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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 OSTI2016

Automation and Database Collection and Extrapolation

This report highlights overall design consideration regarding automation and database collection and extrapolation prototype for Farmpod, LLC. There are potentially many combinations of software, hardware, and networking which suffices for the requirements. For this report, we suggest a Raspberry Pi 2 Model B for the hardware. We suggest the Mako application server for the user interface and RPIO python modules for automated software processes. At the present moment, security is not a major concern, but should be addressed during the initial design phase. The software stack consists of two primary components: the automated processes and application server to implement a user interface.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1998

The Role of the Strutjet Engine in New Global and Space Markets

The Strutjet, discussed in previous IAF papers, was originally introduced as an enabling propulsion concept for single stage to orbit applications. Recent design considerations indicate that this systems also provides benefits supportive of other commercial non-space applications. This paper describes the technical progress of the Strutjet since 1997 together with a rationale why Rocket Based Combined Cycle Engines in general, and the Strutjet in particular, lend themselves uniquely to systems having the ability to expand current space and open new global 'rapid delivery' markets. During this decade, Strutjet technology has been evaluated in over 1000 tests. Its design maturity has been continuously improved and desired features, like simple variable geometry and low drag flowpath resulting in high performance, have been verified. In addition, data is now available which allows the designer, who is challenged to maximize system operability and economic feasibility, to choose between hydrogen or hydrocarbon fuels for a variety of application. The ability exists now to apply this propulsion system to various vehicles with a multitude of missions. In this paper, storable hydrocarbon and gaseous hydrogen Strutjet RBCC test data as accomplished to date and as planned for the future is presented, and the degree of required technology maturity achieved so far is assessed. Two vehicles, using cryogenic propane fuel Strutjet engines, and specifically designed for rapid point-to-point cargo delivery between Pacific rim locations are introduced, discussed, and compared.

Siebenhaar, A.↗
NASA NTRS1998

The Role of the Strutjet Engine in New Global and Space Markets

The Strutjet, discussed in previous IAF papers, was originally introduced as an enabling propulsion concept for single stage to orbit applications. Recent design considerations indicate that this systems also provides benefits supportive of other commercial non-space applications. This paper describes the technical progress of the Strutjet since 1997 together with a rationale why Rocket Based Combined Cycle Engines in general, and the Strutjet in particular, lend themselves uniquely to systems having the ability to expand current space and open new global "rapid delivery" markets. During this decade, Strutjet technology has been evaluated in over 1000 tests. Its design maturity has been continuously improved and desired features, like simple variable geometry and low drag flowpath resulting in high performance, are verified. In addition, data is now available which allows the designer, who is challenged to maximize system operability and economic feasibility, to choose between hydrogen or hydrocarbon fuels for these application. The ability exists now to apply this propulsion system to various vehicles with a multitude of missions. In this paper, the previously presented earth-to-orbit hydrogen powered vehicle is up3ated and another vehicle, specifically designed for rapid point-to-point delivery, is introduced and discussed. High payoff propulsion technologies required for these vehicles are identified and laid out in a roadmap spanning over the next decade.

Siebenhaar, A.↗
DOE OSTI2021

Design of high-deflection foils MHK applications - FEA models - Helical turbines

The Ocean Renewable Power Company's (ORPC's) goal is to design, develop, and test hydrofoils with large deflections. The effects of the deflections on cross-flow turbine performance would be evaluated in order to inform design considerations for full-scale water turbines and other marine hydrokinetic devices. FEA models - NASTRAN Helical foil turbines tested at UNH tow tank Glass and carbon composite material properties Loads derived from CFD models

16 TIDAL AND WAVE POWER↗
DOE OSTI2019

Hurricane Eyewall Winds and Structural Response of Wind Turbines

This paper describes the analysis of a wind turbine and support structure subject to simulated hurricane wind fields. The hurricane wind fields, which result from a Large Eddy Simulation of a hurricane, exhibit features such as very high gust factors (> 1.7), rapid direction changes (30 degrees in 30 sec) and substantial veer. Wind fields including these features have not previously been used in an analysis of a wind turbine and their effect on structural loads may be an important driver of enhanced design considerations. With a focus on blade root loads and tower base loads, the simulations show that these features of hurricane wind fields can lead to loads that are substantially in excess of those that would be predicted were wind fields with equally high mean wind speeds but without associated direction change and veer used in the analysis. This result, if further verified for a range of hurricane and tropical storm simulations, should provide an impetus for revisiting design standards.

17 WIND ENERGY↗
DOE OSTI2025

Comparison of tungsten versus molybdenum for double shell capsules using machine learning design optimization

Double shell targets are an alternative ignition platform for inertial confinement fusion. One design consideration for double shell targets is the choice of inner shell material to help trap radiation emitted by the hot fuel to aid ignition. Materials such as molybdenum and tungsten are of interest for the inner shell layer of the targets. While molybdenum has a lower density that could inhibit instability growth and allow for radiography and code benchmarking, tungsten has a higher density that could provide more compression and confinement. These tradeoffs have been explored using optimized designs for each material. Our previous work [Vazirani et al., “Coupling 1D xRAGE simulations with machine learning for graded inner shell design optimization in double shell capsules,” Phys. Plasmas 28, 122709 (2021); Vazirani et al., “Coupling multi-fidelity xRAGE with machine learning for graded inner shell design optimization in double shell capsules,” Phys. Plasmas 30, 062704 (2023); and Vazirani et al., “Bayesian batch optimization for molybdenum versus tungsten inertial confinement fusion double shell target design,” Stat. Anal. Data Min. 17, e11698 (2024)] resulted in a multi-fidelity Bayesian optimization framework to find yield-optimized double shell target geometries. By leveraging simulations of varying fidelities (one-dimensional and two-dimensional) to inform one another, the multi-fidelity optimization was able to optimize a design in the highest fidelity with significantly fewer simulations than would be used in a systematic parameter scan. In this work, we apply the multi-fidelity Bayesian optimization to explore the optimized designs of double shell targets with molybdenum and tungsten inner shells as well as the physics producing the high performing implosions. A physics exploration of all the simulations used in this study shows trends in designs that contribute to high yields, ion temperatures, and fuel areal densities. Comparison of molybdenum and tungsten simulations shows that they can produce similar implosion conditions with different geometries, which would be important to study in experiments. Graded density layers produce varying performances with the two materials but continue to be of interest for future studies along with studies of doped inner shell materials and applied surface roughness.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2007

Kilopixel Pop-Up Bolometer Arrays for the Atacama Cosmology Telescope

The recently deployed Atacama Cosmology Telescope (ACT) anticipates first light on its kilopixel array of close-packed transition-edge-sensor bolometers in November of 2007. The instrument will represent a full implementation of the next-generation, large format arrays for millimeter wave astronomy that use superconducting electronics and detectors. Achieving the practical construction of such an array is a significant step toward producing advanced detector arrays for future SOFIA instruments. We review the design considerations for the detector array produced for the ACT instrument. The first light imager consists of 32 separately instrumented 32-channel pop-up bolometer arrays (to create a 32x32 filled array of mm-wave sensors). Each array is instrumented with a 32-channel bias resistor array, Nyquist filter array, and time-division SQUID multiplexer. Each component needed to be produced in relatively large quantities with suitable uniformity to meet tolerances for array operation. An optical design was chosen to maximize absorption at the focal plane while mitigating reflections and stray light. The pop-up geometry (previously implemented with semiconducting detectors and readout on the SHARC II and HAWC instruments) enabled straightforward interface of the superconducting bias and readout circuit with the 2D array of superconducting bolometers. The array construction program balanced fabrication challenges with assembly challenges to deliver the instrument in a timely fashion. We present some of the results of the array build and characterization of its performance.

Chervenak, J. A.↗
DOE OSTI2015

Efficient Parallel Discrete Event Simulation on Cloud/Virtual Machine Platforms

Cloud and Virtual machine (VM) technologies present new challenges with respect to performance and monetary cost in executing parallel discrete event simulation (PDES) applications. Due to the introduction of overall cost as a metric, the traditional use of the highest-end computing configuration is no longer the most obvious choice. Moreover, the unique runtime dynamics and configuration choices of Cloud and VM platforms introduce new design considerations and runtime characteristics specific to PDES over Cloud/VMs. Here, an empirical study is presented to guide an understanding of the dynamics, trends, and trade-offs in executing PDES on Cloud/VM platforms. Performance and cost measures obtained from multiple PDES applications executed on the Amazon EC2 Cloud and on a high-end VM host machine reveal new, counterintuitive VM--PDES dynamics and guidelines. One of the critical aspects uncovered is the fundamental mismatch in hypervisor scheduler policies designed for general cloud workloads versus the virtual time ordering needed for PDES workloads. This insight is supported by experimental data revealing the gross deterioration in PDES performance traceable to VM scheduling policy. To overcome this fundamental problem, the design and implementation of a new deadlock-free scheduler algorithm are presented, optimized specifically for PDES applications on VMs. The scalability of our scheduler has been tested up to 128 VMs multiplexed on 32 cores, showing significant improvement in the runtime relative to the default Cloud/VM scheduler. The observations, algorithmic design, and results are timely for emerging cloud/VM-based installations, highlighting the need for PDES-specific support in high performance discrete event simulations on Cloud/VM platforms.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Boosting Cell Performance of LiNi 0.8 Co 0.15 A 0.05 O 2 via Surface Structure Design

Although the high energy density and environmental benignancy of LiNi 0.8 Co 0.15 A 0.05 O 2 (NCA) holds promise for use as cathode material in Li-ion batteries, present low rate capabilities, and fast capacity fade limit its broad commercial applications. Here, it is reported that surface modification of NCA cathode (R-3m) with 5 nm-thick nanopillar layers and Fm-3m structures significantly improves electrode structure, morphology, and electrochemical performance. The formation of nanopillar layers increases cycling and working voltage stability of NCA by shielding the host material from hydrofluoric acid and improves structural stability with the electrolyte. The modified NCA cathode exhibits an enhanced 89% capacity retention at a rate of 1 C over that of pristine NCA (75.2%) after 150 cycles and effectively suppresses working voltage fade (a drop of 0.025 V after 300 cycles) during repeated charge-discharge cycles. In addition, the diffusion barrier of Li ions in NCA crystals at 0.80 V is noticeably smaller than that of Li ions in pristine NCA (0.87 eV). These findings demonstrate that this unique surface structure design considerably enhances cycle and rate performance of NCA, which has potential applications in other Ni-rich layered cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2014

Diagnostic systems in DEMO: Engineering design issues

The diagnostic systems of DEMO that are mounted on or near the torus, whether intended for the monitoring and control functions of the engineering aspects or the physics behaviour of the machine, will have to be designed to suit the hostile nuclear environment. This will be necessary not just for their survival and correct functioning but also to satisfy the pertinent regulatory bodies, especially where any of them relate to machine protection or the prevention or mitigation of accidents foreseen in the safety case. This paper aims to indicate the more important of the reactor design considerations that are likely to apply to diagnostics for DEMO, drawn from experience on JET, the provisions in hand for ITER and modelling results for the wall erosion and neutron damage effects in DEMO.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

PCB-on-DBC GaN Power Module Design with High-Density Integration and Double-Sided Cooling

Lateral gallium nitride (GaN) high-electron-mobility transistors (HEMTs) present better electrical characteristics compared to silicon or silicon carbide devices such as high switching speed and low gate charge, but also present additional challenges on the module design. Here, this paper discusses a high-density GaN power module with double-sided cooling, low inductance, on-package decoupling capacitors, and integrated gate drivers. The GaN dies as well as the gate drive are sandwiched between the printed circuit board (PCB) and direct bonded copper (DBC) substrate to achieve compact loop and double-sided cooling effect. Design considerations and thermal performance are analyzed. A module assembly procedure is presented utilizing the layer-by-layer attachment process. Finally, a 2.7 cm x 1.8 cm half-bridge GaN power module is fabricated and tested, achieving a low power-loop inductance of 1.03 nH, and the overshoot voltage of the switching waveform is less than 5% under a 400-V/25-A double-pulse test. The thermal resistance is 0.32 K/W, verified by simulation and experimental results. The design and assembly process can be generalized and applied to high power applications to achieve high power density and high performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Comparing Pr 3+ and Nd 3+ for deactivating the Er 3+ : 4 I 13/2 level in lanthanum titanate glass

Erbium lanthanum titanate glasses were prepared by levitation melting for the spectroscopic study of ways to promote the mid-infrared fluorescence. Two series of heavily erbium doped glasses (15 wt%) were prepared with the addition of either Pr 3+ or Nd 3+ in amounts relative to Er 3+ of 0.05, 0.1, and 0.2. Both ions quench the lower Er 3+ laser level with the Pr 3+ doing so more rapidly. Although high co-dopant concentrations result in higher energy transfer, as clearly evidenced in upconversion and downconversion fluorescence measurements, the mid-infrared lifetime also suffers a reduction and, therefore, a balance must be struck in the co-dopant concentration. Lifetime and spectral measurements indicate that, at a fixed relative co-dopant amount, Pr 3+ is more effective than Nd 3+ at removing the bottleneck of the Er 3+ 4 I 13/2 level. Moreover, consideration of the lifetimes alongside the absorption data of the individual ions indicates that despite the large absorption cross-section of Nd 3+ at 808 nm, the concentration needed to yield more absorbed power than utilizing direct 976 nm excitation of Er 3+ results in unfavorable lifetimes of the mid-infrared transition. In the end, Pr 3+ prevails as the superior co-dopant in terms of the effects on fluorescence lifetimes as well as potential laser system design considerations. In a unique self-doping approach, a reducing melt atmosphere of Ar instead of O 2 creates a small fraction of Ti 3+ . In 5Er 2 O 3 -12La 2 O 3 -83TiO 2 glass, the presence of Ti 3+ quenches the 4 I 13/2 emission about 2.6 times more than the 4 I 11/2 when lifetimes are compared to an O 2 melt environment. As an additional means of increasing the mid-infrared emission, the effect of temperature on the mid- and near- infrared lifetimes of a lightly doped lanthanum titanate composition is investigated between 77-300 K. The mid-infrared lifetime increases by ∼30% while the near-infrared lifetime increases by ∼10%, which suggests in addition to co-doping, active cooling of the gain media will further enhance performance.

Materials Science↗
DOE OSTI2018

Optimization of concentrator photovoltaic solar cell performance through photonic engineering

The goal of this program was to incorporate two new and innovative design concepts into the design and production of CPV cells that have near zero added cost, yet significantly increase the operational efficiency of CPV modules. The program focused developing luminescent coupling effects and radiative cooling layers to increase efficiency and suppress CPV module power losses due to spectral variations and heating. The major results of the program were: 1) The optics of three commercial refractive (Fresnel) concentrators were characterized and prevent application of radiative cooling concepts due to strong mid-IR absorption (4-12µm) required to effectively radiate blackbody radiation from the cells and provide cooling. Investigation of alternative materials for the concentrator lenses produced only undesirable options—materials with reasonable mid-IR transmission for cooling only had about 30-40 visible transmission, thus reducing incident sunlight by >50%. While our investigation was somewhat limited, our work suggests that the only viable concentrator system that can incorporate radiative cooling utilizes reflective optics. 2) With limited ability to test high concentration CPV cells (requires outdoor testing), we acquired both semi-crystalline and crystalline Si cells and tested them in our outdoor facility and demonstrated 4°C cooling using a simple silica layer coating on the cells. 3) Characterizing Si cells in the IR associated with radiative cooling, we observed very significant near-IR absorption that increases the cell operating temperature by a similar amount, 4-5°C. By appropriate surface layer design, one can produce a layer that is highly reflective in the near-IR (1.5-4µm) and highly emissive in the mid-IR (5-15µm), thus reducing cell operational temperature by 10°C and increasing efficiency by ~1% absolute. The radiative cooling effect in c-Si solar cells might be further improved by providing a higher thermal conductive elastomer for securing the cover glass on top of the AR-coating. Since it was never imagined that the front surface would provide any cooling for solar cells, thermal conductivity of this elastomer was never a design consideration, but, improving the conductivity could decrease cell temperature by another 3-4°C. The combined effect could be an ~1.5% absolute increase in cell and module efficiency, a very significant improvement. 4) Developed a numerical model to explore dependence of luminescent coupling efficiency over a broad range of operating conditions. We developed a novel method and facility to experimentally measure the luminescent coupling that can be used to confirm the dependence of luminescent coupling on multi-junction cell design parameters.

14 SOLAR ENERGY↗
NASA NTRS1992

Progress on ten-meter optical receiver telescope

A ten-meter hexagonally segmented Cassegrain optical telescope is being considered at the Jet Propulsion Laboratory for use as a research and development facility for optical communications technology. The goal of the study is to demonstrate technology which can eventually be used to develop a network of such telescopes to continuously track and communicate with the spacecraft. Hence, the technology has to be economical enough to allow replication for a ground or space based network. As we need to collect signal photons only, the telescope cost can be substantially reduced by accepting lower image quality. An important design consideration for the telescope is its ability to look very close to the sun. The telescope for optical communications must function during the daytime. Indeed, for some planetary missions it may be necessary that the system be capable of looking within a few degrees of the sun. To enable this, a unique sunshade consisting of hexagonal tubes in precise alignment with the mirror segments has been proposed which will also serve as the support for the secondary. Recent progress on the design and analysis of such an optical reception station is discussed here.

Shaik, Kamran↗
DOE OSTI2025

Technology Case Study: Economic, Sustainability, and Deployment Considerations for Sustainable Aviation Fuels Produced via Lignocellulosic Sugar Catalysis

This report presents a technology case study reflecting one exemplary representative pathway for the conversion of lignocellulosic sugars to sustainable aviation fuels (SAF) via aqueous phase reforming (APR) catalysis, considered within a broader integrated biorefinery framework based on biochemical processing operations. While far from the only option for converting sugars to SAF, this pathway was selected as a case study here based on its relatively high technology maturity and simplistic processing approach (avoiding complex separations or other equipment scalability challenges), coupled with the potential for high fuel yields and favorable costs/carbon intensities with opportunities for further near-term optimization. The report considers key process integration and engineering design considerations for a modeled hypothetical, nth-plant commercial biorefinery, reflecting a number of processing options and parameters envisioned to be achievable as future goals. Resultant outputs from Aspen Plus process simulations are evaluated through techno-economic and life cycle analyses (TEA and LCA), including implications for marginal cost of CO2 abatement and inclusion of currently-applicable policy incentives. Moving beyond base case configurations, a number of alternative scenarios are also evaluated for their ability to further improve economics, greenhouse gas (GHG) emissions, and marginal cost of abatement, highlighting a path to achieve deep decarbonization goals of more than 70% GHG reduction for SAF (with the potential to reach net-negative carbon intensities in some cases) under reasonable fuel production costs. The report also highlights future opportunities and gaps for further research on this technology pathway.

09 BIOMASS FUELS↗
NASA NTRS2014

A Cryogenic Infrared Calibration Target

A compact cryogenic calibration target is presented that has a peak diffuse reflectance, R < or = 0.003, from 800 to 4800/cm (12 − 2 microns ). Upon expanding the spectral range under consideration to 400-10,000/ cm−1 (25 − 1 microns) the observed performance gracefully degrades to R < or = 0.02 at the band edges. In the implementation described, a high-thermal-conductivity metallic substrate is textured with a pyramidal tiling and subsequently coated with a thin lossy dielectric coating that enables high absorption and thermal uniformity across the target. The resulting target assembly is lightweight, has a low-geometric profile, and has survived repeated thermal cycling from room temperature to approx.4 K. Basic design considerations, governing equations, and test data for realizing the structure described are provided. The optical properties of selected absorptive materials-Acktar Fractal Black, Aeroglaze Z306, and Stycast 2850 FT epoxy loaded with stainless steel powder-are characterized and presented

dielectric coating↗
DOE OSTI2013

The lead-glass electromagnetic calorimeters for the magnetic spectrometers in Hall C at Jefferson Lab

The electromagnetic calorimeters of the various magnetic spectrometers in Hall C at Jefferson Lab are presented. For the existing HMS and SOS spectrometers design considerations, relevant construction information, and comparisons of simulated and experimental results are included. The energy resolution of the HMS and SOS calorimeters is better than $\sigma/E \sim 6%/\sqrt E $, and pion/electron ($\pi/e$) separation of about 100:1 has been achieved in energy range 1 -- 5 GeV. Good agreement has been observed between the experimental and simulated energy resolutions, but simulations systematically exceed experimentally determined $\pi^-$ suppression factors by close to a factor of two. For the SHMS spectrometer presently under construction details on the design and accompanying GEANT4 simulation efforts are given. The anticipated performance of the new calorimeter is predicted over the full momentum range of the SHMS. Good electron/hadron separation is anticipated by combining the energy deposited in an initial (preshower) calorimeter layer with the total energy deposited in the calorimeter.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗