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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 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

TPCPF: Three-Phase Continuation Power Flow Tool for Voltage Stability Assessment of Distribution Networks With Distributed Energy Resources

This article presents a three-phase unbalanced continuation power flow algorithm for voltage stability assessment of distribution systems with high penetration of distributed energy resources (DERs). Analyzing distribution system voltage stability with DER will allow high penetration of renewable energy necessary for the sustainability goals. The developed algorithm can analyze voltage stability for both the meshed and radial systems and the balanced and unbalanced three-phase distribution systems. The developed tool allows the voltage stability analysis to facilitate the planning, operation, control, and distribution system management. The impact of DER on the voltage stability of several test cases has been analyzed considering constant power (P Q) and regulated-voltage (P V ) modes of operation for DER units. Moreover, different voltage stability case studies are presented to demonstrate the impact of unbalance, load increment, and network topology on the maximum loading capacity. Finally, results using the IEEE 13-node feeder, the 18-bus balanced shipboard system, the 13-node CIGRE benchmark system, and the 136-bus redial distribution feeder demonstrate that the developed continuation power flow tool can efficiently perform voltage stability analysis for active distribution systems.

42 ENGINEERING↗
DOE OSTI2022

tell: a Python package to model future total electricity loads in the United States

The purpose of the Total ELectricity Load (tell) model is to generate 21st century profiles of hourly electricity load (demand) across the Conterminous United States (CONUS). tell loads reflect the impact of climate and socioeconomic change at a spatial and temporal resolution adequate for input to an electricity grid operations model. tell uses machine learning to develop profiles that are driven by projections of climate/meteorology and population. tell also harmonizes its results with United States (U.S.) state-level, annual projections from a national- to global-scale energy-economy model. This model accounts for a wide range of other factors affecting electricity demand, including technology change in the building sector, energy prices, and demand elasticities, which stems from model coupling with the U.S. version of the Global Change Analysis Model (GCAM-USA). tell was developed as part of the Integrated Multisector Multiscale Modeling (IM3) project. IM3 explores the vulnerability and resilience of interacting energy, water, land, and urban systems in response to compound stressors, such as climate trends, extreme events, population, urbanization, energy system transitions, and technology change

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Empirical Validation of Multi-Zone HVAC System Model: Evaluation of Existing Infiltration Models used in Building Energy Simulation

Infiltration can have a significant impact on building loads. Studies have shown that infiltration can account for 15-40% of annual space conditioning needs in commercial buildings (Emmerich et al. 2019; Younes et al. 2012). The driving force of infiltration is the pressure difference across the building envelope caused by wind, the stack effect (known as buoyancy effect), and the operation of ventilation equipment. Wind pressure is governed by wind direction, speed, building shape, and other structures around the building. The stack effect is a function of the building height and air density differences of ambient air (Han, 2015). The effect of wind is dominant in low-rise residential buildings, and the stack effect is dominant in highrise buildings (ASHRAE 2017). In building energy simulation programs (e.g., EnergyPlus), various empirical infiltration models (e.g., the effective leakage area model, the flow coefficient model) are available to simulate infiltration rates. To help users in selecting a proper infiltration model for modeling of the two-story Flexible Research Platform (FRP), the team evaluates the existing infiltration models in EnergyPlus based on field measurements from the FRP. The blower door and tracer gas decay tests were performed in the FRP. The blower door test result was used to estimate input parameters required in the infiltration models. The actual infiltration rates were estimated with the tracer gas decay test results.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Aeroacoustic Assessment of Wind Plant Controls

The Aeroacoustic Assessment project aims to quantify changes in aeroacoustic noise generation by a utility scale wind turbine operating under imposed yaw offsets common for wake steering and wind plant control strategies. Active plant control utilizing wake deflection control strategies have been shown experimentally and computationally to reliably produce 1-2% of additional annual energy production (AEP) without significant changes in turbine structural loads, the potential impact on aeroacoustic emissions has yet to be quantified or completely understood. Yawed operation of a wind turbine changes the three-dimensional aerodynamic interaction between the rotor blades and the incoming atmospheric flow, leading to changes in noise generation. This work quantifies the extent to which active control induces additional aeroacoustic emissions from additional separation and other flow interaction dynamic effects. Given public concerns about wind turbine noise and the need for observational data required for regulators to establish noise restrictions, we must understand potential acoustic emissions resulting from active control prior to commercial deployment and the development of practical noise reduction methods and technologies. The work outlined in this report details the new aeroacoustic measurement capability developed at NREL and its application to making full-field observations of noise from a utility-scale wind turbine. Preliminary noise modeling with the aeroacoustics module in OpenFAST helped to establish the design of the experiment, specifically targeting the noise observed at observers distributed around the DOE-owned GE 1.5 MW wind turbine. Low-frequency and infrasound measurement capability implemented in this project establish an operational baseline for the wind turbine, setting the stage for future control, rotor blade, and turbine design research.

17 WIND ENERGY↗
DOE OSTI2024

Datasets for Widespread Residential Space Heating Electrification in Texas

In this experiment, we explore long term patterns in electricity demand driven by the dual effects of full electrification of space heating in Texas (by adoption of electric heat pumps), and climate change. We use a predictive model of electricity demand, climate projections, and an open source nodal power system (DC Optimal Power Flow) model of the Electric Reliability Council of Texas (ERCOT) system. Heat pumps are a more energy efficient way of providing space heating and cooling in homes. We attempt to exhaustively investigate the impacts of full residential space heating electrification by adoption of heat pumps for the segment of Texas households that currently rely on fossil fuels (about 40%), while simultaneously incorporating climate change meteorological variables. We explore a range of scenarios of heat pump efficiency and climate uncertainty over a long period of future years (2020-2099). In total, the simulation experiment generates 1,280 simulation years of hourly data. We report and analyze results in form of impacts on residential load, total load, peak load, seasonality of peaking, and reliability measured by occurrence and frequency of loss of load events. While the experiment is for ERCOT, the insights and approach can be applied to other regions. The results from the analysis can inform system planners on a range of potential capacity requirements/ reliability implications and/or risks of full space heating electrification via the adoption of electric heat pumps, given the uncertainty in the scenarios/ climate futures. The dataset includes model output for residential, non residential and total load, and the results from the GO ERCOT model runs for 4 RCP Scenarios (RCP 4.5 Cooler, RCP 4.5 Hotter, RCP 8.5 Cooler, RCP 8.5 Hotter), 4 Heating electrification Scenarios (Base , Standard Efficiency HP, High Efficiency HP, Ultra-High Efficiency HP) over 80 years (2020-2099). The metrological variables at BA scale were weighted weighted using population projections consistent with the SSP3 scenario.

Climate Change↗
NASA NTRS1972

Use of thin plastic films at cryogenic temperatures

Commercially available plastic film materials that remain flexible at cryogenic temperatures and resist failures caused by folds and wrinkles created during expulsion were investigated for use in expulsion bladders for liquefied gases. Compatible adhesive systems, fabrication techniques, and results of impact and dynamic loading tests are summarized.

Lark, R. F.↗
NASA NTRS1971

An inventory of aeronautical ground research facilities. Volume 3: Structural

An inventory of test facilities for conducting acceleration, environmental, impact, structural shock, load, heat, vibration, and noise tests is presented. The facility is identified with a description of the equipment, the testing capabilities, and cost of operation. Performance data for the facility are presented in charts and tables.

Pirrello, C. J.↗
NASA NTRS1972

Agricultural and urban pollution

The degradation produced by the introduction of agricultural and urban wastes into estuarine systems, with emphasis on the Chesapeake Bay area, is discussed. The subjects presented are: (1) effects of sediment loading and (2) organic and nutrient loading problems. The impact of high turbidity on the biological life of the bay is analyzed. The sources of nutrients which produce over-enrichment of the waters and the subsequent production of phytoplankton are examined.

Brehmer, M. L.↗
NASA NTRS1974

Advanced fiber-composite hybrids--A new structural material

Introduction of metal foil as part of matrix and fiber composite, or ""sandwich'', improves strength and stiffness for multidirectional loading, improves resistance to cyclic loading, and improves impact and erosion resistance of resultant fiber-composite hybrid structure.

Chamis, C. C.↗
NASA NTRS1974

High temperature polyimide foams for shuttle upper surface thermal insulation

Polyimide foams developed by Monsanto Company were examined for use as upper surface space shuttle thermal insulation. It was found that postcured polyimide foams having a density of 64 kg/cu m (4 lb/cu ft) had acceptable physical properties up to and exceeding 700 K (800 F). Physical tests included cyclic heating and cooling in vacuum, weight and dimensional stability, mechanical strength and impact resistance, acoustic loading and thermal conductivity. Molding and newly developed postcuring procedures were defined.

Ball, G. L., III↗
NASA NTRS1987

Energy-Absorbing Passenger Seat for Aircraft

Development of energy-absorbing passenger seat, designed to minimize injury in commercial-aircraft crash, part of joint FAA/NASA controlledimpact flight test of transport-category commercial aircraft. Modified seat mechanism collapses under heavy load to absorb impact energy and thereby protect passenger. Results of simulation tests indicate probability of passenger survival high. Proposed seat mechanism mitigates passenger injuries by reducing impact forces in crash.

Eichelberger, C. P.↗
NASA NTRS1987

Access flight hardware design and development

Several items were found to be of immense value in the design and development of the Assembly Concept for Construction of Erectable Space Structures (ACCESS) hardware. The early availability of mock-up and engineering test hardware helped to develop the concept and prove the feasibility of the experiment. The extensive neutral buoyancy testing was invaluable in developing the procedures and timelines, proving that the hardware functioned as intended, and effectively trained the astronauts. The early involvement of the crew systems/astronaut personnel was extremely beneficial in shaping the design to meet the EVA compatibility requirements. Also, the early definition of coupled loads and on-orbit dynamic responses can not be overemphasized due to the relative uncertainty in the magnitude of these loads and their impact on the design.

Rogers, John F.↗
NASA NTRS1988

Docking system for spacecraft

A mechanism is disclosed for the docking of a spacecraft to a space station where a connection for transfer of personnel and equipment is desired. The invention comprises an active docking structure on a spacecraft and a passive docking structure on the station. The passive structure includes a docking ring mounted on a tunnel structure fixed to the space station. The active structure includes a docking ring carried by an actuator-attenuator devices, each attached at one end to the ring and at its other end in the spacecraft payload bay. The devices respond to command signals for moving the docking ring between a stowed position in the spacecraft to a deployed position suitable for engagement with the docking ring. The devices comprise means responsive to signals of sensed loadings to absorb impact energy and retraction means for drawing the coupled spacecraft and station into final docked configuration and moving the tunnel structure to a berthed position in the spacecraft. Latches couple the spacecraft and space station upon contact of the docking rings and latches establish a structural tie between the spacecraft when retracted.

Kahn, Jon B.↗
NASA NTRS1989

A hybrid procedure for dynamic characterization of ceramics at elevated temperature

A hybrid experimental-numerical procedure to characterize the dynamic fracture response of ceramics and ceramic composites at temperatures in excess of 1400 C is described. This hybrid methodology was developed to characterize dynamic fracture responses and to study the effect of temperature on dynamic fracture responses of ceramics and ceramic matrix composites. The hybrid methodology was used to determine the dynamic stress intensity factors (SIF) associated with a running crack in a three-point bend specimen at elevated temperature. This procedure was utilized to determine the dynamic SIF versus crack velocity relations of alumina, TiB2-particulate/SiC-matrix composite, and SiC-whisker/Al2O3-matrix composite. Minor differences in the dynamic SIF versus crack velocity relations at room and elevated temperature were seen, and significant differences under impact and static loadings were observed in the dynamic SIF versus crack velocity relations.

Yang, K. H.↗
NASA NTRS1991

Response of composite materials to low velocity impact

Orthotropic and quasiisotropic laminates clamped at the edges were impacted by an instrumented falling weight. Five matrix materials, comprising a baseline epoxy, two toughened thermosets, and amorphous and crystalline thermoplastics were studied. For each material, the projected damage area and residual compression strengths and strains were determined as a function of impact energy. Principal conclusions are: (1) incipient damage associated with a prominent load drop during the impact test seems to be decisive for residual properties; (2) subtle rate effects are present with some materials; and (3) results from the small scale tests parallel those in standard tests and may be adequate for screening purposes.

Srinivasan, K.↗
NASA NTRS1991

Response of composite materials to low velocity impact

Orthotropic and quasi-isotropic laminates clamped at the edges were impacted by an instrumented falling weight. Five matrix materials, comprising a baseline epoxy, two toughened thermosets, and amorphous and crystalline thermoplastics were studied. For each material, the projected damage area and residual compression strengths and strains were determined as a function of impact energy. Principal conclusions are: (1) incipient damage associated with a prominent load drop during the impact test seems to be decisive for residual properties; (2) subtle rate effects are present with some materials; and (3) results from the small scale tests parallel those in standard tests and may be adequate for screening purposes.

Srinivasan, K.↗
NASA NTRS1995

Planetary and deep space requirements for photovoltaic solar arrays

In the past 25 years, the majority of interplanetary spacecraft have been powered by nuclear sources. However, as the emphasis on smaller, low cost missions gains momentum, the majority of missions now being planned will use photovoltaic solar arrays. This will present challenges to the solar array builders, inasmuch as planetary requirements usually differ from earth orbital requirements. In addition, these requirements often differ greatly, depending on the specific mission; for example, inner planets vs. outer planets, orbiters vs. flybys, spacecraft vs. landers, and so on. Also, the likelihood of electric propulsion missions will influence the requirements placed on solar array developers. The paper will discuss representative requirements for a range of planetary missions now in the planning stages. Insofar as inner planets are concerned, a Mercury orbiter is being studied with many special requirements. Solar arrays would be exposed to high temperatures and a potentially high radiation environment, and will need to be increasingly pointed off sun as the vehicle approaches Mercury. Identification and development of cell materials and arrays at high incidence angles will be critical to the design. Missions to the outer solar system that have been studied include a Galilean orbiter and a flight to the Kuiper belt. While onboard power requirements would be small (as low as 10 watts), the solar intensity will require relatively large array areas. As a result, such missions will demand extremely compact packaging and low mass structures to conform to launch vehicle constraints. In turn, the large are, low mass designs will impact allowable spacecraft loads. Inflatable array structures, with and without concentration, and multiband gap cells will be considered if available. In general, the highest efficiency cell technologies operable under low intensity, low temperature conditions are needed. Solar arrays will power missions requiring as little as approximately 100 watts, up to several kilowatts (at Earth) in the case of solar electric propulsion missions. Thus, mass and stowage volume minimization will be required over a range of array sizes. Concentrator designs, inflatable structures, and the combination of solar arrays with the telecommunications system have been proposed. Performance, launch vehicle constraints, an cost will be the principal parameters in the design trade space. Other special applications will also be discussed, including requirements relating to planetary landers and probes. In those cases, issues relating to shock loads on landing, operability in (possibly dusty) atmospheres, and extreme temperature cycles must be considered, in addition to performance, stowed volume, and costs.

Bankston, C. P.↗
NASA NTRS1996

Analysis of the access patterns at GSFC distributed active archive center

The Goddard Space Flight Center (GSFC) Distributed Active Archive Center (DAAC) has been operational for more than two years. Its mission is to support existing and pre Earth Observing System (EOS) Earth science datasets, facilitate the scientific research, and test Earth Observing System Data and Information System (EOSDIS) concepts. Over 550,000 files and documents have been archived, and more than six Terabytes have been distributed to the scientific community. Information about user request and file access patterns, and their impact on system loading, is needed to optimize current operations and to plan for future archives. To facilitate the management of daily activities, the GSFC DAAC has developed a data base system to track correspondence, requests, ingestion and distribution. In addition, several log files which record transactions on Unitree are maintained and periodically examined. This study identifies some of the users' requests and file access patterns at the GSFC DAAC during 1995. The analysis is limited to the subset of orders for which the data files are under the control of the Hierarchical Storage Management (HSM) Unitree. The results show that most of the data volume ordered was for two data products. The volume was also mostly made up of level 3 and 4 data and most of the volume was distributed on 8 mm and 4 mm tapes. In addition, most of the volume ordered was for deliveries in North America although there was a significant world-wide use. There was a wide range of request sizes in terms of volume and number of files ordered. On an average 78.6 files were ordered per request. Using the data managed by Unitree, several caching algorithms have been evaluated for both hit rate and the overhead ('cost') associated with the movement of data from near-line devices to disks. The algorithm called LRU/2 bin was found to be the best for this workload, but the STbin algorithm also worked well.

Johnson, Theodore↗