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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.
231

THREE-DIMENSIONAL QUANTITATIVE ANALYSIS OF THE TRAJECTORY OF THE FOOT WHILE RUNNING

Cunningham, Thomas J. 01 January 2007 (has links)
Exercising the leg in a manner similar to running is theorized to have the potential effect of increasing performance and reducing occurrence of injuries in running athletes. Development of an exercise device that can help facilitate this method of specificity training could be beneficial to the sports community and should be investigated. Understanding the trajectory of the foot during the running gait is primary to further pursue this concept. 26 running athletes of varying characteristics participated in this study. Each subjects sex, age, weight, height, leg length, activity level and participation amount in their respective sport was recorded. Retro-reflective cameras captured the three-dimensional trajectory of each subjects right leg while running at speeds of 2, 3.8, 4.52 and 5.36 m/s for 10-15 seconds on a treadmill, respectively. The range of foot movement in each cardinal plane was determined for each speed. An ANCOVA revealed that leg length was the most determinate factor in trajectory range differences among subjects. Subjects were subsequently divided into quartiles based on leg length where further analysis revealed that foot displacement increased vertically and horizontally in the sagittal plane with increases in speed while trajectory in the third plane remained constant and substantially less in magnitude.
232

Transport and optical properties of semiconductor microstructures

Boero, Mauro January 1996 (has links)
No description available.
233

Transition metal oxofluorides comprising lone pair elements : Synthesis and Characterization

Hu, Shichao January 2014 (has links)
Within the family of transition metal oxochlorides/bromides containing lone pair elements, the transition metal cations often adopt a low-dimensional arrangement such as 2D layers, 1D chains or 0D clusters. The reduced dimensionality is attributed to the presence of stereochemically active lone pairs which are positioned in the non-bonding orbital and will not participate in bond formation and instead act as structural spacers that help to separate coordination polyhedra around transition metal cations from forming three dimensional networks. On the other hand, the chlorine and bromine ions also play an important role to open up the crystal structure because of their low coordination number. However, fluorine has been rarely used in this concept due to the difficulties in synthesis. This thesis is focused on finding new compounds in the M-L-O-F system (M = transition metal cation, L= p-block lone pair elements such as Te4+, Se4+, or Sb3+) in order to study the structural character of fluorine. Hydrothermal reactions have been adopted instead of conventional chemical transport reactions that are commonly used for synthesizing compounds in the M-L-O-(Cl, Br) family. A total of 8 new transition metal oxofluorides containing lone pair elements have been synthesized and their structures have been determined via single crystal X-ray diffraction. Bond valence sum calculations are used to distinguish in between fluorine and oxygen due to their very similar X-ray scattering factors. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>
234

Versus Associations : The familiarity between different influences. Patched together.

Ida, Pettersson January 2014 (has links)
In this text I am investigating the relationship between craft, fine art and kitsch/popular culture through the making of a three-dimensional pattern in patchwork technique. I apply the investigation to my working technique by comparing certain examples of fine art pieces with kitsch items. A method that during the process was named Versus Associations. I have connected the art pieces and kitsch items through this method of associations based on their similarities in colors and composition. The aim of the pattern is to mediate color interactions that make up a visual illusion. I want to make the beholders curious of what is happening in the pattern and show that it can affect them physically. / <p>Due to copyright some pictures has been removed. Numbers, representing these pictures, with attached web links can be found in references.</p>
235

Transverse flux machines for high torque applications

Maddison, Christopher Paul January 1999 (has links)
Transverse Flux Machines (TFM) present some interesting problems to the machine designer, electro-magnetically and mechanically. They offer the lure of an extremely high specific output, but only, apparently, at the price of intricate three dimensional flux paths, a complicated construction and a low power factor. The research covered by this thesis was concerned with the study, development and improvement of these machines with a view to reducing the detracting aspects of the marque whilst accentuating its advantages. Extensive three dimensional finite element analysis into a wide range of TFM topologies, was coupled with practical investigations into three prototype TFMs constructed at Newcastle University. The result of this work was an improved TFM topology with comparatively good power factor, a simple single sided geometry and a very high specific output.
236

Development of a Single-Stage Modulator for Comprehensive Two-Dimensional Gas Chromatography (GC × GC)

McNeish, Christopher January 2011 (has links)
The ability to effectively analyze particulate matter (PM2.5) in air is becoming increasingly pertinent. Allen Goldstein of the University of California in Berkeley is studying the semi-volatile fraction of organic compounds in PM2.5 through the use of the thermal desorption aerosol gas chromatograph (TAG) system. However, as conventional GC does not provide adequate separation power, the development of comprehensive two-dimensional gas chromatography (GC × GC) was required. GC × GC works more effectively by utilizing a modulator that periodically traps and focuses analytes from a primary column onto a secondary column. This allows for the primary and secondary columns to separate the analytes based on two different properties. This report focuses on the continuing study and enhancement of a modulator designed by Ognjen Panić during his Masters project. Improving and testing the robustness of this dual stage modulator was originally the focus of this project. However, this study led to the development of a single stage modulator. In addition to that, the effect of modulator characteristics such as length of the restriction, total length of the modulator and wall thickness on the modulator performance were studied. A robustness test of the single stage modulator was also completed. Experiments conducted tested the characteristics of the new modulator to ensure it performed effectively and would satisfy the requirements of the TAG system. A study comparing the sensitivity of conventional gas chromatography and GC × GC was also preformed. The sensitivity of GC × GC was on average an order of magnitude better than that of 1D GC.
237

Stochastic heat equations with memory in infinite dimensional spaces

Xie, Shuguang, School of Mathematics, UNSW January 2005 (has links)
This thesis is concerned with stochastic heat equation with memory and nonlinear energy supply. The main motivation to study such systems comes from Thermodynamics, see [85]. The main objective of this work is to study the existence and uniqueness of solutions to such equations and to investigate some fundamental properties of solutions like continuous dependence on initial conditions. In our approach we follow the seminal papers by Da Prato and Clement [10], where the stochastic heat equation with memory is tranformed into an integral equation in a function space and the so-called mild solutions are studied. In the aforementioned papers only linear equations with additive noise were investigated. The main contribution of this work is the extension of this approach to nonlinear equations. Our main tools are the theory of stochastic convolutions as developed in [33] and the theory of resolvent kernels for deterministic linear heat equations with memory, see[10]. Since the solution at time t depends on the whole history of the process up to time t, the resolvent kernel does not define a semigroup of operators in the state space of the process and therefore a ???standard??? theory of stochastic evolution equations as presented in the monograph [33] does not apply. A more delicate analysis of the resolvent kernles and the associated stochastic convolutions is needed. We will describe now content of this thesis in more detail. Introductory Chapters 1 and 2 collect some basic and essentially well known facts about the Wiener process, stochastic integrals, stochastic convolutions and integral kernels. However, some results in Chapter 2 dealing with stochastic convolution with respect to non-homogenous Wiener process are extensions of the existing theory. The main results of this thesis are presented in Chapters 3 and 4. In Chapter 3 we prove the existence and uniqueness of solutions to heat equations with additive noise and either Lipschitz or dissipative nonlinearities. In both cases we prove the continuous dependence of solutions on initial conditions. In Chapter 4 we prove the existence and uniqueness of solutions and continuous dependence on initial conditions for equations with multiplicative noise. The diffusion coefficients defined by unbounded operators are allowed.
238

An Investigation of the Dimensional Stability of Dental Alginates

Nichols, Paul Vincent January 2006 (has links)
Master of Science (Dentistry) / Dimensional stability was defined by Nicholls (1977) as “the ability (of a material) to maintain accuracy over time”, and the result of loss of accuracy, “distortion”, as “the relative movement of a single point, or group of points, away from some originally specified reference position such that permanent deformation is apparent”. Maintaining dimensional stability of dental impression materials is vital if the impression cannot be cast (in stone) soon after removal from the mouth. Dental irreversible hydrocolloid (alginate) is a major dental impression material used worldwide in many clinical procedures. However, alginate is dimensionally unstable and changes its dimensions (suffers “distortion”) after removal from the mouth. With storage times of more than ten minutes, alginate begins to distort, and after one to three hours (depending on the product and storage conditions) cannot be used for many clinical purposes, especially fixed prosthodontics such as crowns and bridges (Hampson 1955, Skinner & Hoblit 1956, Wilson & Smith 1963, Rudd et al. 1969, Miller 1975, Inohara 1977, Schoen et al. 1978, Coleman et al. 1979, Linke et al. 1985, Habu et al. 1986, Peutfeldt & Asmussen 1989, Mathilde & Peters 1992, Khan & Aziz Sahu 1995, Eriksson et al. 1998, Schleier et al. 2001, and Donovan & Chee 2004). This loss of accuracy, due to dimensional instability, manifests as a time-dependent distortion of the poured stone cast, and thus any prosthesis fabricated will not fit in the mouth. With the introduction of the more stable elastomers in the 1950s (Stackhouse 1970, Glenner 1997, Brown 2003) that could be stored for days if necessary, without loss of accuracy, the alginates fell out of favour for fixed prosthodontics. Recently, there has been a resurgence of interest in alginate for use in dental procedures where dimensional stability is critical (Peutzfeldt and Asmussen 1989, Eriksson et al. 1998). This in part is due to the favourable properties of alginate not found in the elastomers. Of greatest significance is that alginate hydrocolloid is hydrophilic, whereas elastomers are hydrophobic (Phillips & Ito 1958, Glenner 2004). Thus, alginate materials are able to reproduce wet oral areas with greater precision and to produce a superior "fit" of, say, a gold casting produced by the Lost Wax technique (Skinner and Phillips 1982). A number of reports have been published which investigate newer alginate materials that are claimed to be more dimensionally stable than older formulations. Puetzfeldt and Asmussen (1989) found that a newer alginate , if stored at 100% relative humidity, retained accuracy over 24 hours that was equivalent to that of the elastomers. More recently, the manufacturer of another alginate has claimed equivalent dimensional stability to the elastomers for up to 100 hours, and, whilst this claim has not been reported on in the literature, the present thesis will show that, under favourable conditions of storage, the material maintained clinically useful accuracy for up to 100 hours. Another approach to improving the accuracy of alginate impressions has been to combine reversible hydrocolloid with alginate (the “Bilaminar” technique). Frederick and Caputo (1997) confirmed that the new agar reversible hydrocolloids are just as accurate (at the time of removal from the mouth) as the new elastomers. Mathilde et al. (1992) and Eriksson et al. (1998) have shown that several of the “bilaminar” impression techniques for fixed prosthodontics, where alginate is used as a tray material supporting a reversible hydrocolloid (agar) wash, are as accurate and dimensionally stable as elastomers for up to three hours. However, these studies are difficult to interpret due to lack of uniformity in the testing methods, and the fact that there is no regulatory standard available to measure dimensional stability for dental alginates. The International Standard (IS) for alginate impression materials (ISO 1563:1990E) contains no specification for dimensional stability, and thus places no requirement for manufacturers to state dimensional stability properties on their labels. In contrast, ISO 4823:1992(E) specifies the IS for elastomeric dental impression materials, and it does specify a requirement for dimensional stability (less than 1.5% distortion after 24 hours). Further, the IS sets a method for determination of dimensional stability. Briefly, this method (the Optical Method) uses a travelling optical microscope to measure the accuracy of the distance between score lines on an impression of a test grid, at various time periods. The American Dental Association Specification No. 19 for dental elastomeric impression materials is identical to the IS. There is currently no specific Australian Standard (AS) for the dimensional stability of any dental impression material. Overview of Experimental Methods A. The Optical Method The aim of Part A of this investigation was to: 1. Adapt the Optical Method of the IS for elastomers to be reproducible for dental alginates. This was achieved by using a perforated test tray (to simulate clinical conditions), and measuring the grid pattern on a dental stone button after casting the test impression, rather than direct measurement of the impression, as for the IS. 2. To measure and rank the dimensional stability of a number of locally available dental alginates. Measurements of the test stone buttons proved reproducible, and the results were different for each sample, allowing them to be ranked according to dimensional stability after 50 and 100 hours of storage. The results show that the traditional optical method for measuring dimensional stability, as specified in the IS for dental elastomers, can be adapted to measure the dimensional stability of dental alginates However, the Optical Method of measuring dimensional stability of dental alginates is cumbersome and time-consuming. It was hypothesised that dimensional stability of dental alginates could be measured more conveniently by finding a thermal property that is directly proportional to dimensional stability. This method could be useful for the rapid determination of relative performance, and allow comparison with a determined benchmark. B. The Thermal Method Recently, modern methods of Thermal Analysis, Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) have been used to rapidly age various polymers, including food alginates (Chinachoti 1996), in order to measure thermal stability. This thesis shows that thermal stability is an indicator of dimensional stability. The aim of Part B of this investigation was therefore to adapt thermal analysis techniques to dental alginates, and develop a method to measure their thermal stability. These results were then compared with those for dimensional stability measured by the Optical Method to determine the relationship between thermal and dimensional stability for dental alginates. The results show that current thermal analysis methods of TGA and DSC can be adapted to measure relative dental alginate dimensional stability, and are both rapid and convenient. This study also provides evidence that commercial products differ as regards the property of dimensional stability, and can be ranked accordingly. C. Practical Application of the Methods The aim of part C of this thesis was to validate the methods (both optical and thermal) developed in this study by using them to investigate the effect of varying the water/powder ratio on the dimensional stability of dental alginates. It was shown that dimensional stability is affected by changes to the recommended water/powder ratio, that both the methods detected and measured the changes, and that the results were proportional, in that any percentage change detected by the optical method, was mirrored by the thermal method, confirming that the more convenient thermal methods can be used to measure dimensional stability.
239

Noncontact 3D biological shape measurement from multiple views

Ge, Youmei January 1994 (has links)
Many clinically important applications require measurements on a large portion of the human body surface that may not be visible from a single view. For example, a single view may be insufficient for the measurement of a complete facial surface for facial plastic surgery. And observing breast surfaces from multiple views is needed in accurate breast volume measurement. On the other hand most 3D vision systems only recover 3D data from a single viewpoint and the recovered 3D data are often incomplete due to the occlusion problem and thus cannot uniquely define the surface. A unique and more complete description of the surface is necessary for most applications such as measuring area or volume and finding the best 3D registration between corresponding surfaces. This thesis describes a structured light based system for fast and noncontact 3D measurement of the human body from multiple views. A particular application of our system is the study of human lactation through measuring the breast surface and volume. Fast, accurate, non-contact, and biologically safe measurement is the key requirement in our application. We use structured light to fulfill the requirement. Based on the SHAPE system [4,3], a single view structured light system developed at Monash University, our system for breast volume measurement generates more complete 3D information on object surfaces by observing the object from more than one viewpoint. The breast volume is computed using the integrated data from all views. We present a simple method that performs 3D measurement from multiple views simultaneously. Combined with a camera and a projector, a mirror is used in the method to create an additional viewpoint to recover the occluded regions that are illuminated by the light source but were previously invisible to the camera. Images from the two views one directly seen by the camera and the other seen via the mirror are taken simultaneously. We develop the method for the purpose of achieving more complete measurements without increasing image capture time, which is very useful in situations where both speed and accuracy are important. The complete 3D description of the surface of objects requires the acquisition of several images from different vantage viewpoints. Each image contains information on the part of the object that is visible from its viewpoint. A very important task consists in the integration of the information present in each view. We have developed a two view system to achieve a more complete breast volume measurement. The system uses a stationary sensor at each view. Our system can largely eliminate the occlusion regions produced by a single view system and all data from different views are integrated into an object centered coordinate system and resampled by a single parametric grid. The system has been used to accurately measure short term changes in breast volume for lactating mothers. Currently, the system is also used to observe the breast volume change of pregnant women over many weeks' time.
240

New interaction techniques for the digital library : 3D focus+context interactive visualization /

Shiaw, Horn-yeu. January 1900 (has links)
Thesis (Ph.D.)--Tufts University, 2003. / Adviser: Robert J. K. Jacob. Submitted to the Dept. of Computer Science. Includes bibliographical references (leaves 201-217). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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