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,...

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,...

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...

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...

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,...

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,...

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,...

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...

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,...

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.

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,...

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,...

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,...

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,...

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...

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 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...

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,...

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,...

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...

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,...

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...

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...

For abstract, see N72-17902.

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, MANUALS, SPACECRAFT...

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...

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...

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,...

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,...

Topics: NASA Technical Reports Server (NTRS), RESEARCH PROJECTS, URBAN PLANNING, URBAN TRANSPORTATION,...

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,...

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,...

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,...

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...

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,...

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...

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,...

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,...

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, RELIABILITY, MATHEMATICAL...

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,...

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...

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,...

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...

For abstract, see N72-17902.

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, ERROR ANALYSIS, MANUALS, SPACECRAFT...