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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.
301

Surface modification of NiTi for long term orthopedic applications

Chan, Yee-loi., 陳以來. January 2007 (has links)
published_or_final_version / abstract / Orthopaedics and Traumatology / Master / Master of Philosophy
302

Dynamic Tactile Information is Sufficient for Precise Curvature Discrimination

Cheeseman, Jacob R. 01 July 2015 (has links)
Our tactile perceptual experiences occur when we interact, actively and passively, with environmental objects and surfaces. Previous research has demonstrated that active manual exploration enhances the tactile perception of object shape. Nevertheless, the factors that contribute to this enhancement are not well understood. The present study evaluated the ability of 14 older adults to discriminate curved surfaces by actively feeling objects with a single index finger and by passively feeling objects that moved relative to a restrained finger. The curvature discrimination thresholds obtained for passive-dynamic touch were significantly lower than those that occurred during active-dynamic touch. This result demonstrates that active exploratory movements of the hand and fingers do not necessarily lead to the best curvature discrimination performance; rather, performance was best in the current study when dynamic tactile stimulation occurred in the absence of active movement. The results of the present study also clarify those obtained by Norman et al. (2013), who found that active-dynamic touch was superior to static touch -- the current findings extend this previous research and indicate that passive-dynamic touch can yield performance that is even higher than what is obtained for active-dynamic touch.
303

Constrained, non-linear, derivative-free parallel optimization of continuous, high computing load, noisy objective functions.

Vanden Berghen, Frank 28 June 2004 (has links)
The main result is a new original algorithm: CONDOR ("COnstrained, Non-linear, Direct, parallel Optimization using trust Region method for high-computing load, noisy functions"). The aim of this algorithm is to find the minimum x* of an objective function F(x) (x is a vector whose dimension is between 1 and 150) using the least number of function evaluations of F(x). It is assumed that the dominant computing cost of the optimization process is the time needed to evaluate the objective function F(x) (One evaluation can range from 2 minutes to 2 days). The algorithm will try to minimize the number of evaluations of F(x), at the cost of a huge amount of routine work. CONDOR is a derivate-free optimization tool (i.e., the derivatives of F(x) are not required. The only information needed about the objective function is a simple method (written in Fortran, C++,...) or a program (a Unix, Windows, Solaris,... executable) which can evaluate the objective function F(x) at a given point x. The algorithm has been specially developed to be very robust against noise inside the evaluation of the objective function F(x). This hypotheses are very general, the algorithm can thus be applied on a vast number of situations. CONDOR is able to use several CPU's in a cluster of computers. Different computer architectures can be mixed together and used simultaneously to deliver a huge computing power. The optimizer will make simultaneous evaluations of the objective function F(x) on the available CPU's to speed up the optimization process. The experimental results are very encouraging and validate the quality of the approach: CONDOR outperforms many commercial, high-end optimizer and it might be the fastest optimizer in its category (fastest in terms of number of function evaluations). When several CPU's are used, the performances of CONDOR are currently unmatched (may 2004). CONDOR has been used during the METHOD project to optimize the shape of the blades inside a Centrifugal Compressor (METHOD stands for Achievement Of Maximum Efficiency For Process Centrifugal Compressors THrough New Techniques Of Design). In this project, the objective function is based on a 3D-CFD (computation fluid dynamic) code which simulates the flow of the gas inside the compressor.
304

An Investigation of Backgrounds in the DEAP-3600 Dark Matter Direct Detection Experiment

Veloce, LAURELLE 11 October 2013 (has links)
Astronomical and cosmological observations reveal that the majority of the matter in our universe is made of an unknown, non-luminous substance called dark matter. Many experimental attempts are underway to directly detect particle dark matter, which is very difficult to measure due to the expected low interaction rate with normal matter. DEAP-3600 is a direct dark matter search experiment located two kilometres underground at SNOLAB, in Sudbury, Ontario. DEAP-3600 will make use of liquid argon as the detector material, which scintillates as charged particles pass through. The work presented here is an investigation of expected background sources in the DEAP detector. Because DEAP-3600 is a noble liquid-based experiment, a thin film of [1,1,4,4]-tetraphenyl-[1,3]-butadiene (TPB) is coated on the detector walls to shift the scintillation peak from the UV to visible regime for detection. However, alphas passing through TPB produce scintillation signals which can mimic recoil events. Because scintillation properties can change with temperature, we have conducted an investigation of alpha-induced TPB scintillation at temperatures ranging from 300 K to 3.4 K. We were able to characterize the light yield and decay times, and demonstrated that these background events should be distinguishable from true recoil events in liquid argon, thus enabling DEAP-3600 to achieve higher dark matter sensitivity. Additionally, we investigate the performance of the liquid argon purification systems, specifically the activated charcoal used for radon filtration. Previous measurements with the DEAP prototype experiment have demonstrated the necessity of removing radon from the argon prior to filling the detector, due to the release of contaminates from the argon storage systems. Charcoal radon filters are extremely efficient, however, if the emanation rate of the charcoal is too high, there is the possibility of re-contamination. We performed a measurement of the radon emanation rate of a charcoal sample using a radon emanation and extraction system at Queens University. We demonstrated that the emanation rate of the charcoal was consistent with zero. We also show that the number of residual radon atoms which reach the detector would not be an issue for DEAP-3600. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-10-10 18:36:40.2
305

Processing of NITI reinforced adaptive solder for electronic packaging / Processing of nickel titanium reinforced adaptive solder for electronic packaging

Wright, William L. 03 1900 (has links)
Approved for public release; distribution is unlimited / Solder joints provide both electrical and mechanical interconnections between a silicon chip and the packaging substrate in an electronic application. The thermomechanical cycling (TMC) in the solder due to the mismatch of the coefficient of thermal expansion (CTE) between the silicon chip and the substrate causes numerous reliability challenges. This situation is aggravated by the ongoing transition to lead-free solders worldwide, and the trend towards larger, hotter-running chips. Therefore, improved solder joints, with higher resistance to creep and low-cycle fatigue, are necessary for future generations of microelectronics. This study reports in the development a process to fabricate solder joints with a fine distribution of shape memory alloys (SMA) NiTi particulates. The microstructure and interface zone of the as-reflowed solder-SMA composite has been characterized. / Lieutenant, United States Navy
306

Project SHAPE (Students Helping Advocate for Patient Education)

Calabro, Kristin, Shields, Whitney January 2010 (has links)
Class of 2010 Abstract / OBJECTIVES: The purpose of Project SHAPE was to provide an interdisciplinary workshop for future practitioners from the Colleges of Pharmacy, Medicine and Public Health on health literacy to improve the communication between the patients and their providers. METHODS: Study participants were recruited via email from the Colleges of Pharmacy, Medicine, and Public Health at The University of Arizona. Participants attended a workshop that included a one-hour presentation by Dr. Barry Weiss followed by the development of educational materials on various health topics. A retrospective analysis of the health professional students’ knowledge of health literacy was performed. Materials were provided to El Rio Community Health Center, Colleges of Pharmacy, Medicine and Public Health to distribute to their patients in the Tucson community. RESULTS: Students’ overall knowledge on health literacy and communication with patients improved by 88% after the presentation. A total of nine different low literacy educational materials were developed by the students who attended the workshop. Copies of the educational materials were given to participating students from the other colleges to use in their patient outreach programs. The materials were also distributed to patients at a variety of brown bags, community health fairs, screenings, and El Rio Community Health Center. CONCLUSIONS: Project SHAPE has already affected many future healthcare practitioners through the interdisciplinary workshop. The educational materials will continue to be provided to patients in the Tucson community.
307

Thermal Shape Factor : The impact of the building shape and thermal properties on the heating energy demand in Swedish climates

Olsson, Martin January 2016 (has links)
In the year 2006, the energy performance directive 2002/91/EG was passed by the European Union, according to this directive the Swedish building code was supplemented by a key measure of energy use intensity (EUI). The implemented EUI equals some energy use within a building divided by its floor area and must be calculated in new housing estate and shown when renting or selling housing property. In order to improve the EUI, energy efficiency refurbishments could be implemented. Building energy simulation tools enables a virtual view a building model and can estimate the energy use before implementing any refurbishments. They are a powerful resource when determine the impact of the refurbishment measure. In order to obtain a correct model which corresponds to the actual energy use, some adjustments of the model are often needed. This process refers to as calibration. The used EUI has been criticized and thus, the first objective in this work was to suggest an alternative key measure of a buildings performance. The results showed that the currently used EUI is disfavoring some districts in Sweden. New housing estate in the far north must take more refined actions in order to fulfill the regulation demand, given that the users are behaving identical regardless where the house is located. Further, the suggested measure is less sensitive to the users’ behavior than the presently used EUI. It also has a significance meaning in building design as it relating the building shape and thermal properties and stating that extreme building shapes must undergo a stricter thermal construction rather than buildings that are more compact. Thus, the suggested key measure also creates a communication link between architects and the consultant constructors. The second objective of this thesis has been to investigate a concept of calibration using the data normally provided by energy bills, i.e. some monthly aggregated data. A case study serves to answer this objective, by using the building energy simulation tool IDA ICE 4.7 and a building located in Umeå, Sweden. The findings showed that the used calibration approach yielded a model considered as calibrated in eleven of twelve months. Furthermore, the method gives a closer agreement to the actual heat demand rather than using templates and standardized values. The major explanation of the deviation was influence of the users, but also that the case study building burden with large heat losses by domestic hot water circulation and thus, more buildings should be subjected to this calibration approach.
308

Sculptural Textiles : Exploring sculptural possibilities in woven textiles through construction and contrasting yarns.

Jazayeri, Statira January 2016 (has links)
Sculptural Textiles is a material investigation exploring sculptural possibilities for machine woven textiles. Two important factors are yarn combinations and textile construction, and how these two together can result in fabrics that can be manipulated by hand into shapes and thus adaptable to various settings. The essence of this project is in the meeting between contrasts such as shiny-dull, elastic-stiff, transparent-opaque, natural and synthetic and how these meetings can create sculptural qualities. The project is aiming to create a range of sculptural textiles as well as being an exploration in material. Construction and density are tools to bring forth the beauty and function of the materials. The result is a range of textiles showing that small changes in material and construction can lead to different sculptural characteristics.
309

Matematické modelování magnetosriktních látek / Matematické modelování magnetosriktních látek

Vermach, Lukáš January 2011 (has links)
4 Title: Mathematical modeling of magnetostrictive materials Author: Lukáš Vermach Department: Mathematical Institute of Charles University Advisor: Priv.-Doz. Dr. habil. RNDr. Martin Kružík Ph.D., Institute of Information Theory and Automation, Academy of Sciences of the Czech Republic Advisor's e-mail address: kruzik@utia.cas.cz Abstract In the present work we introduce an isotermic mathematical model of ferromagnetic shape memory alloys (FSMAs). FSMAs are a special class of magnetostrictive materials, i.e. materials which deform their shape on account of external magnetic field or which change magnetization as a consequence of strain. This property originates from phase transformations that occur within the material when being exposed to external loading. First, the stationary model of FSMA is formulated. The thermodynamical potential is composed (Helmholz free energy) and its non-quasiconvexity is discussed. The quasicon- vexification is performed via the relaxation theory, i.e. quasiconvex envelope construction. For such a model the existence theory is built. Then, taking advantage of the stationary case the evolutionary model is developed. The attention is drawn to hysteresis, which arises from energy dissipation. The time discretization leads to a sequence of hysteresis-modified stationary problems (the...
310

Optimalizace potrubních tvarovek / Optimization of an adapting pipes

Svozil, Jan January 2012 (has links)
Adapting pipes are a significant part of any pipe-line network and they are the sources of substantial hydraulic losses. They are designed for a manufacturing simplicity, regardless of flow. This paper concerns with lowering of hydraulic losses of adapting pipes by means of the shape optimization. Several methods of a mathematical optimization are tested and due to the complexity of the task and the need of the computational distribution among several computers, the gradient based algorithm is used. These methods loop together with a CFD software then automatically explore the design space. Several optimizations of diffusers with different opening angles, shape parameterizations and boundary conditions are made for the better insight on hydraulic losses. In three chapters there is description of development of parametric description of bend by means of Bezier surfaces. At the end optimum shape is found with hydraulic losses were decreased about 22%, which was not validated by experiment. In the final chapter is application of developed software on the shape optimization of Kaplan draft tube.

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