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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.-H. Yu S.K. Mitra Department of Electrical and Computer Engineering Signal and Image Processing Laboratory University of California Santa Barbara CA USA

A new direct contrast enhancement algorithm is proposed. It can be used to enhance the contrast of an image without increasing the dynamic range of the pixel values. A distinctive property of the proposed method is that it yields results matching the characteristic of the human visual system. The histogram of the enhanced image has almost the same shape as that of the original image.< >

关键词： Image enhancement Dynamic range Pixel Histograms Shape Humans Visual system Displays Computational complexity Signal processing

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Nonlinear filters for image sharpening and smoothing

Nonlinear filters for image sharpening and smoothing

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IEEE International Conference on Systems engineering

作者： Mitra Yu Signal and Image Processing Laboratory Department of Electrical & Computer Engineering University of California Santa Barbara CA USA

A general approach to the transform-magnitude-shaping-based image enhancement method is advanced. In the method, the magnitude of the input image transform is modified using a nonlinear mapping expressible as a power series, while its phase is kept invariant. The inverse transform of the modified image transform results in a sharpening or smoothing depending on the choice of the power series coefficients. Further improvement in the overall enhancement is achieved by a two-channel processing scheme which is implemented by applying different transform amplitude shaping methods to the low-frequency and high-frequency components. Examples the proposed enhancement method are included.< >

关键词： Filtering Image processing Transforms

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A New Method for Evaluating Floquet Characteristic Exponents of Periodic Linear Systems

A New Method for Evaluating Floquet Characteristic Exponents...

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American Control Conference (ACC)

作者： J. Zhu S. K. Vemula Electrical and Computer Engineering Department Remote Sensing and Image Processing Laboratory Louisiana State University Baton Rouge LA USA Electrical and Computer Engineering Department Louisiana State University Baton Rouge LA USA

It is well-known that the stability of linear periodic (LP) systems can be assessed using Floquet Characteristic Exponents (FCE). In this paper, a new method is presented for evaluating FCE for nth-order scalar periodic linear systems based on a recently developed unified eigenvalue theory for linear time-varying (LTV) Systems [1]. The new theory allows FCEs to be evaluated from the DC term of the Fourier series of periodic PD-eigen-values of a LP system. Comparing to the well-known Monodromy Matrix (MM) method and Infinite Dimensional Determinant (IDD) method for evaluating FCE 1 the solutions obtained by the new method have rapid local convergence. This new method also allow stability boundaries in the parameter space of a LP system to be evaluated and plotted directly. The new results shed some light OL the general stability assessment problem for vector periodic linear systems and aperiodic LTV systems. Further studies along this direction are also discussed in this paper.

关键词： Linear systems Eigenvalues and eigenfunctions Vectors Fourier series Frequency Equations Stability analysis Remote sensing Image processing Laboratories

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Scanning tunneling microscope study of GaAs(001) surfaces grown by migration enhanced epitaxy

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1993年第4期11卷 1370-1373页

作者： J. Kim M. C. Gallagher R. F. Willis Jianming Fu D. L. Miller The Department of Physics The Pennsylvania State University University Park Pennsylvania 16802 Electronic Materials and Processing Research Laboratory Department of Electrical and Computer Engineering The Pennsylvania State University University Park Pennsylvania 16802

We report an investigation of the morphology of p‐type GaAs(001) surfaces using scanning tunneling microscopy (STM). The substrates were prepared using two methods: migration enhanced epitaxy (MEE) and standard molecular‐beam epitaxy (MBE). The STM measurements were performed ex situ using As decapping. Analysis indicates that the overall step density of the MEE samples decreases as the growth temperature is increased. Nominally flat samples grown at 300 °C exhibited step densities of 10.5 steps/1000 Å along [110] dropping to 2.5 steps at 580 °C. MEE samples exhibited a lower step density than MBE samples. However as‐grown surfaces exhibited a larger distribution of step heights. Annealing the samples reduced the step height distribution exposing fewer atomic layers. Samples grown by MEE at 580 °C and annealed for 2 min displayed the lowest step density and the narrowest step height distribution. All samples displayed an anisotropic step density. We found a ratio of A‐type to B‐type steps of between 2 and 3 which directly reflects the difference in the incorporation energy at steps. The aspect ratio increased slightly with growth temperature. We found a similar aspect ratio on samples grown by MBE. This indicates that anisotropic growth during MEE, like MBE, is dominated by incorporation kinetics. MEE samples grown at 580 °C and capped immediately following growth exhibited a number of ‘‘holes’’ in the surface. The holes could be eliminated by annealing the surface prior to quenching.

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Local estimation of Gaussian-based edge enhancement filters using Fourier analysis

Local estimation of Gaussian-based edge enhancement filters ...

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1993 IEEE International Conference on Acoustics, Speech, and Signal processing

作者： B. Wang D.M. Rose A.A. Farag E.J. Delp Engineering Mathematics & Computer Science Department Speed Scientific School University of Louisville Louisville KY USA Computer Vision & Image Processing Laboratory School of Electrical Engineering Purdue University West Lafayette IN USA

An empirical measure for the selection of the edge-enhancement Gaussian filter is developed. The Gaussian filter is specified by its standard deviation sigma ; the filter's spatial support is a function of sigma . An estimation procedure for sigma using Fourier analysis is described. The measure is easy to implement and is based totally on the image at hand. Experimental results suggest that this measure can be used as an aid in deciding the Gaussian filter's spatial support, which is needed to enhance the edges. Other equivalent bandwidth definitions can be used to obtain a measure of the frequency spread in the smoothed image (e.g., the mean-square bandwidth).< >

关键词： Gaussian processes Low pass filters Shape Filtering Frequency Mathematics computer science computer vision Image processing Image segmentation

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Helicopter gearbox fault detection and diagnosis using analog neural networks

Helicopter gearbox fault detection and diagnosis using analo...

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Asilomar Conference on Signals, Systems & computers

作者： P.T. Monsen E.S. Manolakos M. Dzwonczyk Atlantic Aerospace Electronics Corporation Waltham MA USA Communications and Digital Signal Processing Center Electrical And Computer Engineering Department Northeastern University Boston MA USA Information Systems Laboratory Department of Electrical Engineering University of Stanford USA

This paper summarizes the results of two neural hardware implementations of a helicopter gearbox health monitoring system (HMS). Our first hybrid approach and implementation to fault diagnosis is outlined, and our results are summarized using three levels of fault characterization: fault detection (fault or no fault), classification (gear or bearing fault), and identification (fault sub-classes). Our second all-analog implementation exploits the ability, of analog neural hardware to compute the discrete Fourier transform (DFT) as a pre-processor to a neural classifier. Our hardware results compare well with previously published software simulations.< >

关键词： Helicopters Fault detection Fault diagnosis Hardware Discrete Fourier transforms Monitoring Gears Analog computers Computational modeling

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Metal–oxide–semiconductor characterization of silicon surfaces thermally oxidized after reactive ion etching and magnetically enhanced reactive ion etching

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1993年第2期11卷 249-252页

作者： Kenneth T. Settlemyer, Jr. Jerzy Ruzyllo David K. Hwang Herbert J. Leary, Jr. Electronic Materials and Processing Research Laboratory Department of Electrical and Computer Engineering The Pennsylvania State University University Park Pennsylvania 16802 IBM General Technology Division East Fishkill Facility Hopewell Junction New York 12533

In this study the performance of reactive ion etching (RIE) and magnetically enhanced reactive ion etching (MERIE) processes in pregate oxidation etching of the field oxide are compared. The comparison is carried out through metal–oxide–semiconductor (MOS) characterization of oxides and interfaces formed on etched silicon surfaces. The results revealed differences in the outcome of RIE and MERIE processes with the latter displaying overall superior characteristics. MERIE induced surface damage is shallower, and is mostly removed during oxide growth. RIE damage propagates deeper into the Si bulk and still influences the MOS devices even after the top Si layers are converted into the oxide. The results obtained emphasize the importance of adequate cleaning of silicon surfaces following RIE/MERIE processes.

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Embedding of meshes on rotator graphs

Embedding of meshes on rotator graphs

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Midwest Symposium on Circuits and Systems (MWSCAS)

作者： S. Ponnuswamy V. Chaudhary Dept. of Electr. & Comput. Eng. Wayne State Univ. Detroit MI USA Parallel and Distributed Computing Laboratory Department of Electrical and Computer Engineering Wayne State University Detroit MI USA

A set of directed permutation graphs called rotator graphs were proposed as an alternative to the star and pancake graphs for multiprocessor interconnection networks. The rotator graphs have a smaller diameter than star and pancake graphs for the same number of nodes, while sharing the properties of star, pancake, and binary hypercubes like maximal fault tolerance, partitionability, etc. In this paper we develop a class of algorithms for recognizing undirected mesh structures in n-rotator graphs. The average dilation of the embeddings are very low as compared to the dilation of the embedding. These embeddings will be very useful for regular computations with bi-directional requirements, in addition to the irregular computations in n-rotator graphs. Most of the results presented here equally apply to another set of directed Cayley graphs, the cycle prefix digraphs.< >

关键词： Multiprocessor interconnection networks Hypercubes Bidirectional control Concurrent computing Fault tolerance Embedded computing Routing Application software Sorting computer vision

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TLM MODELING USING AN SIMD computer

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INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 1993年第4期6卷 299-304页

作者： TAN, CC FUSCO, VF The Queen's University of Belfast Department of Electrical & Electronic Engineering Ashby Building Stranmillis Road Belfast BT9 5AH U.K. Chun Chia Tan obtained a first-class honours degree from The Queen's University of Belfast. He was awarded an IEE prize for best final-year project. His current research interests include the modelling of electromagnetic fields using parallel processing techniques. At present Mr Tan is working as an electrical engineer in Malaysia. Vincent F. Fusco was educated at The Queen's University of Belfast where he obtained the degree of Ph.D. He has worked as a research engineer on short-range radar and radio telementry systems. Currently he is a Reader in Microwave Commnications in the School of Electrical Engineering and Computer Science The Queen's Univeristy of Belfast. His current research interests include non-linear microwave circuit simulation and concurrent programming techniques for electromagnetic field problems. He has acted as consultant to a number of major companies and has published numerous research papers in these areas. He is author of the bookMicrowave Circuits Analysis and Computer Aided Design(Prentice Hall 1987). Dr Fusco is a Chartered Electrical Engineer and a Member of the Institute of Electrical Engineers.

A major limitation of the transmission-line matrix (TLM) method used to solve Maxwell's equations is the long computation time required. The TLM scattering calculations involved can, however, be viewed as parallel in nature. This paper describes an effort to reduce computational time by using an SIMD, DAP multiprocessor computer employed to solve a two-dimensional TLM electromagnetic field formulation. A parallel algorithm based on the TLM scattering algorithm is designed and implemented using FORTRAN-PLUS Enhanced on an AMT DAP 510 machine. Here the connectivity of the DAP is exploited to simulate the intrinsic scattering behaviour on which the TLM algorithm relies. The results show that parallel processing on an SIMD machine such as the DAP is advantageous, especially for higher-order mesh sizes.

关键词： Electric lines

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SPECIFICATION AND ANALYSIS OF parallel DISTRIBUTED SOFTWARE AND SYSTEMS BY PETRI NETS WITH TRANSITION ENABLING FUNCTIONS

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IEEE TRANSACTIONS ON SOFTWARE engineering 1992年第3期18卷 252-261页

作者： PAPELIS, YE CASAVANT, TL Parallel Processing Laboratory Department of Electrical and Computer Engineering University of Iowa Iowa City IA 52242

This paper investigates a new approach for visually specifying parallel/distributed software using Petri Nets (PN's) extended with Transition Enabling Functions (TEF's). The approach is demonstrated to be useful in the specification of decision-making activities that control distributed computing systems. PN's are employed because of their highly visual nature that can give insight into the nature of the controller of such a system and because of their well-known analytical properties. In order to increase the expressive power of PN's, the extension of TEF's is used. The main focus of this paper is the specification and analysis of parallel/distributed software and systems. A key element of this approach is a set of rules derived to automatically transform such an extended net into a basic PN. Once the rules have been applied to transform the specification, well-known analytical methods can be used to investigate characteristic properties of the system and validate correct operation.

关键词： DISTRIBUTED SOFTWARE parallel SOFTWARE SOFTWARE SPECIFICATION parallel PETRI NETS TRANSITION ENABLING FUNCTIONS CONCURRENCY

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