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The relationship between multivariable zeros and inverse systems was explored. A definition of zero module is given in such a way that it is basis independent. The existence of essential right and left inverses were established. The way in which the abstract zero module captured previous definitions of multivariable zeros is explained and examples are presented.
Topics: NASA Technical Reports Server (NTRS), FEEDBACK CONTROL, MATHEMATICAL MODELS, DYNAMIC RESPONSE,...
A mathematical analysis of the tradeoffs and requirements was performed to develop an improved array design which will give stronger returns at lower elevation angles and reduce pulse spread in the return. It was determined that a zenith angle of 75deg can be obtained with an array with an area of 0.28 sq m, if the array is shaped on the surface of a 45 deg cone whose axis is coincident to the satellite axis. The total weight of the truncated pyramid array with 270 cube corners is calculated to...
Topics: NASA Technical Reports Server (NTRS), GEOS 3 SATELLITE, LASERS, REFLECTORS, MATHEMATICAL MODELS,...
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System and method for providing surveillance of an asset comprised of numerically fitting at least one mathematical model to obtained residual data correlative to asset operation; storing at least one mathematical model in a memory; obtaining a current set of signal data from the asset; retrieving at least one mathematical model from the memory, using the retrieved mathematical model in a sequential hypothesis test for determining if the current set of signal data is indicative of a fault...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, SURVEILLANCE, PATENTS, Bickford, Randall...
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...
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by NASA Technical Reports Server (NTRS)
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The first part of this presentation is a tutorial level introduction to the principles of genetic search and models of simple genetic algorithms. The second half covers the combination of genetic algorithms with local search methods to produce hybrid genetic algorithms. Hybrid algorithms can be modeled within the existing theoretical framework developed for simple genetic algorithms. An application of a hybrid to geometric model matching is given. The hybrid algorithm yields results that...
Topics: NASA Technical Reports Server (NTRS), GENETIC ALGORITHMS, SEARCH PROFILES, POPULATION THEORY,...
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by NASA Technical Reports Server (NTRS)
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Mathematical and algorithmical techniques for solution of problems in satellite dynamics were developed, along with solutions to satellite orbit motion. Dynamical analysis of shuttle on-orbit operations were conducted. Computer software routines for use in shuttle mission planning were developed and analyzed, while mathematical models of atmospheric density were formulated.
Topics: NASA Technical Reports Server (NTRS), ORBIT CALCULATION, REPORTS, SATELLITE ORBITS, ALGORITHMS,...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, RELIABILITY, MATHEMATICAL...
Four possible estimators are investigated for the monitoring of crustal deformations from a combination of repeated baseline length measurements and adopted geophysical models, particularly an absolute motion plate model. The first estimator is an extension of the familiar free adjustment. The next two are Bayesian type estimators, one weak and one strong. Finally, a weighted constraint estimator is presented. The properties of these four estimators are outlined and their physical...
Topics: NASA Technical Reports Server (NTRS), DEFORMATION, EARTH CRUST, GEOPHYSICS, MATHEMATICAL MODELS,...
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The state-of-the-art of turbulent flow computation is surveyed. The formulations were generalized to increase the range of their applicability, and the excitement of current debate on equation models was brought into the review. Some new ideas on the modeling of the pressure-strain term in the Reynolds stress equations are also suggested.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, TURBULENT FLOW, STRESSES, Reynolds, W. C.
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,...
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by NASA Technical Reports Server (NTRS)
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Since the original chapter, we briefly review two calculational methods used for basic applications in autoionization of few body systems: (a) complex rotation and (b) a pseudopotential method. Complex rotation, briefly mentioned above, has been extensively applied with great accuracy. Two additional basic systems to be mentioned here are H(sup -) and Ps(sup -) (Ps=positronium). In complex rotation the particle distances are multiplied by the common phase factor given.
Topics: NASA Technical Reports Server (NTRS), AUTOIONIZATION, MATHEMATICAL MODELS, HAMILTONIAN FUNCTIONS,...
This report covers technical progress during the third quarter of the second year of NASA Sun-Earth Connections Theory Program (SECTP) contract 'The Structure and Dynamics of the Solar Corona and Inner Heliosphere,' NAS5-99188, between NASA and Science Applications International Corporation, and covers the period February 16, 2001 to May 15, 2001. Under this contract SAIC and the University of California, Irvine (UCI) have conducted research into theoretical modeling of active regions, the...
Topics: NASA Technical Reports Server (NTRS), MAGNETOHYDRODYNAMICS, SOLAR PHYSICS, HELIOSPHERE, SOLAR...
The first-order model of acoustic emission from fiber composites, based on filament breaking rates, is cast into a normalized form useful for correlating experimental data. The general features of the normalized model are shown.
Topics: NASA Technical Reports Server (NTRS), COMPOSITE MATERIALS, MATHEMATICAL MODELS, SOUND WAVES,...
A common feature of several pole placement techniques is discussed and the use of a dyadic feedback matrix is presented. The limitation of this design is examined and a design involving output feedback matrices of Rank greater than one is developed as a logical extension of the dyadic feedback design. An example is presented to illustrate the design procedure.
Topics: NASA Technical Reports Server (NTRS), FEEDBACK, RANK TESTS, EIGENVALUES, MATHEMATICAL MODELS,...
An annotated compendium on mathematical modeling of mammal thermoregulation systems is presented. Author abstracts, tables containing the more used mathematical models, solutions to these models, and each thermoregulation mechanism considered are included.
Topics: NASA Technical Reports Server (NTRS), HEAT TRANSFER, MAMMALS, MATHEMATICAL MODELS,...
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This talk will focus on the status of current understanding (not a historical review) as regards modeling nitrogen oxides (NOy) in the lower stratosphere (LS). The presentation will be organized around three major areas of process understanding: 1) NOy sources, sinks, and transport to the LS, 2) NOy species partitioning, and 3) polar multiphase processes. In each area, process topics will be identified with an estimate of the degree of confidence associated with their representation in...
Topics: NASA Technical Reports Server (NTRS), NITROGEN OXIDES, STRATOSPHERE, MATHEMATICAL MODELS, SINKS,...
The detection of cavity radiation with the detector placed outside the cavity is studied. Each leaked photon has a certain probability of propagating away without being detected. It is viewed as a continuous quantum measurement in which the density matrix is continuously revised according to the readout of the detector. The concept of pseudomaster equation for the no-count process is introduced; its solution leads to the discovery of the superoperator for the same process. It has the potential...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, PHOTOMETERS, QUANTUM THEORY, PHOTONS,...
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Pre-launch algorithm development & post-launch product evaluation: The GPM GV paradigm moves beyond traditional direct validation/comparison activities by incorporating improved algorithm physics & model applications (end-to-end validation) in the validation process. Three approaches: 1) National Network (surface): Operational networks to identify and resolve first order discrepancies (e.g., bias) between satellite and ground-based precipitation estimates. 2) Physical Process (vertical...
Topics: NASA Technical Reports Server (NTRS), CLOUD PHYSICS, ALGORITHMS, LAUNCHING, BIAS, MATHEMATICAL...
The modeling of communication receivers is described at both the circuit detail level and at the block level. The largest effort was devoted to developing new models at the block modeling level. The available effort did not permit full development of all of the block modeling concepts envisioned, but idealized blocks were developed for signal sources, a variety of filters, limiters, amplifiers, mixers, and demodulators. These blocks were organized into an operational computer simulation of...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, TELECOMMUNICATION, CIRCUITS, RADIO...
The research at the Systems and Control Laboratory is reported. Topics discussed include: response characteristics of laminar fluidic amplifiers, power amplification with a vortex valve, pulse-supply-mode fluidics, speed control system employing a jet pipe valve, and the fluidics reference center.
Topics: NASA Technical Reports Server (NTRS), FLUID AMPLIFIERS, FLUIDICS, MATHEMATICAL MODELS, RESEARCH AND...
A method that involves the use of fictitious plate elements denoted b ridge plates has been developed for representing the stiffnesses of fillets in finiteelement calculations of deflections, stresses, and strains in structures. The bridge plates of the present method are re duced-order models of fillets that do not yield accurate stresses wi thin fillets but do make it possible to accurately calculate the dyna mic characteristics of the structure and to approximate the effects of fillets on...
Topics: NASA Technical Reports Server (NTRS), FILLETS, FINITE ELEMENT METHOD, APPROXIMATION, MATHEMATICAL...
Over the past two decades, NASA Lewis Research Center's in-house efforts in analytical modeling for advanced composites have yielded several computational predictive tools. These are, in general, based on simplified micromechanics equations. During the last 3 years, our efforts have been directed primarily toward developing prediction tools for high temperature ceramic matrix composite (CMC's) materials. These materials are being considered for High Speed Research program applications,...
Topics: NASA Technical Reports Server (NTRS), INFORMATION SYSTEMS, MATHEMATICAL MODELS, MICROMECHANICS,...
The thermal model for transverse heat flow of having single filament in a unit cell is extended. In this model, we proposed that two circular filaments in a unit cell of square packing array and obtained the transverse thermal conductivity of an unidirectional material.
Topics: NASA Technical Reports Server (NTRS), COMPOSITE MATERIALS, THERMAL ANALYSIS, MATHEMATICAL MODELS,...
A method of approximating a scalar function of n independent variables (where n is a positive integer) to arbitrary accuracy has been developed. This method is expected to be attractive for use in engineering computations in which it is necessary to link global models with local ones or in which it is necessary to interpolate noiseless tabular data that have been computed from analytic functions or numerical models in n-dimensional spaces of design parameters.
Topics: NASA Technical Reports Server (NTRS), ANALYTIC FUNCTIONS, INDEPENDENT VARIABLES, SCALARS,...
Ridge, Marquardt's generalized inverse, shrunken, and principal components estimators are discussed in terms of the objectives of point estimation of parameters, estimation of the predictive regression function, and hypothesis testing. It is found that as the normal equations approach singularity, more consideration must be given to estimable functions of the parameters as opposed to estimation of the full parameter vector; that biased estimators all introduce constraints on the parameter...
Topics: NASA Technical Reports Server (NTRS), ESTIMATING, LINEAR PREDICTION, REGRESSION ANALYSIS,...
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Aspects of an attitude control system were studied and developed for a large space base that is structurally flexible and whose mass properties change rather dramatically during its orbital lifetime. Topics of discussion include the following: (1) space base orbital pointing and maneuvering; (2) angular momentum sizing of actuators; (3) momentum desaturation selection and sizing; (4) multilevel control technique applied to configuration one; (5) one-dimensional model simulation; (6) N-body...
Topics: NASA Technical Reports Server (NTRS), ATTITUDE CONTROL, SPACE BASES, SPACE STATIONS, ANGULAR...
Establishing the geometry of foam cells is useful in developing microstructure-based acoustic and structural models. Since experimental data on the geometry of the foam cells are limited, most modeling efforts use the three-dimensional, space-filling Kelvin tetrakaidecahedron. The validity of this assumption is investigated in the present paper. Several FeCrAlY foams with relative densities varying between 3 and 15 percent and cells per mm (c.p.mm.) varying between 0.2 and 3.9 c.p.mm. were...
Topics: NASA Technical Reports Server (NTRS), FOAMS, ACOUSTIC PROPERTIES, MICROSTRUCTURE, MATHEMATICAL...
Manual revisions are presented for the modified and expanded STEAP series. The STEAP 2 is composed of three independent but related programs: NOMAL for the generation of n-body nominal trajectories performing a number of deterministic guidance events; ERRAN for the linear error analysis and generalized covariance analysis along specific targeted trajectories; and SIMUL for testing the mathematical models used in the navigation and guidance process. The analytic manual provides general problem...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, MANUALS, SPACECRAFT...
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Bayesian surface modeling from images requires modeling both the surface and the image generation process, in order to optimize the models by comparing actual and generated images. Thus it differs greatly, both conceptually and in computational difficulty, from conventional stereo surface recovery techniques. But it offers the possibility of using any number of images, taken under quite different conditions, and by different instruments that provide independent and often complementary...
Topics: NASA Technical Reports Server (NTRS), BAYES THEOREM, MULTISENSOR FUSION, IMAGERY, FAILURE,...
For abstract, see N72-17902.
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, MANUALS, SPACECRAFT...
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The threshold region of the double-photoionization cross section is of particular interest because both ejected electrons move slowly in the Coulomb field of the residual ion. Near threshold both electrons have time to interact with each other and with the residual ion. Also, different theoretical models compete to describe the double-photoionization cross section in the threshold region. We have investigated that cross section for lithium and beryllium and have analyzed our data with respect...
Topics: NASA Technical Reports Server (NTRS), PHOTOIONIZATION, BERYLLIUM, LITHIUM, ELECTRONS, MATHEMATICAL...
While the response surface method is an effective method in engineering optimization, its accuracy is often affected by the use of limited amount of data points for model construction. In this chapter, the issues related to the accuracy of the RS approximations and possible ways of improving the RS model using appropriate treatments, including the iteratively re-weighted least square (IRLS) technique and the radial-basis neural networks, are investigated. A main interest is to identify ways to...
Topics: NASA Technical Reports Server (NTRS), PROPULSION, LEAST SQUARES METHOD, MATHEMATICAL MODELS, NEURAL...
This paper evaluates how quickly students can be trained to construct useful discrete-event simulation models using Excel The typical supply chain used by many large national retailers is described, and an Excel-based simulation model is constructed of it The set of programming and simulation skills required for development of that model are then determined we conclude that six hours of training are required to teach the skills to MBA students . The simulation presented here contains all...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, SIMULATION, SPREADSHEETS, EDUCATION,...
This slide presentation discusses a mathematical model to monitor particle fallout in a cleanroom. "Cleanliness levels" do not lead to increases with regards to cleanroom type or time because the levels are not linear. Activity level, impacts the cleanroom class. The numerical method presented leads to a simple Class-hour formulation, that allows for dynamic monitoring of the particle using a standard air particle counter.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, CLEAN ROOMS, PARTICLES, RADIATION...
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An introduction to airship performance is presented. Static lift equations are shown which, when combined with power requirements for conventional airships, allow parametric studies of range, payload, speed and airship size. It is shown that very large airships are required to attain reasonable speeds at transoceanic ranges.
Topics: NASA Technical Reports Server (NTRS), AIRSHIPS, TECHNOLOGY ASSESSMENT, LIFT, MATHEMATICAL MODELS,...
Because conventional optimal linear regulator theory results in a controller which requires the capability of measuring and/or estimating the entire state vector, it is of interest to consider procedures for computing controls which are restricted to be linear feedback functions of a lower dimensional output vector and which take into account the presence of measurement noise and process uncertainty. To this effect a stochastic linear model has been developed that accounts for process parameter...
Topics: NASA Technical Reports Server (NTRS), FEEDBACK CONTROL, LINEAR SYSTEMS, STOCHASTIC PROCESSES,...
The Fission Power System (FPS) project is developing a Technology Demonstration Unit (TDU) to verify the performance and functionality of a subscale version of the FPS reference concept in a relevant environment, and to verify component and system models. As hardware is developed for the TDU, component and system models must be refined to include the details of specific component designs. This paper describes the development of a Sage-based pseudo-steady-state Stirling convertor model and its...
Topics: NASA Technical Reports Server (NTRS), FISSION, STIRLING CYCLE, MATHEMATICAL MODELS, STEADY STATE,...
The zonal temporal averages of albedos at the top of the atmosphere were considered as a function of the length of the day. The length of the day were used to determine the average daily values of mu sub 0(=Cos of the solar zenith angle, theta sub 0). Polynominal fits of the slope and intercept functions of A sub s (cloud-free albedo) and A sub c(cloud albedo) as function of Cos theta sub 0 were obtained by using the sample values of albedo corresponding to solar zenith angles from 0 to 90 deg...
Topics: NASA Technical Reports Server (NTRS), ALBEDO, CLOUD COVER, COMPUTATION, MATHEMATICAL MODELS, SOLAR...
Syntonics LLC developed a prototype micro-Ultra Stable Oscillator (micro-USO) under a Space Base Technology Grant (NAGS-10395). Syntonics conducted the micro-USO Program in two phases. In Phase I, we developed a set of verified analytical models (including thermal, electrical, and control models) for a baseline USO, conducted a series of six technology studies, and built three approx.9OOg prototype units. These prototypes provided a tool for evaluating competing design topologies. In Phase II...
Topics: NASA Technical Reports Server (NTRS), OSCILLATORS, TEMPERATURE CONTROL, SPACE BASES, MATHEMATICAL...
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A document discusses a new algorithm for generating higher-order dependencies for diagnostic and sensor placement analysis when a system is described with a causal modeling framework. This innovation will be used in diagnostic and sensor optimization and analysis tools. Fault detection, diagnosis, and prognosis are essential tasks in the operation of autonomous spacecraft, instruments, and in-situ platforms. This algorithm will serve as a power tool for technologies that satisfy a key...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, SENSORS, MATHEMATICAL MODELS, POSITION...
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The value of a previously classified image is discussed with the use of spectral and temporal information. A probability theory is presented of a signal X, belonging to class pi sub i.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, PATTERN RECOGNITION, ERROR ANALYSIS, MATHEMATICAL...
A closed system of algebraic and common differential equations solved by computer is investigated. It includes equations which describe the activity pattern of the respiratory center, the phrenic nerve, the thrust produced by the diaphragm as a function of the lung volume and discharge frequency of the phrenic nerve, as well as certain relations of the lung stretch receptors and chemoreceptors on various lung and blood characteristics, equations for lung biomechanics, pulmonary blood flow,...
Topics: NASA Technical Reports Server (NTRS), HUMAN BEINGS, MATHEMATICAL MODELS, RESPIRATORY PHYSIOLOGY,...
We present an algorithm for model checking temporal-epistemic properties of multi-agent systems, expressed in the formalism of interpreted systems. We first introduce a technique for the translation of interpreted systems into boolean formulae, and then present a model-checking algorithm based on this translation. The algorithm is based on OBDD's, as they offer a compact and efficient representation for boolean formulae.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, BOOLEAN ALGEBRA, FORMALISM, TRANSLATING,...
A mathematical reliability model is established for a reconfigurable fault tolerant avionic computer system utilizing state-of-the-art computers. System reliability is studied in light of the coverage probabilities associated with the first and second independent hardware failures. Coverage models are presented as a function of detection, isolation, and recovery probabilities. Upper and lower bonds are established for the coverage probabilities and the method for computing values for the...
Topics: NASA Technical Reports Server (NTRS), COMPUTERS, MATHEMATICAL MODELS, RELIABILITY, FAULTS, SYSTEMS...
We investigate the process of subclustering in the hierarchical model of galaxy formation. We construct density field around peaks of density fluctuations using the path integral method and investigate their nature.
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL MODELS, GALACTIC CLUSTERS, GALACTIC EVOLUTION,...
It has become more and more evident that many difficulties encountered in the course of aircraft flutter analyses can be traced to strong localized nonlinearities in the control mechanisms. To cope with these problems, more reliable mathematical models paying special attention to control system nonlinearities were established by means of modified ground vibration test procedures in combination with suitably adapted modal synthesis approaches. Three different concepts are presented.
Topics: NASA Technical Reports Server (NTRS), FLUTTER, LIGHT AIRCRAFT, FLIGHT CONTROL, MATHEMATICAL MODELS,...
The approach and organization of the study to develop a high level computer programming language and a program library are presented. The algorithm and problem modeling analyses are summarized. The approach used to identify and specify the capabilities required in the basic language is described. Results of the analyses used to define specifications for the scheduling module library are presented.
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, PROGRAMMING LANGUAGES, SCHEDULING, COMPUTER...
Topics: NASA Technical Reports Server (NTRS), RESEARCH PROJECTS, URBAN PLANNING, URBAN TRANSPORTATION,...
The Rodon model-based diagnosis shell was applied to a breadboard test-bed, modeling an automated power distribution system. The constraint-based modeling paradigm and diagnostic algorithm were found to adequately represent the selected set of test scenarios.
Topics: NASA Technical Reports Server (NTRS), BREADBOARD MODELS, MATHEMATICAL MODELS, ALGORITHMS,...
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Engineering analyses performed on the Atmospheric Cloud Physics (ACPL) Science Simulator expansion chamber and associated thermal control/conditioning system are reported. Analyses were made to develop a verified thermal model and to perform parametric thermal investigations to evaluate systems performance characteristics. Thermal network representations of solid components and the complete fluid conditioning system were solved simultaneously using the Systems Improved Numerical Differencing...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC CHEMISTRY, CLOUD PHYSICS, MATHEMATICAL MODELS,...
For abstract, see N72-17902.
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, MANUALS, SPACECRAFT...
The role of potential barrier formation in spacecraft charging at geosynchronous orbit is discussed. The evidence for, and understanding of, spacecraft charging and its hazards to spacecraft operation in the early 1970's are summarized. Theoretical and experimental advances which have changed the basic understanding of the role of barrier formation in charging phenomenology are described. Potential barriers are found to play a fundamental role in the dynamics of spacecraft charging. The...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC POTENTIAL, GEOSYNCHRONOUS ORBITS, SPACECRAFT...
The recent fusion of decades of advancements in mathematical models, numerical algorithms and curve fitting techniques marked the beginning of a new era in the science of simulation. It is becoming indispensable to the study of rockets and aerospace analysis. In pneumatic system, which is the main focus of this paper, particular emphasis will be placed on the efforts of compressible flow in Attitude Control System of sounding rocket.
Topics: NASA Technical Reports Server (NTRS), SOUNDING ROCKETS, ATTITUDE CONTROL, MATHEMATICAL MODELS,...
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Our UV/VIS work concentrates on black hole X-ray nova. These objects consist of two stars in close orbit, one of which we believe is a black hole - our goal is to SHOW that one is a black hole. In order to reach this goal we carry out observations in the Optical, UV, IR and X-ray bands, and compare the observations to theoretical models. In the past year, our UV/VIS grant has provided partial support (mainly travel funds and page charges) for work we have done on X-ray nova containing black...
Topics: NASA Technical Reports Server (NTRS), HORIZON, BLACK HOLES (ASTRONOMY), NEUTRON STARS, X RAYS,...
A two-step ensemble recentering Kalman filter (ERKF) analysis scheme is introduced. The algorithm consists of a recentering step followed by an ensemble Kalman filter (EnKF) analysis step. The recentering step is formulated such as to adjust the prior distribution of an ensemble of model states so that the deviations of individual samples from the sample mean are unchanged but the original sample mean is shifted to the prior position of the most likely particle, where the likelihood of each...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, KALMAN FILTERS, TEMPERATURE PROFILES, DATA...
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Mathematical models of the coupled global systems of sedimentary reservoirs and fluxes are used to infer variations in reservoir sizes and rates of sedimentation over periods of hundreds of millions of years. Perhaps most interesting is the coupled sulfide/sulfate carbon/carbonate system that controls global oxygen and carbon dioxide production and consumption is discussed.
Topics: NASA Technical Reports Server (NTRS), CARBON DIOXIDE, GEOLOGY, MATHEMATICAL MODELS, RESERVOIRS,...
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Under this contract SAIC, the University of California, Irvine (UCI), and the Jet Propulsion Laboratory (JPL), have conducted research into theoretical modeling of active regions, the solar corona, and the inner heliosphere, using the MHD model. During the period covered by this report we have published 17 articles in the scientific literature. These publications are listed in Section 4 of this report. In the Appendix we have attached reprints of selected articles.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, SOLAR CORONA, MAGNETOHYDRODYNAMICS, JET...
This presentation covers research being performed on computational nanotechnology, carbon nanotubes and fullerenes at the NASA Ames Research Center. Topics cover include: nanomechanics of nanomaterials, nanotubes and composite materials, molecular electronics with nanotube junctions, kinky chemistry, and nanotechnology for solid-state quantum computers using fullerenes.
Topics: NASA Technical Reports Server (NTRS), NANOTECHNOLOGY, CARBON NANOTUBES, NANOSTRUCTURE...
Addition of an inverted lifting device to a simple balloon probe is shown to make possible low-altitude entry to tornado cores with easier launch conditions than for the simple balloon probe. Balloon-lifter combinations are particularly suitable for penetration of tornadoes with average to strong circulation, but tornadoes of less than average circulation which are inaccessible to simple balloon probes become accessible. The increased launch radius which is needed for access to tornadoes over a...
Topics: NASA Technical Reports Server (NTRS), BALLOONS, LIFT DEVICES, TORNADOES, ATMOSPHERIC CIRCULATION,...
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Some of the basic ideas associated with the detection of abrupt changes in dynamic systems are presented. Multiple filter-based techniques and residual-based method and the multiple model and generalized likelihood ratio methods are considered. Issues such as the effect of unknown onset time on algorithm complexity and structure and robustness to model uncertainty are discussed.
Topics: NASA Technical Reports Server (NTRS), DYNAMIC CHARACTERISTICS, LIKELIHOOD RATIO, ROBUSTNESS...
This paper presents a simple method for performing elastic R-curve instability calculations. For a single material-structure combination, the calculations can be done on some pocket calculators. On microcomputers and larger, it permits the development of a comprehensive program having libraries of driving force equations for different configurations and R-curve model equations for different materials. The paper also presents several model equations for fitting to experimental R-curve data, both...
Topics: NASA Technical Reports Server (NTRS), CURVES, J INTEGRAL, MATHEMATICAL MODELS, STABILITY, DATA...
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Tensor model order reduction, recursive tensor model identification, input design for tensor model identification, software development for nonlinear feedback control laws based upon tensors, and development of the CATNAP software package for tensor modeling, identification and simulation were studied. The last of these are discussed.
Topics: NASA Technical Reports Server (NTRS), FEEDBACK CONTROL, JET ENGINES, TENSORS, COMPUTER PROGRAMS,...
A technique for estimating transfer functions in partial fraction expansion form from frequency response data for a high-order system is presented. The problem formulation avoids many of the numerical difficulties associated with high-order polynomials and has the advantage of having the option to fix the camping and frequency of a mode, if known, during the estimation process. The resulting transfer function(s) may be converted to Jordan-Form time domain equations directly. During the...
Topics: NASA Technical Reports Server (NTRS), FREQUENCY RESPONSE, MATHEMATICAL MODELS, OPTIMIZATION,...
The circulation functional relative to two adjacent lifting sections is studied for two cases. In the first case we consider two adjacent circles. The circulation is computed as a function of the displacement of the secondary circle along the axis joining the two centers and of the angle of attack of the secondary circle, The gradient of such functional is computed by deriving a set of elliptic functions with respect both to their argument and to their Period. In the second case studied, we...
Topics: NASA Technical Reports Server (NTRS), CIRCLES (GEOMETRY), ELLIPTIC FUNCTIONS, MANIFOLDS...
Quantum macroscopic motions are investigated in the scheme consisting of N-number of harmonic oscillators in terms of ultra-power representations of nonstandard analysis. Decoherence is derived from the large internal degrees of freedom of macroscopic matters.
Topics: NASA Technical Reports Server (NTRS), QUANTUM MECHANICS, HARMONIC OSCILLATORS, DEGREES OF FREEDOM,...
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A report is presented describing the research conducted on five phases: (1) ignition of fuel drops by a shock wave and passage of a shock wave over a burning drop, (2) the energy release pattern of a two-phase detonation with controlled drop sizes, (3) the attenuation of shock and detonation waves passing over an acoustic liner, (4) experimental and theoretical studies of film detonations, and (5) a simplified analytical model of a rotating two-phase detonation wave in a rocket motor.
Topics: NASA Technical Reports Server (NTRS), DETONATION, SHOCK WAVES, MATHEMATICAL MODELS, ROCKET ENGINES,...
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Numerical model studies have suggested that the ongoing global warming will likely affect tropical cyclone activity. But so far little observed evidence has been detected to support the projected future changes. Using satellite-supported best-track data from 1965 to 2003, we show for the first time that over the past four decades the two prevailing typhoon tracks in the western North Pacific (WNP) have shifted westward significantly; the typhoon activity over the South China Sea has...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, GLOBAL WARMING, TYPHOONS, ASIA, MARINE...
An improved mathematical model has been developed of the time dependence of buildup or decay of electric charge in a high-resistivity (nominally insulating) material. The model is intended primarily for use in extracting the DC electrical resistivity of such a material from voltage -vs.- current measurements performed repeatedly on a sample of the material over a time comparable to the longest characteristic times (typically of the order of months) that govern the evolution of relevant...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC CHARGE, ELECTRICAL RESISTIVITY, MATHEMATICAL MODELS,...
A differential equation proposed by H. Lashinsky to describe the nonlinear solution of aperiodic instabilities is investigated. Oscillatory and nonoscillatory solutions are discussed and a numerical integration is presented.
Topics: NASA Technical Reports Server (NTRS), DIFFERENTIAL EQUATIONS, NONLINEARITY, STABILITY, MATHEMATICAL...
The purpose of this grant was to develop a theoretical understanding of the processes by which open magnetic flux undergoes large-scale transport in the solar corona, and to use this understanding to develop a predictive model for the heliospheric magnetic field, the configuration for which is determined by such motions.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, HELIOSPHERE, SOLAR CORONA, MAGNETIC...
A concise mathematical model is developed for surface fatigue life of low-contact-ratio spur gears. The expected fatigue life of the pinion, gear, or gear sets may be calculated from the model. An equation for the dynamic capacity of the gear set was also derived in terms of the transmitted tangential tooth load which will give a 10-percent fatigue life of one million pinion revolutions. The theoretical life was compared with experimental data for a set of VAR AISI 9310 gears operating at a...
Topics: NASA Technical Reports Server (NTRS), FATIGUE LIFE, GEARS, MATHEMATICAL MODELS, FATIGUE TESTS,...
The operation of a subsonic, Gerdien condenser probe for in situ measurements of the mesosphere and stratosphere is presented. The inclusion of a flashing Lyman alpha ultraviolet source provides an artifically produced ionization of particular constituents. Detailed theory of operation is presented and the data results from two flights are shown. A great deal of fine structure in mobility is observed due to the presence of various hydrated positive ions. The effect of the Lyman alpha source in...
Topics: NASA Technical Reports Server (NTRS), MESOSPHERE, STRATOSPHERE, ION DENSITY (CONCENTRATION), LYMAN...
An examination of animal response to CO is studied along with potential models for extrapolating animal test data to humans. The best models for extrapolating data were found to be the Probit and Weibull models.
Topics: NASA Technical Reports Server (NTRS), BEHAVIOR, CARBON DIOXIDE, PHYSIOLOGICAL RESPONSES,...
The characteristics of a proposed low-boom aircraft concept cannot be adequately assessed unless it is given an extensive, time-consuming, mission-performance, and sonic-boom analyses. So, it would be useful to have a method for performing a quick first-order sonic-boom and mission-range analysis. The evaluation method outlined in this report has the attributes of being both fast and reasonably accurate. It can also be used as a design tool to estimate the sonic-boom ground overpressures,...
Topics: NASA Technical Reports Server (NTRS), SONIC BOOMS, COMPUTER PROGRAMS, MACH NUMBER, MATHEMATICAL...
This paper provides an elementary tutorial overview of Bayesian inference and its potential for application in aerospace experimentation in general and wind tunnel testing in particular. Bayes Theorem is reviewed and examples are provided to illustrate how it can be applied to objectively revise prior knowledge by incorporating insights subsequently obtained from additional observations, resulting in new (posterior) knowledge that combines information from both sources. A logical merger of...
Topics: NASA Technical Reports Server (NTRS), BAYES THEOREM, EXPERIMENT DESIGN, WIND TUNNEL TESTS,...
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The one-dimensional classical scalar string equation which involves linearization about a horizontal reference or equilibrium position is derived. We then derive a model for small motion about a nonhorizontal reference. The implications of our findings to modeling of flexible antenna surfaces such as that in the Maypole Hoop/Column antenna are discussed.
Topics: NASA Technical Reports Server (NTRS), FLEXIBLE BODIES, LINEARIZATION, SURFACE PROPERTIES, ANTENNA...
MULTIVAR is a FORTRAN 77 computer program that fits one of the members of a set of six multivariable mathematical models (five of which are nonlinear) to a multivariable set of data. The inputs to MULTIVAR include the data for the independent and dependent variables plus the user s choice of one of the models, one of the three optimization engines, and convergence criteria. By use of the chosen optimization engine, MULTIVAR finds values for the parameters of the chosen model so as to minimize...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, MATHEMATICAL MODELS, NONLINEARITY,...
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by NASA Technical Reports Server (NTRS)
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The goal was to develop analytic methods to prove performance properties and to measure reliability properties of software. Charts on software reliability studies and on a software error experiment are given.
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERRORS, RELIABILITY, SOFTWARE ENGINEERING,...
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Programable system introduces correction factor to compensate for detector deviation from square-law response. If detector output voltage is V, the corrected output voltage is determined as V corrected = aV squared where 'a' is correction factor. Factor is determined and used automatically with digital computer techniques.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, MICROWAVE ANTENNAS, RADIATION COUNTERS,...
A geometric representation scheme called the B-spline cylinder, which consists of interpolation between pairs of uniform periodic cubic B-spline curves is discussed. This approach carries a number of interesting implications. For one, a single relatively simple database schema can be used to represent a reasonably large class of objects, since the spline representation is flexible enough to allow a large domain of representable objects at very little cost in data complexity. The model is thus...
Topics: NASA Technical Reports Server (NTRS), COMPUTER AIDED DESIGN, COMPUTER GRAPHICS, SOLIDS, COMPUTER...
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This short paper is in response to one that appeared in this journal a few years ago [2]. The article was a comment on a previous paper [1], which presented the transformation equations between the standard two-port parameters. The equations were stated to be valid for complex terminations; which are useful when S-parameters are treated. The authors in [2] made some incorrect conclusions concerning the concept of "generalized scattering parameters", and this paper seeks to clarify the...
Topics: NASA Technical Reports Server (NTRS), COMPLEX SYSTEMS, PARAMETER IDENTIFICATION, MATHEMATICAL...
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by NASA Technical Reports Server (NTRS)
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Non-homologous end joining (NHEJ) is the dominant DNA double strand break (DSB) repair pathway and involves several NHEJ proteins such as Ku, DNA-PKcs, XRCC4, Ligase IV and so on. Once DSBs are generated, Ku is first recruited to the DNA end, followed by other NHEJ proteins for DNA end processing and ligation. Because of the direct ligation of break ends without the need for a homologous template, NHEJ turns out to be an error-prone but efficient repair pathway. Some mechanisms have been...
Topics: NASA Technical Reports Server (NTRS), PROTEINS, MATHEMATICAL MODELS, NUMERICAL ANALYSIS,...
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by NASA Technical Reports Server (NTRS)
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Quite often the dynamicist will be faced with having an electric drive motor as a link in the elastic path of a structure such that the motor's characteristics must be taken into account to properly represent the dynamics of the primary structure. He does not want to model it so accurately that he could get detailed stress and displacements in the motor proper, but just sufficiently to represent its inertia loading and elastic behavior from its mounting bolts to its drive coupling. Described...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC MOTORS, MATHEMATICAL MODELS, ROTORS, STATORS, BOLTS,...
Judgements of the loudness of pure-tone sound stimuli yield a loudness function which relates perceived loudness to stimulus amplitude. A loudness function is derived from physical evidence alone without regard to human judgments. The resultant loudness function is L=K(q-q0), where L is loudness, q is effective sound pressure (specifically q0 at the loudness threshold), and K is generally a weak function of the number of stimulated auditory nerve fibers. The predicted function is in agreement...
Topics: NASA Technical Reports Server (NTRS), AUDITORY STIMULI, LOUDNESS, MATHEMATICAL MODELS,...
The SOFIA Aircraft System (AS) Phase 1 Study was a broad-based study which addressed itself to satisfying technical and programmatic requirements by drawing from existing technology and applying cost-efficient commercial approaches to the aircraft modification. In this SOFIA AS Phase 2 Study, five critical areas of the aircraft were selected for more detailed investigation: forward pressure bulkhead, aft bulkhead, 'free' shell to bulkhead interface, shell cut-out to bulkhead interface, and...
Topics: NASA Technical Reports Server (NTRS), BULKHEADS, FINITE ELEMENT METHOD, SOFIA (AIRBORNE...
A mathematical model for the gas chromatograph was developed which incorporates the heretofore neglected transport mechanisms of intraparticle diffusion and rates of adsorption. Because a closed-form analytical solution to the model does not appear realizable, techniques for the numerical solution of the model equations are being investigated. Criteria were developed for using a finite terminal boundary condition in place of an infinite boundary condition used in analytical solution techniques....
Topics: NASA Technical Reports Server (NTRS), GAS CHROMATOGRAPHY, MATHEMATICAL MODELS, ADSORPTION, ANALYTIC...
An empirical model of the global atomic oxygen and helium distributions in the thermosphere is developed in a magnetic coordinate system and compared to similar models which are expanded in geographic coordinates. The advantage of using magnetic coordinates is that fewer terms are needed to make predictions which are nearly identical to those which would be obtained from a geographic model with longitudinal and universal time corrections. Magnetic coordinates are more directly related to the...
Topics: NASA Technical Reports Server (NTRS), DENSITY DISTRIBUTION, GEOMAGNETISM, MAGNETIC EQUATOR, OXYGEN,...
A description of the techniques and methodology for making outdoor I-V measurements of solar cells is given. Temperature and irradiance measurement, experimental arrangement, data acquisition system and I-V data transformations are discussed. Data are presented comparing outdoor measurements to indoor measurements using a pulsed solar simulator.
Topics: NASA Technical Reports Server (NTRS), IRRADIANCE, PHOTOVOLTAIC CELLS, SOLAR CELLS, TEMPERATURE,...
The origin of the short period comets (SPC) (periods less than 200 years), the dynamical formation of their present reservoir(s), the cause and rate of their transport to the inner planetary region where they can be detected, and the magnitude of selection effects in their discovery are important research questions directly coupled to the goals of understanding the origin and evolution of the Solar System. To address these questions in an intensive way, an interdisciplinary, five month long...
Topics: NASA Technical Reports Server (NTRS), COMETS, SOLAR SYSTEM EVOLUTION, MATHEMATICAL MODELS, ORBITS,...
The problem of determining the cost impact attributable to perturbations in an aerospace R and D program schedule is discussed in terms of the diminishing availability of funds. The methodology from which a model is presented for updating R and D cost estimates as a function of perturbations in program time is presented.
Topics: NASA Technical Reports Server (NTRS), AEROSPACE INDUSTRY, COST ESTIMATES, SCHEDULING, GRAPHS...
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by NASA Technical Reports Server (NTRS)
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Effectively communicate qualitative and quantitative information orally and in writing. Explain the application of fundamental physical principles to various physical phenomena. Apply appropriate problem-solving techniques to practical and meaningful problems using graphical, mathematical, and written modeling tools. Work effectively in collaborative groups.
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, PHYSICAL FACTORS, PROBLEM SOLVING,...
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Causal solutions for effective relative complex permittivities of plasmas are derived. Both lossless and lossy plasmas are considered.
Topics: NASA Technical Reports Server (NTRS), CAUSES, MATHEMATICAL MODELS, PERMITTIVITY, PLASMAS (PHYSICS),...
Configurations of MLS Flare Elevation Systems that can be considered reasonable and practical in actual implementation are identified. Each of these are analyzed and compared with respect to (1) computational requirement, (2) required coverage, and (3) accuracy including altitude and sink-rate estimation error performance.
Topics: NASA Technical Reports Server (NTRS), GLIDE PATHS, MICROWAVE LANDING SYSTEMS, ALGORITHMS, AZIMUTH,...
Equations are developed which give the pressure profile, the forces and torques on a disk pendulum by means of point source wave theory from acoustics. The pressure, force and torque equations for an unbaffled disk are developed. These equations are then used to calculate the apparent mass and apparent inertia for the pendulum.
Topics: NASA Technical Reports Server (NTRS), ACOUSTICS, PENDULUMS, PRESSURE DISTRIBUTION, TORQUE, DISKS...
The goal of this task is to analyze the performance of single and multiple FTP transfer between SCF's and the Goddard DAAC. We developed an analytic model to compute the performance of FTP sessions as a function of various key parameters, implemented the model as a program called FTP Analyzer, and carried out validations with real data obtained by running single and multiple FTP transfer between GSFC and the Miami SCF. The input parameters to the model include the mix to FTP sessions...
Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, IMAGING SPECTROMETERS, PERFORMANCE...
This paper presents a practical application of response surface methods (RSM) to correlate a finite element model of a structural modal test. The test article is a quasi-cylindrical inflatable structure which primarily consists of a fabric weave, with an internal bladder and metallic bulkheads on either end. To mitigate model size, the fabric weave was simplified by representing it with shell elements. The task at hand is to represent the material behavior of the weave. The success of the model...
Topics: NASA Technical Reports Server (NTRS), FINITE ELEMENT METHOD, MATHEMATICAL MODELS, WOVEN COMPOSITES,...
The question of whether the micro scale controls the macro scale or vice-versa remains one of the most challenging problems in plasmas. A particular topic of interest within this context is collisionless magnetic reconnection, where both points of views are espoused by different groups of researchers. This presentation will focus on this topic. We will begin by analyzing the global properties of magnetic reconnection. Following that, we discuss properties of electron diffusion region dynamics...
Topics: NASA Technical Reports Server (NTRS), ELECTRON DIFFUSION, TEMPORAL DISTRIBUTION, SECULAR...
In this research an efficient parallel algorithm for 3-D directionally split problems is developed. The proposed algorithm is based on a reformulated version of the pipelined Thomas algorithm that starts the backward step computations immediately after the completion of the forward step computations for the first portion of lines This algorithm has data available for other computational tasks while processors are idle from the Thomas algorithm. The proposed 3-D directionally split solver is...
Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, MATRICES (MATHEMATICS), PARALLEL COMPUTERS,...
Previous intercity travel demand models in terms of their ability to predict air travel in a useful way and the need for disaggregation in the approach to demand modelling are evaluated. The viability of incorporating non-conventional factors (i.e. non-econometric, such as time and cost) in travel demand forecasting models are determined. The investigation of existing models is carried out in order to provide insight into their strong points and shortcomings. The model is characterized as a...
Topics: NASA Technical Reports Server (NTRS), AIR TRANSPORTATION, DEMAND (ECONOMICS), MATHEMATICAL MODELS,...
A comprehensive mathematical model by which the collective behavior of a very large number of atoms within a metal or alloy can accurately be simulated was developed. Work was done in order to predict and modify the strength of materials to suit our technological needs. The method developed is useful in studying atomic interactions related to dislocation motion and crack extension.
Topics: NASA Technical Reports Server (NTRS), ATOMIC STRUCTURE, COMPUTERIZED SIMULATION, FRACTURE STRENGTH,...