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Characterizing Polymers for Cardiovascular DevicesWarren, Phillip Daniel January 2012 (has links)
Abdominal aortic aneurysm (AAA) occurs in developed nations. The current treatment, endovascular aneurysm repair (EVAR), while successful, has shortcomings. A solution to the concerns with EVAR is a polymeric endo-aortic paving (PEAP). Our goal is to further develop this treatment for AAA. We hypothesize that PEAP will overcome the current limitations associated with current AAA repair, while maintaining the desirable qualities of these materials are biocompatibility, thermoformability, and material compliance with aortic tissue. The purpose of this work was to evaluate potential PEAP material candidates, which include acrylate-based shape memory polymers (SMPs), polycaprolactone (PCL) and polyurethane (PU) blends, and finally a PCL-based bioresorbable copolymer poly (ester-urethane-urea) (PEUU). Materials were assessed by characterization of their chemical, thermomechanical and degradation properties. It was determined that acrylate- SMPs were too stiff to be candidates for use in PEAP. The control of the PEUU copolymer composition yielded a material that had increased degradability while maintaining valuable characteristics of the PCL/PU blend prior to, during, and following degradation. The difference between the PU hydrophobicity dictated MTM sensitivity to water immersion and degradation characteristics. Conventional statistics were used to develop three models for predicting key properties of PEUU. Important variables, such as PCL M(n), temperature, and crystallinity were found to impact both copolymer microstructure and mechanical properties.
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Investigation of the performance of microstrip gas detectors for X-rays and evaluation of their application to mammographyPaganestis, Antonios January 1997 (has links)
No description available.
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Development of a visualisation environment to aid the evaluation of finger joint prosthesesPenrose, Justin M. T. January 2001 (has links)
No description available.
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Application of ultrafast lasers to photorefractive holography through turbid mediaJones, Richard January 1998 (has links)
No description available.
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An investigation into gallium arsenide liquid crystal light valvesHebbron, Michael Christopher January 1996 (has links)
No description available.
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Effective development of haptic devices using a model-based and simulation-driven design approachAhmad, Aftab January 2014 (has links)
Virtual reality (VR)-based surgical simulators using haptic devices can increase the effectiveness of surgical training for surgeons when performing surgical procedures in hard tissues such as bones or teeth milling. The realism of virtual surgery through a surgical simulator depends largely on the precision and reliability of the haptic device, which reflects the interaction with the virtual model. The quality of perceptiveness (sensation, force/torque) depends on the design of the haptic device, which presents a complex design space due to its multi-criteria and conflicting character of functional and performance requirements. These requirements include high stiffness, large workspace, high manipulability, small inertia, low friction, high transparency, and cost constraints. This thesis proposes a design methodology to improve the realism of force/torque feedback from the VR-based surgical simulator while fulfilling end-user requirements. The main contributions of this thesis are: 1. The development of a model-based and simulation-driven design methodology, where one starts from an abstract, top-level model that is extended via stepwise refinements and design space exploration into a detailed and integrated systems model that can be physically realized. 2. A methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device, which considers the stiffness of actuation systems, flexible links and passive joints. 3. A robust design optimization approach to find the optimal numerical values for a set of design parameters to maximize the kinematic, dynamic and kinetostatic performances of a 6-degrees of freedom (DOF) haptic device, while minimizing its sensitivity to variations in manufacturing tolerances and cost, and also satisfying the allowed variations in the performance indices. 4. A cost-effective approach for force/torque feedback control using force/torque estimated through a recursive least squares estimation. 5. A model-based control strategy to increase transparency and fidelity of force/torque feedback from the device by compensating for the natural dynamics of the device, friction in joints, gravity of platform, and elastic deformations. / <p>QC 20140415</p>
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A New Approach to Telemetry Data Decomposition and Analysis Based on Large-Capacity Semiconductor RAMJun, Zhang, Qishan, Zhang, Zhihui, Zhang, Jian, Huang 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / With the development of microelectronics and computer technology, telemetry computer systems are demanded to provide larger storage capacity and higher storage data rate than ever before. This paper fully considers various factors of a high-speed PCM fiber-optic telemetry system such as data format, data rate, data storage, the width of data storage, storage data rate. All these considerations lead to a new scheme with a semiconductor RAM and a dedicated program as its basic idea. This scheme chooses 1Mbits or 4Mbits static-RAM chips to implement the telemetry data storage device with a total capacity of 4Mbytes, 16Mbytes, or 64Mbytes. The software running on COMPAQ 386/25M or its compatibles is written in Turbo C 2. 0 to fetch, decompose, display and process data stored in the large-capacity RAM. The main task of the system processing software is to identify the flag words of frame sync-code -pattern and then demultiplex the data into separate channel data to be stored in the disk. Besides the ability to recognize specific data format, the software can also rectify data confusion to some extent. The scheme has already been proved to be efficient to receive large capacity of data with features of high data rate, high data storage in a short time.
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A syllabus for an undergraduate course in polymer chemistry: the classroom testing of this deviceOkoh, Fred I. 01 July 1985 (has links)
No description available.
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Radiation damage in charge coupled devicesSmith, David Ryan January 2003 (has links)
This thesis is concerned with the effects of radiation damage in CCDs used for space applications. The manufacturing process and operational principles of CCDs are presented in Chapter 2. The components of the space radiation environment, the two radiation damage mechanisms relevant to CCDs, and the effects of radiation on the operational characteristics of CCDs are described in Chapter 3. Chapter 4 presents a study to assess the suitability of novel L3Vision technology to applications in space. Two L3Vision CCDs were subjected to proton irradiations representative of doses expected to be received by spacecraft in low Earth orbit. Post-irradiation the devices were found to operate as expected, the effects of radiation on the operational characteristics of the devices being comparable to previous studies. The effect of low energy protons on CCDs is the subject of Chapter 5. The study was initiated in response to the finding that soft protons could be focused by the mirror modules of the XMM-Newton spacecraft onto the EPIC CCD detectors. Two EPIC devices were irradiated with protons of a few keV to find that soft protons cause more damage than that expected by the NIEL damage relationship, as they deposit most of their energy within the CCD. The observed change in CTI of the EPIC devices on XMM-Newton is however comparable to the pre-launch prediction, and the component attributable to low energy protons is small, < 20%. Chapter 6 presents a study of a specific radiation induced phenomenon, `Random Telegraph Signals'. Development of analysis software and the irradiation of two CCDs are discussed before a detailed characterisation of the generated RTS pixels is presented. The study shows that the mechanism behind RTS involves a bi-stable defect linked with the E-centre, in combination with the high field regions of a CCD pixel.
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Deep Muscle Relaxation Obtained with Analog Electromyographic Information FeedbackBates, Charles Edward 05 1900 (has links)
The purpose of the research study was to provide improved relaxation training with the use of an electromyography feedback device based on the design of Green et al. (1969). It was intended that this instrument would allow the training of deep muscle relaxation to the point of neuro-muscular silence, while remaining inexpensive enough to be applied in the clinical setting.
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