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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Study of Time-Interleaved SAR ADC andImplementation of Comparator for High DefinitionVideo ADC in 65nm CMOS Process

Qazi, Sara January 2010 (has links)
The Analog to Digital Converter (ADC) is an inevitable part of video AnalogFront Ends (AFE) found in the electronic displays today. The need to integratemore functionality on a single chip (there by shrinking area), poses great designchallenges in terms of achieving low power and desired accuracy.The thesis initially focuses upon selection of suitable Analog to Digital Converter(ADC) architecture for a high definition video analog front end. SuccessiveApproximation Register (SAR) ADC is the selected architecture as it scales downwith technology, has very less analog part and has minimal power consumption.In second phase a mathematical model of a Time-Interleaved Successive ApproximationRegister (TI-SAR) ADC is developed which emulates the behavior ofSAR ADC in Matlab and the errors that are characteristic of the time interleavedstructure are modeled.In the third phase a behavioral model of TI-SAR ADC having 16 channels and12 bit resolution, is built using the top-down methodology in Cadence simulationtool. All the modules were modeled at behavioral level in Verilog-A. The functionalityof the model is verified by simulation using signal of 30 MHz and clockfrequency of 300 MHz, using a supply voltage of 1.2 V. The desired SNDR (Signalto Noise Distortion ratio) 74 dB is achieved.In the final phase two architectures of comparators are implemented in 65nmtechnology at schematic level. Simulation results show that SNDR of 71 dB isachievable with a minimal power consumption of 169.6 μWper comparator runningat 300 MHz.NyckelordKeywords
112

The impact of adding front-of-package sodium content labels to grocery products: an experimental study

Goodman, Samantha January 2011 (has links)
A high sodium diet is a predominant risk factor for hypertension, which is in turn a major risk factor for cardiovascular disease. Canadians consume approximately twice the daily Adequate Intake of sodium, most of which comes from processed foods. Enhancing nutrition labelling for sodium in the form of front-of-package (FOP) labels may help consumers select healthier products. This experimental study examined the efficacy of 4 types of FOP nutrition labels on participant selection of low versus high sodium products. 430 adults from the Waterloo Region were randomly assigned to one of 5 experimental conditions: (1) a control condition with no FOP label; (2) a basic numeric FOP label; (3) a numeric FOP label with “high” and “low” sodium content descriptors; (4) a detailed Traffic Light (TL) label with colour coding, content descriptors and numeric information; and (5) a simple TL label that did not include numeric information. Participants were shown pairs of grocery products that varied primarily in sodium content, and asked to select a free product. Selection of the low versus high sodium product served as the primary behavioural outcome; rankings and ratings of the experimental labels were also examined. Regression models were used to determine the relative efficacy of the 4 labelling formats, as well as the socio-demographic and diet and health-related predictors of these outcomes. Results indicated that participants in the FOP conditions with “low” and “high” sodium content descriptors (conditions 3, 4 and 5) were significantly more likely to choose the low sodium product compared to the control group. The detailed TL was ranked as the most effective at helping participants select low sodium products; this label was also rated significantly higher than other formats in liking, understanding and believability. Product selection did not differ significantly across socio-demographic groups, suggesting that FOP labelling might reduce the disparity in the use and understanding of nutrition labels among groups of varying socioeconomic status. This study has important policy implications. Results suggest that FOP labels should include content descriptors, which add prescriptive value and may help consumers select healthier products by improving understanding. TL labels, which incorporate content descriptors and colour coding, are recommended for future FOP labelling initiatives.
113

Front end x-ray beam position monitors at the Canadian Light Source

Smith, Sheldon James 04 October 2006 (has links)
The development of X-ray Beam Position Monitors (XBPM) used on the Canadian Light Source front ends is described in this thesis, from the design concepts to the practical implementation and commissioning. Surveyed into position to provide a fiducialized point of origin for incoming synchrotron radiation, the primary purpose of the XBPM is to provide a measure of synchrotron beam motion. Currently XBPMs have been installed on three beamlines at the Canadian Light Source, a 2.9 GeV third generation synchrotron radiation source. Two of the XBPMs are comprised of chemical vapour deposition synthetic diamond blades coated with gold and installed on insertion device beamlines, while the third makes use of molybdenum blades for a dipole beamline. By incrementally scanning the blades of the XBPM through the synchrotron beam it is possible to determine the monitors� spatial resolution to beam motion. For the commissioned XBPM a typical spatial resolution of +/- 1 micron of beam motion was achieved; and the thermal power loading capacity has been tested to the 2/5 of maximum value. An independent white beam profiler, comprised of a converter crystal and image acquisition software, was constructed to corroborate the functionality of the XBPM.
114

Modeling Dissolution in Aluminum Alloys

Durbin, Tracie L 30 March 2005 (has links)
Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the sharp-interface method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum alloys when compared with published experimental results. The influence of inter-particle spacing is examined and shown to have a significant effect on dissolution kinetics. Finally, the impact of multiple particles of various sizes interacting in an aluminum matrix is investigated. It is shown that smaller particles dissolve faster, as expected, but influence the dissolution of larger particles through soft-impingement, even after the smaller particles have disappeared.
115

Design of Resonant Current Controller in Full stationary-frame for LCL-based Active Front-end Converter

Hu, Shang-hung 26 July 2010 (has links)
Thanks to development of power semiconductor devices and integrated circuits, active front-end converters with controllability of bidirectional power flow have become popular and viable in industrial applications. This thesis proposes an improved resonant current control for the active front-end converter with LCL filter. The proposed control consists of a band-pass filter tuned at fundamental frequency and various band-rejected filters resonant at harmonic frequencies to provide fundamental current tracking capability as well as enhance harmonic current rejection. Based on this algorithm, the active front-end converter can control dc voltage with unity power factor by sensing converter output current, LCL filter voltage and dc voltage. This approach also conducts harmonic current rejection under distorted line voltage with no phase-locked-loop used, which is the significant advantage in terms of phase lag of frame transformation and computing effort of digital signal processing. Current tracking performance and harmonic rejection capability of the proposed method are verified based on frequency-domain analysis. Computer simulations and experimental results are also implemented to validate effectiveness.
116

Lane-Based Front Vehicle Detection and Its Acceleration

Chen, Jie-Qi 02 January 2013 (has links)
Based on .Net Framework4.0 development platform and Visual C# language, this thesis presents various methods of performing lane detection and preceding vehicle detection/tracking with code optimization and acceleration to reduce the execution time. The thesis consists of two major parts: vehicle detection and tracking. In the part of detection, driving lanes are identified first and then the preceding vehicles between the left lane and right lane are detected using the shadow information beneath vehicles. In vehicle tracking, three-pass search method is used to find the matched vehicles based on the detection results in the previous frames. According to our experiments, the preprocessing (including color-intensity conversion) takes a significant portion of total execution time. We propose different methods to optimize the code and speed up the software execution using pure C # pointers, OPENCV, and OPENCL etc. Experimental results show that the fastest detection/tracking speed can reach more than 30 frames per second (fps) using PC with i7-2600 3.4Ghz CPU. Except for OPENCV with execution rate of 18 fps, the rest of methods have up to 28 fps processing rate of almost the real-time speed. We also add the auxiliary vehicle information, such as preceding vehicle distance and vehicle offset warning.
117

Sub-Nyquist Rate Sampling Data Acquisition Systems Based on Compressive Sensing

Chen, Xi 2011 May 1900 (has links)
This dissertation presents the fundamental theory and design procedure of the sub-Nyquist rate sampling receiver front-end that exploits signal sparsity by employing Compressive Sensing (CS) techniques. The CS receiver serves as an Analog-to-Information Conversion (AIC) system that works at sampling rates much lower than the Nyquist rate. The performance of a parallel path CS front-end structure that employs current mode sampling techniques is quantified analytically. Useful and fundamental design guidelines that are unique to CS are provided based on the analytical tools. Simulations with IBM 90nm CMOS process verify the theoretical derivations and the circuit implementations. Based on these results, it is shown that instantaneous receiver signal bandwidth of 1.5 GHz and 44 dB of signal to noise plus distortion ratio (SNDR) are achievable in simulations assuming 0.5 ps clock jitter is present. The ADC and front-end core power consumption is estimated to be 120.8 mW. The front-end is fabricated with IBM 90nm CMOS process, and a BPSK sub-Nyquist rate communication system is realized as a prototype in the testing. A 1.25 GHz reference clock with 4.13 ps jitter variance is employed in the test bench. The signal frequency, phase and amplitude can be correctly reconstructed, and the maximum signal SNR obtained in the testing is 40 dB with single tone input and 30 dB with multi-tones test. The CS system has a better FOM than state-of-art Nyquist rate data acquisition systems taking into account the estimated PLL power.
118

An FIFO Memory Design for Data Exchange Bus and Analog Front-end of Digital Cordless Headset Baseband Controller

Chen, Yi-Wei 24 June 2002 (has links)
Three different chip design topics associated with their respective applications are proposed in this thesis. The first topic is the implementation of an FIFO memory design for 8-to-32 data exchange bus. An FIFO memory architecture is proposed to be utilized in data exchange between processing units which possess non-homogeneous bus widths. Neither arbiter logics nor modules are required in such a design to determine input sequences or output sequences. Hence, the delay is drastically shortened. The second topic is focused on the implementation of an analog front-end of digital cordless headset baseband controller. The integrated analog and digital interface IC provides an interface for analog and digital communication. It converts an analog signal into an 8-bit digital signal, which will be processed by the baseband controller. It also converts an 8-bit digital voice data into an analog voice signal. In addition, a built-in oscillator is included in the design, which provides a global clock signal. The third topic is to carry out an DC/DC converter with a built-in voltage detector. The converter can convert 1.5V input voltage to 2.7V output voltage. A portable system can use only one single battery to power on by this circuit. It also contains a voltage detector to indicate whether the output voltage meets the pre-determined level.
119

A 200-MHz fully-differential CMOS front-end with an on-chip inductor for magnetic resonance imaging

Ayala, Julio Enqrique, II 25 April 2007 (has links)
Recently, there is a growing interest in applying electronic circuit design for biomedical applications, especially in the area of nuclear magnetic resonance (NMR). NMR has been used for many years as a spectroscopy technique for analytical chem- istry. Previous studies have demonstrated the design and fabrication of planar spiral inductors (microcoils) that serve as detectors for nuclear magnetic resonance mi- crospectroscopy. The goal of this research was to analyze, design, and test a prototype integrated sensor, which consisted of a similar microcoil detector with analog components to form a multiple-channel front-end for a magnetic resonance imaging (MRI) system to perform microspectroscopy. The research has succeeded in producing good function- ality for a multiple-channel sensor. The sensor met expectations compared to similar one-channel systems through experiments in channel separation and good signal-to- noise ratios.
120

Satellite observations and numerical simulations of jet-front gravity waves over North America and North Atlantic Ocean

Zhang, Meng 10 October 2008 (has links)
In this study, a month-long simulation of gravity waves over North America and North Atlantic Ocean is performed using the mesoscale model MM5 for January 2003, verified with Advanced Microwave Sounding Unit-A (AMSU-A) radiance observations in the upper troposphere and lower stratosphere. According to the monthly mean statistics, four regions of strong gravity wave activities are found both in the simulation and the AMSU-A observations: northwestern Atlantic, Appalachian Mountains, Rocky Mountains and Greenland, respectively. Those over the northwestern Atlantic Ocean are strongly associated with the midlatitude baroclinic jet-front systems, while the other three regions are apparently collocated with high topography. Imbalance diagnosis and numerical sensitivity experiments of a strong gravity wave event during January 18-22 show that the gravity waves are strongly linked to the unbalanced flow in the baroclinic jet-front system. The gravity waves are usually radiated from the upper tropospheric jet exit region with maximum nonlinear balance equation residual ( Δ NBE; key indicator of flow imbalance), distinctly different from other surface sources. Flow imbalance related strongly to tropopause folding and frontogenesis of the large-scale background flow. Similar wave characteristics are simulated in experiments with different microphysics and grid resolutions. The Δ NBE is again shown to be a good predictor for jet-front related gravity waves, suggesting its potential application to gravity wave parameterizations for global and climate models.

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