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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Testing the Jump Finding Code for NEXUS Qubit Analysis

At Fermilab, the NEXUS dilution refrigerator is repeating the same experiment from Wilen et al. 1 underground to further investigate the effect of ionizing radiation and cosmic ray muons on qubit decoherence. This refrigerator is 100m underground in the MINOS cavern to significantly lower the incident rate of cosmic ray muons, meaning the majority of incidents is due to ionizing radiation. To gain a better understanding of how the rate of ionizing radiation affects the qubits, we use 4 radiation configurations to collect data from the chip. In this work, we examine the efficiency of our jump detection code to find jumps of various sizes. We do so using simulated data with a known number of injected jumps of known sizes. These jumps are charge offsets of the qubit, thought to be due to quasiparticle poisoning. To test this, we run the jump finding code on an array of simulated data in which two main parameters, the smoothing factor and the threshold at which a charge offset is considered a jump, are changed to test an array of these parameters. We then perform a χ2 analysis to find the best combination of these two parameters.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Genetic algorithms applied to reconstructing coded imaging of neutrons and analysis of residual watermark

Monte-Carlo simulation of neutron coded imaging based on encoding aperture for Z-pinch of large field-of-view with 5 mm radius has been investigated, and then the coded image has been obtained. Reconstruction method of source image based on genetic algorithms (GA) has been established. 'Residual watermark,' which emerges unavoidably in reconstructed image, while the peak normalization is employed in GA fitness calculation because of its statistical fluctuation amplification, has been discovered and studied. Residual watermark is primarily related to the shape and other parameters of the encoding aperture cross section. The properties and essential causes of the residual watermark were analyzed, while the identification on equivalent radius of aperture was provided. By using the equivalent radius, the reconstruction can also be accomplished without knowing the point spread function (PSF) of actual aperture. The reconstruction result is close to that by using PSF of the actual aperture.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

A Validation and Code-to-Code Verification of FAST for a Megawatt-Scale Wind Turbine with Aeroelastically Tailored Blades

This paper presents validation and code-to-code verification of the latest version of the U.S. Department of Energy, National Renewable Energy Laboratory wind turbine aeroelastic engineering simulation tool, FAST v8. A set of 1,141 test cases, for which experimental data from a Siemens 2.3 MW machine have been made available and were in accordance with the International Electrotechnical Commission 61400-13 guidelines, were identified. These conditions were simulated using FAST as well as the Siemens in-house aeroelastic code, BHawC. This paper presents a detailed analysis comparing results from FAST with those from BHawC as well as experimental measurements, using statistics including the means and the standard deviations along with the power spectral densities of select turbine parameters and loads. Results indicate a good agreement among the predictions using FAST, BHawC, and experimental measurements. Here, these agreements are discussed in detail in this paper, along with some comments regarding the differences seen in these comparisons relative to the inherent uncertainties in such a model-based analysis.

17 WIND ENERGY↗
DOE OSTI2014

RAVEN, a New Software for Dynamic Risk Analysis

RAVEN is a generic software driver to perform parametric and probabilistic analysis of code simulating complex systems. Initially developed to provide dynamic risk analysis capabilities to the RELAP-7 code [1] is currently being generalized with the addition of Application Programming Interfaces (APIs). These interfaces are used to extend RAVEN capabilities to any software as long as all the parameters that need to be perturbed are accessible by inputs files or directly via python interfaces. RAVEN is capable to investigate the system response probing the input space using Monte Carlo, grid strategies, or Latin Hyper Cube schemes, but its strength is its focus toward system feature discovery like limit surfaces separating regions of the input space leading to system failure using dynamic supervised learning techniques. The paper will present an overview of the software capabilities and their implementation schemes followed by same application examples.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

In-Depth Analysis of Simulation Engine Codes for Comparison with DOE's Roof Savings Calculator and Measured Data

The Roof Savings Calculator (RSC) was developed through collaborations among Oak Ridge National Laboratory (ORNL), White Box Technologies, Lawrence Berkeley National Laboratory (LBNL), and the Environmental Protection Agency in the context of a California Energy Commission Public Interest Energy Research project to make cool-color roofing materials a market reality. The RSC website and a simulation engine validated against demonstration homes were developed to replace the liberal DOE Cool Roof Calculator and the conservative EPA Energy Star Roofing Calculator, which reported different roof savings estimates. A preliminary analysis arrived at a tentative explanation for why RSC results differed from previous LBNL studies and provided guidance for future analysis in the comparison of four simulation programs (doe2attic, DOE-2.1E, EnergyPlus, and MicroPas), including heat exchange between the attic surfaces (principally the roof and ceiling) and the resulting heat flows through the ceiling to the building below. The results were consolidated in an ORNL technical report, ORNL/TM-2013/501. This report is an in-depth inter-comparison of four programs with detailed measured data from an experimental facility operated by ORNL in South Carolina in which different segments of the attic had different roof and attic systems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

Steps towards verification and validation of the Fetch code for Level 2 analysis, design, and optimization of aqueous homogeneous reactors

Babcock and Wilcox Technical Services Group (B and W) has identified aqueous homogeneous reactors (AHRs) as a technology well suited to produce the medical isotope molybdenum 99 (Mo-99). AHRs have never been specifically designed or built for this specialized purpose. However, AHRs have a proven history of being safe research reactors. In fact, in 1958, AHRs had 'a longer history of operation than any other type of research reactor using enriched fuel' and had 'experimentally demonstrated to be among the safest of all various type of research reactor now in use [1].' While AHRs have been modeled effectively using simplified 'Level 1' tools, the complex interactions between fluids, neutronics, and solid structures are important (but not necessarily safety significant). These interactions require a 'Level 2' modeling tool. Imperial College London (ICL) has developed such a tool: Finite Element Transient Criticality (FETCH). FETCH couples the radiation transport code EVENT with the computational fluid dynamics code (Fluidity), the result is a code capable of modeling sub-critical, critical, and super-critical solutions in both two-and three-dimensions. Using FETCH, ICL researchers and B and W engineers have studied many fissioning solution systems include the Tokaimura criticality accident, the Y12 accident, SILENE, TRACY, and SUPO. These modeling efforts will ultimately be incorporated into FETCH'S extensive automated verification and validation (V and V) test suite expanding FETCH'S area of applicability to include all relevant physics associated with AHRs. These efforts parallel B and W's engineering effort to design and optimize an AHR to produce Mo99. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2017

Design Analysis of SNS Target StationBiological Shielding Monoligh with Proton Power Uprate

This report documents the analysis of the dose rate in the experiment area outside the Spallation Neutron Source (SNS) target station shielding monolith with proton beam energy of 1.3 GeV. The analysis implemented a coupled three dimensional (3D)/two dimensional (2D) approach that used both the Monte Carlo N-Particle Extended (MCNPX) 3D Monte Carlo code and the Discrete Ordinates Transport (DORT) two dimensional deterministic code. The analysis with proton beam energy of 1.3 GeV showed that the dose rate in continuously occupied areas on the lateral surface outside the SNS target station shielding monolith is less than 0.25 mrem/h, which complies with the SNS facility design objective. However, the methods and codes used in this analysis are out of date and unsupported, and the 2D approximation of the target shielding monolith does not accurately represent the geometry. We recommend that this analysis is updated with modern codes and libraries such as ADVANTG or SHIFT. These codes have demonstrated very high efficiency in performing full 3D radiation shielding analyses of similar and even more difficult problems.

42 ENGINEERING↗
DOE OSTI2017

Sensitivity Studies of the Inter-subchannel Mixing in Subchannel Analysis

In the PWR reactor core, the power profile is nonuniform and the inter-subchannel mixing is of great importance for flatting the temperature distribution of the coolant and for reactor core safety analysis. Subchannel codes are widely used in the reactor core safety analysis to assess the thermal hydraulic behavior of fuel assemblies. One of basic assumptions in subchannel analysis is that axial flow predominates in the channel flow. Under this assumption, the lateral momentum equation in subchannel codes can be simplified without bringing in significant errors. The inter-subchannel mixing leading to the exchange of mass, energy and momentum are modeled by adding source terms to the hydrodynamic equations or by separate models, and most of source terms and models are empirical correlations. With the advancement of mixing vane grid design, the lateral mixing has becoming a critical components in the evaluation of the inter-subchannel mixing in flow field. The accuracy of the subchannel analysis is strongly dependent on the modeling of inter-subchannel interactions between adjacent subchannels. So the inter-subchannel mixing models should be well considered and developed in subchannel analysis to better reflect their influence on flow field and temperature field in rod bundle. Generally speaking, the inter-subchannel mixing in subchannel analysis contains turbulent mixing and crossflow mixing in single phase flow. When it comes to two phase flow, the void drift will also contribute to inter-subchannel mixing [2]. Both the mechanisms and the generation conditions of each type of inter-subchannel mixing are different from each other. Turbulent mixing is a result of random turbulent flow and pressure fluctuations. Crossflow is caused by a net transverse pressure difference between adjacent subchannels. Lateral pressure differences can result from different subchannel hydraulic diameters, mass flux, heat flux distributions and changes in flow areas caused, for example, by wire wraps and spacer grids, respectively. Two-phase void drift is due to the tendency of the vapor phase to redistribute itself to a preferred equilibrium void distribution. This paper focuses on the sensitivity study of the inter-subchannel mixing with mixing vane grids for single phase flow in subchannel analysis. Both the turbulent mixing and crossflow mixing of the 5 x 5 rod bundle with mixing vane grids are predicted, and the results are compared and analyzed.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Binary Analysis with Architecture and Code Section Detection using Supervised Machine Learning

When presented with an unknown binary, which may or may not be complete, having the ability to determine information about it is critical to future reverse engineering, particularly in discovering the binary’s intended use and potentially malicious nature. This paper details techniques to both identify the machine architecture of the binary, as well as to locate the important code segments within the file. This identification of unknown binaries makes use of a technique called byte histogram in addition to various machine learning (ML) techniques, which we call “What is it Binary” or WiiBin. Benefits of byte histograms reflect the simplicity of calculation and do not rely on file headers or metadata, allowing for acceptable results when only a small portion of the original file is available. Utilizing WiiBin, we were able to accurately (>80%) determine the architecture of test binaries with as little as a 20% contagious portion of the file present. We were also able to determine the location of code sections within a binary by utilizing the WiiBin framework. Ultimately, the more information that can be gleaned from a binary file, the easier it is to successfully reverse engineer.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2012

Reevaluation of the Coding Potential and Proteomic Analysis of the BAC Derived Rhesus Cytomegalovirus Strain 68-1

Cytomegaloviruses are highly host restricted resulting in co-speciation with their hosts. As a natural pathogen of rhesus macaques (RM), Rhesus Cytomegalovirus (RhCMV) has therefore emerged as a highly relevant experimental model for pathogenesis and vaccine development due to its close evolutionary relationship to human CMV (HCMV). To date, most in vivo experiments performed with RhCMV employed strain 68-1 cloned as bacterial artificial chromosome (BAC). However, the complete genome sequence of the 68-1 BAC has not been determined. Furthermore, the gene content of the RhCMV genome is unknown and previous open reading frame (ORF) predictions relied solely on uninterrupted ORFs with an arbitrary cutoff of 300bp. To obtain a more precise picture of the actual proteins encoded by the most commonly used molecular clone of RhCMV we re-evaluated the RhCMV 68-1 BAC-genome by whole genome shotgun sequencing and determined the protein content of the resulting RhCMV virions by proteomics. By additionally comparing the RhCMV genome to that of several closely related Old World Monkey (OWM) CMVs we were able to filter out many unlikely ORFs and obtain a simplified map of the RhCMV genome. This comparative genomics analysis eliminated many genes previously characterized as RhCMV-specific while consolidating a high conservation of ORFs among OWM-CMVs and between RhCMV and HCMV. Moreover, virion proteomics independently validated the revised ORF predictions since only proteins encoded by predicted ORFs could be detected. Taken together these data suggest a much higher conservation of genome and virion structure between CMVs of humans, apes and OWMs than previously assumed. Remarkably, BAC-derived RhCMV is able to establish and maintain persistent infection despite the lack of multiple genes homologous to HCMV genes involved in tissue tropism.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2017

Tri-Lab Co-Design Milestone: In-Depth Performance Portability Analysis of Improved Integrated Codes on Advanced Architecture.

This milestone is a tri-lab deliverable supporting ongoing Co-Design efforts impacting applications in the Integrated Codes (IC) program element Advanced Technology Development and Mitigation (ATDM) program element. In FY14, the trilabs looked at porting proxy application to technologies of interest for ATS procurements. In FY15, a milestone was completed evaluating proxy applications in multiple programming models and in FY16, a milestone was completed focusing on the migration of lessons learned back into production code development. This year, the co-design milestone focuses on extracting the knowledge gained and/or code revisions back into production applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2012

An Analysis of Building Energy Code Statewide Adoption Rates by Local Jurisdiction

The purpose of this study is to quantify the energy code adoption rate by local jurisdictions from a sample set of 21 states. Some of the states within this sample have statewide energy codes, while others do not. Using construction starts and weighting results by localities that have or have not adopted energy codes, the findings can suggest a means of identifying which states have “effectively” adopted statewide codes through local adoption and enforcement.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2021

A Case Study of LLVM-Based Analysis for Optimizing SIMD Code Generation

This paper presents a methodology for using LLVM-based tools to tune the DCA++ (dynamical cluster approximation) application that targets the new ARM A64FX processor. The goal is to describe the changes required for the new architecture and generate efficient single instruction/multiple data (SIMD) instructions that target the new Scalable Vector Extension instruction set. During manual tuning, the authors used the LLVM tools to improve code parallelization by using OpenMP SIMD, refactored the code and applied transformation that enabled SIMD optimizations, and ensured that the correct libraries were used to achieve optimal performance. By applying these code changes, code speed was increased by 1.98× and 78 GFlops were achieved on the A64FX processor. The authors aim to automatize parts of the efforts in the OpenMP Advisor tool, which is built on top of existing and newly introduced LLVM tooling.

Huber, Joseph↗