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NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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NASA's Jet Propulsion Laboratory has developed a computer model for planning future health care needs in the Los Angeles area. The model integrates demographic health and other data to provide rational projections of hospital bed and physician specialty requirements.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, HEALTH, HOSPITALS, PHYSICIANS
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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Topics on the slide include:quality, test coverage, functional criticality, exposure, criticality, and risk index.
Topics: NASA Technical Reports Server (NTRS), MODELS, RISK, COMPUTER PROGRAMS, COMPUTERIZED SIMULATION,...
A self-consistent computer code for particle simulations which could treat both Landau and cyclotron interactions is discussed.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, ELECTRIC FIELDS, PARTICLE...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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The Coastal Center and the NASA Biomedical Team are working together to adapt a suspension device that simulates weightlessness. Attempts to approximate weightlessness have led astronauts underwater and into harnesses that suspend all or part of their weight. One such device, built at Langley Research Center, is being transferred to rehabilitation work. It can help a person walk and re-learn muscular coordination following a stroke. Hospitals could use it to lift handicapped persons.
Topics: NASA Technical Reports Server (NTRS), GRAVITATION, COMPUTERIZED SIMULATION, MECHANICAL DEVICES,...
A catalog is presented of subsystem and environment math models used or planned for space shuttle simulations. The purpose is to facilitate sharing of similar math models between shuttle simulations. It provides information on mach model requirements, formulations, schedules, and contact persons for further information.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, MATHEMATICAL MODELS, SPACE SHUTTLES,...
The computerized design, methods for generation, simulation of meshing, and enhanced stress analysis of modified involute helical gears is presented. The approaches proposed for modification of conventional involute helical gears are based on conjugation of double-crowned pinion with a conventional helical involute gear. Double-crowning of the pinion means deviation of cross-profile from an involute one and deviation in longitudinal direction from a helicoid surface. Using the method developed,...
Topics: NASA Technical Reports Server (NTRS), COMPUTER AIDED DESIGN, GEARS, STRESS ANALYSIS, COMPUTERIZED...
Flight simulators can be designed to train pilots or assess their flight performance. Low-Fidelity simulators maximize the initial learning rate of novice pilots and minimize initial costs; whereas, expensive, high-fidelity simulators predict the realworld in-flight performance of expert pilots (Fink & Shriver, 1978 Hays & Singer 1989; Kinkade & Wheaton. 1972). Although intuitively appealing and intellectually convenient to generalize concepts of learning and assessment, what holds...
Topics: NASA Technical Reports Server (NTRS), FLIGHT SIMULATORS, EDUCATION, AERONAUTICS, COMPUTERIZED...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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In 1984, researchers from Ames Research Center came together to develop advanced human interfaces for NASA s teleoperations that would come to be known as "virtual reality." The basis of the work theorized that if the sensory interfaces met a certain threshold and sufficiently supported each other, then the operator would feel present in the remote/synthetic environment, rather than present in their physical location. Twenty years later, this prolific research continues to pay...
Topics: NASA Technical Reports Server (NTRS), HEARING, TELEOPERATORS, COMPUTERIZED SIMULATION, VIRTUAL...
To determine how dilution of microbial communities affects the diversity of the diluted assemblage a series of numerical simulations were conducted that determined the theoretical change in diversity, richness, and evenness of the community with serial dilution. The results of the simulation suggested that the effects are non linear with a high degree of dependence on the initial evenness of the community being diluted. A series of incubation experiments using a range of dilutions of raw sewage...
Topics: NASA Technical Reports Server (NTRS), DILUTION, MICROORGANISMS, COMPUTERIZED SIMULATION,...
The Kennedy Space Center (KSC) Electrostatics and Surface Physics Laboratory is participating in an Innovative Partnership Program (IPP) project with an industry partner to modify a commercial off-the-shelf simulation software product to treat the electrodynamics of particulate systems. Discrete element modeling (DEM) is a numerical technique that can track the dynamics of particle systems. This technique, which was introduced in 1979 for analysis of rock mechanics, was recently refined to...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, ELECTROSTATICS, CHARGED PARTICLES,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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Previous studies have shown that satellite servicing is cost effective; however, all of these studies were of different formats, dollar year, learning rates, availability, etc. Threfore, it was difficult to correlate any useful trends from these studies. The reviewed study was initiated to correlate the economic data into a common data base, using a common set of assumptions. A selected set of existed funded programs was then analyzed to provide an independent analysis of the servicing options...
Topics: NASA Technical Reports Server (NTRS), DATA BASES, ECONOMICS, SPACECRAFT MAINTENANCE, COMPUTERIZED...
Its time: a) To bring planetary scientists, deflection system investigators and vehicle designers together on the characterization/mitigation problem. b) To develop a comprehensive trade space of options. c) To trade options under a common set of assumptions and see what comparisons on effectiveness can be made. d) To explore the synergy that can be had with proposed scientific and exploration architectures while interest in NEO's are at an all time high.
Topics: NASA Technical Reports Server (NTRS), DESIGN ANALYSIS, COMPUTERIZED SIMULATION, IDENTIFYING,...
This slide presentation reviews the internship assignment of the author and his work on the GFSSP among other assignments.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, FLUID FLOW, COMPUTER PROGRAMS,...
NASA Network Resource and Training Site
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This document summarizes the activities of the Goddard Earth Sciences and Technology Center (GEST), a consortium of scientists and engineers led by the University of Maryland, Baltimore County (UMBC), during the contract reporting period. Topics covered include: new programs, eligibility and selection criteria, Goddard Coastal Research Graduate Fellowship Program and staffing changes.
Topics: NASA Technical Reports Server (NTRS), STUDENTS, EDUCATION, UNIVERSITIES, EARTH SCIENCES,...
Land surface models (LSMs) play a critical role in the simulation of climate, for they determine the character of a large fraction of the atmosphere's lower boundary. The LSM partitions the net radiative energy at the land surface into sensible heat, latent heat, and energy storage, and it partitions incident precipitation water into evaporation, runoff, and water storage. Numerous modeling experiments and the existing (though very scant) observational evidence suggest that variations in these...
Topics: NASA Technical Reports Server (NTRS), PARAMETERIZATION, COMPUTERIZED SIMULATION, DRAINAGE,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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This is a report of my activities as a NASA Fellow during the summer of 2003 at the NASA Kennedy Space Center (KSC). The core of these activities is the assigned project: the Virtual Test Bed (VTB) from the Spaceport Engineering and Technology Directorate. The VTB Project has its foundations in the NASA Ames Research Center (ARC) Intelligent Launch & Range Operations program (ILRO). The objective of the VTB project is to develop a unique collaborative computing environment where simulation...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, SYSTEMS SIMULATION, LAUNCHING BASES,...
During the investigation we have finalized the event studies that are necessary for the development of the magnetopause model and for the calibration of our simulation code.
Topics: NASA Technical Reports Server (NTRS), MAGNETOPAUSE, COMPUTERIZED SIMULATION, MODELS, CALIBRATING,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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An aerodynamic bicycle wheel developed by two DuPont engineers and a California company incorporates research into NASA airfoils. Computer modeling was accomplished with MSC/NASTRAN. Each of the three spokes in the wheel is, in effect, an airfoil, maximizing aerodynamic efficiency for racing.
Topics: NASA Technical Reports Server (NTRS), WHEELS, AERODYNAMIC CHARACTERISTICS, RECREATION, COMPUTER...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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"Elizabeth," a computerized beauty analysis system marketed by Elizabeth Arden, is based upon an ARAC data base search of technologies measuring skin profiles. * "Elizabeth" is no longer commercially available.
Topics: NASA Technical Reports Server (NTRS), COMPUTER TECHNIQUES, DIAGNOSIS, SKIN (ANATOMY), DATA BASES,...
An investigation into the application of an observer based sliding mode controller for robust control of a highly unstable aircraft and methods of compensating for actuator dynamics is performed. After a brief overview of some reconfigurable controllers, sliding mode control (SMC) is selected because of its invariance properties and lack of need for parameter identification. SMC is reviewed and issues with parasitic dynamics, which cause system instability, are addressed. Utilizing sliding...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT CONTROL, AIRCRAFT STABILITY, ACTUATORS, COMPUTERIZED...
The feasibility is evaluated of an evolutionary development for use of a single-axis gimbal star tracker from prior two-axis gimbal star tracker based system applications. Detailed evaluation of the star tracker gimbal encoder is considered. A brief system description is given including the aspects of tracker evolution and encoder evaluation. System analysis includes evaluation of star availability and mounting constraints for the geosynchronous orbit application, and a covariance simulation...
Topics: NASA Technical Reports Server (NTRS), ATTITUDE INDICATORS, GIMBALS, STAR TRACKERS, COMPUTER...
During the final year of this investigation we have finished several event studies that we considered necessary for the development of a tail magnetopause model and for the calibration of our simulation code. We have not reached the ultimate goal of the project, i.e., the development of an analytical tail magnetopause model. In the course of the investigation we have learned that such a model would be much more complex than we had anticipated. However, the investigations that we conducted...
Topics: NASA Technical Reports Server (NTRS), MAGNETOPAUSE, COMPUTERIZED SIMULATION, MODELS, MATHEMATICAL...
Some of the processes involved in the nucleation and growth of thin films were simulated by means of a digital computer. The simulation results were used to study the nucleation and growth kinetics resulting from the various processes. Kinetic results obtained for impingement, surface migration, impingement combined with surface migration, and with reevaporation are presented. A substantial fraction of the clusters may form directly upon impingement. Surface migration results in a decrease in...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, NUCLEATION, THIN FILMS, CRYSTAL...
The logistics of orbital vehicle servicing computer specifications was developed and a number of alternatives to improve utilization of the space shuttle and the tug were investigated. Preliminary results indicate that space servicing offers a potential for reducing future operational and program costs over ground refurbishment of satellites. A computer code which could be developed to simulate space servicing is presented.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, LOGISTICS, SPACE SHUTTLES, SPACE...
Current system simulations are mature, difficult to modify, and poorly documented. Probabilistic life prediction techniques for space applications are in their early application stage. Many parts of the full system, variable fidelity simulation, have been demonstrated individually or technology is available from aeronautical applications. A 20% reduction in time to design with improvements in performance and risk reduction is anticipated. GRC software development will proceed with similar...
Topics: NASA Technical Reports Server (NTRS), PREDICTION ANALYSIS TECHNIQUES, COMPUTERIZED SIMULATION,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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No abstract available
Topics: NASA Technical Reports Server (NTRS), SUPERCOMPUTERS, NASA PROGRAMS, COMPUTERIZED SIMULATION,...
Differential Evolution is a simple, fast, and robust evolutionary algorithm that has proven effective in determining the global optimum for several difficult single-objective optimization problems. In this paper, the Differential Evolution algorithm is extended to multiobjective optimization problems by using a Pareto-based approach. The algorithm performs well when applied to several test optimization problems from the literature.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, OPTIMIZATION, COMPUTERIZED SIMULATION, Madavan,...
NASA engineers use simulation software to detect and prevent interference between different radio frequency (RF) systems on a rocket and satellite before launch. To speed up the process, Kennedy Space Center awarded SBIR funding to Champaign, Illinois-based Delcross Technologies LLC, which added a drag-and-drop feature to its commercial simulation software, resulting in less time spent preparing for the analysis.
Topics: NASA Technical Reports Server (NTRS), ARTIFICIAL SATELLITES, LAUNCHING, RADIO FREQUENCIES,...
The design, fabrication, testing, and evaluation of components for a modularized engineering prototype of a unified system for detection of life on Mars is summarized.
Topics: NASA Technical Reports Server (NTRS), EXTRATERRESTRIAL LIFE, MARS (PLANET), BIOLOGY, COMPUTERIZED...
A frequency sub-band based adaptive spectral subtraction algorithm is developed to remove noise from noise-corrupted speech signals. A single microphone is used to obtain both the noise-corrupted speech and the estimate of the statistics of the noise. The statistics of the noise are estimated during time frames that do not contain speech. These statistics are used to determine if future time frames contain speech. During speech time frames, the algorithm determines which frequency sub-bands...
Topics: NASA Technical Reports Server (NTRS), NOISE REDUCTION, SIGNAL PROCESSING, COMPUTERIZED SIMULATION,...
The Applied Meteorology Unit (AMU) evaluated the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS provides emergency response guidance for Cape Canaveral Air Force Station and Kennedy Space Center operations in the event of an accidental hazardous material release or aborted vehicle launch. The RAMS prognostic data are available to ERDAS for display and are used to initialize the 45th Space Wing/Range Safety dispersion...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC MODELS, WEATHER FORECASTING, COMPUTERIZED...
NASA Network Resource and Training Site
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Being "lost" is an exemplar of imperfect Situation Awareness/Situation Understanding (SA/SU) -- information/knowledge that is uncertain, incomplete, and/or just wrong. Being "lost" may be a geo-spatial condition - not knowing/being wrong about where to go or how to get there. More broadly, being "lost" can serve as a metaphor for uncertainty and/or inaccuracy - not knowing/being wrong about how one fits into a larger world view, what one wants to do, or how to do...
Topics: NASA Technical Reports Server (NTRS), SITUATIONAL AWARENESS, COMPUTERIZED SIMULATION, VIRTUAL...
The radiation models were compared on the basis of the approaches used for the transport calculations and absorption coefficients and of results obtained for the radiation flux profiles and spectral distributions. The calculated results were for shock layer conditions representative of manned earth reentry from an interplanetary mission. The three models are RATRAP, RADICAL, and MDAC. The results show that significant differences exist in the radiation flux computed by the three models. The...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC HEATING, COMPUTERIZED SIMULATION, HYPERSONIC...
NASA Network Resource and Training Site
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Catherine Huybrechts Burton founded San Francisco-based Endpoint Environmental (2E) LLC in 2005 while she was a student intern and project manager at Ames Research Center with NASA's DEVELOP program. The 2E team created the Tire Identification from Reflectance model, which algorithmically processes satellite images using turnkey technology to retain only the darkest parts of an image. This model allows 2E to locate piles of rubber tires, which often are stockpiled illegally and cause hazardous...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, HAZARDS, EARTH ENVIRONMENT,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first...
Topics: NASA Technical Reports Server (NTRS), ACTUATORS, COMPUTERIZED SIMULATION, HYDRAULIC EQUIPMENT,...
An algorithm for computationally lightweight simulation of automated air traffic control (ATC) at a busy airport has been derived. The algorithm is expected to serve as the basis for development of software that would be incorporated into flight-simulator software, the ATC component of which is not yet capable of handling realistic airport loads. Software based on this algorithm could also be incorporated into other computer programs that simulate a variety of scenarios for purposes of training...
Topics: NASA Technical Reports Server (NTRS), AIR TRAFFIC CONTROL, COMPUTER PROGRAMS, FLIGHT PLANS,...
Aerogels have been of interest to the aerospace community primarily for their thermal properties, notably their low thermal conductivities. While such gels are typically fragile, recent advances in the application of conformal polymer layers to these gels has made them potentially useful as lightweight structural materials as well. We have previously performed computer simulations of aerogel thermal conductivity and tensile and compressive failure, with results that are in qualitative, and...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, AEROGELS, FAILURE, THERMAL...
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Prior to the SOLVE deployment, we modified and ran a chemical transport model (CTM) to set up a stratospheric climatology for 1 September 1999. During and immediately following the SOLVE deployments, we ran the model in near-real-time and used these results in conjunction with SOLVE observations to draw conclusions about stratospheric transport.
Topics: NASA Technical Reports Server (NTRS), CLIMATOLOGY, STRATOSPHERE, POLAR REGIONS, COMPUTERIZED...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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North American Marine Jet (NAMJ), Inc. received assistance from Marshall Space Flight Center engineers in the Computational Fluid Dynamics (CFD) branch of the Structure and Dynamics Laboratory in improving the proposed design of a new impeller for their jet-propulsion systems. Marshall used advanced CFD techniques, which included creating a three-dimensional computer model of the impeller for analysis. With Marshall input, the company modified the design, then Marshall used a computer model to...
Topics: NASA Technical Reports Server (NTRS), TECHNOLOGY UTILIZATION, IMPELLERS, COMPUTATIONAL FLUID...
NASA Network Resource and Training Site
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To help reduce the time needed to analyze data from missions like those studying the Sun, Goddard Space Flight Center awarded SBIR funding to Tech-X Corporation of Boulder, Colorado. That work led to commercial technologies that help scientists accelerate their data analysis tasks. Thanks to its NASA work, the company doubled its number of headquarters employees to 70 and generated about $190,000 in revenue from its NASA-derived products.
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, COMPUTER GRAPHICS, DATA PROCESSING,...
In this paper, we analyze the performance of Transmission Control Protocol (TCP) in a network that consists of both satellite and terrestrial components. One method, proposed by outside research, to improve the performance of data transfers over satellites is to use a performance enhancing proxy often dubbed 'spoofing.' Spoofing involves the transparent splitting of a TCP connection between the source and destination by some entity within the network path. In order to analyze the impact of...
Topics: NASA Technical Reports Server (NTRS), PROTOCOL (COMPUTERS), COMPUTERIZED SIMULATION, COMPUTER...
NASA Network Resource and Training Site
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Simulation equations are developed for first and second order digital phase locked loops. Examples of loop simulation are given to determine loop performance with respect to several loop parameters.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DIGITAL SYSTEMS, PHASE LOCKED...
This document is the final report for the project entitled "Upgrades to the Probabilistic NAS Platform Air Traffic Simulation Software." This report consists of 17 sections which document the results of the several subtasks of this effort. The Probabilistic NAS Platform (PNP) is an air operations simulation platform developed and maintained by the Saab Sensis Corporation. The improvements made to the PNP simulation include the following: an airborne distributed separation assurance...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, AIR TRAFFIC, AIR TRAFFIC CONTROL,...
A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard...
Topics: NASA Technical Reports Server (NTRS), MARS ATMOSPHERE, ELECTROSTATICS, STATICS, COMPUTERIZED...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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NASA wanted to know how astronauts' bodies would react under various gravitational pulls and space suit weights. Under contract to NASA, the University of Michigan's Center for Ergonomics developed a model capable of predicting what type of stress and what degree of load a body could stand. The algorithm generated was commercialized with the ISTU (Isometric Strength Testing Unit) Functional Capacity Evaluation System, which simulates tasks such as lifting a heavy box or pushing a cart and...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE MEDICINE, COMPUTERIZED SIMULATION, GRAVITATIONAL...
This booklet and the accompanying diskette contain the materials necessary to collect subjective workload assessments with the NASA Task Load Index on IBM PC compatible microcomputers. This procedure for collecting workload ratings was developed by the Human Performance Group at NASA Ames Research Center during a three year research effort that involved more than 40 laboratory, simulation, and inflight experiments Although the technique is still undergoing evaluation, this package is being...
Topics: NASA Technical Reports Server (NTRS), WORKLOADS (PSYCHOPHYSIOLOGY), HUMAN PERFORMANCE,...
NASA Network Resource and Training Site
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The goal of this project is to develop a magneto-hydrodynamic (MHD) computer code for simulation of the VASIMR engine. This code is designed be easy to modify and use. We achieve this using the Cactus framework, a system originally developed for research in numerical relativity. Since its release, Cactus has become an extremely powerful and flexible open source framework. The development of the code will be done in stages, starting with a basic fluid dynamic simulation and working towards a...
Topics: NASA Technical Reports Server (NTRS), MAGNETOHYDRODYNAMICS, COMPUTER PROGRAMS, COMPUTERIZED...
The validation of the results of physically-based mathematical models against experimental results was discussed. Systematic techniques are used for: (1) isolating subsets of the simulator mathematical model and comparing the response of each subset to its experimental response for the same input conditions; (2) evaluating the response error to determine whether it is the result of incorrect parameter values, incorrect structure of the model subset, or unmodeled external effects of cross...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, FLIGHT SIMULATION, HELICOPTERS,...
The objectives of this project are to: (1) perform a numerical simulation of the jet screech phenomenon; and (2) use the data of the simulations to obtain a better understanding of the physics of jet screech. The original grant period was for three years. This was extended at no cost for an extra year to allow the principal investigator time to publish the results. We would like to report that our research work and results (supported by this grant) have fulfilled both objectives of the grant....
Topics: NASA Technical Reports Server (NTRS), AEROACOUSTICS, COMPUTERIZED SIMULATION, SCREECH TONES, THREE...
NASA Network Resource and Training Site
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No abstract available
Topics: NASA Technical Reports Server (NTRS), ELECTRIC MOTORS, ROTORS, MAGNETIC MATERIALS, ACCESSORIES,...
The goal of this study is to better understand how TCP behaves over noisy, high-latency links such as satellite links and propose improvements to TCP implementations such that TCP might better handle such links. This report is comprised of a series of smaller reports, presentations and recommendations. Included in these documents are a summary of the TCP enhancement techniques for large windows, protect against wrap around (PAWS), use of selective acknowledgements (SACK), increasing TCP's...
Topics: NASA Technical Reports Server (NTRS), RESEARCH, COMPUTERIZED SIMULATION, AUGMENTATION, DATA LINKS,...
A finite-difference computer program (COSIM) has been written which models the one-dimensional, diffusional transport associated with high-temperature oxidation and interdiffusion of overlay-coated substrates. The program predicts concentration profiles for up to three elements in the coating and substrate after various oxidation exposures. Surface recession due to solute loss is also predicted. Ternary cross terms and concentration-dependent diffusion coefficients are taken into account. The...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, OXIDATION, COMPUTERIZED SIMULATION,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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It is shown that a simple two-link planar manipulator exhibits a phenomenon of global instability in a subspace of its configuration space. A numerical example, as well as results of a graphic simulation, is given.
Topics: NASA Technical Reports Server (NTRS), CHAOS, MANIPULATORS, MECHANICAL DEVICES, ROBOTICS, ROBOTS,...
The Transient Cryogen Transfer Computer Program (TCTP) developed and verified for LOX systems by analyses of Skylab S-1B stage loading data from John F. Kennedy Space Center launches was extended to include hydrogen as the working fluid. The feasibility of incorporating TCTP into the space shuttle main engine dynamic model was studied. The program applications are documented.
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, LIQUID HYDROGEN, SPACE SHUTTLES,...
This report documents the first stage of research into Control Law - Control Allocation Interactions. A three-year research effort was originally proposed: 1. Create a desktop flight simulation environment under which experiments related to the open questions may be conducted. 2. Conduct research to determine which aspects of control allocation have impact upon control law design that merits further research. 3. Conduct research into those aspects of control allocation identified above, and...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DYNAMIC CONTROL, FLIGHT SIMULATION,...
NASA Network Resource and Training Site
by NASA Technical Reports Server (NTRS)
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No abstract available
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, AIRFRAMES, ICE FORMATION, SCANNERS,...
This presentation will discuss methods to which ModelCheck can be implemented to not only improve model quality, but also satisfy both employees and management through different sets of quality checks. This approach allows a standard set of modeling practices to be upheld throughout a company, with minimal interaction required by the end user. The presenter will demonstrate how to create multiple ModelCheck standards, preventing users from evading the system, and how it can improve the quality...
Topics: NASA Technical Reports Server (NTRS), MODELS, COMPUTERIZED SIMULATION, PROCEDURES, QUALITY CONTROL,...
Calculating an accurate nutation time constant (NTC), or nutation rate of growth, for a spinning upper stage is important for ensuring mission success. Spacecraft nutation, or wobble, is caused by energy dissipation anywhere in the system. Propellant slosh in the spacecraft fuel tanks is the primary source for this dissipation and, if it is in a state of resonance, the NTC can become short enough to violate mission constraints. The Spinning Slosh Test Rig (SSTR) is a forced-motion spin table...
Topics: NASA Technical Reports Server (NTRS), LIQUID SLOSHING, MATHEMATICAL MODELS, NUTATION, SPACECRAFT...
The longitudinal dynamics of a medium range twin-jet or tri-jet transport aircraft are simulated. For the climbing trajectory, the thrust is constrained to maximum value, and for descent, the thrust is set at idle. For cruise, the aircraft is held in the trim condition. For climb or descent, the aircraft is steered to follow either (a) a fixed profile which is input to the program or (b) a profile computed at the beginning of that segment of the run. For climb, the aircraft is steered to...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT CONTROL, LONGITUDINAL CONTROL, TRANSPORT AIRCRAFT,...
Simulation results obtained by using FUN2D for robust airfoil shape optimization in transonic viscous flow are included to show the potential of the profile optimization method for generating fairly smooth optimal airfoils with no off-design performance degradation.
Topics: NASA Technical Reports Server (NTRS), SHAPE OPTIMIZATION, AIRFOILS, VISCOUS FLOW, COMPUTERIZED...
Computer simulations were conducted to analyze the performance and operating cost of a photovoltaic energy source combined with a diesel generator system and battery storage. The simulations were based on the load demand profiles used for the design of an all photovoltaic energy system installed in the remote Papago Indian Village of Schuchuli, Arizona. Twenty year simulations were run using solar insolation data from Phoenix SOLMET tapes. Total energy produced, energy consumed, operation and...
Topics: NASA Technical Reports Server (NTRS), DIESEL ENGINES, ELECTRIC BATTERIES, PHOTOVOLTAIC CELLS,...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE ENGINEERING, CONTROL, MULTIPROCESSING (COMPUTERS),...
A summary of previously proposed receiver strategies for direct-detection laser ranging receivers is presented. Computer simulations are used to compare performance of candidate implementation strategies in the 1- to 100-photoelectron region. Under the condition of no background radiation, the maximum-likelihood and minimum mean-square error estimators were found to give the same performance for both bell-shaped and rectangular optical-pulse shapes. For signal energies greater than 100...
Topics: NASA Technical Reports Server (NTRS), LASER RANGE FINDERS, OPTICAL RADAR, RECEIVERS, COMPARISON,...
NASA Network Resource and Training Site
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We propose a new approach to performing ultrafast beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The strategy is demonstrated by numerical simulation, showing a beam switching of 10 deg at 42 GHz.
Topics: NASA Technical Reports Server (NTRS), BEAM SWITCHING, COMPUTERIZED SIMULATION, SURFACE EMITTING...
A computer program which simulates the complex processes of photooxidation which take place in a polymer upon prolonged exposure outdoors causing it to fail in photovoltaic and other applications. The method calculates from an input data set of elementary reactions and rates the concentration profiles of all species over time.
Topics: NASA Technical Reports Server (NTRS), PHOTOOXIDATION, POLYMERIZATION, SOLAR CELLS, COMPUTERIZED...
Researchers at the NASA Glenn Research Center acquired a commodity cluster based on Intel Corporation processors to compare its performance with a traditional UNIX cluster in the execution of aeropropulsion applications. Since the cost differential of the clusters was significant, a cost/performance ratio was calculated. After executing a propulsion application on both clusters, the researchers demonstrated a 9.4 cost/performance ratio in favor of the Intel-based cluster. These researchers...
Topics: NASA Technical Reports Server (NTRS), SUPERCOMPUTERS, COMPUTER SYSTEMS PERFORMANCE, CENTRAL...
This study examined different constellation configurations to determine their suitability for the Mars Network. Some variations on the baseline case of four circular orbits were initially studied. Eccentric orbits were then used to determine their effects on several figures of merit that were selected as representative of the design goals. It was eventually found that the use of eccentric orbits in combination with circular orbits can improve aspects of some navigation and communication figures...
Topics: NASA Technical Reports Server (NTRS), CIRCULAR ORBITS, SATELLITE CONSTELLATIONS, ECCENTRIC ORBITS,...
The earliest abort once around (AOA) time for the first orbital flight test (OFT-1) mission is determined. The latest estimates of vehicle weights and propulsion for OFT-1 are used. Trade analyses to indicate variations in AOA time for shuttle subsystem changes (such as orbital maneuvering system (OMS) or reaction control system (RCS) propellant loadings) are included. In addition, the effects of first stage attitude steering as a function of relative velocity for a nominal profile are...
Topics: NASA Technical Reports Server (NTRS), ABORT TRAJECTORIES, FLIGHT TESTS, SPACE SHUTTLES,...
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The robustness of detection filters applied to the detection of actuator failures on a free-free beam is analyzed. This analysis is based on computer simulation tests of the detection filters in the presence of different types of model mismatch, and on frequency response functions of the transfers corresponding to the model mismatch. The robustness of detection filters based on a model of the beam containing a large number of structural modes varied dramatically with the placement of some of...
Topics: NASA Technical Reports Server (NTRS), ACTUATORS, DETECTION, FAILURE ANALYSIS, FILTERS, ROBUSTNESS...
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by NASA Technical Reports Server (NTRS)
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A NASA-developed meter and computer model offers the first verifiable way of measuring ride quality. It transforms individual noise and vibration elements into subjective units, then translates the units into a discomfort index. The meter was designed by Wyle Laboratories under NASA contract. It performs well and has been sold to major manufacturers.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, TECHNOLOGY UTILIZATION, MEASURING...
We developed techniques to predict application execution times for instance-based learning with an average error of 33% of average run time. We developed techniques to predict queue wait times that included a simulation of scheduling algorithms and execution time predictions. We implemented these techniques for the NAS Origin cluster.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, QUEUEING THEORY, MATHEMATICAL MODELS, SCHEDULING,...
The research supported under this award focuses on heterogeneous distributed computing for high-performance applications, with particular emphasis on computational aerosciences. The overall goal of this project was to and investigate issues in, and develop solutions to, efficient execution of computational aeroscience codes in heterogeneous concurrent computing environments. In particular, we worked in the context of the PVM[1] system and, subsequent to detailed conversion efforts and...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE SCIENCES, COMPUTER PROGRAMS, HETEROGENEITY,...
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The objective of this study was to perform theoretical modeling of mechanical deformation of the Earth's lithosphere making use of analytical solutions as well as numerical computer simulations.
Topics: NASA Technical Reports Server (NTRS), LITHOSPHERE, DEFORMATION, MATHEMATICAL MODELS, COMPUTERIZED...
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Marshall Space Flight Center teamed with the University of Alabama in Huntsville (UAH) in 1989 on a program involving development of advanced simulation software. Concurrently, the State of Alabama chartered UAH to conduct a technology advancement program in support of the state's apparel manufacturers. In 1992, under contract to Marshall, UAH developed an apparel-specific software package that allows manufacturers to design and analyze modules without making an actual investment -- it...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, GARMENTS, MANUFACTURING, SOFTWARE...
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Published report describes analytical development and simulation of braking system. System prevents wheels from skidding when brakes are applied, significantly reducing stopping distance. Report also presents computer simulation study on system as applied to aircraft.
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT BRAKES, ANTISKID DEVICES, BRAKES (FOR ARRESTING...
An analytical study was made of the stability of a closed-loop liquid-lithium temperature control of the primary loop of a conceptual nuclear Brayton space powerplant. The operating point was varied from 20 to 120 percent of design. A describing-function technique was used to evaluate the effects of temperature dead band and control coupling backlash. From the system investigation, it was predicted that a limit cycle will not exist with a temperature dead band, but a limit cycle will not exist...
Topics: NASA Technical Reports Server (NTRS), BRAYTON CYCLE, SPACE POWER UNIT REACTORS, TEMPERATURE...
The performance of personnel in the augmentation and improvement of the interactive IMSIM information management simulation model is summarized. With this augmented model, NASA now has even greater capabilities for the simulation of computer system configurations, data processing loads imposed on these configurations, and executive software to control system operations. Through these simulations, NASA has an extremely cost effective capability for the design and analysis of computer-based data...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, INFORMATION MANAGEMENT, MATHEMATICAL...
The evolution of domain walls in the early universe is studied via 2-D computer simulation. The walls are initially configured on a triangular lattice and then released from the lattice, their evolution driven by wall curvature and by the universal expansion. The walls attain an average velocity of about 0.3c and their surface area per volume (as measured in comoving coordinates) goes down with a slope of -1 with respect to conformal time, regardless of whether the universe is matter or...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, COSMOLOGY, DOMAIN WALL, STRING...
The mathematical modeling and programming of a complete simulation program for a space station computer-steered high gain antenna are described. The program provides for reading input data cards, numerically integrating up to 50 first order differential equations, and monitoring up to 48 variables on printed output and on plots. The program system consists of a high gain antenna, an antenna gimbal control system, an on board computer, and the environment in which all are to operate.
Topics: NASA Technical Reports Server (NTRS), ANTENNA DESIGN, COMPUTERIZED SIMULATION, MATHEMATICAL MODELS,...
The equations of motion are developed which describe the dynamic interaction between the spacecraft bus and the movable appendages about a single axis. The effect is evaluated of the dynamic interaction on the attitude control subsystem with computer simulations, and design recommendations to reduce the impact of this interaction on future attitude control subsystems are presented.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, MARINER SPACECRAFT, SPACECRAFT...
A study was conducted to determine the effects of degrading a rotating blade element rotor mathematical model suitable for real-time simulation of rotorcraft. Three methods of degradation were studied, reduction of number of blades, reduction of number of blade segments, and increasing the integration interval, which has the corresponding effect of increasing blade azimuthal advance angle. The three degradation methods were studied through static trim comparisons, total rotor force and moment...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, MATHEMATICAL MODELS, REAL TIME...
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by NASA Technical Reports Server (NTRS)
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The next generation of rocket engine turbopumps is being developed by industry through Government-directed contracts. These turbopumps will use fluid film bearings because they eliminate the life and shaft-speed limitations of rolling-element bearings, increase turbopump design flexibility, and reduce the need for turbopump overhauls and maintenance. The design of the fluid film bearings for these turbopumps, however, requires sophisticated analysis tools to model the complex physical behavior...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, COMPUTERIZED SIMULATION, FLUID FILMS,...
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A series of impact experiments on anhydrite CaSO4, in which vaporized sample accelerates an element in a velocity interferometer, generate velocity data that we have recently reanalyzed using an explicit entropy generating finite difference code. The shock pressure required from the onset, and complete vaporization of 30% porous and 70% crystal density anhydrite is 52 +/- 3 and 122 +/- 13 GPa. Using observed acid leaching in non-marine K/T ejecta in North America, and the sharp global increase...
Topics: NASA Technical Reports Server (NTRS), IMPACT TESTS, CALCIUM SILICATES, VAPORIZING, INTERFEROMETERS,...
The general problem of gyro calibration can be stated as the estimation of the scale factors, misalignments, and drift-rate biases of the gyro using the on-orbit sensor measurements. These gyro parameters have been traditionally treated as temperature-independent in the operational flight dynamics ground systems at NASA Goddard Space Flight Center (GSFC), a scenario which has been successfully applied in the gyro calibration of a large number of missions. A significant departure from this is...
Topics: NASA Technical Reports Server (NTRS), CALIBRATING, GYROSCOPES, TEMPERATURE DEPENDENCE, COMPUTERIZED...
A control model describing a network flow hindered by multiple pure time (or transport) delays is formulated. Feedbacks connect each desired output with a single control sector situated at the origin. The dynamic formulation invokes the use of differential difference equations. This causes the characteristic equation of the model to consist of transcendental functions instead of a common algebraic polynomial. A general graphical criterion is developed to evaluate the stability of such a...
Topics: NASA Technical Reports Server (NTRS), FEEDBACK CONTROL, NETWORK ANALYSIS, COMPUTERIZED SIMULATION,...
During this reporting period, all technical responsibilities were accomplished as planned. A close working relationship was maintained with personnel of the MSFC Avionics Department Software Group (ED14), the MSFC EXPRESS Project Office (FD31), and the Huntsville Boeing Company. Accomplishments included: performing special tasks; supporting Software Review Board (SRB), Avionics Test Bed (ATB), and EXPRESS Software Control Panel (ESCP) activities; participating in technical meetings; and...
Topics: NASA Technical Reports Server (NTRS), AVIONICS, COMPUTERIZED SIMULATION, SOFTWARE ENGINEERING,...
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by NASA Technical Reports Server (NTRS)
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As a Jet Propulsion Laboratory astronomer, John D. Callahan developed a computer program called Multimission Interactive Planner (MIP) to help astronomers analyze scientific and optical data collected on the Voyager's Grand Tour. The commercial version of the program called XonVu is published by XonTech, Inc. Callahan has since developed two more advanced programs based on MIP technology, Grand Tour and Jovian Traveler, which simulate Voyager and Giotto missions. The software allows astronomers...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ASTRONOMY, EDUCATION, NASA SPACE PROGRAMS,...
The Simulation Computer System (SCS) is the computer hardware, software, and workstations that will support the Payload Training Complex (PTC) at the Marshall Space Flight Center (MSFC). The PTC will train the space station payload scientists, station scientists, and ground controllers to operate the wide variety of experiments that will be on-board the Freedom Space Station. The further analysis performed on the SCS study as part of task 2-Perform Studies and Parametric Analysis-of the SCS...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, PAYLOAD STATIONS, PAYLOADS, SPACE...
We explore the utility of various sensors by recovering parachute-probe dynamics information from a package released from a small-scale, remote-controlled airplane. The airdrops aid in the development of datasets for the exploration of planetary probe trajectory recovery algorithms, supplementing data collected from instrumented, full-scale tests and computer models.
Topics: NASA Technical Reports Server (NTRS), AIRDROPS, PARACHUTES, REMOTE CONTROL, TRAJECTORIES, FULL...
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In the past year, we have successfully developed the techniques necessary to conduct impact experiments on ice at very low temperatures. We employ the method of embedding gauges within a target to measure the shock wave and material properties. This means that our data are not model dependent; we directly measure the essential parameters needed for numerical simulations of impact cratering. Since then we have developed a new method for temperature control of icy targets that ensures temperature...
Topics: NASA Technical Reports Server (NTRS), ICE, COMPUTERIZED SIMULATION, IMPACT TESTS, SHOCK WAVES,...
Simple linear rheologies were used with elastic forces driving the main events and viscoelastic forces being important for aftershock and creep occurrence. Friction and its dependence on velocity, stress, and displacement also plays a key role in determining how, when, and where fault motion occurs. The discussion of the qualitative behavior of the simulators focuses on the manner in which energy was stored in the system and released by the unstable and stable sliding processes. The numerical...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, EARTHQUAKES, GEOLOGICAL FAULTS,...
Because of the extreme expense involved in developing and flight testing meteorological instruments, an extensive series of numerical modeling experiments to simulate the performance of meteorological observing systems were performed on CYBER 205. The studies compare the relative importance of different global measurements of individual and composite systems of the meteorological variables needed to determine the state of the atmosphere. The assessments are made in terms of the systems ability...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, METEOROLOGICAL INSTRUMENTS,...
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With the interest in jet propulsion at the end of World War II, aerodynamicists were challenged to develop mathematical models which could be used to design turbomachinery components for jets. NASA Lewis engineers and scientists played a major role in meeting this challenge. Some of their accomplishments are highlighted as well as those of others. Several problems are addressed which must be solved if jet propulsion technology is to advance.
Topics: NASA Technical Reports Server (NTRS), FLOW DISTRIBUTION, JET PROPULSION, MATHEMATICAL MODELS,...
A computerized simulation of a planar phased array of circular waveguide elements is reported using mutual coupling and wide angle impedance matching in phased arrays. Special emphasis is given to circular polarization. The aforementioned computer program has as variable inputs: frequency, polarization, grid geometry, element size, dielectric waveguide fill, dielectric plugs in the waveguide for impedance matching, and dielectric sheets covering the array surface for the purpose of wide angle...
Topics: NASA Technical Reports Server (NTRS), ANTENNA ARRAYS, COMPUTERIZED SIMULATION, PHASED ARRAYS,...
A new approach for determination of machine-tool settings for spiral bevel gears is proposed. The proposed settings provide a predesigned parabolic function of transmission errors and the desired location and orientation of the bearing contact. The predesigned parabolic function of transmission errors is able to absorb piece-wise linear functions of transmission errors that are caused by the gear misalignment and reduce gear noise. The gears are face-milled by head cutters with conical surfaces...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, COMPUTERIZED SIMULATION, GEAR TEETH,...
Computer simulations of the one-on-one aerial combat encounter are generated under the control of specified guidance laws. Given an initial state, the vehicle and atmospheric characteristics, and the guidance laws, the aerial combat encounter is simulated by forward integration of the two vehicles' motions. The development of a combat guidance law which converts positional advantage into an improved firing opportunity is reported. A combination of lag, line of sight, and lead pursuit steering...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT GUIDANCE, COMBAT, FIGHTER AIRCRAFT, HEURISTIC...
The flow of weakly ionized plasmas that is similar to the flow that occurs over rocket-borne blunt probes as they pass through the lower ionosphere has been simulated in a scaled laboratory environment, and electron collection D region blunt probe theories have been evaluated.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, EARTH IONOSPHERE, PLASMAS (PHYSICS),...
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Digital Imaging is the computer processed numerical representation of physical images. Enhancement of images results in easier interpretation. Quantitative digital image analysis by Perceptive Scientific Instruments, locates objects within an image and measures them to extract quantitative information. Applications are CAT scanners, radiography, microscopy in medicine as well as various industrial and manufacturing uses. The PSICOM 327 performs all digital image analysis functions. It is based...
Topics: NASA Technical Reports Server (NTRS), DIGITAL TECHNIQUES, RADIOGRAPHY, IMAGE PROCESSING, COMPUTER...
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This viewgraph presentation gives an overview of the CORSAIR turbomachinery code's status and plans. Details are provided on the CORSAIR algorithms, full- and partial-admission turbine simulations, the Simplex turbine, instantaneous Mach number, unsteady pressure admission graphs, variable fluid property RLV-133 simulations, instantaneous entropy function, pumps and inducers, and future plans.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, PUMPS, COMPUTERIZED SIMULATION, TURBINES,...
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A computer simulation was developed to assess passenger survival during the post-crash evacuation of a transport category aircraft when fire is a major threat. The computer code, FIREVAC, computes individual passenger exit paths and times to exit, taking into account delays and congestion caused by the interaction among the passengers and changing cabin conditions. Simple models for the physiological effects of the toxic cabin atmosphere are included with provision for including more...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT ACCIDENTS, PASSENGERS, SURVIVAL, COMPUTER PROGRAMS,...