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Silva, Soto Daniel Alejandro. "Personalised finite-element models using image registration in parametric space." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/8584/.
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Heart failure (HF) is a chronic clinical condition in which the heart fails to pump enough blood to meet the metabolic needs of the body. Patients have reduced physical performance and can see their quality of life severely impaired; around 40-70% of patients diagnosed of HF die within the first year following diagnosis. It is underestimated that 900,000 people in the UK currently suffer from HF. HF has a big impact on the NHS, representing 1 million inpatient bed, 5% of all emergency medical admission to hospitals and costs 2% of the total NHS budget. The annual incidence of new diagnoses is reported as 93,000 people in England alone – and this figure is already increasing at a rate above that at which population is ageing [1]. Cardiac resynchronisation therapy (CRT) has become established as an effective solution to treat selected patients with HF. The research presented in this thesis has been conducted as part of a large EPSRC-Funded project on the theme of Grand Challenges in Heathcare, with co-investigators from King’s College London (KCL), Imperial College London, University College London (UCL) and the University of Sheffield. The aim is to develop and to apply modelling techniques to simulate ventricular mechanics and CRT therapy in patient cohorts from Guy’s Hospital (London) and from the Sheffield Teaching Hospitals Trust. This will lead to improved understanding of cardiac physiological behaviour and how diseases affect normal cardiac performance, and to improved therapy planning by allowing candidate interventions to be simulated before they are applied on patients. The clinical workflow within the hospital manages the patient through the processes of diagnosis, therapy planning and follow-up. The first part of this thesis focuses on the development of a formal process for the integration of a computational analysis workflow, including medical imaging, segmentation, model construction, model execution and analysis, into the clinical workflow. During the early stages of the project, as the analysis workflow was being compiled, a major bottle-neck was identified regarding the time required to build accurate, patient-specific geometrical meshes from the segmented images. The second part of this thesis focuses on the development of a novel approach based on the use of image registration to improve the process of construction of a high-quality personalised finite element mesh for an individual patient. Chapter 1 summarises the clinical context and introduces the tools and processes that are applied in this thesis. Chapter 2 describes the challenges and the implementation of a computational analysis workflow and its integration into a clinical environment. Chapter 3 describes the theoretical underpinnings of the image registration algorithm that has been developed to address the problem of construction of high-quality personalised meshes. The approach includes the use of regularisation terms that are designed to improve the mesh quality. The selection and implementation of the regularisation terms is discussed in detail in Chapter 4. Chapter 5 describes the application of the method to a series of test problems, whilst Chapter 6 describes the application to the patient cohort in the clinical study. Chapter 7 demonstrates that the method, developed for robust mesh construction, can readily be applied to determine boundary conditions for computational fluid dynamics (CFD) analysis. Chapter 8 provides a summary of the achievements of the thesis, together with suggestions for further work.
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Nikpour, Mehdi. "Toeplitzness of Composition Operators and Parametric Toeplitzness." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1346951238.
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BARROSO, VITOR BARATA RIBEIRO BLANCO. "EFFICIENT FLUID SIMULATION IN THE PARAMETRIC SPACE OF THREE-DIMENSIONAL STRUCTURED GRIDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=28689@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
BOLSA NOTA 10
Fluidos são extremamente comuns em nosso mundo e têm papel central em muitos fenômenos naturais. A compreensão de seu comportamento tem importância fundamental em uma vasta gama de aplicações e diversas áreas de pesquisa, da análise de fluxo sanguíneo até o transporte de petróleo, da exploração do fluxo de um rio até a previsão de maremotos, tempestades e furacões. Na simulação de fluidos, a abordagem conhecida como Euleriana é capaz de gerar resultados bastante corretos e precisos, mas as computações envolvidas podem se tornar excessivamente custosas quando há a necessidade de tratar fronteiras curvas e obstáculos com formas complexas. Este trabalho aborda esse problema e apresenta uma técnica Euleriana rápida e direta para simular o escoamento de fluidos em grades estruturadas parametrizadas tridimensionais. O principal objetivo do método é tratar de forma correta e eficiente as interações de fluidos com fronteiras curvas, incluindo paredes externas e obstáculos internos. Para isso, são utilizadas matrizes Jacobianas por célula para relacionar as derivadas de campos escalares e vetoriais nos espaços do mundo e paramétrico, o que permite a resolução das equações de Navier-Stokes diretamente no segundo, onde a discretização do domínio torna-se simplesmente uma grade uniforme. O trabalho parte de um simulador baseado em grades regulares e descreve como adaptá-lo com a aplicação das matrizes Jacobianas em cada passo, incluindo a resolução de equações de Poisson e dos sistemas lineares esparsos associados, utilizando tanto iterações de Jacobi quanto o método do Gradiente Biconjugado Estabilizado. A técnica é implementada na linguagem de programação CUDA e procura explorar ao máximo a arquitetura massivamente paralela das placas gráficas atuais.
Fluids are extremely common in our world and play a central role in many natural phenomena. Understanding their behavior is of great importance to a broad range of applications and several areas of research, from blood flow analysis to oil transportation, from the exploitation of river flows to the prediction of tidal waves, storms and hurricanes. When simulating fluids, the so-called Eulerian approach can generate quite correct and precise results, but the computations involved can become excessively expensive when curved boundaries and obstacles with complex shapes need to be taken into account. This work addresses this problem and presents a fast and straightforward Eulerian technique to simulate fluid flows in three-dimensional parameterized structured grids. The method s primary design goal is the correct and efficient handling of fluid interactions with curved boundary walls and internal obstacles. This is accomplished by the use of per-cell Jacobian matrices to relate field derivatives in the world and parameter spaces, which allows the Navier-Stokes equations to be solved directly in the latter, where the domain discretization becomes a simple uniform grid. The work builds on a regular-grid-based simulator and describes how to apply Jacobian matrices to each step, including the solution of Poisson equations and the related sparse linear systems using both Jacobi iterations and a Biconjugate Gradient Stabilized solver. The technique is implemented efficiently in the CUDA programming language and strives to take full advantage of the massively parallel architecture of today s graphics cards.
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Chau, Thi Tuyet Trang. "Non-parametric methodologies for reconstruction and estimation in nonlinear state-space models." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S010/document.
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Le volume des données disponibles permettant de décrire l’environnement, en particulier l’atmosphère et les océans, s’est accru à un rythme exponentiel. Ces données regroupent des observations et des sorties de modèles numériques. Les observations (satellite, in situ, etc.) sont généralement précises mais sujettes à des erreurs de mesure et disponibles avec un échantillonnage spatio-temporel irrégulier qui rend leur exploitation directe difficile. L’amélioration de la compréhension des processus physiques associée à la plus grande capacité des ordinateurs ont permis des avancées importantes dans la qualité des modèles numériques. Les solutions obtenues ne sont cependant pas encore de qualité suffisante pour certaines applications et ces méthodes demeurent lourdes à mettre en œuvre. Filtrage et lissage (les méthodes d’assimilation de données séquentielles en pratique) sont développés pour abonder ces problèmes. Ils sont généralement formalisées sous la forme d’un modèle espace-état, dans lequel on distingue le modèle dynamique qui décrit l’évolution du processus physique (état), et le modèle d’observation qui décrit le lien entre le processus physique et les observations disponibles. Dans cette thèse, nous abordons trois problèmes liés à l’inférence statistique pour les modèles espace-états: reconstruction de l’état, estimation des paramètres et remplacement du modèle dynamique par un émulateur construit à partir de données. Pour le premier problème, nous introduirons tout d’abord un algorithme de lissage original qui combine les algorithmes Conditional Particle Filter (CPF) et Backward Simulation (BS). Cet algorithme CPF-BS permet une exploration efficace de l’état de la variable physique, en raffinant séquentiellement l’exploration autour des trajectoires qui respectent le mieux les contraintes du modèle dynamique et des observations. Nous montrerons sur plusieurs modèles jouets que, à temps de calcul égal, l’algorithme CPF-BS donne de meilleurs résultats que les autres CPF et l’algorithme EnKS stochastique qui est couramment utilisé dans les applications opérationnelles. Nous aborderons ensuite le problème de l’estimation des paramètres inconnus dans les modèles espace-état. L’algorithme le plus usuel en statistique pour estimer les paramètres d’un modèle espace-état est l’algorithme EM qui permet de calculer itérativement une approximation numérique des estimateurs du maximum de vraisemblance. Nous montrerons que les algorithmes EM et CPF-BS peuvent être combinés efficacement pour estimer les paramètres d’un modèle jouet. Pour certaines applications, le modèle dynamique est inconnu ou très coûteux à résoudre numériquement mais des observations ou des simulations sont disponibles. Il est alors possible de reconstruire l’état conditionnellement aux observations en utilisant des algorithmes de filtrage/lissage dans lesquels le modèle dynamique est remplacé par un émulateur statistique construit à partir des observations. Nous montrerons que les algorithmes EM et CPF-BS peuvent être adaptés dans ce cadre et permettent d’estimer de manière non-paramétrique le modèle dynamique de l’état à partir d'observations bruitées. Pour certaines applications, le modèle dynamique est inconnu ou très coûteux à résoudre numériquement mais des observations ou des simulations sont disponibles. Il est alors possible de reconstruire l’état conditionnellement aux observations en utilisant des algorithmes de filtrage/lissage dans lesquels le modèle dynamique est remplacé par un émulateur statistique construit à partir des observations. Nous montrerons que les algorithmes EM et CPF-BS peuvent être adaptés dans ce cadre et permettent d’estimer de manière non-paramétrique le modèle dynamique de l’état à partir d'observations bruitées. Enfin, les algorithmes proposés sont appliqués pour imputer les données de vent (produit par Météo France)The amount of both observational and model-simulated data within the environmental, climate and ocean sciences has grown at an accelerating rate. Observational (e.g. satellite, in-situ...) data are generally accurate but still subject to observational errors and available with a complicated spatio-temporal sampling. Increasing computer power and understandings of physical processes have permitted to advance in models accuracy and resolution but purely model driven solutions may still not be accurate enough. Filtering and smoothing (or sequential data assimilation methods) have developed to tackle the issues. Their contexts are usually formalized under the form of a space-state model including the dynamical model which describes the evolution of the physical process (state), and the observation model which describes the link between the physical process and the available observations. In this thesis, we tackle three problems related to statistical inference for nonlinear state-space models: state reconstruction, parameter estimation and replacement of the dynamic model by an emulator constructed from data. For the first problem, we will introduce an original smoothing algorithm which combines the Conditional Particle Filter (CPF) and Backward Simulation (BS) algorithms. This CPF-BS algorithm allows for efficient exploration of the state of the physical variable, sequentially refining exploration around trajectories which best meet the constraints of the dynamic model and observations. We will show on several toy models that, at the same computation time, the CPF-BS algorithm gives better results than the other CPF algorithms and the stochastic EnKS algorithm which is commonly used in real applications. We will then discuss the problem of estimating unknown parameters in state-space models. The most common statistical algorithm for estimating the parameters of a space-state model is based on EM algorithm, which makes it possible to iteratively compute a numerical approximation of the maximum likelihood estimators. We will show that the EM and CPF-BS algorithms can be combined to effectively estimate the parameters in toy models. In some applications, the dynamical model is unknown or very expensive to solve numerically but observations or simulations are available. It is thence possible to reconstruct the state conditionally to the observations by using filtering/smoothing algorithms in which the dynamical model is replaced by a statistical emulator constructed from the observations. We will show that the EM and CPF-BS algorithms can be adapted in this framework and allow to provide non-parametric estimation of the dynamic model of the state from noisy observations. Finally the proposed algorithms are applied to impute wind data (produced by Méteo France)
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Lim, Ryan S. (Ryan Seungwook). "Staged attitude-metrology pointing control and parametric integrated modeling for space-based optical systems." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35574.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 155-158).
The quest for higher sensitivity and finer angular resolution in astronomy demands larger and more complex space imaging systems. This thesis presents the concepts developed for two different technologies that have the potential to contribute in improving the performance of space imaging systems. The first technology is precision pointing control technology, which can provide fine optical control operating in conjunction with coarse formation flying attitude control in order to meet the stringent optical requirements. This will potentially enable a long baseline Formation Flying Interferometer (FFI) such as NASA's Terrestrial Planet Finder (TPF). The concept for precision pointing control was realized by a testbed called the Precision Pointing Optical Payload (PPOP). The design and implementation of the PPOP are described, followed by an experimental demonstration of staged pointing control. The global metrology system of the Synchronized Position Hold Engage Reorient Experimental Satellites (SPHERES) provides coarse attitude control, whereas the PPOP provides fine pointing control using a set of fast steering mirrors. The second technology investigates parametric integrated modeling of space telescopes.
(cont.) This technology provides a design tool for examining alternative telescope architectures and identifying favorable architectures at an early stage of the design lifecycle. The MIT Space Systems Laboratory (MIT-SSL) is currently developing a parametric integrated model for a Modular Optical Space Telescope (MOST). This thesis provides an overview of the MOST model, with emphasis on the development of the optics sub-model. ZEMAX is used for calculating the wave front error based on the Zernike sensitivity analysis. A data interface between ZEMAX and MATLAB has been developed, which makes the process of performing the Zernike sensitivity analysis automated.
by Ryan S. Lim.
S.M.
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Martens, Bas. "A fluid loop actuator for active spacecraft attitude control - A Parametric Sizing Model and the Design, Verification, Validation and Test with a Prototype on an Air Bearing." Master's thesis, Faculty of Engineering and the Built Environment, 2019. https://hdl.handle.net/11427/31621.
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Active spacecraft attitude control by using a pumped fluid as the inertial mass has potential advantages over reaction wheels, including high torque, lower power consumption, reduced jitter and prolonged lifetime. Previous work addressed conceptual and mission-specific control aspects, and one fluid loop has flown on a demonstration mission. In this dissertation, a parametric sizing model is developed that can optimize a fluid loop for any mission, based on pump capabilities and customer requirements. The model can be applied to circular, square and helical fluid loops, and includes the power consumption due to viscous friction. A configurable prototype was developed to verify the model, as well as a spherical air bearing to verify the rotational aspects of the various fluid loop configurations. The model was applied to various hypothetical missions. In conclusion, the fluid loop has the fundamental potential to replace reaction wheels in a wide variety of satellites above approximately 20 kg, if mass is carefully optimized and efforts are made to develop a suitable pump. This is considered worthwhile, as the actuator comes with many potential advantages.
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Gao, Haotian. "POD-Galerkin based ROM for fluid flow with moving boundaries and the model adaptation in parametric space." Diss., Kansas State University, 2018. http://hdl.handle.net/2097/38776.
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Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Mingjun Wei
In this study, a global Proper Orthogonal Decomposition (POD)-Galerkin based Reduced Order model (ROM) is proposed. It is extended from usual fixed-domain problems to more general fluid-solid systems with moving boundaries/interfaces. The idea of the extension is similar to the immersed boundary method in numerical simulations which uses embedded forcing terms to represent boundary motions and domain changes. This immersed boundary method allows a globally defined fixed domain including both fluid and solid, where POD-Galerkin projection can be directly applied. However, such a modified approach cannot get away with the unsteadiness of boundary terms which appear as time-dependent coefficients in the new Galerkin model. These coefficients need to be pre-computed for prescribed periodic motion, or worse, to be computed at each time step for non-prescribed (e.g. with fluid-structure interaction) or non-periodic situations. Though computational time for each unsteady coefficient is smaller than the coefficients in a typical Galerkin model, because the associated integration is only in the close neighborhood of moving boundaries. The time cost is still much higher than a typical Galerkin model with constant coefficients. This extra expense for moving-boundary treatment eventually undermines the value of using ROMs. An aggressive approach is to decompose the moving boundary/domain to orthogonal modes and derive another low-order model with fixed coefficients for boundary motion. With this domain decomposition, an approach including two coupled low-order models both with fixed coefficients is proposed. Therefore, the new global ROM with decomposed approach is more efficient. Though the model with the domain decomposition is less accurate at the boundary, it is a fair trade-off for the benefit on saving computational cost. The study further shows, however, that the most time-consuming integration in both approaches, which come from the unsteady motion, has almost negligible impact on the overall dynamics. Dropping these time-consuming terms reduces the computation cost by at least one order while having no obvious effect on model accuracy. Based on this global POD-Galerkin based ROM with forcing term, an improved ROM which can handle the parametric variation of body motions in a certain range is also presented. This study shows that these forcing terms not only represent the moving of the boundary, but also decouple the moving parameters from the computation of model coefficients. The decoupling of control parameters provides the convenience to adapt the model for the prediction on states under variation of control parameters. An improved ROM including a shit mode seems promising in model adaptation for typical problems in a fixed domain. However, the benefit from adding a shit mode to model diminishes when the method is applied to moving-boundary problems. Instead, a combined model, which integrates data from a different set of parameters to generate the POD modes, provides a stable and accurate ROM in a certain range of parametric space for moving-boundary problems. By introducing more data from a different set of parameters, the error of the new model can be further reduced. This shows that the combined model can be trained by introducing more and more information. With the idea of the combined model, the improved global ROM with forcing terms shows impressive capability to predict problems with different unknown moving parameters, and can be used in future parametric control and optimization problems.
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Larson, Brady M. "Exploring the Common Design Space of Dissimilar Assembly Parameterizations for Interdisciplinary Design." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2368.pdf.
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Wellstead, Kevin. "Robust polynomial controller design." Thesis, Brunel University, 1991. http://bura.brunel.ac.uk/handle/2438/4866.
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The work presented in this thesis was motivated by the desire to establish an alternative approach to the design of robust polynomial controllers. The procedure of pole-placement forms the basis of the design and for polynomial systems this generally involves the solution of a diophantine equation. This equation has many possible solutions which leads directly to the idea of determining the most appropriate solution for improved performance robustness. A thorough review of many of the aspects of the diophantine equation is presented, which helps to gain an understanding of this extremely important equation. A basic investigation into selecting a more robust solution is carried out but it is shown that, in the polynomial framework, it is difficult to relate decisions in the design procedure to the effect on performance robustness. This leads to the approach of using a state space based design and transforming the resulting output feedback controller to polynomial form. The state space design is centred around parametric output feedback which explicitly represents a set of possible feedback controllers in terms of arbitrary free parameters. The aim is then to select these free parameters such that the closed-loop system has improved performance robustness. Two parametric methods are considered and compared, one being well established and the other a recently proposed scheme. Although the well established method performs slightly better for general systems it is shown to fail when applied to this type of problem. For performance robustness, the shape of the transient response in the presence of model uncertainty is of interest. It is well known that the eigenvalues and eigenvectors play an important role in determining the transient behaviour and as such the sensitivities of these factors to model uncertainty forms the basis on which the free parameters are selected. Numerical optimisation is used to select the free parameters such that the sensitivities are at a minimum. It is shown both in a simple example and in a more realistic application that a significant improvement in the transient behaviour in the presence of model uncertainty can be achieved using the proposed design procedure.
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Patil, Aniket, and Girish Chebbi. "Exploring the design space of aluminium tubing using knowledge objects and FEM." Thesis, Jönköping University, JTH, Mechanical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-9074.
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Bordikar, Maitrayee Ranade. "Analysis of Plasma Wave Irregularities Generated during Active Experiments in Near-Earth Space Environment." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23206.
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This work focuses on the analysis of plasma irregularities generated during two active space experiments: the injection of an artificial dust layer, and high-power radio waves. The objective of the "first experiment is to examine the effects of artificially created dust layers on the scatter of radars from plasma irregularities embedded in dusty plasma in space. This is an alternate approach for understanding the mechanisms of enhanced radar scatter from plasma irregularities embedded in Noctilucent Clouds and Polar Mesospheric Summer Echoes. The second experiment involves a transmission of high power electromagnetic waves into the ionospheric plasma from the ground, which can excite stimulated electromagnetic emissions offset from the transmitter frequency. These stimulated electromagnetic emissions provide diagnostic information of the ionosphere and thus can be used to investigate fundamental physical principles which govern the earth\'s ionosphere, so that present and future transmission technologies may take into account the complexities of the ionosphere. The interaction altitude of the artificial dust layer and high power radio waves is approximately 250 km and 160 km respectively, thus dealing with uniquely different regions of the ionosphere. Each experiment is discussed separately using theoretical, observational and advanced computational methodologies.
The study first investigates plasma turbulence associated with the creation of an artificial dust layer in the earth's ionosphere. Two scenarios are considered for plasma irregularity generation as dust is injected at an oblique angle across the geomagnetic field. The first is a shear-driven plasma instability due to inhomogeneities in the boundary layer between the injected charged dust layer and the background plasma. This begins to appear at very early times once the dust is released into the space plasma, which is of the order or less than the dust charging time period. The second mechanism is free streaming of the charged dust relative to the background plasma. This produces irregularities at times much longer than the dust charging period and also longer than the dust plasma period. Although both mechanisms are shown to produce turbulence in the lower hybrid frequency range, the resulting irregularities have important differences in their physical characteristics. A comparison between the processes is made to determine the consequences for upcoming observations. Both processes are shown to have the possibility of generating turbulence after the release of dust for the regimes of upcoming space experiments over a range of timescales.
This work also presents the first observations of unique narrowband emissions ordered near the Hydrogen ion (H+) gyro-frequency (fcH) in the Stimulated Electromagnetic Emission (SEE) spectrum when the transmitter is tuned near the second electron gyro-harmonic frequency (2fce), during ionospheric modification experiments. The frequency structuring of these newly discovered emission lines is quite unexpected since H+ is known to be a minor constituent in the interaction region which is near 160 km altitude. The spectral lines are typically shifted from the pump wave frequency by harmonics of a frequency about 10% less than fcH (" 800 Hz) and have a bandwidth of less than 50 Hz which is near the O+ gyro-frequency fcO. A theory is proposed to explain these emissions in terms of a Parametric Decay Instability (PDI) in a multi-ion species plasma due to possible proton precipitation associated with the disturbed conditions during the heating experiment. The observations can be explained by including several percent H+ ions into the background plasma. The implications are new possibilities for characterizing proton precipitation events during ionospheric heating experiments.Ph. D.
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Nikbakht, Silab Rasoul. "Unsupervised learning for parametric optimization in wireless networks." Doctoral thesis, Universitat Pompeu Fabra, 2021. http://hdl.handle.net/10803/671246.
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This thesis studies parametric optimization in cellular and cell-free networks, exploring data-based and expert-based paradigms. Power allocation and power control, which adjust the transmit power to meet different fairness criteria such as max-min or max-product, are crucial tasks in wireless communications that fall into the parametric optimization category. The state-of-the-art approaches for power control and power allocation often demand huge computational costs and are not suitable for real-time applications. To address this issue, we develop a general-purpose unsupervised-learning approach for solving parametric optimizations; and extend the well-known fractional power control algorithm.
In the data-based paradigm, we create an unsupervised learning framework that defines a custom neural network (NN), incorporating expert knowledge to the NN loss function to solve the power control and power allocation problems. In this approach, a feedforward NN is trained by repeatedly sampling the parameter space, but, rather than solving the associated optimization problem completely, a single step is taken along the gradient of the objective function. The resulting method is applicable for both convex and non-convex optimization problems. It offers two-to-three orders of magnitude speedup in the power control and power allocation problems compared to a convex solver—whenever appliable.
In the expert-driven paradigm, we investigate the extension of fractional power control to cell-free networks. The resulting closed-form solution can be evaluated for uplink and downlink effortlessly and reaches an (almost) optimum solution in the uplink case.
In both paradigms, we place a particular focus on large scale gains—the amount of attenuation experienced by the local-average received power. The slow-varying nature of the large-scale gains relaxes the need for a frequent update of the solutions in both the data-driven and expert-driven paradigms, enabling real-time application for both methods.Aqueta tesis estudia l’optimització paramètrica a les xarxes cel.lulars i xarxes cell-free, explotant els paradigmes basats en dades i basats en experts. L’assignació i control de la potencia, que ajusten la potencia de transmissió per complir amb diferents criteris d’equitat com max-min o max-product, son tasques crucials en les telecomunicacions inalàmbriques pertanyents a la categoria d’optimització paramètrica. Les tècniques d’última generació per al control i assignació de la potència solen exigir enormes costos computacionals i no son adequats per aplicacions en temps real. Per abordar aquesta qüestió, desenvolupem una tècnica de propòsit general utilitzant aprenentatge no supervisat per resoldre optimitzacions paramètriques; i al mateix temps ampliem el reconegut algoritme de control de potencia fraccionada. En el paradigma basat en dades, creem un marc d’aprenentatge no supervisat que defineix una xarxa neuronal (NN, sigles de Neural Network en Anglès) especifica, incorporant coneixements experts a la funció de cost de la NN per resoldre els problemes de control i assignació de potència. Dins d’aquest enfocament, s’entrena una NN de tipus feedforward mitjançant el mostreig repetit en l’espai de paràmetres, però, en lloc de resoldre completament el problema d’optimització associat, es pren un sol pas en la direcció del gradient de la funció objectiu. El mètode resultant ´es aplicable tant als problemes d’optimització convexos com no convexos. Això ofereix una acceleració de dos a tres ordres de magnitud en els problemes de control i assignació de potencia en comparació amb un algoritme de resolució convexa—sempre que sigui aplicable. En el paradigma dirigit per experts, investiguem l’extensió del control de potencia fraccionada a les xarxes sense cèl·lules. La solució tancada resultant pot ser avaluada per a l’enllaç de pujada i el de baixada sense esforç i assoleix una solució (gaire) òptima en el cas de l’enllaç de pujada. En ambdós paradigmes, ens centrem especialment en els guanys a gran escala—la quantitat d’atenuació que experimenta la potencia mitja local rebuda. La naturalesa de variació lenta dels guanys a gran escala relaxa la necessitat d’una actualització freqüent de les solucions tant en el paradigma basat en dades com en el basat en experts, permetent d’aquesta manera l’ús dels dos mètodes en aplicacions en temps real.
Esta tesis estudia la optimización paramétrica en las redes celulares y redes cell-free, explorando los paradigmas basados en datos y en expertos. La asignación y el control de la potencia, que ajustan la potencia de transmisión para cumplir con diferentes criterios de equidad como max-min o max-product, son tareas cruciales en las comunicaciones inalámbricas pertenecientes a la categoría de optimización paramétrica. Los enfoques más modernos de control y asignación de la potencia suelen exigir enormes costes computacionales y no son adecuados para aplicaciones en tiempo real. Para abordar esta cuestión, desarrollamos un enfoque de aprendizaje no supervisado de propósito general que resuelve las optimizaciones paramétricas y a su vez ampliamos el reconocido algoritmo de control de potencia fraccionada. En el paradigma basado en datos, creamos un marco de aprendizaje no supervisado que define una red neuronal (NN, por sus siglas en inglés) específica, incorporando conocimiento de expertos a la función de coste de la NN para resolver los problemas de control y asignación de potencia. Dentro de este enfoque, se entrena una NN de tipo feedforward mediante el muestreo repetido del espacio de parámetros, pero, en lugar de resolver completamente el problema de optimización asociado, se toma un solo paso en la dirección del gradiente de la función objetivo. El método resultante es aplicable tanto a los problemas de optimización convexos como no convexos. Ofrece una aceleración de dos a tres órdenes de magnitud en los problemas de control y asignación de potencia, en comparación con un algoritmo de resolución convexo—siempre que sea aplicable. Dentro del paradigma dirigido por expertos, investigamos la extensión del control de potencia fraccionada a las redes cell-free. La solución de forma cerrada resultante puede ser evaluada para el enlace uplink y el downlink sin esfuerzo y alcanza una solución (casi) óptima en el caso del enlace uplink. En ambos paradigmas, nos centramos especialmente en las large-scale gains— la cantidad de atenuación que experimenta la potencia media local recibida. La naturaleza lenta y variable de las ganancias a gran escala relaja la necesidad de una actualización frecuente de las soluciones tanto en el paradigma basado en datos como en el basado en expertos, permitiendo el uso de ambos métodos en aplicaciones en tiempo real.
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Gim, Suhyeon. "Flexible and Smooth Trajectory Generation based on Parametric Clothoids for Nonholonomic Car-like Vehicles." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC023/document.
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La génération de chemins lisses pour les voitures intelligentes est l’une des conditions les plus importantes pour faire accepter et faciliter la navigation autonome de ces véhicules. Cette thèse propose plusieurs méthodes de génération de chemins lisses pour les véhicules non-holonomes qui permet une continuité intrinsèque de la courbure de navigation et offre par ailleurs une flexibilité accrue pour diverses conditions aux limites. Le chemin de courbure continue est construit en composant plusieurs clothoids, comprenant notamment des segments de lignes et/ou d’arcs, et où chaque clothoid est obtenue par une régulation appropriée de ses paramètres. À partir de ces propriétés, le chemin obtenu est nommé pCCP (parametric Continuous Curvature Path). Le pCCP fournit un diagramme de courbure qui facilite une commande en orientation du véhicule, ce qui permet d'obtenir une évolution lisse de sa trajectoire. Le problème du pCCP local est défini par des configurations initiales et finales (caractérisées pour chacune par une posture et un angle de braquage). Le problème a été étendu pour être aussi général que possible en incluant plusieurs cas. La génération locale de pCCPs, pour des cibles statiques, est spécifiquement décrite, les problèmes ont été divisés en trois problèmes et chaque problème a été décomposé par la suite en plusieurs sous-classes possibles. Pour avoir une flexibilité importante des pCCPs proposés, des cibles dynamiques ont été considérées, obtenant ainsi le dynamic-pCCP (d-pCCP). Un cadre simple mais efficace pour analyser l'état futur de l'évitement des obstacles est appliqué en configuration 4D (3D avec l’ajout d’un axe temporel) en mettant en exergue deux manoeuvres d’évitement possibles, car les évolutions avant et arrière sont appliquées et validées avec plusieurs exemples. Selon une méthodologie similaire pour atteindre les critères de performance liés à la génération des pCCPs, le h-CCP (pour human-pCCP) est proposé en utilisant des modèles expérimentaux comportementaux d’échantillons de conducteurs humains. À partir de quelques sous-expériences, le modèle de conduite humain pour l’évitement d’obstacles, les changements de voie et les mouvements en virage sont extraits et ces modèles ont été inclus pour créer ainsi le h-CCP (obtenu d’une manière similaire au pCCP mais avec différents critères d’optimisation) qui permet d’améliorer considérablement le confort des passagersSmooth path generation for car-like vehicles is one of the most important requisite to facilitate the broadcast use of autonomous navigation. This thesis proposes a smooth path generation method for nonholonomic vehicles which has inherently continuity of curvature and having important flexibility for various boundary conditions. The continuous curvature path is constructed by composing multiple clothoids including lines and/or arc segments, and where each clothoid is obtained by parameter regulation. From those properties the path is named pCCP (parametric Continuous Curvature Path) and provides curvature diagram which facilitates a smooth steering control for path following problem. Local pCCP problem is defined by initial and final tuple configurations (vehicles posture and steering angle). The problem is expanded to be as general as possible by including several cases. The local pCCP generation for steady target pose is specifically described, where the problem is divided into three problems and each problem is also decomposed into several sub-cases. To give more flexibility to the proposed pCCP, dynamic target is considered to obtain dynamic-pCCP (d-CCP). A simple but efficient framework to analyze the future status of obstacle avoidance is applied in 4D (3D with the addition of time axis) configuration and two avoidance maneuvers as front and rear avoidance are applied and validated with several examples. Under the similar methodology in performance criteria of pCCP generation, the human-CCP (h-CCP) is derived from experimental patterns of human driver samples. From several subexperiments, human driving pattern for obstacle avoidance, lane change and cornering motion are extracted and those pattern were included to make the h-CCP (which is obtained with similar way as pCCP but with different optimization criteria) to enhance considerably the passenger comfort
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Cardoso, Cilene Estol. "Desenvolvimento de um método de controle de distorções para aplicação em problemas de design de superfície de formas tridimensionais não planificáveis." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18604.
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Este trabalho tem por objetivo desenvolver um método de controle de distorção adequado ao design de superfície de produto industrial, com forma tridimensional não planificável, produzido em larga escala, de modo a minimizar as distorções gráficas procedentes da aplicação de uma imagem bidimensional em um objeto tridimensional com superfície não planificável, considerando, principalmente, a complexidade da geometria do objeto. Essa pesquisa justifica-se quando se verifica o aumento de produtos com formas não planificáveis no mercado e a visível dificuldade dos profissionais em resolver problemas de distorções das imagens quando o objeto tem uma geometria complexa. Além disso, o estudo visa contribuir também com a redução de custos de desenvolvimento desse tipo de produto, já que estuda um método que possibilita a verificação digital, eliminando os custos físicos de tentativa e erro. O método utiliza recursos de representação paramétrica de superfícies, que viabilizam a manipulação de objetos tridimensionais complexos no meio computacional e que são definidos por equações que relacionam um domínio paramétrico plano e o espaço tridimensional. Para cada uma das dimensões (x, y e z) do espaço tridimensional, existe uma equação que faz a relação com o espaço paramétrico bidimensional de coordenadas u e v. Dentre esses recursos, os mais utilizados são: mapeamento de textura e render to texture. A indústria de desenhos animados e games tridimensionais costuma utilizar com frequência estes recursos computacionais para melhorar o realismo de suas imagens. Nesta pesquisa, estudase a possibilidade de direcionar essas ferramentas computacionais para a indústria de produtos físicos manufaturados produzidos em série. A pesquisa propõe-se estudar três casos de produtos com superfícies não planificáveis de materiais distintos e processos de produção diferentes entre si. A partir dos três estudos de casos é proposto o método que visa permitir a solução sistematizada dessa classe de problema relacionado às distorções. A verificação do método é realizada, com resultados significativos, em conjunto com três grandes empresas nacionais localizadas da região sul do Brasil. O primeiro estudo de caso consiste em uma tigela de cerâmica da empresa Oxford®; o segundo, uma chaleira de metal da empresa Tramontina®, e o terceiro, uma sandália de polímero da empresa Grendene®. Assim, por meio desta pesquisa, espera-se ampliar a área do conhecimento que circunscreve o design de superfície, ampliando os meios que facilitem a atividade projetual e apontando para a necessidade de instrumentos tecnológicos que venham facilitar os projetos de superfícies de objetos com formas não planificáveis.This work aims to develop a distortion control method adequate for surface design of mass-produced industrial products with non-planable tridimensional shape, so as to minimize the graphic distortions resulting from the application of a bidimensional image onto a tridimensional object with non-planable surface, taking into consideration mainly the complexity of the object’s geometry. The justification for this research lies in the increase of products with nonplanable shapes available on the market and in the clear difficulty of professionals to solve image distortion problems when the object presents complex geometry. Besides, this research aims to contribute to the reduction of costs of developing this kind of product, seeing that it studies a method that enables digital verification so eliminating the physical costs of trial and error. The method uses resources of parametric representation of surfaces, which enable the manipulation of complex 3D objects in the computational environment, and which are defined by equations that relate one plane parametric domain and the tridimensional space. For each dimension (x, y e z) of the tridimensional space there is an equation that makes the relation with the bidimensional parametric space with coordinates u and v. The most frequently used computational resources are texture mapping and render to texture, which are often used by the industry of 3-D animation to improve the realism of their images. In this work we study the possibility to apply these computational tools in the industry of manufactured products. This research contemplates three case studies of products with non-planable surfaces of different materials and different manufacturing processes. We then propose a method that allows a systematized solution for distortion-related problems. The verification of the method, which showed meaningful results, was carried out together with three large national enterprises located in the southern region of Brazil. The first case study consists in a ceramic bowl by Oxford®; the second, a metal kettle by Tramontina®; and the third, a polymer sandal by Grendene®. With this research we expect to expand the field of knowledge in which surface design is inserted thus extending the resources for the projectual activity and pointing to the need for technological tools that may help with the projects of surfaces of objects with non-planable shape.
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Norin, Lars. "Secondary Electromagnetic Radiation Generated by HF Pumping of the Ionosphere." Doctoral thesis, Uppsala universitet, Astronomi och rymdfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9393.
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Electromagnetic waves can be used to transmit information over long distances and are therefore often employed for communication purposes. The electromagnetic waves are reflected off material objects on their paths and interact with the medium through which they propagate. For instance, the plasma in the ionosphere can refract and even reflect radio waves propagating through it. By increasing the power of radio waves injected into the ionosphere, the waves start to modify the plasma, resulting in the generation of a wide range of nonlinear processes, including turbulence, in particular near the reflection region. By systematically varying the injected radio waves in terms of frequency, power, polarisation, duty cycle, inclination, etc. the ionosphere can be used as an outdoor laboratory for investigating fundamental properties of the near-Earth space environment as well as of plasma turbulence. In such ionospheric modification experiments, it has been discovered that the irradiation of the ionosphere by powerful radio waves leads to the formation of plasma density structures and to the emission of secondary electromagnetic radiation, a phenomenon known as stimulated electromagnetic emission. These processes are highly repeatable and have enabled systematic investigations of the nonlinear properties of the ionospheric plasma. In this thesis we investigate features of the plasma density structures and the secondary electromagnetic radiation. In a theoretical study we analyse a certain aspect of the formation of the plasma structures. The transient dynamics of the secondary radiation is investigated experimentally in a series of papers, focussing on the initial stage as well as on the decay. In one of the papers we use the transient dynamics of the secondary radiation to reveal the intimate relation between certain features of the radiation and structures of certain scales. Further, we present measurements of unprecedentedly strong secondary radiation, attributed to stimulated Brillouin scattering, and report measurements of the secondary radiation using a novel technique imposed on the transmitted radio waves.
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Aoun, Nadine. "Modeling and flexible predictive control of buildings space-heating demand in district heating systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC104.
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La gestion de la demande en chauffage des bâtiments raccordés à des réseaux de chaleur s'effectue classiquement au moyen d’une courbe de chauffe : lorsque la température extérieure chute, la température de départ de l’eau alimentant le circuit de chauffage interne est relevée. Ce mode de contrôle, appelé régulation par loi d’eau, présente des atouts en termes de simplicité et de robustesse, mais ne tient pas compte de l'inertie thermique du bâtiment et ne permet donc pas une modulation de sa demande. La modulation de la demande en chauffage se définit comme l'action de contrôle consistant à modifier de manière stratégique les conditions de confort thermique dans le cadre d’une optimisation énergétique et/ou économique. Il s’agit d’une brique essentielle du contrôle flexible qui envisage le déplacement des charges et l’effacement des pics pour une meilleure efficacité de production favorisant la pénétration des énergies renouvelables et de récupération.Ces travaux de thèse visent à développer une stratégie de contrôle prédictif et flexible de la demande en chauffage, applicable à grande échelle dans les réseaux de chaleur.Tout d'abord, un simulateur thermique dynamique de bâtiment résidentiel, équipé de radiateurs hydrauliques connectés à une sous-station de réseau de chaleur, est développé. Il permet de définir plusieurs cas d’études de bâtiments représentatifs du parc résidentiel français et constitue l’environnement expérimental virtuel de nos travaux de recherche. Ensuite, une méthodologie permettant d’obtenir un modèle orienté-contrôle et d’ordre réduit de bâtiment avec son système de chauffage est proposée. Elle commence par la définition de la structure du modèle en se basant sur des connaissances physiques, puis consiste en l'identification des paramètres par optimisation méta-heuristique à l'aide des données générées par le simulateur. L'approche d'identification paramétrique évalue la possibilité de réaliser cette tâche en ne s’appuyant que sur des données disponibles au niveau de la sous-station, notamment en s’interdisant d’utiliser des mesures de température intérieure au bâtiment, donnée à caractère personnel présumée indisponible à grande échelle pour des raisons techniques, économiques et juridiques. Enfin, la stratégie de contrôle prédictif est implémentée. Elle permet la planification de la température de départ de l'eau de chauffage en fonction des prévisions météorologiques et des prix de l’énergie. Le contrôleur flexible s’appuie sur un problème d’optimisation linéaire sous contraintes, selon le principe de l’horizon fuyant. Il incorpore les équations linéarisées du modèle d’ordre réduit et calcule le compromis optimal entre coûts énergétiques et inconfort thermique, le degré de flexibilité de la demande en chauffage étant défini par l’intermédiaire de paramètres de réglage dédiésIn District Heating Systems (DHSs), buildings Space-Heating (SH) demand management conventionally relies on a heating curve: when the outdoor temperature drops, the internal SH system supply water temperature is raised. This control mode, referred to as Weather-Compensation Control (WCC), offers widely recognized assets in terms of simplicity and robustness. However, WCC does not account for the building thermal inertia, and consequently, it does not allow modulation of its demand. SH demand modulation is the control action of strategically altering the indoor thermal comfort conditions within an energetic and/or economic optimization framework. It is a key measure in flexible demand control strategies, which seek loads shifting and peaks shaving to allow sustainable commitment of energy resources in favour of renewable power penetration and waste heat recovery.The work presented in this thesis aims at developing a flexible Model Predictive Control (MPC) strategy for SH demand, applicable at large scale in DHSs.Firstly, a thermal dynamic simulator of a residential building with a radiator SH circuit connected to a DHS substation is developed. It allows the definition of multiple case study buildings, well-representative of the french residential stock, and constitutes the virtual experimental environment for our research. Then, a methodology to obtain a control-oriented Reduced-Order Model (ROM) for the building and its SH system is proposed. It starts by defining the ROM structure based on physical knowledge, and proceeds to parameters identification by meta-heuristic optimization using data generated by the simulator. The parametric identification approach evaluates the possibility of carrying out this task by relying solely on data available at the substation level, refraining from using indoor temperature measurements, personal data assumed to be unavailable at large scale for technical, economic and legal reasons. Finally, MPC is implemented to schedule the SH supply water temperature as function of weather forecasts and energy price variations. The flexible controller is designed to solve a constrained linear optimization problem according to the receding horizon principle. It embeds the linearized ROM equations within the problem formulation and makes an optimal trade-off between energy consumption costs and thermal discomfort, the degree of flexibility to modulate SH demand being defined through dedicated tuning parameters
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Brooks, Alex. "Parametric POMDPs for planning in continuous state spaces." University of Sydney, 2007. http://hdl.handle.net/2123/1861.
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PhDThis thesis is concerned with planning and acting under uncertainty in partially-observable continuous domains. In particular, it focusses on the problem of mobile robot navigation given a known map. The dominant paradigm for robot localisation is to use Bayesian estimation to maintain a probability distribution over possible robot poses. In contrast, control algorithms often base their decisions on the assumption that a single state, such as the mode of this distribution, is correct. In scenarios involving significant uncertainty, this can lead to serious control errors. It is generally agreed that the reliability of navigation in uncertain environments would be greatly improved by the ability to consider the entire distribution when acting, rather than the single most likely state. The framework adopted in this thesis for modelling navigation problems mathematically is the Partially Observable Markov Decision Process (POMDP). An exact solution to a POMDP problem provides the optimal balance between reward-seeking behaviour and information-seeking behaviour, in the presence of sensor and actuation noise. Unfortunately, previous exact and approximate solution methods have had difficulty scaling to real applications. The contribution of this thesis is the formulation of an approach to planning in the space of continuous parameterised approximations to probability distributions. Theoretical and practical results are presented which show that, when compared with similar methods from the literature, this approach is capable of scaling to larger and more realistic problems. In order to apply the solution algorithm to real-world problems, a number of novel improvements are proposed. Specifically, Monte Carlo methods are employed to estimate distributions over future parameterised beliefs, improving planning accuracy without a loss of efficiency. Conditional independence assumptions are exploited to simplify the problem, reducing computational requirements. Scalability is further increased by focussing computation on likely beliefs, using metric indexing structures for efficient function approximation. Local online planning is incorporated to assist global offline planning, allowing the precision of the latter to be decreased without adversely affecting solution quality. Finally, the algorithm is implemented and demonstrated during real-time control of a mobile robot in a challenging navigation task. We argue that this task is substantially more challenging and realistic than previous problems to which POMDP solution methods have been applied. Results show that POMDP planning, which considers the evolution of the entire probability distribution over robot poses, produces significantly more robust behaviour when compared with a heuristic planner which considers only the most likely states and outcomes.
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Brooks, Alex M. "Parametric POMDPs for planning in continuous state spaces." Connect to full text, 2007. http://hdl.handle.net/2123/1861.
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Thesis (Ph. D.)--University of Sydney, 2007.Title from title screen (viewed 15 January 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Australian Centre for Field Robotics, School of Aerospace, Mechanical and Mechatronic Engineering. Includes bibliographical references. Also available in print form.
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Mayer, Rosirene. "A gramática da habitação mínima : análise do projeto arquitetônico da habitação de interesse social em Porto Alegre e Região Metropolitana." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/67057.
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A presente tese propõe um modelo geométrico paramétrico para a geração, baseada em regras, da geometria do projetos de Habitação de Interesse Social, HIS, adequada à realidade socioeconômica brasileira. A definição do modelo partiu da análise dos padrões existentes na morfologia dos projetos arquitetônicos de uma amostra da produção de HIS de Porto Alegre (Rio Grande do Sul, Brasil) e Região Metropolitana. A identificação destes padrões serviu para acessar os limites de variação e qualificação do projeto da HIS. Foram utilizadas representações adimensionais associadas a grafos de adjacência para descrição das relações espaciais mais freqüentes em dois níveis distintos porém relacionados - para o equipamento e para os compartimentos. O modelo de Gramáticas da Forma serviu à descrição das regras de composição e configuração do espaço e seus componentes. A análise comparativa do corpus e das necessidades programáticas forneceu a variação admissível dos parâmetros dimensionais. A implementação computacional do modelo geométrico resultante permitiu a exploração das variações paramétricas das alternativas de configuração de projeto. Os resultados permitiram verificar uma homogeneidade da estrutura sintática do corpus que ultrapassa os limites tipológicos. Parte das diferenças existentes entre os elementos da amostra podem ser atribuídas a variações paramétricas das partes e a sua influência mútua na composição da área total e da forma da unidade habitacional. Variações paramétricas de uma configuração podem servir para adaptar a inserção da unidade habitacional no lote ou no edifício. A aplicabilidade do modelo geométrico paramétrico pode ser vista sob dois aspectos interrelacionados: como matriz generativa para o desenvolvimento de projetos mais adequados a problemas específicos e, conseqüentemente, e como uma alternativa a padronização da produção habitacional.This thesis proposes a parametric geometrical model for the rule-based generation of the configurational geometry of social housing architectural designs, suitable to the Brazilian socioeconomic context. The model was based on analysis of existing patterns identified in the morphology of architectural designs from a sample of the social housing production in Porto Alegre and Metropolitan Area. The identification of these patterns was intended to access the limits of variation and qualification of social housing designs. The association between dimensionless representations and adjacency graphs was used for the description of spatial relations in two distinguished but related levels: for the furniture and the rooms. The shape grammars model was used to describe the geometrical rules governing the composition and configuration of the space and its components. The comparative analysis of the corpus and functional needs enabled to identify the admissible variation of the dimensional parameters. The computational implementation of the resulting geometrical model allowed the exploration of the parametric variations in the design configuration alternatives. The results showed homogeneity of syntactic structure of the corpus, which overcomes the typological limits.! Part of the differences between the elements of the sample may be attributed to the parametric variations in rooms and their mutual influence on the composition of the total area and the shape of the housing unit. The parametric variations in a design can also enable setting the location of the housing unit on a plot or in a building. The application of the parametric geometrical model can be seen in two interrelated aspects: as a generative matrix for the development of projects best suited to specific problems, and consequently, as an alternative to the standardization of housing production.
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Dubanchet, Vincent. "Modélisation et contrôle d’un robot spatial flexible pour la capture d’un débris en rotation." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0022/document.
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Les débris en orbite sont actuellement une source de préoccupation majeure pour les acteurs du spatial et pour le reste de la population, comme en témoignent les articles de presse et les œuvres cinématographiques sur le sujet. En effet, la présence de ces objets menace directement les astronautes en mission et les satellites en opération. Parmi les nombreuses options déjà envisagées pour les traiter, cette thèse se concentre sur l’approche robotique, en proposant des outils et des méthodes de modélisation et de contrôle pour un satellite chasseur équipé d’un bras manipulateur. Des modèles dynamiques et des schémas de simulation optimisés sont ainsi développés pour tout système multi-corps constitué d’une base mobile supportant un nombre quelconque d’appendices rigides ou flexibles. Par la suite, les trajectoires de capture sont générées en conservant la continuité en accélération avec le mouvement naturel du point cible, dans le but de saisir aussi délicatement que possible le débris en rotation. Le suivi de cette trajectoire par l’effecteur du robot chasseur est alors assuré par une loi de contrôle à deux niveaux, dont le réglage repose sur la synthèse H1 structurée. Une étude de robustesse est également mise en place pour assurer la stabilité et les performances du système en boucle fermée, malgré les changements de configuration du bras. Enfin, la validation des travaux de thèse est réalisée par voie numérique avec un simulateur haute-fidélité, et par voie pratique avec un banc d’essais robotique incluant des composants physiques en temps réelOn-orbit debris are currently causing deep concern for space agencies, related companies, and also among the population. ¿is is evidenced by the numerous scientific articles and recent movies on the matter. Indeed, these objects pose a serious threat for the astronauts on mission and for operational satellites. Among the various technical concepts already designed to address these threats, this thesis focuses on space robotics. Tools and methods are thus introduced for the modeling and control of a chaser satellite equipped with a manipulator. Dynamic models and optimized simulation schemes are developed to handle any multi-body system made up of amoving base embedding various appendages, either rigid or flexible. ¿en, a trajectory planner is designed to ensure acceleration continuity with the natural motion of the debris in order to perform a soft capture. ¿is reference trajectory is tracked by the end-effector of the chaser using a two-level control law, which is tuned by the structured H1 synthesis. A robustness analysis is also presented to assess the stability and the performances of the closed-loop system with respect to the motion of the robotic arm. Finally, the outcome of the thesis is validated by a twofold approach: by numerical means with a highfidelity simulator, and by practical ones with a robotic test bench including physical components in real time
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Stenger, Jérôme. "Optimal uncertainty quantification of a risk measurement from a computer code." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30082.
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La quantification des incertitudes lors d'une étude de sûreté peut être réalisée en modélisant les paramètres d'entrée du système physique par des variables aléatoires. Afin de propager les incertitudes affectant les entrées, un modèle de simulation numérique reproduisant la physique du système est exécuté avec différentes combinaisons des paramètres d'entrée, générées suivant leur loi de probabilité jointe. Il est alors possible d'étudier la variabilité de la sortie du code, ou d'estimer certaines quantités d'intérêt spécifiques. Le code étant considéré comme une boîte noire déterministe, la quantité d'intérêt dépend uniquement du choix de la loi de probabilité des entrées. Toutefois, cette distribution de probabilité est elle-même incertaine. En général, elle est choisie grâce aux avis d'experts, qui sont subjectifs et parfois contradictoires, mais aussi grâce à des données expérimentales souvent en nombre insuffisant et entachées d'erreurs. Cette variabilité dans le choix de la distribution se propage jusqu'à la quantité d'intérêt. Cette thèse traite de la prise en compte de cette incertitude dite de deuxième niveau. L'approche proposée, connue sous le nom d'Optimal Uncertainty Quantification (OUQ) consiste à évaluer des bornes sur la quantité d'intérêt. De ce fait on ne considère plus une distribution fixée, mais un ensemble de mesures de probabilité sous contraintes de moments sur lequel la quantité d'intérêt est optimisée. Après avoir exposé des résultats théoriques visant à réduire l'optimisation de la quantité d'intérêt aux point extrémaux de l'espace de mesures de probabilité, nous présentons différentes quantités d'intérêt vérifiant les hypothèses du problème. Cette thèse illustre l'ensemble de la méthodologie sur plusieurs cas d'applications, l'un d'eux étant un cas réel étudiant l'évolution de la température de gaine du combustible nucléaire en cas de perte du réfrigérantUncertainty quantification in a safety analysis study can be conducted by considering the uncertain inputs of a physical system as a vector of random variables. The most widespread approach consists in running a computer model reproducing the physical phenomenon with different combinations of inputs in accordance with their probability distribution. Then, one can study the related uncertainty on the output or estimate a specific quantity of interest (QoI). Because the computer model is assumed to be a deterministic black-box function, the QoI only depends on the choice of the input probability measure. It is formally represented as a scalar function defined on a measure space. We propose to gain robustness on the quantification of this QoI. Indeed, the probability distributions characterizing the uncertain input may themselves be uncertain. For instance, contradictory expert opinion may make it difficult to select a single probability distribution, and the lack of information in the input variables affects inevitably the choice of the distribution. As the uncertainty on the input distributions propagates to the QoI, an important consequence is that different choices of input distributions will lead to different values of the QoI. The purpose of this thesis is to account for this second level uncertainty. We propose to evaluate the maximum of the QoI over a space of probability measures, in an approach known as optimal uncertainty quantification (OUQ). Therefore, we do not specify a single precise input distribution, but rather a set of admissible probability measures defined through moment constraints. The QoI is then optimized over this measure space. After exposing theoretical results showing that the optimization domain of the QoI can be reduced to the extreme points of the measure space, we present several interesting quantities of interest satisfying the assumption of the problem. This thesis illustrates the methodology in several application cases, one of them being a real nuclear engineering case that study the evolution of the peak cladding temperature of fuel rods in case of an intermediate break loss of coolant accident
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Ajaz, Mahnoor. "Finite Difference Time Domain Modelling of Ultrasonic Parametric Arrays in Two-Dimensional Spaces." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619109761801613.
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Серьожко, А. С. "Моделювання динаміки двопотокової нестійкості у двошвидкісному гвинтовому електронному пучку, який рухається у повздовжньому електричному полі." Master's thesis, Сумський державний університет, 2019. http://essuir.sumdu.edu.ua/handle/123456789/73840.
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Grimm, Alexander Rudolf. "Parametric Dynamical Systems: Transient Analysis and Data Driven Modeling." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83840.
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Dynamical systems are a commonly used and studied tool for simulation, optimization and design. In many applications such as inverse problem, optimal control, shape optimization and uncertainty quantification, those systems typically depend on a parameter. The need for high fidelity in the modeling stage leads to large-scale parametric dynamical systems. Since these models need to be simulated for a variety of parameter values, the computational burden they incur becomes increasingly difficult. To address these issues, parametric reduced models have encountered increased popularity in recent years.
We are interested in constructing parametric reduced models that represent the full-order system accurately over a range of parameters. First, we define a global joint error mea- sure in the frequency and parameter domain to assess the accuracy of the reduced model. Then, by assuming a rational form for the reduced model with poles both in the frequency and parameter domain, we derive necessary conditions for an optimal parametric reduced model in this joint error measure. Similar to the nonparametric case, Hermite interpolation conditions at the reflected images of the poles characterize the optimal parametric approxi- mant. This result extends the well-known interpolatory H2 optimality conditions by Meier and Luenberger to the parametric case. We also develop a numerical algorithm to construct locally optimal reduced models. The theory and algorithm are data-driven, in the sense that only function evaluations of the parametric transfer function are required, not access to the internal dynamics of the full model.
While this first framework operates on the continuous function level, assuming repeated transfer function evaluations are available, in some cases merely frequency samples might be given without an option to re-evaluate the transfer function at desired points; in other words, the function samples in parameter and frequency are fixed. In this case, we construct a parametric reduced model that minimizes a discretized least-squares error in the finite set of measurements. Towards this goal, we extend Vector Fitting (VF) to the parametric case, solving a global least-squares problem in both frequency and parameter. The output of this approach might lead to a moderate size reduced model. In this case, we perform a post- processing step to reduce the output of the parametric VF approach using H2 optimal model
reduction for a special parametrization. The final model inherits the parametric dependence of the intermediate model, but is of smaller order.
A special case of a parameter in a dynamical system is a delay in the model equation, e.g., arising from a feedback loop, reaction time, delayed response and various other physical phenomena. Modeling such a delay comes with several challenges for the mathematical formulation, analysis, and solution. We address the issue of transient behavior for scalar delay equations. Besides the choice of an appropriate measure, we analyze the impact of the coefficients of the delay equation on the finite time growth, which can be arbitrary large purely by the influence of the delay.Ph. D.
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Varagnolo, Damiano. "Distributed Parametric-Nonparametric Estimation in Networked Control Systems." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3421610.
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In the framework of parametric and nonparametric distributed estimation, we introduce and mathematically analyze some consensus-based regression strategies characterized by a guess of the number of agents in the network as a parameter. The parametric estimators assume a-priori information about the finite set of parameters to be estimated, while the the nonparametric use a reproducing kernel Hilbert space as the hypothesis space. The analysis of the proposed distributed regressors offers some sufficient conditions assuring the estimators to perform better, under the variance of the estimation error metric, than local optimal ones. Moreover it characterizes, under euclidean distance metrics, the performance losses of the distributed estimators with respect to centralized optimal ones. We also offer a novel on-line algorithm that distributedly computes certificates of quality attesting the goodness of the estimation results, and show that the nonparametric distributed regressor is an approximate distributed Regularization Network requiring small computational, communication and data storage efforts. We then analyze the problem of estimating a function from different noisy data sets collected by spatially distributed sensors and subject to unknown temporal shifts, and perform time delay estimation through the minimization of functions of inner products in reproducing kernel Hilbert spaces.
Due to the importance of the knowledge of the number of agents in the previously analyzed algorithms, we also propose a design methodology for its distributed estimation. This algorithm is based on the following paradigm: some locally randomly generated values are exchanged among the various sensors, and are then modified by known consensus-based strategies. Statistical analysis of the a-consensus values allows the estimation of the number of sensors participating in the process. The first main feature of this approach is that algorithms are completely distributed, since they do not require leader election steps. Moreover sensors are not requested to transmit authenticating information like identification numbers or similar data, and thus the strategy can be implemented even if privacy problems arise. After a rigorous formulation of the paradigm we analyze some practical examples, fully characterize them from a statistical point of view, and finally provide some general theoretical results among with asymptotic analyses.In questa tesi vengono introdotti e analizzati alcuni algoritmi di regressione distribuita parametrica e nonparametrica, basati su tecniche di consenso e parametrizzati da un parametro il cui significato è una stima del numero di sensori presenti nella rete. Gli algoritmi parametrici assumono la conoscenza di informazione a-priori sulle quantità da stimare, mentre quelli nonparametrici utilizzano come spazio delle ipotesi uno spazio di Hilbert a nucleo riproducente. Dall'analisi degli stimatori distribuiti proposti si ricavano alcune condizioni sufficienti che, se assicurate, garantiscono che le prestazioni degli stimatori distribuiti sono migliori di quelli locali (usando come metrica la varianza dell'errore di stima). Inoltre dalla stessa analisi si caratterizzano le perdite di prestazioni che si hanno usando gli stimatori distribuiti invece che quelli centralizzati e ottimi (usando come metrica la distanza euclidea tra le due diverse stime ottenute). Inoltre viene offerto un nuovo algoritmo che calcola in maniera distribuita dei certificati di qualità che garantiscono la bontà dei risultati ottenuti con gli stimatori distribuiti. Si mostra inoltre come lo stimatore nonparametrico distribuito proposto sia in realtà una versione approssimata delle cosiddette ``Reti di Regolarizzazione'', e come esso richieda poche risorse computazionali, di memoria e di comunicazione tra sensori. Si analizza quindi il caso di sensori spazialmente distribuiti e soggetti a ritardi temporali sconosciuti. Si mostra dunque come si possano stimare, minimizzando opportune funzioni di prodotti interni negli spazi di Hilbert precedentemente considerati, sia la funzione vista dai sensori che i relativi ritardi visti da questi. A causa dell'importanza della conoscenza del numero di agenti negli algoritmi proposti precedentemente, viene proposta una nuova metodologia per sviluppare algoritmi di stima distribuita di tale numero, basata sulla seguente idea: come primo passo gli agenti generano localmente alcuni numeri, in maniera casuale e da una densità di probabilità nota a tutti. Quindi i sensori si scambiano e modificano questi dati usando algoritmi di consenso quali la media o il massimo; infine, tramite analisi statistiche sulla distribuzione finale dei dati modificati, si può ottenere dell'informazione su quanti agenti hanno partecipato al processo di consenso e modifica. Una caratteristica di questo approccio è che gli algoritmi sono completamente distribuiti, in quanto non richiedono passi di elezione di leaders. Un'altra è che ai sensori non è richiesto di trasmettere informazioni sensibili quali codici identificativi o altro, quindi la strategia è implementabile anche se in presenza di problemi di riservatezza. Dopo una formulazione rigorosa del paradigma, analizziamo alcuni esempi pratici, li caratterizziamo completamente dal punto di vista statistico, e infine offriamo alcuni risultati teorici generali e analisi asintotiche.
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Pavel, Dimovski. "Translation invariant Banach spaces of distributions and boundary values of integral transform." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2015. https://www.cris.uns.ac.rs/record.jsf?recordId=93767&source=NDLTD&language=en.
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We use common notation ∗ for distribution (Scshwartz), (Mp) (Beurling) i {Mp} (Roumieu) setting. We introduce and study new (ultra) distribution spaces, the test function spaces D∗E and their strong duals D'∗E’*.These spaces generalize the spaces D∗Lq , D'∗Lp , B’* and their weighted versions. The construction of our new (ultra)distribution spaces is based on the analysis of a suitable translation-invariant Banach space of (ultra)distribution E with continuous translation group, which turns out to be a convolution module over the Beurling algebra L1ω, where the weight ω is related to the translation operators on E. The Banach space E’∗ stands for L1ωˇ ∗ E’. We apply our results to the study of the convolution of ultradistributions. The spaces of convolutors O’∗C (Rn) for tempered ultradistributions are analyzed via the duality with respect to the test functionspaces O∗C (Rn), introduced in this thesis. Using the properties of translationinvariantBanach space of ultradistributions E we obtain a full characterization ofthe general convolution of Roumieu ultradistributions via the space of integrableultradistributions is obtained. We show: The convolution of two Roumieu ultradistributions T, S ∈ D’{Mp} (Rn) exists if and only if (φ ∗ Š) T ∈ D’{Mp}L1(Rn) for every φ ∈ D {Mp} (Rn). We study boundary values of holomorphic functions defined in tube domains. New edge of the wedge theorems are obtained. The resultsare then applied to represent D’E’* as a quotient space of holomorphic functions.We also give representations of elements of D’E’* via the heat kernel method.Koristimo oznaku ∗ za distribuciono (Svarcovo), (Mp) (Berlingovo) i {Mp} (Roumieuovo) okruženje. Uvodimo i prouavamo nove (ultra)distribucione prostore, test funkcijske prostore D∗E i njihove duale D'∗E'*. Ovi prostori uopštavaju prostore D∗Lq , D'∗Lp , B'∗ i njihove težinske verzije. Konstrukcija naših novih (ultra)distribucionih prostora je zasnovana na analizi odgovarajuićh translaciono - invarijantnih Banahovih prostora (ultra)distribucija koje označavamo sa E. Ovi prostori imaju neprekidnu grupu translacija, koja je konvolucioni modul nad Beurlingovom algebrom L1ω, gde je težina ω povezana sa operatorima translacije prostora E. Banahov prostor E'∗ označava prostor L1ω˅ ∗ E'. Koristeći dobijene rezultata proučavamo konvoluciju ultradistribucija. Prostori konvolutora O'∗C (Rn) temperiranih ultradistribucija, analizirani su pomoću dualnosti test funkcijskih prostora O∗C (Rn), definisanih u ovoj tezi. Koristeći svojstva translaciono - invarijantnih Banahovih prostora temperiranih ultradistribucija, opet označenih sa E, dobijamo karakterizaciju konvolucije Romuieu-ovih ultradistribucija, preko integrabilnih ultradistribucija. Dokazujemo da: konvolucija dve Roumieu-ove ultradistribucija T, S ∈ D'{Mp} (Rn) postoji ako i samo ako (φ ∗ Sˇ)T ∈ D'{Mp} L1 (Rn) za svaki φ ∈ D{Mp}(Rn). Takođe, proučavamo granične vrednosti holomorfnih funkcija definisanih na tubama. Dokazane su nove teoreme ”otrog klina”. Rezultati se zatim koriste za prezentaciju D'E'∗ preko faktor prostora holomorfnih funkcija. Takođe, data je prezentacija elemente D'E'∗ koristeći heat kernel metode.
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Jenča, Pavol. "Identifikace parametrů elektrických motorů metodou podprostorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219678.
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The electrical motors parameters identification is solved in this master’s thesis using subspace based methods. Electrical motors are simulated in Matlab/Simulink interactive environment, specifically permanent magnet DC motor and permanent magnet synchronous motor. Identification is developed in Matlab interactive environment. Different types of subspace algorithms are used for the estimation of parameters. Results of subspace parameters estimation are compared with least squares parameters estimation. The thesis describes subspace method, types of subspace algorithms, used electrical motors, nonlinear approach of identification and comparation of parameters identification.
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Duchemin, Quentin. "Growth dynamics of large networks using hidden Markov chains." Thesis, Université Gustave Eiffel, 2022. https://tel.archives-ouvertes.fr/tel-03749513.
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La première partie de cette thèse vise à introduire de nouveaux modèles de graphes aléatoires rendant compte de l'évolution temporelle des réseaux. Plus précisément, nous nous concentrons sur des modèles de croissance où à chaque instant un nouveau noeud s'ajoute au graphe existant. Nous attribuons à ce nouvel entrant des propriétés qui caractérisent son pouvoir de connectivité au reste du réseau et celles-ci dépendent uniquement du noeud précédemment introduit. Nos modèles de graphes aléatoires sont donc régis par une dynamique markovienne latente caractérisant la séquence de noeuds du graphe. Nous nous intéresserons particulièrement au Stochastic Block Model et aux Graphes Aléatoires Géométriques pour lesquels nous proposons des algorithmes permettant d'estimer les paramètres du modèle. Nous montrons ensuite comment ce travail d'estimation nous permet de résoudre des problèmes de prédiction de lien ou de filtrage collaboratif dans les graphes.L'étude théorique des algorithmes précédemment décrits mobilisent des résultats probabilistes poussés. Nous avons notamment dû recourir à une inégalité de concentration pour les U-statistiques dans un cadre dépendant. Peu nombreux sont les travaux ayant abordé cette épineuse question et l'existant considère des jeux d'hypothèses ne répondant pas à nos besoins. Aussi, la deuxième partie de ce manuscrit sera consacrée à la preuve d'une inégalité de concentration pour les U-statistiques d'ordre deux pour des chaînes de Markov uniformément ergodique. Dans le Chapitre 5, nous exploitons notre résultat de concentration pour les U-statistiques pour apporter de nouvelles contributions à trois domaines très actifs des Statistiques et du Machine Learning.Toujours motivés par des problèmes de prédictions liens dans les graphes, nous nous intéressons dans un dernier chapitre aux procédures d'inférence post-sélection dans le cadre de la régression logistique avec pénalité $L^1$. Nous prouvons un théorème central limite sous la distribution conditionnelle à l'événement de sélection et nous en déduisons des procédures de test et des intervalles de confiance asymptotiquement validesThe first part of this thesis aims at introducing new models of random graphs that account for the temporal evolution of networks. More precisely, we focus on growth models where at each instant a new node is added to the existing graph. We attribute to this new entrant properties that characterize its connectivity to the rest of the network and these properties depend only on the previously introduced node. Our random graph models are thus governed by a latent Markovian dynamic characterizing the sequence of nodes in the graph. We are particularly interested in the Stochastic Block Model and in Random Geometric Graphs for which we propose algorithms to estimate the unknown parameters or functions defining the model. We then show how these estimates allow us to solve link prediction or collaborative filtering problems in networks.The theoretical analysis of the above-mentioned algorithms requires advanced probabilistic tools. In particular, one of our proof is relying on a concentration inequality for U-statistics in a dependent framework. Few papers have addressed this thorny question and existing works consider sets of assumptions that do not meet our needs. Therefore, the second part of this manuscript will be devoted to the proof of a concentration inequality for U-statistics of order two for uniformly ergodic Markov chains. In Chapter 5, we exploit this concentration result for U-statistics to make new contributions to three very active areas of Statistics and Machine Learning.Still motivated by link prediction problems in graphs, we study post-selection inference procedures in the framework of logistic regression with $L^1$ penalty. We prove a central limit theorem under the distribution conditional on the selection event and derive asymptotically valid testing procedures and confidence intervals
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Mure, Simon. "Classification non supervisée de données spatio-temporelles multidimensionnelles : Applications à l’imagerie." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI130/document.
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Avec l'augmentation considérable d'acquisitions de données temporelles dans les dernières décennies comme les systèmes GPS, les séquences vidéo ou les suivis médicaux de pathologies ; le besoin en algorithmes de traitement et d'analyse efficaces d'acquisition longitudinales n'a fait qu'augmenter. Dans cette thèse, nous proposons une extension du formalisme mean-shift, classiquement utilisé en traitement d'images, pour le groupement de séries temporelles multidimensionnelles. Nous proposons aussi un algorithme de groupement hiérarchique des séries temporelles basé sur la mesure de dynamic time warping afin de prendre en compte les déphasages temporels. Ces choix ont été motivés par la nécessité d'analyser des images acquises en imagerie par résonance magnétique sur des patients atteints de sclérose en plaques. Cette maladie est encore très méconnue tant dans sa genèse que sur les causes des handicaps qu'elle peut induire. De plus aucun traitement efficace n'est connu à l'heure actuelle. Le besoin de valider des hypothèses sur les lésions de sclérose en plaque nous a conduit à proposer des méthodes de groupement de séries temporelles ne nécessitant pas d'a priori sur le résultat final, méthodes encore peu développées en traitement d'imagesDue to the dramatic increase of longitudinal acquisitions in the past decades such as video sequences, global positioning system (GPS) tracking or medical follow-up, many applications for time-series data mining have been developed. Thus, unsupervised time-series data mining has become highly relevant with the aim to automatically detect and identify similar temporal patterns between time-series. In this work, we propose a new spatio-temporal filtering scheme based on the mean-shift procedure, a state of the art approach in the field of image processing, which clusters multivariate spatio-temporal data. We also propose a hierarchical time-series clustering algorithm based on the dynamic time warping measure that identifies similar but asynchronous temporal patterns. Our choices have been motivated by the need to analyse magnetic resonance images acquired on people affected by multiple sclerosis. The genetics and environmental factors triggering and governing the disease evolution, as well as the occurrence and evolution of individual lesions, are still mostly unknown and under intense investigation. Therefore, there is a strong need to develop new methods allowing automatic extraction and quantification of lesion characteristics. This has motivated our work on time-series clustering methods, which are not widely used in image processing yet and allow to process image sequences without prior knowledge on the final results
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Dittrich, Petr. "Odhad Letových Parametrů Malého Letounu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2017. http://www.nusl.cz/ntk/nusl-412582.
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Tato práce je zaměřena na odhad letových parametrů malého letounu, konkrétně letounu Evektor SportStar RTC. Pro odhad letových parametrů jsou použity metody "Equation Error Method", "Output Error Method" a metody rekurzivních nejmenších čtverců. Práce je zaměřena na zkoumání charakteristik aerodynamických parametrů podélného pohybu a ověření, zda takto odhadnuté letové parametry odpovídají naměřeným datům a tudíž vytvářejí předpoklad pro realizaci dostatečně přesného modelu letadla. Odhadnuté letové parametry jsou dále porovnávány s a-priorními hodnotami získanými s využitím programů Tornado, AVL a softwarovéverze sbírky Datcom. Rozdíly mezi a-priorními hodnotami a odhadnutými letovými paramatery jsou porovnány s korekcemi publikovanými pro subsonické letové podmínky modelu letounu F-18 Hornet.
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BAIMA, LUCIA. "Intencity. Il parametro intensità misura lo spazio-tempo dell'architettura urbana. | Intencity. Measuring the space-time of urban architecture: the intensity parameter." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2694235.
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This work intends to address new questions posed by contemporary urban context, concerning
the reactivation of use and practices within the consolidated spaces of the city: it becomes
necessary to implement qualitative and social-dynamic instruments such as Intensity. The base
to define and build this parameter is set through its ethymological analysis, thorugh the different
interpretations about the city and the role of project in generating vitality within the urban
space. This matrix of analysis is applied to New York City as a case study - chosen for its spatial
conformation, its history and its social practices - selecting projects ranging across different
scales, from the house to the city, thus becoming the testing ground of intensity, to investigate
urban transformation and different uses of the space: a design/analysis process aiming to make
intensity an operational parameter in architecture.
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Van, der Walt Christiaan Maarten. "Maximum-likelihood kernel density estimation in high-dimensional feature spaces /| C.M. van der Walt." Thesis, North-West University, 2014. http://hdl.handle.net/10394/10635.
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With the advent of the internet and advances in computing power, the collection of very large high-dimensional datasets has become feasible { understanding and modelling high-dimensional data has thus become a crucial activity, especially in the field of pattern recognition. Since non-parametric density estimators are data-driven and do not require or impose a pre-defined probability density function on data, they are very powerful tools for probabilistic data modelling and analysis. Conventional non-parametric density estimation methods, however, originated from the field of statistics and were not originally intended to perform density estimation in high-dimensional features spaces { as is often encountered in real-world pattern recognition tasks. Therefore we address the fundamental problem of non-parametric density estimation in high-dimensional feature spaces in this study. Recent advances in maximum-likelihood (ML) kernel density estimation have shown that kernel density estimators hold much promise for estimating nonparametric probability density functions in high-dimensional feature spaces. We therefore derive two new iterative kernel bandwidth estimators from the maximum-likelihood (ML) leave one-out objective function and also introduce a new non-iterative kernel bandwidth estimator (based on the theoretical bounds of the ML bandwidths) for the purpose of bandwidth initialisation. We name the iterative kernel bandwidth estimators the minimum leave-one-out entropy (MLE) and global MLE estimators, and name the non-iterative kernel bandwidth estimator the MLE rule-of-thumb estimator. We compare the performance of the MLE rule-of-thumb estimator and conventional kernel density estimators on artificial data with data properties that are varied in a controlled fashion and on a number of representative real-world pattern recognition tasks, to gain a better understanding of the behaviour of these estimators in high-dimensional spaces and to determine whether these estimators are suitable for initialising the bandwidths of iterative ML bandwidth estimators in high dimensions. We find that there are several regularities in the relative performance of conventional kernel density estimators across different tasks and dimensionalities and that the Silverman rule-of-thumb bandwidth estimator performs reliably across most tasks and dimensionalities of the pattern recognition datasets considered, even in high-dimensional feature spaces. Based on this empirical evidence and the intuitive theoretical motivation that the Silverman estimator optimises the asymptotic mean integrated squared error (assuming a Gaussian reference distribution), we select this estimator to initialise the bandwidths of the iterative ML kernel bandwidth estimators compared in our simulation studies. We then perform a comparative simulation study of the newly introduced iterative MLE estimators and other state-of-the-art iterative ML estimators on a number of artificial and real-world high-dimensional pattern recognition tasks. We illustrate with artificial data (guided by theoretical motivations) under what conditions certain estimators should be preferred and we empirically confirm on real-world data that no estimator performs optimally on all tasks and that the optimal estimator depends on the properties of the underlying density function being estimated. We also observe an interesting case of the bias-variance trade-off where ML estimators with fewer parameters than the MLE estimator perform exceptionally well on a wide variety of tasks; however, for the cases where these estimators do not perform well, the MLE estimator generally performs well. The newly introduced MLE kernel bandwidth estimators prove to be a useful contribution to the field of pattern recognition, since they perform optimally on a number of real-world pattern recognition tasks investigated and provide researchers and
practitioners with two alternative estimators to employ for the task of kernel density
estimation.PhD (Information Technology), North-West University, Vaal Triangle Campus, 2014
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Manera, Leandro Tiago 1977. "Determinação de regras de projeto e de parametros de simulação de um processo nMOS para fabricação de circuitos integrados." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259706.
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Orientador: Peter Jurgen TatschDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-03T21:34:36Z (GMT). No. of bitstreams: 1 Manera_LeandroTiago_M.pdf: 1877187 bytes, checksum: a0545f28b99f4d215578ff2ba56d909f (MD5) Previous issue date: 2002
Mestrado
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De, Chiusole Debora. "Sviluppo e Applicazioni di Modelli Formali per la Valutazione Adattiva della Conoscenza e dell'Apprendimento nell'Ambito della Knowledge Space Theory." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424002.
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The five studies presented in this thesis have been carried out in the area of knowledge space theory (KST), a recent mathematical theory providing an important framework for the formal development of computerized web-based systems aimed at assessing individual knowledge and learning. The basic concept at the core of the entire theory is that of knowledge state, that is the set of problems that a student is able to solve, in a certain filed of knowledge. The collection of all knowledge states that occurs in a population of students is called the knowledge structure. A knowledge structure is a deterministic model of the organization of knowledge in a particular domain. Its empirical validation is possible by a probabilistic assessment of its plausibility. The basic local independence model (BLIM) is a probabilistic model developed to this aim. Despite it is the most widely used model in KST, issues relating its applicability were open. The overall objective of the first three studies presented in this thesis was to solve some of these problems, in order to improve the validity of empirical applications of the model. In the KST framework, the notion of knowledge state does not provide cognitive interpretations. Instead, in the competence-based KST (CbKST) the main objective of the assessment becomes that of identifying the competence state of a student, which is the set of skills she masters. The other two studies that are introduced were developed within this extended theoretical framework. The general aim was to fill some gaps regarding both the probabilistic and the deterministic levels of CbKST's models.Le cinque ricerche che si presentano in questa tesi si sviluppano entro la knowledge space theory, una teoria matematica recente che fornisce un importante quadro di riferimento formale per lo sviluppo di sistemi computerizzati web-based che abbiano l'obiettivo di valutare la conoscenza e l'apprendimento degli individui. La nozione al centro dell'intera teoria è quella di di conoscenza, cioè l'insieme dei problemi che uno studente è capace di risolvere, in un certo dominio di conoscenza. La collezione di tutti gli stati di conoscenza osservabili in una popolazione di studenti costituisce una struttura di conoscenza. Le strutture di conoscenza sono un modello deterministico teorico dell'organizzazione della conoscenza all'interno di un particolare dominio. La loro validazione empirica è resa possibile grazie alla verifica probabilistica della loro plausibilità. Il basic local independence model (BLIM) è un modello probabilistico che è stato sviluppato a questo scopo. Nonostante sia il modello più utilizzato nella KST, problemi relativi alla sua applicabilità rimanevano ancora aperti. L'obiettivo generale delle prime tre ricerche che si presentano in questa tesi, è stato quello di risolvere questi problemi per conferire una maggiore validità alle applicazioni empiriche del modello. Nella KST, la nozione di stato di conoscenza non fornisce alcun tipo di interpretazione cognitiva. Invece, nella competence-based KST (CbKST) l'obiettivo principale della valutazione diviene quello individuare lo stato di competenza dello studente, ovvero l'insieme delle abilità che possiede. Le altre due ricerche che si presentano nella tesi si collocano all'interno di questo quadro teorico. Esse hanno avuto l'obiettivo di colmare alcune mancanze relative della CbKST, una di tipo probabilistico e l'altra di tipo deterministico.
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Diouf, Cherif El Valid. "Modélisation comportementale de drivers de ligne de transmission pour des besoins d'intégrité du signal et de compatibilité électromagnétique." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0040/document.
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La miniaturisation de circuits intégrés, les hautes fréquences de fonctionnement, la baisse des potentiels d'alimentation, les fortes densités d'intégration rendent les signaux numériques propagés sur les interconnexions très susceptibles à la dégradation voire à la corruption. En vue d’évaluer la compatibilité électromagnétique et l’intégrité du signal il est nécessaire de disposer dès les premières phases de développement de modèles précis de ces interconnexions pour les insérer dans les simulateurs temporels. Nos travaux s'inscrivent dans ce contexte et concernent plus particulièrement la modélisation comportementale des buffers et drivers de ligne de transmission. Ils ont abouti à une approche originale de modélisation notamment basée sur les séries de Volterra-Laguerre. Les modèles boites noires développés disposent d’une implémentation SPICE assez simple autorisant ainsi une très bonne portabilité. Ils sont faciles à identifier et disposent d’une complexité paramétrique permettant un gain important de temps de simulation vis-à-vis des modèles transistors des drivers. En outre les méthodes développées permettent une modélisation dynamique non linéaire plus précise du port de sortie, et une gestion plus générale des entrées autorisant notamment une très bonne prise en compte du régime de sur-cadencement ce que par exemple ne fait pas le standard IBISIntegrated circuits miniaturization, high operating frequencies, lower supply voltages, high-density integration make digital signals propagating on interconnects highly vulnerable to degradation. Assessing EMC and signal integrity in the early stages of the design flow requires accurate interconnect models allowing for efficient time-domain simulations. In this context, our work addressed the issue of behavioral modeling of transmission line buffers, and particularly that of drivers. The main result is an original modeling approach partially based on Volterra-Laguerre series. The black box models we developed have a fairly simple implementation in SPICE thus allowing a very good portability. They are easy to identify and have a parametric complexity allowing a large gain in simulation time with respect to transistor driver models. In addition, the developed methods allow a more accurate output port nonlinear dynamics modeling, and a more general management of inputs. A very good reproduction of driver behaviour in overclocking conditions provides a significant advantage over standard IBIS models
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Mai, Van Khanh. "Méthodes avancées de traitement de la parole et de réduction de bruit pour les terminaux mobiles." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0008/document.
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Cette thèse traite d'un des problèmes les plus stimulants dans le traitement de la parole concernant la prothèse auditive, où seulement un capteur est disponible avec de faibles coûts de calcul, de faible utilisation d'énergie et l'absence de bases de données. Basée sur les récents résultats dans les deux estimations statistiques paramétriques et non-paramétriques, ainsi que la représentation parcimonieuse. Cette étude propose quelques techniques non seulement pour améliorer la qualité et l'intelligibilité de la parole, mais aussi pour s'attaquer au débruitage du signal audio en général.La thèse est divisée en deux parties ; Dans la première partie, on aborde le problème d'estimation de la densité spectrale de puissance du bruit, particulièrement pour le bruit non-stationnaire. Ce problème est une des parties principales du traitement de la parole du mono-capteur. La méthode proposée prend en compte le modèle parcimonieux de la parole dans le domaine transféré. Lorsque la densité spectrale de puissance du bruit est estimée, une approche sémantique est exploitée pour tenir compte de la présence ou de l'absence de la parole dans la deuxième partie. En combinant l'estimation Bayésienne et la détection Neyman-Pearson, quelques estimateurs paramétriques sont développés et testés dans le domaine Fourier. Pour approfondir la performance et la robustesse de débruitage du signal audio, une approche semi-paramétrique est considérée. La conjointe détection et estimation peut être interprétée par Smoothed Sigmoid-Based Shrinkage (SSBS). Ainsi, la méthode Bloc-SSBS est proposée afin de prendre en compte les atomes voisinages dans le domaine temporel-fréquentiel. De plus, pour améliorer fructueusement la qualité de la parole et du signal audio, un estimateur Bayésien est aussi dérivé et combiné avec la méthode Bloc-SSBS. L'efficacité et la pertinence de la stratégie dans le domaine transformée cosinus pour les débruitages de la parole et de l'audio sont confirmées par les résultats expérimentauxThis PhD thesis deals with one of the most challenging problem in speech enhancement for assisted listening where only one micro is available with the low computational cost, the low power usage and the lack out of the database. Based on the novel and recent results both in non-parametric and parametric statistical estimation and sparse representation, this thesis work proposes several techniques for not only improving speech quality and intelligibility and but also tackling the denoising problem of the other audio signal. In the first major part, our work addresses the problem of the noise power spectrum estimation, especially for non-stationary noise, that is the key part in the single channel speech enhancement. The proposed approach takes into account the weak-sparseness model of speech in the transformed model. Once the noise power spectrum has been estimated, a semantic road is exploited to take into consideration the presence or absence of speech in the second major part. By applying the joint of the Bayesian estimator and the Neyman-Pearson detection, some parametric estimators were developed and tested in the discrete Fourier transform domain. For further improve performance and robustness in audio denoising, a semi-parametric approach is considered. The joint detection and estimation can be interpreted by Smoothed Sigmoid-Based Shrinkage (SSBS). Thus, Block-SSBS is proposed to take into additionally account the neighborhood bins in the time-frequency domain. Moreover, in order to enhance fruitfully speech and audio, a Bayesian estimator is also derived and combined with Block-SSBS. The effectiveness and relevance of this strategy in the discrete Cosine transform for both speech and audio denoising are confirmed by experimental results
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Papež, Milan. "Monte Carlo identifikační strategie pro stavové modely." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400416.
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Stavové modely jsou neobyčejně užitečné v mnoha inženýrských a vědeckých oblastech. Jejich atraktivita vychází především z toho faktu, že poskytují obecný nástroj pro popis široké škály dynamických systémů reálného světa. Nicméně, z důvodu jejich obecnosti, přidružené úlohy inference parametrů a stavů jsou ve většině praktických situacích nepoddajné. Tato dizertační práce uvažuje dvě zvláště důležité třídy nelineárních a ne-Gaussovských stavových modelů: podmíněně konjugované stavové modely a Markovsky přepínající nelineární modely. Hlavní rys těchto modelů spočívá v tom, že---navzdory jejich nepoddajnosti---obsahují poddajnou podstrukturu. Nepoddajná část požaduje abychom využily aproximační techniky. Monte Carlo výpočetní metody představují teoreticky a prakticky dobře etablovaný nástroj pro řešení tohoto problému. Výhoda těchto modelů spočívá v tom, že poddajná část může být využita pro zvýšení efektivity Monte Carlo metod tím, že se uchýlíme k Rao-Blackwellizaci. Konkrétně, tato doktorská práce navrhuje dva Rao-Blackwellizované částicové filtry pro identifikaci buďto statických anebo časově proměnných parametrů v podmíněně konjugovaných stavových modelech. Kromě toho, tato práce adoptuje nedávnou particle Markov chain Monte Carlo metodologii pro návrh Rao-Blackwellizovaných částicových Gibbsových jader pro vyhlazování stavů v Markovsky přepínajících nelineárních modelech. Tyto jádra jsou posléze použity pro inferenci parametrů metodou maximální věrohodnosti v uvažovaných modelech. Výsledné experimenty demonstrují, že navržené algoritmy překonávají příbuzné techniky ve smyslu přesnosti odhadu a výpočetního času.
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Děcká, Klára. "Interferometrické měření fázových změn optického svazku v turbulenci." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377040.
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This master’s thesis deals with the impact of atmospheric turbulence on phase changes of a free space optical signal. This problematic is investigated by the interferometric method. A part of the thesis is focused on the phenomenon of atmospheric turbulence. Then the physical effect of interference is discussed and optical interferometers are described. The experimental part of the thesis is focused on measurement of phase shift of optical signal by interferometric method. The result of the thesis is to determine how phase shift of an optical beam depends on the strength of turbulence.
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Húserka, Jozef. "Návrh reverberátoru pro simulaci akustiky prostoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220649.
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This thesis deals with artificial simulation of acoustic spaces by using reverberators. Output of this document consists of four reverberation algorithms and function that evaluates objective parameters of acoustic space from impulse responses. Reverberators and script were implemented using Matlab. Graphical user interface is used to present all of the algorithms for easier usability. First chapter deals with objective parameters of acoustic spaces and the ways they are computed from impulse response. Second chapter describes various structures which are used to build reverberators. Those structures are used in third chapter in implementations of reverberators. Third chapter also compares all implemented reverberators . In last chapter experiment was made. Impulse responses of three spaces were measured and subsequently aproximated by algorithms implemented in this thesis.
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Kamari, Halaleh. "Qualité prédictive des méta-modèles construits sur des espaces de Hilbert à noyau auto-reproduisant et analyse de sensibilité des modèles complexes." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE010.
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Ce travail porte sur le problème de l'estimation d'un méta-modèle d'un modèle complexe, noté m. Le modèle m dépend de d variables d'entrées X1,...,Xd qui sont indépendantes et ont une loi connue. Le méta-modèle, noté f∗, approche la décomposition de Hoeffding de m et permet d'estimer ses indices de Sobol. Il appartient à un espace de Hilbert à noyau auto-reproduisant (RKHS), noté H, qui est construit comme une somme directe d'espaces de Hilbert (Durrande et al. (2013)). L'estimateur du méta-modèle, noté f^, est calculé en minimisant un critère des moindres carrés pénalisé par la somme de la norme de Hilbert et de la norme empirique L2 (Huet and Taupin (2017)). Cette procédure, appelée RKHS ridge groupe sparse, permet à la fois de sélectionner et d'estimer les termes de la décomposition de Hoeffding, et donc de sélectionner les indices de Sobol non-nuls et de les estimer. Il permet d'estimer les indices de Sobol même d'ordre élevé, un point connu pour être difficile à mettre en pratique.Ce travail se compose d'une partie théorique et d'une partie pratique. Dans la partie théorique, j'ai établi les majorations du risque empirique L2 et du risque quadratique de l'estimateur f^ d'un modèle de régression où l'erreur est non-gaussienne et non-bornée. Il s'agit des bornes supérieures par rapport à la norme empirique L2 et à la norme L2 pour la distance entre le modèle m et son estimation f^ dans le RKHS H. Dans la partie pratique, j'ai développé un package R appelé RKHSMetaMod, pour la mise en œuvre des méthodes d'estimation du méta-modèle f∗ de m. Ce package s'applique indifféremment dans le cas où le modèle m est calculable et le cas du modèle de régression. Afin d'optimiser le temps de calcul et la mémoire de stockage, toutes les fonctions de ce package ont été écrites en utilisant les bibliothèques GSL et Eigen de C++ à l'exception d'une fonction qui est écrite en R. Elles sont ensuite interfacées avec l'environnement R afin de proposer un package facilement exploitable aux utilisateurs. La performance des fonctions du package en termes de qualité prédictive de l'estimateur et de l'estimation des indices de Sobol, est validée par une étude de simulationIn this work, the problem of estimating a meta-model of a complex model, denoted m, is considered. The model m depends on d input variables X1 , ..., Xd that are independent and have a known law. The meta-model, denoted f ∗ , approximates the Hoeffding decomposition of m, and allows to estimate its Sobol indices. It belongs to a reproducing kernel Hilbert space (RKHS), denoted H, which is constructed as a direct sum of Hilbert spaces (Durrande et al. (2013)). The estimator of the meta-model, denoted f^, is calculated by minimizing a least-squares criterion penalized by the sum of the Hilbert norm and the empirical L2-norm (Huet and Taupin (2017)). This procedure, called RKHS ridge group sparse, allows both to select and estimate the terms in the Hoeffding decomposition, and therefore, to select the Sobol indices that are non-zero and estimate them. It makes possible to estimate the Sobol indices even of high order, a point known to be difficult in practice.This work consists of a theoretical part and a practical part. In the theoretical part, I established upper bounds of the empirical L2 risk and the L2 risk of the estimator f^. That is, upper bounds with respect to the L2-norm and the empirical L2-norm for the f^ distance between the model m and its estimation f into the RKHS H. In the practical part, I developed an R package, called RKHSMetaMod, that implements the RKHS ridge group sparse procedure and a spacial case of it called the RKHS group lasso procedure. This package can be applied to a known model that is calculable in all points or an unknown regression model. In order to optimize the execution time and the storage memory, except for a function that is written in R, all of the functions of the RKHSMetaMod package are written using C++ libraries GSL and Eigen. These functions are then interfaced with the R environment in order to propose an user friendly package. The performance of the package functions in terms of the predictive quality of the estimator and the estimation of the Sobol indices, is validated by a simulation study
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Bárta, Miroslav. "Vliv atmosférických turbulencí na optický svazek." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218156.
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The aim of this thesis is to study a free space optics and its application in communication technologies. It describes possible interrupting impacts on the beamed optical signal, which are signal noise, attenuation of the atmosphere and atmospheric turbulence. The basis of the thesis is to describe the impact of the atmospheric turbulences on the optical beam. Fluctuation of optical intensity in the optical beam has been measured and index of refraction structure parameter calculated. With its assistance, turbulence rate has been determined.
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Boersma, Stuart F. "Parametric manifolds /." 1994. http://hdl.handle.net/1957/16810.
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"Parametric variation in architecture." 2010. http://library.cuhk.edu.hk/record=b5893963.
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Wong Chui Kwan, Alice."Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2009-2010, design report."
"May 2010."
Includes bibliographical references.
Chapter Sep-Dec 2009 // Part I --- Research and Experiment: Designing Parameter
Chapter i --- Introduction
What is parametric?
Critics & Doubts
Thesis Statement
Thesis Components
Chapter ii --- Theoretical Research
Terminology
Parametric
Parametric VARIATION
Parametric COMPLEXITY
range
correlation
ambiguity
Parametric Architecture
Parametric Benefits
"Logic, Factor & Parameter"
Levels ofVariation
Precedent Study
Parametric Tool
Rhinoceros Grasshopper
Tutorial Examples
Chapter iii --- Parametric Design Exercise
Parametric Machine
Parametric Mechanism
Interpretation into Design
GH scripting process
Chapter Jan-Apr 2010//Part II --- Architectural Project: Parametric Design
Chapter iv --- Architectural Project
Parametric House
Early Development
Drawings
Photos
Spatial Sequence (Perspective Collage)
Chapter v --- Special Study
Documentation of Design Making (Process & Methodology)
Site Condition vs Massing
Spatial Organization vs Differentiation Principle
Program Distribution vsView Openness
Chapter Xtra --- Thesis Abstract
Reference Article
Timeline Schedule
Presentation Materials
Sem I Posters
Sem II Posters
DLN Awards Special Studies - Shaping Cities
Grassopper Scripts (Snapshot)
Postface
Acknowledgment
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Lin, Ting-Yu, and 林庭羽. "A Study of Parametric Opening for Space." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07987530746878002472.
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碩士國立交通大學
建築研究所
100
The openings play a crucial role as far as space and inhabitant are concerned. The people can sense the space in the openings exist. The different openings present maybe let people sense the space experience is different. Architects express design thinking through the design of openings which moving with every period of design trends and tectonic developments have various presents. The digital design tools maturity made the opening form became more complex by the architecture appearance complexity. The algorithm application also promoted computer-aided design to toward advanced level (Shaghayegh & Jean-Claude, 2009; Bosia, 2011). Therefore, more and more designers realized the unique formal and organizational opportunities that are afforded via sophisticated parametric techniques (Schumacher, 2008). After that, the emergent interactive design influenced the current design thinking and techniques. Applying the interactive design technique to support presented the openings which can respond local Parametric design made openings appear novel forms, but sometimes the openings basic requirements had been lost. When the designers expend their opening design, they have to consider the factors of the openings about function, tectonic and form. This paper tried to search the parametric openings to cause the sense of space. Under the premise of include the factors of the openings about function, tectonic and form. The parametric method creates openings if achieve the sense of space. This paper discussed the important factors of function, tectonic and form about openings by last cases and the relationship with the sense of space and found the main factors of openings to influence the sense of space be created. Then, using the parametric opening design tool, Grasshopper, executed opening design implement to seek the methods about the parametric openings to create the sense of space. These feasible methods provided openings prototype by using parametric design tools. The research process includes three steps: Step 1. Induce openings factor, Step 2. Case study, Step 3.design implement。
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Chao, Yu-Lun, and 趙育倫. "The Rule Space Based On Non-parametric IRT." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/65100530603942442374.
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碩士國立台中師範學院
國民教育研究所
85
The Rule Space Based on Non-parametric IRT Yu-Lun Chao Abstract This study evaluates the performance of Tatsuoka''s rule spacebased on three-parameter item response theory and nonparametricitem response theory. The data of this study was collected form a random sample of4465 fifth grade students in Taiwan. In this study, seven testswere designed to measure the ability of subjects on the additionof fractions. Then, based on test result, the analysis of students The result of the study includes the following points:1. In discriminating the error patterns of students, rule space based on nonparametric IRT model performs better than rule space based on three-parameter IRT model.2. When the denominators of two fractions are different, the difficulty of fraction addition increases. And the more difference between the denominators, the higher the difficulty is.3. Fraction reduction is one of the major problems for students to solve fraction addition test items.4. From the analysis of test items based on their ICC''s, five different types of ICC are found. And, most of the test items'' ICCs show that the items have high discrimination power and adequate level of difficulty. At the end, the implications of the study on school teachingand the need of futrue research were also proposed.
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Wang, Yen-ching, and 王嬿晴. "Parametric Design and Digital Fabrication for Curved Space Frame." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/v35grq.
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碩士國立臺灣科技大學
建築系
99
The rapid development of digital technology has greatly influenced and revolutionized the architectural profession. Curvilinear building forms are becoming more commonplace and in recent years, many exemplary cases have emerged; however, most of them focus merely on the form and aesthetics, and less on building construction. Consequently, a huge gap between local construction techniques and digital design arises. In light of this, the research will investigate the development and construction of a curved truss system to evaluate the potential revolutionary impacts of digital technology on existing building construction techniques. A "Case Based Design" method is used for form finding of the free-form surface. After establishing the design objectives and requirements, the IBM Traveling Pavilion is selected as the initial case which can be used to improve the space truss system. The folding edge in the pyramid units will supersede the truss members and simplify the 3D joints. After various criticism and iterative adjustments, the project continued the form-finding process until all the design objectives were met. In the design and construction process Rhino-Grasshopper, a parametric design tool, utilized a digital manufacturing technique known as "folding” to make pyramid units. The pyramid units resolve the traditional standard space truss systems inability to create free-form surfaces and additionally, redefine the possibility of using a truss system to construct curvilinear forms. To simulate the feasibility of real-life applications and correct any defects, corrugated cardboard and a laser cutter for digital fabrication were used to make a reduced scaled model and a full scaled model. With the design manipulation during the construction process, and using practical experience to elaborate the procedures and methods of digital fabrication. Conclusively, the research reveals that by using a parametric program as a tool of tectonic development it is possible to successfully refine a traditional standard space truss system and establish an innovative construction method. From design to construction, this alternative process of digital tectonic manipulation is advantageous because it integrates structural techniques, construction and digital design and fabrication. All the working records, tectonic experience and relative questions mentioned can be a reference for all others that study digital architecture. KEYWORDS: curved surface, parametric, space truss
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Lin, Yu-chieh, and 林雨潔. "From Primitive to Parametric Hut:[Fabric Material]Relaxing in a Cocoon Space." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/u4csbx.
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碩士東海大學
建築學系
103
Fabric material The design starts from an image of a bamboo structure covered with linen fabric I found on the net. I really like the simple way they connect with bamboo and make it into a lotus form. With the white linen fabric, the simple structure an eye catching installation has been constructed. However, I start to think why people they never use fabric as a structure? Is it possible to use a soft piece of fabric and build a hut? In most of projects, fabric is only used to be a skin. In some of projects, fabric is used with parametric way to generate the form order. But in my thought, I think fabric has its own structure inside which is the knitting textile. It’s different from building structure. Moreover, fabric is our cloth. It’s very close to our body. Because it’s soft, it has potential to give us a new soft space experiences. This is the reason I chose fabric to be my material and started a series of experiments. Fabric Space Parametric Study Fabric doesn’t use a common supporting structure system. It’s more like a hanging system. A private cocoon space hanging in the air is the first idea in my thought. With the soft material surrounding around, the space is like a bed and everyone can go inside being relax. In this project, I want to make a fabric cocoon to be my parametric hut. Grasshopper helps me to think about how can I use “twist structure” to stable the cocoon space. As the twist fabric divides into more times, the fabric sticks will be thinner. In the end, I use grasshopper plug-in, kangaroo, to stimulate the fabric fettle.
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Kumar, Ashok. "Parametric processes of high power electromagnetic waves in laboratory and space plasmas." Thesis, 2008. http://localhost:8080/iit/handle/2074/4269.
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Liao, Pei-chen, and 廖姵宸. "Artifact as a Platform of Parametric Convergence and Interchange: Object, Container and Space." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/35350035035149752669.
Full textAbstract:
碩士國立雲林科技大學
建築與室內設計系碩士班
99
All things that can be perceived must have their attributes. Any perceived attributes can be parameterized. Once the attributes of artifacts are adjusted by human beings, their parameters also are manipulated. The artifacts are created after many considerations from diverse viewpoints. Therefore, artifacts converge with the parameters from those viewpoints through creation processes. Thus, artifact can be regarded as a platform of converging and interchanging numerous parameters. This research begins with an analysis of bow and arrow to understand the parametric relationship between parts composing an object, and the relationship between designer and design object. Then the study gradually deduces to the parametric relationship between object and its container, and the parametric relationship between container and space. Based on three levels of analysis, the parametric feature, the relationship and the framework of an artifact, as well as the parametric framework and linkage of artifacts of different hierarchy are investigated. This research demonstrates two-level design of furniture and interior in terms of diagrams to investigate the adjustments of various parameters in design process. This research attempts to connect the idea of parametric design to the material world, and make parametric design not only a presentation of virtual form, but a way of interpreting and creating artifacts in the reality.
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Tsai, Min-Shi, and 蔡敏仕. "An Exploration of Light and Shadow Series in the Space through Parametric Design." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/46881490624738148018.
Full textAbstract:
碩士淡江大學
建築學系碩士班
104
This research discusses how to utilize parametric design to construct light and shadow for space, to generate variations of the environment through parametric patterns and structures, to create environmental atmosphere and stimulates users’ vision. Light and shadow sequences keep on changing in different periods and directions according to various rules, orders of space can be observed through the arranged light and shadow sequence. Just like Roman’s Pantheon, interaction with the natural environment can be seen through the window on the top of the building. Therefore, atmospheres of spaces can be derived from different angles of sunshine in different periods. This research includes four parts. The first two parts are the method and process for searching related design for this study. The first part is survey of the uses light and shadow in architecture. We can see the interaction between light and space from experiences. Then the discussions of transparency and OP art enlighten the viewpoint and imagination of this research. Finally, it discusses relationships of spatial light and shadow sequence, to extend subsequent research through the enlightened viewpoints. The second part of this research includes the studies of artistic work and spatial method of light. It utilizes case studies related to transparency to think over the relationship between environment and building, and how to construct light and shadow space through building design method. OP art brings simulation for our visual senses, and plan geometric figures create various optical illusions to convey ideas of through combinations and permutations. Moreover, OP artists of different styles find out applicable design principles and can be extended for the design methods of this study. The last two parts of this research include applications for the design method and parametric design of the light and shadow. The third part derives and parameterizes the design through the studies of six OP artists’ works. During the process of literature reviews, this research learns how to design parametric permutation and combination, to find out different parameters and give proper values to represent visual effects. After the rules are derived, it analyzes applicable building design method and combines with environment to generate spatial light and shadow. The fourth part verifies the design method. It first tries to make extensional design for an existing building. The site is Taipei Fine Arts Museum with the structure designs inspired by OP art. It utilizes design methods from various OP arts to create interaction between audiences and structures, to stimulate visual effects of light through the movement of people. Finally, is architectural design, to design on four sites for different building functions, there are station, extreme playground, bridge and pavilion square. The final process of architectural design for this study adjusts different design parameters slightly causes the different conclusions for spatial relationships of light and shadow. Through the parameterizations for light and shadow, multiple spatial atmospheres can be realized.