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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.
91

MRI-Compatible Pneumatic Actuation Control Algorithm Evaluation and Test System Development

Wang, Yi 23 September 2010 (has links)
"This thesis presents the development of a magnetic resonance imaging (MRI) compatible pneumatic actuation test system regulated by piezoelectric valve for image guided robotic intervention. After comparing pneumatic, hydraulic and piezoelectric MRI-compatible actuation technologies, I present a piezoelectric valve regulated pneumatic actuation system consisted of PC, custom servo board driver, piezoelectric valves, sensors and pneumatic cylinder. This system was proposed to investigate the control schemes of a modular actuator, which provides fully MRI-compatible actuation; the initial goal is to control our MRI-compatible prostate biopsy robot, but the controller and system architecture are suited to a wide range of image guided surgical application. I present the mathematical modeling of the pressure regulating valve with time delay and the pneumatic cylinder. Three different sliding mode control (SMC) schemes are proposed to compare the system performance. Simulation results are presented to validate the control algorithm. Practical tests with parameters determined from simulation show that the system performance attained the goal. A novel MRI- compatible locking device for the pneumatic actuator was developed to provide safe lock function as the pneumatic actuator fully stopped."
92

PERFORMANCE OF THE GROUT CURTAIN AT THE KENTUCKY RIVER LOCK AND DAM NO. 8

Hatton, Robert C. 01 January 2018 (has links)
Karst bedrock conditions and deterioration of the lock and dam structures have resulted in significant leakage through, underneath, and around Lock and Dam No. 8 on the Kentucky River. During severe droughts, the water surface in Pool No. 8 has been observed to drop below the crest of the dam, resulting in water supply shortages and water quality issues for surrounding communities reliant on the pool. Presently, the primary purpose of Lock and Dam No. 8 is water supply. Pool No. 8 is currently where the cities of Nicholasville (Jessamine County, KY) and Lancaster (Garrard County, KY) draw their water. Due to the age and condition of the structures, and the criticality of the retained water supply, the project Owner commissioned a replacement dam to be built. One major component of the replacement dam was a foundation improvement program. The foundation improvement program was designed to address the karst bedrock conditions at the site. The foundation improvements included a secant pile cutoff wall and a double-row grout curtain. The grout curtain at Lock and Dam No. 8 was evaluated based on the metrics presently available.
93

Data acquisition unit for low-noise, continuous glucose monitoring

Cooley, Daniel Warren 01 May 2012 (has links)
As the number of people with diabetes continues to increase, research efforts improving glucose testing methods and devices are under way to improve outcomes and quality of life for diabetic patients. This dissertation describes the design and testing of a Data Acquisition Unit (DAU) providing low noise photocurrent spectra for use in a continuous glucose monitoring system. The goal of this research is to improve the signal to noise ratio (SNR) of photocurrent measurements to increase glucose concentration measurement accuracy. The glucose monitoring system consists of a portable monitoring device and base station. The monitoring device measures near infrared (IR) absorption spectra from interstitial fluid obtained by microdialysis or ultrafiltration probe and transmits the spectra to a base station via USB or a ZigBee radio link. The base station utilizes chemometric calibration methods to calculate glucose concentration from the photocurrent spectra. Future efforts envisage credit card-sized monitoring devices. The glucose monitor system measures the optical absorbance spectrum of an interstitial fluid (ISF) sample pumped through a fluid chamber inside a glucose sensor. Infrared LEDs in the glucose sensor illuminate the ISF sample with IR light covering the 2.2 to 2.4 micron wavelength region where glucose has unique features in its absorption spectrum. Light that passes through the sample propagates through a linearly variable bandpass filter and impinges on a photodiode array. The center frequency of the variable filter is graded along its length such that the filter and photodiode array form a spectrometer. The data acquisition unit (DAU) conditions and samples photocurrent from each photodiode channel and sends the resulting photocurrent spectra to the Main Controller Unit (MCU). The MCU filters photocurrent samples providing low noise photocurrent spectra to a base station via USB or Zigbee radio link. The glucose monitoring system limit of detection (LOD) from a single glucose sensor wavelength is 5.8 mM with a system bandwidth of 0.00108 Hz. Further analysis utilizing multivariate calibration methods such as the net analyte signal method promise to reduce the glucose monitoring system LOD approaching a clinically useful level of approximately 2 mM.
94

The Determinants of Customer Perceptions in a Dynamic Business Environment: An Exploratory Analysis of the ASP Business Model

Liang, Yan-Mei (AMY) January 2008 (has links)
Outsourcing attracted much attention in 1989 when Kodak outsourced its data center operation to IBM (International Business Machines Corp.). Nowadays, this strategy has become more popular. At the beginning of this century, the ASP (Application Service Provider) model was considered one of the typical solutions of Internet-based IT (Information Technology) outsourcing. Although this model has been transformed and renamed (e.g. SaaS - Software as a Service), the principle concept of providing IT service through the Internet or wide area network is still there. This study attempts to explore the determinants of customer perception of Internet-based IT outsourcing by obtaining a comprehensive understanding of the ASP model. The research dimensions not only include factors affecting users' perception of service quality but also ASP business position (i.e. the firm origin of ASP and its provider type) and services utilized by the customers. Through the study of firm history, two important theoretical themes of this research - path-dependence and Ansoff's product/ market growth matrix - are taken account of in exploring the influence of the determinants. Web-based questionnaire survey research is conducted together with a documentation study to collect data. Targeting the customers of the top 50 ASPs selected by ASPnews.com during the period 2001-2004, the researcher contacted 597 potential respondents, and 196 responses were returned. The valid sample consisted of 175 responses, and 124 of them not only provided full information for satisfaction evaluation but also the information for tracking their ASP vendors' business position. The GLM (General Linear Model) and the Pearson correlation coefficient were the major statistical approaches used to evaluate the survey data for developing a structural model. The research findings indicated that the factors associated with service competitiveness, such as capability and performance, reliability and trustworthiness, affordability, integration and customization, have positive effects on customer perceived satisfaction; whereas lock-in has a negative effect. More specifically, the origin of the ASP firm has a direct effect on capacity and performance, and also directly influences the use of IT adoption services. Based on this finding, a descriptive analysis and qualitative research shows that two mechanisms for path-dependence - existing expertise and perceived expertise - can affect the satisfaction level of capacity and performance of ASP services. On the other hand, provider type has a direct effect on affordability and also directly influences the use of facility supporting services. On this basis, another two mechanisms for path-dependence - transaction cost and standardization - can indirectly impact customer's perception of this business model via affordability. In addition to those major findings, some other determinants (e.g. software applications, brand of applications, and intensity of service used) were also identified in this study. The study result can be used for theoretical understanding about the determinants of ASP customer's perception. It not only indicates a new perspective to enhance the current body of research on this topic, but can also be more broadly applied to any fast-growth firm, rapid-change business, or technology intensive industry. Acknowledgements I would like to sincerely thank the following people for their contribution to this research project. Dr. Scott Koslow, my chief supervisor, for his continued encouragement, patience and guidance to ensure the completion of this project. His speciality in statistics has provided appropriate and valuable guidance in the data analysis for my research. Dr. Steven Lim, my second supervisor, for his advice, coherence, and support over the years. I also appreciate his constructive comments on my drafts and the shaping of my research. Dr. Bob McQueen and Dr. Jim Corner, for their assistance and advice in the early stages of my study. My parents, Yu-Ho and Lee-Chiung Liang, and my brother Ken, my sisters Annie, Eva, and Nancy, my brothers-in-law, J.C. and Chen, and Alice, my sister-in-law, for their emotional support throughout the length of my study. I also thank Bessie, my best friend for her assistance in data collection and her loving support, as well as Ted, Kevin, Mark, Frank, and Shirley, my study mates for their encouragement and friendship. Special thanks goes to Dr. Kuang-Ya Wang, the principal of Yu Da High School of Commerce and Home Economics, Taiwan, and also to the staff over there for their concern and assistance in data collection. Most importantly, my heartfelt appreciation goes to Warren, my husband. I am deeply grateful to him for his understanding, patience, and practical help. Without his enduring support I could not have done this study. Finally, my thanks and gratitude goes to those people who patiently answered my survey questionnaire as their kind assistance made it possible to complete this research.
95

A Methodology to Calculate the Time-Varying Flow Through a Hydraulic Structure Connecting Two Water Bodies

Zigic, Sasha, n/a January 2005 (has links)
Hydraulic lock structures have been used for hundreds of years to control and maintain water levels in waterways. The most common are gated water regulation structures used to catch and divert water, and form an essential and critical part of many flood control and agricultural schemes. Although there are clear economic advantages to building the structures, they can contribute to major water quality problems for the waterways they influence (i.e. increased residence times and a change in mixing ability). Further, in most cases, the methods previously used to assess how the structures and their operations influence the flow regimes between the two connected systems were limited, thus hydraulic designers rely on simple formulations, existing literature and experience. Consequently, the objectives of this thesis were to undertake a detailed field study and develop a methodology and computer simulation tool to calculate the flow through a hydraulic structure connecting two water bodies so that future designs can be undertaken based upon sound knowledge. To demonstrate the outcomes of this thesis, the methodology and model were applied to an existing hydraulic structure (referred to as Structure C). Structure C is used to connect and exchange water between the tidally dominated section of the Nerang River estuary and an artificial lake system (Burleigh Lakes) on the Gold Coast, Australia. The gates of this structure open four times each day (once during each semi-diurnal tidal phase) and remain open for a period of 2 hours, allowing alternative and partial exchange between the two water bodies. To gain a better understanding of the dynamics of each waterbody under the influence of the structure, a series of detailed field experiments were initially undertaken to understand and quantify the exchange of water and its mixing ability. Tide gauges deployed within the lake indicated a water level change during each opening of up to 22 cm, equating to 413,600 m3 of water entering the lake over the 2 hour discharge period. Salinity profiles showed that the structure permitted the exchange of saline and freshwater between the two systems, during each tidal cycle, in turn maintaining the lake system as a saline (brackish environment). However, the field study also revealed that the controlled exchange of water between the systems perpetuated a permanently stratified environment on both sides of the structure. To simulate the flow dynamics influenced by Structure C, new routines were incorporated into an existing hydrodynamic model (BFHYDRO) within the model's grid and computational code, as part of this thesis. To achieve this, the flow in and out of the hydraulic structure cell (used to represent the hydraulic structure's location within the model grid) was calculated entirely from the local water level gradients on either side of the structure at each time-step, and not prescribed. This was found to be essential for complex tidally-dominated systems, such as the Nerang River. Routines were also developed to replicate the opening and closing times of the gates. Following the development of the methodology, the hydraulic structure cells were tested and applied to simulate the flow through Structure C and the complex exchange between the estuary and lake, in 2 and 3-dimensions. Tests indicated that the opening and closing times of the gates and the calibration of the discharge coefficient (which forms part of the broad-crested weir formula) were the most sensitive parameters to ensure the correct volume of water exchange between the two systems. Statistically, the model-predicted results compared very well with available surface elevation data within the estuary and lake, and thus, quantified the ability of the hydraulic structure cells to simulate the flux between the estuary and lake for each opening. Following the model validation process, results from the existing configuration were compared with hypothetical design alternatives and are documented herein. Further, part of the thesis also explored a practical and effective computer based learning strategy to introduce and teach hydrodynamic and water quality modelling, to the next generation of undergraduate engineering students. To enhance technology transfer a computer based instructional (CBI) aid was specifically developed to assist with the setup, execution and the analysis of models' output, in small easy steps. The CBI aid comprised of a HTML module with links to recorded Lotus Screen cam movie clips. The strategy proved to be a useful and effective approach in assisting the students to complete the project with minimum supervision, and acquire a basic understanding of water quality modelling. Finally, it is anticipated that this new modelling capability and the findings detailed herein will provide managers with a valuable tool to assess the influence of these structures on water circulation for present and future operations within the region. This model can also be set up at other sites to pre-assess various design configurations by predicting changes in current flows, mixing and flushing dynamics that a particular design might achieve, and assist with the selection process before the final selection and construction.
96

5 GHz Phase Lock Loop with Auto Band Selection

Chen, Ming-Jing 06 August 2007 (has links)
This thesis presents the CMOS integer-N frequency synthesizer for 5 GHz WCDMA applications with 1.8V power supply. The frequency synthesizer is fabricated in a TSMC 0.18£gm CMOS 1P6M technology process. The frequency synthesizer consists of a phase-frequency detector, a charge pump, a low-pass loop filter, a voltage control oscillator, an auto-band selection, and a pulse-swallow divider. In pulse-swallow divider, this thesis use true single phase clock DFF proposed by Yuan and Svensson to work on high frequency region and to save the circuit area and power. This thesis also proposes an auto-band selection circuit to control the output frequency more precise and easier, and it can also reduce the frequency drift effect caused by technology process or temperature variation.
97

Scalable and Transparent Parallelization of Multiplayer Games

Simion, Bogdan 15 February 2010 (has links)
In this thesis, we study parallelization of multiplayer games using software Transactional Memory (STM) support. We show that STM provides not only ease of programming, but also better scalability than achievable with state-of-the-art lock-based programming for this realistic high impact application. We evaluate and compare two parallel implementations of a simplified version (named SynQuake) of the popular game Quake. While in STM SynQuake support for maintaining consistency of each potentially complex game action is automatic, conservative locking of surrounding objects within a bounding-box for the duration of the game action is inherently needed in lock-based SynQuake. This leads to higher scalability of STM SynQuake versus lock-based SynQuake due to increased false sharing in the latter. Task assignment to threads has a second-order effect on scalability of STM-SynQuake, impacting the application's true sharing patterns. We show that a locality-aware task assignment provides the best trade-off between load balancing and conflict reduction.
98

Scalable and Transparent Parallelization of Multiplayer Games

Simion, Bogdan 15 February 2010 (has links)
In this thesis, we study parallelization of multiplayer games using software Transactional Memory (STM) support. We show that STM provides not only ease of programming, but also better scalability than achievable with state-of-the-art lock-based programming for this realistic high impact application. We evaluate and compare two parallel implementations of a simplified version (named SynQuake) of the popular game Quake. While in STM SynQuake support for maintaining consistency of each potentially complex game action is automatic, conservative locking of surrounding objects within a bounding-box for the duration of the game action is inherently needed in lock-based SynQuake. This leads to higher scalability of STM SynQuake versus lock-based SynQuake due to increased false sharing in the latter. Task assignment to threads has a second-order effect on scalability of STM-SynQuake, impacting the application's true sharing patterns. We show that a locality-aware task assignment provides the best trade-off between load balancing and conflict reduction.
99

A Study on the Brand Identity and Customer Loyalty- iPhone as an Example

Chu, Ting-Wei 06 October 2011 (has links)
In the recent years, the mobile phone from analog era to the 2G era and more to 3G, mobile phones is not only a single kind of communication products, but also it became an integral part in daily life. Advances in hardware and the popularity of telecommunications providers to provide 3G network service, makes smart phones became convenience and functional. It brings consumers a new experience. In June 2007, Apple led the launch of the iPhone. Its intuitive touch interface, multi-application software, and humanness designs, coupled with value-added services to mobile carrier model, and combined Internet community effect, creates a leading mobile company. Consumers still demand for the smart phones, and drive to the multi-function in the compound-oriented. Thus, a powerful portable devices become a must need. However, in varied mobile phone manufacturers, the most representative product is iPhone. In order to understand the niche market, we have to study the customer loyalty. And, we create literature related subject and conceptual framework for the iPhone users. In the study, the main structures are how customer satisfaction, brand identity and customer lock-in affect the customer loyalty. And, we will discover the co-related factors of the main frame. However, the point of view for the iPhone user will be also considered if the customer satisfaction (affection) will influence in customer loyalty. The affection factors will be considered as perceived usefulness, ease of use, compatibility and enjoyment. Last, w will reveal the analysis result and implication management.
100

Circuit Optimization Using Efficient Parallel Pattern Search

Narasimhan, Srinath S. 2010 May 1900 (has links)
Circuit optimization is extremely important in order to design today's high performance integrated circuits. As systems become more and more complex, traditional optimization techniques are no longer viable due to the complex and simulation intensive nature of the optimization problem. Two examples of such problems include clock mesh skew reduction and optimization of large analog systems, for example Phase locked loops. Mesh-based clock distribution has been employed in many high-performance microprocessor designs due to its favorable properties such as low clock skew and robustness. However, such clock distributions can become quite complex and may consist of hundreds of nonlinear drivers strongly coupled via a large passive network. While the simulation of clock meshes is already very time consuming, tuning such networks under tight performance constraints is an even daunting task. Same is the case with the phase locked loop. Being composed of multiple individual analog blocks, it is an extremely challenging task to optimize the entire system considering all block level trade-offs. In this work, we address these two challenging optimization problems i.e.; clock mesh skew optimization and PLL locking time reduction. The expensive objective function evaluations and difficulty in getting explicit sensitivity information make these problems intractable to standard optimization methods. We propose to explore the recently developed asynchronous parallel pattern search (APPS) method for efficient driver size tuning. While being a search-based method, APPS not only provides the desirable derivative-free optimization capability, but also is amenable to parallelization and possesses appealing theoretically rigorous convergence properties. In this work it is shown how such a method can lead to powerful parallel optimization of these complex problems with significant runtime and quality advantages over the traditional sequential quadratic programming (SQP) method. It is also shown how design-specific properties and speeding-up techniques can be exploited to make the optimization even more efficient while maintaining the convergence of APPS in a practical sense. In addition, the optimization technique is further enhanced by introducing the feature to handle non-linear constraints through the use of penalty functions. The enhanced method is used for optimizing phase locked loops at the system level.

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