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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Network Modeling of the U.S. Petrochemical Industry under Raw Material and Hurricane Harvey Disruptions

A geographically resolved network model of the U.S. chemical industry in 2017 is designed, and optimal chemical flows between units are calculated using linear programming. A baseline solution and three disruption scenarios (primary raw material disruptions, reported Hurricane Harvey ethylene cracker disruptions, and assumed capacity disruptions based on the Hurricane Harvey geographic storm track) are reported on to determine how the structure of the industry is modified to adapt to widespread and geographically specific disruptions. The calculated impacts of the assumed Hurricane Harvey disruption include 170 chemical units in 26 states that change production level as a result of supply chain disruptions during the storm. The systemic impact for the assumed Hurricane Harvey disruption is 19.3 million tonnes of gross chemical production. The day with the largest impact on gross chemical production shows a reduction from baseline operations of 1.3 million tonnes (42% of baseline). This model can be utilized for analysis of future disruption scenarios and to test resilience strategies, including impacts of new manufacturing configurations or technologies.

02 PETROLEUM↗
DOE OSTI2026

Direct and rapid uranium isotopic analysis of environmental sample swipes via microextraction – LS-APGD/Orbitrap mass spectrometry

Accurate and precise isotopic analysis of actinides collected on environmental sample swipes from within nuclear facilities is an important safeguarding measure for detecting undeclared materials and activities. Traditional isotope ratio (IR) analysis of actinides using a bulk digestion approach can be laborious and time-consuming. Recently, direct analysis of environmental swipe samples using a microextraction approach has been explored as an alternative to conventional bulk digestion methods. The present study further evaluates this approach for accurate and precise isotopic analysis of uranium (U) in cotton swipe samples using the liquid sampling-atmospheric pressure glow discharge (LS-APGD)/Orbitrap-FTMS Booster detection system. The instrumental parameters were optimized, and quantitative capabilities were demonstrated through excellent linearity (R2 = 0.99) across a deposited mass range of 1 to 500 ng, with a limit of detection of 90 pg (in a 2 × 4 mm region) for total U; well below typical U concentrations (ng–mg range) in environmental sample swipes. The 235U/238U ratio showed excellent accuracy (−0.3% relative difference from the certificate value), with ∼20× improvement over previous microextraction-Orbitrap methods. Precision (∼1% relative standard deviation) was also greatly enhanced by ∼5×. This study also demonstrates that figures of merit achieved with neat U solution were not highly degraded when various external interfering elements/matrices were introduced. Finally, the developed method was successfully applied to analyze practical swipe samples representative of laboratory and outdoor environments. The presented figures of merit and applicability to practical samples further validate the capability of the platform for rapid analysis (<7 minutes) of environmental swipe samples.

Shrestha, Suraj [Clemson University, SC]↗
DOE OSTI2014

Intrinsic delay of permeable base transistor

Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.

36 MATERIALS SCIENCE↗
DOE OSTI2014

High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoid the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

The geostatistical approach for structural and stratigraphic framework analysis of offshore NW Bonaparte Basin, Australia

Geostatistics or statistical approach is based on the studies of temporal and spatial trend, which depend upon spatial relationships to model known information of variable(s) at unsampled locations. The statistical technique known as kriging was used for petrophycial and facies analysis, which help to assume spatial relationship to model the geological continuity between the known data and the unknown to produce a single best guess of the unknown. Kriging is also known as optimal interpolation technique, which facilitate to generate best linear unbiased estimation of each horizon. The idea is to construct a numerical model of the lithofacies and rock properties that honor available data and further integrate with interpreting seismic sections, techtonostratigraphy chart with sea level curve (short term) and regional tectonics of the study area to find the structural and stratigraphic growth history of the NW Bonaparte Basin. By using kriging technique the models were built which help to estimate different parameters like horizons, facies, and porosities in the study area. The variograms were used to determine for identification of spatial relationship between data which help to find the depositional history of the North West (NW) Bonaparte Basin.

58 GEOSCIENCES↗
DOE OSTI2017

Magnetic field production via the Weibel instability in interpenetrating plasma flows

Here, many astrophysical systems are effectively “collisionless,” that is, the mean free path for collisions between particles is much longer than the size of the system. The absence of particle collisions does not preclude shock formation, however, as shocks can be the result of plasma instabilities that generate and amplify electromagnetic fields. The magnetic fields required for shock formation may either be initially present, for example, in supernova remnants or young galaxies, or they may be self-generated in systems such as gamma-ray bursts (GRBs). In the case of GRB outflows, the Weibel instability is a candidate mechanism for the generation of sufficiently strong magnetic fields to produce shocks. In experiments on the OMEGA Laser, we have demonstrated a quasi-collisionless system that is optimized for the study of the non-linear phase of Weibel instability growth. Using a proton probe to directly image electromagnetic fields, we measure Weibel-generated magnetic fields that grow in opposing, initially unmagnetized plasma flows. The collisionality of the system is determined from coherent Thomson scattering measurements, and the data are compared to similar measurements of a fully collisionless system. The strong, persistent Weibel growth observed here serves as a diagnostic for exploring large-scale magnetic field amplification and the microphysics present in the collisional–collisionless transition.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

HyKKT: a hybrid direct-iterative method for solving KKT linear systems

Here, we propose a solution strategy for the large indefinite linear systems arising in interior methods for nonlinear optimization. The method is suitable for implementation on hardware accelerators such as graphical processing units (GPUs). The current gold standard for sparse indefinite systems is the LBLT factorization where L is a lower triangular matrix and B is 1×1 or 2×2 block diagonal. However, this requires pivoting, which substantially increases communication cost and degrades performance on GPUs. Our approach solves a large indefinite system by solving multiple smaller positive definite systems, using an iterative solver on the Schur complement and an inner direct solve (via Cholesky factorization) within each iteration. Cholesky is stable without pivoting, thereby reducing communication and allowing reuse of the symbolic factorization. We demonstrate the practicality of our approach on large optimal power flow problems and show that it can efficiently utilize GPUs and outperform LBL T factorization of the full system.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

The high-power helicon program at DIII-D: gearing up for first experiments

Helicon current drive, also called fast wave current drive in the lower hybrid range of frequencies, has long been regarded as a promising current drive tool for reactor grade plasmas. A newly installed MW-level system at DIII-D will be the first test of this technology in reactor-relevant plasmas, in the sense that full single-pass absorption is expected. A 30-module traveling wave antenna has been installed and optimized in-vessel in early 2020. The linear electromagnetic characteristics of the unloaded module array have been extensively tested both on the bench and in the vessel at instrumentation power levels. Excellent performance has been achieved, ~2% reflected power and ~1.5% dissipated power per module in air, in a 10 MHz band around 476 MHz. Stripline feeds on both ends of the antenna allow either co or counter current drive. The installation of a 1.2 MW klystron and associated high-power electronics was completed in Fall 2020. Commissioning of the antenna is ongoing. An important goal of this experiment is to validate the helicon current drive physics basis using an extensive set of new and upgraded diagnostics.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Status of ADRIANO R&D in T1015 Collaboration

The physics program for future High Energy and High Intensity experiments requires an energy resolution of the calorimetric component of detectors at limits of traditional techniques and an excellent particle identification. The novel ADRIANO technology (A Dualreadout Integrally Active Non-segmented Option), currently under development at Fermilab, is showing excellent performance on those respects. Results from detailed Monte Carlo studies on the performance with respect to energy resolution, linear response and transverse containment and a preliminary optimization of the layout are presented. A baseline configuration is chosen with an estimated energy resolution of σ(E)/E ≈ 30%/√E , to support an extensive R&D program recently started by T1015 Collaboration at Fermilab. Furthermore, preliminary results from several test beams at the Fermilab Test Beam Facility (FTBF) of a ~ 1λI prototype are presented. Future prospects with ultra-heavy glass are, also, summarized.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Detecting deviations from Gaussianity in high-redshift CMB lensing maps

ABSTRACT While the probability density function of the cosmic microwave background (CMB) convergence field approximately follows a Gaussian distribution, primordial non-Gaussianities, and small contributions from structures at low redshifts make the overall distribution slightly non-Gaussian. Some of the late-time component can be modelled using the distribution of galaxies and subtracted off from the original CMB lensing map to produce a map of matter distribution at high redshifts. Using this high-redshift mass map, we are able to directly study the early phases of structure formation. In this work, we forecast the detectability of signatures of non-Gaussianity due to non-linear structure formation at z > 1.2. Assuming the optimal case of no systematics, we find that it is challenging to detect such signatures in current surveys, but future experiments such as the deep field of CMB-S4 will be able to make detections of ∼7σ.

Astronomy & Astrophysics↗
DOE OSTI2021

Sequential Perturbation-based FDIA Detection using DERs for Unbalanced Distribution System

The power distribution system with its reliance on automated monitoring and control infrastructure makes it a complicated cyber-physical system and vulnerable to various cyber-attacks. This paper proposes a moving target defense inspired false data injection attack (FDIA) detection mechanism for an unbalanced distribution system. In the proposed grid diagnosis service framework, the distribution system operator judiciously manipulates power outputs of a subset of inverter-based distribution energy resources (DERs) to create secret low magnitude voltage perturbations which are inconsequential to the normal operation of the grid. A mixed-integer-linear-programming algorithm is developed to select the optimal set of DERs that can create a voltage perturbation signal of the required magnitude at each sensor location at a minimum cost. Then, a sequential detector is applied that detects for the FDIA as measurements are received from individual sensors. The performance of the proposed perturbation-based FDIA detection framework is demonstrated via simulation of the IEEE 123 bus test system.

Attack Detection↗
DOE OSTI2019

Community Microgrid Planning Considering Building Thermal Dynamics

In this paper, the building thermal dynamic characteristics are introduced in the community microgrid (MG) planning model. The proposed planning model is formulated as a mixed integer linear programming (MILP) which seeks to determine the optimal deployment strategy for various distributed energy resources (DER). The objective is to minimize the annualized cost of community MG, including investment cost in DER, operation cost for dispatchable fuel-generators (DFG), energy storage system (ESS) degradation cost, energy purchasing and peak demand charge at PCC, customer discomfort cost due to the room temperature deviation and load curtailment cost. Given the slow thermal dynamic characteristics of buildings, the heating, ventilation and air-conditioning (HVAC) system in the proposed model is treated as a demand side management (DSM) component, whose dispatch commands are provided by the central MG controller. Numerical results based on a community MG comprising of 20 residential buildings demonstrate the effectiveness of the proposed planning model and the benefits of introducing the building thermal dynamic model.

Zhang, Xiaohu↗
DOE OSTI2025

Improving Resiliency in Planning MW-Scale Medium and Heavy Duty EV Charging Stations Considering TSCOTS Optimization

Electrification of heavy-duty (HD) vehicles marks an important milestone and technical challenge in the electric vehicle (EV) industry and the public grid. However, implementing EV charging at this scale will necessitate that traditional truck stops be updated with EV charging infrastructure that could represent 10's of MW in electricity consumption. Furthermore, as the transportation sector is represented as critical infrastructure, supporting resiliency considerations in EV charging infrastructure will be critical. This paper proposes an optimization-based approach for optimally designing a MW-scale microgrid charging network. This approach transforms conventional designed truck stops into a reliable HDEV charging stations capable of overnight slow charging and 30-minute to 1 hour fast charging. Using a mixed-integer linear program formulation blending capacity planning and reliability constraints, an optimal network configuration can be solved for a proposed EV charging station that includes photovoltaic and battery energy storage capabilities.

Ponce, Moises [University of Tennessee, Knoxville ↗
DOE OSTI2018

Restoration using Distributed Energy Resources for Resilient Power Distribution Networks

In this paper, we propose a restorative method to minimize the unserved demand in a power distribution network where some islands are formed due to multiple line outages. The restoration is achieved by tie-line switching and by solving a mixed-integer non-linear problem. Due to combinatorial issues of the optimization problem, a method is proposed which restores the system by setting up microgrids boundaries within the islands and connecting them through tie-lines for exchange of active power in between them. The optimal tie-line to interconnect the microgrids is decided through information exchange between the microgrid operators. Case studies on IEEE 33-bus distribution network is presented to illustrate the results and validate the performance of the proposed method.

Sarkar, Ranadhir↗
DOE OSTI2013

Architectures and Control of Submodule Integrated DC-DC Converters for Photovoltaic Applications

This paper describes photovoltaic (PV) module architectures with parallel-connected submodule-integrated dc-dc converters (subMICs) that improve efficiency of energy capture in the presence of partial shading or other mismatch conditions. The subMICs are bidirectional isolated dc-dc converters capable of injecting or subtracting currents to balance the module substring voltages. When no mismatches are present, the subMICs are simply shut down, resulting in zero insertion losses. It is shown that the objective of minimum subMIC power processing can be solved as a linear programming problem. A simple close-to-optimal distributed control approach is presented that allows autonomous subMIC control without the need for a central controller or any communication among the subMICs. Furthermore, the proposed control approach is well suited for an isolated-port architecture, which yields additional practical advantages including reduced subMIC power and voltage ratings. The architectures and the control approach are validated by simulations and experimental results using three bidirectional flyback subMICs attached to a standard 180-W, 72-cell PV module, yielding greater than 98% module-level power processing efficiency for a mismatch less than 25%.

Olalla, C↗
DOE OSTI2017

A Geometric Approach to Aggregate Flexibility Modeling of Thermostatically Controlled Loads

Coordinated aggregation of a large population of thermostatically controlled loads (TCLs) presents a great potential to provide various ancillary services to the grid. One of the key challenges in coordination and control of TCLs is developing a simple and portable model to accurately extract their aggregate flexibility. In this paper, we propose a novel geometric approach to model the aggregate flexibility of TCLs. We show that the set of admissible power profiles of an individual TCL is a polytope, and their aggregate flexibility is the Minkowski sum of the individual polytopes. In order to represent their aggregate flexibility in an intuitive way and achieve a tractable approximation, we develop optimization-based algorithms to approximate the polytopes by the homothets of a given convex set. As a special application, this set is chosen as a virtual battery model and the corresponding optimal approximation problems are solved efficiently by equivalent linear programs. Numerical results show that our algorithms yield significant improvement in characterizing the aggregate flexibility over existing modeling methods. Finally, we also conduct case studies to demonstrate the efficacy of our approaches by coordinating TCLs to track a frequency regulation signal from the Pennsylvania-New Jersey-Maryland (PJM) Interconnection.

24 POWER TRANSMISSION AND DISTRIBUTION↗