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At least 379 records · Page 21

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DOE OSTI2026

Characterizing electrical demand and load diversity of low-power water and space heating appliances in US homes

Home renovation and remodeling projects can involve costly and time consuming electrical infrastructure upgrades at the household level. From the grid perspective they also lead to costly replacement of local infrastructure, such as transformers, and can add stress to the grid at peak times. The emergence of innovative, power-efficient household appliances offers a way to minimize these problems. These appliances are designed for lower power consumption, simplifying installation through standard plug-in connections, reducing the need for new electric circuits/panels/service, and minimizing the peak power demand for the home. Key examples include low-power heat pump water heaters (HPWHs) and cold climate window heat pumps that operate on standard 120V outlets. To assess the real-world impact of these solutions, we compiled and analyzed power metering data from several US field studies. This data provides insights into the effects on peak power demand of selecting lower-power appliances. Our analysis focuses on several key metrics, including the maximum power demand of individual appliances, their operational runtime, continuous operation and load diversity. While individual low-power 120V space and water heating appliances offer significant peak demand reductions compared to 240V heat pump or resistance alternatives, their longer runtimes might increase the likelihood of operation during whole-dwelling peak events, albeit at lower power levels.

Less, Brennan↗

DOE OSTI2022

Non-trivial symmetries in quantum landscapes and their resilience to quantum noise

Very little is known about the cost landscape for parametrized Quantum Circuits (PQCs). Nevertheless, PQCs are employed in Quantum Neural Networks and Variational Quantum Algorithms, which may allow for near-term quantum advantage. Such applications require good optimizers to train PQCs. Recent works have focused on quantum-aware optimizers specifically tailored for PQCs. However, ignorance of the cost landscape could hinder progress towards such optimizers. In this work, we analytically prove two results for PQCs: (1) We find an exponentially large symmetry in PQCs, yielding an exponentially large degeneracy of the minima in the cost landscape. Alternatively, this can be cast as an exponential reduction in the volume of relevant hyperparameter space. (2) We study the resilience of the symmetries under noise, and show that while it is conserved under unital noise, non-unital channels can break these symmetries and lift the degeneracy of minima, leading to multiple new local minima. Based on these results, we introduce an optimization method called Symmetry-based Minima Hopping (SYMH), which exploits the underlying symmetries in PQCs. Our numerical simulations show that SYMH improves the overall optimizer performance in the presence of non-unital noise at a level comparable to current hardware. Overall, this work derives large-scale circuit symmetries from local gate transformations, and uses them to construct a noise-aware optimization method.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2016

Single-cell sequencing of Thiomargarita reveals genomic flexibility for adaptation to dynamic redox conditions

Large, colorless sulfur-oxidizing bacteria (LSB) of the family Beggiatoaceae form thick mats at sulfidic sediment surfaces, where they efficiently detoxify sulfide before it enters the water column. The genus Thiomargarita harbors the largest known free-living bacteria with cell sizes of up to 750 μm in diameter. In addition to their ability to oxidize reduced sulfur compounds, some Thiornargarita spp. are known to store large amounts of nitrate, phosphate and elemental sulfur internally. To date little is known about their energy yielding metabolic pathways, and how these pathways compare to other Beggiatoaceae . Here, we present a draft single-cell genome of a chain-forming " Candidatus Thiomargarita nelsonii Thio36", and conduct a comparative analysis to five draft and one full genome of other members of the Beggiatoaceae . " Ca . T. nelsonii Thio36" is able to respire nitrate to both ammonium and dinitrogen, which allows them to flexibly respond to environmental changes. Genes for sulfur oxidation and inorganic carbon fixation confirmed that " Ca . T. nelsonii Thio36" can function as a chemolithoautotroph. Carbon can be fixed via the Calvin-Benson-Bassham cycle, which is common among the Beggiatoaceae . In addition we found key genes of the reductive tricarboxylic acid cycle that point toward an alternative CO 2 fixation pathway. Surprisingly, " Ca . T. nelsonii Thio36" also encodes key genes of the C2-cycle that convert 2-phosphoglycolate to 3-phosphoglycerate during photorespiration in higher plants and cyanobacteria. Moreover, we identified a novel trait of a flavin-based energy bifurcation pathway coupled to a Na + -translocating membrane complex (Rnf). The coupling of these pathways may be key to surviving long periods of anoxia. As other Beggiatoaceae " Ca . T. nelsonii Thio36" encodes many genes similar to those of (filamentous) cyanobacteria. In conclusion, the genome of " Ca . T. nelsonii Thio36" provides additional insight into the ecology of giant sulfur-oxidizing bacteria, and reveals unique genomic features for the Thiomargarita lineage within the Beggiatoaceae .

"Candidatus Thiomargarita nelsonii"↗

DOE OSTI2021

Portuguese Wood Pellets Market: Organization, Production and Consumption Analysis

Wood pellets are a form of energy that can be seen as an alternative to fossil fuels, thus contributing to the reduction of greenhouse gas emissions. In other words, wood pellets can be considered a solution contributing to the mitigation of climate change. The use of wood pellets has grown significantly in recent years, with different markets emerging, such as Portugal, both from production and consumption perspectives. The wood pellet industry in Portugal began its development about 15 years ago, with the companies installed in the country initially almost exclusively dedicated to the production of wood pellets for export to central and northern European markets. However, over the years, the domestic market, initially considered insignificant, began to develop; it recently reached a considerable consuming share of the national production. This study presents an analysis of the Portuguese wood pellet market using data collected on the sector, and specifically on producers and consumers. The information was gathered using surveys presented directly to consumers and producers and through interviews with other stakeholders in the sector. From the analysis of the information, it was possible to understand the market’s dynamics, its current evolution and its prospects for the upcoming years, since it can already be considered mature and consolidated.

Nunes, Leonel J. R. (ORCID:0000000154048163)↗

NASA NTRS1976

Re-examination of compliant wall experiments in air with water substrates

A possible alternative explanation is proposed for compliant wall drag reductions measured in previous investigations. Standing waves were observed to form on the surfaces of compliant wall models in air with water substrates as the freestream velocity was increased from 15 to 30 m/s. These waves resembled sine waves with half of the wave protruding over the upstream portion of the model and the other half being recessed over the downstream end of the model. These data coupled with results of recent drag reduction experiments suggest that standing waves could have caused a shift in the model center of gravity creating a bending moment that was interpreted as a reduction in the skin friction drag.

Hefner, J. N.↗

NASA NTRS1977

Fuel conservation merits of advanced turboprop transport aircraft

The advantages of a propfan powered aircraft for the commercial air transportation system were assessed by the comparison with an equivalent turbofan transport. Comparisons were accomplished on the basis of fuel utilization and operating costs, as well as aircraft weight and size. Advantages of the propfan aircraft, concerning fuel utilization and operating costs, were accomplished by considering: (1) incorporation of propfan performance and acoustic data; (2) revised mission profiles (longer design range and reduction in; and cruise speed) (3) utilization of alternate and advanced technology engines.

Revell, J. D.↗

NASA NTRS1984

Polycrystalline Silicon Sheets for Solar Cells by the Improved Spinning Method

Cost reduction of silicon materials in the photovoltaic program of materials was examined. The current process of producing silicon sheets is based entirely on the conventional Czochralski ingot growth and wafering used in the semiconductor industry. The current technology cannot meet the cost reduction demands for producing low cost silicon sheets. Alternative sheet production processes such as unconventional crystallization are needed. The production of polycrystalline silicon sheets by unconventional ingot technology is the casting technique. Though large grain sheets were obtained by this technique, silicon ribbon growth overcomes deficiencies of the casting process by obtaining the sheet directly from the melt. The need to solve difficulties of growth stability and impurity effects are examined. The direct formation process of polycrystalline silicon sheets with large grain size, smooth surface, and sharp edges from the melt with a high growth rate which will yield low cost silicon sheets for solar cells and the photovoltaic characteristics associated with this type of sheet to include an EBIC study of the grain boundaries are described.

Maeda, Y.↗

NASA NTRS1994

Multiple Concurrent Visual-Motor Mappings: Implications for Models of Adaptation

Previous research on adaptation to visual-motor rearrangement suggests that the central nervous system represents accurately only 1 visual-motor mapping at a time. This idea was examined in 3 experiments where subjects tracked a moving target under repeated alternations between 2 initially interfering mappings (the 'normal' mapping characteristic of computer input devices and a 108' rotation of the normal mapping). Alternation between the 2 mappings led to significant reduction in error under the rotated mapping and significant reduction in the adaptation aftereffect ordinarily caused by switching between mappings. Color as a discriminative cue, interference versus decay in adaptation aftereffect, and intermanual transfer were also examined. The results reveal a capacity for multiple concurrent visual-motor mappings, possibly controlled by a parametric process near the motor output stage of processing.

Cunningham, H. A.↗

NASA NTRS2003

Evaluation and Characterization Study of Dual Pulse Laser-Induced Spark (DPLIS) for Rocket Engine Ignition System Application

This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). Laser ignition has been used at MSFC in recent test series to successfully ignite RP1/GOX propellants in a subscale rocket chamber, and other past studies by NASA GRC have demonstrated the use of laser ignition for rocket engines. Despite the progress made in the study of this ignition method, the logistics of depositing laser sparks inside a rocket chamber have prohibited its use. However, recent advances in laser designs, the use of fiber optics, and studies of multi-pulse laser formats3 have renewed the interest of rocket designers in this state-of the-art technology which offers the potential elimination of torch igniter systems and their associated mechanical parts, as well as toxic hypergolic ignition systems. In support of this interest to develop an alternative ignition system that meets the risk-reduction demands of Next Generation Launch Technology (NGLT), characterization studies of a dual pulse laser format for laser-induced spark ignition are underway at MSFC. Results obtained at MSFC indicate that a dual pulse format can produce plasmas that absorb the laser energy as efficiently as a single pulse format, yet provide a longer plasma lifetime. In an experiments with lean H2/air propellants, the dual pulse laser format, containing the same total energy of a single laser pulse, produced a spark that was superior in its ability to provide sustained ignition of fuel-lean H2/air propellants. The results from these experiments are being used to optimize a dual pulse laser format for future subscale rocket chamber tests. Besides the ignition enhancement, the dual pulse technique provides a practical way to distribute and deliver laser light to the combustion chamber, an important consideration given the limitation of peak power that can be delivered through optical fibers. With this knowledge, scientists and engineers at Los Alamos National Laboratory and CFD Research Corporation have designed and fabricated a miniaturized, first-generation optical prototype of a laser ignition system that could be the basis for a laser ignition system for rocket applications. This prototype will be tested at MSFC in future subscale rocket ignition tests.

Osborne, Robin↗

NASA NTRS2005

Pressures in Tumuli: A Study of Tumuli Formation

Tumuli form via localized inflation in surface lava flows. These domed features have widths of 10-20 m, lengths of 10-150 m, and heights of 1-9 m. The axial fracture exposes a brittle crust overlying a ductilely deformed layer. The total crustal thickness is typically less than lm. Tumuli are observed on both terrestrial and martian lava flow surfaces, and provide insight on the flow formation processes and rates. Past studies have estimated the inflation pressure using a bending model for a circular, thin elastic plate, assuming small deflection (Rossi and Gudmundson, 1996). This formulation results in unrealistic pressures for some tumuli. We thus examine alternative models, including those with different shapes, bending of the ductile crust, large deflection, plastic deformation, and thick plate bending. Using the thickness of the ductile crust in the equations for thin, circular plates reduces most pressures to reasonable values. Alternative plate shapes do not cause a significant reduction in inflation pressure. Although the large deflection equations should be applicable based on the plate thickness to tumuli height ratios, they give even less realistic pressures. Tumuli with unrealistic pressures appear to have exceeded the critical bending moment, and have relatively thick crusts, requiring thick plate bending models.

Hansen, James E.↗

NASA NTRS2008

Space Shuttle MMOD Threat Mitigation Techniques

Prior to each shuttle mission, threat assessments are performed to determine the risk of critical penetration, payload bay door radiator tube leak and crew module window replacement from Micrometeoroid and Orbital Debris (MMOD). Mission parameters, such as vehicle attitude, exposure time and altitude are used as inputs for the analysis. Ballistic limit equations, based on hypervelocity impact testing of shuttle materials are used to estimate the critical particle diameters of the outer surfaces of the vehicle. The assessments are performed using the BUMPER computer code at the NASA/JSC Hypervelocity Impact Technology Facility (HITF). The most critical involves the calculation of Loss of Crew and Vehicle (LOCV) risk. An overview of significant MMOD impacts on the Payload Bay Door radiators, wing leading edge reinforced carbon-carbon (RCC) panels and crew module windows will be presented, along with a discussion of the techniques NASA has implemented to reduce the risk from MMOD impacts. This paper will describe on-orbit inspection of the RCC regions and the methods used discern hypervelocity impact damage. Impact damage contingency plans and on-orbit repair techniques will also be discussed. The wing leading edge impact detection system (WLEIDS) and it s role in the reduction of on-orbit risk reduction will be presented. Finally, an analysis of alternative shuttle flight attitudes on MMOD risk will be demonstrated.

Hyde, J. L.↗

NASA NTRS2014

The Max Launch Abort System - Concept, Flight Test, and Evolution

The NASA Engineering and Safety Center (NESC) is an independent engineering analysis and test organization providing support across the range of NASA programs. In 2007 NASA was developing the launch escape system for the Orion spacecraft that was evolved from the traditional tower-configuration escape systems used for the historic Mercury and Apollo spacecraft. The NESC was tasked, as a programmatic risk-reduction effort to develop and flight test an alternative to the Orion baseline escape system concept. This project became known as the Max Launch Abort System (MLAS), named in honor of Maxime Faget, the developer of the original Mercury escape system. Over the course of approximately two years the NESC performed conceptual and tradeoff analyses, designed and built full-scale flight test hardware, and conducted a flight test demonstration in July 2009. Since the flight test, the NESC has continued to further develop and refine the MLAS concept.

Gilbert, Michael G.↗

DOE OSTI2012

ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD

At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a weak base anion single-use resin, ResinTech SIR-700, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently on site, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation and return of resin for regeneration. This resin was installed in Hanford's newest groundwater treatment facility, called 100-DX, which began operations in November, 2010, and used in a sister facility, 100-HX, which started up in September of 2011. This increased chromium treatment capacity to 25 trains (100 vessels). The resin is also being tested in existing facilities that utilize Dowex 21 K for conversion to the new resin. This paper will describe the results of the testing, performance in the facilities, continued optimization in the pump and treat facilities, and the estimated savings and non-tangible benefits of the conversion.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2014

HVOF Thermal Spray TiC/TiB2 Coatings of AUSC Boiler/Turbine Components for Enhanced Corrosion Protection

Supercritical Rankine cycles facilitate the attainment of higher efficiencies and lowered emissions. The high temperatures and enhanced reactivity of supercritical water still pose significant risk of degradation and fatigue from oxidizing, corroding and eroding environment. In addition, ash particulates and unburnt carbon and pyritic sulfur can cause erosion of the surface and thus loss of material. Unburnt carbon and pyritic sulfur may also cause localized reduction sites TiC and TiB2 are suitable coating alternatives on account of the material features such as the high hardness, the high melting point, the high strength, low density and chemical stability required for long-term service. The paper presents the research endeavors to synthesize TiC and TiB2 coatings on existing boiler materials for applications at high temperatures (500 -750 oC) and high pressures (~350 bars) using the HVOF process and to demonstrate the feasibility of these coating to be used in AUSC boilers and turbines.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2019

Developing Publicly Available LCA Guidance, Data, and Tools for Environmental Understanding of Emerging CO2 Utilization Research - LCAXIX

This work was presented at the American Center for Life Cycle Assessment 2019 Conference (LCAXIX) in Tucson, AZ on September 25, 2019. Capturing carbon dioxide (CO2) emissions from power and industrial sources and using that CO2 to make useful products is an emerging area of research that will benefit from a consistent and unbiassed framework like life cycle assessment/analysis (LCA) to understand the environmental impacts and net life cycle GHG reductions compared to the current state of the alternative in the marketplace. In the interest of supporting the creation of useful and consistent LCAs of CO2 utilization projects, the DOE National Energy Technology Laboratory has developed a CO2 utilization LCA toolkit. The primary audience for the toolkit is the group of principal investigators that have been awarded a grant through a DOE Carbon Use and Reuse funding opportunity announcement. However, we believe that there is potential wider application beyond those grant recipients.

Cooney, Gregory↗

DOE OSTI2023

Clean Cities Coalitions: Advancing Affordable, Efficient, and Clean Transportation Fuels and Technologies

A collaborative network of more than 75 Clean Cities coalitions boosts the country's economic vitality, energy security, and quality of life by advancing the deployment of affordable, efficient, and clean transportation fuels and technologies. Coalitions provide the technical expertise local decision makers and fleets need to understand and implement alternative and renewable fuels, electric vehicles, idle-reduction measures, fuel economy improvements, new mobility choices, and emerging transportation technologies.

ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2023

Clean Cities Coalitions: Advancing Affordable, Efficient, and Clean Transportation Fuels and Technologies

ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2016

Sustainable Remediation of Radionuclides By a Common Sense Approach to Enhanced Attenuation - 16441

Development of in situ and relatively passive remedies for treatment of groundwater contaminated by metals and radionuclides is becoming more important because of the difficulty and cost - both to the environment and financially -- of removing these types of contaminants from the subsurface by pump-and-treat or excavation. In situ technologies rely on reactions that tend to remove contaminants from groundwater by partitioning them to solid phases in the aquifer. Monitored natural attenuation (MNA) relies solely on natural reactions to achieve remedial goals. Enhanced attenuation (EA) uses engineered approaches to supplement remediation when MNA is not sufficient to meet remedial goals. Both approaches leave contaminants in the subsurface and require a high burden of proof that contaminants will not be mobilized and become a risk in the future. Proof of the sustained effectiveness of an EA remedy is made much easier by strategic design. In multi-contaminant plumes, it is important to prioritize contaminants according to the risk they pose, with the recognition that one remedy rarely treats all contaminants. The goal for the engineered portion of the remedy should be maximum risk reduction with minimal engineering. Natural attenuation or negotiated alternate concentration levels will often allow low risk contaminants to go untreated. Whenever possible, the remedy should be consistent with the geochemical evolution of the waste site, insuring that the treated immobilized contaminants are likely to remain relatively immobile for long time frames. Finally, use what nature provides geologically, hydrologically, geochemically, or microbiologically in the remedy design. One of the impediments faced by waste site managers in implementing EA remedies is paralysis by perceived complexity. There are things that must be known to design an effective EA remedy, but there is always the temptation to know everything to eliminate the possibility of failure. Furthermore, there are plenty of people warning of failure if all is not known and they are usually willing to help the design team know all, for a price. Yet, the price of trying to eliminate all risk is never implementing an innovative remedy. All parties involved -- scientists/engineers, waste site managers, regulators and stakeholders must assume some degree of risk to deploy an EA remedy. If all parties are to assume some risk, then trust built through close communication from the start is required. The U.S. Department of Energy Office of Environmental Management has funded an applied field research initiative for several years focused, in part, on developing EA remedies for metals and radionuclides using these guiding principles. This approach to EA remedies grew out of developing and deploying a remediation strategy to replace a pump-and-treat system at the F-Area Seepage Basins on the Savannah River Site. The pump-and-treat system was energy intensive, produced several thousand cubic feet of solid radioactive waste per year, and cost $ 1 million per month to operate. The EA remedy that replaced the pump-and-treat is energy efficient, produces no waste, and costs approximately $1 million per year to maintain. At the F-Area Seepage Basins approximately 7 billion liters of low level radioactive waste solutions were disposed in three unlined basins resulting in contaminated groundwater containing various radionuclides and other contaminants. The primary contaminants of concern are tritium, strontium-90, uranium, and iodine-129. Other key features of the contaminant plume are its acidic nature with pH values as low as 3.2, its vertical stratification in the water table aquifer, and the tendency of the most contaminated portions to follow troughs in the top of the clay separating the upper aquifer zone from the lower aquifer zone. The geology was exploited by installing a funnel-and-gate system into the clay with the barrier portion blocking contaminant flow paths in the troughs in the clay. This forces the most contaminated water to flow through the gates where it encounters an in situ treatment zone created by periodic injections of alkaline solution. The flux of tritium has been reduced significantly by the barrier walls. Strontium-90 and uranium are treated by enhanced sorption in the circum-neutral pH treatment zone, consistent with natural geochemical evolution of the waste site from acidic to more neutral pH. An additional in situ treatment zone was created up-gradient of the one of the gates to treat iodine-129. Sub-micrometer diameter silver chloride particles were injected into the aquifer by direct push methods to create the treatment zone. In the laboratory and in a field pilot test the poorly soluble silver chloride particles reacted with iodide to form much less soluble silver iodide. Evaluation of the effectiveness of the silver chloride is ongoing. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗