Search NASA⌕ Search

SEARCH · Search NASA

Results for “Transportation consideration”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6

The solar UV environment and bacterial spore UV resistance: considerations for Earth-to-Mars transport by natural processes and human spaceflight

The environment in space and on planets such as Mars can be lethal to microorganisms because of the high vacuum and high solar radiation flux, in particular UV radiation, in such environments. Spores of various Bacillus species are among the organisms most resistant to the lethal effects of high vacuum and UV radiation, and as a consequence are of major concern for planetary contamination via unmanned spacecraft or even natural processes. This review focuses on the spores of various Bacillus species: (i) their mechanisms of UV resistance; (ii) their survival in unmanned spacecraft, space flight and simulated space flight and Martian conditions; (iii) the UV flux in space and on Mars; (iv) factors affecting spore survival in such high UV flux environments.

Review↗

Geospatial analysis of freight accessibility and job attraction: The role of interstate ramps, airports, ports, and rail

The number of jobs within an industry is significantly influenced by geographical location, with transportation infrastructure playing a key role. While previous research has largely focused on how access to jobs affects employment, less attention has been given to how transportation infrastructure impacts business operations and job attraction. Here, this study addresses this gap by examining how the ease of transporting products to key transportation facilities affects job numbers in freight-intensive industries. Using job data from the Longitudinal Employment Household Dynamics dataset at the Census Tract level, we applied a non-parametric model to assess the impact of proximity to interstate ramps, rail intermodals, ports, and airports. Our analysis revealed that closer transportation infrastructure generally has a greater impact on employment. Specifically, interstate ramps are crucial for attracting jobs, particularly in rural areas, while airport proximity is essential for industries dealing with high-value, time-sensitive goods, as seen notably in Massachusetts. The importance of transportation facilities varies considerably across states and industries. The findings and method in this study can be used by transportation agencies for freight planning.

99 GENERAL AND MISCELLANEOUS↗

Theoretical monochromatic-wave-induced currents in intermediate water with viscosity and nonzero mass transport

Wave-induced mass-transport current theories with both zero and nonzero net mass (or volume) transport of the water column are reviewed. A relationship based on the Longuet-Higgens theory is derived for wave-induced, nonzero mass-transport currents in intermediate water depths for a viscous fluid. The relationship is in a form useful for experimental applications; therefore, some design criteria for experimental wave-tank tests are also presented. Sample parametric cases for typical wave-tank conditions and a typical ocean swell were assessed by using the relation in conjunction with an equation developed by Unluata and Mei for the maximum wave-induced volume transport. Calculations indicate that substantial changes in the wave-induced mass-transport current profiles may exist dependent upon the assumed net volume transport. A maximum volume transport, corresponding to an infinite channel or idealized ocean condition, produces the largest wave-induced mass-transport currents. These calculations suggest that wave-induced mass-transport currents may have considerable effects on pollution and suspended-sediments transport as well as buoy drift, the surface and midlayer water-column currents caused by waves increasing with increasing net volume transports. Some of these effects are discussed.

Talay, T. A.↗

Evidence for Arctic Ozone Depletion in Late February and early March 1994

Significant chemical ozone (O3 ) loss in the 1993-94 Arctic winter occurred mainly during an unusually late cold spell of approximately 10 days in late Feb/early Mar. Over the 30 d period studied (including the cold spell), observed vortex-averaged O3 at 465 K (approximately 40 hPa) decreased by approximately 10%. New three-dimensional, diabatic trajectory calculations show that this observed decrease represents only about half of the net chemical loss (approximately 20%) during the 30 day period. The resupply of lower stratospheric O3 by transport in Feb 1994 was considerably greater than in 1993, when transport masked only about a quarter of the chemical loss in Feb/Mar. The net estimated chemical loss over 30 days in 1994 was comparable to that over the same 30 days in 1993, but mainly occurred at a faster rate during the brief cold spell. These results highlight the impact of Arctic interannual variability on the relative roles of chemistry and dynamics in O3 evolution during recent Arctic winters.

Manney, G. L.↗

Vehicle design considerations for active control application to subsonic transport aircraft

The state of the art in active control technology is summarized. How current design criteria and airworthiness regulations might restrict application of this emerging technology to subsonic CTOL transports of the 1980's are discussed. Facets of active control technology considered are: (1) augmentation of relaxed inherent stability; (2) center-of-gravity control; (3) ride quality control; (4) load control; (5) flutter control; (6) envelope limiting, and (7) pilot interface with the control system. A summary and appraisal of the current state of the art, design criteria, and recommended practices, as well as a projection of the risk in applying each of these facets of active control technology is given. A summary of pertinent literature and technical expansions is included.

Hofmann, L. G.↗

Considerations in the Integration of Small Aircraft Transportation System Higher Volume Operations (SATSHVO) in the National Airspace System (NAS)

The Small Aircraft Transportation System Higher Volume Operations (SATS HVO) concept holds the promise for increased efficiency and throughput at many of the nations under-used airports. This concept allows for concurrent operations at uncontrolled airports that under today s procedures are restricted to one arrival or one departure operation at a time, when current-day IFR separation standards are applied. To allow for concurrent operations, SATS HVO proposes several fundamental changes to today's system. These changes include: creation of dedicated airspace, development of new procedures and communications (phraseologies), and assignment of roles and responsibilities for pilots and controllers, among others. These changes would affect operations on the airborne side (pilot) as well as the groundside (controller and air traffic flow process). The focus of this paper is to discuss some of the issues and potential problems that have been considered in the development of the SATS HVO concept, in particular from the ground side perspective. Reasonable solutions to the issues raised here have been proposed by the SATS HVO team, and are discussed in this paper.

Lohr, Gary W.↗

Use of Multi-Attribute Utility Analyses to Assess Transportation Routes from ISFSIs - 20535

With two consolidated interim storage facilities for used nuclear fuel (UNF) having applied for storage licenses, there is the potential need to transport UNF in the U.S. from shutdown reactor sites to complete the site cleanup and from operating reactor sites who may be running out of storage options (e.g., spent fuel pools are nearly full and dry storage facilities are reaching licensed capacity). At some of the shutdown reactor sites, only the independent spent fuel storage installation (ISFSI) exists and often there remains a degraded transportation infrastructure for performing shipments from these sites. At other sites (e.g., operating reactor plants), the existing transportation infrastructure on the site is unchanged and sufficient for moving UNF, but the environment around the route may have changed (e.g., what was once a rural setting has transformed into a more urban setting) and/or local stakeholders want their input taken into consideration in UNF transportation activities. So, although preliminary evaluations have been performed to identify viable modes of transport from these sites using rail, barge, and/or heavy haul truck, if multiple options exist for moving the UNF from the site (e.g., multiple truck routes or a truck and a barge route both exist) then an evaluation that takes input from multiple stakeholders should be considered to identified the preference (e.g., ranking) of routes from a site. Orano has supported the development of several studies examining the viable routes for removing UNF from some of these sites and has utilized a multi-attribute utility analysis (MUA) to establish a ranking of routes and associated modes to move the UNF from the ISFSIs to a Class I rail carrier. The ultimate result from the MUA is a list(s) of the most to the least favored/preferred routes from the site. This paper provides an overview of the MUA methodology and provides an example of its application to a site with a shutdown reactor. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Radionuclide Screening Analysis and Transport Parameters for Pahute Mesa Detonations, Nevada National Security Site

A “screening analysis” is implemented at Pahute Mesa (PM), Nevada National Security Site (NNSS), to determine subsets of the 43 radionuclides listed in the radionuclide inventory of Finnegan et al. (2016) that are of relevance or potential relevance to the hydrologic source term (HST) for assessment of radionuclide transport in groundwater. Consideration is added to how levels of contamination are defined and whether any other radionuclides not in the inventory are relevant to the HST. A model is developed to estimate a range of possible source concentrations in groundwater that account for uncertainty in partitioning into melt glass and sorption into surrounding rock of the exchange zone for the 82 PM underground nuclear tests detonated in vertical shafts. The model also accounts for the varied hydrogeochemical settings. Transport parameters needed for the screening model calculations are developed from databases for hydrogeologic units, chemistry, mineralogy, fracture spacing, fracture aperture, fracture openness, matrix porosity, bulk density, saturation, and alteration. Of key importance is consideration of diagenetic zonation of the mineralogy related to hydrothermal alteration. The screening analysis compares model results with available groundwater radiochemistry data. Consistency between screening model results and available data helps validate the model for application to all 43 radionuclides, most of which have no measurements or only non-detect measurements of concentration in groundwater. The screening analysis determines that ten radionuclides – tritium, Sr-90, I-129, Cs-137, U-232, U-233, U-234, U-238, and the total of Pu-239 and Pu-240 are relevant to the HST. Determination of relevance is primarily based on data and/or model results indicating source concentration exceeding a maximum contaminant level (MCL) out to 100 years since the time of detonation. U-238 is relevant to assessment of contamination relative to MCLs for uranium and gross alpha particle activity. Five other radionuclides – C-14, Cl-36, Tc-99, Np-237, and Pu-238 – are determined potentially relevant to the HST based on a 0.1 MCL threshold. The screening analysis recommends additional attention to the natural daughter radionuclides of the uranium series (U-238) and thorium series (Th-232) decay chains, particularly Ra-226 and Ra-228, that were not included the inventory.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Techno-Economic Evaluation of Strategies to Approach Net-Zero Carbon Sustainable Aviation Fuel via Woody Biomass Gasification and Fischer-Tropsch Synthesis

Reducing the carbon dioxide (CO2) emissions from the transportation industry is a key target for achieving global net-zero carbon goals. Wide-spread electrification, efficient engine design, and alternative fuel implementations have been introduced for light-duty vehicles and are projected to significantly reduce light-duty emissions in the near future. Conversely, the aviation sector contributes considerably towards transportation-based carbon emissions, but current projections do not show substantial reductions in carbon emissions over time. Challenges for the aviation sector include low compatibility with electrification, relative inflexibility to variations in fuel properties, and requirement of high energy density fuels. Thus, identifying pathways to decarbonize the aviation sector via liquid low- or net-zero carbon biofuels that are compatible with current aviation infrastructure is crucial. This work investigates the economic feasibility of approaching net-zero carbon sustainable aviation fuel (SAF) from woody biomass via gasification and Fischer-Tropsch synthesis. In doing so, this assessment identifies the economic opportunities and trade-offs of several carbon mitigation strategies coupled with renewable resource interventions required to approach net-zero carbon fuels via biomass. Renewable natural gas and green hydrogen utilization strategies are assessed to examine the impact of fuel yield improvements versus renewable resource cost. Additionally, both carbon capture and sequestration (CCS) and carbon capture and utilization (CCU) are considered in this analysis to help mitigate carbon loss to the atmosphere. Each scenario was assessed on cost, carbon efficiency, energy efficiency, and overall technology-readiness level (TRL). The results of this analysis show that renewable natural gas, green hydrogen, and CCS can be viewed as a low-cost, near-term carbon abatement strategies. However, in the long-term, deployment of more expensive and less technologically mature CCU technologies can make use of point sources of CO2 to boost overall fuel production.

aviation fuel↗

Life Science on the International Space Station Using the Next Generation of Cargo Vehicles

With the retirement of the Space Shuttle and the transition of the International Space Station (ISS) from assembly to full laboratory capabilities, the opportunity to perform life science research in space has increased dramatically, while the operational considerations associated with transportation of the experiments has changed dramatically. US researchers have allocations on the European Automated Transfer Vehicle (ATV) and Japanese H-II Transfer Vehicle (HTV). In addition, the International Space Station (ISS) Cargo Resupply Services (CRS) contract will provide consumables and payloads to and from the ISS via the unmanned SpaceX (offers launch and return capabilities) and Orbital (offers only launch capabilities) resupply vehicles. Early requirements drove the capabilities of the vehicle providers; however, many other engineering considerations affect the actual design and operations plans. To better enable the use of the International Space Station as a National Laboratory, ground and on-orbit facility development can augment the vehicle capabilities to better support needs for cell biology, animal research, and conditioned sample return. NASA Life scientists with experience launching research on the space shuttle can find the trades between the capabilities of the many different vehicles to be confusing. In this presentation we will summarize vehicle and associated ground processing capabilities as well as key concepts of operations for different types of life sciences research being launched in the cargo vehicles. We will provide the latest status of vehicle capabilities and support hardware and facilities development being made to enable the broadest implementation of life sciences research on the ISS.

Robinson, J. A.↗

Conjugated Polymer Controlled Morphology and Charge Transport of Small-Molecule Organic Semiconductors

In this study, we report an efective approach to tune the crystallization, microstructure and charge transport of solution-processed organic semiconductors by blending with a conjugated polymer additive poly(3-hexylthiophene) (P3HT). When 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) was used as a model semiconductor material to mix with diferent amount of P3HT, their intermolecular interactions led to distinctive TIPS pentacene flm morphologies, including randomly-oriented crystal ribbons, elongated needles with enhanced long-range order, and grasslike curved microwires with interlinkages. Each type of morphology was found to further correlate to considerably diferent charge transport and device performance. As compared to pristine TIPS pentacene devices, bottom-gate, top-contact OTFTs with 2% in weight P3HT additive showed a 2-fold and 5-fold improvement of average feld-efect mobility and performance consistency (defned as the ratio of average mobility to the standard deviation), respectively. The improvement in transistor electrical performance can be attributed to the combined efect of enhanced crystal orientation and uniformity, as well as increased areal coverage. This work can be applied beyond the particular example demonstrated in this study and to tune the charge transport of other small-molecule organic semiconductors in general.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Pebble Tanker Model for Nuclear Criticality Safety Needs

This report documents a study performed to investigate the requirements for criticality safety benchmark experiments for high-assay, low-enriched uranium (HALEU) fuel in transportation applications. In this work, an exploratory application model, the “Pebble Tanker,” was developed to represent TRISO fuel in a transportation scenario for an analysis of the validation basis in industrial quantities. An aspect of the criticality validation process involves assessing the “similarity” between application and experimental benchmark systems through an integral index parameter evaluation. Here, this includes propagating nuclear data uncertainties and calculating a correlation coefficient (hereinafter referred to as “c k ”) to evaluate the similarity of benchmark experiments compared with the application Pebble Tanker model. Finding sufficient critical benchmark experiments allows for the evaluation of bias and bias uncertainty, thus determining the upper subcritical limit (USL) of the transportation package. A target k eff of ~0.94 was used in this work to establish appropriate modeling conditions, reflecting a reasonable estimate for a USL. Two container models were investigated: one with the Hermes-type pebble and one with the Pebble Bed Modular Reactor (PBMR)–type pebble. The models were simplified, considering only fuel, containment structure, and either water or air. This allows a focus on the underlying physics of applications involving TRISO fuel pebbles using the Pebble Tanker model. A crucial consideration is the transport package's ability to safely hold pebbles while flooded, maintaining subcritical conditions. Tools available in the SCALE 6.3.1 suite—the CSAS6-Shift, TSUNAMI-3D-Shift, and TSUNAMI-IP sequences—were employed for neutronics and sensitivity and uncertainty (S/U) analysis of the Pebble Tanker. Findings demonstrated sufficient available critical experiment benchmarks to perform a validation of the Pebble Tanker in the most reactive state, i.e., when the Tanker is flooded.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Current status of the electron transport line from RCS to ESR: RTE line

The electron injection system of the U.S. Electron-Ion Collider (EIC) is located outside of the RHIC tunnel. Electrons beams accelerated by the Rapid Cycling Synchrotron (RCS) must be transported to the Electron Storage Ring (ESR), which resides within the RHIC tunnel. To accomplish this, a dedicated beam transport line, referred to as RTE (RCS-to-ESR) line is being designed. The proposed conceptual design comprises three main sections; RCS extraction, a vertical bend and dispersion suppression region, and ESR injection matching. The extraction section uses pulsed kickers and septum magnets to achieve a total deflection angle of 3 degrees. To align the injection section with ESR, the beamline must provide a vertical elevation of 1.68 m, and an array of FODO cells is used to suppress the vertical dispersion. The total length of the RTE line is approximately 133 m, and this paper presents the current design status and considerations for this transport line.

Accelerator Physics↗

Community rotorcraft air transportation benefits and opportunities

Information about rotorcraft that will assist community planners in assessing and planning for the use of rotorcraft transportation in their communities is provided. Information useful to helicopter researchers, manufacturers, and operators concerning helicopter opportunities and benefits is also given. Three primary topics are discussed: the current status and future projections of rotorcraft technology, and the comparison of that technology with other transportation vehicles; the community benefits of promising rotorcraft transportation opportunities; and the integration and interfacing considerations between rotorcraft and other transportation vehicles. Helicopter applications in a number of business and public service fields are examined in various geographical settings.

Gilbert, G. A.↗

Carrier Diffusion Lengths Exceeding 1 μm Despite Trap-Limited Transport in Halide Double Perovskites

In this work we image charge carrier transport over nanometers–micrometers and picoseconds–microseconds in halide double perovskites Cs 2 AgBiBr 6 and Cs 2 AgTlBr 6 single crystals using stroboscopic scattering microscopy. Both materials exhibit long, microsecond carrier lifetimes because of their indirect or symmetry-forbidden direct bandgaps. We extract free-charge and trap-limited mobilities near the surface and in the crystal bulk. The free-charge mobilities for both materials (~10–50 cm 2 /(V s)) can reach those reported for archetypal lead halide perovskites. We measure trap densities exceeding 10 17 cm –3 within ~20 nm of the crystal surface. Measurements on freshly cleaved or thermally annealed crystals suggest the traps are primarily halide vacancies that likely form through surface bromine degassing. Although these traps considerably slow charge transport, they are energetically shallow, enabling thermally induced detrapping and mobile carriers over microseconds at room temperature. This defect tolerance yields carrier diffusion lengths exceeding 1 μm even in the presence of large trap densities and under solar excitation conditions where traps are not saturated. These results suggest that halide double perovskites could rival the best lead-based perovskites for photovoltaic and optoelectronic applications.

36 MATERIALS SCIENCE↗

Integrating computation and experiment to investigate photoelectrodes for solar water splitting at the microscopic scale.

CONSPECTUS: Photoelectrochemical water-splitting is a promising and sustainable way to store the energy of the sun in chemical bonds and use it to produce hydrogen gas, a clean fuel. The key components in photoelectrochemical cells (PECs) are photoelectrodes, including a photocathode that reduces water to hydrogen gas and a photoanode that oxidizes water to oxygen gas. Materials used in photoelectrodes for PECs must effectively absorb sunlight, yield photogenerated carriers, and exhibit electronic properties that enable the efficient shuttling of carriers to the surface to participate in relevant water-splitting reactions. Discovering and understanding the key characteristics of optimal photoelectrode materials is paramount to the realization of PEC technologies. Oxide-based photoelectrodes can satisfy many of these materials requirements, including stability in aqueous environments, band edges with reasonable alignment with the redox potentials for water splitting, and ease of synthesis. However, oxide photoelectrodes generally suffer from poor charge transport properties and considerable bulk electron-hole separation, and they have relatively large band gaps. Numerous strategies have been proposed to improve these aspects and understand how these improvements are reflected in the photoelectrochemical performance. Unfortunately, the structural and compositional complexity of multinary oxides accompanied by the inherent complexity of photoelectrochemical processes makes it challenging to understand the individual effects of composition, structure, and defects in the bulk and on the surface on a material's photoelectrochemical properties. The integration of experiment and theory has great potential to increase our atomic-level understanding of structure-composition-property relationships in oxide photoelectrodes. In this Account, we describe how integrating experiment and theory is beneficial for achieving scientific insights at the microscopic scale. We highlight studies focused on understanding the role of (i) bulk composition via solid-state solutions, intercalation, and comparison with isoelectronic compounds, (ii) dopants for both the anion and cation and their interactions with oxygen vacancies, and (iii) surface/interface structure in the photocurrent generation and photoelectrochemical performance in oxide photoelectrodes. In each instance, we outline strategies and considerations for integrating experiment and theory and describe how this integration led to valuable insights and new directions in uncovering structure-composition-property relationships. Our aim is to demonstrate the unique value of combining experiment and theory in studying photoelectrodes and to encourage the continued effort to bring experiment and theory in closer step with each other.

Wang, Wennie↗

A Technical basis for in-house calibration of 252 Cf neutron source emission rates

10CFR835 stipulates that radiation protection instruments must be calibrated at least annually. Accordingly, calibration of dose rate instruments are reliant on well-known reference fields. The neutron-free-in-air facility (NFIA) located at TA36-0214 provides such a capability for neutron remmeters. One of the reference NFIA sources, 252 Cf, must be replaced every 8-10 years due to its relatively short half-life (2.645 ± 0.008 y). In the past, each newly purchased 252 Cf source has been calibrated at NIST using the Mn-bath technique prior to shipping to LANL. However, because of COVID-19 complications, the most recently acquired 252 Cf source (FTC-CF-7167) has been stored at LANL pending approval to ship to NIST for calibration. Due to the considerable expense in transporting the source to and from NIST, this TBD was written to demonstrate that new sources can be accurately calibrated via intercomparison measurements with older NIST-calibrated 252 Cf sources. It had been previously noted that such measurements yielded emission rates that agreed very well with the official rates established by NIST

252cf↗

Calendar Year 2020 Post-Closure Monitoring Report for Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Underground Test Area, Nevada National Security Site, Nevada (Rev. 1)

This report presents the results of monitoring conducted for water quality, water levels, and institutional controls in calendar year (CY) 2020 by the U.S. Department of Energy (DOE), Environmental Management (EM) Nevada Program’s Underground Test Area (UGTA) Activity at Corrective Action Unit (CAU) 99, Rainier Mesa/Shoshone Mountain (RM/SM), at the Nevada National Security Site (NNSS), Nevada. This report also presents analytical laboratory results (including results of quality assurance/quality control samples, such as field duplicates [FDs]), and verification of use restrictions (URs), institutional controls, and water usage. Groundwater samples were collected; water levels were measured; and well site surveillance was conducted in support of the Underground Test Area Closure Report (CR) for Corrective Action Unit 99: Rainier Mesa/Shoshone Mountain, Nevada National Security Site, Nevada (DOE/EMNV, 2020). Rainier Mesa (RM) was the site of 61 underground nuclear tests, and Shoshone Mountain (SM) was the site of 6 underground nuclear tests. As a result of these activities, which took place from 1957 to 1992, radionuclides (RNs) were released in the subsurface in the vicinity of the detonations. These 67 underground nuclear tests are associated with 66 specific corrective action site (CAS) numbers, as listed in the Federal Facility Agreement and Consent Order (FFACO) (1996, as amended). Two tests, HURON LANDING and DIAMOND ACE (conducted simultaneously), are included within one CAS. The CR (DOE/EMNV, 2020) establishes the regulatory boundaries and regulatory boundary objectives, monitoring program, UR boundaries and URs, and other institutional controls agreed to by EM Nevada Program and the Nevada Division of Environmental Protection (NDEP) for closure of CAU 99. Regulatory boundaries for the RM/SM CAU were established to protect receptors of groundwater from RN contamination within the three downgradient groundwater basins that receive recharge from RM. The SM regulatory boundary was established to verify that RN contamination does not reach the lower carbonate aquifer below SM. The UR boundaries were established based on contaminant simulation forecasts from the flow and transport simulations with consideration of site-specific topographical controls. The URs associated with the UR boundaries were identified to protect onsite workers and the public from inadvertent exposure to contaminated groundwater as forecasted to occur assuming current conditions. The UR is intended to restrict activities that might expose workers to contaminated groundwater within the UR area. In addition to the URs, other institutional controls are established to monitor and limit access to groundwater. These include federal ownership and management in perpetuity, controlled access of the NNSS and surrounding areas, and reporting water use on the NNSS and surrounding hydrographic basins.

54 ENVIRONMENTAL SCIENCES↗