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At least 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

The Exploitation of Data Reduction for Visualization

The disparity between the computational speed and storage bandwidth, as demonstrated in Figure 1, is a well known problem that grows with each successive generation. The visualization community is principally responding to this issue by using in situ to reduce which data must be written to storage. However, other communities are taking different, possibly complementary approaches. In particular, data compression is a common general approach to reduce storage demands. Data compression technologies are typically not designed with post processing in mind. The principal metrics measured are compression ratio, the improved bandwidth to storage, and the error introduced. It is assumed that data is inflated to its full size before any post processing can happen. Although when talking about bandwidth disparities, HPC’s dirty little secret is that no part of the memory nor interconnect hardware is increasing at the rate of computation. For example, the Summit supercomputer has a peak computation rate almost 10 times its predecessor, Titan, but only about 4 times the memory, less than twice the aggregate memory bandwidth, and almost no improvement in the interconnect bisection bandwidth. Naively inflating data for post processing does not help with limitations in the memory and interconnect systems.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Powertrain Performance and Total Cost of Ownership Analysis for Class 8 Yard Tractors and Refuse Trucks

Advanced powertrain technologies, specifically fuel cell electric powertrains, have gained attention as viable alternatives for medium- and heavy-duty (M/HD) vehicles. However, it is unclear how these alternative powertrain vehicles stack up against their diesel counterparts in terms of performance and total cost of ownership (TCO). Furthermore, there are vehicle segments within the M/HD sector that have remained unstudied for fuel cell electric applications. This analysis aims to provide a comparative scoping-level TCO and performance analysis for two heavy-duty vocation vehicles (Class 8 U.S. port-side yard tractor and Class 8 U.S.-based refuse truck) for both conventional diesel and heavy-duty fuel cell electric (HDFC) powertrains. The refuse truck analysis also considered compressed natural gas powertrains (CNG) for comparison. The analysis includes seven timeframes (2020, 2025, 2030, 2035, 2040, 2045, and 2050) for comparison. This simplified TCO analysis includes only direct costs (fuel price, glider purchase price, and operating & maintenance costs) and excludes any associated indirect cost (e.g., dwell time costs and other opportunity based costs). Representative drive cycles for each vehicle were based on on-board GPS logged data and chosen by the analysis team to represent average, non-extreme driving conditions. At the time the analysis was performed, the Inflation Reduction Act was not in effect and therefore any potential subsidies and future cost reductions enacted under the Inflation Reduction Act were not included. Based on the operational setpoints used in this analysis, HDFC powertrains for both yard tractors and refuse trucks have the potential to achieve TCO advantages over conventional diesel powertrains (and CNG for refuse truck applications) in the near- to mid-term future while meeting the necessary duty cycle performance requirements. Yard tractors and refuse trucks spend a significant amount of time operating at low speeds, with long durations of idling, and experience numerous start/stop occurrences. These operational characteristics favor fuel cell performance as fuel cells operate with higher efficiencies at lower percentages of total power output. Conversely, conventional diesel and CNG engines are most efficient at higher percentages of total power output. This helps HDFC powered yard tractors and refuse trucks realize improved fuel economy when compared to their diesel counterparts, which helps reduce total fuel costs and therefore, total TCO. The analysis demonstrates that fuel prices play a significant role in determining TCO for each vehicle and should remain an R&D focus area. Overall, under the analysis' specified conditions, HDFC yard tractors have the potential to achieve cost parity with diesel yard tractors as early as 2025. For refuse trucks, HDFC refuse trucks have the potential to achieve cost parity with diesel and CNG refuse trucks in 2030 and 2040, respectively.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Advanced Fuel Cycle Cost Basis Report: Module D1-1: Uranium-based Ceramic LWR Fuel Fabrication (Rev.2)

Cost module on LWR fuel fabrication to accompany the Advanced Fuel Cycle Cost Basis Report. In this update, we are adding detailed life cycle cost data and a calculated, levelized fabrication cost derived from a non-proprietary bottom-up estimate prepared in 1978 by Oak Ridge National Laboratory (ORNL) (Judkins and Olsen 1978a). In 2018, the 1978 ORNL estimate was escalated by SA&I authors to 2017 USD using factors that represent inflation, escalation above inflation typical of nuclear projects, and the effects of more stringent safety and environmental regulations. In this FY-21 document, the $/kgU results in 2017 USD from the unpublished 2018 interim study (Williams and Ganda 2018) can be escalated to 2020 USD using a factor of 1.052. The literature-based unit cost (or price) data from previous (2004–2017) AFC-CBRs are escalated to 2020 USD using factors from Chapter 8 of the main FY-21 AFC-CBR document. This data, in addition to the results of the updated bottom-up estimate, are used to define the “what-it-takes” (WIT) range for the unit fabrication costs for conventional ceramic UOX light-water reactor (LWR) fuel. This FY-23 document also includes calculated unit costs for accident-tolerant LWR fuels (ATFs) of three different types. Some of these fuels constitute a ceramic pelletized form with fuel meat uranium compounds other than UO2 (a.k.a.,. UOX), thus the change in the title of this module in which the word “UO2” is changed to “Uranium-based Ceramic.”

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Lyapunov and Clearing Timescales in Planetary Chaotic Zones

Debris disks in planetary systems are known to possess gaps “opened” by planets in their close-to-coorbital neighborhoods; the gaps are free from low-mass material such as planetesimals. We consider the escape process of the initially zero-eccentric particles from the gap zone in a scenario consisting of two basic consequent stages: (1) the particle orbit's eccentricity is inflated, while its specific energy is relatively constant, and (2) the particle orbit's semimajor axis is inflated, while its specific angular momentum is relatively constant. During the first stage, the chaotic transport (diffusion) proceeds along the “staircase” of (p + 1):p (with integer p ≫ 1) overlapping particle–planet resonances, and during the second stage, it proceeds along the p:1 particle–planet resonance staircase. A specialized two-dimensional area-preserving map (a “tokamap” version) is derived to describe the first stage, while a multiharmonic Kepler map theory is used to describe the second stage. We derive the μ (mass parameter) scaling for the clearing timescale in the planetary chaotic zone. At small μ, it turns out to be inverse-quadratic in μ. The μ scaling for the Lyapunov timescale inside the gap is also derived. The derived scalings are in qualitative agreement with available numerical-experimental data.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Characterization of Low-mass Companions to Kepler Objects of Interest Observed with APOGEE-N

We report the characterization of 28 low-mass (0.02 M ⊙ ≤ M 2 ≤ 0.25 M ⊙ ) companions to Kepler objects of interest (KOIs), eight of which were previously designated confirmed planets. These objects were detected as transiting companions to Sunlike stars (G and F dwarfs) by the Kepler mission and are confirmed as single-lined spectroscopic binaries in the current work using the northern multiplexed Apache Point Observatory Galactic Evolution Experiment near-infrared spectrograph (APOGEE-N) as part of the third and fourth Sloan Digital Sky Surveys. We have observed hundreds of KOIs using APOGEE-N and collected a total of 43,175 spectra with a median of 19 visits and a median baseline of ~1.9 yr per target. We jointly model the Kepler photometry and APOGEE-N radial velocities to derive fundamental parameters for this subset of 28 transiting companions. The radii for most of these low-mass companions are overinflated (by ~10%) when compared to theoretical models. Tidally locked M dwarfs on short-period orbits show the largest amount of inflation, but inflation is also evident for companions that are well separated from the host star. We demonstrate that APOGEE-N data provide reliable radial velocities when compared to precise high-resolution spectrographs that enable detailed characterization of individual systems and the inference of orbital elements for faint (H > 12) KOIs. The data from the entire APOGEE-KOI program are public and present an opportunity to characterize an extensive subset of the binary population observed by Kepler.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1966

Flexible fastener effects airtight material closure

Flexible tube inserted into a 3/4-round strip receptacle inflates to form an airtight material fastener. Inflation is done with a carbon dioxide cartridge and deflation by a manually operated release valve. Device has potential use in space suits, underwater suits, and other protective clothing.

Nay, D. L.↗
NASA NTRS1971

Proposed techniques for launching instrumented balloons into tornadoes

A method is proposed to introduce instrumented balloons into tornadoes by means of the radial pressure gradient, which supplies a buoyancy force driving to the center. Presented are analytical expressions, verified by computer calculations, which show the possibility of introducing instrumented balloons into tornadoes at or below the cloud base. The times required to reach the center are small enough that a large fraction of tornadoes are suitable for the technique. An experimental procedure is outlined in which a research airplane puts an instrumented, self-inflating balloon on the track ahead of the tornado. The uninflated balloon waits until the tornado closes to, typically, 750 meters; then it quickly inflates and spirals up and into the core, taking roughly 3 minutes. Since the drive to the center is automatically produced by the radial pressure gradient, a proper launch radius is the only guidance requirement.

Grant, F. C.↗
NASA NTRS1971

Subsonic and transonic pressure distributions around a bluff afterbody in the wake of a 120 deg cone for various separation distances

A wind-tunnel investigation was conducted at free-stream Mach numbers from 0.20 to 1.00 and Reynolds numbers, based on maximum afterbody diameter, from 2.25 million to 6.90 million on solid models of an attached inflatable decelerator (AID) concept. Tests were conducted to obtain static and ram surface pressure distributions about the basic shapes and at various separation distances between the 120 deg conical forebody and the inflated afterbody shape. The resulting data were used to study the feasibility of extracting a payload from a conical forebody by means of an AID.

Sawyer, J. W.↗
NASA NTRS1972

Aircraft tire behavior during high-speed operations in soil

An investigation to determine aircraft tire behavior and operating problems in soil of different characteristics was conducted at the Langley landing-loads track with a 29 x 110.0-10, 8-ply-rating, type 3 tire. Four clay test beds of different moisture content and one sand test bed were used to explore the effects on axle drag loads developed during operation at different tire inflation pressures in free rolling, locked-wheel braking, and yawed (cornering) modes, all at forward speeds up to 95 knots. The test results indicated a complicated drag-load--velocity relationship, with a peak in the drag-load curve occurring near 40 knots for most test conditions. The magnitude of this peak was found to vary with tire inflation pressure and soil character and, in certain cases, might prove large enough to make take-off hazardous.

Leland, T. J. W.↗
NASA NTRS1972

Nonapplicability of linear finite element programs to the stress analysis of tires

A static finite element stress analysis of an inflated radial car tire was carried out. The deformed shape of the sidewall presents outward bulging. The analysis of a homogeneous isotropic toroidal shell shows that the problem is common to all solids of this type. The study suggests that the geometric stiffness due to the inflation pressure has to be taken into account. Also, the resulting large displacements make it necessary for the geometry to be updated at each load step.

Durand, M.↗
NASA NTRS1972

The configuration of the geomagnetic field.

Spherical harmonic representations of the geomagnetic field based on ground-based and low-altitude spacecraft measurements adequately describe the field within several earth radii of the earth's surface. As the internal field decreases with increasing distance from the earth, external field sources become relatively more important. In the region of 3 to 6 earth radii, magnetospheric plasma inflates the field lines and decreases the field strength by an amount which is typically 10's of gammas and occasionally 100's of gammas. At greater distances on the day side of the earth, the solar wind compresses the field and produces equatorial field strengths of approximately 60 gammas at 10 earth radii. Field lines near the magnetopause intersect the earth at approximately 78 deg latitude in the sunward hemisphere. The solar wind drags high latitude field lines away from the earth in the night hemisphere forming the geomagnetic tail and neutral sheet. Asymmetric field inflation in the magnetosphere occurs during magnetic disturbances with the largest effects concentrated in the evening quadrant. The tail configuration can deviate substantially from the average configuration during magnetic disturbances.

Fairfield, D. H.↗
NASA NTRS1973

Parachute gore shape and flow visualization during transient and steady-state conditions.

Single parachute gore segments were tested in an experimental wind tunnel having a unique 'V' splitter plate test section with a glass panel on the near side and a grid of orifices for smoke injection on the back panel. The parachute gore shape and flow patterns were viewed in cross section during the inflation process and also during changing flow conditions as would occur with rapid reduction of payload weight. Observations of flow during inflation revealed a transient internal counterflow and the formation and degeneration of several trailing vortices. Gore shapes observed compared well with those of free flight.

Dereng, V. G.↗
NASA NTRS1973

A systematic experimental investigation of significant parameters affecting model tire hydroplaning

The results of a comprehensive parametric study of model and small pneumatic tires operating on a wet surface are presented. Hydroplaning inception (spin down) and rolling restoration (spin up) are discussed. Conclusions indicate that hydroplaning inception occurs at a speed significantly higher than the rolling restoration speed. Hydroplaning speed increases considerably with tread depth, surface roughness and tire inflation pressure of footprint pressure, and only moderately with increased load. Water film thickness affects spin down speed only slightly. Spin down speed varies inversely as approximately the one-sixth power of film thickness. Empirical equations relating tire inflation pressure, normal load, tire diameter and water film thickness have been generated for various tire tread and surface configurations.

Wray, G. A.↗
NASA NTRS1973

Transequatorial effects of sea-surface temperature anomalies in a global general circulation model

An effort is made to describe the development of the model atmosphere's response to the sea-surface temperature (SST) anomalies in terms of their effect on the pole-to-pole meridional profile of the zonal mean 600-mb surface, which represents approximately the middle level of the model. The initial effect of a positive SST anomaly located in extratropical latitudes of the Pacific Ocean is found to be an inflation of the isobaric surfaces, relative to a control run, within the latitude band of the warm pool. In experiments with a North Pacific warm pool, the inflation continued for about 3 weeks in both winter and summer.

Spar, J.↗
NASA NTRS1974

Effects of an anti-G suit on the hemodynamic and renal responses to positive /+Gz/ acceleration

The effects of the currently used U.S. Air Force (CSU-12/P) anti-G suit on renal function during positive radial acceleration (+Gz) were assessed in seven normal male subjects in balance on a 200 meq sodium diet. Following suit inflation in the seated position, +2.0 Gz for 30 min resulted in a decrease in the rate of sodium excretion from 125 plus or minus 19 to 60 plus or minus 14 microeq/min, which persisted during a 25-min recovery period. Fractional excretion of sodium also decreased significantly during +Gz. The magnitude of the antinatriuresis was indistinguishable from that observed during +Gz without suit inflation. In contrast to the antinatriuresis observed during centrifugation without suit, however, the antinatriuresis with suit was mediated primarily by an enhanced tubular reabsorption of sodium.

Shubrooks, S. J., Jr.↗
NASA NTRS1974

Flight tests of Viking parachute system in three Mach number regimes. 2: Parachute test results

Tests of the Viking 16.15-meter nominal-diameter disk-gap-band parachute were conducted at Mach number and dynamic pressure conditions which bracketed the range postulated for the Viking '75 mission to Mars. Parachutes were deployed at supersonic, transonic, and subsonic speeds behind a simulated Viking entry capsule. All parachutes successfully deployed, inflated, and exhibited sufficient drag and stability for mission requirements. Basic parachute data including loads, drag coefficients, pull-off angles, and canopy area ratios are presented. Trajectory reconstruction and onboard camera data methods were combined to yield continuous histories of both parachute and test-vehicle angular motions which are presented for the period from parachute deployment through steady inflation.

Bendura, R. J.↗