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At least 1,603 records · Page 89
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Impacts of Using Distributed Energy Resources to Reduce Peak Loads in Vermont

To help the United States develop a modern electricity grid that provides reliable power from multiple resources as well as resiliency under extreme conditions, the U.S. Department of Energy (DOE) is leading the Grid Modernization Initiative (GMI) to help shape the future of the nation's grid. Under the GMI, DOE funded the Vermont Regional Initiative project to provide the technical support and analysis to utilities that need to mitigate possible impacts of increasing renewable generation required by statewide goals. Advanced control of distributed energy resources (DER) can both support higher penetrations of renewable energy by balancing controllable loads to wind and photovoltaic (PV) solar generation and reduce peak demand by shedding noncritical loads. This work focuses on the latter. This document reports on an experiment that evaluated and quantified the potential benefits and impacts of reducing the peak load through demand response (DR) using centrally controllable electric water heaters (EWHs) and batteries on two Green Mountain Power (GMP) feeders. The experiment simulated various hypothetical scenarios that varied the number of controllable EWHs, the amount of distributed PV systems, and the number of distributed residential batteries. The control schemes were designed with several objectives. For the first objective, the primary simulations focused on reducing the load during the independent system operator (ISO) peak when capacity charges were the primary concern. The second objective was to mitigate DR rebound to avoid new peak loads and high ramp rates. The final objective was to minimize customers' discomfort, which is defined by the lack of hot water when it is needed. We performed the simulations using the National Renewable Energy Laboratory's (NREL's) Integrated Energy System Model (IESM) because it can simulate both electric power distribution feeder and appliance end use performance and it includes the ability to simulate multiple control strategies.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1974

Stability and control characteristics for the inner mold line configuration of the space shuttle orbiter (OA110)

Experimental aerodynamic investigations were conducted on a sting mounted 0.0405-scale representation of the -140A/B inner mold line (IML) space shuttle orbiter in 7.75 x 11 foot low speed wind tunnel, during the time period from 18 March 1974 to 20 March 1974. The primary test objectives were to establish basic longitudinal and lateral-directional stability and control characteristics for the IML orbiter. Additional configurations investigated were sealed elevon hingeline gaps, sealed rudder split line and hingeline gaps, larger radius leading edge on the vertical tail, and sealed speedbrake base. Aerodynamic force and moment data for the orbiter were measured in the body-axis system by an internally mounted, six-component strain gage balance. The model was sting mounted with the center of rotation located at approximately the wing trailing edge. The nominal angle of attack range was from -4 to +30 degrees. Yaw polars were recorded over a nominal yaw angle range from -14 to +14 degrees at constant angles of attack of 0, + or - 5, 10, 15 and 20 degrees.

Hughes, T.↗
DOE OSTI2016

Regulatory Compliance of H Retention Basin Using Rhombo Balls - 16151

Elevated pH conditions in the Savannah River Site 281-8H Retention Basin will have to be resolved prior to the issuance of a new National Pollutant Discharge Elimination System permit. The 281-8H retention basin collects rain water runoff, cooling tower blow downs and steam condensate from H Area Tank Farm operation processes. The basin discharges to a South Carolina Department of Health and Environmental Control National Pollutant Discharge Elimination System permitted out-fall, H-12. The permit requires the out-fall to meet certain discharge requirements. The National Pollutant Discharge Elimination System permit requires the pH to be within the range 4.8 to 8.5. The 281-8H Retention Basin has a steady history of elevated pH levels, above 8.5, especially during the warmer months of the year, normally March through October. The rise in pH has been attributed to the exponential growth of algae which occurs during the warm months of the year. The increased algae colonies undergo photosynthesis which depletes the CO{sub 2} in the basin water and subsequently raises the pH level. The current permit allows simultaneous discharge of low pH well water, pH between 4.6 and 5.0, and the 281-8H Retention Basin water which provides blending to achieve regulatory compliance. The regulatory agency indicated in 2010 that adding well water to achieve compliance of pH limits will not be allowed when the new permit is issued in the future. Therefore, a solution to the high pH had to be identified and implemented in order to ensure regulatory compliance. A system engineering evaluation was conducted to determine the best solution to the large algae colonies and high pH levels. The evaluation identified options in four primary categories as well as some combination of those categories to control algae growth and to ultimately increase the amount of CO{sub 2} in the basin. Eleven evaluation criteria were developed for the various options, and a percentage (out of 100%) was assigned to related groups of criteria. Twenty-six options were evaluated during this process. The highest ranking options determined from the evaluation were the 12-sided Rhombo ball floating cover, biological digester and a combination of the digester and the floating cover. Option 3, a combination of the top two choices, was chosen as the best approach. The Rhombo cover along with the initial shock application of a biological digester has worked to eliminate algae growth and lower the pH level. The Rhombos have significantly lowered the basin pH level from greater than 9 to less than 7, which is within the regulatory compliance pH requirements of 4.8 to 8.5. The system engineering evaluation and subsequent solution chosen are useful in many venues. The application of the 12 sided Rhombo ball's unique ability to nestle together no matter which way they turn is advantageous to applications/problems that need to block 99.99% sunlight from a body of water. The 281-8H Retention Basin required nine 18 wheeler truckloads with trailers that were 16.2 m (53 Ft) long and filled with Rhombo balls. The basin required a total of approximately 700,000 Rhombo balls to be fully covered. They are easy to install and handle. The Rhombo balls have wind resistance up to 120 Km/hr (75 MPH) and have a life expectancy of 25 years. This application can be used to control plant and algae growth and is effective in evaporation reduction at 99%. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Investigating controls on sea ice algal production using E3SMv1.1-BGC

We present the analysis of global sympagic primary production (PP) from 300 years of pre-industrial and historical simulations of the E3SMv1.1-BGC model. The model includes a novel, eight-element sea ice biogeochemical component, MPAS-Seaice zbgc, which is resolved in three spatial dimensions and uses a vertical transport scheme based on internal brine dynamics. Modeled ice algal chlorophyll-a concentrations and column-integrated values are broadly consistent with observations, though chl-a profile fractions indicate that upper ice communities of the Southern Ocean are underestimated. Simulations of polar integrated sea ice PP support the lower bound in published estimates for both polar regions with mean Arctic values of 7.5 and 15.5 TgC/a in the Southern Ocean. However, comparisons of the polar climate state with observations, using a maximal bound for ice algal growth rates, suggest that the Arctic lower bound is a significant underestimation driven by biases in ocean surface nitrate, and that correction of these biases supports as much as 60.7 TgC/a of net Arctic PP. Simulated Southern Ocean sympagic PP is predominantly light-limited, and regional patterns, particularly in the coastal high production band, are found to be negatively correlated with snow thickness.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Quality Control of and Analysis Enabling Use of MARCUS and MICRE data for Scientific Applications

The primary objective of this project was to provide a preliminary investigation of data collected during the MARCUS/MICRE field experiments and to produce products and analysis for the scientific community that will enable future scientific investigations and hypothesis testing. Further, the goal was to assist those in the scientific community to understand the strengths and caveats of the MARCUS/MICRE data so that members of the scientific community could use the data in their publications.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1979

A tactual display aid for primary flight training

A means of flight instruction is discussed. In addition to verbal assistance, control feedback was continously presented via a nonvisual means utilizing touch. A kinesthetic-tactile (KT) display was used as a readout and tracking device for a computer generated signal of desired angle of attack during the approach and landing. Airspeed and glide path information was presented via KT or visual heads up display techniques. Performance with the heads up display of pitch information was shown to be significantly better than performance with the KT pitch display. Testing without the displays showed that novice pilots who had received tactile pitch error information performed both pitch and throttle control tasks significantly better than those who had received the same information from the visual heads up display of pitch during the test series of approaches to landing.

Gilson, R. D.↗
NASA NTRS2007

The Influence of Sea Ice on Primary Production in the Southern Ocean: A Satellite Perspective

Sea ice in the Southern Ocean is a major controlling factor on phytoplankton productivity and growth, but the relationship is modified by regional differences in atmospheric and oceanographic conditions. We used the phytoplankton biomass (binned at 7-day intervals), PAR and cloud cover data from SeaWiFS, ice concentrations data from SSM/I and AMSR-E, and sea-surface temperature data from AVHRR, in combination with a vertically integrated model to estimate primary productivity throughout the Southern Ocean (south of 60"s). We also selected six areas within the Southern Ocean and analyzed the variability of the primary productivity and trends through time, as well as the relationship of sea ice to productivity. We found substantial interannual variability in productivity from 1997 - 2005 in all regions of the Southern Ocean, and this variability appeared to be driven in large part by ice dynamics. The most productive regions of Antarctic waters were the continental shelves, which showed the earliest growth, the maximum biomass, and the greatest areal specific productivity. In contrast, no large, sustained blooms occurred in waters of greater depth (> 1,000 m). We suggest that this is due to the slightly greater mixed layer depths found in waters off the continental shelf, and that the interactive effects of iron and irradiance (that is, increased iron requirements in low irradiance environments) result in the limitation of phytoplankton biomass over large regions of the Southern Ocean.

Smith, Walker O., Jr.↗
NASA NTRS2000

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

High Cycle Fatigue (HCF) induced failures in aircraft gas-turbine engines is a pervasive problem affecting a wide range of components and materials. HCF is currently the primary cause of component failures in gas turbine aircraft engines. Turbine blades in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys. Single-crystal Nickel-base superalloys were developed to provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys previously used in the production of turbine blades and vanes. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493 and PWA 1484. These alloys play an important role in commercial, military and space propulsion systems. PWA1493, identical to PWA1480, but with tighter chemical constituent control, is used in the NASA SSME (Space Shuttle Main Engine) alternate turbopump, a liquid hydrogen fueled rocket engine. Objectives for this paper are motivated by the need for developing failure criteria and fatigue life evaluation procedures for high temperature single crystal components, using available fatigue data and finite element modeling of turbine blades. Using the FE (finite element) stress analysis results and the fatigue life relations developed, the effect of variation of primary and secondary crystal orientations on life is determined, at critical blade locations. The most advantageous crystal orientation for a given blade design is determined. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to optimize blade design by increasing its resistance to fatigue crack growth without adding additional weight or cost.

Arakere, Nagaraj K.↗
NASA NTRS1983

AFTI/F-16 flight test results and lessons

The advanced fighter technology integration (AFTI) F-16 aircraft is a highly complex digital flight control system integrated with advanced avionics and cockpit. The use of dissimilar backup modes if the primary system fails requires the designer to trade off system simplicity and capability. The tradeoff is evident in the AFTI/F-16 aircraft with its limited stability and fly by wire digital flight control systems when a generic software failure occurs the backup or normal mode must provide equivalent envelop protection during the transition to degraded flight control. The complexity of systems like the AFTI/F-16 system defines a second design issue, which is divided into two segments: (1) the effect on testing, (2) and the pilot's ability to act correctly in the limited time available for cockpit decisions. The large matrix of states possible with the AFTI/F-16 flight control system illustrates the difficulty of both testing the system and choosing real time pilot actions. The third generic issue is the possible reductions in the user's reliability expectations where false single channel information can be displayed at the pilot vehicle interface while the redundant set remains functional.

Ishmael, S. D.↗
NASA NTRS1989

The Circumstellar Imaging Telescope image motion compensation system - Ultra-precise control on the Space Station platform

The Circumstellar Imaging Telescope (CIT) is a 1.9 m visible wavelength Cassegrain instrument whose primary mission is to locate extra-solar planets by direct imaging. The current reference concept calls for it to be deployed as a Space Station attached payload some time in the late 1990s. Mission and signal processing demands impose the following attitude control requirements: pointing accuracy - 250 nrad RMS, pointing stability - 50 nrad RMS over 30 minutes, roll accuracy - 1 mrad RMS, roll stability 1 mrad RMS over 30 minutes. This paper reports on the results of a recent design study in which it was determined that these requirements can be met on the Space Station by a three tiered control system consisting of a two degree of freedom mechanical gimbal for course pointing, a magnetically suspended roll bearing for roll accommodation, translational isolation and intermediate pointing control, and articulation of the secondary mirror for fine pointing.

Sevaston, G. E.↗
NASA NTRS1994

F/A-18 forebody vortex control. Volume 2: Rotary-balance tests

A rotary-balance wind tunnel test was conducted on a six percent model of the F/A-18 at the NASA Ames 7 X 10-Foot Low Speed Wind Tunnel. The data reduction was specially written for the test in National Instruments' LabVIEW. The data acquisition, reduction and analysis was performed with a Macintosh computer. The primary objective of the test was to evaluate the effectiveness of several forebody vortex control configurations in a rotary flow field. The devices that were found to be the most effective during the static tests (Volume 1) were investigated and included both mechanical and pneumatic configurations. The mechanical systems evaluated were small, single and dual, rotating nose tip strakes and a vertical nose strake. The jet blowing configuration used nozzles canted inboard 60 degrees. A two segment tangential slot was also evaluated. The different techniques were evaluated at angles of attack of 30 degrees, 45 degrees, 51 degrees, and 60 degrees. Sideslip and Reynolds number were varied for some of the configurations. All of the techniques proved to be effective in the rotating flow field. The vertical nose strake had the largest 'envelope' of effectiveness. Forebody vortex control provides large, robust yawing moments at medium to high angles of attack, even during combat maneuvers such as loaded roll.

Kramer, Brian R.↗
NASA NTRS2011

Composite Thermal Switch

Lithium primary and lithium ion secondary batteries provide high specific energy and energy density. The use of these batteries also helps to reduce launch weight. Both primary and secondary cells can be packaged as high-rate cells, which can present a threat to crew and equipment in the event of external or internal short circuits. Overheating of the cell interior from high current flows induced by short circuits can result in exothermic reactions in lithium primary cells and fully charged lithium ion secondary cells. Venting of the cell case, ejection of cell components, and fire have been reported in both types of cells, resulting from abuse, cell imperfections, or faulty electronic control design. A switch has been developed that consists of a thin layer of composite material made from nanoscale particles of nickel and Teflon that conducts electrons at room temperature and switches to an insulator at an elevated temperature, thus interrupting current flow to prevent thermal runaway caused by internal short circuits. The material is placed within the cell, as a thin layer incorporated within the anode and/or the cathode, to control excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect. The safety of high-rate cells is thus improved, preventing serious injury to personnel and sensitive equipment located near the battery. The use of recently available nanoscale particles of nickel and Teflon permits an improved, homogeneous material with the potential to be fine-tuned to a unique switch temperature, sufficiently below the onset of a catastrophic chemical reaction. The smaller particles also permit the formation of a thinner control film layer (<50 m), which can be incorporated into commercial high-rate lithium primary and secondary cells. The innovation permits incorporation in current lithium and lithium-ion cell designs with a minimal impact on cell weight and volume. The composite thermal switch (CTS(TradeMark)) coating can be incorporated in either the anode or cathode or both. The coating can be applied in a variety of different processes that permits incorporation in the cell and electrode manufacturing processes. The CTS responds quickly and halts current flow in the hottest parts of the cell first. The coating can be applied to metal foil and supplied as a cell component onto which the active electrode materials are coated.

McDonald, Robert↗
DOE OSTI2021

Response of Stream Metabolism to Coarse Woody Debris Additions Along a Catchment Disturbance Gradient

We evaluated the ecological effectiveness of an in-stream restoration project involving coarse woody debris (CWD) additions to streams along an upland soil and vegetation disturbance gradient at the Fort Benning Military Installation near Columbus, GA. We examined short-term (immediate effectiveness) and longer-term (sustainability) responses to CWD additions by measuring ecosystem metabolism rates in 8 streams quarterly over a 6-year period, including 3 years before (2001–2003) and 3 years after (2004–2006) CWD additions that were made to half of the streams. Ecosystem respiration (ER) rates in most CWD addition streams increased relative to control streams from spring 2004 through autumn 2005, suggesting heterotrophic bacteria were the initial responders to CWD additions. Gross primary production (GPP) rates remained low (typically < 0.3 g O 2 m -2 d -1 ) but increased in some CWD addition streams relative to control streams in spring 2004 and 2005. The magnitude of ER increases in CWD addition streams during the first two years post-addition increased with catchment disturbance intensity, indicating that more heavily disturbed streams responded most strongly to restorations—an important consideration when targeting future restoration locations. Because restorations did not address actual upland disturbance, continued high erosion rates resulted in 32–77% of the added CWD being buried by year two and a corresponding return of GPP and ER rates to pre-CWD addition levels by year three. If restoration projects do not adequately address the source of catchment disturbances, CWD additions will provide only short-term increases in streambed structure and stability, hydrodynamic complexity, and nutrient and organic matter processing and retention.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Historical Trends in PM 2.5 -Related Premature Mortality during 1990$-$2010 across the Northern Hemisphere

Air quality across the northern hemisphere over the past two decades has witnessed dramatic changes, with continuous improvement in developed countries in North America and Europe, but a contrasting sharp deterioration in developing regions of Asia. Objective: This study investigates the historical trend in the long-term exposure to PM 2.5 and PM 2.5 -related premature mortality (PM 2.5 -mortality) and its response to changes in emission that occurred during 1990-2010 across the northern hemisphere. Implications for future trends in human exposure to air pollution in both developed and developing regions of the world are discussed. Methods: We employed the integrated exposure-response model developed by Health Effects Institute to estimate the PM 2.5 -mortality. The 1990-2010 annual-average PM 2.5 concentrations were obtained from the simulations using WRF-CMAQ model. Emission mitigation efficiencies of SO 2 , NO x , NH 3 and primary PM are estimated from the PM 2.5 -mortality responses to the emission variations. Results: Estimated PM 2.5 -mortalities in East Asia and South Asia increased by 21% and 85% respectively, from 866,000 and 578,000 in 1990, to 1,048,000 and 1,068,000 in 2010. PM2.5-mortalities in developed regions, i.e., Europe and high-income North America decreased substantially by 67% and 58% respectively. Conclusions: Over the past two decades, correlations between population and PM 2.5 have become weaker in Europe and North America due to air pollution controls but stronger in East Asia due to deteriorating air quality. Mitigation of primary PM appears to be the most efficient way for increasing health benefits, i.e., providing the largest mortality reduction per unit emissions. However, reductions in emissions of NH 3 are needed to maximize the effectiveness of NO x emission controls.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Traffic Signal Control for Large-Scale Urban Traffic Networks: Real-World Experiments using Vision-Based Sensors

Effective control of traffic signals plays a critical role in ensuring smooth vehicle flow in urban areas. Expertly engineered traffic signal controllers can considerably minimize travel delays and enhance sustainability. In this paper, the team proposes the Model Predictive Control (MPC) traffic signal control strategy using real-time traffic flow data from a vision-based camera as feedback information. Also, a realistic signal timing plan that considers National Electrical Manufacturers Association (NEMA) constraints has been developed to be applied to real-world scenarios. The primary aim is to reduce the number of vehicles across all links in the controlled area, thereby optimizing traffic flow and reducing energy consumption. To validate the proposed method, several real-life experiments were conducted at 24 intersections in Chattanooga, Tennessee, by collaborating with traffic field engineers. These experiments demonstrated significant performance improvements in comparison to the existing method.

data processing↗
DOE OSTI2020

Screening of Potential Biomass-Derived Streams as Fuel Blendstocks for Mixing Controlled Compression Ignition Combustion

Mixing controlled compression ignition or diesel engines are highly efficient and are likely to continue to be the primary means for movement of goods for many years to come. Low-carbon biofuels have the potential to significantly reduce the carbon footprint of diesel combustion and could potentially have advantageous properties for combustion such as high cetane number and reduced engine out particle emissions. In this study, we developed a list of potential biomass-derived diesel blendstocks. An online database of properties and characteristics of these bioblendstocks was populated with data. Fuel properties were determined by measurement, model prediction, or literature review. Screening criteria were developed to determine if a bioblendstock met the basic requirements for handling in the diesel distribution system and use as a blend with conventional diesel. Criteria included cetane number =40, flashpoint =52 degrees C, and boiling point or final boiling point <338 degrees C. Blendstocks needed to be soluble in diesel fuel, have a toxicity no worse than conventional diesel, and not be corrosive. Additionally, cloud point or freezing point below 0 degrees C was required. This screening produced a list of 27 potential bioblendstocks. Of these candidates, 13 were available commercially or could be synthesized by biofuels production researchers and included 11 nominally pure components and two mixtures. These 13 candidates were then subjected to further study based on how they impact fuel properties upon blending. Blend properties included cetane number, lubricity, conductivity, oxidation stability and viscosity. Results indicate that all thirteen candidates can meet the basic requirements for diesel fuel blending and are likely to reduce particle emissions from diesel combustion.

09 BIOMASS FUELS↗
DOE OSTI2024

Risk Analysis for Remote Operation of Microreactors

Microreactors are a subset of advanced nuclear reactors that can be factory fabricated, transportable, and self-regulating. They have the potential to be used in microgrids, rural and remote areas, or emergency response applications, replacing fossil fuel sources like diesel generators and enabling sustainable energy generation. In order to make microreactor operation cost-effective, it is likely that remote communications will be needed to reduce the number of personnel required to be on site. While remote operation of energy generation and other industrial control systems is common in other industries, it is not yet adopted in the nuclear community and has many perceived and actual risks. In this paper, the severity of the risks introduced by remote operations for microreactors are explored. The primary changes in the operations involve the addition of a remote communications network and a certification system for data and controls. These changes lend themselves to considerations of cyber risks, whether unintentional or adversarial, but the assessment considers not just cyber risks introduced, but also how physical and human factors-based risks will impact the remote operations system and change the overall risk profile. This initial assessment indicates that there are standard cyber and mitigation measures that can be put in place so the risk of doing remote operations does not dramatically increase compared to local operations. This evaluation is a critical step in the process of evaluating if remote operations of microreactors is a suitable solution to meet future sustainable grid needs

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2007

The Calipso Thermal Control Subsystem

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is a joint NASA-CNES mission to study the Earth s cloud and aerosol layers. The satellite is composed of a primary payload (built by Ball Aerospace) and a spacecraft platform bus (PROTEUS, built by Alcatel Alenia Space). The thermal control subsystem (TCS) for the CALIPSO satellite is a passive design utilizing radiators, multi-layer insulation (MLI) blankets, and both operational and survival surface heaters. The most temperature sensitive component within the satellite is the laser system. During thermal vacuum testing of the integrated satellite, the laser system s operational heaters were found to be inadequate in maintaining the lasers required set point. In response, a solution utilizing the laser system s survival heaters to augment the operational heaters was developed with collaboration between NASA, CNES, Ball Aerospace, and Alcatel-Alenia. The CALIPSO satellite launched from Vandenberg Air Force Base in California on April 26th, 2006. Evaluation of both the platform and payload thermal control systems show they are performing as expected and maintaining the critical elements of the satellite within acceptable limits.

Gasbarre, Joseph F.↗