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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Properties of Noise Cross-Correlation Functions Obtained from a Distributed Acoustic Sensing Array at Garner Valley, California

A field test that was conducted at Garner Valley, California, on 11 and 12 September 2013 using distributed acoustic sensing (DAS) to sense ground vibrations provided a continuous overnight record of ambient noise. Furthermore, the energy of ambient noise was concentrated between 5 and 25 Hz, which falls into the typical traffic noise frequency band. A standard procedure (Bensen et al., 2007) was adopted to calculate noise cross-correlation functions (NCFs) for 1-min intervals. The 1-min-long NCFs were stacked using the time–frequency domain phase-weighted-stacking method, which significantly improves signal quality. The obtained NCFs were asymmetrical, which was a result of the nonuniform distributed noise sources. A precursor appeared on NCFs along one segment, which was traced to a strong localized noise source or a scatterer at a nearby road intersection. NCF for the radial component of two surface accelerometers along a DAS profile gave similar results to those from DAS channels. Here, we calculated the phase velocity dispersion from DAS NCFs using the multichannel analysis of surface waves technique, and the result agrees with active-source results. We then conclude that ambient noise sources and the high spatial sampling of DAS can provide the same subsurface information as traditional active-source methods.

58 GEOSCIENCES↗
DOE OSTI2020

Developing Flexible, Networked Lighting Control Systems That Reliably Save Energy in California Buildings

An important strategy to meet California's ambitious energy efficiency goals is to use innovative wireless communications, embedded sensors, data analytics and controls to significantly reduce lighting energy use in commercial buildings. This project developed a suite of networked lighting solutions to further this goal. The technologies include a platform for low-cost sensing, distributed intelligence and communications, the “PermaMote,” which is a self-powered sensor and controller for lighting applications. The project team also developed a task ambient daylighting system that integrates sensors with data-driven daylighting control using an open communication interface, called the “Readings-At-Desk” (RAD) system. To address the problem of building occupants being confused about how to operate traditional lighting control systems, the research team created content that could be the basis for a user interface standard for lighting controls. Finally, to address the difficulty of ensuring that advanced lighting control systems actually deliver their promised energy savings, the project team developed a new method for evaluating and specifying lighting systems’ performance. The research team validated these technologies in the laboratory, showing significant lighting energy savings, up to 73% for the PermaMote sensor system from occupancy control and daylight dimming features, compared to the same light source (LED replacement lamps) operated via simple on/off scheduling. The project team also developed a proposed standard lighting data model and user interface elements, which were contributed to the ANSI Lighting Systems Committee (C137) for standardization. Existing data models are incomplete and inconsistent, whereas the lighting-specific data model developed here is clear and comprehensive, to serve as a starting point for creating common, universally agreed upon semantic definitions of key lighting parameters, to promote interoperability. For the task on verifiable performance of lighting systems, the project team developed a more effective metric for capturing the actual energy impact of a lighting system over time — the energy usage intensity (kWh/ft2/year). Three commercial lighting systems were tested in FLEXLAB® using this new metric, and the tests show a wide range in the accuracy of the self-reported energy-use metric, from 0.5% to 28% error compared to direct measurement of lighting energy using dedicated submeters. Overall, the project team estimates that these advanced technologies can reduce California office lighting energy use by 20% (above and beyond normal advanced lighting controls mandated by Title 24), resulting in about 1,600 GWh/year in savings.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

An Experimental Investigation of Distributed Acoustic Sensing (DAS) on Lake Ice

A vibration-sensitive, Distributed Acoustic Sensor (DAS) array, using fiber-optic cables, was deployed in a triangularly shaped geometry on the frozen surface of Lake Mendota in Madison, Wisconsin, USA. The purpose of the array and testing program was to analyze the DAS response and to utilize the high spatial density of the distributed array for system response characterization in a well-constrained, small, surface array. A geophone array was also deployed to provide a reference system. The design of the array allowed us to assess the response of DAS with respect to distance from the seismic sources, the degradation of the response with length of the cable, the directivity of the fiber response with respect of the direction of the particle motion, and the quality of the signal with respect to cable type. The DAS array was examined for different cable constructions and orientations relative to the source propagation direction. Tight-buffered and loose-tube fiber-optic cable constructions were used, with both having good signal responses when well-coupled to the ice. In general, the tight-buffered cable was better suited for DAS applications. Directional sensitivity of the DAS was also inspected for several directions of wave propagation and particle motion. The results showed that the strongest DAS signals were recorded when the direction of the fiber was oriented parallel to the direction of particle motion. Lastly, the DAS and geophone data sets were examined together to qualitatively determine, in conjunction with established DAS best practices, how the high spatial density offered by DAS could improve results over traditional point sensor arrays in certain situations.

15 GEOTHERMAL ENERGY↗
DOE OSTI2015

Quantification of water in majoritic garnet

Majoritic garnet, characterized by an excess of silicon (>3 Si per formula unit), is considered one of the major phases of the Earth’s transition zone from 410-660 km depth. Quantifying the H 2 O content of nominally anhydrous mantle minerals is necessary to evaluate their water storage capacity from experiments and modeling the Earth’s deep water cycle. We present mineral-specific infrared absorption coefficients for the purpose of quantifying the amount of water incorporated into majorite as hydroxyl point defects. A suite of majoritic garnet samples with varying proportions of Si, Fe, Al, Cr and H 2 O was synthesized at conditions of 18-19 GPa and 1500-1800°C. Single-crystals were characterized using X-ray diffraction, electron microprobe analysis, secondary Ion Mass spectrometry (SIMS), IR, Raman and Mössbauer spectroscopy. We utilize SIMS and Raman spectroscopy in combination with IR spectroscopy to provide IR absorption coefficients for water in majoritic garnets with the general mineral formula (Mg,Fe) 3 (Si,Mg,Fe,Al,Cr) 2 [SiO4] 3 . Furthermore, the IR absorption coefficient for majoritic garnet in the OH stretching region is frequency-dependent and ranges from 10 470 ± 3100 Lmol-1cm-2 to 23 400 ± 2300 Lmol -1 cm -2 .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Graduate Education for a New Sustainable Urban Systems Science: Designing a New PhD Curriculum Integrating Sustainability Science and Urban Science

This is a report on the discussions held during an NSF SUS conference “Graduate Education for a New Sustainable Urban Systems Science: Designing a New PhD Curriculum Integrating Sustainability Science and Urban Science”. The conference was motivated by the call made by the NSF for “…developing the next generation of sustainable urban systems science.” The conference was premised on the assumption that such continued development will have need for the training of new generations of urban sustainability scientists, and that both the content and manner of training will be different from established degree programs.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2019

Trihalomethane precursor reactivity changes in drinking water treatment unit processes during a storm event

Source water quality can significantly impact the efficacy of water treatment unit processes and the formation of chlorinated and brominated trihalomethanes (THMs). Current water treatment plant performance models may not accurately capture how source water quality variations, such as organic matter variability, can impact treatment unit processes. To investigate these impacts, a field study was conducted wherein water samples were collected along the treatment train for 72 hours during a storm event. Systematic sampling and detailed analyses of water quality parameters, including non-purgeable organic carbon (NPOC), UV absorbance, and THM concentrations, as well as chlorine spiking experiments, reveal how the THM formation potential changes in response to treatment unit processes. Results show that the NPOC remaining after treatment has an increased reactivity towards forming THMs, and that brominated THMs form more readily than chlorinated counterparts in a competitive reaction. Thus both the reactivity and quantity of THM precursors must be considered to maintain compliance with drinking water standards, a finding that should be incorporated into the development of model-assisted treatment operation and optimization. Advanced granular activated carbon (GAC) treatment beyond conventional coagulation–flocculation–sedimentation processes may also be necessary to remove the surge loading of THM-formation precursors during a storm event.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Cyber Threat Metrics

Threats are generally much easier to list than to describe, and much easier to describe than to measure. As a result, many organizations list threats. Fewer describe them in useful terms, and still fewer measure them in meaningful ways. This is particularly true in the dynamic and nebulous domain of cyber threats - a domain that tends to resist easy measurement and, in some cases, appears to defy any measurement. We believe the problem is tractable. In this report we describe threat metrics and models for characterizing threats consistently and unambiguously. The purpose of this report is to support the Operational Threat Assessment (OTA) phase of risk and vulnerability assessment. To this end, we focus on the task of characterizing cyber threats using consistent threat metrics and models. In particular, we address threat metrics and models for describing malicious cyber threats to US FCEB agencies and systems.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2012

Renewal of Collaborative Research: Economically Viable Forest Harvesting Practices That Increase Carbon Sequestration

Forests provide wildlife habitat, water and air purification, climate moderation, and timber and nontimber products. Concern about climate change has put forests in the limelight as sinks of atmospheric carbon. The C stored in the global vegetation, mostly in forests, is nearly equivalent to the amount present in atmospheric CO 2 . Both voluntary and government-mandated carbon trading markets are being developed and debated, some of which include C sequestration resulting from forest management as a possible tradeable commodity. However, uncertainties regarding sources of variation in sequestration rates, validation, and leakage remain significant challenges for devising strategies to include forest management in C markets. Hence, the need for scientifically-based information on C sequestration by forest management has never been greater. The consequences of forest management on the US carbon budget are large, because about two-thirds of the ≈300 million hectare US forest resource is classified as 'commercial forest.' In most C accounting budgets, forest harvesting is usually considered to cause a net release of C from the terrestrial biosphere to the atmosphere. However, forest management practices could be designed to meet the multiple goals of providing wood and paper products, creating economic returns from natural resources, while sequestering C from the atmosphere. The shelterwood harvest strategy, which removes about 30% of the basal area of the overstory trees in each of three successive harvests spread out over thirty years as part of a stand rotation of 60-100 years, may improve net C sequestration compared to clear-cutting because: (1) the average C stored on the land surface over a rotation increases, (2) harvesting only overstory trees means that a larger fraction of the harvested logs can be used for long-lived sawtimber products, compared to more pulp resulting from clearcutting, (3) the shelterwood cut encourages growth of subcanopy trees by opening up the forest canopy to increasing light penetration. Decomposition of onsite harvest slash and of wastes created during timber processing releases CO 2 to the atmosphere, thus offsetting some of the C sequestered in vegetation. Decomposition of soil C and dead roots may also be temporarily stimulated by increased light penetration and warming of the forest floor. Quantification of these processes and their net effect is needed. We began studying C sequestration in a planned shelterwood harvest at the Howland Forest in central Maine in 2000. The harvest took place in 2002 by the International Paper Corporation, who assisted us to track the fates of harvest products (Scott et al., 2004, Environmental Management 33: S9-S22). Here we present the results of intensive on-site studies of the decay of harvest slash, soil respiration, growth of the remaining trees, and net ecosystem exchange (NEE) of CO 2 during the first six years following the harvest. These results are combined with calculations of C in persisting off-site harvest products to estimate the net C consequences to date of this commercial shelterwood harvest operation. Tower-based eddy covariance is an ideal method for this study, as it integrates all C fluxes in and out of the forest over a large 'footprint' area and can reveal how the net C flux, as well as gross primary productivity and respiration, change following harvest. Because the size of this experiment precludes large-scale replication, we are use a paired-airshed approach, similar to classic large-scale paired watershed experiments. Measurements of biomass and C fluxes in control and treatment stands were compared during a pre-treatment calibration period, and then divergence from pre-treatment relationships between the two sites measured after the harvest treatment. Forests store carbon (C) as they accumulate biomass. Many forests are also commercial sources of timber and wood fiber. In most C accounting budgets, forest harvesting is usually considered to cause a net release of C from the terrestrial biosphere to the atmosphere. However, it might also be possible for commercial use of forests to contribute to terrestrial sequestration of C. The objective of the our research project is to determine whether shelterwood cutting regimes now being adopted in the commercial forests of Maine and other areas of the country can achieve these multiple goals.

09 BIOMASS FUELS↗
DOE OSTI2012

Recycling produced water for algal cultivation for biofuels

Algal growth demands a continuous source of water of appropriate salinity and nutritional content. Fresh water sources are scarce in the deserts of the Southwestern United States, hence, salt water algae species are being investigated as a renewable biofuel source. The use of produced water from oil wells (PW) could offset the demand for fresh water in cultivation. Produced water can contain various concentrations of dissolved solids, metals and organic contaminants and often requires treatment beyond oil/water separation to make it suitable for algae cultivation. The produced water used in this study was taken from an oil well in Jal, New Mexico. An F/2-Si (minus silica) growth media commonly used to cultivate Nannochloropsis salina 1776 (NS 1776) was prepared using the produced water (F/2-Si PW) taking into account the metals and salts already present in the water. NS 1776 was seeded into a bioreactor containing 5L of the (F/2-Si PW) media. After eleven days the optical density at 750 nm (an indicator of algal growth) increased from 0 to 2.52. These results indicate algae are able to grow, though inhibited when compared with non-PW media, in the complex chemical conditions found in produced water. Savings from using nutrients present in the PW, such as P, K, and HCO 3 -1 , results in a 44.38% cost savings over fresh water to mix the F/2-Si media.

02 PETROLEUM↗
DOE OSTI2012

Automated Comparison of Building Energy Simulation Engines [Slides]

This presentation describes the BEopt comparative test suite, which is a tool that facilitates the automated comparison of building energy simulation engines. It also demonstrates how the test suite is improving the accuracy of building energy simulation programs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

Identifying and Resolving Issues in EnergyPlus and DOE-2 Window Heat Transfer Calculations

Issues in building energy software accuracy are often identified by comparative, analytical, and empirical testing as delineated in the BESTEST methodology. As described in this report, window-related discrepancies in heating energy predictions were identified through comparative testing of EnergyPlus and DOE-2. Multiple causes for discrepancies were identified, and software fixes are recommended to better align the models with the intended algorithms and underlying test data.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

Advanced Palladium Membrane Scale-up for Hydrogen Separation

The main objective of this project was to construct, test, and demonstrate a Pd-Cu metallic tubular membrane micro-channel separator capable of producing 2 lb day -1 H 2 at 95% recovery when operating downstream of an actual coal gasifier. A key milestone for the project was to complete a pilot-scale gasifier test by 1 September 2011 and demonstrate the separation of 2 lb day -1 H 2 to verify progress toward the DOE's goals prior to down-selection for larger-scale (100 lb day -1 ) hydrogen separator development.

08 HYDROGEN↗
DOE OSTI2013

Advanced Neutron Generator For SNM Imaging

Associated particle imaging (API) is a neutron interrogation technique for detecting concealed or heavily shielded objects such as special nuclear material (SNM), explosives, and other contraband. In API, 14 MeV neutrons are formed in the deuterium–tritium fusion reaction along with an associated 3.5 MeV alpha particle that travels in the opposite direction of the neutron as a result of conservation of linear momentum. Characteristic signatures (gamma rays, fission neutrons, etc.) produced from neutron target reactions in the interrogated object provide information on the target material. In contrast to traditional neutron interrogation techniques, API is a “self-collimating” method in which the alpha particles are used to determine the position and direction of the emitted neutrons, thereby significantly reducing the background noise by only selecting events caused by neutrons emitted in the direction of the interrogated object.

Leung, Ka-Ngo↗
DOE OSTI2013

Investigation of the LiCaAlF 6 :Eu Scintillator Family for Next-Generation Neutron Detection (Annual Report)

LiCaAlF 6 :Eu (LiCAF:Eu) is a promising scintillator that possesses several fundamental advantages over CsLiYCl 6 :Ce (CLYC). This scintillator, however, is just one member of a much broader family of materials known as colquiriites, designated as LiMe II Me III F 6 , where Me II and Me III can be any number of divalent and trivalent cations, respectively. The LiCAF system has incredible potential for a wide variety of substitutions in the Me II and Me III sites, and its members are recognized as excellent hosts for luminescing activator dopants (e.g., Ce 3+ , Eu 2+ , Cr 3+ , Pb 2+ and Yb 2+ ) in order to tune the nuclear and luminescence performance in several ways. We intend to fully exploit this versatility by investigating the effects of substituting other alkali, alkali-earth, rare-earth, Group III, and Group XIII elements. The objective of this work is to explore the colquiriite system of scintillating materials, most notably LiCaAlF 6 :Eu, to identify and characterize new scintillators with improved scintillation performance, simplified crystal growth, and tunable neutron and gamma sensitivities.

Harrison, Mark J.↗
DOE OSTI2013

Monte-Carlo Generation of Time Evolving Fission Chains

About a decade ago, a computer code was written to model neutrons from their “birth” to their final “death” in thermal neutron detectors ( 3 He tubes): SrcSim had enough physics to track the neutrons in multiplying systems, appropriately increasing and decreasing the neutron population as they interacted by absorption, fission and leakage. The theory behind the algorithms assumed that all neutrons produced in a fission chain were all produced simultaneously, and then diffused to the neutron detectors. For cases where the diffusion times are long compared to the fission chains, SrcSim is very successful. Indeed, it works extraordinarily well for thermal neutron detectors and bare objects, because it takes tens of microseconds for fission neutrons to slow down to thermal energies, where they can be detected. Microseconds are a very long time compared to the lengths of the fission chains. However, this inherent assumption in the theory prevents its use to cases where either the fission chains are long compared to the neutron diffusion times (water-cooled nuclear reactors, or heavily moderated object, where the theory starts failing), or the fission neutrons can be detected shortly after they were produced (fast neutron detectors). For these cases, a new code needs to be written, where the underlying assumption is not made. The purpose of this report is to develop an algorithm to generate the arrival times of neutrons in fast neutron detectors, starting from a neutron source such as a spontaneous fission source ( 252 Cf) or a multiplying source (Pu). This code will be an extension of SrcSim to cases where correlations between neutrons in the detectors are on the same or shorter time scales as the fission chains themselves.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

Performance and Efficiency of Biomass Densification Equipment (CRADA Final Report)

In 2008, a CRADA between the INL and Vermeer was signed and work began between the two parties to look at improvements in grinding processes for agricultural crop residues. Preprocessing is a critical operation in the biomass feedstock assembly system of a lignocellulosic biorefinery. Preprocessing is typically accomplished using industrial grinders to grind, chop, or otherwise size-reduce biomass materials into a suitable feedstock for conversion to biofuels and bioproducts. Various components of commercial preprocessing equipment capable of handling large-format material (such as large square bales) can be modified or altered to change the overall productivity and efficiency of the process. Many factors affect machine capacity and efficiency and the physical characteristics of preprocessed biomass. Ultimately, grinder capacity and efficiency can be enhanced by selecting hammer and screen configurations that optimize grinder performance-based mass flow and energy consumption. Variations in grinder capacity and efficiency were evaluated by altering the type, number, and orientation of the hammer; the screen type and size; and the rotational drum speed of the grinder. Fuel use and grinder capacity were compared with each modification made to the grinder system and the original design of the horizontal grinder test platform. Modifications evaluated in this study resulted in a significant increase in grinder capacity and efficiency.

09 BIOMASS FUELS↗