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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

CLEAR: Boosted Ly alpha Transmission of the Intergalactic Medium in UV-bright Galaxies

Reionization is an inhomogeneous process, thought to begin in small ionized bubbles of the intergalacticmedium (IGM) around overdense regions of galaxies. Recent Lyman-alpha (Lyα) studies during the epochof reionization show growing evidence that ionized bubbles formed earlier around brighter galaxies, suggest-ing higher IGM transmission of Lyαfrom these galaxies. We investigate this problem using IR slitless spec-troscopy from the Hubble Space Telescope (HST) Wide-Field Camera 3 (WFC3) G102 grism observations of148 galaxies selected via photometric redshifts at6.0< z <8.2. These galaxies have spectra extracted fromthe CANDELS LyαEmission at Reionization (CLEAR) survey. We combine the CLEAR data for 275 galaxieswith the Keck/DEIMOS+MOSFIRE dataset from the Texas Spectroscopic Search for LyαEmission at the Endof Reionization Survey. We then constrain the Lyαequivalent-width (EW) distribution at6.0< z <8.2, whichis described by an exponential form,dN/dEW∝exp(-EW)/W0, with the characteristice-folding scale width(W0). We confirm a significant drop of the Lyαstrength (orW0) atz >6. Furthermore, we compare the redshiftevolution ofW0between galaxies at different UV luminosities. The UV-bright (MUV<−21, orLUV> L∗)galaxies show weaker evolution with a decrease of 0.4 (±0.2) dex inW0atz >6while UV-faint (MUV>−21,orLUV< L∗) galaxies exhibit a significant drop by a factor of 0.7-0.8 (±0.2) dex inW0fromz <6toz >6.Our results add to the accumulating evidence that UV-bright galaxies exhibit boosted Lyαtransmission in theIGM, suggesting that reionization completes sooner in regions proximate to galaxies of higher UV luminosity.

Intae Jung↗
DOE OSTI2015

Integrated Charger with Wireless Charging and Boost Function for PHEV and EV Applications

Integrated charger topologies that have been researched so far with dc-dc converters and the charging functionality have no isolation in the system. Isolation is an important feature that is required for user interface systems that have grid connections and therefore is a major limitation that needs to be addressed along with the integrated functionality. The topology proposed in this paper is a unique and a first of its kind topology that integrates a wireless charging system and the boost converter for the traction drive system. The new topology is also compared with an on-board charger system from a commercial electric vehicle (EV). The ac-dc efficiency of the proposed system is 85.05% and the specific power and power density of the onboard components is ~455 W/kg and ~302 W/ .

integrated charger↗
DOE OSTI2016

Boosting Manufacturing through Modular Chemical Process Intensification

Manufacturing USA's Rapid Advancement in Process Intensification Deployment Institute will focus on developing breakthrough technologies to boost domestic energy productivity and energy efficiency by 20 percent in five years through manufacturing processes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Co-Optimization of Fuels & Engines (Co-Optima) Initiative: Recent Progress on Light-Duty Boosted Spark-Ignition Fuels/Engines

This presentation reports recent progress on light-duty boosted spark-ignition fuels/engines being developed under the Co-Optimization of Fuels and Engines initiative (Co-Optima). Co-Optima is focused on identifying fuel properties that optimize engine performance, independent of composition, allowing the market to define the best means to blend and provide these fuels. However, in support of this, we are pursuing a systematic study of blendstocks to identify a broad range of feasible options, with the objective of identifying blendstocks that can provide target ranges of key fuel properties, identifying trade-offs on consistent and comprehensive basis, and sharing information with stakeholders.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

Distributed control system for parallel-connected DC boost converters

The disclosed invention is a distributed control system for operating a DC bus fed by disparate DC power sources that service a known or unknown load. The voltage sources vary in v-i characteristics and have time-varying, maximum supply capacities. Each source is connected to the bus via a boost converter, which may have different dynamic characteristics and power transfer capacities, but are controlled through PWM. The invention tracks the time-varying power sources and apportions their power contribution while maintaining the DC bus voltage within the specifications. A central digital controller solves the steady-state system for the optimal duty cycle settings that achieve a desired power supply apportionment scheme for a known or predictable DC load. A distributed networked control system is derived from the central system that utilizes communications among controllers to compute a shared estimate of the unknown time-varying load through shared bus current measurements and bus voltage measurements.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2017

Inclusive Search for Boosted Higgs Bosons Using H$ \rightarrow \mathrm{b\overline{b}}$ Decays with the CMS Experiment

We present the first search for the standard model Higgs boson (H) produced with large transverse momentum ($\mathrm{p_{T}}$) via gluon fusion and decaying to a bottom quark-antiquark pair ($\mathrm{b\overline{b}}$). The search is performed using a data set of pp collisions at $\sqrt{s}=13$ TeV collected with the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{\mathrm{-1}}$. A highly Lorentz-boosted Higgs boson decaying to $\mathrm{b\overline{b}}$ is reconstructed as a single, large radius jet and is identified using jet substructure and dedicated b tagging techniques. The method is validated with the first observation of the Z$\rightarrow\mathrm{b\overline{b}}$ process in the single-jet topology, with a local significance of 5.1 standard deviations (5.8 expected).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Automated Proton Track Identification in MicroBooNE Using Gradient Boosted Decision Trees

MicroBooNE is a liquid argon time projection chamber (LArTPC) neutrino experiment that is currently running in the Booster Neutrino Beam at Fermilab. LArTPC technology allows for high-resolution, three-dimensional representations of neutrino interactions. A wide variety of software tools for automated reconstruction and selection of particle tracks in LArTPCs are actively being developed. Short, isolated proton tracks, the signal for low- momentum-transfer neutral current (NC) elastic events, are easily hidden in a large cosmic background. Detecting these low-energy tracks will allow us to probe interesting regions of the proton's spin structure. An effective method for selecting NC elastic events is to combine a highly efficient track reconstruction algorithm to find all candidate tracks with highly accurate particle identification using a machine learning algorithm. We present our work on particle track classification using gradient tree boosting software (XGBoost) and the performance on simulated neutrino data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Delayed boost of driver output signals

According to examples, an apparatus may include a field effect transistor (FET), a driver to receive an input signal and to output a driver output signal, and a gate to receive the input signal. The apparatus may also include a delay element to receive the driver output signal and to output a delayed signal to the gate after a delay from receipt of the driver output signal, in which the gate is to output a gate output signal to the FET in response to receipt of the input signal and the delayed signal, and in which receipt of the gate output signal by the FET drives the FET to provide a boost to the driver output signal.

42 ENGINEERING↗
DOE OSTI2017

Boosting Thermal Management & Reliability of Vehicle Power Electronics

Electric vehicles rely heavily on power electronics—including inverters, converters, and chargers—to control the flow of electricity between the battery, the motor, and other powertrain components. NREL is helping boost the performance of power electronics components and systems, while driving down size, weight, and cost. In electric vehicles, these components need to operate at higher temperatures, voltages, switching frequencies, and power conversion efficiencies. That’s where NREL’s thermal management and reliability research comes in.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2024

Next Generation High Efficiency Boosted Engine Concept

This report summarizes a collaborative research project between Ford Motor Company, FEV North America, and Oak Ridge National Laboratory to develop a next-generation, high-efficiency, boosted spark-ignited engine. The goal was to achieve a 23% improvement in fuel economy and a 15% reduction in engine weight compared to a 2016 Ford F150. The team utilized advanced technologies including a high compression ratio, cooled exhaust gas recirculation (EGR), early intake valve closing, and a novel active pre-chamber ignition system. The final engine prototype met the fuel economy goal and demonstrated a 4.3% weight reduction, with further opportunities identified to reach the full 15% target.

Fuel economy↗
DOE OSTI2025

Evaluating Chemical Kinetics Predictions for Propane Using 3-D and 0-D Models in a Boosted Spark-Ignited Engine

Propane has been shown to be a promising alternative fuel to reduce emissions while simultaneously achieving high efficiencies in medium- and heavy-duty engines. These high-power density applications require boosted engines which, combined with high compression ratio, can lead to auto-ignition and knock. While three-dimensional (3-D) computational fluid dynamics (CFD) models are often used for resolving the complex fluid flow in engines, these models can become computationally expensive when simulating detailed chemical kinetics. Likewise, zero-dimensional (0-D) models are computationally concise enough for kinetics development, but lack any flow-field information which governs the flame propagation processes in spark ignition (SI) engines. This work presents a comprehensive comparison between 3-D and 0-D closed cycle simulations at knocking conditions in a high compression ratio high stroke-to-bore ratio propane engine. In order to initialize the flow-field for the 3-D closed cycle (intake valve closing, (IVC) to exhaust valve opening, (EVO)) simulation, a motored multi-cycle 3-D model was run using Converge to create a map at IVC, reducing the computational time. The map allowed a non-homogeneous 3-D closed cycle simulation to be satisfactorily validated against experiments, while a homogeneous case using only the turbulence field mapping was also simulated, mimicking 0-D modeling. The 3-D simulations were used to prescribe the initial conditions (e.g., IVC thermodynamics, speciation, burn-rate profile) for a 2-zone 0-D SI engine model in Chemkin Pro for both cases. It was found that 2-zone 0-D modeling underpredicted the knock onset timing, likely due to the lack of thermal stratification in the unburned gas region. Future work will carry multi-zone 0-D modeling to capture the fuel auto-ignition in the unburned region.

Douvry-Rabjeau, Julien [Oakland University, Roches↗
DOE OSTI2020

Boosting the Performance of Plug-and-Play Priors via Denoiser Scaling

Plug-and-play priors (PnP) is an image reconstruction framework that utilizes an image denoiser as an imaging prior. Unlike traditional regularized inversion, PnP does not require the prior to be expressible in the form of a regularization function. This flexibility enables PnP algorithms to exploit the most effective image denoisers, leading to their state-of-the-art performance in various imaging tasks. However, many powerful denoisers, such as the ones based on convolutional neural networks (CNNs), do not have tunable parameters that would allow controlling their influence within PnP. To address this issue, in this paper, we introduce a scaling parameter that adjusts the magnitude of the denoiser input and output. We theoretical justify the denoiser scaling from the perspectives of proximal optimization, statistical estimation, and consensus equilibrium. Finally, we provide numerical experiments demonstrating the ability of denoiser scaling to systematically improve the performance of PnP for denoising CNN priors that do not have explicitly tunable parameters.

Boosting↗
DOE OSTI2014

Solar High Temperature Water-Splitting Cycle with Quantum Boost

A sulfur family chemical cycle having ammonia as the working fluid and reagent was developed as a cost-effective and efficient hydrogen production technology based on a solar thermochemical water-splitting cycle. The sulfur ammonia (SA) cycle is a renewable and sustainable process that is unique in that it is an all-fluid cycle (i.e., with no solids handling). It uses a moderate temperature solar plant with the solar receiver operating at 800°C. All electricity needed is generated internally from recovered heat. The plant would operate continuously with low cost storage and it is a good potential solar thermochemical hydrogen production cycle for reaching the DOE cost goals. Two approaches were considered for the hydrogen production step of the SA cycle: (1) photocatalytic, and (2) electrolytic oxidation of ammonium sulfite to ammonium sulfate in aqueous solutions. Also, two sub-cycles were evaluated for the oxygen evolution side of the SA cycle: (1) zinc sulfate/zinc oxide, and (2) potassium sulfate/potassium pyrosulfate. The laboratory testing and optimization of all the process steps for each version of the SA cycle were proven in the laboratory or have been fully demonstrated by others, but further optimization is still possible and needed. The solar configuration evolved to a 50 MW(thermal) central receiver system with a North heliostat field, a cavity receiver, and NaCl molten salt storage to allow continuous operation. The H2A economic model was used to optimize and trade-off SA cycle configurations. Parametric studies of chemical plant performance have indicated process efficiencies of ~20%. Although the current process efficiency is technically acceptable, an increased efficiency is needed if the DOE cost targets are to be reached. There are two interrelated areas in which there is the potential for significant efficiency improvements: electrolysis cell voltage and excessive water vaporization. Methods to significantly reduce water evaporation are proposed for future activities. Electrolysis membranes that permit higher temperatures and lower voltages are attainable. The oxygen half cycle will need further development and improvement.

08 HYDROGEN↗