15
15

Jul 5, 2017
07/17

by
Maximum Entropy Formalism Conference, Massachusetts Institute of Technology, 1978; Levine, Raphael D; Tribus, Myron; Massachusetts Institute of Technology

texts

######
eye 15

######
favorite 1

######
comment 0

Includes bibliographical references

Topics: Maximum entropy method, Entropie (Théorie de l'information), Entropie (Théorie de...

This paper concerns decisions under uncertainty in which the probabilities of the states of nature are only approximately known. Decision problems involving three states of nature are studied. This is due to the fact that some key issues do not arise in two-state problems, while probability spaces with more than three states of nature are essentially impossible to graph. The primary focus is on two levels of probabilistic information. In one level, the three probabilities are separately rounded...

Topics: NASA Technical Reports Server (NTRS), DECISION MAKING, PROBABILITY THEORY, STATISTICAL DECISION...

A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather...

Topics: NASA Technical Reports Server (NTRS), MAXIMUM ENTROPY METHOD, PROBABILITY THEORY, ESTIMATING,...

The first task for image restoration using the Maximum Entropy Method (MEM) in IRAF, called IRMEO, is described. The underlining algorithm is the approximate Newton method for optimization. The basic input images and parameters for deconvolution are described in some detail. Results of preliminary tests, including the number of iterations, required CPU time on a variety of computers, and deconvolved images are reported and compared with those from other deconvolution methods. The merits and...

Topics: NASA Technical Reports Server (NTRS), IMAGE PROCESSING, IMAGE RECONSTRUCTION, MAXIMUM ENTROPY...

222
222

May 22, 2011
05/11

by
Nanua, Prabjo

texts

######
eye 222

######
favorite 0

######
comment 0

Two control schemes are compared for parallel robotic mechanisms actuated by hydraulic cylinders. One scheme, the 'rate based scheme', uses the position and rate information only for feedback. The second scheme, the 'force based scheme' feeds back the force information also. The force control scheme is shown to improve the response over the rate control one. It is a simple constant gain control scheme better suited to parallel mechanisms. The force control scheme can be easily modified for the...

Topics: CONTROL SYSTEMS DESIGN, KALMAN-SCHMIDT FILTERING, MAN MACHINE SYSTEMS, ROBOT CONTROL, ROBOT...

327
327

Sep 20, 2010
09/10

by
Uphoff, Chaunce

texts

######
eye 327

######
favorite 0

######
comment 0

This paper is a presentation of some practical aspects of orbital transfer from Geosynchronous Transfer Orbit (GTO) to close, near-circular orbits of the Moon. The intent is to identify the important parameters affecting the problem and to bound (approximately) the range of required delta V for a spacecraft that has been placed in GTO. The basic geometric relationships are described and the dynamics are simulated by use of the Zero-Sphere-of Influence Patched Conic method. It is found that the...

Topics: ANALYSIS (MATHEMATICS), EXPONENTIAL FUNCTIONS, MATHEMATICAL MODELS, PETRI NETS, MARKOV CHAINS,...

135
135

May 22, 2011
05/11

by
Rogers, Erika; Murphy, Robin R

texts

######
eye 135

######
favorite 0

######
comment 0

This paper describes a new approach in semi-autonomous mobile robots. In this approach the robot has sufficient computerized intelligence to function autonomously under a certain set of conditions, while the local system is a cooperative decision making unit that combines human and machine intelligence. Communication is then allowed to take place in a common mode and in a common language. A number of exception-handling scenarios that were constructed as a result of experiments with actual...

Topics: ANGULAR RESOLUTION, LUMINOSITY, MAGNITUDE, MASSIVE STARS, MOLECULAR GASES, MOLECULES, CONTINUUMS,...

The correlation and spectral analysis methods for uniformly sampled stationary random signals, estimation of their spectral moments, and problems arising due to nonstationary are reviewed. Some of these methods are already in routine use in atmospheric radar experiments. Other methods based on the maximum entropy principle and time series models have been used in analyzing data, but are just beginning to receive attention in the analysis of radar signals. These methods are also briefly...

Topics: NASA Technical Reports Server (NTRS), CORRELATION, DOPPLER RADAR, MAXIMUM ENTROPY METHOD,...

This final report for the project discusses the attempts to model, using different methods, microwave image reconstruction. Maximum Entropy Method was not successful. Attempts to use Singular Value Decomposition (SVD) got some good results after initial failure. SVD is based upon a theory of linear algebra, to the effect that any M X N Matrix A whose number of rows M is greater than or equal to its number of columns, N can be written as the product of an M X N column-orthogonal matrix U, an N X...

Topics: NASA Technical Reports Server (NTRS), CONJUGATE GRADIENT METHOD, CURRENT DISTRIBUTION, IMAGE...

We describe a process of pyramid maximum entropy reconstruction of images from the IRAS survey data.

Topics: NASA Technical Reports Server (NTRS), IMAGE RECONSTRUCTION, IMAGE RESOLUTION, INFRARED ASTRONOMY...

For the same expert knowledge, if one uses different &- and V-operations in a fuzzy control methodology, one ends up with different control strategies. Each choice of these operations restricts the set of possible control strategies. Since a wrong choice can lead to a low quality control, it is reasonable to try to loose as few possibilities as possible. This idea is formalized and it is shown that it leads to the choice of min(a + b,1) for V and min(a,b) for &. This choice was tried on...

Topics: NASA Technical Reports Server (NTRS), CONTROL THEORY, FUZZY SYSTEMS, MAXIMUM ENTROPY METHOD,...

Algorithms to estimate the power spectrum using Maximum Entropy Methods were developed. These algorithms were coded in FORTRAN 77 and were implemented on the VAX 780. The important considerations in this analysis are: (1) resolution, i.e., how close in frequency two spectral components can be spaced and still be identified; (2) dynamic range, i.e., how small a spectral peak can be, relative to the largest, and still be observed in the spectra; and (3) variance, i.e., how accurate the estimate...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, ESTIMATING, MAXIMUM ENTROPY METHOD, POWER...

There are a variety of algorithms for deconvolution of blurred images, each having its own criteria or statistic to be optimized in order to estimate the original image data. Using the Interactive Data Language (IDL), we have implemented the Maximum Likelihood, Maximum Entropy, Maximum Residual Likelihood, and sigma-CLEAN algorithms in a unified environment called DeConv_Tool. Most of the algorithms have as their goal the optimization of statistics such as standard deviation and mean of...

Topics: NASA Technical Reports Server (NTRS), APPLICATIONS PROGRAMS (COMPUTERS), AUTOCORRELATION, ENTROPY,...

The procedure of microwave imaging by maximum entropy method is discussed. First, the relationship between the induced current on the metal object surface and the scattered field is introduced. Our imaging concept is to reconstruct the induced current on the object surface from the measured scattered field. The object configuration will be provided by the induced current which is zero everywhere except on the object surface. Future work is also included with focus on the application of...

Topics: NASA Technical Reports Server (NTRS), IMAGING TECHNIQUES, METAL SURFACES, MICROWAVE IMAGERY,...

The maximum entropy technique was successfully applied to the deconvolution of overlapped chromatographic peaks. An algorithm was written in which the chromatogram was represented as a vector of sample concentrations multiplied by a peak shape matrix. Simulation results demonstrated that there is a trade off between the detector noise and peak resolution in the sense that an increase of the noise level reduced the peak separation that could be recovered by the maximum entropy method. Real data...

Topics: NASA Technical Reports Server (NTRS), TIME DEPENDENCE, CHROMATOGRAPHY, MULTIPLEXING, NOISE...

92
92

Jul 13, 2016
07/16

by
Steve F. Russell, Iowa State University

texts

######
eye 92

######
favorite 0

######
comment 0

The practical aspects of spectral analysis are contrasted with the mathematical theory. Treatment is limited to ergodic processes and emphasizes data window and noise effects. The Discrete Fourier Transform (DFT) and Maximum Entropy Method (MEM) are covered extensively both in theory and application with FORTRAN programs and many examples being provided. Several of the chapters are tutorial and discuss the important topics of sampling theory and system analysis. Topics on MEM include a complete...

Topics: finite time series analysis, Fourier transforms, convolution, autoregression, Hilbert space and...

256
256

Jul 23, 2010
07/10

by
Lin, Chin-Shu

texts

######
eye 256

######
favorite 0

######
comment 0

For hypersonic flow with a shock wave, there is a similar solution consistent throughout the viscous and inviscid layers along a very slender three-fourths-power body of revolution The strong pressure interaction problem can then be treated by the method of similarity. Numerical calculations are performed in the viscous region with the edge pressure distribution known from the inviscid similar solutions. The compressible laminar boundary-layer equations are transformed into a system of ordinary...

Topics: APPLICATIONS PROGRAMS (COMPUTERS), MATRICES (MATHEMATICS), NONLINEARITY, LARGE SPACE STRUCTURES,...

The autoregressive (AR) model of a random process is interpreted in the light of the Prony's relation which relates a complex conjugate pair of poles of the AR process in the z-plane (or the z domain) on the one hand, to the complex frequency of one complex harmonic function in the time domain on the other. Thus the AR model of a time series is one that models the time series as a linear combination of complex harmonic functions, which include pure sinusoids and real exponentials as special...

Topics: NASA Technical Reports Server (NTRS), AUTOREGRESSIVE PROCESSES, MAXIMUM ENTROPY METHOD, TIME SERIES...

A method is developed for prediction of ozone levels in planetary atmospheres. This method is formulated in terms of error covariance matrices, and is associated with both direct measurements, a priori first guess profiles, and a weighting function matrix. This is described by the following linearized equation: y = A(matrix) x X + eta, where A is the weighting matrix and eta is noise. The problems to this approach are: (1) the A matrix is near singularity; (2) the number of unknowns in the...

Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC COMPOSITION, MAXIMUM ENTROPY METHOD, OZONE,...

The goal of any modeling methodology is to develop a mathematical description of a system that is accurate in its representation and also permits analysis of structural and/or performance properties. Inherently, trade-offs exist between the level detail in the model and the ease with which analysis can be performed. Petri nets (PN's), a highly graphical modeling methodology for Discrete Event Dynamic Systems, permit representation of shared resources, finite capacities, conflict,...

Topics: NASA Technical Reports Server (NTRS), ANALYSIS (MATHEMATICS), EXPONENTIAL FUNCTIONS, MATHEMATICAL...

Topics include: (1) polar coordinate transformations (M83); (2) multispectral ratios (M82); (3) maximum entropy restoration (M87); (4) automated computation of stellar magnitudes in nebulosity; (5) color and polarization; (6) aliasing.

Topics: NASA Technical Reports Server (NTRS), ASTRONOMY, IMAGE PROCESSING, MAXIMUM ENTROPY METHOD, POLAR...

An investigation to develop, implement, and evaluate signal analysis techniques for the detection and classification of incipient mechanical failures in turbomachinery is reviewed. A brief description of the Space Shuttle Main Engine (SSME) test/measurement program is presented. Signal analysis techniques available to describe dynamic measurement characteristics are reviewed. Time domain and spectral methods are described, and statistical classification in terms of moments is discussed. Several...

Topics: NASA Technical Reports Server (NTRS), ENGINE MONITORING INSTRUMENTS, FUEL PUMPS, SIGNAL ANALYSIS,...

Time spectra of the critical frequency f sub o E sub s and blanketing frequency f sub b E sub s for the records of a spaced chain of ionosphere vertical sounding stations were studied by means of a maximum entropy method, while coherence spectra were analyzed with the Blackman and Tukey method. It was found out that the frequency parameters spectrum of E sub s within the range of 1-10 cycles/h are discrete with one or two maxima. The first, a low frequency maximum with T=40 min, is of larger...

Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC SOUNDING, ATMOSPHERIC TURBULENCE, E REGION,...

Large scale waves in the ionosphere, gravity waves in the thermosphere, and large scale waves in the thermosphere observed by AE satellites are discharged.

Topics: NASA Technical Reports Server (NTRS), EARTH IONOSPHERE, GRAVITY WAVES, SATELLITE OBSERVATION,...

The IRAS survey data can be used successfully to produce images of extended objects. The major difficulty, viz. non-uniform sampling, different response functions for each detector, and varying signal-to-noise levels for each detector for each scan, were resolved. The results of three different image construction techniques are compared: co-addition, constrained least squares, and maximum entropy. The maximum entropy result is superior. An image of the galaxy M51 with an average spatial...

Topics: NASA Technical Reports Server (NTRS), DATA PROCESSING, GALAXIES, IMAGING TECHNIQUES, LEAST SQUARES...

We have made deconvolved maps of M101 in each of the 4 IRAS bands using a new maximum-entropy based model for reconstructing distributions with correlated structure on multiple scales. This new deconvolution procedure, developed by Weir (1992, J.Opt.Soc.Am., submitted), is superior to other maximum entropy-based techniques for several reasons. For our purposes, an important advantage is that it has less artifacts and greatly reduced systematic biases compared with the 'HiRes' maps of M101...

Topics: NASA Technical Reports Server (NTRS), COLD GAS, FAR INFRARED RADIATION, H II REGIONS, INFRARED...

The IRAS survey data can be used successfully to produce images of extended objects. The major difficulties, viz. non-uniform sampling, different response functions for each detector, and varying signal-to-noise levels for each detector for each scan, were resolved. The results of three different image construction techniques are compared: co-addition, constrained least squares, and maximum entropy. The maximum entropy result is superior. An image of the galaxy M51 with an average spatial...

Topics: NASA Technical Reports Server (NTRS), COMPUTERIZED SIMULATION, GALAXIES, IMAGE RECONSTRUCTION,...

A geometric approach, similar to Van Leer's MUSCL schemes, is used to construct a second-order accurate generalization of Godunov's method for solving scalar conservation laws. By making suitable approximations, a scheme is obtained which is easy to implement and total variation diminishing. The entropy condition is also investigated from the standpoint of the spreading of rarefaction waves. Quantitative information is obtained for Godunov's method on the rate of spreading which explain the...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, APPROXIMATION, CONSERVATION LAWS, DIFFERENTIAL...

215
215

May 27, 2011
05/11

by
Seiff, Alvin; Lester, Pete

texts

######
eye 215

######
favorite 0

######
comment 0

A major objective of the grant was to complete the fabrication, test, and evaluation of the atmosphere structure experiment on the Galileo Probe, and to receive, analyze, and interpret data received from the spacecraft. The grantee was competitively selected to be Principal Investigator of Jupiter's atmosphere structure on the Galileo Probe. His primary motivation was to learn as much as possible about Jupiter's atmosphere by means of a successful atmosphere structure experiment, and to support...

Topics: SOLAR FLARES, SIMULATION, COMPUTER PROGRAMS, X RAY SPECTROSCOPY, SOLAR OBSERVATORIES, MAXIMUM...

Continuous probability density functions and discrete probability mass functions are tabulated which maximize the differential entropy or absolute entropy, respectively, among all probability distributions with a given L sub p norm (i.e., a given pth absolute moment when p is a finite integer) and unconstrained or constrained value set. Expressions for the maximum entropy are evaluated as functions of the L sub p norm. The most interesting results are obtained and plotted for unconstrained...

Topics: NASA Technical Reports Server (NTRS), DATA COMPRESSION, MAXIMUM ENTROPY METHOD, PROBABILITY DENSITY...

A time-series technique is presented for identifying the dynamic characteristics of the human operator in manual control tasks from relatively short records of experimental data. Control of system excitation signals used in the identification is not required. The approach is a multi-channel identification technique for modeling multi-input/multi-output situations. The method presented includes statistical tests for validity, is designed for digital computation, and yields estimates for the...

Topics: NASA Technical Reports Server (NTRS), HUMAN FACTORS ENGINEERING, HUMAN PERFORMANCE, MAN MACHINE...

In the Control Systems Division of the Systems Dynamics Laboratory of the NASA/MSFC, a Ground Facility (GF), in which the dynamics and control system concepts being considered for Large Space Structures (LSS) applications can be verified, was designed and built. One of the important aspects of the GF is to design an analytical model which will be as close to experimental data as possible so that a feasible control law can be generated. Using Hyland's Maximum Entropy/Optimal Projection Approach,...

Topics: NASA Technical Reports Server (NTRS), CONTROL SYSTEMS DESIGN, LARGE SPACE STRUCTURES, MAXIMUM...

Far-infrared continuum studies from the Kuiper Airborne Observatory are described that are designed to fully exploit the small-scale spatial information that this facility can provide. This work gives the clearest picture to data on the structure of galactic and extragalactic star forming regions in the far infrared. Work is presently being done with slit scans taken simultaneously at 50 and 100 microns, yielding one-dimensional data. Scans of sources in different directions have been used to...

Topics: NASA Technical Reports Server (NTRS), IMAGE PROCESSING, INFRARED ASTRONOMY, INTERSTELLAR MATTER,...

There is a necessity of having an automatic procedure for reliable estimation of the quality of the measurement of particle size from QELS (Quasi-Elastic Light Scattering). Getting the measurement itself, before any error estimates can be made, is a problem because it is obtained by a very indirect measurement of a signal derived from the motion of particles in the system and requires the solution of an inverse problem. The eigenvalue structure of the transform that generates the signal is such...

Topics: NASA Technical Reports Server (NTRS), COVARIANCE, ERROR ANALYSIS, LIGHT SCATTERING, MATRICES...

The National Geophysical Data Center archives data of the solar-terrestrial environment. The USAF Radio Solar Telescope Network (RSTN) data allow performance of time series analysis to determine temporal oscillations as low as three seconds. The X13/3B flare which erupted in region 4474 (S12E43) on the 24 to 25 of April 1984, was selected. The soft X-rays, 1 to 8 A, remained above X-levels for 50 minutes and the radio emissions measured at Learmonth Solar Observatory reached a maximum of 3.15 x...

Topics: NASA Technical Reports Server (NTRS), OSCILLATIONS, SOLAR RADIO EMISSION, STATISTICAL ANALYSIS,...

The underlying philosophy and motivation of the optimal projection/maximum entropy (OP/ME) stochastic modeling and reduced control design methodology for high order systems with parameter uncertainties are discussed. The OP/ME design equations for reduced-order dynamic compensation including the effect of parameter uncertainties are reviewed. The application of the methodology to several Large Space Structures (LSS) problems of representative complexity is illustrated.

Topics: NASA Technical Reports Server (NTRS), CONTROL SYSTEMS DESIGN, DYNAMIC STRUCTURAL ANALYSIS, LARGE...

A relevance measure based on Jaynes maximum entropy principle is introduced. Information quality is the conjunction of accuracy and relevance. The formalism based on information quality is developed for one-agent applications. The robot requires a well defined working environment where properties of each object must be accurately specified.

Topics: NASA Technical Reports Server (NTRS), CONTROL SYSTEMS DESIGN, KALMAN-SCHMIDT FILTERING, MAN MACHINE...

We present results of simulations of the distribution of 1809 keV radiation from the decay of Al-26 in the Galaxy. Recent observations of this emission line using the Gamma Ray Imaging Spectrometer (GRIS) have indicated that the bulk of the AL-26 must have a velocity of approx. 500 km/ s. We have previously shown that a velocity this large could be maintained over the 10(exp 6) year lifetime of the Al-26 if it is trapped in dust grains that are reaccelerated periodically in the ISM. Here we...

Topics: NASA Technical Reports Server (NTRS), SPATIAL DISTRIBUTION, ALUMINUM ISOTOPES, GALAXIES, DATA...

A stochastic control model of the NASA/MSFC Ground Facility for Large Space Structures (LSS) control verification through Maximum Entropy (ME) principle adopted in Hyland's method was presented. Using ORACLS, a computer program was implemented for this purpose. Four models were then tested and the results presented.

Topics: NASA Technical Reports Server (NTRS), APPLICATIONS PROGRAMS (COMPUTERS), LARGE SPACE STRUCTURES,...

Information Theory Inference, better known as the Maximum Entropy Method, was used to infer the lateral density distribution inside the Earth. The approach assumed that the Earth consists of indistinguishable Maxwell-Boltzmann particles populating infinitesimal volume elements, and followed the standard methods of statistical mechanics (maximizing the entropy function). The GEM 10B spherical harmonic gravity field coefficients, complete to degree and order 36, were used as constraints on the...

Topics: NASA Technical Reports Server (NTRS), DENSITY DISTRIBUTION, EARTH CORE, EARTH CRUST, EARTH...

This paper deals with the accurate microscopic simulation and macroscopic modeling of extreme non-equilibrium phenomena, such as encountered during hypersonic entry into a planetary atmosphere. The state-to-state microscopic equations involving internal excitation, de-excitation, dissociation, and recombination of nitrogen molecules due to collisions with nitrogen atoms are solved time-accurately. Strategies to increase the numerical efficiency are discussed. The problem is then modeled using a...

Topics: NASA Technical Reports Server (NTRS), SIMULATION, MACROSCOPIC EQUATIONS, MATHEMATICAL MODELS,...

309
309

Jun 1, 2011
06/11

by
Tannehill, J. C

texts

######
eye 309

######
favorite 0

######
comment 0

This report consists of two published papers, 'Computation of Magnetohydrodynamic Flows Using an Iterative PNS Algorithm' and 'Numerical Simulation of Turbulent MHD Flows Using an Iterative PNS Algorithm'.

Topics: MICROWAVE ANISOTROPY PROBE, BACKGROUND RADIATION, ENERGY DISSIPATION, MAXIMUM ENTROPY METHOD,...

We consider the problem of image reconstruction from a finite number of projections over the space L(sup 1)(Omega), where Omega is a compact subset of the set of Real numbers (exp 2). We prove that, given a discretization of the projection space, the function that generates the correct projection data and maximizes the Boltzmann-Shannon entropy is piecewise constant on a certain discretization of Omega, which we call the 'optimal grid'. It is on this grid that one obtains the maximum resolution...

Topics: NASA Technical Reports Server (NTRS), COMPUTER AIDED TOMOGRAPHY, IMAGE RECONSTRUCTION, MAXIMUM...

One of the major activities of any experimentalist is data analysis and reduction. In solar physics, remote observations are made of the sun in a variety of wavelengths and circumstances. In no case is the data collected free from the influence of the design and operation of the data gathering instrument as well as the ever present problem of noise. The presence of significant noise invalidates the simple inversion procedure regardless of the range of known correlation functions. The Maximum...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, IMAGE PROCESSING, IMAGE RECONSTRUCTION, MAXIMUM...

Background material and a systems analysis of a multifrequency aperture - synthesizing microwave radiometer system is presented. It was found that the system does not exhibit high performance because much of the available thermal power is not used in the construction of the image and because the image that can be formed has a resolution of only ten lines. An analysis of image reconstruction is given. The system is compared with conventional aperture synthesis systems.

Topics: NASA Technical Reports Server (NTRS), APERTURES, MAPPING, MICROWAVE RADIOMETERS, COMPARISON,...

A number of topics supporting the systems analysis of a multifrequency aperture-synthesizing microwave radiometer system are discussed. Fellgett's (multiple) advantage, interferometer mapping behavior, mapping geometry, image processing programs, and sampling errors are among the topics discussed. A FORTRAN program code is given.

Topics: NASA Technical Reports Server (NTRS), APERTURES, MAPPING, MICROWAVE RADIOMETERS, COMPUTER PROGRAMS,...

The Invasive Species Forecasting System (ISFS) is an online decision support system that allows users to load point occurrence field sample data for a plant species of interest and quickly generate habitat suitability maps for geographic regions of interest, such as a national park, monument, forest, or refuge. Target customers for ISFS are natural resource managers and decision makers who have a need for scientifically valid, model- based predictions of the habitat suitability of plant species...

Topics: NASA Technical Reports Server (NTRS), CHESAPEAKE BAY (US), HABITATS, ON-LINE SYSTEMS, ECOLOGY,...

A validated technology data base is being developed in the areas of control/structures interaction, deployment dynamics, and system performance for Large Space Structures (LSS). A Ground Facility (GF), in which the dynamics and control systems being considered for LSS applications can be verified, was designed and built. One of the important aspects of the GF is to verify the analytical model for the control system design. The procedure is to describe the control system mathematically as well...

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, CONTROL SYSTEMS DESIGN, MATHEMATICAL...

We have developed a new Bayesian image reconstruction method that has been shown to be superior to the best implementations of other competing methods, including Goodness-of-Fit methods such as Least-Squares fitting and Lucy-Richardson reconstruction, as well as Maximum Entropy (ME) methods such as those embodied in the MEMSYS algorithms. Our new method is based on the concept of the pixon, the fundamental, indivisible unit of picture information. Use of the pixon concept provides an improved...

Topics: NASA Technical Reports Server (NTRS), BAYES THEOREM, GALAXIES, IMAGE RECONSTRUCTION, IMAGE...

With increased demand for high resolution ultrasonic evaluation, computer based systems or work stations become essential. The ultrasonic spectroscopy method of nondestructive evaluation (NDE) was used to develop a high resolution ultrasonic inspection system supported by modern signal processing, pattern recognition, and neural network technologies. The basic system which was completed consists of a 386/20 MHz PC (IBM AT compatible), a pulser/receiver, a digital oscilloscope with serial and...

Topics: NASA Technical Reports Server (NTRS), APPLICATIONS PROGRAMS (COMPUTERS), COMPUTER PROGRAMMING,...