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Communications and signal processing

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Full-Text Articles in Engineering

Algorithms For Enhancing Pattern Separability, Feature Selection And Incremental Learning With Applications To Gas Sensing Electronic Nose Systems , Robi Polikar Jan 2000

Algorithms For Enhancing Pattern Separability, Feature Selection And Incremental Learning With Applications To Gas Sensing Electronic Nose Systems , Robi Polikar

Retrospective Theses and Dissertations

Three major issues in pattern recognition and data analysis have been addressed in this study and applied to the problem of identification of volatile organic compounds (VOC) for gas sensing applications. Various approaches have been proposed and discussed. These approaches are not only applicable to the VOC identification, but also to a variety of pattern recognition and data analysis problems. In particular, (1) enhancing pattern separability for challenging classification problems, (2) optimum feature selection problem, and (3) incremental learning for neural networks have been investigated;Three different approaches are proposed for enhancing pattern separability for classification of closely spaced, or ...


Texture Representation Using Wavelet Filterbanks , Nam-Deuk Kim Jan 2000

Texture Representation Using Wavelet Filterbanks , Nam-Deuk Kim

Retrospective Theses and Dissertations

Texture analysis is a fundamental issue in image analysis and computer vision. While considerable research has been carried out in the texture analysis domain, problems relating to texture representation have been addressed only partially and active research is continuing. The vast majority of algorithms for texture analysis make either an explicit or implicit assumption that all images are captured under the same measurement conditions, such as orientation and illumination. These assumptions are often unrealistic in many practical applications;This dissertation addresses the viewpoint-invariance problem in texture classification by introducing a rotated wavelet filterbank. The proposed filterbank, in conjunction with a ...


Signal Processing And Image Restoration Techniques For Two-Dimensional Eddy Current Nondestructive Evaluation , Bing Wang Jan 1997

Signal Processing And Image Restoration Techniques For Two-Dimensional Eddy Current Nondestructive Evaluation , Bing Wang

Retrospective Theses and Dissertations

This dissertation presents a comprehensive study on the forward modeling methods, signal processing techniques, and image restoration techniques for two-dimensional eddy current nondestructive evaluation. The basic physical forward method adopted in this study is the volume integral method. We have applied this model to the eddy current modeling problem for half space geometry and thin plate geometry. To reduce the computational complexity of the volume integral method, we have developed a wavelet expansion method which utilizes the multiresolution compression capability of the wavelet basis to greatly reduce the amount of computation with small loss in accuracy. To further improve the ...


Invariance Transformations For Processing Nde Signals , Shreekanth Ammanji Mandayam Jan 1996

Invariance Transformations For Processing Nde Signals , Shreekanth Ammanji Mandayam

Retrospective Theses and Dissertations

The ultimate objective in nondestructive evaluation (NDE) is the characterization of materials, on the basis of information in the response from energy/material interactions. This is commonly referred to as the "inverse problem." Inverse problems are in general ill-posed and full analytical solutions to these problems are seldom tractable. Pragmatic approaches for solving them employ a constrained search technique by limiting the space of all possible solutions. A more modest goal is therefore to use the received signal for characterizing defects in objects in terms of the location, size and shape. However, the NDE signal received by the sensors is ...


Pattern Recognition And Image Processing Of Infrared Astronomical Satellite Images , Lun Xiong He Jan 1996

Pattern Recognition And Image Processing Of Infrared Astronomical Satellite Images , Lun Xiong He

Retrospective Theses and Dissertations

The Infrared Astronomical Satellite (IRAS) images with wavelengths of 60 [mu] m and 100 [mu] m contain mainly information on both extra-galactic sources and low-temperature interstellar media. The low-temperature interstellar media in the Milky Way impose a "cirrus" screen of IRAS images, especially in images with 100 [mu] m wavelength. This dissertation deals with the techniques of removing the "cirrus" clouds from the 100 [mu] m band in order to achieve accurate determinations of point sources and their intensities (fluxes). We employ an image filtering process which utilizes mathematical morphology and wavelet analysis as the key tools in removing the ...


Analysis And Synthesis Of Nonlinear Control Systems , Shan Lin Jan 1996

Analysis And Synthesis Of Nonlinear Control Systems , Shan Lin

Retrospective Theses and Dissertations

In this dissertation, regular nonlinear control systems of the form .x=X0(x)+[sigma]spi=1m uiXi(x) are considered. Necessary and sufficient conditions are given for a point to be reached from one of its entire neighborhoods in finite time by a piece-wise analytic feedback controller. Under such a feedback controller, the domain of attraction of the point is maximal. In particular, necessary and sufficient conditions on stabilization of a point or a periodic orbit in two dimension flat space are given. Moreover, practical examples are discussed and some interesting results are derived. Finally, when one dimensional systems are ...


Automated Image Inspection Using Wavelet Decomposition And Fuzzy Rule-Based Classifier , Zhong Zhang Jan 1995

Automated Image Inspection Using Wavelet Decomposition And Fuzzy Rule-Based Classifier , Zhong Zhang

Retrospective Theses and Dissertations

A general purpose image inspecting system has been developed for automatic flaw detection in industrial applications. The system has a general purpose image understanding architecture that performs local feature extraction and supervised classification. Local features of an image are extracted from the compactly supported wavelet transform of the image. The features extracted from the wavelet transform provide local harmonic analysis and multi-resolution representation of the image. Image segmentation is achieved by classifying image pixels based on features extracted within a local area near each pixel. The supervised classifier used in the segmentation process is a fuzzy rule-based classifier which is ...


Spline Network Modeling And Fault Classification Of A Heating Ventilation And Air-Conditioning System , Mathew Scaria Chackalackal Jan 1994

Spline Network Modeling And Fault Classification Of A Heating Ventilation And Air-Conditioning System , Mathew Scaria Chackalackal

Retrospective Theses and Dissertations

A spline network, that is an alternative to artificial neural networks, is introduced in this dissertation. This network has an input layer, a single hidden layer, and an output layer. Spline basis functions, with small support, are used as the activation functions. The network is used to model the steady state operation of a complex Heating Ventilation and Air-conditioning (HVAC) system. Real data was used to train the spline network. A neural network was also trained on the same set of data. Based on the training process, it is possible to conclude that when compared to artificial neural networks, the ...


Effects Of Randomly Rough Surfaces On Ultrasonic Inspection , Mehmet Bilgen Jan 1993

Effects Of Randomly Rough Surfaces On Ultrasonic Inspection , Mehmet Bilgen

Retrospective Theses and Dissertations

Surface finish of an industrial part affects its ultrasonic inspection and consequently the surfaces are often machined smooth before the evaluation. Ultrasonic inspection through smooth surfaces has been well studied and understood. A theoretical basis has been established for the characterization of interior cracks, voids and inclusions, and vast amount of literature exists. However, much less is known about quantitative ultrasonic inspection of such flaws in parts with rough surfaces, e.g. machine marks or "as-cast" surfaces. A question arises "When can an industrial part with randomly rough surfaces be inspected robustly using ultrasound?" This dissertation is aimed at answering ...


Image Analysis, Modeling, Enhancement, Restoration, Feature Extraction And Their Applications In Nondestructive Evaluation And Radio Astronomy , Yi Zheng Jan 1987

Image Analysis, Modeling, Enhancement, Restoration, Feature Extraction And Their Applications In Nondestructive Evaluation And Radio Astronomy , Yi Zheng

Retrospective Theses and Dissertations

The principal topic of this dissertation is the development and application of signal and image processing to Nondestructive Evaluation (NDE) and radio astronomy;The dissertation consists of nine papers published or submitted for publication. Each of them has a specific and unique topic related to signal processing or image processing in NDE or radio astronomy. Those topics are listed in the following. (1) Time series analysis and modeling of Very Large Array (VLA) phase data. (2) Image analysis, feature extraction and various applied enhancement methods for industrial NDE X-ray radiographic images. (3) Enhancing NDE radiographic X-ray images by adaptive regional ...