrieving rain rates using a statistical iterative approach is outlined.

Skofronick, G. M.↗
NASA NTRS1995

Liquid crystal point diffraction interferometer

A new instrument, the liquid crystal point diffraction-interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. This dissertation describes the theory of both the PDI and liquid crystal phase control. The design considerations for the LCPDI are presented, including manufacturing considerations. The operation and performance of the LCPDI are discussed, including sections regarding alignment, calibration, and amplitude modulation effects. The LCPDI is then demonstrated using two phase objects: defocus difference wavefront, and a temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to theoretical or independently measured results and show excellent agreement. A computer simulation of the LCPDI was performed to verify the source of observed periodic phase measurement error. The error stems from intensity variations caused by dye molecules rotating within the liquid crystal layer. Methods are discussed for reducing this error. Algorithms are presented which reduce this error; they are also useful for any phase-stepping interferometer that has unwanted intensity fluctuations, such as those caused by unregulated lasers.

Mercer, Carolyn R.↗