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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 451 records · Page 25

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Rolling Horizon Based Temporal Decomposition for the Offline Pickup and Delivery Problem with Time Windows

The offline pickup and delivery problem with time windows (PDPTW) is a classical combinatorial optimization problem in the transportation community, which has proven to be very challenging computationally. Due to the complexity of the problem, practical problem instances can be solved only via heuristics, which trade-off solution quality for computational tractability. Among the various heuristics, a common strategy is problem decomposition, that is, the reduction of a large-scale problem into a collection of smaller sub-problems, with spatial and temporal decompositions being two natural approaches. While spatial decomposition has been successful in certain settings, effective temporal decomposition has been challenging due to the difficulty of stitching together the sub-problem solutions across the decomposition boundaries. In this work, we introduce a novel temporal decomposition scheme for solving a class of PDPTWs that have narrow time windows, for which it is able to provide both fast and high-quality solutions. We utilize techniques that have been popularized recently in the context of online dial-a-ride problems along with the general idea of rolling horizon optimization. To the best of our knowledge, this is the first attempt to solve offline PDPTWs using such an approach. To show the performance and scalability of our framework, we use the optimization of paratransit services as a motivating example. Due to the lack of benchmark solvers similar to ours (i.e., temporal decomposition with an online solver), we compare our results with an offline heuristic algorithm using Google OR-Tools. In smaller problem instances (with an average of 129 requests per instance), the baseline approach is as competitive as our framework. However, in larger problem instances (approximately 2,500 requests per instance), our framework is more scalable and can provide good solutions to problem instances of varying degrees of difficulty, while the baseline algorithm often fails to find a feasible solution within comparable compute times.

Kim, Youngseo↗

DOE OSTI2025

Effect of Time Window and Spectral Measurement Options on Empirical Green’s Function Analysis Using DAS Array and Seismic Stations

The recorded seismic waveform is a convolution of event source term, path term, and station term. Removing high-frequency attenuation due to path effect is a challenging problem. Empirical Green’s function (EGF) method uses nearly collocated small earthquakes to correct the path and station terms for larger events recorded at the same station. However, this method is subject to variability due to many factors. Here, we focus on three events that were well recorded by the seismic network and a rapid response distributed acoustic sensing (DAS) array. Using a suite of high-quality EGF events, we assess the influence of time window, spectral measurement options, and types of data on the spectral ratio and relative source time function (RSTF) results. Increased number of tapers (from 2 to 16) tends to increase the measured corner frequency and reduce the source complexity. Extended long time window (e.g., 30 s) tends to produce larger variability of corner frequency. The multitaper algorithm that simultaneously optimizes both target and EGF spectra produces the most stable corner-frequency measurements. The stacked spectral ratio and RSTF from the DAS array are more stable than two nearby seismic stations, and are comparable to stacked results from the seismic network, suggesting that DAS array has strong potential in source characterization.

58 GEOSCIENCES↗

DOE OSTI2014

RELAP5-3D developmental assessment: Comparison of version 4.2.1i on Linux and Windows

Figures have been generated comparing the parameters used in the developmental assessment of the RELAP5-3D code, version 4.2i, compiled on Linux and Windows platforms. The figures, which are the same as those used in Volume III of the RELAP5-3D code manual, compare calculations using the semi-implicit solution scheme with available experiment data. These figures provide a quick, visual indication of how the code predictions differ between the Linux and Windows versions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

RELAP5-3D Developmental Assessment. Comparison of Version 4.3.4i on Linux and Windows

Figures have been generated comparing the parameters used in the developmental assessment of the RELAP5-3D code, version 4.3i, compiled on Linux and Windows platforms. The figures, which are the same as those used in Volume III of the RELAP5-3D code manual, compare calculations using the semi-implicit solution scheme with available experiment data. These figures provide a quick, visual indication of how the code predictions differ between the Linux and Windows versions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

Electrochromic Window Demonstration at the Donna Land Port of Entry

The U.S. General Services Administration (GSA) Public Buildings Service (PBS) has jurisdiction, custody or control over 105 land ports of entry throughout the United States, 35 of which are located along the southern border. At these facilities, one of the critical functions of windows is to provide border control personnel with direct visual contact with the surrounding environment. This also can be done through surveillance cameras, but the high value that U.S. Customs and Border Protection (CPB) officers place on direct visual contact can be encapsulated in the following statement by a senior officer regarding this project: “nothing replaces line of sight.” In sunny conditions, however, outdoor visibility can be severely compromised by glare, especially when the orb of the sun is in the field of view. This often leads to the deployment of operable shading devices, such as Venetian blinds. While these devices address the glare, they obstruct the view of the surroundings, negating the visual security benefits of the windows.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Further Automate Planned Cluster Maintenance to Minimize System Downtime during Maintenance Windows

This report documents the integration and testing of the automated update process of compute clusters in LC to minimize impact to user productivity. Description: A set of scripts will be written and deployed to further standardize cluster maintenance activities and minimize downtime during planned maintenance windows. Completion Criteria: When the scripts have been deployed and used during planned maintenance windows and a timing comparison is completed between the existing process and the new more automated process, this milestone is complete. This milestone was completed on Aug 23, 2016 on the new CTS1 cluster called Jade when a request to upgrade the version of TOSS 3 was initiated while SWL jobs and normal user jobs were running. Jobs that were running when the update to the system began continued to run to completion. New jobs on the cluster started on the new release of TOSS 3. No system administrator action was required. Current update procedures in TOSS 2 begin by killing all users jobs. Then all diskfull nodes are updated, which can take a few hours. Only after the updates are applied are all nodes are rebooted, and then finally put back into service. A system administrator is required for all steps. In terms of human time spent during a cluster OS update, the TOSS 3 automated procedure on Jade took 0 FTE hours. Doing the same update without the Toss Update Tool would have required 4 FTE hours.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2016

Detection with Enhanced Energy Windowing Phase I Report

This document reviews the progress of Phase I of the Detection with Enhanced Energy Windowing (DEEW) project. The DEEW project is the implementation of software incorporating an algorithm which reviews data generated by radiation portal monitors and utilizes advanced and novel techniques for detecting radiological and fissile material while not alarming on Naturally Occurring Radioactive Material. Independent testing indicated that the Enhanced Energy Windowing algorithm showed promise at reducing the probability of alarm in the stream of commerce compared to existing algorithms and other developmental algorithms, while still maintaining adequate sensitivity to threats. This document contains a brief description of the project, instructions for setting up and running the applications, and guidance to help make reviewing the output files and source code easier.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2017

Catalog of Window Taper Functions for Sidelobe Control

Window taper functions of finite apertures are well-known to control undesirable sidelobes, albeit with performance trades. A plethora of various taper functions have been developed over the years to achieve various optimizations. We herein catalog a number of window functions, and com pare principal characteristics.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

DOE OSTI2017

Calculating the Effect of External Shading on the Solar Heat Gain Coefficient of Windows

Current prescriptive building codes have limited ways to account for the effect of solar shading, such as overhangs and awnings, on window solar heat gains. We propose two new indicators, the adjusted Solar Heat Gain Coefficient (aSHGC) which accounts for external shading while calculating the SHGC of a window, and a weighted SHGC (SHGCw) which provides a seasonal SHGC weighted by solar intensity. We demonstrate a method to calculate these indices using existing tools combined with additional calculations. The method is demonstrated by calculating the effect of an awning on a clear double glazing in New Delhi.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2018

Residual Stress Measurements of Front Window Welds in a Prototypical Spallation Neutron Source Target Module

Spallation Neutron Source (SNS) target modules are fabricated from 316L stainless steel by welding together sections of machined components using electron beam welding. The failure of the tenth operational SNS target (Target 10) at an electron beam weld prompted an investigation into the residual stress remaining in the weld joint after joining to determine if welding procedures for SNS target fabrication produce detrimental residual stresses in or near the welds. Due to an issue with fabrication, the front section of an SNS target was removed from fabrication and made available for residual stress measurements. The residual stresses in an electron beam weld joining the front window and front body of the target prototype was measured at several locations near EBW2 weld between outer window and front body using the VUCLAN instrument. Different stress free d hkl 0 methods were used to calculated the residual strain and residual stress. Furthermore, the results show tensile residual stress up to 350MPa along the weld direction which peaked at weld location.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Window Test Stand Status and Future Work [Slides]

Challenges to getting the window test stand running that were addressed. Initial design of half-anchor connector was insufficient. Accommodation of non-Rexolite windows required engineering.

42 ENGINEERING↗

DOE OSTI2022

Small Windowed PDV Slab Shot Verification

Windowed PDV probes are used as a time of arrival diagnostic where conventional PDV measurements cannot be made with accuracy i.e., measurements where the surface measured is bare HE or the surface measured does not provide quality optical return for PDV directly. Often hydro experiments require that these diagnostics be minimally invasive, so their installation does not negatively impact the device performance or the overall experiments goals. In this report we build 3 mm diameter windowed probes and show that they give an error that is still within the error of piezo pins.

13 HYDRO ENERGY↗

DOE OSTI2022

Paintable Heat-Reflective Coatings for Low-Cost Energy Efficient Windows

The major objective of this effort is to manufacture a paintable coating to inexpensively retrofit energy-inefficient windows with a heat-reflective, visibly transparent film. This coating will drastically reduce cooling costs for millions of homes and buildings and lower the Nation’s greenhouse gas emissions. Widespread implementation could reduce the national consumption of electricity for cooling by billions of kWh, saving billions of dollars per year. This improved energy efficiency would decrease CO2 emissions by billions kg per year, the equivalent to removing millions of cars from the road. Although near-IR reflective adhesive films are commercially available products and have demonstrated significant energy efficiency enhancement, high upfront costs largely deter potential consumers across all sectors. The technology developed under this award was proposed to disrupt the building envelope market, by providing an inexpensive coating that can be directly applied by consumers to improve the energy efficiency of virtually all window types. The proof of concept for a paintable, DIY applicable, visibly transparent, and infrared reflective coating was achieved, laying the foundation for future technology development in this area.

14 SOLAR ENERGY↗

DOE OSTI2024

DIY Affordable Window Shading

This document shows how you can easily and affordably shade your windows to keep your home from getting too hot on sunny days. This phenomenon (what researchers call “solar heat gain”) can threaten occupant comfort and safety, especially during heatwaves. Still, many homes lack adequate protection. All of these solutions can be implemented inexpensively using common household items or items that can easily be purchased online. Additionally, you don’t need specialized tools or expertise to install them. Note that these are ideally temporary fixes, so households with sufficient means should still pursue permanent ones (e.g.,shades—preferably on the outside—or specialized windows or films). In their absence, the stopgap measures described below can help protect you and your loved ones during heatwaves and other exceptional events.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2026

Preparing large area of thermochromic nanocomposite films for smart window application

The challenges posed by high building energy bill necessitate proactive implementation of energy-efficient strategies to minimize the uses of both electricity and heating gas and promote the use of free solar energy sources. "Smart" window films/glass, leveraging thermochromic vanadium dioxide (VO 2 ), offer an adaptive approach to harness solar energy, significantly reducing the thermal load of buildings. This is achieved by reflecting the infrared portion of the solar spectrum through a phase transition in the monoclinic M-phase (M) of VO 2 induced by heating. In this study, a scalable continuous flow synthesis process invented by Argonne was employed to explore a wide parameter space, targeting the controlled synthesis of monoclinic VO 2 (M) nanoparticles with well-controlled sizes and morphologies. Additionally, a doping strategy and surface modifications were utilized for high-throughput tuning of the metal-to-insulator transition temperature. Strategies to enhance the solar modulation properties of VO 2 nanoparticles in polymer films were investigated through (i) morphological transformation from spherical to nanorod structures, (ii) surface modification with low refractive index ligands, and (iii) incorporation of additional thermochromic materials for improved solar energy modulation and aesthetically appealing colors in smart films. Furthermore, the study outlines scaling-up synthesis methods for VO 2 nanoparticles in a continuous flow reactor using hydrazine monohydrate. This comprehensive investigation provides valuable insights into the upscaling synthesis and design of advanced VO 2 /polymer composite smart window films with enhanced functionality, solar energy modulation and visible light transmittance, driving the technology a step close for industrial application.

14 SOLAR ENERGY↗

DOE OSTI2014

Fuel Economy and Emissions Effects of Low Tire Pressure, Open Windows, Roof Top and Hitch-Mounted Cargo, and Trailer

To quantify the fuel economy (FE) effect of some common vehicle accessories or alterations, a compact passenger sedan and a sport utility vehicle (SUV) were subjected to SAE J2263 coastdown procedures. Coastdowns were conducted with low tire pressure, all windows open, with a roof top or hitch-mounted cargo carrier, and with the SUV pulling an enclosed cargo trailer. From these coastdowns, vehicle dynamometer coefficients were developed which enabled the execution of vehicle dynamometer experiments to determine the effect of these changes on vehicle FE and emissions over standard drive cycles and at steady highway speeds. The FE penalty associated with the rooftop cargo box mounted on the compact sedan was as high as 25-27% at higher speeds, where the aerodynamic drag is most pronounced. For both vehicles, use of a hitch mounted cargo tray carrying a similar load resulted in very small FE penalties, unlike the rooftop cargo box. The results for the SUV pulling a 3500 pound enclosed cargo trailer were rather dramatic, resulting in FE penalties ranging from 30%, for the city cycle, to 50% at 80 mph, at which point significant CO generation indicated protective enrichment due to high load. Low tire pressure cases resulted in negligible to 10% FE penalty depending on the specific case and test point. Driving with all four windows open decreased FE by 4-8.5% for the compact sedan, and 1-4% for the SUV.

fuel economy↗

DOE OSTI2025

Window observables for benchmarking parton distribution functions

Global analysis of collider and fixed-target experimental data and calculations from lattice quantum chromodynamics (QCD) are used to gain complementary information on the structure of hadrons. We propose novel ``window observables'' that allow for higher precision cross-validation between the different approaches, a critical step for studies that wish to combine the datasets. Global analyses are limited by the kinematic regions accessible to experiment, particularly in a range of Bjorken-x, and lattice QCD calculations also have limitations requiring extrapolations to obtain the parton distributions. We provide two different ``window observables'' that can be defined within a region of x where extrapolations and interpolations in global analyses remain reliable and where lattice QCD results retain sensitivity and precision.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1970

Radiant heating concept efficient for light-transmitting windows

Single-pane, uncoated windows absorb infrared rays and transmit visible and near-visible wavelengths. Two opposed rod heaters direct infrared rays at the pane, reflectors aid in this heating which prevents condensation. These windows are useful for telescopes and cameras for oceanographic and related studies.

Neuman, J. R.↗