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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

An empirical comparison of software fault tolerance and fault elimination

Reliability is an important concern in the development of software for modern systems. Some researchers have hypothesized that particular fault-handling approaches or techniques are so effective that other approaches or techniques are superfluous. The authors have performed a study that compares two major approaches to the improvement of software, software fault elimination and software fault tolerance, by examination of the fault detection obtained by five techniques: run-time assertions, multi-version voting, functional testing augmented by structural testing, code reading by stepwise abstraction, and static data-flow analysis. This study has focused on characterizing the sets of faults detected by the techniques and on characterizing the relationships between these sets of faults. The results of the study show that none of the techniques studied is necessarily redundant to any combination of the others. Further results reveal strengths and weakness in the fault detection by the techniques studied and suggest directions for future research.

Shimeall, Timothy J.↗
DOE OSTI2023

Rovibronic molecular line list for the $N_2(C^3Π_u–B^3Π_g)$ second positive system

Here, a line list for the N second positive system, $B^3Π_g—C^3Π_u$, has been compiled using the PGOPHER spectral simulation software. The line list extends the number of vibrational states of the $B^3Π_g$ up to v=29 and a maximum rotational state of J=150 for simulation temperatures up to 7000 K. New electronic–vibrational transition moments were calculated using refined potential energy curves and a transition dipole moment with the DUO software. Comparisons to experimental data and the SPECAIR software have been used to validate the new line list. The results are available in ASCII ExoMol .state and .trans files and as a PGOPHER input file for use in spectral analysis.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2010

NASA Tech Briefs, June 2010

Topics covered include: Situational Awareness from a Low-Cost Camera System; Data Acquisition System for Multi-Frequency Radar Flight Operations Preparation; Mercury Toolset for Spatiotemporal Metadata; Social Tagging of Mission Data; Integrating Radar Image Data with Google Maps; Demonstration of a Submillimeter-Wave HEMT Oscillator Module at 330 GHz; Flexible Peripheral Component Interconnect Input/Output Card; Interface Supports Lightweight Subsystem Routing for Flight Applications; MMIC Amplifiers and Wafer Probes for 350 to 500 GHz; Public Risk Assessment Program; Particle Swarm Optimization Toolbox; Telescience Support Center Data System Software; Update on PISCES; Ground and Space Radar Volume Matching and Comparison Software; Web-Based Interface for Command and Control of Network Sensors; Orbit Determination Toolbox; Distributed Observer Network; Computer-Automated Evolution of Spacecraft X-Band Antennas; Practical Loop-Shaping Design of Feedback Control Systems; Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate; Formula for the Removal and Remediation of Polychlorinated Biphenyls in Painted Structures; Integrated Solar Concentrator and Shielded Radiator; Water Membrane Evaporator; Modeling of Failure for Analysis of Triaxial Braided Carbon Fiber Composites; Catalyst for Carbon Monoxide Oxidation; Titanium Hydroxide - a Volatile Species at High Temperature; Selective Functionalization of Carbon Nanotubes: Part II; Steerable Hopping Six-Legged Robot; Launchable and Retrievable Tetherobot; Hybrid Heat Exchangers; Orbital Winch for High-Strength, Space-Survivable Tethers; Parameterized Linear Longitudinal Airship Model; and Physics of Life: A Model for Non-Newtonian Properties of Living Systems.

Source record↗
DOE OSTI2024

Stereo-DIC Challenge 1.0 – Rigid Body Motion of a Complex Shape

Background Stereo-DIC is a widely used optical measurement technique that provides a dense full-field 3D measurement of the shape, displacement, and strain of a solid sample. When compared with 2D-DIC, Stereo-DIC provides greater flexibility and expands its use beyond flat, planar specimens. Furthermore, the widespread availability of commercial systems has led to the adoption of the technique throughout industry, academia, and government research labs. Objective Even though some research has been done to understand the effects of different experimental and stereo-DIC parameters, no reference is available to benchmark and compare the performance of current stereo-DIC algorithms to each other. Methods This paper provides the description and analysis of a carefully controlled 3D experiment and associated images used to compare the results from five subset based DIC software packages. Both the images and analysis codes used in this paper to compare the results are described here and are available for download and use for continued research. Results We show that over a very large range of motion, the 3D errors are very small, less than 80μm over a travel of ±20 mm out-of-plane and ±20 mm in-plane. While all codes performed similarly, there are important differences noted in the paper. Conclusion The image sets and results comparison software are hosted by the International DIC Society (www.iDICs.org) and are freely available for download and analysis for comparison with results in this paper. Furthermore, it is hoped that this set of images can be used for future research in improving stereo-DIC by future authors.

Algorithms comparison↗
DOE OSTI2014

SU-E-J-26: Analysis of Image Quality in CBCT QA Using a Treatment Planning System

Purpose: The objective of this study is to propose an alternative QA technique that analyzes imaging quality(IQ) in CBCT-QA processing. Methods: A catphan phantom was used to take CT imaging data set that were imported into a treatment planning system - Eclipse. The image quality was analyzed in terms of in-slice geometry resolution, Hounsfield numbers(HU) accuracy, mean-slice thickness, edge-to-center uniformity, low contrast resolution, and high contrast spatial resolution in Eclipse workstation. The CBCT-QA was also analyzed by OBI-workstation and a commercial software. Comparison was made to evaluation feasibility in a TPS environment. Results: The analysis of IQ was conducted in Eclipse v10.0 TPS. In-slice geometric resolution was measured between 2-rods in section CTP404 and repeated for all 4 rods with the difference between expected and measured values less than +/−0.1 cm. For HU, the difference between expected and measured values in HU was found much less than +/−40. Mean slice thickness measured by a distance on the wire proportional to scanner increment multiplying by a factor of 0.42. After repeating measurements to 4 wires, the average difference between expected and measured values was less +/−0.124 mm in slice thickness. HU uniformity was measured in section CTP486 with the tolerance less than +/−40 HU. Low contrast resolution in section CTP515 and high contrast resolution in section CTP528 were found to be 7 disks in diameter of 4 mm and 6 lp/cm, respectively. Eclipse TPS results indicated a good agreement to those obtained in OBI workstation and ImagePro software for major parameters. Conclusion: An analysis of IQ was proposed as an alternative CBCT QA processing. Based upon measured data assessment, proposed method was accurate and consistent to IQ evaluation and TG142 guideline. The approach was to utilize TPS resource, which can be valuable to re-planning, verification, and delivery in adaptive therapy.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Nonlinear Interface Reduction for Time-Domain Analysis of Hurty/Craig-Bampton Superelements with Frictional Contact

Virtual prototyping in engineering design relies today on modern numerical models of contacting structures with accurate resolution of interface mechanics, which strongly affect the system-level stiffness and energy dissipation due to frictional losses. High-fidelity modeling within the localized interfaces is required to resolve local quantities of interest that may drive design decisions. The high-resolution finite element meshes necessary to resolve inter-component stresses tend to be computationally expensive, particularly when the analyst is interested in response time histories. The Hurty/Craig-Bampton (HCB) transformation is a widely used method in structural dynamics for reducing the interior portion of a finite element model while having the ability to retain all nonlinear contact degrees of freedom (DOF) in physical coordinates. These models may still require many DOF to adequately resolve the kinematics of the interface, leading to inadequate reduction and computational savings. This study proposes a novel interface reduction method to overcome these challenges by means of system-level characteristic constraint (SCC) modes and properly orthogonal interface modal derivatives (POIMDs) for transient dynamic analyses. Both SCC modes and POIMDs are computed using the reduced HCB mass and stiffness matrices, which can be directly computed from many commercial finite element analysis software. Comparison of time history responses to an impulse-type load in a mechanical beam assembly indicate that the interface-reduced model correlates well with the HCB truth model. Localized features like slip and contact area are well-represented in the time domain when the beam assembly is loaded with a broadband excitation. The proposed method also yields reduced-order models with greater critical timestep lengths for explicit integration schemes.

42 ENGINEERING↗
DOE OSTI2015

SU-E-T-83: A Study On Evaluating the Directional Dependency of 2D Seven 29 Ion Chamber Array Clinically with Different IMRT Plans

Purpose: To evaluate the directional dependency of 2D seven 29 ion chamber array clinically with different IMRT plans. Methods: 25 patients already treated with IMRT plans were selected for the study. Verification plans were created for each treatment plan in eclipse 10 treatment planning system using the AAA algorithm with the 2D array and the Octavius CT phantom. Verification plans were done 2 times for a single patient. First plan with real IMRT (plan-related approach) and second plan with zero degree gantry angle (field-related approach). Measurements were performed on a Varian Clinac-iX, linear accelerator equipped with a millennium 120 multileaf collimator. Fluence was measured for all the delivered plans and analyzed using the verisoft software. Comparison was done by selecting the fluence delivered in static gantry (zero degree gantry) versus IMRT with real gantry angles. Results: The gamma pass percentage is greater than 97 % for all IMRT delivered with zero gantry angle and between 95%–98% for real gantry angles. Dose difference between the TPS calculated and measured for IMRT delivered with zero gantry angle was found to be between (0.03 to 0.06Gy) and with real gantry angles between (0.02 to 0.05Gy). There is a significant difference between the gamma analysis between the zero degree and true angle with a significance of 0.002. Standard deviation of gamma pass percentage between the IMRT plans with zero gantry angle was 0.68 and for IMRT with true gantry angle was found to be 0.74. Conclusion: The gamma analysis for IMRT with zero degree gantry angles shows higher pass percentage than IMRT delivered with true gantry angles. Verification plans delivered with true gantry angles lower the verification accuracy when 2D array is used for measurement.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1992

Convective flow analysis on the KC-135 aircraft

A study conducting bouyancy driven convective flow experiments on the NASA KC-135 aircraft is presented. The response of a contained fluid (with an imposed temperature gradient) to changing g-levels during parabolic flight was obtained. Models for both transient and steady state flows were developed utilizing PC-based CFD software. Comparisons between the theoretical models and the physical observations are quite good.

Workman, Gary L.↗
NASA NTRS2004

Semi-Empirical Modeling of SLD Physics

The effects of supercooled large droplets (SLD) in icing have been an area of much interest in recent years. As part of this effort, the assumptions used for ice accretion software have been reviewed. A literature search was performed to determine advances from other areas of research that could be readily incorporated. Experimental data in the SLD regime was also analyzed. A semi-empirical computational model is presented which incorporates first order physical effects of large droplet phenomena into icing software. This model has been added to the LEWICE software. Comparisons are then made to SLD experimental data that has been collected to date. Results will be presented for the comparison of water collection efficiency, ice shape and ice mass.

Wright, William B.↗
NASA NTRS2011

Super Cooled Large Droplet Analysis of Several Geometries Using LEWICE3D Version 3

Super Cooled Large Droplet (SLD) collection efficiency calculations were performed for several geometries using the LEWICE3D Version 3 software. The computations were performed using the NASA Glenn Research Center SLD splashing model which has been incorporated into the LEWICE3D Version 3 software. Comparisons to experiment were made where available. The geometries included two straight wings, a swept 64A008 wing tip, two high lift geometries, and the generic commercial transport DLR-F4 wing body configuration. In general the LEWICE3D Version 3 computations compared well with the 2D LEWICE 3.2.2 results and with experimental data where available.

Bidwell, Colin S.↗
DOE OSTI2015

Comparison of Deposition© software predictions to published experimental results for large (152 mm by 152 mm) square ducts

A comparison was performed between experimental aerosol deposition measurements in large air ducts, compared to predictions performed by the US Nuclear Regulatory Commission Deposition© software package. Although the Deposition© code was designed to calculate the transport of radioactive aerosols in small diameter sampling tubes, it was not certain that the software would adequately predict aerosol transport in large air ducts. Two sets of experimental data were used in this comparison, one set of results from small diameter (1.27 mm ID) tubes, and the other data set was from testing on large diameter (152 mm square) ventilation ducts. In general, the Deposition© software performs excellent predictions if the ductwork system has a computed aerosol percent penetration greater than 75% (with a 2.9% average error compared to experiments). For example, shorter duct systems have higher aerosol penetrations than a longer duct system of the same diameter. However, when the Deposition© software calculated an aerosol penetration less than about 75% for a particular duct system, the average percent error increased to 68.3% when compared to experimental measurements. The Deposition© software could therefore be used to ensure that an aerosol would have a high percent penetration through a ductwork system, but it should not be used to make (dosimetric) decisions about ductwork performance if the calculated percent penetration is less than 75%. This document includes a section of attached engineering formulas that explain the structure of the Excel spreadsheet calculations.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1992

Advanced software development workstation. Comparison of two object-oriented development methodologies

This report is an attempt to clarify some of the concerns raised about the OMT method, specifically that OMT is weaker than the Booch method in a few key areas. This interim report specifically addresses the following issues: (1) is OMT object-oriented or only data-driven?; (2) can OMT be used as a front-end to implementation in C++?; (3) the inheritance concept in OMT is in contradiction with the 'pure and real' inheritance concept found in object-oriented (OO) design; (4) low support for software life-cycle issues, for project and risk management; (5) uselessness of functional modeling for the ROSE project; and (6) problems with event-driven and simulation systems. The conclusion of this report is that both Booch's method and Rumbaugh's method are good OO methods, each with strengths and weaknesses in different areas of the development process.

Izygon, Michel E.↗
DOE OSTI2019

Comparison of two software systems for quantification of myocardial blood flow in patients with hypertrophic cardiomyopathy

Backgorund: Quantification of myocardial blood flow (MBF) by positron emission tomography (PET) is important for investigation of angina in hypertrophic cardiomyopathy (HCM). Several software programs exist for MBF quantification, but they have been mostly evaluated in patients (with normal cardiac geometry), referred for evaluation of coronary artery disease (CAD). Software performance has not been evaluated in HCM patients who frequently have hyperdynamic LV function, LV outflow tract (LVOT) obstruction, small LV cavity size, and variation in the degree/location of LV hypertrophy. Aim: We compared results of MBF obtained using PMod, which permits manual segmentation, to those obtained by FDA-approved QPET software which has an automated segmentation algorithm. Methods: {sup 13}N-ammonia PET perfusion data were acquired in list mode at rest and during pharmacologic vasodilation, in 76 HCM patients and 10 non-HCM patients referred for evaluation of CAD (CAD group.) Data were resampled to create static, ECG-gated and 36-frame-dynamic images. Myocardial flow reserve (MFR) and MBF (in ml/min/g) were calculated using QPET and PMod softwares. Results: All HCM patients had asymmetric septal hypertrophy, and 50% had evidence of LVOT obstruction, whereas non-HCM patients (CAD group) had normal wall thickness and ejection fraction. PMod yielded significantly higher values for global and regional stress-MBF and MFR than for QPET in HCM. Reasonably fair correlation was observed for global rest-MBF, stress-MBF, and MFR using these two softwares (rest-MBF: r = 0.78; stress-MBF: r = 0.66.; MFR: r = 0.7) in HCM patients. Agreement between global MBF and MFR values improved when HCM patients with high spillover fractions (> 0.65) were excluded from the analysis (rest-MBF: r = 0.84; stress-MBF: r = 0.72; MFR: r = 0.8.) Regionally, the highest agreement between PMod and QPET was observed in the LAD territory (rest-MBF: r = 0.82, Stress-MBF: r = 0.68) where spillover fraction was the lowest. Unlike HCM patients, the non-HCM patients (CAD group) demonstrated excellent agreement in MBF/MFR values, obtained by the two softwares, when patients with high spillover fractions were excluded (rest-MBF: r = 0.95; stress-MBF: r = 0.92; MFR: r = 0.95). Conclusions: Anatomic characteristics specific to HCM hearts contribute to lower correlations between MBF/MFR values obtained by PMod and QPET, compared with non-HCM patients. These differences indicate that PMod and QPET cannot be used interchangeably for MBF/MFR analyses in HCM patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2014

RotCFD Software Validation - Computational and Experimental Data Comparison

RotCFD is a software intended to ease the design of NextGen rotorcraft. Since RotCFD is a new software still in the development process, the results need to be validated to determine the software's accuracy. The purpose of the present document is to explain one of the approaches to accomplish that goal.

Experimental Data Comparison↗