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The direct arithmetic processing of adaptive delta modulation (ADM) encoded signals, conversion from ADM encoded signals to pulse code modulation (PCM) encoded signals, and conversion from PCM to ADM encoded signals are discussed. It is shown that signals which are ADM encoded can be arithmetically processed directly, without first decoding. Operating on the DM bit stream, and employing only standard digital hardware, the sum, difference and product can be obtained in PCM and ADM format.
Topics: NASA Technical Reports Server (NTRS), DELTA MODULATION, SIGNAL PROCESSING, TECHNOLOGY UTILIZATION,...
The fabrication and performance of a real time jet engine simulator using a digital computer are discussed. The use of the simulator in developing the components and control system of a jet engine is described. Comparison of data from jet engine simulation tests with actual engine tests was conducted with good agreement.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DYNAMIC CHARACTERISTICS, ENGINE...
A fixed-base, piloted simulation study was conducted to determine the operational benefits that result when air traffic control (ATC) instructions are transmitted to the deck of a transport aircraft over a digital data link. The ATC instructions include altitude, airspeed, heading, radio frequency, and route assignment data. The interface between the flight deck and the data link was integrated with other subsystems of the airplane to facilitate data management. Data from the ATC instructions...
Topics: NASA Technical Reports Server (NTRS), AIR TRAFFIC CONTROL, AIRCRAFT COMMUNICATION, COMPUTERIZED...
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A method of the approximated solution of the problem of accretion on a rapidly moving gravitational center is developed. This solution is obtained in the vicinity of the axis of symmetry in the region of the potential flow. The solution of the problem of stationary gas accretion on a moving gravitational center simulates the movement of a substance in interstellar space in the vicinity of a black hole. A detailed picture of gas accretion on a black hole is of interest in connection with the...
Topics: NASA Technical Reports Server (NTRS), APPROXIMATION, BLACK HOLES (ASTRONOMY), CENTER OF GRAVITY,...
Program documentation concerning the design, implementation, and verification of a computerized model for predicting the steady-state sinusoidal response of radial configured distribution feeders is presented in these appendices.
Topics: NASA Technical Reports Server (NTRS), COMMUNICATION CABLES, COMPUTERIZED SIMULATION, DISTRIBUTED...
The Windshear Training Aid promulgated by the Federal Aviation Administration (FAA) defines the practical recovery maneuver following a microburst encounter as application of maximum thrust accompanied by rotation to an aircraft-specific target pitch attitude. In search of a simple method of determining this target, appropriate to a variety of aircraft types, a computer simulation was used to explore the suitability of a pitch target equal in numerical value to that of the angle of attack...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT MANEUVERS, ATTITUDE (INCLINATION), COMPUTERIZED...
In this work an electromagnetic model and subsequent design is presented for a traveling-wave, coplanar waveguide (CPW) based source that will operate in the THz frequency regime. The radio frequency (RF) driving current is a result of photoexcitation of a thin GaAs membrane using two frequency-offset lasers. The GaAs film is grown by molecular-beam-epitaxy (MBE) and displays sub-ps carrier lifetimes which enable the material conductivity to be modulated at a very high rate. The RF current...
Topics: NASA Technical Reports Server (NTRS), RADIO FREQUENCIES, WAVEGUIDES, CURRENT DISTRIBUTION,...
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by NASA Technical Reports Server (NTRS)
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A computer model was developed in order to examine the effects of the wind field and surface collisions on the Martian saltation cloud. The distribution of incidence speeds and angles assumed by one grain in this model characterizes reasonably well the quantitative physical processes in the saltation cloud. Saltating grains that transfer small fractions of their horizontal momentum to the surface attain higher speeds, rise higher above the surface, and achieve longer trajectories than do...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DUST, MARS SURFACE, SANDS, SEDIMENT...
NASA s ARES I-X vehicle launched on a suborbital test flight from the Eastern Range in Florida on October 28, 2009. NASA generated a Range Safety (RS) flight data package to meet the RS trajectory data requirements defined in the Air Force Space Command Manual 91-710. Some products included in the flight data package were a nominal ascent trajectory, ascent flight envelope trajectories, and malfunction turn trajectories. These data are used by the Air Force s 45th Space Wing (45SW) to ensure...
Topics: NASA Technical Reports Server (NTRS), ARES 1 LAUNCH VEHICLE, COMPUTERIZED SIMULATION, DATA...
The Space shuttle orbiter Reaction Control System's (RCS) plume impingement during proximity operations with Space Station Freedom (SSF) is a structural design driver for the SSF solar panels and radiators. A study underway at JSC is investigating whether the use of an automated approach controller could result in the reduction of plume impingement induced loads during orbiter approach to SSF. Ongoing real time person-in-the-loop (PIL) simulations of an orbiter approaching the SSF show that...
Topics: NASA Technical Reports Server (NTRS), HEAT RADIATORS, IMPINGEMENT, PANELS, PLUMES, SOLAR ARRAYS,...
The primary objective of this work was to demonstrate the feasibility of a new potential/viscous flow coupling procedure for reducing computational effort while maintaining solution accuracy. This closed-loop, overlapped velocity-coupling concept has been developed in a new two-dimensional code, ZAP2D (Zonal Aerodynamics Program - 2D), a three-dimensional code for wing analysis, ZAP3D (Zonal Aerodynamics Program - 3D), and a three-dimensional code for isolated helicopter rotors in hover, ZAPR3D...
Topics: NASA Technical Reports Server (NTRS), COMPUTATIONAL FLUID DYNAMICS, FEEDBACK CONTROL, FLOW...
A high fidelity simulation using a PC based Trick framework has been developed for Johnson Space Center's Morpheus test bed flight vehicle. There is an iterative development loop of refining and testing the hardware, refining the software, comparing the software simulation to hardware performance and adjusting either or both the hardware and the simulation to extract the best performance from the hardware as well as the most realistic representation of the hardware from the software. A Particle...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, OPTIMIZATION, TEST STANDS, AUTOMATIC...
The user's manual for the LOGSIM Program is presented. All program options are explained and a detailed definition of the format of each input card is given. LOGSIM Program operations, and the preparation of LOGSIM input data are discused along with data card formats, postprocessor data cards, and output interpretation.
Topics: NASA Technical Reports Server (NTRS), COMPUTER AIDED DESIGN, COMPUTER PROGRAMS, USER MANUALS...
A landing scheme for landing V/STOL aircraft on rolling ships was sought using computerized simulations. The equations of motion as derived from hydrodynamics, their form and the physical mechanisms involved and the general form of the approximation are discussed. The modeling of the sea is discussed. The derivation of the state-space equations for the DD-963 destroyer is described. Kalman filter studies are presented and the influence of the various parameters is assessed. The effect of...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, ESTIMATES, KALMAN FILTERS, LANDING...
The physical bases of large eddy simulation and subgrid modeling are studied. A subgrid scale similarity model is developed that can account for system rotation. Large eddy simulations of homogeneous shear flows with system rotation were carried out. Apparently contradictory experimental results were explained. The main effect of rotation is to increase the transverse length scales in the rotation direction, and thereby decrease the rates of dissipation. Experimental results are shown to be...
Topics: NASA Technical Reports Server (NTRS), EDDY VISCOSITY, ISOTROPIC TURBULENCE, ROTATION, TURBULENCE...
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by NASA Technical Reports Server (NTRS)
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Many Martian craters are surrounded by ejecta blankets which appear to have been fluidized forming lobate and layered deposits terminated by one or more continuous distal scarps, or ramparts. One of the first hypotheses for the formation of so-called rampart ejecta features was shock-melting of subsurface ice, entrainment of liquid water into the ejecta blanket, and subsequent fluidized flow. Our work quantifies this concept. Rampart ejecta found on all but the youngest volcanic and polar...
Topics: NASA Technical Reports Server (NTRS), PROJECTILE CRATERING, EJECTA, MARS CRATERS, MARS SURFACE,...
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The goal of this project was to characterize the molecular mechanism by which cells recognize and respond to physical forces in their local environment. The project was based on the working hypothesis that cells sense mechanical stresses, such as those due to gravity, through their cell surface adhesion receptors (e.g., integrins) and that they respond as a result of structural arrangements with their internal cytoskeleton (CSK) which are orchestrated through use of tensegrity architecture. In...
Topics: NASA Technical Reports Server (NTRS), CELLS (BIOLOGY), GRAVITATION, MOLECULAR BIOLOGY, STRESS...
NASA is currently working on developing the X-38 Crew Return Vehicle for the Internati6nal Space Station (ISS). The aerodynamics of the X-38 and its enormous 7500 square ft parafoil are extremeJy complicated and must be understood and modeled accurately before the vehicle is actually used for human space flight. A large amount of analysis has been performed on the steady state regions of the flight profile when the parafoil is already open. However, the deployment region of the flight profile...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMICS, DEPLOYMENT, FLIGHT PATHS, PARAFOILS, X-38 CREW...
The technology of advanced composites has matured to the point where these composites are prime contenders for various structural applications. One of the major design considerations for prolonged service of these composites is fatigue due to cyclical hygral (moisture), thermal, and mechanical (hygrothermomechanical) loading conditions. Recent research activities at the NASA Lewis Research Center have led to the development of formal procedures for predicting, using computational simulation,...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE STRUCTURES, COMPUTERIZED SIMULATION, FATIGUE LIFE,...
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This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, SPACECRAFT LAUNCHING, MATHEMATICAL...
Spatial disorientation (SD) is a constant contributing factor to the rate of fatal aviation accidents. SD occurs as a result of perceptual errors that can be attributed in part to the inefficient presentation of synthetic orientation cues via the attitude indicator when external visual conditions are poor. Improvements in the design of the attitude indicator may help to eliminate instrumentation as a factor in the onset of SD. The goal of the present study was to explore several display...
Topics: NASA Technical Reports Server (NTRS), ATTITUDE CONTROL, PERIPHERAL VISION, LIGHT (VISIBLE...
High-resolution multispectral data are becoming widely available for commercial and scientific use. For specific applications, such as agriculture studies, there is a need to quantify the performance of such systems. In many cases, parameters such as GSD and SNR can be optimized. Data sets with varying GSD's for the Landsat ETM+ bands were produced to evaluate the effects of GSD on various algorithms and transformations, such as NDVI, principal component analysis, unsupervised classification,...
Topics: NASA Technical Reports Server (NTRS), SENSORS, EARTH SCIENCES, MULTISPECTRAL RADAR, AIRBORNE...
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A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE STRUCTURES, SHELLS (STRUCTURAL FORMS), SMART...
This paper discusses the source term treatment in the numerical solution of elliptic partial differential equations for an interior grid generation problem in generalized curvilinear coordinates. The geometry considered is that of a planar cross-section of a generic spiral-bevel gear tooth typical of a pinion in the OH-58 helicopter transmission. The source terms used are appropriate for an interior grid domain where all the boundaries are prescribed via a combination of Dirichlet and Neumann...
Topics: NASA Technical Reports Server (NTRS), ELLIPTIC DIFFERENTIAL EQUATIONS, GEAR TEETH, GRID GENERATION...
The analysis of data from the MODIS instrument on the Terra platform to derive global distribution of aerosols assumes a set of relationships between the blue, rho (sub blue), the red, rho (sub red), and 2.1 micrometers, rho (sub 2.1), spectral channels. These relations have been established from a series of measurements indicating that rho (sub blue) approximately 0.5 rho (sub red) approximately 0.25 rho (sub 2.1). Here we use a model to describe the transfer of radiation through a vegetation...
Topics: NASA Technical Reports Server (NTRS), AEROSOLS, ALGORITHMS, IMAGING SPECTROMETERS, SPECTRAL...
This paper reports the progress made towards developing complete blood flow simulation capability in humans, especially in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed to quantify the flow in these devices such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological...
Topics: NASA Technical Reports Server (NTRS), BLOOD FLOW, COMPUTERIZED SIMULATION, THREE DIMENSIONAL FLOW,...
Performance of the two commonly used numerical procedures, one based on artificial compressibility method and the other pressure projection method, are compared. These formulations are selected primarily because they are designed for three-dimensional applications. The computational procedures are compared by obtaining steady state solutions of a wake vortex and unsteady solutions of a curved duct flow. For steady computations, artificial compressibility was very efficient in terms of computing...
Topics: NASA Technical Reports Server (NTRS), INCOMPRESSIBLE FLOW, COMPUTERIZED SIMULATION, PRESSURE...
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This report summarizes research on the effects of target porosity on the mechanics of impact cratering. Impact experiments conducted on a centrifuge provide direct simulations of large-scale cratering on porous asteroids. The experiments show that large craters in porous materials form mostly by compaction, with essentially no deposition of material into the ejecta blanket that is a signature of cratering in less-porous materials. The ratio of ejecta mass to crater mass is shown to decrease...
Topics: NASA Technical Reports Server (NTRS), ASTEROIDS, ASTEROID COLLISIONS, PROJECTILE CRATERING,...
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by NASA Technical Reports Server (NTRS)
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MIDAS, Man-machine Integration Design and Analysis System, is a unique combination of software tools aimed at reducing design cycle time, supporting quantitative predictions of human-system effectiveness and improving the design of crew stations and their associated operating procedures. This project is supported jointly by the US Army and NASA.
Topics: NASA Technical Reports Server (NTRS), CREW WORKSTATIONS, MAN MACHINE SYSTEMS, WEBSITES,...
The orbiting space station being developed by NASA will have many thermal sources and sinks as well as requirements for the transport of thermal energy through large distances. The station is also expected to evolve over twenty or more years from an initial design. As the station evolves, thermal management will become more difficult. Thus, analysis techniques to evaluate the effects of changing various thermal loads and the methods utilized to control temperature distributions in the station...
Topics: NASA Technical Reports Server (NTRS), APPLICATIONS PROGRAMS (COMPUTERS), COMPUTERIZED SIMULATION,...
Object-oriented design of simulation programs appears to be very attractive because of the natural association of components in the simulated system with objects. There is great potential in distributing the simulation across several computers for the purpose of parallel computation and its consequent handling of larger problems in less elapsed time. One approach to such a design is to use "actors", that is, active objects with their own thread of control. Because these objects...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, OBJECT-ORIENTED PROGRAMMING,...
As a number of diverse satellite systems (both Low Earth Orbit and Geostationary systems) are being designed and deployed, it becomes increasingly important to be able to test these systems under realistic traffic loads. While software simulations can provide valuable input into the system design process, it is crucial that the physical system be tested so that actual network devices can be employed and tuned. These tests need to utilize traffic patterns that closely mirror the expected user...
Topics: NASA Technical Reports Server (NTRS), INTERNETS, SATELLITE NETWORKS, COMMUNICATION SATELLITES,...
The stochastic adaptive control of the NASA F-8C digital-fly-by-wire aircraft using the multiple model adaptive control (MMAC) method is presented. The selection of the performance criteria for the lateral and the longitudinal dynamics, the design of the Kalman filters for different operating conditions, the identification algorithm associated with the MMAC method, the control system design, and simulation results obtained using the real time simulator of the F-8 aircraft at the NASA Langley...
Topics: NASA Technical Reports Server (NTRS), ADAPTIVE CONTROL, F-8 AIRCRAFT, FLIGHT CONTROL, AIRCRAFT...
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In this paper we consider the robust control of a thermal mixer using multivariable Sliding Mode Control (SMC). The mixer consists of a mixing chamber, hot and cold fluid valves, and an exit valve. The commanded positions of the three valves are the available control inputs, while the controlled variables are total mass flow rate, chamber pressure and the density of the mixture inside the chamber. Unsteady thermodynamics and linear valve models are used in deriving a 5th order nonlinear system...
Topics: NASA Technical Reports Server (NTRS), SLIDING, MATHEMATICAL MODELS, CONTROL SYSTEMS DESIGN, MIXING,...
The following areas related to landing trajectory optimization research were discussed: (1) programming and modifying the steepest descent optimization procedure, (2) successfully iterating toward the optimum for a four-mile trajectory, (3) beginning optimization runs for a twenty-mile trajectory, and (4) adapt wind tunnel data for computer usage. Other related areas were discussed in detail in the two previous annual reports.
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT LANDING, AIRCRAFT NOISE, APPROXIMATION, COMPUTATION,...
Robustness of flexible systems in the presence of model uncertainties at the component level is considered. Specifically, an approach for formulating robustness of flexible systems in the presence of frequency and damping uncertainties at the component level is presented. The synthesis of the components is based on a modifications of a controls-based algorithm for component mode synthesis. The formulation deals first with robustness of synthesized flexible systems. It is then extended to deal...
Topics: NASA Technical Reports Server (NTRS), ROBUSTNESS (MATHEMATICS), ALGORITHMS, TWO DIMENSIONAL MODELS,...
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The conceptual, experimental, and practical aspects of the development of a robot computer problem solving system were investigated. The distinctive characteristics were formulated of the approach taken in relation to various studies of cognition and robotics. Vehicle and eye control systems were structured, and the information to be generated by the visual system is defined.
Topics: NASA Technical Reports Server (NTRS), ARTIFICIAL INTELLIGENCE, COMPUTER TECHNIQUES, PROBLEM...
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Some of the techniques are summarized which are used in constructing C sup 0 and C sup 1 continuous meshes of low degree, implicitly defined, algebraic surface patches in three dimensional space. These meshes of low degree algebraic surface patches are used to construct accurate computer models of physical objects. These meshes are also used in the finite element simulation of physical phenomena (e.g., heat dissipation, stress/strain distributions, fluid flow characteristics) required in the...
Topics: NASA Technical Reports Server (NTRS), ALGEBRA, COMPUTATIONAL GEOMETRY, COMPUTATIONAL GRIDS,...
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A digital computer code and a special purpose hybrid computer, were introduced. The digital computer program, the Root Perturbation Method or RPM, is an implementation of the classic floquet procedure which circumvents numerical problems associated with the extraction of Floquet roots. The hybrid computer, the Wind Energy System Time domain simulator (WEST), yields real time loads and deformation information essential to design and system stability investigations.
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DIGITAL COMPUTERS, ENERGY SOURCES,...
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by NASA Technical Reports Server (NTRS)
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We have used global magnetohydrodynamic, simulations of the interaction between the solar wind and magnetosphere together with single particle trajectory calculations to investigate the sources of plasma entering the magnetosphere. In all of our calculations solar wind plasma primarily enters the magnetosphere when the field line on which it is convecting reconnects. When the interplanetary magnetic field has a northward component the reconnection is in the polar cusp region. In the simulations...
Topics: NASA Technical Reports Server (NTRS), MAGNETOHYDRODYNAMICS, MATHEMATICAL MODELS, COMPUTERIZED...
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by NASA Technical Reports Server (NTRS)
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Most simulation plots are heavily oversampled. Ignoring unnecessary data points dramatically reduces plot time with imperceptible effect on quality. The technique is suited to most plot devices. The departments laser printer's speed was tripled for large simulation plots by data thinning. This reduced printer delays without the expense of a faster laser printer. Surpisingly, it saved computer time as well. All plot data are now thinned, including PostScript and terminal plots. The problem,...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, COMPUTERIZED SIMULATION, LASERS, PRINTERS, RUN...
A generic spinning missile with dithering canards is used to demonstrate the utility of an overset structured grid approach for simulating the aerodynamics of rolling airframe missile systems. The approach is used to generate a modest aerodynamic database for the generic missile. The database is populated with solutions to the Euler and Navier-Stokes equations. It is used to evaluate grid resolution requirements for accurate prediction of instantaneous missile loads and the relative aerodynamic...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC CHARACTERISTICS, DITHERS, MISSILE SYSTEMS,...
Researchers at the NASA Glenn Research Center have enhanced a general-purpose finite element code, NASTRAN, for engine-airframe structural simulations during steady-state and transient operating conditions. For steady-state simulations, the code can predict critical operating speeds, natural modes of vibration, and forced response (e.g., cabin noise and component fatigue). The code can be used to perform static analysis to predict engine-airframe response and component stresses due to maneuver...
Topics: NASA Technical Reports Server (NTRS), AIRFRAMES, STRUCTURAL ANALYSIS, FINITE ELEMENT METHOD,...
Despite the central importance of crew safety in designing and operating a life support system, the metric commonly used to evaluate alternative Advanced Life Support (ALS) technologies does not currently provide explicit techniques for measuring safety. The resilience of a system, or the system s ability to meet performance requirements and recover from component-level faults, is fundamentally a dynamic property. This paper motivates the use of computer models as a tool to understand and...
Topics: NASA Technical Reports Server (NTRS), LIFE SUPPORT SYSTEMS, RESILIENCE, TECHNOLOGY UTILIZATION,...
Magnetic nozzles are used in many laboratory experiments in which plasma flows are to be confined, cooled, accelerated, or directed. At present, however, there is no generally accepted theoretical description that explains the phenomena of plasma expansion in and detachment from an externally-imposed magnetic field. The latter is an especially important problem in the field of plasma propulsion, where the ionized gas must detach from the applied, solenoidal magnetic field to realize thrust...
Topics: NASA Technical Reports Server (NTRS), MAGNETIC FIELD CONFIGURATIONS, MAGNETIC NOZZLES,...
This paper proposes a mean field neural network for the two-dimensional module placement problem. An efficient coding scheme with only O(N log N) neurons is employed where N is the number of modules. The neurons are evolved in groups of N in log N iteration steps such that the circuit is recursively partitioned in alternating vertical and horizontal directions. In our simulations, the network was able to find optimal solutions to all test problems with up to 128 modules.
Topics: NASA Technical Reports Server (NTRS), CODING, COMBINATORIAL ANALYSIS, NEURAL NETS, OPTIMIZATION,...
An approach for solving the compressible Euler and Navier-Stokes equations upon meshes composed of nearly arbitrary polyhedra is described. Each polyhedron is constructed from an arbitrary number of triangular and quadrilateral face elements, allowing the unified treatment of tetrahedral, prismatic, pyramidal, and hexahedral cells, as well the general cut cells produced by Cartesian mesh approaches. The basics behind the numerical approach and the resulting data structures are described. The...
Topics: NASA Technical Reports Server (NTRS), CARTESIAN COORDINATES, COMPRESSIBLE FLOW, COMPUTATIONAL FLUID...
The objective of this paper is to utilize the design methods of modern control theory to realize a dual-adaptive feedback control unit for a highly nonlinear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the nonlinear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator...
Topics: NASA Technical Reports Server (NTRS), ADAPTIVE CONTROL, TURBOJET ENGINES, ALGORITHMS, COMPUTERIZED...
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This viewgraph presentation describes the icing effects, risk mitigation practices, and icing certifications for various Cessna small aircraft models. NASA's role in the development of simulation tools for icing certifications is also discussed.
Topics: NASA Technical Reports Server (NTRS), CESSNA AIRCRAFT, ICE FORMATION, AIRFRAMES, MANUFACTURING,...
In this paper, efficient dynamic simulation algorithms for a system of m manipulators, cooperating to manipulate a large load, are developed; their performance, using two possible forms of parallelism on a general-purpose parallel computer, is investigated. One form, temporal parallelism, is obtained with the use of parallel numerical integration methods. A speedup of 3.78 on four processors of CRAY Y-MP8 was achieved with a parallel four-point block predictor-corrector method for the...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, BODY KINEMATICS, COMPUTERIZED SIMULATION, DYNAMIC...
The Virtual Diagnostics Interface (ViDI) methodology combines two-dimensional image processing and three-dimensional computer modeling to provide comprehensive in-situ visualizations commonly utilized for in-depth planning of wind tunnel and flight testing, real time data visualization of experimental data, and unique merging of experimental and computational data sets in both real-time and post-test analysis. The preparation of such visualizations encompasses the realm of interactive...
Topics: NASA Technical Reports Server (NTRS), DATA BASE MANAGEMENT SYSTEMS, COMPUTERIZED SIMULATION, FLIGHT...
The TERRA spacecraft was launched in December 1999 from Vandenberg Air Force Base, becoming the flagship of NASA's Earth Observing System program to gather data on how the planet's processes create climate. Originally planned as a 5 year mission, it still provides valuable science data after nearly 10 years on orbit. On October 13th, 2009 at 16:23z following a routine inclination maneuver, TERRA experienced a battery cell failure and a simultaneous failure of several battery heater control...
Topics: NASA Technical Reports Server (NTRS), ANOMALIES, CONTROLLERS, TEMPERATURE CONTROL, TERRA...
A C software module has been developed that creates lightweight processes (LWPs) dynamically to achieve parallel computing performance in a variety of engineering simulation and analysis applications to support NASA and DoD project tasks. The required interface between the module and the application it supports is simple, minimal and almost completely transparent to the user applications, and it can achieve nearly ideal computing speed-up on multi-CPU engineering workstations of all operating...
Topics: NASA Technical Reports Server (NTRS), PARALLEL PROCESSING (COMPUTERS), UNIX (OPERATING SYSTEM),...
There are several mechanisms acting at the cold traps that can alter the inventory of volatiles there. Primarily, the lunar surface is bombarded by meteoroids which impact, melt, process, and redistribute the regolith. Further, solar wind and magnetospheric ion fluxes are allowed limited access onto the regions in permanent shadow. Also, although cold traps are in the permanent shadow of the Sun, there is a small flux of radiation incident on the regions from interstellar sources. We...
Topics: NASA Technical Reports Server (NTRS), LUNAR SURFACE, COLD TRAPS, SPACE WEATHERING, COMPUTERIZED...
Computer simulations have been performed for an orbital gradiometer mission to assist in the study of high degree and order gravity field recovery. The simulations were conducted for a satellite in near-circular, frozen orbit at a 160-km altitude using a gravitational field complete to degree and order 360. The mission duration is taken to be 32 days. The simulation provides a set of measurements to assist in the evaluation of techniques developed for the determination of the gravity field....
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, GEOPOTENTIAL, GRAVITATIONAL FIELDS,...
An ongoing project in developing a Task-Level Robot Programming and Simulation System (TARPS) is discussed. The objective of this approach is to design a generic TARPS that can be used in a variety of applications. Many robotic applications require off-line programming, and a TARPS is very useful in such applications. Task level programming is object centered in that the user specifies tasks to be performed instead of robot paths. Graphics simulation provides greater flexibility and also avoids...
Topics: NASA Technical Reports Server (NTRS), ARCHITECTURE (COMPUTERS), COMPUTER GRAPHICS, COMPUTER...
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The topics are presented in viewgraph form and include the following; nuclear thermal propulsion (NTP) engine system analysis program development; nuclear thermal propulsion engine analysis capability requirements; team resources used to support NESS development; expanded liquid engine simulations (ELES) computer model; ELES verification examples; NESS program development evolution; past NTP ELES analysis code modifications and verifications; general NTP engine system features modeled by NESS;...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, NUCLEAR ENGINE FOR ROCKET VEHICLES,...
Extensive research activities were performed in the area of multidisciplinary modeling and simulation of aerospace vehicles that are relevant to NASA Dryden Flight Research Facility. The efforts involved theoretical development, computer coding, and debugging of the STARS code. New solution procedures were developed in such areas as structures, CFD, and graphics, among others. Furthermore, systems-oriented codes were developed for rendering the code truly multidisciplinary and rather automated...
Topics: NASA Technical Reports Server (NTRS), AEROELASTICITY, AEROSPACE VEHICLES, COMPUTATIONAL FLUID...
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NASA has been researching new technology and system concepts to meet the requirements of aeropropulsion for 21st Century aircraft. The air transportation for the new millennium will require revolutionary solutions to meet public demand for improving safety, reliability, environmental compatibility, and affordability. Whereas the turbine engine revolution will continue during the next two decades, several new revolutions are required to achieve the dream of an affordable, emissionless, and...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT ENGINES, PROPULSION, TURBINE ENGINES, TURBOFAN...
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This paper addresses the need to understand the physics and chemistry involved in propellant combustion processes in micro-scale combustors for propulsion systems on micro-spacecraft. These spacecraft are planned to have a mass less than 50 kilograms with attitude control estimated to be in the 10 milli-Newton thrust class. These combustors are anticipated to be manufactured using Micro Electrical Mechanical Systems (MEMS) technology and are expected to have diameters approaching the quenching...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL PROPULSION, SPACECRAFT PROPULSION, ROCKET ENGINES,...
A high-fidelity thermal model of the Mars Reconnaissance Orbiter was developed for use in an autonomous aerobraking simulation study. Response surface equations were derived from the high-fidelity thermal model and integrated into the autonomous aerobraking simulation software. The high-fidelity thermal model was developed using the Thermal Desktop software and used in all phases of the analysis. The use of Thermal Desktop exclusively, represented a change from previously developed aerobraking...
Topics: NASA Technical Reports Server (NTRS), AEROBRAKING, AUTONOMY, MARS RECONNAISSANCE ORBITER, THERMAL...
Stochastic radiation track structure codes are of great interest for space radiation studies and hadron therapy in medicine. These codes are used for a many purposes, notably for microdosimetry and DNA damage studies. In the last two decades, they were also used with the Independent Reaction Times (IRT) method in the simulation of chemical reactions, to calculate the yield of various radiolytic species produced during the radiolysis of water and in chemical dosimeters. Recently, we have...
Topics: NASA Technical Reports Server (NTRS), STOCHASTIC PROCESSES, GREEN'S FUNCTIONS, CHEMICAL REACTIONS,...
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This document represents the final report for the View Generated Database (VGD) project, NAS7-1066. It documents the work done on the project up to the point at which all project work was terminated due to lack of project funds. The VGD was to provide the capability to accurately represent any real-world object or scene as a computer model. Such models include both an accurate spatial/geometric representation of surfaces of the object or scene, as well as any surface detail present on the...
Topics: NASA Technical Reports Server (NTRS), COMPUTER GRAPHICS, COMPUTER PROGRAMS, COMPUTER VISION,...
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In earth observation or planetary exploration it is necessary to have more and, more autonomous systems, able to adapt to unpredictable situations. This imposes the use, in artificial systems, of new concepts in cognition, based on the fact that perception should not be separated from recognition and decision making levels. This means that low level signal processing (perception level) should interact with symbolic and high level processing (decision level). This paper is going to describe the...
Topics: NASA Technical Reports Server (NTRS), ACTIVE CONTROL, AUTONOMY, COGNITION, COMPUTER VISION, EARTH...
Virtualization provides the opportunity to continue to do "more with less"---more computing power with fewer physical boxes, thus reducing the overall hardware footprint, power and cooling requirements, software licenses, and their associated costs. This paper explores the tremendous advantages and any disadvantages of virtualization in all of the environments associated with software and systems development to operations flow. It includes the use and benefits of the Intelligent...
Topics: NASA Technical Reports Server (NTRS), CLIENT SERVER SYSTEMS, COMPUTER SYSTEMS PROGRAMS, PERFORMANCE...
Predictive methods/computer codes for the computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component are discussed. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of acoustic noise generated from a vibrating component, degradation in material properties of a composite laminate at use temperature, dynamic response of...
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC EXCITATION, ACOUSTIC FATIGUE, COMPOSITE STRUCTURES,...
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Experimental interferograms, schlieren, and shadow-graphs are routinely used for validating ideal- and real-gas computational fluid dynamics (CFD) codes. Interferograms are used for quantitative comparisons of integrated density. Schlieren and shadowgraphs are used for comparing the locations of flow field features; the types of flowfield features recorded in these images include shocks, shear layers, and expansion fans. By constructing images from flow field simulations, one-to-one comparisons...
Topics: NASA Technical Reports Server (NTRS), BALLISTIC RANGES, FLOW DISTRIBUTION, GAS FLOW, IDEAL GAS,...
The attitude control system (ACS) microprocessor development work spanned three main design areas: hardware and instruction set, ACS firmware, and hardware firmware verification testing. The processor hardware utilizes two parallel 4 bit microprocessors. The firmware includes data processing for five sensors, four attitude control laws, and telemetry and commands.
Topics: NASA Technical Reports Server (NTRS), ATTITUDE CONTROL, COMPUTERIZED SIMULATION, DATA PROCESSING...
Software engineering applications snapshots within the Space Station Freedom Program; software engineering and Ada training; software reuse; hierarchial command and control; program characteristics; integrated, international environments; software production, integration, and management; and integrated simulation environment are outlined in viewgraph format.
Topics: NASA Technical Reports Server (NTRS), ADA (PROGRAMMING LANGUAGE), COMPUTER PROGRAMMING,...
A computer simulation program which models a commercial short-haul aircraft operating in the civil air system was developed. The purpose of the program is to evaluate the effect of a given aircraft avionics capability on the ability of the aircraft to perform on-time carrier operations. The program outputs consist primarily of those quantities which can be used to determine direct operating costs. These include: (1) schedule reliability or delays, (2) repairs/replacements, (3) fuel consumption,...
Topics: NASA Technical Reports Server (NTRS), AIRLINE OPERATIONS, COMPUTERIZED SIMULATION, COST ANALYSIS,...
The development and validation of a spey engine model is described. An analysis of the dynamical interactions involved in the propulsion unit is presented. The model was reduced to contain only significant effects, and was used, in conjunction with flight data obtained from an augmentor wing jet STOL research aircraft, to develop initial estimates of parameters in the system. The theoretical background employed in estimating the parameters is outlined. The software package developed for...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT ENGINES, DYNAMIC CHARACTERISTICS, RESEARCH AIRCRAFT,...
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A portable analyzer which simulates in real time the complex nonlinear dynamics of horizontal axis wind energy systems was constructed. Math models for an aeroelastic rotor featuring nonlinear aerodynamic and inertial terms were implemented with high speed digital controllers and analog calculation. This model was combined with other math models of elastic supports, control systems, a power train and gimballed rotor kinematics. A stroboscopic display system graphically depicting distributed...
Topics: NASA Technical Reports Server (NTRS), AEROELASTICITY, AXES OF ROTATION, HORIZONTAL ORIENTATION,...
A simulation model was developed and programmed in three languages BASIC, PASCAL, and SLAM. Two of the programs are included in this report, the BASIC and the PASCAL language programs. SLAM is not supported by NASA/MSFC facilities and hence was not included. The statistical comparison of simulations of the same HOSC system configurations are in good agreement and are in agreement with the operational statistics of HOSC that were obtained. Three variations of the most recent HOSC configuration...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, DISTRIBUTED PROCESSING, STATISTICAL...
Aerodynamic noise from a landing gear in a uniform flow is computed using the Ffowcs Williams -Hawkings (FW-H) equation. The time accurate flow data on the surface is obtained using a finite volume flow solver on an unstructured and. The Ffowcs Williams-Hawkings equation is solved using surface integrals over the landing gear surface and over a permeable surface away from the landing gear. Two geometric configurations are tested in order to assess the impact of two lateral struts on the sound...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, UNIFORM FLOW, LANDING GEAR, DIRECTIVITY,...
A series of flight maneuvers were developed to cover the range of flight conditions and to define the repeatability and hysteresis of the sensors. Initial flights were made with two sensors at the + or - 68 percent span and 60 percent and 70 percent chord stations. The primary effort in simulation program development was to modify the LRC General Aviation Simulator (GAS) Fortran programs to allow execution on the MSU UNIVAC 1106. A simple model of the sensor-servo stall deterrent system was...
Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC STALLING, FLIGHT SIMULATORS, FLIGHT TESTS,...
Using a detailed simulation model of p(+)nn(+) and n(+)pp(+) indium phosphide (InP) homojunction solar cells, extensive parametric variation computer simulation runs were performed to aid in making near-optimum designs for these two solar cell configurations. The values of all the geometrical and material parameters corresponding to the near-optimal designs of both these configurations are presented. The results of parametric variation runs are presented for each configuration showing how the...
Topics: NASA Technical Reports Server (NTRS), HOMOJUNCTIONS, INDIUM PHOSPHIDES, SOLAR CELLS, COMPUTERIZED...
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It is found that the upper-bound limit for current collection in the case of strong magnetic field from the current is close to that given by the Parker-Murphy formula. This conclusion is consistent with the results obtained in laboratory experiments. This limit weakly depends on the shape of the wire. The adiabatic limit in this case will be easily surpassed due to strong magnetic field gradients near the separatrix. The calculations can be done using the kinetic equation in the drift...
Topics: NASA Technical Reports Server (NTRS), MAGNETIC FIELDS, CURRENTS, GEOMAGNETISM, PARTICLE MOTION,...
In this session, Session WP2, the discussion focuses on the following topics: Training Astronauts Using Three-Dimensional Visualizations of the International Space Station; Measurement and Validation of Bidirectional Reflectance of Shuttle and Space Station Materials for Computerized Lighting Models; Effects of Environmental Color on Mood and Performance of Astronauts in ISS; Psychophysical Measures of Motion and Orientation, Implications for Human Interface Design; and the Sopite Syndrome...
Topics: NASA Technical Reports Server (NTRS), AEROSPACE MEDICINE, MANNED SPACE FLIGHT, ASTRONAUT TRAINING,...
The results of the studies performed during the systems definition phase of POCCNET are presented. The concept of POCCNET as a system of standard POCCs is described and an analysis of system requirements is also included. Alternative systems concepts were evaluated as well as various methods for development of reliable reusable software. A number of POCC application areas, such as command management, on board computer support, and simulation were also studied. Other areas of investigation...
Topics: NASA Technical Reports Server (NTRS), GROUND STATIONS, PAYLOADS, SPACE SHUTTLE ORBITERS, COMPUTER...
The problem of Cartesian trajectory control of a closed-kinematic chain mechanism robot manipulator, recently built at CAIR to study the assembly of NASA hardware for the future Space Station, is considered. The study is performed by both computer simulation and experimentation for tracking of three different paths: a straight line, a sinusoid, and a circle. Linearization and pole placement methods are employed to design controller gains. Results show that the controllers are robust and there...
Topics: NASA Technical Reports Server (NTRS), CHAINS, COMPUTERIZED SIMULATION, CONTROL THEORY,...
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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,...
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Simulating Operation of a Planetary Rover Rover Analysis, Modeling, and Simulations (ROAMS) is a computer program that simulates the operation of a robotic vehicle (rover) engaged in exploration of a remote planet. ROAMS is a roverspecific extension of the DARTS and Dshell programs, described in prior NASA Tech Briefs articles, which afford capabilities for mathematical modeling of the dynamics of a spacecraft as a whole and of its instruments, actuators, and other subsystems. ROAMS...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, MATHEMATICAL MODELS, PLANETARY...
Detailed chemical process simulations are a useful tool in designing and optimizing complex systems and architectures for human life support. Dynamic and steady-state models of these systems help contrast the interactions of various operating parameters and hardware designs, which become extremely useful in trade-study analyses. NASA s Exploration Life Support technology development project recently made use of such models to compliment a series of tests on different waste water distillation...
Topics: NASA Technical Reports Server (NTRS), WATER RECLAMATION, SYSTEMS ENGINEERING, LIFE SUPPORT SYSTEMS,...
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A method to achieve man-in-the-control-loop simulation is presented. Emerging real-time dynamics simulation suggests a potential for creating an interactive design workstation with a human operator in the control loop. The recursive formulation for multibody dynamics simulation is studied to determine requirements for man-in-the-control-loop simulation. High speed computer graphics techniques provides realistic visual cues for the simulator. Backhoe and robot arm simulations are implemented to...
Topics: NASA Technical Reports Server (NTRS), COMPUTER GRAPHICS, COMPUTERIZED SIMULATION, FEEDBACK CONTROL,...
In order to understand the temporal relationship between H alpha and hard X-ray emission predicted by the nonthermal electron thick target model of impulsive-phase energy transport the time-dependent theoretical H alpha profiles were computed for the dynamic model atmospheres of Fisher, Canfield, and McClymont, which simulate the effects of an impulsively initiated power-law beam of electrons. On the basis of the physical analysis it was expected that a very rapid H alpha response to an...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC HEATING, ATMOSPHERIC MODELS, COMPUTERIZED...
The contamination effects due to outgassing from construction materials of the TAUVEX (Tel Aviv University UV Telescope) were evaluated using a combination of ground testing and computer simulations. Tests were performed from the material level of the system level including: (1) High sensitivity CVCM(10(exp -3 percent) measurements of critical materials. (2) Optical degradation measurements of samples specially contaminated by outgassing products at different contamination levels. (3) FTIR...
Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, CONTAMINATION, GROUND TESTS, HIGH...
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The development and testing of a real-time takeoff performance monitoring system is discussed. The algorithm is madeup of two segments: a pretakeoff segment and a real-time segment. One-time inputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate schedule performance data for that takeoff. The real-time segment uses the scheduled performance data generated in the pretakeoff segment, runway length data, and measured parameters to monitor...
Topics: NASA Technical Reports Server (NTRS), AIRCRAFT ENGINES, AIRCRAFT PERFORMANCE, ALGORITHMS,...
The paper presents a comparison of experimental noise data measured in flight on a two-engine business jet aircraft with Kulite microphones placed on the suction surface of the wing with computational results. Both a time-domain discontinuous Galerkin spectral method and a frequency-domain spectral element method are used to simulate the radiation of the dominant spinning mode from the engine and its reflection and scattering by the fuselage and the wing. Both methods are implemented in...
Topics: NASA Technical Reports Server (NTRS), NOISE PROPAGATION, ENGINE NOISE, WAVE SCATTERING, JET...
Several new space science mission concepts under development at NASA-GSFC for astronomy are intended to carry out synthetic imaging using Michelson interferometers or direct (Fizeau) imaging with sparse apertures. Examples of these mission concepts include the Stellar Imager (SI), the Space Infrared Interferometric Telescope (SPIRIT), the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and the Fourier-Kelvin Stellar Interferometer (FKSI). We have been developing computer-based...
Topics: NASA Technical Reports Server (NTRS), SPACE MISSIONS, COMPUTERIZED SIMULATION, MICHELSON...
Energy release rate is usually suggested as a quantifier for assessing structural damage tolerance. Computational prediction of energy release rate is based on composite mechanics with micro-stress level damage assessment, finite element structural analysis and damage progression tracking modules. This report examines several issues associated with energy release rates in composite structures as follows: Chapter I demonstrates computational simulation of an adhesively bonded composite joint and...
Topics: NASA Technical Reports Server (NTRS), TOLERANCES (MECHANICS), FRACTURES (MATERIALS), CRACKING...
Pb-2.2 wt% Sb alloy was directionally solidified in 1, 2, 3 and 7 mm diameter crucibles. Pb-Sb alloy presents a solutally unstable case. Under plane-front conditions, the resulting macrosegregation along the solidified length indicates that convection persists even in the 1 mm diameter crucible. Al-2 wt% Cu alloy was directionally solidified because this alloy was expected to be stable with respect to convection. Nevertheless, the resulting macrosegregation pattern and the microstructure in...
Topics: NASA Technical Reports Server (NTRS), CONVECTION, CRUCIBLES, DIRECTIONAL SOLIDIFICATION (CRYSTALS),...
The funded research projects under the Experimental Program to Stimulate Cooperative Research (EPSCoR) grant program and the student fellowship awards are summarized in this report. The projects include: 1) Crystallization of Dehydratase/DcoH: A Target in Lung Disease; 2) Measuring Velocity Profiles in Liquid Metals using an Ultrasonic Doppler Velocimeter; 3) Synthesis, Structure, and Properties of New Thermoelectric Materials; 4) Computational Determination of Structures and Reactivity of...
Topics: NASA Technical Reports Server (NTRS), DISEASES, VELOCITY DISTRIBUTION, LIQUID METALS, PHENOL...
As part of the National Cycle Program (NCP), a powerful new numerical solver has been developed to support the simulation of aeropropulsion systems. This software uses a hierarchical object-oriented design. It can provide steady-state and time-dependent solutions to nonlinear and even discontinuous problems typically encountered when aircraft and spacecraft propulsion systems are simulated. It also can handle constrained solutions, in which one or more factors may limit the behavior of the...
Topics: NASA Technical Reports Server (NTRS), PROPULSION SYSTEM CONFIGURATIONS, SPACECRAFT PROPULSION,...
The Propulsion IVHM Technology Experiment (PITEX) has been an on-going research effort conducted over several years. PITEX has developed and applied a model-based diagnostic system for the main propulsion system of the X-34 reusable launch vehicle, a space-launch technology demonstrator. The application was simulation-based using detailed models of the propulsion subsystem to generate nominal and failure scenarios during captive carry, which is the most safety-critical portion of the X-34...
Topics: NASA Technical Reports Server (NTRS), SYSTEMS HEALTH MONITORING, TECHNOLOGY UTILIZATION, SPACECRAFT...
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IMP (Integrated Mission Program) is a simulation language and code used to model present and future Earth, Moon, or Mars missions. The profile is user controlled through selection from a large menu of events and maneuvers. A Fehlberg 7/13 Runge-Kutta integrator with error and step size control is used to numerically integrate the differential equations of motion (DEQ) of three spacecraft, a main, a target, and an observer. Through selection, the DEQ's include guided thrust, oblate gravity,...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, COMPUTERIZED SIMULATION, DIFFERENTIAL...
Detailed chemical process simulations are a useful tool in designing and optimizing complex systems and architectures for human life support. Dynamic and steady-state models of these systems help contrast the interactions of various operating parameters and hardware designs, which become extremely useful in trade-study analyses. NASA?s Exploration Life Support technology development project recently made use of such models to compliment a series of tests on different waste water distillation...
Topics: NASA Technical Reports Server (NTRS), WATER RECLAMATION, COMPUTERIZED SIMULATION, CHEMICAL...
A method detects and isolates in-flight sensor, actuator, and component faults for advanced propulsion systems. In sharp contrast to many conventional methods, which deal with either sensor fault or component fault, but not both, this method considers sensor fault, actuator fault, and component fault under one systemic and unified framework. The proposed solution consists of two main components: a bank of real-time, nonlinear adaptive fault diagnostic estimators for residual generation, and a...
Topics: NASA Technical Reports Server (NTRS), ENGINE PARTS, NONLINEARITY, FAULT DETECTION, ONBOARD...
The purpose of this paper is to look for links in a virtual trainee's interest and self-efficacy in a simulated event as it relates to their previous self-reported technical skill level. Ultimately, the idea would be to provide the right amount of support at the right place at the right time to set the conditions for maximum transfer of the skill sets to the work place. An anecdotal recap of a recent experiment of a medium-scale training event produced in a virtual world will provide examples...
Topics: NASA Technical Reports Server (NTRS), VIRTUAL REALITY, EDUCATION, COMPUTERIZED SIMULATION, TEAMS,...
A time accurate, general purpose, adaptive grid method is developed that is suitable for multidimensional steady and unsteady numerical simulations. The grid point movement is performed in a manner that generates smooth grids which resolve the severe solution gradients and the sharp transitions in the solution gradients. The temporal coupling of the adaptive grid and the PDE solver is performed with a grid prediction correction method that is simple to implement and ensures the time accuracy of...
Topics: NASA Technical Reports Server (NTRS), COMPUTATIONAL GRIDS, COMPUTERIZED SIMULATION, GRID GENERATION...
The display under investigation, is a tunnel display for the four-dimensional commercial aircraft approach-to-landing under instrument flight rules. It is investigated whether more complex predictive information such as a three-dimensional perspective vehicle symbol, predicting the future vehicle position as well as future vehicle attitude angles, contributes to a better system response, and suitable predictor laws for the predictor motions, are formulated. Methods for utilizing the predictor...
Topics: NASA Technical Reports Server (NTRS), APPROACH INDICATORS, COMPUTERIZED SIMULATION, DISPLAY...