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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 163 records · Page 9

Human factors assessments of the STS-57 SpaceHab-1 mission

SpaceHab-1 (STS-57) was the first of six scheduled Commercial Middeck Augmentation Module (CMAM) missions seeking to offer entrepreneurial companies an opportunity to use the resource of microgravity. The SpaceHab module, which occupies about one-fourth of the payload bay, is approximately 2-3/4 meters (9 feet) long and 4 meters (13.5 feet) in diameter. It provides a shirt-sleeve working environment and contains the storage space equivalent of 50 middeck lockers, considerably over and above the number of experiments that can be carried in the orbiter middeck alone. A modified Spacelab tunnel links the SpaceHab module to the middeck. While in orbit, the orbiter payload bay doors remain open, exposing the padded exterior of the lab and tunnel to space until preparation for reentry at the end of the flight. The crew for SpaceHab-1 was comprised of four males and two females, each of whom participated in some part of the human factors assessment (HFA) evaluation. The HFA was one of over twenty experiments manifested on this maiden flight of the SpaceHab module. HFA consisted of HFA-EPROC, HFA-LIGHT, HFA-SOUND, HFA-QUEST, and HFA-TRANS. The goal of HFA-EPROC was to assess the advantages and disadvantages of paper versus computer presentation for procedural tasks. The next two evaluations investigated the module's lighting and acoustic environment. HFA-TRANS sought to evaluate the design of the SpaceHab tunnel and to characterize translation through it. HFA-QUEST represented a consolidation of the in-flight questions generated by the HFA principal investigators involved in the acoustic, lighting, and translation studies.

Mount, Frances E.↗

RAID Unbound: Storage Fault Tolerance in a Distributed Environment

Mirroring, data replication, backup, and more recently, redundant arrays of independent disks (RAID) are all technologies used to protect and ensure access to critical company data. A new set of problems has arisen as data becomes more and more geographically distributed. Each of the technologies listed above provides important benefits; but each has failed to adapt fully to the realities of distributed computing. The key to data high availability and protection is to take the technologies' strengths and 'virtualize' them across a distributed network. RAID and mirroring offer high data availability, which data replication and backup provide strong data protection. If we take these concepts at a very granular level (defining user, record, block, file, or directory types) and them liberate them from the physical subsystems with which they have traditionally been associated, we have the opportunity to create a highly scalable network wide storage fault tolerance. The network becomes the virtual storage space in which the traditional concepts of data high availability and protection are implemented without their corresponding physical constraints.

Ritchie, Brian↗

A Parallel Pipelined Renderer for the Time-Varying Volume Data

This paper presents a strategy for efficiently rendering time-varying volume data sets on a distributed-memory parallel computer. Time-varying volume data take large storage space and visualizing them requires reading large files continuously or periodically throughout the course of the visualization process. Instead of using all the processors to collectively render one volume at a time, a pipelined rendering process is formed by partitioning processors into groups to render multiple volumes concurrently. In this way, the overall rendering time may be greatly reduced because the pipelined rendering tasks are overlapped with the I/O required to load each volume into a group of processors; moreover, parallelization overhead may be reduced as a result of partitioning the processors. We modify an existing parallel volume renderer to exploit various levels of rendering parallelism and to study how the partitioning of processors may lead to optimal rendering performance. Two factors which are important to the overall execution time are re-source utilization efficiency and pipeline startup latency. The optimal partitioning configuration is the one that balances these two factors. Tests on Intel Paragon computers show that in general optimal partitionings do exist for a given rendering task and result in 40-50% saving in overall rendering time.

Chiueh, Tzi-Cker↗

Efficient Encoding and Rendering of Time-Varying Volume Data

Visualization of time-varying volumetric data sets, which may be obtained from numerical simulations or sensing instruments, provides scientists insights into the detailed dynamics of the phenomenon under study. This paper describes a coherent solution based on quantization, coupled with octree and difference encoding for visualizing time-varying volumetric data. Quantization is used to attain voxel-level compression and may have a significant influence on the performance of the subsequent encoding and visualization steps. Octree encoding is used for spatial domain compression, and difference encoding for temporal domain compression. In essence, neighboring voxels may be fused into macro voxels if they have similar values, and subtrees at consecutive time steps may be merged if they are identical. The software rendering process is tailored according to the tree structures and the volume visualization process. With the tree representation, selective rendering may be performed very efficiently. Additionally, the I/O costs are reduced. With these combined savings, a higher level of user interactivity is achieved. We have studied a variety of time-varying volume datasets, performed encoding based on data statistics, and optimized the rendering calculations wherever possible. Preliminary tests on workstations have shown in many cases tremendous reduction by as high as 90% in both storage space and inter-frame delay.

CODING↗

Isosurface Extraction in Time-Varying Fields Using a Temporal Hierarchical Index Tree

Many high-performance isosurface extraction algorithms have been proposed in the past several years as a result of intensive research efforts. When applying these algorithms to large-scale time-varying fields, the storage overhead incurred from storing the search index often becomes overwhelming. this paper proposes an algorithm for locating isosurface cells in time-varying fields. We devise a new data structure, called Temporal Hierarchical Index Tree, which utilizes the temporal coherence that exists in a time-varying field and adoptively coalesces the cells' extreme values over time; the resulting extreme values are then used to create the isosurface cell search index. For a typical time-varying scalar data set, not only does this temporal hierarchical index tree require much less storage space, but also the amount of I/O required to access the indices from the disk at different time steps is substantially reduced. We illustrate the utility and speed of our algorithm with data from several large-scale time-varying CID simulations. Our algorithm can achieve more than 80% of disk-space savings when compared with the existing techniques, while the isosurface extraction time is nearly optimal.

Shen, Han-Wei↗

Collapsible Towers

NASA needed a means of orbiting a large radio telescope antenna. Astro Research Corporation developed a new structure that was strong, lightweight, folded into a small storage space, and could be erected by rotation. Later they adapted it to commercial use. Today the "Astromast" tower consists of tubular aluminum alloy and stainless steel members that deploy into small three-sided bays, each made rigid by six diagonal cables. All joints are flexible to permit folding and unfolding. Tower packs into container 5% of its height, can be erected without tools and is reusable. Tower has won "Design of the Year" award from Machine Design. Variations include portable emergency bridges and commercial scaffolding.

Source record↗

Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales

For long-duration in-space storage of cryogenic propellants, an axial jet mixer is one concept for controlling tank pressure and reducing thermal stratification. Extensive ground-test data from the 1960s to the present exist for tank diameters of 10 ft or less. The design of axial jet mixers for tanks on the order of 30 ft diameter, such as those planned for the Ares V Earth Departure Stage (EDS) LH2 tank, will require scaling of available experimental data from much smaller tanks, as well designing for microgravity effects. This study will assess the ability for Computational Fluid Dynamics (CFD) to handle a change of scale of this magnitude by performing simulations of existing ground-based axial jet mixing experiments at two tank sizes differing by a factor of ten. Simulations of several axial jet configurations for an Ares V scale EDS LH2 tank during low Earth orbit (LEO) coast are evaluated and selected results are also presented. Data from jet mixing experiments performed in the 1960s by General Dynamics with water at two tank sizes (1 and 10 ft diameter) are used to evaluate CFD accuracy. Jet nozzle diameters ranged from 0.032 to 0.25 in. for the 1 ft diameter tank experiments and from 0.625 to 0.875 in. for the 10 ft diameter tank experiments. Thermally stratified layers were created in both tanks prior to turning on the jet mixer. Jet mixer efficiency was determined by monitoring the temperatures on thermocouple rakes in the tanks to time when the stratified layer was mixed out. Dye was frequently injected into the stratified tank and its penetration recorded. There were no velocities or turbulence quantities available in the experimental data. A commercially available, time accurate, multi-dimensional CFD code with free surface tracking (FLOW-3D from Flow Science, Inc.) is used for the simulations presented. Comparisons are made between computed temperatures at various axial locations in the tank at different times and those observed experimentally. The affect of various modeling parameters on the agreement obtained are assessed.

Breisacher, Kevin↗

Experimental and Numerical Investigation of Reduced Gravity Fluid Slosh Dynamics for the Characterization of Cryogenic Launch and Space Vehicle Propellants

As space programs increasingly investigate various options for long duration space missions the accurate prediction of propellant behavior over long periods of time in microgravity environment has become increasingly imperative. This has driven the development of a detailed, physics-based understanding of slosh behavior of cryogenic propellants over a range of conditions and environments that are relevant for rocket and space storage applications. Recent advancements in computational fluid dynamics (CFD) models and hardware capabilities have enabled the modeling of complex fluid behavior in microgravity environment. Historically, launch vehicles with moderate duration upper stage coast periods have contained very limited instrumentation to quantify propellant stratification and boil-off in these environments, thus the ability to benchmark these complex computational models is of great consequence. To benchmark enhanced CFD models, recent work focuses on establishing an extensive experimental database of liquid slosh under a wide range of relevant conditions. In addition, a mass gauging system specifically designed to provide high fidelity measurements for both liquid stratification and liquid/ullage position in a micro-gravity environment has been developed. This pUblication will summarize the various experimental programs established to produce this comprehensive database and unique flight measurement techniques.

Walls, Laurie K.↗

GES DISC Datalist Enables Easy Data Selection For Natural Phenomena Studies

In order to investigate and assess natural hazards such as tropical storms, winter storms, volcanic eruptions, floods, and drought in a timely manner, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has been developing an efficient data search and access service. Called "Datalist," this service enables users to acquire their data of interest "all at once," with minimum effort. A Datalist is a virtual collection of predefined or user-defined data variables from one or more archived data sets. Datalists are more than just data. Datalists effectively provide users with a sophisticated integrated data and services package, including metadata, citation, documentation, visualization, and data-specific services (e.g., subset and OPeNDAP), all available from one-stop shopping. The predefined Datalists, created by the experienced GES DISC science support team, should save a significant amount of time that users would otherwise have to spend. The Datalist service is an extension of the new GES DISC website, which is completely data-driven. A Datalist, also known as "data bundle," is treated just as any other data set. Being a virtual collection, a Datalist requires no extra storage space.

natural hazards↗

GES DISC Datalist Enables Easy Data Selection for Natural Phenomena Studies

In order to investigate and assess natural hazards such as tropical storms, winter storms, volcanic eruptions, floods, and drought in a timely manner, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has been developing an efficient data search and access service. Called Datalist, this service enables users to acquire their data of interest all at once, with minimum effort. A Datalistis a virtual collection of predefined or user-defined data variables from one or more archived data sets. Datalistsare more than just data. Datalistseffectively provide users with a sophisticated integrated data and services package, including metadata, citation, documentation, visualization, and data-specific services (e.g., subset and OPeNDAP), all available from one-stop shopping. The predefined Datalists, created by the experienced GES DISC science support team, should save a significant amount of time that users would otherwise have to spend. The Datalistservice is an extension of the new GES DISC website, which is completely data-driven. A Datalist, also known as data bundle, is treated just as any other data set. Being a virtual collection, a Datalistrequires no extra storage space.

Earth events↗

Establishing the Feasibility of the Centrifugal Nuclear Thermal Rocket

The Centrifugal Nuclear Thermal Rocket (CNTR) is a Nuclear Thermal Propulsion (NTP) concept designed to heat propellant directly by the reactor fuel. The primary difference between the CNTR concept and traditional NTP systems is that rather than using traditional solid fuel elements, the CNTR uses liquid fuel with the liquid contained in rotating cylinders by centrifugal force. If the concept can be successfully realized, the CNTR would have a high specific impulse (~1800 s) at high thrust, which may enable viable near-term human Mars exploration by reducing round-trip times to ~420 days. The CNTR could also use storable propellants such as ammonia, methane, or hydrazine at an Isp of ~900 s, enabling long-term in-space storage of a dormant system. Significant engineering challenges must be addressed to establish the technical viability of the CNTR, and the plan for addressing these engineering challenges is the subject of this paper.

Dale Thomas↗

Early Progress Toward the Feasibility of the Centrifugal Nuclear Thermal Rocket

The Centrifugal Nuclear Thermal Rocket (CNTR) is a Nuclear Thermal Propulsion (NTP) concept designed to heat propellant directly by the reactor fuel. The primary difference between the CNTR concept and traditional NTP systems is that rather than using traditional solid fuel elements, the CNTR uses liquid fuel with the liquid contained in rotating cylinders by centrifugal force. If the concept can be successfully realized, the CNTR would have a high specific impulse (~1800 seconds) at high thrust, which may enable (i) viable near-term human Mars exploration by reducing round-trip times to 420 days and (ii) direct injection orbits for scientific missions to the Solar System outer planets and potentially Kuiper Belt objects. The CNTR could also use storable propellants such as ammonia, methane, or hydrazine at an Isp of ~900 seconds, enabling long-term in-space storage of a dormant system. Significant engineering challenges must be addressed to establish the technical viability of the CNTR. Research is presently underway to determine resolutions for these engineering challenges. In particular, research has begun on the analytical modeling and simulation of the two-phase heat transfer between the liquid metallic uranium fuel and the gaseous propellant. A paper was presented at the 2021 IAC which described these challenges and the study plan to address them. This paper describes the analytical and experimental progress to date toward resolving these challenges and establishing the engineering feasibility of the CNTR technology

High Performance Nuclear Thermal Propulsion NTP SN↗

Reduction of the Equivalent System Mass of a Trash Compaction Processing System Designed for Human Spaceflight Waste Management by Improving its Thermal Efficiency

A spacecraft life support system has been under development at NASA called the Trash Compaction Processing System that manages trash generated on human spaceflight missions. The trash composite typically includes components such as plastic pouches that contain wet food and drinks, used cotton clothing such as underwear and T-shirts, exercise clothing, used washcloths, expended deodorant containers, adhesive tapes, plastic bubble wrap, and other sundry items. The system uses compaction in combination with heat to turn the waste composite into a sturdy and well-defined shape, typically called a tile, which maintains structural integrity and makes the most efficient use of storage space. In addition to reducing the volume of the trash, the Trash Compaction Processing System removes water from the trash. The heating and removal of water from the trash renders it safe against microbial activity. This paper primarily focuses on work aimed at reducing the Equivalent System Mass of a Trash Compaction Processing System via a focus on improving the system’s thermal efficiency.

TCPS↗

Reduction of Equivalent System Mass of a Trash Compaction Processing System with an Emphasis on Improved Thermal Efficiency

A spacecraft life support system has been under development at NASA called the Trash Compaction Processing System that manages trash generated on human spaceflight missions. The trash composite typically includes components such as plastic pouches that contain wet food and drinks, used cotton clothing such as underwear and T-shirts, exercise clothing, used washcloths, expended deodorant containers, adhesive tapes, plastic bubble wrap, and other sundry items. The system uses compaction in combination with heat to turn the waste composite into a sturdy and well-defined shape, typically called a tile, which maintains structural integrity and makes the most efficient use of storage space. In addition to reducing the volume of the trash, the Trash Compaction Processing System removes water from the trash. The heating and removal of water from the trash renders it safe against microbial activity. This paper primarily focuses on work aimed at reducing the Equivalent System Mass of a Trash Compaction Processing System via a focus on improving the system’s thermal efficiency.

Trash Compaction Processor↗

Supporting adaptive shared cache management

Embodiment of this disclosure provides a mechanism to use a portion of an inactive processing element's private cache as an extended last-level cache storage space to adaptively adjust the size of shared cache. In one embodiment, a processing device is provided. The processing device comprising a cache controller is to identify a cache line to evict from a shared cache. An inactive processing core is selected by the cache controller from a plurality of processing cores associated with the shared cache. Then, a private cache of the inactive processing core is notified of an identifier of a cache line associated with the shared cache. Thereupon, the cache line is evicted from the shared cache to install in the private cache.

97 MATHEMATICS AND COMPUTING↗

DENOVA: Deduplication Extended NOVA File System

This paper shows mathematically and experimentally that inline deduplication is not suitable for file systems on ultra-low latency Intel Optane DC PM devices in terms of performance, and proposes DeNova, an offline deduplication specially designed for log-structured NVM file systems such as NOVA. DeNova offers high-performance and low-latency I/O processing and executes deduplication in the background without interfering with foreground I/Os. DeNova employs DRAM-free persistent deduplication metadata, favoring CPU cache line, and ensures failure consistency on any system failure. We implement DeNova in the NOVA file system. Evaluation with DeNova confirms a negligible performance drop of baseline NOVA of less than 1%, while gaining high storage space savings. Extensive experiments show DeNova is failure consistent in all failure scenario cases.

Khan, Awais↗

Basin Management of Geologic CO2 Storage: Effect of Well Spacing on CO2 Plume and Pressure Interference

This is the conference paper accompanying an oral presentation made at the Society of Petroleum Engineers (SPE) Western Regional Meeting (WRM) held in Bakersfield, California, April 26–28, 2022. The paper provides the results of a basin-scale CO2 storage modeling project investigating subsurface pressure interference among CO2 injection wells located in proximity to each other.

Wijaya, Nur↗

Open-cycle thermochemical energy storage for building space heating: Practical system configurations and effective energy density

Salt-hydrate thermochemical materials (TCM) are promising candidates for energy storage systems for building space heating due to their high theoretical energy density and the need for low regeneration temperature. However, water vapor is required to drive the hydration process of the TCM reactor, which poses a challenge during winter when water vapor is typically scarce. Using indoor air directly lowers the building's humidity to an unconformable level in practice, while the cold outdoor air contains limited moisture. Here we consider different integration strategies for open-cycle TCM reactors in buildings and develop a model to simulate their thermal performance across diverse buildings and climates, specifically for building space heating. The potential energy densities and the levelized cost of storage of the TCM reactor are evaluated in practical scenarios to demonstrate the load-shifting potential of TCM systems for heating applications. We use a strontium chloride (SrCl 2 )-based composite as the baseline and explore the impact of various reactor and material changes to the energy density and levelized cost of storage.

25 ENERGY STORAGE↗