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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Development of an emulation-simulation thermal control model for space station application

Many features were added to the Thermal Control System (TCS) program to increase its user-friendliness. Several apparent inconsistencies were identified. In some instances, these have led to modifications to the source programs. With the summary line-sizing information, the user can more readily compare the TCS program results with other available data. Two mathematical models were completed: one deals with sizing and analysis of bus heat exchangers and the other provides a means of analyzing a variety of heat pipe radiator designs. A generic heat pipe model was added to the TCS Analysis Program.

Colwell, Gene T.↗
NASA NTRS1989

MHOST version 4.2. Volume 1: Users' manual

This manual describes the user options available for running the MHOST finite element analysis package. MHOST is a solid and structural analysis program based on mixed finite element technology, and is specifically designed for three-dimensional inelastic analysis. A family of two- and three-dimensional continuum elements along with beam and shell structural elements can be utilized. Many options are available in the constitutive equation library, the solution algorithms and the analysis capabilities. An overview of the algorithms, a general description of the input data formats, and a discussion of input data for selecting solution algorithms are given.

Nakazawa, Shohei↗
NASA NTRS1993

Impact of shorter wavelengths on optical quality for laws

This study explores parametrically as a function of wavelength the degrading effects of several common optical aberrations (defocus, astigmatism, wavefronttilts, etc.), using the heterodyne mixing efficiency factor as the merit function. A 60 cm diameter aperture beam expander with an expansion ratio of 15:1 and a primary mirror focal ratio of f/2 was designed for the study. An HDOS copyrighted analysis program determined the value of merit function for various optical misalignments. With sensitivities provided by the analysis, preliminary error budget and tolerance allocations were made for potential optical wavefront errors and boresight errors during laser shot transit time. These were compared with the baseline 1.5 m CO2 laws and the optical fabrication state of the art (SOA) as characterized by the Hubble Space Telescope. Reducing wavelength and changing optical design resulted in optical quality tolerances within the SOA both at 2 and 1 micrometer. However, advanced sensing and control devices would be necessary to be tightened by a factory of 1.8 for a 2 micrometer system and by 3.6 for a 1 micrometer system relative to the baseline CO2 LAWS. Available SOA components could be used for operation at 2 micrometers but operation at 1 micrometer does not appear feasible.

Wissinger, Alan B.↗
NASA NTRS1993

Impact of shorter wavelengths on optical quality for laws

This study explores parametrically as a function of wavelength the degrading effects of several common optical aberrations (defocus, astigmatism, wavefront tilts, etc.), using the heterodyne mixing efficiency factor as the merit function. A 60 cm diameter aperture beam expander with an expansion ratio of 15:1 and a primary mirror focal ratio of f/2 was designed for the study. An HDOS copyrighted analysis program determined the value of merit function for various optical misalignments. With sensitivities provided by the analysis, preliminary error budget and tolerance allocations were made for potential optical wavefront errors and boresight errors during laser shot transit time. These were compared with the baseline l.5 m CO2 LAWS and the optical fabrication state of the art (SOA) as characterized by the Hubble Space Telescope. Reducing wavelength and changing optical design resulted in optical quality tolerances within the SOA both at 2 and 1 micrometers. However, advanced sensing and control devices would be necessary to maintain on-orbit alignment. Optical tolerance for maintaining boresight stability would have to be tightened by a factor of 1.8 for a 2 micrometers system and by 3.6 for a 1 micrometers system relative to the baseline CO2 LAWS. Available SOA components could be used for operation at 2 micrometers but operation at 1 micrometers does not appear feasible.

Wissinger, Alan B.↗
NASA NTRS2001

Development Cycle Time Simulation for Civil Aircraft

Cycle Time Reduction (CTR) will be one of the major factors affecting the future of the civil aerospace industry. This focus is the end reflection of the level of competition in the commercial large carrier aircraft industry. Aircraft manufacturer must minimize costs and pass a portion of those savings onto buyers. CTR is one strategy used to move the manufacturing firm down the cost curve. The current NASA Airframe Development Cycle Time Reduction Goal is 50% by year 2022. This goal is not achievable based on the program analysis done by the LMI/GRA team. This may mean that the current roster of NASA CTR programs needs to be reexamined or that the program technology progress factors, as determined by the NASA experts, were understated. Programs that duplicate the reductions of others should be replaced with non-duplicative programs. In addition, new programs targeting a specific part of the cycle can be developed.

Spitz, William↗
NASA NTRS2002

Propulsion System Modeling and Simulation

The Aerospace Systems Design Laboratory at the School of Aerospace Engineering in Georgia Institute of Technology has developed a core competency that enables propulsion technology managers to make technology investment decisions substantiated by propulsion and airframe technology system studies. This method assists the designer/manager in selecting appropriate technology concepts while accounting for the presence of risk and uncertainty as well as interactions between disciplines. This capability is incorporated into a single design simulation system that is described in this paper. This propulsion system design environment is created with a commercially available software called iSIGHT, which is a generic computational framework, and with analysis programs for engine cycle, engine flowpath, mission, and economic analyses. iSIGHT is used to integrate these analysis tools within a single computer platform and facilitate information transfer amongst the various codes. The resulting modeling and simulation (M&S) environment in conjunction with the response surface method provides the designer/decision-maker an analytical means to examine the entire design space from either a subsystem and/or system perspective. The results of this paper will enable managers to analytically play what-if games to gain insight in to the benefits (and/or degradation) of changing engine cycle design parameters. Furthermore, the propulsion design space will be explored probabilistically to show the feasibility and viability of the propulsion system integrated with a vehicle.

Tai, Jimmy C. M.↗
DOE OSTI2022

INL Contributions to Draft HTTF Benchmark Specifications

The High-Temperature Test Facility (HTTF) is an integral effects thermal hydraulics test facility at Oregon State University designed as a 1/4 length scale model of the Modular High-Temperature Gas-Cooled Reactor 350 MW core (mHTGR-350). In the spring and summer of 2019, several experiments were conducted at HTTF providing a valuable source of gas-cooled reactor thermal hydraulics data. Idaho National Laboratory (INL), Oregon State University, Argonne National Laboratory, and Canadian Nuclear Laboratories have partnered to use this experimental data to develop a gas-cooled reactor thermal hydraulics benchmark led by INL under the auspices of the Advanced Reactor Technologies (ART) program. This report provides some context on the benchmark, HTTF, and previous Reactor Excursions and Leak Analysis Program (RELAP)5-3D modeling of HTTF. It also provides a draft of the benchmark specifications for the Depressurized Conduction Cooldown problem, which is the INL-led benchmark problem.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Exploring Explicit Uncertainty for Binary Analysis (EUBA)

Reverse engineering (RE) analysts struggle to address critical questions about the safety of binary code accurately and promptly, and their supporting program analysis tools are simply wrong sometimes. The analysis tools have to approximate in order to provide any information at all, but this means that they introduce uncertainty into their results. And those uncertainties chain from analysis to analysis. We hypothesize that exposing sources, impacts, and control of uncertainty to human binary analysts will allow the analysts to approach their hardest problems with high-powered analytic techniques that they know when to trust. Combining expertise in binary analysis algorithms, human cognition, uncertainty quantification, verification and validation, and visualization, we pursue research that should benefit binary software analysis efforts across the board. We find a strong analogy between RE and exploratory data analysis (EDA); we begin to characterize sources and types of uncertainty found in practice in RE (both in the process and in supporting analyses); we explore a domain-specific focus on uncertainty in pointer analysis, showing that more precise models do help analysts answer small information flow questions faster and more accurately; and we test a general population with domain-general sudoku problems, showing that adding "knobs" to an analysis does not significantly slow down performance. This document describes our explorations in uncertainty in binary analysis.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1977

Validation of a Flexible Aircraft TakeOff and Landing Analysis /FATOLA/ computer program using flight landing data

A multiple-degree-of-freedom takeoff and landing analysis, Flexible Aircraft TakeOff and Landing Analysis computer program (FATOLA), was used to predict the landing behavior of a rigid-body X-24B reentry research vehicle and of a flexible-body modified-delta-wing supersonic YF-12 research aircraft. The analytical predictions were compared with flight test data for both research vehicles. Predicted time histories of vehicle motion and attitude, landing-gear strut stroke, and axial force transmitted from the landing gear to the airframe during the landing impact and rollout compared well with the actual time histories. Based on the comparisons presented, the versatility and validity of the FATOLA program for predicting landing dynamics of aircraft has been demonstrated.

Carden, H. D.↗
NASA NTRS1975

FCAP - A new tool for the evaluation of active control technology

A computer program has been developed for the evaluation of flight control systems designed for flexible aircraft. This Flight Control Analysis Program (FCAP) is designed in a modular fashion to incorporate sensor, actuator, and control logic element dynamics as well as aircraft dynamics and aerodynamics for complex configurations. Formulation of the total aircraft dynamic system is accomplished in matrix form by casting the equations in state vector format. The system stability and performance are determined in either the frequency or time domain using classical analysis techniques. The aerodynamic method used also permits evaluation of the flutter characteristics of the aircraft.

Noll, R. B.↗
NASA NTRS1986

Updated Thermal-Radiation Program

Thermal Radiation Analyzer System, TRASYS II, is computer-software system with generalized capability to solve radiation-related aspects of thermal-analysis problems. Used in conjunction with generalized thermal-analysis program, any thermal problem expressed in terms of lumped-parameter R-C thermal network solved.

Vogt, R. A.↗
NASA NTRS2005

Theoretical Investigations of Clouds and Aerosols in the Stratosphere and Upper Troposphere

support of the Atmospheric Chemistry Modeling and Data Analysis Program. We investigated a wide variety of issues involving ambient stratospheric aerosols, polar stratospheric clouds or heterogeneous chemistry, analysis of laboratory data, and particles in the upper troposphere. The papers resulting from these studies are listed below. In addition, I participated in the 1999-2000 SOLVE mission as one of the project scientists and in the 2002 CRYSTAL field mission as one of the project scientists. Several CU graduate students and research associates also participated in these mission, under support from the ACMAP program, and worked to interpret data. During the past few years my group has completed a number of projects under the

Toon, Owen B.↗
NASA NTRS1983

Structural Optimization

Programming Structural Synthesis System (PROSSS) provides structural synthesis capability by combining SPAR and CONMIN computer programs with set of interface procedures. SPAR is large general-purpose finite-element structural-analysis program, and CONMIN is large general-purpose optimization program. User supplies two small problem-dependent programs to define design variables, constraints, and objective function.

Rogers, J. L., Jr↗
NASA NTRS1983

Flight test derived heating math models for critical locations on the orbiter during reentry

An analysis technique was developed for expanding the aerothermodynamic envelope of the Space Shuttle without subjecting the vehicle to sustained flight at more stressing heating conditions. A transient analysis program was developed to take advantage of the transient maneuvers that were flown as part of this analysis technique. Heat rates were derived from flight test data for various locations on the orbiter. The flight derived heat rates were used to update heating models based on predicted data. Future missions were then analyzed based on these flight adjusted models. A technique for comparing flight and predicted heating rate data and the extrapolation of the data to predict the aerothermodynamic environment of future missions is presented.

Hertzler, E. K.↗
NASA NTRS1990

Modeling of internal contaminant deposition on a cold instrument sensor

A model is developed to predict the deposition of contaminants on the CCD sensors of the Wide Field Planetary Camera to determine expected performance parameters. Contaminant deposition due to internal instrument sources is considered as is the mechanism of transport to the CCDs themselves. The Contamination Analysis Program (CAP) model considers deposition and reemission kinetics, nodal containment sources, and internodal shape factors related to line-of-sight transport. Indirect transport is also accounted for in the CAP model by considering the effect of diffuse reflection at internodal exchanges. The effective total transport factors for each node-to-node exchange is precalculated to reduce the effective number of nodes and reducing run time of the CAP program. The method is applied to four distinct conditions and is found to be suitable for the analysis of internal self-contamination. Cold traps, venting, and vacuumlike design are factors which are found to be important for cold-sensitive sensors.

Barengoltz, Jack B.↗
NASA NTRS2014

Improving Coverage of Test Cases Generated by Symbolic PathFinder for Programs with Loops

Symbolic execution is a program analysis technique that is used for many purposes, one of which is test-case generation. For loop-free programs, this generates a test-set that achieves path coverage. Program loops, however, imply exponential growth of the number of paths in the best case and non-termination in the worst case. In practice, the number of loop unwindings needs to be bounded for analysis. We consider symbolic execution in the context of the tool Symbolic Pathfinder. This tool extends the model-checker Java Pathfinder and relies on its bounded state-space exploration for termination. We present an implementation of k-bounded loop unwinding, which increases the amount of user-control over the symbolic execution of loops. Bounded unwinding can be viewed as a naive way to prune paths through loops. When using symbolic execution for test-case generation, naively pruning paths is likely at the cost of coverage. In order to improve coverage of branches within a loop body, we present a technique that semi-automatically concretizes variables used in a loop. The basic technique is limited and we therefore present annotations to manually steer symbolic execution towards certain branches, as well as ideas on how the technique can be extended to be more widely applicable.

Programs With Loops↗