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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Influence of Exercise Modality on Cerebral-Ocular Hemodynamics and Pressures

Background: Moderate and high intensity aerobic or resistance exercise has clearly identified benefits for cardiac, muscle, and bone health. However, the impact of such exercise - either as a mitigating or an exacerbating factor - on the development of the visual impairment and intracranial pressure syndrome (VIIP) is unknown. Accordingly, our aim was to characterize the effect of an acute bout of resistance (RE), moderate-intensity continuous (CE), and high-intensity interval exercise (IE) during a cephalad fluid shift on cerebral-ocular hemodynamics and pressures. Methods: 10 male subjects (36 plus or minus 9 years) completed 4 testing days in a 15 degree head-down tilt (HDT): (1) assessment of maximum volume of O (sub 2), (2) RE session (4 sets of 12 repetition maximum leg press exercise), (3) CE session (30 minutes of cycling at 60 percent maximum volume of O (sub 2)), and (4) IE session (4 by 4-minute intervals of exercise at 85 percent maximum volume of O (sub 2) with 3-minute active rest periods). During each session, blood flow (Vivid-e, GE Healthcare) in extracranial arteries (common carotid artery, CCA; internal carotid artery, ICA; external carotid artery, ECA and vertebral artery, VA), and mean blood flow velocity in middle cerebral artery (MCA), internal jugular pressure (IJP; VeinPress), and intraocular pressure (IOP; Icare PRO) were measured at rest, at the end of each resistance or interval set, and every 5 minutes during continuous exercise. Translaminar pressure gradient (TLPG) was estimated by subtracting IJP from IOP. Results: There were no differences across days in pre-exercise resting blood flows or pressures. IOP decreased slightly from HDT rest (20.2 plus or minus 2.3 millimeters of mercury) to exercise (RE: 19.2 plus or minus 2.8 millimeters of mercury; CE: 18.9 plus or minus 3.2 millimeters of mercury; IE: 20.1 plus or minus 2.8 millimeters of mercury), while IJP decreased during CE (31.6 plus or minus 9.5 millimeters of mercury) and RE (32.0 plus or minus 8.1 millimeters of mercury), and increased during IE (35.1 plus or minus 9.5 millimeters of mercury) from HDT rest (33.3 plus or minus 6.5 millimeters of mercury). Estimated TLPG was increased during IE only. Compared to RE and CE, IE resulted in the greatest increase in MCA blood flow velocity and extracranial artery blood flow. Conclusions: These preliminary results suggest that high-intensity IE acutely increases cerebral blood flow, IJP, and TLPG. Alterations in TLPG is one mechanism that may contribute to optic nerve sheath edema in astronauts. Accordingly, acutely raising IOP and/or orbital pressure during exercise could optimize cerebral-ocular pressures during spaceflight.

Scott, J.↗
NASA NTRS2022

The Coronal Veil

Coronal loops, seen in solar coronal images, are believed to represent emission from magneticflux tubes withcompact cross sections. We examine the 3D structure of plasma above an active region in a radiativemagnetohydrodynamic simulation to locate volume counterparts for coronal loops. In many cases, a loop cannot belinked to an individual thin strand in the volume. While many thin loops are present in the synthetic images, thebright structures in the volume are fewer and of complex shape. We demonstrate that this complexity can formimpressions of thin bright loops, even in the absence of thin bright plasma strands. We demonstrate the difficulty ofdiscerning from observations whether a particular loop corresponds to a strand in the volume, or a projectionartifact. We demonstrate how apparently isolated loops could deceive observers, even when observations frommultiple viewing angles are available. While we base our analysis on a simulation, the mainfindings areindependent from a particular simulation setup and illustrate the intrinsic complexity involved in interpretingobservations resulting from line-of-sight integration in an optically thin plasma. We propose alternativeinterpretation for strands seen in Extreme Ultraviolet images of the corona. The“coronal veil”hypothesis ismathematically more generic, and naturally explains properties of loops that are difficult to address otherwise—such as their constant cross section and anomalously high density scale height. We challenge the paradigm ofcoronal loops as thin magneticflux tubes, offering new understanding of solar corona, and by extension, of othermagnetically confined bright hot plasmas

A Malanushenko↗
DOE OSTI2013

Management Challenges in Developing Performance Assessments and Effectively Communicating Their Results - 13612

The end of the Cold War has left a legacy of approximately 37 million gallons of radioactive waste in the aging waste tanks at the Department of Energy's Savannah River Site (SRS). A robust program is in place to remove waste from these tanks, treat the waste to separate into a relatively small volume of high level waste and a large volume of low-level waste, and to actively dispose of the low-level waste on-site and close the cleaned waste tanks and associated ancillary structures. To support performance-based, risk-informed decision making, performance assessments have been developed for the low-level waste disposal facility and for the SRS Tank Farms. Although these performance assessments share many similar features, the nature of the hazards and associated containments differ. As a management team, we are challenged to effectively communicate both the similarities and differences of these performance assessments, how they should be used to support sound decision making for treatment, disposal and waste tank cleaning decisions, and in defending their respective assumptions to the regulatory community and the public but, equally important, to our own corporate decision makers and operations personnel. Effective development and defense of these performance assessments, and effective interpretation and communication of the results are key to making cost-effective, pragmatic decisions for the safe disposal of the low-level waste and stabilization and operational closure of the cleaned tanks and associated structures. This paper will focus on the importance and challenges in communicating key attributes, conclusions and operational implications within a company. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Regulatory Framework for Salt Waste Disposal and Tank Closure at the Savannah River Site - 13663

The end of the Cold War has left a legacy of approximately 37 million gallons of radioactive waste in the aging waste tanks at the Department of Energy's Savannah River Site (SRS). A robust program is in place to remove waste from these tanks, treat the waste to separate into a relatively small volume of high-level waste and a large volume of low-level waste, and to actively dispose of the low-level waste on-site and close the waste tanks and associated ancillary structures. To support performance-based, risk-informed decision making and to ensure compliance with all regulatory requirements, the U.S. Department of Energy (DOE) and its current and past contractors have worked closely with the South Carolina Department of Health and Environmental Control (SCDHEC), the U.S. Environmental Protection Agency (EPA) and the Nuclear Regulatory Commission (NRC) to develop and implement a framework for on-site low-level waste disposal and closure of the SRS waste tanks. The Atomic Energy Act of 1954, as amended, provides DOE the authority to manage defense-related radioactive waste. DOE Order 435.1 and its associated manual and guidance documents detail this radioactive waste management process. The DOE also has a requirement to consult with the NRC in determining that waste that formerly was classified as high-level waste can be safely managed as either low-level waste or transuranic waste. Once DOE makes a determination, NRC then has a responsibility to monitor DOE's actions in coordination with SCDHEC to ensure compliance with the Title 10 Code of Federal Regulations Part 61 (10CFR61), Subpart C performance objectives. The management of hazardous waste substances or components at SRS is regulated by SCDHEC and the EPA. The foundation for the interactions between DOE, SCDHEC and EPA is the SRS Federal Facility Agreement (FFA). Managing this array of requirements and successfully interacting with regulators, consultants and stakeholders is a challenging task but ensures thorough and thoughtful processes for disposing of the SRS low-level waste and the closure of the tank farm facilities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Integration of performance assessments and 3116 basis documents within the Savannah River Site liquid waste facilities - 15375

The end of the Cold War has left a legacy of over 136 million liters (36 million gallons) of radioactive waste in the aging waste tanks at the Department of Energy's Savannah River Site (SRS). A robust program is in place to remove waste from these tanks, treat the waste to separate it into a relatively small volume of high-level waste and a large volume of low-level waste, and to actively dispose of the low-level waste on-site. This process allows the US Department of Energy (DOE) to move forward with closure of the cleaned waste tanks and associated ancillary structures. To support performance-based, risk decision making for closure and disposal activities, three individual performance assessments (PAs) have been developed - salt-stone Disposal Facility, F-Tank Farm and H-Tank Farm. In addition, three Waste Determinations (WDs) have been made by the Secretary of Energy, in consultation with the Nuclear Regulatory Commission (NRC), under the authority of Section 3116 of the Ronald W. Reagan National Defense Authorization Act for Fiscal Year 2005 (NDAA Section 3116). To support these waste determination decisions, individual '3116 Basis Documents' were developed that describe the assumptions and conditions under which the criteria outlined in NDAA Section 3116 are met. The development of each of the PAs represented a long and arduous effort that involved the development of both deterministic and probabilistic conceptual models of the facilities, the development of assumptions and associated ranges, uncertainty and sensitivity analyses, model data collection and analyses, writing of the actual performance assessment, internal and external peer reviews, and ultimately approval by DOE. Similarly, the development of the 3116 Basis Documents represents similar time and financial commitments. At the end of these efforts, after years of preparation and millions of dollars in investment, we have thousands of pages of highly technical text, tables of data and hundreds of graphs and charts all contained in a series of thick binders that fit neatly on the shelf of a bookcase. We were done - right? Actually, we were just getting started. Performance Assessments and 3116 Basis Documents are living documents that shape day-to-day and long-term decision making in the operation of a low-level waste disposal facility (e.g., salt-stone Disposal Facility) or in area closure activities (e.g., F-Tank Farm or H-Tank Farm). Although these documents do not contain specifically described requirements per se, they do utilize specific assumptions that, if changed significantly, could result in no longer being able to demonstrate that there is reasonable assurance that the required performance objectives or the criteria from NDAA Section 3116 can be met. Savannah River Remediation LLC (SRR), the contractor responsible for Liquid Waste operations at SRS, has not only developed the PAs and 3116 Basis Documents to support this work and shepherded these documents through the DOE approval process, but has also developed the processes and procedures to ensure the successful implementation and integration of these documents into day-to-day decision making within the associated facilities. This paper describes these processes, including the Un-reviewed Waste Management Question process and the PA Maintenance process, and provides specific examples of their successful implementation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

127 Xe quantification method development and intercomparison exercise

Monitoring of the atmosphere for fission products ( 131m Xe, 133m Xe, 133 Xe, and 135 Xe) is performed by various laboratories to detect nuclear explosions. Quantification of 127 Xe is not routinely performed by laboratories measuring atmospheric radioxenon because it is not a fission product. 127 Xe was recently detected by a ground-based beta-gamma air monitoring system. When measured using beta-gamma coincidence detector systems, such as those in use on the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), 127 Xe can interfere with the quantification of fission product radioxenon due to overlap of the 127 Xe beta-gamma coincidence signatures with those of fission product radioxenon. Here, this work demonstrates quantification of 127 Xe at different laboratories with different measurement techniques. Production and purification of 127 Xe was performed by neutron activation of enriched 126 Xe. The purified 127 Xe was then split between laboratories, and detection and quantification methods were developed. At Idaho National Laboratory, a quantification method involving high purity germanium detectors was devised that included self-attenuation correction. At AWE, a beta-gamma coincidence counting method, as used in support of the IMS, was modified to enable the measurement and analysis of the 127 Xe samples. Corrections were made for self-attenuation, which showed a strong xenon volume dependency, for some coincidence signatures. The gas sample activity concentration was used as the comparison metric and it showed excellent agreement between the methods.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
NASA NTRS1987

Physiologic adaptation of man in space; Proceedings of the Seventh International Man in Space Symposium, Houston, TX, Feb. 10-13, 1986

Topics discussed in this volume include space motion sickness, cardiovascular adaptation, fluid shifts, extravehicular activity, general physiology, perception, vestibular response modifications, vestibular physiology, and pharmacology. Papers are presented on the clinical characterization and etiology of space motion sickness, ultrasound techniques in space medicine, fluid shifts in weightlessness, Space Shuttle inflight and postflight fluid shifts measured by leg volume changes, and the probability of oxygen toxicity in an 8-psi space suit. Consideration is also given to the metabolic and hormonal status of crewmembers in short-term space flights, adaptive changes in perception of body orientation and mental image rotation in microgravity, the effects of a visual-vestibular stimulus on the vestibulo-ocular reflex, rotation tests in the weightless phase of parabolic flight, and the mechanisms of antimotion sickness drugs.

Holland, Albert W.↗
NASA NTRS1978

Environmental exposure effects on composite materials for commercial aircraft

Activities reported include completion of the program design tasks, resolution of a high fiber volume problem and resumption of specimen fabrication, fixture fabrication, and progress on the analysis methodology and definition of the typical aircraft environment. Program design activities including test specimens, specimen holding fixtures, flap-track fairing tailcones, and ground exposure racks were completed. The problem experienced in obtaining acceptable fiber volume fraction results on two of the selected graphite epoxy material systems was resolved with an alteration to the bagging procedure called out in BAC 5562. The revised bagging procedure, involving lower numbers of bleeder plies, produces acceptable results. All required laminates for the contract have now been laid up and cured. Progress in the area of analysis methodology has been centered about definition of the environment that a commercial transport aircraft undergoes. The selected methodology is analagous to fatigue life assessment.

Hoffman, D. J.↗
DOE OSTI2020

Rate Enhancement of Acid-Catalyzed Alcohol Dehydration by Supramolecular Organic Capsules

The presence of a (sub)nanometric environment has been demonstrated to enhance the rate of homogeneous acid-catalyzed reactions. Conventionally, such catalysts are constructed by directly embedding a catalytically active acid site into the structure of a porous material, linking the acid properties with the properties of the embedding solid. Here, a holoenzyme mimicking approach was used, in which a self-assembled hexameric resorcinarene capsule (1.4 nm 3 cavity) acts like an apoenzyme that transforms into a catalytically active site by hosting hydrated HCl as a cofactor. This capsule binds the hydronium ion together with cyclohexanol (CyOH) and catalyzes the dehydration to cyclohexene with enhanced rates that are 2 orders of magnitude higher than those in the unconstrained environment. Kinetic analysis shows that cyclohexanol dehydration proceeds via an E2 mechanism on hydrated HCl in the unconstrained environment, while the constrained environment of the active capsule induces the stabilization of an ionic intermediate, allowing an E1 mechanism to dominate. By comparison with the reaction in zeolite environments, we show that the direct chemical environment of the capsule or a zeolite wall exerts only a minor direct influence. The volume constraint increases the reaction rate by inducing a larger activation entropy, indicating the stabilization of a later transition state in the E1 mechanism, as well as a higher reaction space of the carbenium ion constituting the transition state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Predictive Direct DC-Link Control for 7.2 kV Three-Port Low-Inertia Solid-State Transformer With Active Power Decoupling

Promising for applications including renewable energy and electric vehicle fast charging, a medium-voltage (MV) solid-state transformer (SST) typically has multiple modules series stacked, which requires the modules to be single phase. One critical issue of the single-phase SST is the double-line-frequency power ripple. Traditionally, large passives are used to buffer the ripple, resulting in significantly increased volume and cost. This article for the first time proposes active power decoupling (APD) for the SST and a predictive direct DC-link control method, using a current-source single-stage SST as an example. An electrolytic capacitor-less buffer port is used to absorb the ripple, which tolerates up to a 30% voltage ripple for small capacitance. The APD SST control is challenging. First, the current-source SST realizes isolation, DC link, and multiport in a single stage. Second, different from conventional SSTs or APD converters, the low-inertia DC link in this SST has a 40% switching ripple, which is difficult to stabilize. To address the control challenge, a direct DC-link control architecture and a predictive control method are proposed. Simulation and experimental results verify the proposed control method on an MV SiC modular soft-switching solid-state transformer (M-S4T) prototype. Here, the proposed APD reduces the SST volume by 53.8%. Importantly, the proposed concept is not limited to the M-S4T but is generic to other SSTs or APD converters.

14 SOLAR ENERGY↗
NASA NTRS1992

Lunar base activities and the lunar environment

The Moon is an attractive site for astronomical observatories and other facilities because of the absence of a substantial lunar atmosphere and the stability of the lunar surface. The present lunar atmosphere is sufficiently transparent that there is no significant image distortion due to absorption or refraction. This thin atmosphere results from a combination of small sources and prompt losses. The major source that has been identified is the solar wind, whose total mass input into the lunar atmosphere is approximately 50 gm/sec. The major components of the solar wind are light elements (H and He) that promptly escape from the lunar surface by exospheric evaporation (Jeans' escape). The principal atmospheric loss mechanism for heavier gases is photoionization within a period of weeks to months, followed by immediate loss to the solar wind. Lunar base activities will modify the lunar atmosphere if gas is released at a larger rate than that now occurring naturally. Possible gas sources are rocket exhaust, processing of lunar materials, venting of pressurized volumes, and astronaut life support systems. For even modest lunar base activity, such sources will substantially exceed natural sources, although effects are expected to be localized and transient. The Apollo database serves as a useful reference for both measurements of the natural lunar environment and its modification by lunar base activities.

Vondrak, Richard R.↗
NASA NTRSDate not supplied

NASA’s Commercial Smallsat Data Acquisition (CSDA) Program Data System

The National Aeronautic and Space Administration (NASA) Commercial Smallsat Data Acquisition (CSDA) Program was established to identify, evaluate, and acquire data from commercial satellite companies that support and complement NASA’s Earth sciences missions and research goals. Since becoming a sustained program in 2020, CSDA has been developing a data system to provide scalable, efficient, continuous, and repeatable data management processes for all commercial data acquired by NASA. This includes providing access to commercial data to approved science investigators through NASA developed and vendor operated interfaces. As the commercial data user community and volume of data acquired by CSDA has grown, the team managing these data has adapted technologies and services to better address the data and information search, discovery, and access needs of the science user community. This presentation will provide an overview of CSDA Program data system activities including data availability, development of CSDA user interfaces, challenges in managing large-volume diverse datasets, and long-term data preservation activities to retain data for scientific reproducibility.

data management↗
NASA NTRS1990

Observations of the plasma environment during an active ionospheric ion beam injection experiment

Several sounding rocket flights have been used to clarify the electrodynamics of neutral beam releases of Ar ions in the upper ionosphere, by varying the Ar's point of release with respect to the diagnostic payload. A volume of 10-m radius centered on the Ar release payload is measured for broadband wave activity; the superthermal neutralizing beam electrons become magnetized in this volume for across-field plasma releases, and ambient electrons are accelerated to energies of several hundred eV. This is speculated to be due to wave turbulence rather than payload-neutralization.

Arnoldy, R. L.↗
DOE OSTI2019

Biotransformation of Isoeugenol into Vanillin Using Immobilized Recombinant Cells Containing Isoeugenol Monooxygenase Active Aggregates

For efficiently enhancing the activity of isoeugenol monooxygenase, a whole cell overproducing active aggregate IEM720-18A was successfully fabricated via the fusion of amphiphilic short peptide 18A (EWLKAFYEKVLEKLKELF) and isoeugenol monooxygenase and then efficiently expressed in E. coli BL21 (DE3). Such resulting bacteria, E. coli BL21 (DE3) harboring pET30a-IEM720-18A was applied in the biotransformation of isoeugenol to vanillin with the optimization of cultivation conditions. Our results revealed that the vanillin concentration reached to the highest level (14.5 mmol/L) under the optimized reaction conditions including 1.5-g cells containing active aggregate of IEM720-18A, 10% (v/v) dimethyl sulfoxide (DMSO), 100 mmol/L isoeugenol, 50 mmol/L glycine-sodium hydroxide buffer (pH 10.5) in 10 mL reaction volume, and 200 rpm at 25 °C for 36 h. Moreover, the active aggregate IEM720-18A was immobilized with 100 mmol/L glutaraldehyde at 4 °C to improve the operational stability. The highest activity could be achieved when the reactions were carried out at 25 °C and the relative activity of the immobilized enzyme maintained over 60% after seven recycles. Our study provides a new approach to the biotransformation of isoeugenol into vanillin.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1978

Space industrialization. Volume 3: World and domestic implications

The status of worldwide space industralization activities is assessed as well as the benefits to be anticipated from enhanced activities. Methods for stimulating space industralization growth are discussed with emphasis on foreign and international activities, national and world impact assessments, industry/government interfaces, legal implications, institutional implications, economics and capitalization, and implementation issues and recommendations.

Source record↗
NASA NTRS1981

NASA's Role in Aeronautics: A Workshop. Volume 3: Transport aircraft

Segments of the spectrum of research and development activities that clearly must be within the purview of NASA in order for U.S. transport aircraft manufacturing and operating industries to succeed and to continue to make important contributions to the nation's wellbeing were examined. National facilities and expertise; basic research, and the evolution of generic and vehicle class technologies were determined to be the areas in which NASA has an essential role in transport aircraft aeronautics.

Source record↗