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Full-Text Articles in Engineering

Image Fusion Using Multi-Resolution Decomposition And Lmmse Filter , Jaewon Yim Jan 1995

Image Fusion Using Multi-Resolution Decomposition And Lmmse Filter , Jaewon Yim

Retrospective Theses and Dissertations

The subject of data fusion utilizing heterogeneous sensors has received significant attention in recent years. Each of the sensors provides a limited perspective of the desired information. A heterogeneous sensor environment combined with a procedure for synergistically combining data from each of the transducers can potentially lead to a more comprehensive and accurate estimate of the desired information. An example of a field that can profit from the application of data fusion techniques is the area of nondestructive evaluation (NDE);This dissertation is concerned with developing efficient image fusion techniques for NDE applications. This dissertation begins with a brief description ...


Nde Data Fusion Using Phenomenological Approaches , Kai Sun Jan 1995

Nde Data Fusion Using Phenomenological Approaches , Kai Sun

Retrospective Theses and Dissertations

Data fusion techniques are beginning to attract considerable attention. In the NDE context, such techniques can be used to combine information from two or more NDE test methods to improve the probability of detection and enhance characterization results. An example of such an application involves the fusion of eddy current and ultrasonic NDE data. The eddy current phenomena relies on the diffusion process to propagate energy. Ultrasonic phenomena, in contrast, rely on wave propagation. The manner in which the energy interacts with the material under test is fundamentally different. It can therefore be argued that each test method provides a ...


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 ...


Modeling Of The Head-Related Transfer Functions For Reduced Computation And Storage , Charles Duncan Lueck Jan 1995

Modeling Of The Head-Related Transfer Functions For Reduced Computation And Storage , Charles Duncan Lueck

Retrospective Theses and Dissertations

The synthesis of three-dimensional sound via headphones generally requires the implementation of rather complex filters based on the head-related transfer functions (HRTFs), direction-specific transfer functions which simulate the transformation of sound pressure between a sound source and the eardrums of the listener. Current implementations generally rely on FIR filtering techniques, resulting in high computational complexity. The main objective of this work was to develop a set of computationally efficient filters which would be capable of emulating the head-related transfer functions. To accomplish this objective, a modification of conventional system modeling techniques through the application of psychoacoustic principles has been applied ...


New Ultrasonic Signal Processing Techniques For Nde Applications , Myung-Hyun Yoon Jan 1994

New Ultrasonic Signal Processing Techniques For Nde Applications , Myung-Hyun Yoon

Retrospective Theses and Dissertations

New ultrasonic signal processing techniques have been developed for nondestructive evaluation (NDE) applications. This dissertation has two parts. The first part is about the application of the wavelet transform to ultrasonic flaw detection. Wavelet transform is a newly developed signal analysis tool that handles time-localized signals such as an ultrasonic flaw signal quite well. A wavelet transform based signal processing technique has been developed which uses only partial knowledge of the flaw signal waveform that may be obtained from a reference experiment. The detection performance of the proposed technique is found to be comparable to that of the matched filter ...


Some New Developments In Image Compression , Keshi Chen Jan 1994

Some New Developments In Image Compression , Keshi Chen

Retrospective Theses and Dissertations

This study is divided into two parts. The first part involves an investigation of near-lossless compression of digitized images using the entropy-coded DPCM method with a large number of quantization levels. Through the investigation, a new scheme that combines both lossy and lossless DPCM methods into a common framework is developed. This new scheme uses known results on the design of predictors and quantizers that incorporate properties of human visual perception. In order to enhance the compression performance of the scheme, an adaptively generated source model with multiple contexts is employed for the coding of the quantized prediction errors, rather ...


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 ...


Optimal Fir Filter Design , Michael Zacharia Komodromos Jan 1993

Optimal Fir Filter Design , Michael Zacharia Komodromos

Retrospective Theses and Dissertations

The design of Finite Impulse Response (FIR) digital filters that considers both phase and magnitude specifications is investigated. This dissertation is divided into two parts. In Part I we present our implementation of an algorithm for the design of minimum phase filters. In Part II we investigate the design of FIR filters in the complex domain and develop a new powerful design method for digital FIR filters with arbitrary specification of magnitude and phase;Part I considers the design of minimum-phase filters. The method presented uses direct factorization of the transfer function of a companion Parks-McClellan linear-phase filter of twice ...


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 ...


Three-Dimensional Flaw Reconstruction Using A Real-Time X-Ray Imaging System , Edward Raymond Doering Jan 1992

Three-Dimensional Flaw Reconstruction Using A Real-Time X-Ray Imaging System , Edward Raymond Doering

Retrospective Theses and Dissertations

A system has been developed for making three-dimensional flaw measurements in materials using a real-time X-ray imaging laboratory. This environment affords precise control over all positional variables, offers multiple degrees of freedom for sample movement, and the continuous nature of the real-time image eliminates ambiguity in determining correspondence points among multiple views of the sample. This system is based on film stereography in which two stereo projections are obtained of a sample either by translating the X-ray source or by translating the sample. The three-dimensional coordinates of features of interest such as crack endpoints and centroids of void-like flaws are ...


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 ...