This document describes radar propagation modelling using split step parabolic wave equation (PWE) method. A computer program using Fourier split-step (FSS) marching technique is developed for predicting the electromagnetic wave propagation in troposphere. The program allows specification of frequency, polarization, antenna radiation pattern, antenna altitude, elevation angle and terrain profile. Both staircase terrain modelling and conformal mapping are used to model the irregular terrain. Mixed Fourier transform is used to implement the impedance boundary conditions. The conditions and the limits of different approximations are stated. The propagation code, RPPT (Radar Propagation Prediction Tool) is developed in Matlab 6.0 with a user friendly GUI. Different PWE methods can be selected in RPPT for different applications. The results are presented as one-way propagation factor and path loss in decibels versus range.Comparisons are made between different PWE techniques and other propagation models to demonstrate the ability and accuracy of the present model to accommodate various situations. It is assumed that the reader is familiar with the tropospheric propagation.

In cryptography, periodic sequences with terms in F2 are used almost everywhere. These sequences should have large linear complexity to be cryptographically strong. In fact, the linear complexity of a sequence should be close to its period. In this thesis, we study the expected value for N-periodic sequences with terms in the finite field Fq. This study is entirely devoted to W. Meidl and Harald Niederreiter&rsquo / s paper which is &ldquo / On the Expected Value of the Linear Complexity and the k-Error Linear Complexity of Periodic Sequences&rdquo / We only expand this paper, there is no improvement. In this paper there are important theorems and results about the expected value of linear complexity of periodic sequences.

Computer simulations have emerged as a cost efficient complement to laboratory experiments, as computers have become increasingly powerful. The aim of the present work is to explore the ideas of some state of the art software development practices, and ways in which these can be useful for developing high performance research codes. The introduction of these practices, and the modular designs that they give rise to, raises issues regarding a potential conflict between runtime efficiency on one hand and development efficiency on the other. Flexible software modules, based on mathematical abstractions, will provide support for convenient implementation and modification of numerical operators. Questions still remain about whether such modules will provide the efficiency which is required for high performance applications. To answer these questions, investigations were performed within two different problem domains. The first domain consisted of modular frameworks for the numerical solution of Partial Differential Equations. Such frameworks proved a suitable setting, since several of my research questions revolved around the issue of modularity. The second problem domain was that of symmetry exploiting algorithms. These algorithms are based on group theory, and make ample use of mathematical abstractions from that field. The domain of symmetry exploiting algorithms gave us opportunities to investigate difficulties in combining modularity based on high level abstractions with low level optimizations using data layout and parallelization. In conclusion, my investigation of software development practices for the area of high performance computing has proved very fruitful indeed. I have found that none of the concerns that were raised should lead us to refrain from the use of the practices that I have considered. On the contrary, in the two case studies presented here, these practices lead to designs that perform well in terms of usability as well as runtime efficiency.

Positive-ion electrospray ionisation Fourier transform ion cyclotron resonance and ion trap mass spectrometry have been used to investigate the reactions of the flavonoids 3-hydroxyflavone, 5-hydroxyflavone, 5-methoxyflavoe, quercetin, quercitrin and rutin with monovalent Li+, Na+, K+ and Cs+, divalent Cu2+, Zn2+ and Pb2+ and trivalent La3+ and Eu3+ metal cations. The effect of capillary-skimmer potential difference and the ion residence time in the hexapole ion trap of the Fourier transform ion cyclotron resonance mass spectrometer are systematically investigated for the flavonoid-alkali and divalent metal ion experiment. It is observed that these variables impact significantly on the type of ions observed in the ESI experiments and hence the mass spectra. The binding selectivity of alkali metal ions towards 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone are determined using the results from FTICR mass spectrometry experiments. The selectivity order follows the order Li+>Na+>K+ for individual flavonoids. Collision-induced dissociation experiments are carried out by Fourier transform ion cyclotron resonance and ion trap mass spectrometry to compare the fragmentation behaviour of metal-flavonoid complexes. Low energy collision-induced dissociation experiments of the [2L+M]+ for 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone alkali metal complexes show the loss of ligand only. When the energy is increased only the lithiated dimer [2L+Li]+ for 5-methoxyflavone shows the loss of methyl radical along with the ligand. For quercitrin the predominant dissociation pathways are the loss of rhamnose for Li+, Na+ and K+ complexes although aglycone loss is also observed for the K+ complex. The favourable dissociation pathways for rutin are the loss of disaccharide, aglycone and rhamnose for the Na+ complex and the loss of disaccharide for the K+ complex. Collision-induced dissociation data are also used to determine the threshold dissociation energies for displacement of one flavonoid ligand from alkali metal flavonoid complexes. The threshold dissociation energies for loss of one ligand from [2L+M]+ of 5-methoxyflavone and quercitrin follow the order Li+ > Na+ > K+, rutin follows the order Na+ > K+ > Li+ , and 3-hydroxyflavone and 5-hydroxyflavone follow the order Li+ > Na+. For the same metal cation experiment, 5-methoxyflavone system has the highest dissociation energy compared to the 3-hydroxyflavone and 5-hydroxyflavone experiment. Preliminary DFT calculations show that the calculated dissociation energies follow the same trend as the experimental dissociation energies for the simple flavonoid alkali metal cation experiments. For 5-methoxyflavone-divalent metal cation (Zn2+, Cu2+ and Pb2+) complexes loss of methyl radical is the common process. CO loss is also observed for the Zn2+ complex whereas CHO and H2O losses are observed for Cu2+. For 3-hydroxyflavone and 5-hydroxyflavone divalent metal cation experiments loss of ligand is the dominant process. Zn2+ and Cu2+ complexes also show CO loss. La3+ and Er3+ with the same flavonoids show the ligand as the dominant product. For quercetin-divalent metal cation experiment, ligand loss is the dominant process. For quercitrin and rutin various dissociation products are observed where the dissociation occurs via the loss of the rhamnose and/or the disaccharide moieties. Similar dissociation patterns are also observed for La3+ and Er3+ complexes for quercitrin and rutin.

Thesis (M.E.-Res.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: p. 164-179.

Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

<p>This dissertation focuses on a FFT based forward EM solver and its application in inverse problems. The main contributions of this work are two folded. On the one hand, it presents the first scaled lab experiment system in the oil and gas industry for through casing hydraulic fracture evaluation. This system is established to validate the feasibility of contrasts enhanced fractures evaluation. On the other hand, this work proposes a FFT based VIE solver for hydraulic fracture evaluation. This efficient solver is needed for numerical analysis of such problem. The solver is then generalized to accommodate scattering simulations for anisotropic inhomogeneous magnetodielectric objects. The inverse problem on anisotropic objects are also studied.</p><p>Before going into details of specific applications, some background knowledge is presented. This dissertation starts with an introduction to inverse problems. Then algorithms for forward and inverse problems are discussed. The discussion on forward problem focuses on the VIE formulation and a frequency domain solver. Discussion on inverse problems focuses on iterative methods.</p><p>The rest of the dissertation is organized by the two categories of inverse problems, namely the inverse source problem and the inverse scattering problem. </p><p>The inverse source problem is studied via an application in microelectronics. In this application, a FFT based inverse source solver is applied to process near field data obtained by near field scanners. Examples show that, with the help of this inverse source solver, the resolution of unknown current source images on a device under test is greatly improved. Due to the improvement in resolution, more flexibility is given to the near field scan system.</p><p>Both the forward and inverse solver for inverse scattering problems are studied in detail. As a forward solver for inverse scattering problems, a fast FFT based method for solving VIE of magnetodielectric objects with large electromagnetic contrasts are presented due to the increasing interest in contrasts enhanced full wave EM imaging. This newly developed VIE solver assigns different basis functions of different orders to expand flux densities and vector potentials. Thus, it is called the mixed ordered BCGS-FFT method. The mixed order BCGS-FFT method maintains benefits of high order basis functions for VIE while keeping correct boundary conditions for flux densities and vector potentials. Examples show that this method has an excellent performance on both isotropic and anisotropic objects with high contrasts. Examples also verify that this method is valid in both high and low frequencies. Based on the mixed order BCGS-FFT method, an inverse scattering solver for anisotropic objects is studied. The inverse solver is formulated and solved by the variational born iterative method. An example given in this section shows a successful inversion on an anisotropic magnetodielectric object. </p><p>Finally, a lab scale hydraulic fractures evaluation system for oil/gas reservoir based on previous discussed inverse solver is presented. This system has been setup to verify the numerical results obtained from previously described inverse solvers. These scaled experiments verify the accuracy of the forward solver as well as the performance of the inverse solver. Examples show that the inverse scattering model is able to evaluate contrasts enhanced hydraulic fractures in a shale formation. Furthermore, this system, for the first time in the oil and gas industry, verifies that hydraulic fractures can be imaged through a metallic casing.</p> / Dissertation

La théorie d'homogénéisation élastodynamique des matériaux hétérogènes initiée par J.R. Willis il y a environ une trentaine d'années a récemment reçu une très grande attention. D'après cette théorie qui est mathématiquement exacte, la loi constitutive homogénéisée est non locale en espace et en temps ; le tenseur des contraintes dépend non seulement du tenseur des déformations mais aussi de la vitesse ; la quantité du mouvement dépend à la fois de la vitesse et du tenseur des déformations, faisant apparaître en général une masse anisotrope. Ces propriétés constitutives effectives, qui pourraient être surprenantes d'un point de vue mécanique classique, se révèlent en fait très utiles pour la conception de métamatériaux acoustiques et de capes acoustiques. Ce travail de thèse consiste essentiellement à proposer et développer deux méthodes numériques efficaces pour déterminer les propriétés élastodynamiques effectives des matériaux périodiquement hétérogènes. La première méthode relève de la méthode des éléments finis alors que la deuxième méthode est basée sur la transformée de Fourier rapide. Ces deux méthodes sont d'abord élaborées pour une microstructure périodique 3D quelconque et ensuite implantées pour une microstructure périodique 2D quelconque. Les avantages et les inconvénients de chacune de ces deux méthodes sont comparés et discutés. A l'aide des méthodes numériques élaborées, la théorie de Willis est appliquée au calcul élastodynamique sur un milieu infini hétérogène et celui homogénéisé. Les différents cas d'homogénéisabilité et de non-homogénéisabilité sont discutés / The elastodynamic homogenization theory of heterogeneous materials initiated by J.R. Willis about thirty years ago has recently received considerable attention. According to this theory which is mathematically exact, the homogenized constitutive law is non-local in space and time; the stress tensor depends not only on the strain tensor but also on the velocity; the linear momentum depends on both the velocity and the strain tensor, making appear an anisotropic mass tensor in general. These effective constitutive properties, which may be surprising from a classical mechanical point of view, turn out in fact to be very useful for the design of acoustic metamaterials and acoustic cloaks. The present work is essentially to propose and develop two efficient numerical methods for determining the effective elastodynamic properties of periodically heterogeneous materials. The first method belongs to the finite element method while the second method is based on the fast Fourier transform. These two methods are first developed for any 3D periodic microstructure and then implanted for any 2D periodic microstructure. The advantages and disadvantages of each of these two methods are compared and discussed. Using the elaborated numerical methods, the Willis theory is applied to the elastodynamic computation over the infinite heterogeneous medium and the homogenized one. The various cases of homogeneisability and non-homogeneisability are discussed

Ce travail est dédié au calcul des propriétés de transfert thermique et de transport dans les milieux hétérogènes périodiques. Les résultats sont établis dans le cadre d'homogénéisation périodique pour lequel les propriétés macroscopiques sont obtenues par la résolution de problèmes élémentaires pour la cellule irréductible. Plusieurs contributions sont ainsi apportées, visant à établir de nouvelles estimations par des approches analytiques ou en développant des méthodes numériques adaptées. Ainsi dans une première partie, on s'intéresse à la modélisation des propriétés non linéaires de filtration dans les milieux poreux. A l'échelle microscopique l'écoulement est régi par l'équation de Navier-Stokes. En développant la solution en série, on obtient par homogénéisation, une loi de filtration polynomiale. Tous les coefficients constitutifs de cette loi sont alors obtenus en résolvant en cascade des problèmes élémentaires sur la cellule à l'aide de schémas itératifs utilisant sur la transformée de Fourier rapide. On propose ensuite de nouvelles expressions analytiques pour les propriétés de conductivité thermique de composites périodiques renforcés par des inclusions sphériques. On résout l'équation intégrale de Lippmann-Schwinger par des développements en série de Neumann et en choisissant une polarisation constante dans les inclusions. Des expressions analytiques sont alors obtenues pour diverses configurations spatiales : réseaux cubiques et répartitions aléatoires isotropes. Dans la dernière partie de ce travail, on détermine les propriétés de transfert thermique par conduction et convection dans les milieux poreux saturés par un fluide. A nouveau, on propose des schémas de résolution basés sur la transformée de Fourier rapide pour le calcul du tenseur de diffusivité de milieux poreux / In this work, we determine the macroscopic properties of thermal transfer and mass transport in periodic heterogeneous materials. All the results are established in the framework of periodic homogenization, for which, the macroscopic properties are deduced by solving elementary problems for the irreducible cell. Various contributions are provided, leading to the derivation of new closed-form expressions for the effective properties or by developing numerical tools. In the first part, we determine the nonlinear filtration properties of porous media. At the microscopic scale, the fluid flow obeys to the Navier-Stokes equation. By expanding the solution into power series, we obtain, after homogenization, a polynomial type macroscopic filtration law. All the constitutive coefficients of are determined by solving a hierarchy of cell problems by means of a numerical approach based on the Fast Fourier Transform algorithm. The problem of conductivity of periodic composites reinforced by spherical inclusions is thereafter considered by an analytic approach. We solve the Lippmann-Schwinger integral equation using Neumann series and a constant polarization in the inclusion. Closed-form estimate of the macroscopic conductivity are then obtain for different spatial configurations: cubic lattice and isotropic distribution of inclusions. In the last part, we determine the thermal transfer properties by conduction and convection of porous media fulfilled by a viscous fluid. Again, numerical tools based on FFT are considered to solve the unit cell problems and to compute the diffusivity tensor

The present work represents both: a design proposal and a proposal for design.Today we are exposed to more and louder noise than ever before in all areas of human life, which alters the environment, our health and the quality of social interaction to the worse. Therefore, this project takes its departure point in the concept of Stille (German for stillness and silence) in order to oppose this culture of noise. Our surroundings influence our actions and vice versa we alter these surroundings with our actions. However, since constructed within every detail, they do not allow a transient feedback to take place naturally. A possible otherness is hardly attainable in an overly planned reality.This thesis seeks to transcend the boundaries where descriptive language ceases to function and introduces materiality and interactive devices to evoke other avenues of reflection where the boundaries of actor, context and artefact converge. The proposal at hand embodies the fundamental principles of Stille in order to exploit aspects of parametric design and contingency. It imagines and materialises alternative ways of a potentially open process in which our physical environment could continuously constitute itself. Both hidden and apparent aspects of reality are unraveled and transformed into artifacts. The work depicts the transient complexity of reality and the contingent influence of everyone on our surroundings. How is our behaviour altered by the materialisation of ideas? How receptive is the current design practice to a constantly changing reality?