Performance of disk-gap-band, ringsail, and cross parachutes at low earth altitudes
Parachutes for low density atmospheres, describing low and high altitude test results
Eckstrom, C. V.↗
SEARCH · Engineering Papers
Results for “Performance Gap”
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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Event-to-Video Conversion for Overhead Object Detection
Collecting overhead imagery using an event camera is desirable due to the energy efficiency of the image sensor compared to standard cameras. However, event cameras complicate downstream image processing, especially for complex tasks such as object detection. In this paper, we investigate the viability of event streams for overhead object detection. We demonstrate that across a number of standard modeling approaches, there is a significant gap in performance between dense event representations and corresponding RGB frames. We establish that this gap is, in part, due to a lack of overlap between the event representations and the pre-training data that the object detectors were initially trained on through a number of experiments. Then, apply an off-the-shelf event-to-video conversion tool that converts event streams into gray-scale video to close this gap. We demonstrate that this approach results in a large performance increase, outperforming even event-specific object detection techniques on our overhead target task. These results suggest that better aligning event representations with existing large pre-trained models may result in greater short-term performance gains compared to end-to-end event-specific architectural improvements.
machine learning (ML), computer vision, Neuromorph↗
Integrating Human Performance Measures into Space Operations: Beyond Our Scheduling Capabilities?
Current planning and scheduling software tools for International Space Station (ISS) support different flight controller teams as they plan daily space operations. Planning and scheduling tools capabilities include integrating digitized ISS state inputs, evaluating their expected future states, and propagating them over time. Extensive, custom-made computational models of operations, of objectives, and of operational constraints help ISS flight controllers identify where scheduled events violate constraints. Based on the current capabilities of these tools, this paper proposes how human performance measures could be better integrated into planning and scheduling tools for space mission operations. Future integration of human performance measures could be applied to state inputs (in this case, the astronaut’s state) and to modeling human performance operational constraints & operational objectives (i.e., assigned activities) with parameters that are relevant to human performance measures. Gaps between the state-of-the-art for human performance modeling and planning tools for future exploration missions are identified.
space operations↗
Revealing optoelectronic and transport properties of potential perovskites Cs 2 PdX 6 (X = Cl, Br): A probe from density functional theory (DFT)
Metal-halide perovskites are rapidly emerging crystalline materials that are reasonably preferred as leading aspirant for applications in optoelectronic and thermoelectric devices. In this paper, we have thoroughly reviewed and performed calculations to reveal optoelectronic and transport properties for a potential newcomer, Cs 2 PdX 6 (X = Cl, Br) termed as Cesium Palladium Halides (CPH). Outcome of present computations are compared with available results and a reasonable agreement is recorded. Energy band gap computations performed reveal indirect band gap of 2.29 eV for Cs 2 PdCl 6 , which substantially reduces to 1.22 eV when ‘Cl’ is replaced by ‘Br’. Optical absorption spectra investigations performed here, in the energy range from 3 to 5 eV confirms effective utilization of these compounds in solar cells and other optoelectronic applications. In addition, the transport properties computations performed using semi-classical Boltzmann theory, shows constant pattern of thermo power near ambient temperature range (200–500 K), which admits possible utilization of these compounds as low temperature thermoelectric materials. Performed ZT calculations demonstrates reasonably good thermoelectric performance for both materials, as there exist minor variation (0.1) in the values over wide temperature ranges i.e. from 100 to 800 K. Further, detailed analysis of transport properties predicts p-type semiconducting nature of the present series of materials.
Bhamu, K. C.↗
Northstar Mo99 Window Tests
Tests were completed for window to “first disk” (actually a steel plate for these expariments) gaps of 20 mil as per design gap as well as 10 mil and 30 mil gaps to span the range of possible variations. With possible disk distortion in beam, another test with 0 gap was performed. Based on deflections measured during the pressure test, the 0 gap was most likely very near 3 mil.
43 PARTICLE ACCELERATORS↗
Axially grooved heat pipe study
A technology evaluation study on axially grooved heat pipes is presented. The state-of-the-art is reviewed and present and future requirements are identified. Analytical models, the Groove Analysis Program (GAP) and a closed form solution, were developed to facilitate parametric performance evaluations. GAP provides a numerical solution of the differential equations which govern the hydrodynamic flow. The model accounts for liquid recession, liquid/vapor shear interaction, puddle flow as well as laminar and turbulent vapor flow conditions. The closed form solution was developed to reduce computation time and complexity in parametric evaluations. It is applicable to laminar and ideal charge conditions, liquid/vapor shear interaction, and an empirical liquid flow factor which accounts for groove geometry and liquid recession effects. The validity of the closed form solution is verified by comparison with GAP predictions and measured data.
Source record↗
Effects of Double-Leakage Tip Clearance Flow on the Performance of a Compressor Stage with a Large Rotor Tip Gap
Effects of a large rotor tip gap on the performance of a one and half stage axial compressor are investigated in detail with a numerical simulation based on LES and available PIV data. The current paper studies the main flow physics, including why and how the loss generation is increased with the large rotor tip gap. The present study reveals that when the tip gap becomes large, tip clearance fluid goes over the tip clearance core vortex and enters into the next blade's tip gap, which is called double-leakage tip clearance flow. As the tip clearance flow enters into the adjacent blade's tip gap, a vortex rope with a lower pressure core is generated. This vortex rope breaks up the tip clearance core vortex of the adjacent blade, resulting in a large additional mixing. This double-leakage tip clearance flow occurs at all operating conditions, from design flow to near stall condition, with the large tip gap for the current compressor stage. The double-leakage tip clearance flow, its interaction with the tip clearance core vortex of the adjacent blade, and the resulting large mixing loss are the main flow mechanism of the large rotor tip gap in the compressor. When the tip clearance is smaller, flow near the end wall follows more closely with the main passage flow and this double-leakage tip clearance flow does not happen near the design flow condition for the current compressor stage. When the compressor with a large tip gap operates at near stall operation, a strong vortex rope is generated near the leading edge due to the double-leakage flow. Part of this vortex separates from the path of the tip clearance core vortex and travels from the suction side of the blade toward the pressure side of the blade. This vortex is generated periodically at near stall operation with a large tip gap. As the vortex travels from the suction side to the pressure side of the blade, a large fluctuation of local pressure forces blade vibration. Nonsynchronous blade vibration occurs due to this vortex as the frequency of this vortex generation is not the same as the rotor. The present investigation confirms that this vortex is a part of separated tip clearance vortex, which is caused by the double-leakage tip clearance flow.
flow↗
ECP ST Capability Assesment Report VTK-m
The ECP/VTK-m project is providing the core capabilities to perform scientific visualization on exascale architectures. The ECP/VTK-m project fills the critical feature gap of performing visualization and analysis on processors like graphics-based processors and many integrated core. The results of this project will be delivered in tools like Para View, Vislt, and Ascent as well as in stand-alone form. Moreover, these projects are depending on this ECP effort to be able to make effective use of ECP architectures.
97 MATHEMATICS AND COMPUTING↗
ECP ST Capability Assesment Report (CAR) for VTK-m (FY18)
The ECP/VTK-m project is providing the core capabilities to perform scientific visualization on Exascale architectures. The ECP/VTK-m project fills the critical feature gap of performing visualization and analysis on processors like graphics-based processors and many integrated core. The results of this project will be delivered in tools like ParaView, Vislt, and Ascent as well as in stand-alone form. Moreover, these projects are depending on this ECP effort to be able to make effective use of ECP architectures.
97 MATHEMATICS AND COMPUTING↗
ECP ST Capability Assessment Report (CAR) for VTK-m (FY19)
The ECP/VTK-m project is providing the core capabilities to perform scientific visualization on Exascale architectures. The ECP/VTK-m project fills the critical feature gap of performing visualization and analysis on processors like graphics-based processors. The results of this project will be delivered in tools like ParaView, Vislt, and Ascent as well as in stand-alone form. Moreover, these projects are depending on this ECP effort to be able to make effective use of ECP architectures.
97 MATHEMATICS AND COMPUTING↗
ECP ST Capability Assessment Report (CAR) for VTK-m (FY20)
The ECP/VTK-m project is providing the core capabilities to perform scientific visualization on Exascale architectures. The ECP/VTK-m project fills the critical feature gap of performing visualization and analysis on processors like graphics-based processors. The results of this project will be delivered in tools like ParaView, Vislt, and Ascent as well as in stand-alone form. Moreover, these projects are depending on this ECP effort to be able to make effective use of ECP architectures. One of the biggest recent changes in high-performance computing is the increasing use of accelerators. Accelerators contain processing cores that independently are inferior to a core in a typical CPU, but these cores are replicated and grouped such that their aggregate execution provides a very high computation rate at a much lower power. Current and future CPU processors also require much more explicit parallelism. Each successive version of the hardware packs more cores into each processor, and technologies like hyper threading and vector operations require even more parallel processing to leverage each core's full potential. VTK-m is a toolkit of scientific visualization algorithms for emerging processor architectures. VTK-m supports the fine-grained concurrency for data analysis and visualization algorithms required to drive extreme scale computing by providing abstract models for data and execution that can be applied to a variety of algorithms across many different processor architectures. The ECP/VTK-m project is building up the VTK-m codebase with the necessary visualization algorithm implementations that run across the varied hardware platforms to be leveraged at the Exascale. We will be working with other ECP projects, such as ALPINE, to integrate the new VTK-m code into production software to enable visualization on our HPC systems.
97 MATHEMATICS AND COMPUTING↗
On the validity of the dilute gas assumption for gap conductance calculations in nuclear fuel performance codes
Fill gas thermal conductivity’s dependence on pressure is neglected in today’s nuclear fuel performance codes. Current codes assume that gas behaves as a dilute gas, but the pressure effect is more pronounced at temperatures lower than ten times the critical temperature of each pure gas. The validity of this assumption for nuclear fuel performance is examined herein. Theories related to dilute and dense gas properties are presented, along with their validation against literature data at up to 30 MPa for selected inert gases. Underlying assumptions are clearly described for each model, and their possible impacts on gap conductance calculations are discussed. The dilute gas assumption is valid for helium because it behaves as a dilute gas. However, the assumption is not valid in most gap conductance calculations when the gap is mostly occupied with either lower conductivity gaseous fission products or an initial fill gas other than helium.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Radiological Operations Support Specialist (ROSS) Pilot Course Summary and Recommendations
In support of the Department of Homeland Security / Science and Technology Directorate’s (DHS/S&T) creation of a new position called the Radiological Operations Support Specialist (ROSS), Lawrence Livermore National Laboratory (LLNL) in Sub-task 1.1 and 1.2 has assisted in the development of the ROSS skills, knowledge, and abilities (SKAs); identified potentially relevant training; cross-mapped the training to the SKAs; and identified gaps in the training related to the SKAs, as well as their respective level of training knowledge - current versus desired. In the follow on task, Sub-task 1.3, a 5 day ROSS Pilot Training course was developed to fill the priority gaps identified in Sub-Task 1.2. Additionally, in Sub-Task 1.5, LLNL has performed a gap analysis of electronic tools, handbooks, and job-aides currently available to the ROSS and developed recommendations for additional and next generation tools to ensure the operational effectiveness of the ROSS position. This document summarizes the feedback received from the instructors and pilot course observers on what worked in the course and what could be improved as well as an assessment of the Pre- and Post-Test administered to the students.
61 RADIATION PROTECTION AND DOSIMETRY↗
Analysis on the Preliminary Gap Conductance Test with Single Primary Heat Extraction and Removal Emulator
Microreactor is a type of nuclear reactor that is intended to produce thermal energy from the micro and integrated design. Among various microreactor roadmaps, microreactor with heat pipes is one of the promising designs that under active development. At Idaho National Laboratory (INL) and supported by the Department of Energy (DOE) Microreactor Program (MRP), a Single Primary Heat Extraction and Removal Emulator (SPHERE) was developed. The main purpose of SPHRE is to understand thermal performance of heat pipe in the conjunction of heat source without using nuclear material. The heat pipe used in the SPHERE has sodium as a working fluid, with Argon gas in the vapor region, thus this heat pipe is variable conductance heat pipe (VCHP). The volume of non-condensable gas changes with power and elapsed time, so the area covered by non-condensable gas changes. This gives an effect that passively controls the cooling capability of condenser section. This preliminary experiment was intended to perform a gap conductance experiment that reveals heat transfer characteristics of gas at the gap around the heat pipe. However, there are not many experimental data that deals with heat transfer of the gas at the gap around heat pipe. In this research, the preliminary experimental result regarding to the heat pipe performance with different composition of gas at the gap, level of power is presented. The experimental data will be used for the validation study of SOCKEYE as a future plan.
42 ENGINEERING↗
A Review of State-of-the-Art Separator Materials for Advanced Lithium-Based Batteries for Future Aerospace Missions
As NASA embarks on a renewed human presence in space, safe, human-rated, electrical energy storage and power generation technologies, which will be capable of demonstrating reliable performance in a variety of unique mission environments, will be required. To address the future performance and safety requirements for the energy storage technologies that will enhance and enable future NASA Constellation Program elements and other future aerospace missions, advanced rechargeable, lithium-ion battery technology development is being pursued with an emphasis on addressing performance technology gaps between state-of-the-art capabilities and critical future mission requirements. The material attributes and related performance of a lithium-ion cell's internal separator component are critical for achieving overall optimal performance, safety and reliability. This review provides an overview of the general types, material properties and the performance and safety characteristics of current separator materials employed in lithium-ion batteries, such as those materials that are being assessed and developed for future aerospace missions.
Bladwin, Richard S.↗
The Building Business Network (B-Biz): Addressing Gaps in the High-Performance Building Technology Market, Especially for Underserved Customers
Increased market intelligence and business model innovation is needed to build contractor confidence in high-performance building technologies in order to increase the speed and scale of adoption to meet the U.S. Department of Energy's building stock decarbonization goals. Although there have been important innovations in energy efficiency, affordability, and decarbonization of building technologies, consumers are not purchasing these technologies at the necessary speed and scale partially due to a gap in institutional understanding around barriers contractors face in providing and servicing these technologies. Small businesses in this market must mitigate risk around high-performance building technologies, limiting their opportunities in the market and impacting the rate of adoption. The Building Business Network (B-Biz) aims to provide high-performance building technology solutions to underserved customers by collaborating with local small businesses that provide and service high-performance building technologies in communities with the lowest rates of adoption. This research explores the current market, the importance of business models, and the opportunity to utilize small businesses to address market gaps in underserved communities.
B-Biz↗
Tunnel and field effect carrier ballistics
Methods and apparatus for interacting carriers with a structure of matter employ an electrode for emitting said carriers at a distance from a surface of that structure, and cause such carriers to travel along ballistic trajectories inside that structure by providing along the mentioned distance a gap for performance of a process selected from the group of carrier tunneling and field emission and injecting carriers emitted by the mentioned electrode and that process ballistically into the structure through the gap and the mentioned surface. The carriers are collected or analyzed after their travel along ballistic trajectories in the structure of matter. Pertinent information on the inside of the structure is obtained by conducting inside that structure what conventionally would have been considered external ballistics, while performing the carrier-propelling internal ballistics conversely outside that structure.
Kaiser, William J.↗
Performance Evaluation of a Single-Phase Grid-Forming Inverter Through Hardware Experiments: Preprint
Existing state-of-the-art of single-phase grid-forming (GFM) inverter are primarily focused on electromagnetic transient simulation, and there are very few works performing hardware test, and there is no clear understanding how the single-phase GFM inverter should behave from a hardware perspective. Therefore, this paper addresses the gap by performing hardware experiment to evaluate the performance of a single-phase GFM hardware inverter. We enrich the existing GFM testing protocols by investigating transient performance of GFM inverters under different grid dynamic events, and quantifiable performance metrics are made to have a common understanding of expected performance of single-phase GFM inverters. A commercial single-phase GFM inverter is used to verify the test protocols and understand the inverter's performance and functionalities.
dynamic events↗