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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Assessment and Optimization of Lidar Measurement Availability for Wind Turbine Control (Poster)

Integrating Lidar to improve wind turbine controls is a potential breakthrough for reducing the cost of wind energy. By providing undisturbed wind measurements up to 400m in front of the rotor, Lidar may provide an accurate update of the turbine inflow with a preview time of several seconds. Focusing on loads, several studies have evaluated potential reductions using integrated Lidar, either by simulation or full scale field testing.

17 WIND ENERGY↗
DOE OSTI2015

Assessment of future changes in water availability and aridity

Substantial changes in the hydrological cycle are projected for the 21st century, but these projections are subject to major uncertainties. In this context, the “dry gets drier, wet gets wetter” (DDWW) paradigm is often used as a simplifying summary. However, recent studies cast doubt on the validity of the paradigm and also on applying the widely used P-E (precipitation - evapotranspiration) metric over global land surfaces. Here we show in a comprehensive CMIP5-based assessment that projected changes in mean annual P - E are generally not significant, except for high-latitude regions showing wetting conditions until the end of the 21st century. Significant increases in aridity do occur in many subtropical and also adjacent humid regions. However, combining both metrics still shows that approximately 70% of all land area will not experience significant changes. Finally, based on these findings, we conclude that the DDWW paradigm is generally not confirmed for projected changes in most land areas.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Assessing groundwater availability and the response of the groundwater system to intensive exploitation in the North China Plain by analysis of long-term isotopic tracer data

The use of isotope tracers as a tool for assessing aquifer responses to intensive exploitation is demonstrated and used to attain a better understanding of the sustainability of intensively exploited aquifers in the North China Plain. Eleven well sites were selected that have long-term (years 1985–2014) analysis data of isotopic tracers. The stable isotopes δ{sup 18}O and δ{sup 2}H and hydrochemistry were used to understand the hydrodynamic responses of the aquifer system, including unconfined and confined aquifers, to groundwater abstraction. The time series data of {sup 14}C activity were also used to assess groundwater age, thereby contributing to an understanding of groundwater sustainability and aquifer depletion. Enrichment of the heavy oxygen isotope ({sup 18}O) and elevated concentrations of chloride, sulfate, and nitrate were found in groundwater abstracted from the unconfined aquifer, which suggests that intensive exploitation might induce the potential for aquifer contamination. The time series data of {sup 14}C activity showed an increase of groundwater age with exploitation of the confined parts of the aquifer system, which indicates that a larger fraction of old water has been exploited over time, and that the groundwater from the deep aquifer has been mined. The current water demand exceeds the sustainable production capabilities of the aquifer system in the North China Plain. Some measures must be taken to ensure major cuts in groundwater withdrawals from the aquifers after a long period of depletion.

58 GEOSCIENCES↗
DOE OSTI2019

Impact of Blend Proportion on the Miscibility and Thermal Characteristics of Synthetic Plastic-Derived Polypentapeptide with Commercially Available Polyvinyl Alcohol

Plastic-based polypeptides are versatile entities formed to conceive a broad range of scaffold biomaterials. They possess distinct, repetitive, hydrophobic sequences that confer conservation, reversibility, temperature-dependent self-association and dissociation properties. The repeating sequence of plastic-based peptides, poly(AVGVP) have been synthesized by the solution phase method and characterized by {sup 13}C and {sup 1}H-NMR spectroscopy. The intermolecular interactions between poly(AVGVP) and polyvinyl alcohol (PVA) was explored in solution and solid phase by diverse analytical methods. The interaction parameters, namely; α, β, µ and ∆[η]{sub m} obtained from the dilute solution viscometric approach, unveiled that the two polymers were miscible up to 40% of the polypeptide in the blends. Besides, Fourier transform infrared (FTIR) spectroscopy authenticated the formation of strong intermolecular hydrogen bonds connecting blend networks. Further, other analytical techniques such as DSC, SEM and XRD probes advocated the miscibility results. Thermogravimetric investigation of the blends confirmed the proportionate decrease of the thermal stability with the increase of polypentapeptide, attributable to the intermolecular amalgamation between the polypeptide and PVA. The blends and plain poly(AVGVP) degraded completely at about 700 °C, whereas the virgin PVA was about only 60% at this temperature. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2014

Modeled Impacts of Cover Crops and Vegetative Barriers on Corn Stover Availability and Soil Quality

Environmentally benign, economically viable, and socially acceptable agronomic strategies are needed to launch a sustainable lignocellulosic biofuel industry. Our objective was to demonstrate a landscape planning process that can ensure adequate supplies of corn (Zea mays L.) stover feedstock while protecting and improving soil quality. The Landscape Environmental Assessment Framework (LEAF) was used to develop land use strategies that were then scaled up for five U.S. Corn Belt states (Nebraska, Iowa, Illinois, Indiana, and Minnesota) to illustrate the impact that could be achieved. Our results show an annual sustainable stover supply of 194 million Mg without exceeding soil erosion T values or depleting soil organic carbon [i.e., soil conditioning index (SCI)?>?0] when no-till, winter cover crop, and vegetative barriers were incorporated into the landscape. A second, more rigorous conservation target was set to enhance soil quality while sustainably harvesting stover. By requiring erosion to be <1/2 T and the SCI-organic matter (OM) subfactor to be >?0, the annual sustainable quantity of harvestable stover dropped to148 million Mg. Examining removal rates by state and soil resource showed that soil capability class and slope generally determined the effectiveness of the three conservation practices and the resulting sustainable harvest rate. This emphasizes that sustainable biomass harvest must be based on subfield management decisions to ensure soil resources are conserved or enhanced, while providing sufficient biomass feedstock to support the economic growth of bioenergy enterprises.

09 BIOMASS FUELS↗
DOE OSTI2017

Letter to the Editor: Use of Publicly Available Image Resources

Here we write with regard to the Academic Radiology article entitled, “Computer-aided Diagnosis for Lung Cancer: Usefulness of Nodule Heterogeneity” by Drs. Nishio and Nagashima (1). The authors also report on a computerized method to classify as benign or malignant lung nodules present in computed tomography (CT) scans.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Optimal subhourly electricity resource dispatch under multiple price signals with high renewable generation availability

This article proposes a system-wide optimal resource dispatch strategy that enables a shift from a primarily energy cost-based approach, to a strategy using simultaneous price signals for energy, power and ramping behavior. A formal method to compute the optimal sub-hourly power trajectory is derived for a system when the price of energy and ramping are both significant. Optimal control functions are obtained in both time and frequency domains, and a discrete-time solution suitable for periodic feedback control systems is presented. The method is applied to North America Western Interconnection for the planning year 2024, and it is shown that an optimal dispatch strategy that simultaneously considers both the cost of energy and the cost of ramping leads to significant cost savings in systems with high levels of renewable generation: the savings exceed 25% of the total system operating cost for a 50% renewables scenario.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗