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Full-Text Articles in Engineering

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 ...