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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

A Modular and Flexible High-Frequency-Link Transformer with a Reduced Device Count and Zero High-Side Devices

In general, large power transformers (LPTs) are not interchangeable with each other and their high costs prohibit extensive spare inventories more so considering that on an average only 1.3 LPTs are manufactured for individual design. The latter pose a further challenge since given that the several existing LPTs are reaching their end of service lives, loss of plurality of such LPTs, that form the backbone of U.S. power grid, will clearly run into the problem of energy security related to the non-availability of sufficient spares (and extended lead time) exacerbated further by the fact that these spares are not interchangeable for installations at different locations. Conventional LPT cost millions of dollars and weighs significantly between approximately 100 and 400 tons. Two raw materials—copper and electrical steel—account for over 50 percent of the total cost of an LPT. In recent years, the price volatility of these two commodities in the global market has affected the manufacturing conditions and procurement strategy for LPTs. Transportation is also an important element of the total LPT cost, because an LPT can weigh significantly and often requires long-distance transport. Transporting an LPT is challenging—its large dimensions and heavy weight pose unique requirements to ensure safe and efficient transportation. Current road, rail, and port conditions are such that transportation is taking more time and becoming more expensive. Conventional low-frequency LPTs typically follow a monolithic approach to design due to historical reasons that need to transition to more modular and flexible (e.g., in voltage, impedance, and power flow) designs with ability to seamlessly/near-seamlessly scale. They should also have the ability to incorporate new technologies without in all cases redoing a LPT design from scratch. Given that the cost of raw materials has continued to increase, next-generation LPTs need to pursue avenues for reducing these costs. An added necessity is to reduce the transportability cost, which is significant in conventional LPTs. Further, given that LPTs are for the long term, they need to be durable, efficient, and fault tolerant with overloading capability. Given this backdrop, the objective and accomplishment of this one-year DOE (SPONSOR) R&D project, led by small business NextWatt LLC (PRIME, Lead PI: Dr. Sudip K. Mazumder) and University of Arkansas at Fayetteville (SUBAWARDEE, PI: Dr. Juan Balda) were to explore the design of a (8 – 20 kHz) high-frequency-link (HFL) based 100-MVA LPT with nominal voltage of 115/69 kV, with $15 - $22 dollars US per kVA when manufactured in “moderate” volume, with 99% energy-conversion efficiency, with 300% reduction in both volume and weight compared to a conventional LPT with the same electrical ratings, with impedance variation greater than 5%, with direct AC/AC power conversion capability, with very-high energy-conversion efficiency (using wide-bandgap SiC based field effect MOSFET devices) over a wide operating temperature, with reduction in both volume and weight with regard to conventional low frequency LPT, and with significant reduction in number of devices compared to state of the art solid state transformer topology.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1933

Wind tunnel research comparing lateral control devices, particularly at high angles of attack X : various control devices on a wing with a fixed auxiliary airfoil

Results are given of a series of systemic tests comparing lateral control devices with particular reference to their effectiveness at high angles of attack. These tests were made with two sizes of ordinary ailerons and different sizes of spoilers on a Clark Y wing model having a narrow auxiliary airfoil fixed ahead and above the leading edge, the chords of the main and auxiliary airfoils being parallel. In addition, the auxiliary airfoil itself was given angular deflection. The purpose was to provide rolling moments for lateral control. The tests were made in a 7 by 10 foot wind tunnel. They included both force and rotation tests to show the effect of the devices on the lift and drag characteristics of the wing and on the lateral stability characteristics, as well as lateral control. They showed that none of the aileron arrangements tried would give rolling control of an assumed satisfactory value at all angles of attack up to the stall. However, they would give satisfactory values, but at the expense of abnormally high deflections and very heavy hinge moments. The most effective combination of ailerons and spoilers gave satisfactory values of rolling moment at angles of attack below the stall, and the values did not fall off as rapidly above the stall as with ailerons alone. With an arrangement of this type having the proper relative proportions and linkage, it should be possible to obtain reasonably satisfactory yawing moments and control forces. Deflecting one-half of the auxiliary airfoil downward for the purpose of control gave strong favorable yawing moments at all angles of attack, but gave very small rolling moments at the low angles of attack.

Weick, Fred E↗
NASA NTRS2004

Measurement of Device Parameters Using Image Recovery Techniques in Large-Scale IC Devices

Devices that respond to radiation on a cell level will produce histograms showing the relative frequency of cell damage as a function of damage. The measured distribution is the convolution of distributions from radiation responses, measurement noise, and manufacturing parameters. A method of extracting device characteristics and parameters from measured distributions via mathematical and image subtraction techniques is described.

radiation↗
NASA NTRS2012

Verilog-A Device Models for Cryogenic Temperature Operation of Bulk Silicon CMOS Devices

Verilog-A based cryogenic bulk CMOS (complementary metal oxide semiconductor) compact models are built for state-of-the-art silicon CMOS processes. These models accurately predict device operation at cryogenic temperatures down to 4 K. The models are compatible with commercial circuit simulators. The models extend the standard BSIM4 [Berkeley Short-channel IGFET (insulated-gate field-effect transistor ) Model] type compact models by re-parameterizing existing equations, as well as adding new equations that capture the physics of device operation at cryogenic temperatures. These models will allow circuit designers to create optimized, reliable, and robust circuits operating at cryogenic temperatures.

Akturk, Akin↗
DOE OSTI2012

Devices, systems, and methods for harvesting energy and methods for forming such devices

Energy harvesting devices include a substrate coupled with a photovoltaic material and a plurality of resonance elements associated with the substrate. The resonance elements are configured to collect energy in at least visible and infrared light spectra. Each resonance element is capacitively coupled with the photovoltaic material, and may be configured to resonate at a bandgap energy of the photovoltaic material. Systems include a photovoltaic material coupled with a feedpoint of a resonance element. Methods for harvesting energy include exposing a resonance element having a resonant electromagnetic radiation having a frequency between approximately 20 THz and approximately 1,000 THz, absorbing at least a portion of the electromagnetic radiation with the resonance element, and resonating the resonance element at a bandgap energy of an underlying photovoltaic material. Methods for forming an energy harvesting device include forming resonance elements on a substrate and capacitively coupling the resonance elements with a photovoltaic material.

14 SOLAR ENERGY↗
DOE OSTI2014

Hetero-junction photovoltaic device and method of fabricating the device

A hetero-junction device and fabrication method in which phase-separated n-type and p-type semiconductor pillars define vertically-oriented p-n junctions extending above a substrate. Semiconductor materials are selected for the p-type and n-type pillars that are thermodynamically stable and substantially insoluble in one another. An epitaxial deposition process is employed to form the pillars on a nucleation layer and the mutual insolubility drives phase separation of the materials. During the epitaxial deposition process, the orientation is such that the nucleation layer initiates propagation of vertical columns resulting in a substantially ordered, three-dimensional structure throughout the deposited material. An oxidation state of at least a portion of one of the p-type or the n-type semiconductor materials is altered relative to the other, such that the band-gap energy of the semiconductor materials differ with respect to stoichiometric compositions and the device preferentially absorbs particular selected bands of radiation.

42 ENGINEERING↗
DOE OSTI2016

Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device and flow a heat transfer medium in a substantially axial direction through the heat transfer structure. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

42 ENGINEERING↗
DOE OSTI2017

Efficacy of an acoustic hailing device as an avian dispersal tool

Bird strikes are a major safety and financial concern for modern aviation. Audible stimuli are common bird dispersal techniques, but their effectiveness is limited by the saliency and relevance of the stimulus. Furthermore, high ambient sound levels present at airfields might require that effective audible stimuli rely more on total volume (i.e., exceeding physiological tolerances) than ecological relevance. Acoustic hailing devices (AHD) are capable of sound output with a narrow beam width and at volumes high enough to cause physical discomfort at long distances. We tested the effectiveness of an AHD as a dispersal tool on free-ranging birds recognized as hazardous to aviation safety at the Savannah River Site and Phinizy Swamp Nature Park in South Carolina and Georgia, respectively. Our study design included experimental trials with timed-interval counts of birds directly before and after AHD treatment. For most species, counts of birds associated with treatment periods (use of AHD) and control periods (no use of AHD) occurred on different days. Sound treatments yielded variable success at dispersing birds. Specifically, AHD treatment was effective for dispersing vultures (Coragyps atratus and Cathartes aura) and gulls (Laridae), and ineffective for dispersing blackbirds (Icteridae), diving ducks (Aythya, Bucephala, Oxyura), and coots (Fulica americana). These trials were conducted in a relatively quiet environment with birds that were unhabituated to excessive noise, and thus we cannot unequivocally recommend an AHD as a universally effective avian dispersing tool. Furthermore, future research should consider AHD testing integrated with other methods, as well as investigation of treatments that might be salient to specific target species.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Chaotic coordinates for the Large Helical Device

The theory of quadratic-flux-minimizing (QFM) surfaces is reviewed, and numerical techniques that allow high-order QFM surfaces to be efficiently constructed for experimentally relevant, non-integrable magnetic fields are described. As a practical example, the chaotic edge of the magnetic field in the Large Helical Device (LHD) is examined. A precise technique for finding the boundary surface is implemented, the hierarchy of partial barriers associated with the near-critical cantori is constructed, and a coordinate system, which we call chaotic coordinates, that is based on a selection of QFM surfaces is constructed that simplifies the description of the magnetic field, so that flux surfaces become “straight” and islands become “square.”.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Functional materials and devices by self-assembly

The field of self-assembly has moved far beyond early work, where the focus was primarily the resultant beautiful two- and three-dimensional structures, to a focus on forming materials and devices with important properties either otherwise not available, or only available at great cost. Over the last few years, materials with unprecedented electronic, photonic, energy-storage, and chemical separation functionalities were created with self-assembly, while at the same time, the ability to form even more complex structures in two and three dimensions has only continued to advance. Self-assembly crosscuts all areas of materials. Functional structures have now been realized in polymer, ceramic, metallic, and semiconducting systems, as well as composites containing multiple classes of materials. Finally, as the field of self-assembly continues to advance, the number of highly functional systems will only continue to grow and make increasingly greater impacts in both the consumer and industrial space.

Materials for Devices↗
DOE OSTI2019

Photo‐/Thermal‐Responsive Field‐Effect Transistor upon Blending Polymeric Semiconductor with Hexaarylbiimidazole toward Photonically Programmable and Thermally Erasable Memory Device

Abstract It is shown that the semiconducting performance of field‐effect transistors (FETs) with PDPP4T (poly(diketopyrrolopyrrole‐quaterthiophene)) can be reversibly tuned by UV light irradiation and thermal heating after blending with the photochromic hexaarylbiimidazole compound ( p ‐NO 2 ‐HABI). A photo‐/thermal‐responsive FET with a blend thin film of PDPP4T and p ‐NO 2 ‐HABI is successfully fabricated. The transfer characteristics are altered significantly with current enhanced up to 10 6 ‐fold at V G = 0 V after UV light irradiation. However, further heating results in the recovery of the transfer curve. This approach can be extended to other semiconducting polymers such as P3HT (poly(3‐hexyl thiophene)), PBTTT (poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b] thiophene)) and PDPPDTT (poly(diketopyrrolopyrrole‐dithienothiophene)). It is hypothesized that TPIRs (2,4,5‐triphenylimidazolyl radicals) formed from p ‐NO 2 ‐HABI after UV light irradiation can interact with charge defects at the gate dielectric–semiconductor interface and those in the semiconducting layer to induce more hole carriers in the semiconducting channel. The application of the blend thin film of PDPP4T and p ‐NO 2 ‐HABI is further demonstrated to fabricate the photonically programmable and thermally erasable FET‐based nonvolatile memory devices that are advantageous in terms of i) high ON/OFF current ratio, ii) nondestructive reading at low electrical bias, and iii) reasonably highly stable ON‐state and OFF‐state.

Liu, Yidong↗