Dissertations / Theses on the topic 'Hill function'

The middle landscape, more commonly referred to as Suburbia, has become spatially discontinuous, lacking the cohesive union, open spaces and city centers that once defined community. Presently, the middle landscapeâ s community spaces do not offer the opportunity for familiar and chance encounters or ritual activity. Large-scale housing development in Northern Virginia and in the mid-Atlantic region is continually segregating and ultimately destroying community and all links to the areaâ s history. Located in Southern Fairfax County, the newly abandoned Lorton Central and Maximum Security Prison Facility provides an opportunity to serve as a catalyst for community in this area. This thesis investigates the historic precedence for creating successful community centers. The authorâ s personal investigation is focused upon using form and function to accomplish this vision. By adaptively reusing the existing architecture alongside new construction, the intent is to create a dense urban town center at the abandoned historic site.<br>Master of Landscape Architecture

As autonomy increases in today’s vehicles, the demands increase on both safety and comfort functions. Vehicle Hold, which holds the vehicle stationary without requiring the driver to press the brake pedal, is an example of such as function. This thesis aims to develop a concept for a Drive Away Release from this hold state, following several requirements regarding such as rollback, comfort, manual and autonomous drive mode, driving direction, road inclinations, with or without a trailer, and following the safety standard ISO 26262. In order to develop the concept function, a study of the state-of-the-art was made, followed by modeling the dynamics and control. The control algorithm was validated and tested first by running co-simulations between Matlab/Simulink and CarMaker. It was then implemented in a test vehicle. The test vehicle did not have all systems which are usually provided, demanding estimations to be made, such as the road inclination and vehicle mass. For manual drive mode, the driver controls the propulsion torque, and the control algorithm is based on releasing the brakes depending on estimations of the gravitational and propulsion torques. For autonomous drive mode, the vehicle is supposed to follow an acceleration reference. The control algorithm for autonomous drive mode is then extended with two feedforward compensators, one from reference and one from the gravitational torque, which is regarded as a disturbance, and with a feedback PI controller. To ensure that rollback do not occur at drive away release, a rollback prevention safety feature was also developed. The results of both the simulations and the test drives show that the concept function provides comfortable drive-off for most inclinations, drive modes and directions, without causing an undesired rollback

Au cours des dernières années, des changements importants dans le domaine des assurances et des finances attirent de plus en plus l’attention sur la nécessité d’élaborer un cadre normalisé pour la mesure des risques. Récemment, il y a eu un intérêt croissant de la part des experts en assurance sur l’utilisation de l’espérance conditionnelle des pertes (CTE) parce qu’elle partage des propriétés considérées comme souhaitables et applicables dans diverses situations. En particulier, il répond aux exigences d’une mesure de risque “cohérente”, selon Artzner [2]. Cette thèse représente des contributions à l’inférence statistique en développant des outils, basés sur la convergence des intégrales fonctionnelles, pour l’estimation de la CTE qui présentent un intérêt considérable pour la science actuarielle. Tout d’abord, nous développons un outil permettant l’estimation de la moyenne conditionnelle E[X|X > x], ensuite nous construisons des estimateurs de la CTE, développons la théorie asymptotique nécessaire pour ces estimateurs, puis utilisons la théorie pour construire des intervalles de confiance. Pour la première fois, l’approche de bootstrap non paramétrique est explorée dans cette thèse en développant des nouveaux résultats applicables à la valeur à risque (VaR) et à la CTE. Des études de simulation illustrent la performance de la technique de bootstrap.

In the classic Hill model for muscle contraction, the split between the muscle and tendon is arbitrary and the problem lacks a unique solution. Instead of reformulating the problem to a differential-algebraic equation and solving for a set of initial conditions, a constant tendon length is commonly assumed in musculoskeletal simulation tools. This assumption has not been thoroughly tested and introduces errors of unknown magnitude to the simulations. In this thesis, the contractile element of the Hill model is modelled as a friction clutch in parallel to a viscous damper. This provides an evolution law for the muscle length by which the muscle speed is numerically calculated taking into account a non-zero tendon speed. A simple biceps curl is simulated with the friction clutch model and compared to corresponding commercial musculoskeletal simulations. Overall, the results are similar, in particular for the muscle lengths which are almost identical in every simulation (0.00-0.42% difference). The difference in tendon speed is 0.00-3.26%, with upwards tendencies. In general, the error percentage of the tendon speed appears to decrease by the same amount that the contraction speed is reduced. Conclusively, it can be said that the introduced friction clutch model delivers comparative outcomes to a commercial musculoskeletal simulation software, while not assuming a constant tendon length. However, while presenting a relatively simple solution, an increased computation time is to be expected due to the need of a differential equation solver. Further investigation regarding implementation and computing times in more complex simulations may provide an alternative approach to conventional musculoskeletal simulations.

Fundamental to the electronic security of information and communication systems, is the correct use and application of appropriate ciphers. The strength of these ciphers, particularly in their ability to resist cryptanalytic attacks, directly in uences the overall strength of the entire system. The strength of the underlying cipher is reliant upon a robust structure and the carefully designed interaction between components in its architecture. Most importantly, however, cipher strength is critically dependent on the strength of the individual components of which it is comprised. Boolean functions and substitution boxes (s-boxes) are among the most common and essential components of ciphers. This is because they are able to provide a cipher with strengthening properties to resist known and potential cryptanalytic attacks. Thus, it is not surprising that significant research effort has been made in trying to develop ways of obtaining boolean functions and substitution boxes with optimal achievable measures of desirable cryptographic properties. Three of the main cryptographic properties required by strong boolean functions and s-boxes are nonlinearity, correlation immunity and propagation criteria, with different cryptographic applications requiring different acceptable measures of these and other properties. As combinations of cryptographic properties exhibited by functions can be conicting, finding cryptographically strong functions often means that a trade-off needs to be made when optimizing property values. Throughout this thesis, the term "optimization" specifically refers to seeking to obtain the best achievable combination of target property values which may be exhibited by boolean functions and s-boxes, regardless of whether the relevant properties are conflicting or complementary. This thesis focusses on a particular class of techniques for obtaining strong functions for cryptographic applications, referred to as heuristic methods or, simply, heuristics. Three new heuristic methods, each aimed at generating boolean functions optimizing one or more of the main cryptographic properties mentioned above, in addition to other desirable properties, are presented. The first of the new heuristic methods developed for this thesis focusses on generating boolean functions which are balanced and exhibit very high nonlinearities. Highly nonlinear balanced functions are critical to many cryptographic applications, as they provide good resistance to linear cryptanalytic attacks. This first method is based on the recursive modification of a starting bent function and is shown to be highly successful and efficient at generating numerous such functions, which also exhibit low autocorrelation values, in a very short computational time. The generation of balanced, correlation immune boolean functions that also exhibit the confl icting property of high nonlinearity is the focus of the second new heuristic method developed for this thesis. By concatenating selected pairs of lower-dimensional boolean functions together in the Walsh Hadamard transform domain, direct optimization for both resilience and nonlinearity was able to take place at each level towards and for the final function. This second method was able to generate examples of boolean functions with almost all of the best known optimal combinations of target property values. Experiments have shown the success of this method in consistently generating highly nonlinear resilient boolean functions, for a range of orders of resilience, with such functions possessing optimal algebraic degree. A third new heuristic method, which searches for balanced boolean functions which satisfy a non-zero degree of propagation criteria and exhibit high nonlinearity, is presented. Intelligent bit manipulations in the truth table of starting functions, based on fundamental relationships between boolean function transforms and measures, provide the design rationale for this method. Two new function generation schemes have been proposed for this method, to efficiently satisfy the requirements placed on the starting functions utilized in the computational process. An optional process attempts to increase the algebraic degree of the resulting functions, without sacrificing the optimalities that are achievable. The validity of this method is demonstrated through the success of various experimental trials. Switching the focus from single output boolean functions to multiple output boolean functions (s-boxes), the effectiveness of existing heuristic techniques (namely Genetic Algorithm, Hill Climbing Method and combined Genetic Algorithm/Hill Climbing) in primarily being applied to improve the nonlinearity of s-boxes of various dimensions, is investigated. The prior success of these heuristic techniques for improving the nonlinearity of boolean functions has been previously demonstrated, as has the success of hill climbing in isolation when applied to bijective s-boxes. An extension to the bijective s-box optimization work is presented in this thesis. In this new research, a Genetic Algorithm, Hill Climbing Method and the two in combination are applied to the nonlinearity and autocorrelation optimization of regular NxM s-boxes (N > M) to investigate the effectiveness and efficiency of each of these heuristics. A new breeding scheme, utilized in the Genetic Algorithm and combined Genetic Algorithm/Hill Climbing trials, is also presented. The success of experimental results compared to random regular s-box generation is demonstrated. New research in applying the Hill Climbing Method to construct NxM sboxes (N > M) required to meet specific property criteria is presented. The consideration of the characteristics desired by the constructed s-boxes largely dictated the generation process. A discussion on the generation process of the component functions is included. Part of the results produced by experimental trials were incorporated into a commonly used family of stream ciphers, thus further supporting the use of heuristic techniques as a useful means of obtaining strong functions suitable for incorporation into practical ciphers. An analysis of the cryptographic properties of the s-box used in the MARS block cipher, the method of generation and the computational time taken to obtain this s-box, led to the new research reported in this thesis on the generation of MARS-like s-boxes. It is shown that the application of the Hill Climbing Method, with suitable requirements placed on the component boolean functions, was able to generate multiple MARS-like s-boxes which satisfied the MARS sbox requirements and provided additional properties. This new work represented an alternative approach to the generation of s-boxes satisfying the MARS sbox property requirements but which are cryptographically superior and can be obtained in a fraction of the time than that which was taken to produce the MARS s-box. An example MARS-like s-box is presented in this thesis. The overall value of heuristic methods in generating strong boolean functions and substitution boxes is clearly demonstrated in this thesis. This thesis has made several significant contributions to the field, both in the development of new, specialized heuristic methods capable of generating strong boolean functions, and in the analysis and optimization of substitution boxes, the latter achieved through applying existing heuristic techniques.

In spite of remarkable progress in molecular biology, our understanding of the dynamics and functions of intra- and inter-cellular biological networks has been hampered by their complexity. Kinetics modelling, an important type of mathematical modelling, provides a rigorous and reliable way to reveal the complexity of biological networks. In this thesis, two genetic regulatory networks have been investigated via kinetic models. In the first part of the study, a model is developed to represent the transcriptional regulatory network essential for the circadian rhythms in Drosophila. The model incorporates the transcriptional feedback loops revealed so far in the network of the circadian clock (PER/TIM and VRI/PDP1 loops). Conventional Hill functions are not used to describe the regulation of genes, instead the explicit reactions of binding and unbinding processes of transcription factors to promoters are modelled. The model is described by a set of ordinary differential equations and the parameters are estimated from the in vitro experimental data of the clocks’ components. The simulation results show that the model reproduces sustained circadian oscillations in mRNA and protein concentrations that are in agreement with experimental observations. It also simulates the entrainment by light-dark cycles, the disappearance of the rhythmicity in constant light and the shape of phase response curves resembling that of experimental results. The model is robust over a wide range of parameter variations. In addition, the simulated E-box mutation, perS and perL mutants are similar to that observed in the experiments. The deficiency between the simulated mRNA levels and experimental observations in per01, tim01 and clkJrk mutants suggests some differences in the model from reality. Finally, a possible function of VRI/PDP1 loops is proposed to increase the robustness of the clock. In the second part of the study, the sources of intrinsic noise and the influence of extrinsic noise are investigated on an intracellular viral infection system. The contribution of the intrinsic noise from each reaction is measured by means of a special form of stochastic differential equation, the chemical Langevin equation. The intrinsic noise of the system is the linear sum of the noise in each of the reactions. The intrinsic noise arises mainly from the degradation of mRNA and the transcription processes. Then, the effects of extrinsic noise are studied by means of a general form of stochastic differential equation. It is found that the noise of the viral components grows logarithmically with increasing noise intensities. The system is most susceptible to noise in the virus assembly process. A high level of noise in this process can even inhibit the replication of the viruses. In summary, the success of this thesis demonstrates the usefulness of models for interpreting experimental data, developing hypotheses, as well as for understanding the design principles of genetic regulatory networks.

This diploma thesis deals with creation of elektromechanical model in Modelica language which is subsequently imported into LabVIEW environment. The Modelica language, LabVIEW graphical programming tool and Functional Mock-up Interface 2.0 standard are described in the introduction of this thesis. Functional Mock-up Interface is a tool independent standard witch, defines a standardized interface to ModelExchange and Co-simulation of complex system components. The model of electromechanical system was created based on Functional Mock-up Interface standard. Part of the work focuses on the Functional Mock-up Unit storage possibilities and LabVIEW support to import models of this type. The imported model was simulated and tested in this environment. Finally, the instance of Functional Mock-up Unit was connected with LabVIEW FPGA target for the purpose of model HIL simulation on CompactRIO platform.

<p>In recent years Hardware-in-the-Loop HiL, has gained more and more</p><p>popularity within the vehicle industry. This is a more cost effective research alternative, as opposed to the tests done the traditional way, since in HiL testing the idea is to test the hardware of interest, such as an electronic control unit, in a simulated (or partially simulated) environment which closely resembles the real-world environment.</p><p>This thesis is ordered by Daimler Chrysler AG and the objective of this thesis is the developing of a cylinder-by-cylinder model for the purpose of emulation of misfire in a four-stroke SI-engine. This purpose does not demand a precise modelling of the cylinder pressure but rather an adequate modelling of position and amplitude of the torque produced by each cylinder. The model should be preferebly computaionally tractable so it can be run on-line. Therefore, simplifications are made such as assuming the rule of a homogenous mixture, pressure and temperature inside the cylinder at all steps, so the pressure model can be analytical and able to cope with the real-time demand of the HiL. The model is implemented in Simulink and simulated with different sample rates and an improvement is to be seen as the sample rate is decreased.</p>

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-23T16:38:50Z No. of bitstreams: 1 arquivototal.pdf: 1943524 bytes, checksum: 935ea8764b03a0cab23d8c7c772a137d (MD5)<br>Made available in DSpace on 2017-08-23T16:38:50Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1943524 bytes, checksum: 935ea8764b03a0cab23d8c7c772a137d (MD5) Previous issue date: 2016-03-08<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>This work is divided into three parts. In the first part, we investigate the behavior of the constants of the Bohnenblust–Hille and Hardy–Littlewood polynomial and multilinear inequalities. In the second part, we show an optimal spaceability result for a set of non-multiple summing forms on `p and we also generalize a result related to cotype (from 2010) as highlighted by G. Botelho, C. Michels, and D. Pellegrino. Moreover, we prove new coincidence results for the class of absolutely and multiple summing multilinear operators (in particular, we show that the well-known Defant–Voigt theorem is optimal). Still in the second part, we show a generalization of the Bohnenblust–Hille and Hardy–Littlewood multilinear inequalities and we present a new class of summing multilinear operators, which recovers the class of absolutely and multiple summing operators. In the third part, it is proved the existence of large algebraic structures inside, among others, the family of Lebesgue measurable functions that are surjective in a strong sense, the family of non-constant di↵erentiable real functions vanishing on dense sets, and the family of noncontinuous separately continuous real functions.<br>Este trabalho est´a dividido em trˆes partes. Na primeira parte, investigamos o comportamento das constantes das desigualdades polinomial e multilinear de Bohnenblust–Hille e Hardy–Littlewood. Na segunda parte, mostramos um resultado ´otimo de espa¸cabilidade para o complementar de uma classe de operadores m´ultiplo somantes em `p e tamb´em generalizamos um resultado relacionado a cotipo (de 2010) devido a G. Botelho, C. Michels e D. Pellegrino. Al´em disso, provamos novos resultados de coincidˆencia para as classes de operadores multilineares absolutamente e m´ultiplo somantes (em particular, mostramos que o famoso teorema de Defant–Voigt ´e ´otimo). Ainda na segunda parte, mostramos uma generaliza¸c˜ao das desigualdades multilineares de Bohnenblust–Hille e Hardy–Littlewood e apresentamos uma nova classe de operadores multilineares somantes, a qual recupera as classes dos operadores multilineares absolutamente e m´ultiplo somantes. Na terceira parte, provamos a existˆencia de grandes estruturas alg´ebricas dentro de certos conjuntos, como, por exemplo, a fam´ılia das fun¸c˜oes mensur´aveis `a Lebesgue que s˜ao sobrejetivas em um sentido forte, a fam´ılia das fun¸c˜oes reais n˜ao constantes e diferenci´aveis que se anulam em um conjunto denso e a fam´ılia das fun¸c˜oes reais n˜ao cont´ınuas e separadamente cont´ınuas.

This diploma thesis is focused on testing of Electronic Control Units, especially functional testing in which hardware and software is verified and also Model in the Loop, Software in the Loop, Processor in the Loop and Hardware in the Loop testing methods. Within practical part of this thesis testing stand for functional test of the ECU was developed and manufactured. It is connected to PC via Input/Output card, testing is controlled by MATLAB script. Whole process of testing is automated from initial upload of testing firmware to tested ECU over all phases of test up to bootloader flashing. Hardware in the Loop test was also created, in which ECU works as controller and DC motor is simulated in real time with PC in MATLAB environment.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-04-26T16:24:39Z No. of bitstreams: 1 Luiz Eduardo Steffens_.pdf: 2734317 bytes, checksum: 7ce3824925bb95a8b45268be640b5233 (MD5)<br>Made available in DSpace on 2018-04-26T16:24:39Z (GMT). No. of bitstreams: 1 Luiz Eduardo Steffens_.pdf: 2734317 bytes, checksum: 7ce3824925bb95a8b45268be640b5233 (MD5) Previous issue date: 2006-05-31<br>UNISINOS - Universidade do Vale do Rio dos Sinos<br>No Rio Grande do Sul, a erva-mate, Ilex paraguariensis St. Hil. (Aquifoliaceae), é um dos componentes nativos da floresta ombrófila mista e tem importância sócio-econômica e ambiental. Este trabalho objetivou inventariar e comparar a riqueza e composição de táxons de formigas em quatro formas de cultivo de erva-mate: nativa, consorciada, monocultivo com e sem aplicação de herbicida e determinar os padrões de ocorrência e de dominância, e o status dos táxons. Durante 12 meses, em cada forma de cultivo, foram amostradas aleatoriamente dez árvores, utilizando-se guarda-chuva entomológico com esforço amostral de 20 batidas por erveira. Paralelamente, com a rede entomológica de varredura foram feitas coletas na vegetação entre as erveiras com 100 redadas por forma de cultivo. Dos 35 táxons registrados, 27 foram encontrados nos ervais nativos, 26 nos monocultivos com aplicação de herbicida, 19 nos de monocultivo e 18 nos ervais consorciados. Quatorze (40,0 %) foram comuns a todas as formas de cultivo, seis (17,1 %) foram exclusivos no cultivo nativo, quatro (11,4 %) no erval com aplicação de herbicida e tanto o erval consorciado, quanto o monocultivo apresentaram apenas um táxon (2,8 %) exclusivo. Ocorreu diferença significativa (p=0,031) apenas entre as comunidades de formigas dos ervais nativo e consorciado. A subfamília melhor representada foi Myrmicinae com 17 gêneros. A similaridade entre as comunidades de formigas dos ervais com aplicação de herbicida e monocultivo foi a mais alta (Sj=71,8 %). A maioria dos táxons foi categorizada como acidental e dominante, com status intermediário. A distribuição dos grupos funcionais apresentou grande semelhança entre as quatro comunidades, sugerindo que a forma de cultivo interfere mais sobre a riqueza de táxons do que sobre a estrutura funcional das comunidades de formigas.<br>In the Rio Grande do Sul State, the maté, Ilex paraguariensis St. Hil. (Aquifoliaceae), is one of the main native components of the mixed ombrophilous forest understory with social-economical and environmental value. The present study aimed at surveying and comparing the ant species richness and composition among four differently cultivated maté fields: native, intercropping system, monoculture and herbicide treated, determining the occurrence and the dominance patterns and the species status. In each fields, ten maté trees were randomly sampled during 12 months using beating tray with a sample effort of 20 beatings per tree. At the same time, 100 sweeps using the entomologic net sampled the vegetation between the maté trees per field. Of the 35 taxa collected, 27 occurred in the native fields, 26 in the herbicide treated fields, 19 in the monoculture and 18 taxa in the mixed culture fields. Fourteen (40.0 %) were common to all cultivation techniques, six (17.1 %) were exclusive to the native fields and four (11.4 %) in the herbicide treated fields. A single exclusive taxon (2.8 %) occurred in the areas of herbicide treatment, mixed culture and monoculture. The native field differed significantly (p=0.031) from the mixed one. The subfamily Myrmicinae was the most representative with 17 genera. The herbicide treated and the monoculture fields had the highest similarity (Sj=71.8 %). Most of the species status was categorized as accidental, dominant and as intermediate. The functional groups distribution presented great similarity among the four ant communities, suggesting that the cultivation form interferes more on the wealth of species than on the functional structure of the ants.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>In this work, we first develop a brief theoretical approach of semigroups of bounded linear operators, culminating on Hille-Yosida Theorem. Then we used the extrapolation theory to study su cient conditions to obtain existence and uniqueness of Almost Automorphic and Pseudo-Almost Automorphic mild solutions, through the Banach's Fixed Point Theorem for the semilinear evolution equation x(t) = Ax(t) + f(t; x(t)); t E R, where A : D(A) X ! X is a Hille-Yosida operator of negative type and not necessary dense domain on the Banach space X.<br>Neste trabalho, desenvolvemos inicialmente uma breve abordagem te orica dos semigrupos de operadores lineares limitados, culminando no Teorema de Hille-Yosida. Em seguida, usamos a teoria de extrapolação a fim de estudar condições suficientes para obtermos a existência e a unicidade de soluções brandas Quase Automórficas e Pseudo-quase Automórficas, por meio do Teorema do Ponto Fixo de Banach, para a equação de evolução semilinear x(t) = Ax(t) + f(t; x(t)); t E R, onde A : D(A) X ! X é um operador de Hille-Yosida de tipo negativo e dom ínio não necessariamente denso, definido no espaço de Banach X.

Cette thèse est consacrée à la modélisation de la turbulence avec des approches hybrides RANS-LES. Ces approches permettent d’assurer le meilleur compromis entre, d’une part, la capacité de la LES à capturer les structures instationnaires dans les régions d'intérêt de l’écoulement, et, d’autre part, un coût de calcul abordable en activant le mode RANS lorsque la résolution LES n’est pas nécessaire ou trop coûteuse, notamment en paroi. L’objectif industriel pour EDF est d’utiliser ces méthodes pour estimer les efforts instationnaires qui s’exercent sur certains gros composants (GMPP) des réacteurs à eau pressurisée.En premier lieu, une nouvelle formulation du modèle hybride HTLES (Hybrid Temporal Large-Eddy Simulation) est développée, dans le but d’améliorer ses fondations théoriques, en utilisant le critère de H-Equivalence. L'intérêt de ce modèle réside dans l'utilisation du filtrage temporel pour contrôler la répartition d’énergie entre les échelles résolues et modélisées, permettant de garantir la consistance entre les opérateurs RANS et LES. L’approche hybride est appliquée à différents modèles de fermeture RANS, et la calibration est effectuée sur la décroissance d'une turbulence homogène isotrope. De plus, des développements analytiques similaires permettent de proposer, pour la première fois, un modèle hybride fondé sur une modification d’échelle dans une formulation RANS qui tend explicitement vers un modèle LES préexistant.Le contrôle de la transition RANS-LES dans les régions de proche paroi est une problématique majeure de cette thèse. Afin d’améliorer le comportement du modèle HTLES, une fonction de protection double (dépendante à la fois de paramètres physiques et de critères liés aux maillages) et une contrainte de consistance interne sont proposées pour imposer le mode RANS en paroi lorsque la résolution LES n’est pas appropriée. Le modèle amélioré est validé sur les écoulements en canal plan et sur les collinespériodiques, avec des résultats très satisfaisants et robustes vis-à-vis du raffinement du maillage. Il est de plus montré pour le cas test des collines périodiques que des fluctuations turbulentes résolues dans la zone LES pénètrent dans la région RANS de proche paroi sans être trop altérées. Cela permet de capturer correctement les basses fréquences des spectres d'énergie turbulente et de pression en paroi, ce qui s'avère décisif dans le but d'estimer les efforts instationnaires sur des composants. Finalement, la HTLES offre une méthode de résolution alternative au coût numérique réduit par rapport à un modèle LES résolu en paroi.Enfin, la thèse s'intéresse à une version zonale de la HTLES (imposant le mode RANS dans les régions où la résolution LES n'est pas nécessaire), en appliquant le ALF (Anisotropic Linear Forcing) au niveau des interfaces RANS-HTLES afin de promouvoir l'apparition de fluctuations turbulentes résolues. Cette première étude de faisabilité offre des résultats prometteurs.Résumé en<br>This work is devoted to turbulence modelling using hybrid RANS-LES approaches. These approaches offer the best potential to reach the compromise between the capability of LES to capture the large-scale structures in regions of interest, and the low-computational cost of RANS calculations in regions where LES resolution is not required or too CPU-demanding, notably in near-wall regions. The industrial objective for EDF is to use these methods to predict unsteady loads on large components (reactor coolant pumps) of pressurized water reactors.In this regard, a new formulation of HTLES (Hybrid Temporal Large-Eddy Simulation) is developed, in order to improve the theoretical foundation of the model, applying the Hybrid-Equivalence criterion. The interest of this model lies in the use of temporal filtering, to control the energy partition between resolved and modeled scales, ensuring a consistent bridging between RANS and LES models. The HTLES approach is applied to several RANS models, and the model is calibrated in decaying isotropic turbulence. In addition, a similar analysis shows for the first time that it is possible, from theoretical considerations, to derive a hybrid RANS-LES model based on scale modifications in a RANS model, which explicitly tends towards a standard LES model in LES regions.The control of the RANS-to-LES transition in near-wall regions is a major concern in this work. In order to improve the behavior of the HTLES model, a two-fold shielding function (depending on physical parameters and mesh criteria) and an internal consistency constraint are introduced, aiming at enforcing the RANS mode when the activation of the LES mode is not suitable. The validation process of the upgraded version of the model is carried out on channel and periodic-hill flows, reaching the expected outcomes: accuracy of the predictions and robustness of HTLES to grid coarsening. Moreover, it is shown that resolved vortices coming from the LES zone penetrates into the near-wall RANS region down to the wall, enabling the hybrid model to fairly reproduce the low frequencies. The capacity of HTLES to provide information on energy and pressure spectra at the wall is assessed, which is decisive to predict unsteady loads. Hence, HTLES offers a cost-saving alternative to a wall-resolved LES.Finally, the work focuses on a zonal control of HTLES (enforcing the RANS mode in large portions of the domain where the LES mode is not required), applying the ALF (Anisotropic Linear Forcing) at the RANS-to-HTLES interfaces to promote turbulent fluctuations. This feasibility study offers promising results

Cette thèse s’intéresse aux liens entre réseaux d’interactions en écologie, espace et temps. On assiste à un changement croissant de représentation d’un communauté d’espèces, d’un ensemble d’espèces à un ensemble d’espèces et leurs interactions : un réseau d’interactions. On s’attachera alors à élaborer les prémisses d’une théorie spatiale des réseaux, en développant des méthodes, des modèles et en les appliquant sur des données écologiques. La thèse s’articule autour de quatre chapitres. Dans un premier chapitre, on se penchera sur le problème de comparaison de réseau en différents points du temps et de l’espace. Nous étendrons les mesures de diversité, jusque-là développées pour des abondances uniquement, aux réseaux avec abondances des espèces et des interactions. Nous nous attacherons à définir des indices à plusieurs niveaux d’agrégation des noeuds dans le réseau et montrerons l’intérêt de la méthode sur des données de réseaux trophiques. Dans un deuxième chapitre, nous nous intéresserons au développement d’une théorie des méta-communautés qui modélise explicitement l’espace comme un réseau spatial et la communauté comme un réseau d’interaction. Nous définirons la notion de capacité de persistance de la méta-communauté. Dans un troisième chapitre, nous nous intéresserons aux problèmes d’inférence d’interactions sur des données de sol d’ADN environnemental le long d’un gradient d’altitude dans les Alpes. Nous montrerons que la méthode proposée permet d’estimer l’influence des variables environnementales et de reconstruire un réseau d'interaction cohérent vis-à-vis de la littérature. Dans un quatrième chapitre, nous nous intéresserons à la combinaison d’abondances provenant de différents marqueurs d’ADN environemental et montrerons l’efficacité de la méthode proposée pour obtenir des meilleurs données d’abondances sur des données de plantes<br>This thesis focuses on the links between interaction networks, space and time. There is a paradigm shift in community ecology concerning the representation of a species community : from a collection of species towards species and their interactions, represented by an interaction network. We aim to build the bricks for a spatial network theory, by developing new methods, new models and applying it on ecological data. This manuscript contains four chapters. In a first chapter, we extend the diversity indices, built on Hill numbers, to network diversity indices. We define diversity indices across species aggregation levelsand show the interest of this method on a trophic network data set. In a second chapter, we develop a spatially explicit meta-community theory, with various kind of interactions. The theory contains a stochastic and a deterministic meta-community model. We then define the notion of meta-community persistence capacity. In a third chapter, we focus on network reconstruction from environmental DNA data along an environmental gradient.We show that the proposed method allows to evaluate the influence of environmental variables on community and infer a network in agreement with the literature on soil interactions. Finally, in a fourth chapter, we develop a method to combine environmental DNA data coming from different primers and show the efficiency of the method to better estimate plant abundances

This project covers the methodology and process of landscape architectural design with emphasis on incorporating Function-based Habitat Design into conventional design processes. The Tshwane urban realm is characterised by the lack of wildlife habitat and serves as backdrop for the new design process demonstration. This new process aims to generate habitat for both humans and the natural ecology through a principled urban framework and ecological design. It creates the opportunity to enhance biodiversity throughout the city through interference on precinct, site and detailed level.<br>Dissertation (ML (Prof))--University of Pretoria, 2005.<br>Architecture<br>unrestricted

碩士<br>國立中山大學<br>應用數學系研究所<br>93<br>The Hill''s equation is the Schrodinger equation $$-y''+qy=la y$$ with a periodic one-dimensional potential function $q$ and coupled with periodic boundary conditions $y(0)=y(1)$, $y''(0)=y''(1)$ or anti-periodic boundary conditions $y(0)=-y(1)$, $y''(0)=-y''(1)$. We study the inverse nodal problem for Hill''s equation, in particular the reconstruction problem. Namely, we want to reconstruct the potential function using only nodal data ( zeros of eigenfunctions ). In this thesis, we give a reconstruction formula for $q$ using the periodic nodal data or using anti-periodic nodal data We show that the convergence is pointwise for all $x in (0,1)$ where $q$ is continuous; and pointwise for $a.e.$ $x in (0,1)$ as well as $L^1$ convergence when $qin L^1(0,1)$. We do this by making a translation so that the problem becomes a Dirichlet problem. The idea comes from the work of Coskun and Harris.