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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Electrically heated particulate filter with zoned exhaust flow control

A system includes a particulate matter (PM) filter that includes X zones. An electrical heater includes Y heater segments that are associated with respective ones of the X zones. The electrical heater is arranged upstream from and proximate with the PM filter. A valve assembly includes Z sections that are associated with respective ones of the X zones. A control module adjusts flow through each of the Z sections during regeneration of the PM filter via control of the valve assembly. X, Y and Z are integers.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Energy Simulation of Integrated Multiple-Zone Variable Refrigerant Flow System

We developed a detailed steady-state system model, to simulate the performance of an integrated five-zone variable refrigerant flow (VRF)heat pump system. The system is multi-functional, capable of space cooling, space heating, combined space cooling and water heating, and dedicated water heating. Methods were developed to map the VRF performance in each mode, based on the abundant data produced by the equipment system model. The performance maps were used in TRNSYS annual energy simulations. Using TRNSYS, we have successfully setup and run cases for a multiple-split, VRF heat pump and dehumidifier combination in 5-zone houses in 5 climates that control indoor dry-bulb temperature and relative humidity. We compared the calculated energy consumptions for the VRF heat pump against that of a baseline central air source heat pump, coupled with electric water heating and the standalone dehumidifiers. In addition, we investigated multiple control scenarios for the VRF heat pump, i.e. on/off control, variable indoor air flow rate, and using different zone temperature setting schedules, etc. The energy savings for the multiple scenarios were assessed.

Energy Modeling↗
DOE OSTI2019

Analysis of climate zones’ effects on energy consumption of a bedroom TAC system

To promote the application of bedroom TAC to a larger region, task/ambient air conditioning (TAC) system was applied to different climate zones in China. In this study, China as a typical country which has a very large area and significantly different climate zones, was selected as the investigated country. Firstly, five cities in different climate zones were selected. Secondly, the CFD study was carried out on the bedroom TAC using the environmental parameters. Thirdly, predictive models of energy consumption were established using RSM method. Afterwards, the energy performance of the TAC system in different cities were predicted and analyzed. The results showed that the energy consumption in the typical day was from 0 kJ in Kunming to 4588.30 kJ in Shanghai.

Mao, Ning↗
DOE OSTI2021

Weather and Random Forest-based Load Profiling Approximation Models and its Transferability across Climate Zones

This study is to provide predictive understanding of the associations of various weather attributes with residential and commercial load profiles, for a variety of climate zones and seasons. In this work, machine learning (ML) approaches were used to identify and quantify the impacts of various weather attributes on residential and commercial electricity demand and its components across the western United States. Performance and transferability of the developed ML models were then evaluated across different temperate zones (e.g., southern, middle, and northern US) and across coastal, mid-continent, and wet zones, with inputs of weather condition data from the National Oceanic and Atmospheric Administration (NOAA) at representative weather stations. The predictive models were developed based on the ranked/screened factors using the regression tree (RT) and random forest (RF) approaches, for five different scenarios (seasons).

load composite, Random Forest, regression tree, lo↗
DOE OSTI2022

Analyses of the C. Winter #10 Enhanced Open-hole Drill Stem Test of the Residual Oil Zone in the Cypress Sandstone

The objective of this report is to detail enhanced open-hole drill stem test (DST) of the Residual Oil Zone in the Cypress Sandstone. DST are 1) to confirm there is no mobile oil from the suspected residual oil zone (ROZ), 2) estimate vertical and horizontal permeability in the ROZ, and 3) test vertical communication between the Cypress main pay zone (MPZ) and the ROZ, across the upper calcite layer.

02 PETROLEUM↗
DOE OSTI2019

Stress-Induced Porewater Pressures in the Vadose Zone Beneath a Mixed Waste Landfill - 19001

Increases in pore water pressure were detected in the vadose zone at two of eight monitoring points approximately 3 m below the bottom of a double liner for a landfill used for disposal of mixed waste at the Oak Ridge National Laboratory. Pressures were measured with pneumatic pressure transducers installed in the vadose zone to detect groundwater encroaching on the liner. The pressure increased concomitant with filling directly above the transducer, and ceased when waste reached final grades. The increase in pressure recorded by one transducer occurred 48 months later than the other transducer. The magnitude of pressure increase diminished with distance from a transect where an underdrain was constructed. Flows in the underdrain diminished over time, suggesting that the elevation of the groundwater table may have been dropping rather than increasing. Pore water pressures measured by the transducers exhibited a small seasonal periodicity mimicking that observed in underlying groundwater. Variably saturated flow analysis indicated that the seasonal periodicity can be attributed to pressures propagating upward in the vadose zone due to seasonal variations in elevation of the underlying groundwater table. The findings suggest that the pore water pressures measured with the pressure transducers are excess pore water pressures induced by the stress imposed by the overlying waste rather than a rise in the groundwater table. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Depth of the Biologically Active Zone in Terrestrial Habitats at the Chalk River Laboratories Site: Implications for Contaminated Site Assessment and Ecological Risk Assessment - 19272

Plants, soil invertebrates and burrowing mammals penetrate the soil layer to varying depths. As Canadian Nuclear Laboratories (CNL) assesses risks and remediates soils contaminated with radioactive and other hazardous wastes at the Chalk River Laboratories (CRL) site, a site-specific characterization of the biologically active zone is required to help to identify the relevant depth in soil for exposure assessment of ecological receptors. A defined biologically active zone is also required to determine the depth to which remedial actions should be taken to protect the environment, help prioritize locations for remediation efforts based on ecological risk and avoid unnecessary cleanup efforts. By taking advantage of the abundance of information on contaminant locations and depths, biodiversity, and hydrogeology available for the well-studied CRL site, it is possible to produce a site-specific estimation of the biologically active zone in CRL upland soils. A literature review was conducted to determine rooting and burrowing depths for vascular plants, soil invertebrates and burrowing mammals documented to be present (or potentially present) on the CRL site. This literature review was supplemented with field surveys to fill data gaps in our understanding of species composition (e.g., soil invertebrates and plant understory). Overall, we found that there was significant variability in maximum rooting/burrowing depths among plant, mammal and invertebrate species present on the CRL site. The majority of biological activity occurs in the top 0.5 m of soil. However, about 19% of burrowing or rooting receptors present at CRL may be in contact with soils up to 1 m depth, 9% of receptors present may be in contact with soils up to 2 m depth, and only about 2% of receptors may be in contact with soils up to 3 m depth. It is highly unlikely that any ecological receptor present at CRL is in direct contact with soils deeper than about 3.6 m. Further site-specific results pertaining to burrowing and rooting depths estimated for the CRL site will be presented, and these results will be compared to generic/default 'depth of biologically-active layer' guidelines recommended by various agencies. (authors)

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

Integrating Electrical Resistivity Tomography with Vadose Zone Characterization - 20246

The environmental management mission at the U.S. Department of Energy Hanford Site includes addressing subsurface contaminants that are present in the vadose zone because of historical waste discharges. Characterization is needed to support evaluation of whether contaminants at specific disposal sites will migrate to and contaminate the groundwater in the future. Drilling of boreholes and analysis of retrieved sediment samples is a standard approach to evaluating contaminant distribution in the vadose zone for the types of inorganic and radionuclide contaminants at the Hanford Site. However, borehole sampling has limitations for understanding the volumetric distribution of contaminants. The Hanford Site is now applying electrical resistivity tomography to characterize the path and volumetric extent of contaminant migration in the vadose zone. This information aids selection of appropriate locations for obtaining borehole samples and provides three-dimensional contaminant distribution information for incorporation into conceptual site models and to help configure fate and transport models. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Design of Zone-Based Hierarchical Protection System for 100% Renewable Microgrids: Preprint

Design of a reliable and secure protection system for a 100% renewable microgrid with only inverter-based resources (IBRs), is quite challenging. Most of the existing protection schemes in the state-of-the-art are suitable for microgrids with mixed-type of distributed energy resources (DERs) that covers both rotating machine-based DERs as well as IBR-based DERs, where the fault current level is moderately high. Due to drastic reduction in fault current level based on mode of operation and the variation of the low fault current level based on the operating level of the IBRs, the existing protection schemes face critical challenges, in case of a 100% renewable microgrid. This article proposes a zone-based hierarchical protection scheme that partitions a microgrid into various zones-of-protection and assigns speed-based hierarchical protection schemes in order to address the fundamental challenges of such microgrids. The performance of the proposed scheme is evaluated using time-domain simulation study on a microgrid test system. The results corroborates that the proposed hierarchical zone-based protection scheme exhibits enhanced reliability, security and dependability while tested with various fault cases (fault types, locations, and impedances), and non-fault cases during both grid-tied and islanded mode.

grid-forming inverter↗
DOE OSTI2017

Off-fault deformations and shallow slip deficit from dynamic rupture simulations with fault zone plasticity

Kinematic source inversions of major (M≥7) strike-slip earthquakes show that the slip at depth exceeds surface displacements measured in the field, and it has been suggested that this shallow slip deficit (SSD) is caused by distributed plastic deformation near the surface. We perform dynamic rupture simulations of M 7.2–7.4 earthquakes in elastoplastic media and analyze the sensitivity of SSD and off-fault deformation (OFD) to rock quality parameters. While linear simulations clearly underpredict observed SSD and OFDs, nonlinear simulations for a moderately fractured fault damage zone predict a SSD of 44–53% and OFDs of 39–48%, consistent with the 30–60% SSD and 46 ± 10% (1σ) OFD reported for the 1992 M 7.3 Landers earthquake. Finally, both SSD and OFDs are sensitive to the quality of the fractured rock mass inside the fault damage zone, and surface rupture is almost entirely suppressed in poor quality material.

58 GEOSCIENCES↗
DOE OSTI2023

Implementation of extrinsic cohesive zone model (ECZM) in 2D finite-discrete element method (FDEM) using node binding scheme

The combined finite-discrete element method (FDEM) has been widely used for rock fracturing simulations. Conventionally, FDEM is realized using the intrinsic cohesive zone model (ICZM); however, it has the drawback of artificial compliance and high computational expense. As a complement, the extrinsic cohesive zone model (ECZM) is seen to be realized in FDEM recently, whereas the node splitting scheme utilized is cumbersome. Here, within the framework of ICZM-based FDEM, we propose a node binding scheme to efficiently bind the pre-discretized finite elements and thus guarantee the continuum behavior of materials in the elastic stage. The yield surfaces, controlled by ECZM, are dynamically embedded by invoking the pre-inserted cohesive elements. The effectiveness and efficiency of the proposed approach are validated and tested by performing a suite of numerical experiments. Compared with ICZM-based FDEM, the proposed approach can correctly capture material deformation and reduce the computation cost. In contrast to the existing ECZM-based FDEM, the proposed approach can overcome the frequent and complex element topology updating. Finally, this work provides a novel perspective that fully inherits the advantages of both ICZM and ECZM, but circumvents their shortcomings, which guarantees a more efficient and effective simulation of brittle material evolution from continuum to discontinuum.

58 GEOSCIENCES↗
DOE OSTI2017

Accumulation of Fe oxyhydroxides in the Peruvian oxygen deficient zone implies non-oxygen dependent Fe oxidation

Oxygen minimum zones (OMZs) have been proposed to be an important source of dissolved iron (Fe) into the interior ocean. However, previous studies in OMZs have shown a sharp decrease in total dissolved Fe (dFe) and/or dissolved Fe(II) (dFe(II)) concentrations at the shelf-break, despite constant temperature, salinity and continued lack of oxygen across the shelf-break. The loss of both total dFe and dFe(II) suggests a conversion of the dFe to particulate form, but studies that have coupled the reduction-oxidation (redox) speciation of both dissolved and particulate phases have not previously been done. Here in this work, we have measured the redox speciation and concentrations of both dissolved and particulate forms of Fe in samples collected during the U.S. GEOTRACES Eastern tropical Pacific Zonal Transect (EPZT) cruise in 2013 (GP16). This complete data set allows us to assess possible mechanisms for loss of dFe. We observed an offshore loss of dFe(II) within the oxygen deficient zone (ODZ), where dissolved oxygen is undetectable, accompanied by an increase in total particulate Fe (pFe). Total pFe concentrations were highest in the upper ODZ. X-ray absorption spectroscopy revealed that the pFe maximum was primarily in the Fe(III) form as Fe(III) oxyhydroxides. The remarkable similarity in the distributions of total particulate iron and nitrite suggests a role for nitrite in the oxidation of dFe(II) to pFe(III). Lastly, we present a conceptual model for the rapid redox cycling of Fe that occurs in ODZs, despite the absence of oxygen.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

The Fragility of Bedform‐Induced Hyporheic Zones: Exploring Impacts of Dynamic Groundwater Table Fluctuations

Abstract Hyporheic zones are commonly regarded as resilient and enduring interfaces between groundwater and surface water in river corridors. In particular, bedform‐induced advective pumping hyporheic exchange (bedform‐induced exchange) is often perceived as a relatively persistent mechanism in natural river systems driving water, solutes, and energy exchanges between the channel and its surrounding streambed sediments. Numerous studies have been based on this presumption. To evaluate the persistence of hyporheic zones under varying hydrologic conditions, we use a multi‐physics framework to model advective pumping bedform‐induced hyporheic exchange in response to a series of seasonal‐ and event‐scale groundwater table fluctuation scenarios, which lead to episodic river‐aquifer disconnections and reconnections. Our results suggest that hyporheic exchange is not as ubiquitous as generally assumed. Instead, the bedform‐induced hyporheic exchange is restricted to a narrow range of conditions characterized by minor river‐groundwater head differences, is intermittent, and can be easily obliterated by minor losing groundwater conditions. These findings shed light on the fragility of bedform‐induced hyporheic exchange and have important implications for biogeochemical transformations along river corridors.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Ambient field seismology in critical zone hydrological sciences

Passive ambient noise monitoring is an emerging tool in environmental seismology, leveraging the ambient seismic field to assess temporal variations in shallow subsurface properties. This review focuses on the potential and challenges of using scattered coda waves from noise correlation functions to monitor critical zone dynamics. The sensitivity of seismic velocities to various environmental factors, including precipitation, snowmelt, atmospheric pressure, and groundwater fluctuations, underscores the method’s versatility. While coda waves excel in detecting subtle changes due to their scattered nature, ballistic waves provide higher spatial resolution, albeit with challenges in source stability. Advances in seismic sensing, including distributed acoustic sensing and low-cost geophone networks, have enabled high-resolution monitoring of hydrological processes, subsurface deformation, and seismic hazards. Integrating seismic data with hydrological models provides insights into water storage, pore pressure changes, and soil moisture dynamics. However, limitations in spatial resolution, calibration with ground truth data, and coupled effects between environmental factors remain key challenges. This review emphasizes the importance of interdisciplinary approaches in refining methodologies, enhancing sensor deployments, and addressing data gaps. Passive seismic monitoring offers opportunities to understand critical zone processes and their broader impacts on seismic hazards and environmental sustainability.

58 GEOSCIENCES↗
DOE OSTI2017

Thermal environment of the Southern Washington region of the Cascadia subduction zone

Eleven recently collected multichannel seismic (MCS) profiles from the Cascadia Open–Access Seismic Transects experiment offshore Washington State are used to characterize the distribution of bottom–simulating reflectors (BSRs) from seaward of the deformation front onto the continental shelf of the Cascadia Subduction Zone. The 11 MCS lines consisted of nine lines perpendicular and two lines parallel to the Cascadia margin covering a 100 km along–strike region of the accretionary wedge. From these MCS profiles we generated a 3–D view of the Cascadia margin thermal structure by interpreting 40,232 individual BSR picks in terms of temperature and heat flow. Overall BSR–derived heat flow values decrease from approximately 95 mW m –2 10 km east of the deformation front to approximately 60 mW m –2 located 60 km landward of the deformation front. Anomalously low heat flow values near 25 mW m –2 on a prominent midmargin terrace indicate recent sediment failure within the accretionary prism. Localized differences between BSR heat flow and numerical models reflect an estimated regional mean vertical fluid flow of +0.53 cm yr –1 for the survey area, with localized fluid flow approaching a maximum of +3.8 cm yr –1 . Distinct finite element models for the nine MCS profiles perpendicular to the deformation front reproduce BSR heat flow values, producing an overall root–mean–square misfit of 10.2 mW m –2 . In conclusion, at the deformation front, the incoming oceanic sediment/crust interface temperatures vary from 164°C to 179°C, indicating the updip limit of the Cascadia seismogenic zone.

58 GEOSCIENCES↗
DOE OSTI2022

Decoding the dynamics of poleward shifting climate zones using aqua-planet model simulations

Growing evidence indicates that the atmospheric and oceanic circulation experiences a systematic poleward shift in a warming climate. However, the complexity of the climate system, including the coupling between the ocean and the atmosphere, natural climate variability and land-sea distribution, tends to obfuscate the causal mechanism underlying the circulation shift. Here, using an idealised coupled aqua-planet model, we explore the mechanism of the shifting circulation, by isolating the contributing factors from the direct CO 2 forcing, the indirect ocean surface warming, and the wind-stress feedback from the ocean dynamics. We find that, in contrast to the direct CO 2 forcing, ocean surface warming, in particular an enhanced subtropical ocean warming, plays an important role in driving the circulation shift. This enhanced subtropical ocean warming emerges from the background Ekman convergence of surface anomalous heat in the absence of the ocean dynamical change. Additionally, it expands the tropical warm water zone, causes a poleward shift of the mid-latitude temperature gradient, hence forces a corresponding shift in the atmospheric circulation and the associated wind pattern. The shift in wind, in turn drives a shift in the ocean circulation. Our simulations, despite being idealised, capture the main features of the observed climate changes, for example, the enhanced subtropical ocean warming, poleward shift of the patterns of near-surface wind, sea level pressure, storm tracks, precipitation and large-scale ocean circulation, implying that increase in greenhouse gas concentrations not only raises the temperature, but can also systematically shift the climate zones poleward.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Multiscale cohesive zone model for propagation of segmented crack fronts in mode I+III fracture

Quasistatic crack propagation in mixed-mode I+III fracture is widely observed to be unstable, the instability being characterized by the segmentation of the parent crack into a periodic array of daughter cracks shaped as flat facets rotated towards the principal stress axis. While there has been recent progress to characterize this instability, no global theory is presently available to describe all aspects of the propagation of the segmented front, including both “local” features like the angle of rotation of the facets and the ratio of their width to their spacing, and “global” ones like the effective energy-release-rate of the segmented crack front and the tendency of the facets to coarsen. This paper embarks on the development of such a theory, based on the assumption that the spacing of the facets is much smaller than their length, and asymptotic matching of outer and inner solutions for the mechanical fields on scales comparable to the facet length and spacing, respectively. Here, the inner problem is shown to reduce to a 2D linear elastic fracture mechanics problem in the plane perpendicular to the crack propagation axis. The solution of this problem is used to develop an effective cohesive zone description of the crack front on a scale much larger than the facet spacing. Such a description leads to a system of 1D integral equations for the outer mechanical fields on the cohesive zone, which may be solved numerically. Numerical examples are given that notably illustrate the prediction of the effective energy-release-rate of the segmented crack front in terms of the various geometrical parameters; this energy-release-rate is predicted to be smaller for a segmented front than for the parent planar front, with the conclusion that segmentation acts as a toughening mechanism. Implications upon the phenomenon of facet coarsening are also briefly discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Massive to gauge field reduction and gravitational wave zone information

Here, I analyze the possible relevance of LIGO’s gravitational wave detection to the viability of massive gravity models. In GR, a wave zone, where the linearized approximation holds, is guaranteed to exist and the observed wave’s amplitude profile can be sufficiently related to the emitting strong field interior to confirm that, in this case, it was due to an inspiraling black hole merger. After an excursion to massive spin 1’s massless limit, linear massive tensor theory is shown explicitly to propagate only (retarded) maximal, helicity 2, modes to O(m) as m→0 , however, we don’t know if the full theory has a similar “wave zone” governed by the linear model. Even if it does, a much more serious obstacle for massive gravity is to construct a time-varying strong field event to compare with the strong field footprint of LIGO’s observed signals.

79 ASTRONOMY AND ASTROPHYSICS↗