This thesis is concerned with a mathematical study of several problems involving infiltration from irrigation channels into an unsaturated homogeneous soil. All the problems considered are two dimensional and are solved numerically by employing boundary integral equation techniques. In the first chapter I introduce some of the literature and ideas surrounding my thesis. Some background information is stated followed by an outline of the thesis and a list of author’s published works that support the material in the thesis. Full descriptions of the fundamental equations used throughout the thesis are provided in chapter 2. Chapter 3 contains the first problem considered in this thesis which is infiltration from various shapes of single and periodic irrigation channels. Specifically strip, semi-circular, rectangular and v shaped channels. The solutions are obtained using the boundary element technique. The solutions are then compared with the results obtained by Batu [14] for single and periodic strip sources. In chapter 4 a boundary integral equation method is adopted for the solution of flow from single and periodic semi-circular channels into a soil containing impermeable inclusions. The impermeable inclusions considered are of rectangular, circular and square shapes. The aim is to observe how the various shapes of inclusions can affect the direction of the flow particularly in the region adjacent to the zone where plant roots would be located. Chapter 5 solves the problem of infiltration from single and periodic semicircular irrigation channels into a soil containing impermeable layers. A modification is made to the boundary integral equation in order to include the impermeable layers with the integration over the layers involving Hadamard finite-part integrals. The objective of the work is to investigate how the number and the depth of the impermeable layers affects the flow. Chapter 6 employs a particular Green’s function in the boundary integral equation. The Green’s function is useful for flow from a single channel since it removes the need to evaluate the boundary integral along the soil surface outside the irrigation channel. A time dependent infiltration problem is considered in chapter 7. The Laplace transform is applied to the governing equations and the boundary integral equation technique is used to solve the resulting partial differential equation. The Laplace transform is then inverted numerically to obtain the time dependent values of the matric flux potential. / Thesis (Ph.D.) - University of Adelaide, School of Mathematical Sciences, 2008

"February 2003" / Bibliography: p. 121-135. / xii, 135 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis is a theoretical evaluation of the (single) first photon detection (FPD) technique as a limiting case of time-resolved transillumination (TI) for diagnostic purposes. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 2003

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

<p>To get the maximal output of your exercise in gym machines, there are different factors</p><p>to be considered. For example the strength of the muscle varies dependent on the position</p><p>of the muscles. To get the best results of the exercise the load has to reduce and increase</p><p>at specific positions.</p><p>This study was made in cooperation with Caretaker Scandinavia AB, a company for</p><p>sales, marketing and development in health care. They are general agent for Nordic Gym</p><p>who works with manufacturing of equipment and machines for gym and fitness.</p><p>The aim of this study was to generate a method of measurement to evaluate and control</p><p>the biomechanics of Nordic Gym´s workout equipment. A protocol for an ergonomic</p><p>analysis on the equipment has also been elaborated.</p><p>One of the methods to measure the biomechanics was to measure the torque through the</p><p>whole movement. The other method was electromyography (EMG). The EMGequipment</p><p>registers electric signals that are generated in a working muscle, and makes it</p><p>possible to see when the maximum muscle activity achieves. The results of those</p><p>measurements will be compared to the muscles strengthprofile which describes how the</p><p>muscle generates power in different positions throughout the movement.</p><p>To measure the ergonomics an ergonomic protocol where produced, which was based on</p><p>ergonomics aspect, adapted to gym machines.</p><p>The method of measurement where tested on Nordic Gym´s training machine 101SE leg</p><p>extension and Free Motion´s machine Leg Extension GZF18013 and this machines where</p><p>controlled and evaluated. Two test persons tried out the machines and the machines</p><p>where analysed in an ergonomic and a biomechanical perspective. The result shows that</p><p>the biomechanics of Nordic Gym´s machine where a bit better than the biomechanics of</p><p>FreeMotion´s machine. But in the both case the difference between the values of torque is</p><p>marginal, to improve the biomechanics insistence a bigger different should be necessary</p><p>to use. The ergonomic analyse of the machines showed that the ergonomics where good</p><p>and well planed. Both machines had some small ergonomic lacks, which can be</p><p>improved.</p>

Seismic refraction measurements along two unreversed lines indicate that the earth's crust is 26 km thick in southeastern Alaska and 30 km thick along the Inside Passage of British Columbia. The crust in southeastern Alaska, north of Dixon Entrance, consists of a layer 9 km thick with a seismic velocity of 5.90 km/sec, a layer 7 km thick with a seismic velocity of 6.30 km/sec. and a layer 10 km thick with a seismic velocity of 6.96 km/sec. The crust along the Inside Passage of British Columbia, south of Dixon Entrance, consists of a layer 13 km thick with a seismic velocity of 6.03 km/sec, a layer 5 km thick with a seismic velocity of 6.41 km/sec, and a layer 12 km thick with a seismic velocity of 6.70 km/sec. The velocity of the mantle below the M discontinuity is 7.86 km/sec in southeastern Alaska and 8.11 km/sec in British Columbia. A compilation of Bouguer gravity data along the Inside Passage from northern Vancouver Island to northern southeastern Alaska indicates near-zero anomalies between steep gradients offshore and near the western margin of the Coast Mountains. A two-dimensional gravity model, constrained by seismic refraction measurements, suggests that the thickness of the crust is constant beneath the region of near-zero gravity anomalies and indicates a step-like transition between oceanic and continental structure. Seismic reflection, gravity, and magnetic measurements, obtained during a 1970 cruise of the R/V Yaquina, help to determine upper crustal structures in Dixon Entrance. Gravity models, constructed to agree with these data and the measurements of previous investigators, indicate sediment thicknesses of nearly 3 km east of Learmonth Bank and west of Celestial Reef. Magnetic models suggest large lateral changes in basement susceptibility. Either highly metamorphosed rock or basaltic intrusions can account for these changes in susceptibility. Folded sediments suggest post depositional distortion due either to regional compression or to major local intrusions. Several linear gravity features, observed in northern Dixon Entrance, disappear north of Graham Island. Either the structures responsible for the gravity features end or thick layers of basalt, extending northward from Graham Island, obscure the effect of the structures. A single-station survey detected microearthquakes at nine locations in western British Columbia and southeastern Alaska. The majority of the observed distant microearthquakes probably originated in the Queen Charlotte Islands fault zone. However, observed nearby microearthquakes indicate a microearthquake seismicity of several events per day along the mainland coast of British Columbia. Temporary seismic arrays located at a site along the central portion of Chatham Strait near the Chatham Strait fault and at a site in Glacier Bay recorded few nearby microearthquakes. Arrivals at the arrays permitted the location of distant microearthquakes, however, with epicenters in the vicinity of northern Lynn Canal and along the Fairweather fault. / Graduation date: 1972

AMANDA-II est un télescope à neutrinos composé d'un réseau tri-dimensionnel de senseurs optiques déployé dans la glace du Pôle Sud. Son principe de détection repose sur la mise en évidence de particules secondaires chargées émises lors de l'interaction d'un neutrino de haute énergie (> 100 GeV) avec la matière environnant le détecteur, sur base de la détection de rayonnement Cerenkov. Ce travail est basé sur les données enregistrées par AMANDA-II entre 2000 et 2006, afin de rechercher des sources cosmiques de neutrinos. Le signal recherché est affecté d'un bruit de fond important de muons et de neutrinos issus de l'interaction du rayonnement cosmique primaire dans l'atmosphère. En se limitant à l'observation de l'hémisphère nord, le bruit de fond des muons atmosphériques, absorbés par la Terre, est éliminé. Par contre, les neutrinos atmosphériques forment un bruit de fond irréductible constituant la majorité des 6100 événements sélectionnés pour cette analyse. Il est cependant possible d'identifier une source ponctuelle de neutrinos cosmiques en recherchant un excès local se détachant du bruit de fond isotrope de neutrinos atmosphériques, couplé à une sélection basée sur l'énergie, dont le spectre est différent pour les deux catégories de neutrinos. Une approche statistique originale est développée dans le but d'optimiser le pouvoir de détection de sources ponctuelles, tout en contrôlant le taux de fausses découvertes, donc le niveau de confiance d'une observation. Cette méthode repose uniquement sur la connaissance de l'hypothèse de bruit de fond, sans aucune hypothèse sur le modèle de production de neutrinos par les sources recherchées. De plus, elle intègre naturellement la notion de facteur d'essai rencontrée dans le cadre de test d'hypothèses multiples.La procédure a été appliquée sur l'échantillon final d'évènements récoltés par AMANDA-II. --------- MANDA-II is a neutrino telescope which comprises a three dimensional array of optical sensors deployed in the South Pole glacier. Its principle rests on the detection of the Cherenkov radiation emitted by charged secondary particles produced by the interaction of a high energy neutrino (> 100 GeV) with the matter surrounding the detector. This work is based on data recorded by the AMANDA-II detector between 2000 and 2006 in order to search for cosmic sources of neutrinos. A potential signal must be extracted from the overwhelming background of muons and neutrinos originating from the interaction of primary cosmic rays within the atmosphere. The observation is limited to the northern hemisphere in order to be free of the atmospheric muon background, which is stopped by the Earth. However, atmospheric neutrinos constitute an irreducible background composing the main part of the 6100 events selected for this analysis. It is nevertheless possible to identify a point source of cosmic neutrinos by looking for a local excess breaking away from the isotropic background of atmospheric neutrinos; This search is coupled with a selection based on the energy, whose spectrum is different from that of the atmospheric neutrino background. An original statistical approach has been developed in order to optimize the detection of point sources, whilst controlling the false discovery rate -- hence the confidence level -- of an observation. This method is based solely on the knowledge of the background hypothesis, without any assumption on the production model of neutrinos in sought sources. Moreover, the method naturally accounts for the trial factor inherent in multiple testing.The procedure was applied on the final sample of events collected by AMANDA-II.

Abstract In this literary, we discuss with structure and morphology improvement of GaN epilayer on c-sapphire by multi-step method in molecular-beam epitaxy. Our research is caused for the critical results of defect in GaN epilayer and rough surface morphology. In order to solve these problems we used a novel technique which we called multi-step method. In this thesis, the results of X-ray, SEM, AFM all demonstrated the achievement in our composition. However, we obtained the results of full width of half maxima (FWHM) of (0002) and (10 2) XRD rocking curves with 60~120 arcseconds and 700~ 1200 arcseconds from a series of multi-step samples respectively. Comparing with previous measurement, multi-step method is relatively superior, and the measurement of AFM roughness is under 2 nm from the series of multi-step samples. If we discuss the flat area further, we can get smoother surface which roughness is about 0.4 nm. It is obviously to recognize the flat and rough regions, but in SEM image we made sure that the flat region occupied the greater part of surface. So, in this literary we verified that the method of multi-step can improve the structure and morphology of GaN by molecular-beam epitaxy.

In this thesis, numerical experiments are performed to test the numerical stability of the finite element method for analyzing incompressible materials from boundary displacements. The significance of the study relies on the fact that incompressibility, or density preservation during deformation, is an important property of materials such as rubber and soft tissue.<p>It is well known that the finite element analysis (FEA) of incompressible materials is less straightforward than for materials which are compressible. The FEA of incompressible materials using the usual displacement based finite element method results in an unstable solution for the stress field. Hence, a different formulation called the mixed u-p formulation (u displacement, p pressure) is used for the analysis. The u-p formulation results in a stable solution but only when the forces and/or stress tractions acting on the structure are known. There are, however, certain situations in the real world where the forces or stress tractions acting on the structure are unknown, but the deformation (i.e. displacements) due to the forces can be measured. One example is the stress analysis of soft tissues. High resolution images of initial and deformed states of a tissue can be used to obtain the displacements along the boundary. In such cases, the only inputs to the finite element method are the structural geometry, material properties, and boundary displacements. When finite element analysis of incompressible materials with displacement boundary conditions is performed, even the mixed u-p formulation results in highly unstable calculations of the stress field. Here, a hypothesis for solving this problem is developed and tested. Theories of linear and nonlinear stress analysis are reviewed to demonstrate that it may be possible to determine the von Mises stress uniquely in spite of the numerical instability inherent in the calculations.<p>To validate this concept, four different numerical examples representing different deformation processes are considered using ANSYS®: a plate in simple shear; expansion of a thick-walled cylinder; a plate in uniform strain; and Cooks membrane. Numerical results show that, unlike the normal stress components Sx, Sy, and Sz, the calculated values of the von Mises stress are reasonably accurate if measurement errors in the displacement data are small. As the measurement error increases, the error in the von Mises stress increases approximately linearly for linear problems, but can become unacceptably large in nonlinear cases, to the point where solution process encounter fatal errors. A quasi-Dirichlet patch test in association with this problem is also introduced.

Determination of the stress distributions in post-core restored endodontically treated teeth is challenging due to the fact that the post and core systems, the root and its canal, and the bony structures supporting the root have small dimensions and are structurally complex. In this research, a 3D finite element model was developed to evaluate the stress distributions in a post-core restored endodontically treated maxillary incisor under various static loads. The physical model includes dentin, PDL, bone, post, core, gutta percha and crown. All materials are assumed to be homogenous, isotropic, and linear elastic. The effects of various factors on the stress distributions are investigated through simulations. These factors include post materials, post and core combinations, ferrule heights, post and dentin gaps at the coronal entrance of the canal, and canal diameters. It has been found that the horizontal loading is the most dangerous, which causes the highest stresses in dentin and posts, followed by the oblique loading and the vertical loading. The above listed factors, such as post materials, post and core combinations, ferrule heights, post and dentin gaps at the coronal entrance of the canal, and canal diameters, do not change the stress distributions and magnitudes significantly under horizontal and oblique loading. However, the stresses are sensitive to the above factors under the vertical loading, and it has been found that the stress distributions in both dentin and the post are the most uniform without stress concentrations when the elastic modules of the post and the core are similar to that of dentin. Regarding the effects of the gaps at the cervical region on the stress distributions in dentin, the high stresses at the apical portion of the root and the bottom of the gaps decrease as the increase of the depth of the gap under vertical loading. Overall, the sharp angle and notch of the gap at the coronal entrance of the canal should be avoided in tooth restoration since they can cause stress concentrations. On the effects of the ferrule heights, the changes of the stress distributions in dentin and the post are insignificant except that higher ferrule shows lower stresses at the top of the ferrule. Regarding the effects of the diameters of the posts, the results show that although the posts with large diameters support more loads, they cause high stress concentrations at the apical portion of the root, which is not desirable. / October 2005

A numerical simulation of steady and unsteady two-dimensional flows past cylinder with dimples based on highly accurate pseudospectral method is the subject of the present thesis. The vorticity-streamfunction formulation of two-dimensional incompressible Navier-Stokes equations with no-slip boundary conditions is used. The system is formulated on a unit disk using curvilinear body fitted coordinate system. Key issues of the curvilinear coordinate transformation are discussed, to show its importance in properly defined node distribution. For the space discretization of the governing system the Fourier-Chebyshev pseudospectral approximation on a unit disk is implemented. To handle the singularity at the pole of the unit disk the approach of defining the computational grid proposed by Fornberg was implemented. Two algorithms for solving steady and unsteady problems are presented. For steady flow simulations the non-linear time-independent Navier-Stokes problem is solved using the Newton's method. For the time-dependent problem the semi-implicit third order Adams-Bashforth/Backward Differentiation scheme is used. In both algorithms the fully coupled system with two no-slip boundary conditions is solved. Finally numerical result for both steady and unsteady solvers are presented. A comparison of results for the smooth cylinder with those from other authors shows good agreement. Spectral accuracy is demonstrated using the steady solver. / February 2007