Abstract: This thesis is concerned with the acquisition of body signals using a sampling system. A typical application is the recording of the electrocardiogram (ECG). It is proposed to sample the input signal at different rates, depending on the momentary signal content. If the input signal has large voltage variation, it is sampled at a high rate. During periods of small variation, the signal is sampled at a lower frequency to save both memory and power. An analog controller to control the clock rate is proposed and implemented. The analog controller decides the sample frequency (high rate or low rate) depending on the input signal. The analysis of the proposed system is presented in this thesis. Furthermore, a working prototype is implemented using discrete components on a PCB. The measured results show a significant reduction in the average sample frequency and data rate of 50% and 35%, respectively. Finally, the critical analog circuit blocks of the system suitable for integration on chip are proposed and implemented in a 0.35£gm CMOS process. Measured results are reported to confirm the functionality of the blocks.

High-pass filtering has been shown to be a promising method for edge detection in optical scanning holography. By using a circular function as a pupil for the system, the radius of the circle can be varied to block out different ranges of frequencies. Implementing this system in simulation yields an interesting result, however. As the radius increases, a singular edge can split off into two edges instead. To understand the specific conditions under which this split occurs, Airy pattern filtering and single-sided filtering were implemented to analyze the results from the original high-pass simulation. These methods were tested with different input objects to assess any common patterns. Ultimately, no definitive answer was found, as Airy pattern filtering resulted in inconsistent results across different input objects, and single-sided filtering does not completely isolate the edge. Nonetheless, the documented results may aid a future understanding of this phenomenon. / Master of Science / Holograms are three-dimensional recordings of an object, reminiscent of how a photograph records a two-dimensional image of an object. Detecting edges in images and the reconstructed images from holograms can help us identify objects within the recorded image or hologram. In computer vision, common edge detection techniques involve analyzing the image's spatial frequency, or changes in relative intensity over space. One such technique is high-pass filtering, in which lower spatial frequencies are blocked out. High-pass filtering can also be applied to holographic imaging systems. However, when applying high-pass filtering to a holographic system, detected edges can split into two as higher frequencies are filtered out. This thesis examines the conditions for why this split-edge phenomenon occurs by modifying the original recorded object and the filtering mechanism, then analyzing the resultant holograms. While the results did not give a conclusive answer, they have been documented for the purpose of further research.

Constant False Alarm Rate (CFAR) Processors are important for applications where thousands of detection tests are made per second, such as in radar. This thesis introduces a new method for CFAR threshold estimation that is particularly applicable to sound source detection with distributed microphone systems. The novel CFAR Processor exploits the near symmetry about 0 for the acoustic pixel values created by steered-response coherent power in conjunction with a partial whitening preprocessor to estimate thresholds for positive values, which represent potential targets. To remove the low frequency components responsible for degrading CFAR performance, fixed and adaptive high-pass filters are applied. A relation is proposed and it tested the minimum high-pass cut-off frequency and the microphone geometry. Experimental results for linear, perimeter and planar arrays illustrate that for desired false alarm (FA) probabilities ranging from 10-1 and 10-6, a good CFAR performance can be achieved by modeling the coherent power with Chi-square and Weibull distributions and the ratio of desired over experimental FA probabilities can be limited within an order of magnitude.

This work introduces fundamental knowledge of EMI, and presents three basic features correlated to EMI susceptibility: nonlinear distortion, asymmetric slew rate (SR) and parasitic capacitance. Different existing EMI-resisting techniques are analyzed and compared to each other in terms of EMI-Induced input offset voltage and other important specifications such as current consumption. In this work, EMI-robust analog circuits are proposed, of which the architecture is based on source-buffered differential pair in the previous publications. The EMI performance of the proposed topologies has been verified within a test IC which was fabricated in NCSU 0.5um CMOS technology. Experimental results are presented when an EMI disturbance signal of 400mV and 800mV amplitude was injected at the input terminals, and compared with a conventional and an existing topology. The tested maximal EMI-induced input offset voltage corresponds to -222mV for the new structure, which is compared to -712mV for the conventional one and -368mV for the one using existing source-buffered technique in literature. Furthermore the overall performances of the circuits such as current consumption or input referred noise are also provided with the corresponding simulation results.

The safety concern of aging aircraft is a rising issue in terms of both safety and cost. An aircraft structure failure during flight is unacceptable. A method needs to be developed and standardized to test the integrity of both commercial and military aircrafts. The current method to test the structure of an aircraft requires the aircraft to be taken out of service for inspection; this is costly due to the inspection required to be performed and the lost use from downtime. A novice idea of an on-site structural health monitoring (SHM) system has been proposed to test the integrity of aircraft structure. An on-site system is a system that can be used to perform inspection on an aircraft simultaneously while the aircraft is in use. This SHM system uses the principles of active lamb wave and passive acoustic emission through the use of piezoelectric sensors as the sensing elements. Piezoelectric sensors can be used both as an input device and as a sensing element. This research focuses on the development of the major data acquisition electronic components of the system. These components are charge amplifier, high pass filter, low pass filter and line driver. A charge amplifier converts a high impedance signal to a low impedance signal. A high pass filter attenuates the low frequency content of a signal, while a low pass filter attenuates the high frequency content of a signal. A line driver converts a low current signal to a high current signal. All of these components need to operate up to a frequency of 2 MHz. Off-the-shelf electronics will be used for prototyping as custom components will not be feasible at this point of the research. / Master of Science

In recent years, as the availability of remote sensing imagery of varying resolution has increased, merging images of differing spatial resolution has become a significant operation in the field of digital remote sensing. This practice, known as data fusion, is designed to enhance the spatial resolution of multispectral images by merging a relatively coarse-resolution image with a higher resolution panchromatic image of the same geographic area. This study examines properties of fused images and their ability to preserve the spectral integrity of the original image. It analyzes five current data fusion techniques for three complex scenes to assess their performance. The five data fusion models used include one spatial domain model (High-Pass Filter), two algebraic models (Multiplicative and Brovey Transform), and two spectral domain models (Principal Components Transform and Intensity-Hue-Saturation). SPOT data were chosen for both the panchromatic and multispectral data sets. These data sets were chosen for the high spatial resolution of the panchromatic (10 meters) data, the relatively high spectral resolution of the multispectral data, and the low spatial resolution ratio of two to one (2:1). After the application of the data fusion techniques, each merged image was analyzed statistically, graphically, and for increased photointerpretive potential as compared with the original multispectral images. While all of the data fusion models distorted the original multispectral imagery to an extent, both the Intensity-Hue-Saturation Model and the High-Pass Filter model maintained the original qualities of the multispectral imagery to an acceptable level. The High-Pass Filter model, designed to highlight the high frequency spatial information, provided the most noticeable increase in spatial resolution. / Master of Science

The separation and reattachment of the suction surface boundary layer in a low pressure turbine is characterized using large-eddy simulation at Re=68,000 based on freestream velocity and suction surface length. A high pass filtered Smagorinsky model is used for modeling the sub-grid scales. The onset of time mean separation is at s=so = 0:61 and reattachment at s=so = 0:81, extending over 20% of the suction surface. The boundary layer is convectively unstable with a maximum reverse flow velocity of about 13% of freestream. The breakdown to turbulence occurs over a very short distance of suction surface which is followed by reattachment. Detailed investigations into the structure and kinematics of the bubble and turbulence statistics are presented. The vortex shed from the bubble, convects downstream and interacts with the trailing edge vortices increasing the turbulence intensity. On the suction side, dominant hairpin structures near the transitional and turbulent flow regime are observed. These hairpin vortices are carried by the freestream even downstream of the trailing edge of the blade with a possibility of reaching the next stage. Longitudinal streaks that evolve from the breakdown of hairpin vortices formed near the leading edge are observed on the pressure surface.

本研究所要討論的是如何以局部區域的數值高程模型資料辨識出所在整體地形的相對應位置。數值高程模型是以網格式的方式描述地表上連續性的起伏變化，以二維陣列儲存地表高度的資料，包含三度空間的特性。 我們從區域地形萃取出線性特徵與點特徵，分別為水系河段與地形上較明顯的凸點與凹點，以水系作為識別每一區域地形的“指紋”，對於地形變化小或河段特徵不明顯之區域尋找其特徵點，配合相關地形參數與整體地形進行比對，並對不同之特徵採用不同比對演算法。我們以物件化的方式表達水系河段與特徵點，將許多圖層的資訊整合於物件中，除了方便資料的管理，也加快了比對的效率。實驗結果顯示，應用此兩種特徵值作為辨識地形依據，可有效辨識出正確位置，也節省許多不必要的比對時間。 / The main objective of this thesis is to identify a terrain using partial Digital Elevation Model (DEM) information. DEM is one of the most commonly used data representation models used in Geographical Information Systems. It is a digital model with an array of uniformly spaced elevation data in raster format. One can use DEM to analyze terrain measures including slope, aspect, and other features. In the thesis, we use hydrology analysis to extract the stream networks and use terrain parameter analysis to compute terrain features from the DEM of a small region. This information can be used as the “fingerprints” of the terrain and then compare them with the “fingerprints” in the whole data base in order to identify or to locate the correct location of the region. The KMP string matching algorithm is used to speed up the matching process. Measurements extracted from DEM through hydrology analysis may not provide significant terrain information for the identification purpose. In this case, other mechanism such as VIP node and algorithm are used to facilitate the identification process. We embed object oriented concepts in actual implementation. The experimental results show that our mechanism works successfully and the time used in the identification process reduced significantly.

No description available.

Dans cette thèse, les recherches ont été menées à des niveaux d'abstraction différents pour optimiser le fonctionnement du modulateur ΣΔ passe-haut (PH). Une approche « top-down » est adoptée pour atteindre cet objectif. Au niveau de l'architecture du récepteur RF, le nouvellement créé récepteur Fs/2 est sélectionné pour sa grande compatibilité avec modulateur ΣΔ PH comparé aux architectures de réception: zéro-IF et faible-IF. Après avoir défini la topologie du récepteur, l'architecture du modulateur ΣΔ est adressée. Nous proposons une nouvelle architecture du deuxième ordre dont la fonction de transfert du signal est unitaire. Elle est plus avantageuse que d'autres topologies en termes de complexité et de performance. Puisque le modulateur de second ordre est incapable de fournir les performances requises, les structures en cascade ou MASH pour l'opération PH sont explorées. La topologie GMSCL (Generalized Multi-Stage Closed Loop) est choisie et une technique récemment proposée est appliquée pour linéariser le CNA de retour. En plus, cette technique augmente la plage dynamique du convertisseur. Ensuite, après une analyse comparative approfondie, le meilleur filtre HP est choisie pour ce modulateur. Il a les avantages d'avoir une basse consommation, une superficie réduite et un bruit moins important. Enfin, l'architecture GMSCL PH proposée est validée en CMOS 65nm. Les applications visées sont l'UMTS avec 3.84MHz bande de conversion à 80 dB de la plage dynamique et WiMAX avec 25MHz de bande passante à 52dB de dynamique.