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Bui, Van Bien. "La stabilité du filtre non-linéaire en temps continu." Thesis, Nice, 2016. http://www.theses.fr/2016NICE4002/document.
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Le problème de filtrage consiste à estimer l'état d'un système dynamique, appelé signal qui est souvent un processus markovien, à partir d'observation bruitées des états passés du système. Dans ce mémoire, nous considérons un modèle de filtrage en temps continu pour le processus de diffusion. Le but est d'étudier la stabilité du filtre optimal par rapport à sa condition initiale au-delà de l'hypothèse de mélange (fort) pour le noyau de transition en ignorant l'ergodicité du signalThe filtering problem consists of estimating the state of a dynamic, called signal which is often a Markov process, from the noisy observation of the past states. In this thesis, we consider a filtering model in continuous time for the diffusion process. The aim is to study the stability of the optimal filter with respect to its initial condition beyond the mixing (or quasi – mixing) hypothesis for the transition kernel
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Morzfeld, Matthias, Daniel Hodyss, and Chris Snyder. "What the collapse of the ensemble Kalman filter tells us about particle filters." TAYLOR & FRANCIS LTD, 2017. http://hdl.handle.net/10150/623125.
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The ensemble Kalman filter (EnKF) is a reliable data assimilation tool for high-dimensional meteorological problems. On the other hand, the EnKF can be interpreted as a particle filter, and particle filters (PF) collapse in high-dimensional problems. We explain that these seemingly contradictory statements offer insights about how PF function in certain high-dimensional problems, and in particular support recent efforts in meteorology to 'localize' particle filters, i.e. to restrict the influence of an observation to its neighbourhood.
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Law, Ying Man. "Iterative algorithms for the constrained design of filters and filter banks /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20LAW.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 108-111). Also available in electronic version. Access restricted to campus users.
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Ravet, Alexandre. "Introducing contextual awareness within the state estimation process : Bayes filters with context-dependent time-heterogeneous distributions." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0045/document.
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Ces travaux se focalisent sur une problématique fondamentale de la robotique autonome: l'estimation d'état. En effet, la plupart des approches actuelles permettant à un robot autonome de réaliser une tâche requièrent tout d'abord l'extraction d'une information d'état à partir de mesures capteurs bruitées. Ce vecteur d'état contient un ensemble de variables caractérisant le système à un instant t, comme la position du robot, sa vitesse, etc. En robotique comme dans de nombreux autres domaines, le filtrage bayésien est devenu la solution la plus populaire pour estimer l'état d'un système de façon robuste et à haute fréquence. Le succès du filtrage bayésien réside dans sa relative simplicité, que ce soit dans la mise en oeuvre des équations récursives de filtrage, ou encore dans la représentation simplifiée et intuitive du système au travers du modèle de Markov caché d'ordre 1. Généralement, un filtre bayésien repose sur une description minimaliste de l'état du système. Cette représentation simplifiée permet de conserver un temps d'exécution réduit, mais est également la conséquence de notre compréhension partielle du fonctionnement du système physique. Tous les aspects inconnus ou non modélisés du système sont ensuite représentés de façon globale par l'adjonction de composantes de bruit. Si ces composantes de bruit constituent une représentation simple et unifiée des aspects non modélisés du système, il reste néanmoins difficile de trouver des paramètres de bruit qui sont pertinents dans tous les contextes. En effet, à l'opposé de ce principe de modélisation, la problématique de navigation autonome pose le problème de la multiplicité d'environnements différents pour lesquels il est nécessaire de s'adapter intelligemment. Cette problématique nous amène donc à réviser la modélisation des aspects inconnus du systèmes sous forme de bruits stationnaires, et requiert l'introduction d'une information de contexte au sein du processus de filtrage. Dans ce cadre, ces travaux se focalisent spécifiquement sur l'amélioration du modèle état-observation sous-jacent au filtre bayésien afin de le doter de capacités d'adaptation vis-à-vis des perturbations contextuelles modifiant les performances capteurs. L'objectif principal est donc ici de trouver l'équilibre entre complexité du modèle et modélisation précise des phénomènes physiques représentés au travers d'une information de contexte. Nous établissons cet équilibre en modifiant le modèle état-observation afin de compenser les hypothèses simplistes de bruit stationnaire tout en continuant de bénéficier du faible temps de calcul requis par les équations récursives. Dans un premier temps, nous définissons une information de contexte basée sur un ensemble de mesures capteurs brutes, sans chercher à identifier précisément la typologie réelle de contextes de navigation. Toujours au sein du formalisme bayésien, nous exploitons des méthodes d'apprentissage statistique pour identifier une distribution d'observation non stationnaire et dépendante du contexte. cette distribution repose sur l'introduction de deux nouvelles composantes: un modèle destiné à prédire le bruit d'observation pour chaque capteur, et un modèle permettant de sélectionner un sous-ensemble de mesures à chaque itération du filtre. Nos investigations concernent également l'impact des méthodes d'apprentissage: dans le contexte historique du filtrage bayésien, le modèle état-observation est traditionnellement appris de manière générative, c'est à dire de manière à expliquer au mieux les paires état-observation contenues dans les données d'apprentissage. Cette méthode est ici remise en cause puisque, bien que fondamentalement génératif, le modèle état-observation est uniquement exploité au travers des équations de filtrage, et ses capacités génératives ne sont donc jamais utilisées[...]Prevalent approaches for endowing robots with autonomous navigation capabilities require the estimation of a system state representation based on sensor noisy information. This system state usually depicts a set of dynamic variables such as the position, velocity and orientation required for the robot to achieve a task. In robotics, and in many other contexts, research efforts on state estimation converged towards the popular Bayes filter. The primary reason for the success of Bayes filtering is its simplicity, from the mathematical tools required by the recursive filtering equations, to the light and intuitive system representation provided by the underlying Hidden Markov Model. Recursive filtering also provides the most common and reliable method for real-time state estimation thanks to its computational efficiency. To keep low computational complexity, but also because real physical systems are not perfectly understood, and hence never faithfully represented by a model, Bayes filters usually rely on a minimum system state representation. Any unmodeled or unknown aspect of the system is then encompassed within additional noise terms. On the other hand, autonomous navigation requires robustness and adaptation capabilities regarding changing environments. This creates the need for introducing contextual awareness within the filtering process. In this thesis, we specifically focus on enhancing state estimation models for dealing with context-dependent sensor performance alterations. The issue is then to establish a practical balance between computational complexity and realistic modelling of the system through the introduction of contextual information. We investigate on achieving this balance by extending the classical Bayes filter in order to compensate for the optimistic assumptions made by modeling the system through time-homogeneous distributions, while still benefiting from the recursive filtering computational efficiency. Based on raw data provided by a set of sensors and any relevant information, we start by introducing a new context variable, while never trying to characterize a concrete context typology. Within the Bayesian framework, machine learning techniques are then used in order to automatically define a context-dependent time-heterogeneous observation distribution by introducing two additional models: a model providing observation noise predictions and a model providing observation selection rules.The investigation also concerns the impact of the training method we choose. In the context of Bayesian filtering, the model we exploit is usually trained in the generative manner. Thus, optimal parameters are those that allow the model to explain at best the data observed in the training set. On the other hand, discriminative training can implicitly help in compensating for mismodeled aspects of the system, by optimizing the model parameters with respect to the ultimate system performance, the estimate accuracy. Going deeper in the discussion, we also analyse how the training method changes the meaning of the model, and how we can properly exploit this property. Throughout the manuscript, results obtained with simulated and representative real data are presented and analysed
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Bourrous, Soleiman. "Étude du colmatage des filtres THE plans et à petits plis par des agrégats de nanoparticules simulant un aérosol de combustion." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0301/document.
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Dans les installations nucléaires, les particules en suspension sont le vecteur d’une grande partie de la contamination radiologique. Pour cette raison, l'IRSN (Institut de Radioprotection et de Sûreté Nucléaire) étudie les filtres THE (Très Haute Efficacité) plissés qui sont l'un des dispositifs permettant assurer la sécurité de l'exploitation nucléaire. Pour éviter les rejets dans l'environnement, la compréhension du comportement des filtres en particulier dans la situation accidentelle doit être aussi exhaustive que possible. L'accident le plus probable et le plus pénalisant pour les dispositifs de confinement est l’incendie qui conduit à une production massive de particules de suie. Dans ce cas, le colmatage des filtres est un problème qui doit être pris en compte. Jusqu'à présent, une corrélation empirique a été développée pour prédire l'augmentation de perte de charge. Toutefois, le caractère empirique de cette corrélation ne permet pas son utilisation dans toutes les situations. Une compréhension phénoménologique et un modèle de colmatage est alors nécessaire. Le travail de thèse qui suit vise à lier l'évolution de la perte de charge à des observations physiques pour chaque étape du colmatage. Pour ce faire, l'étude a été divisée en deux parties. La première se focalise sur le comportement du filtre plan en mesurant la pénétration de particules à l'intérieur du medium et la porosité du dépôt formé sur sa surface. La deuxième partie consiste en une expérience à petite échelle basée sur un seul pli. L'accumulation de particules à l'intérieur du pli a été directement observée, de plus, la déformation du pli ainsi que les écoulements d'air dans le pli (en utilisant une méthode de PIV) ont été mesurés. Au cours de ces expériences, la perte de charge a été mesurée et les paramètres mesurés ont été liés à l'évolution de la perte de charge. La finalité est de construire un modèle analytique simple afin de prédire l'évolution de la perte de charge des filtres en fonction de la masse déposée, des caractéristiques de l'aérosol et des conditions aérauliques. La principale perspective ouverte par ces résultats est la validation des modèles numériques complets pour surmonter les limites expérimentales. Le prolongement logique de ce travail sera l'étude du comportement d'un filtre colmaté soumis à des contraintes de température, d’humidité et aux agressions chimiques de produits de combustionIn nuclear facilities, airborne particles are the vector of most of the radiological contamination. For this reason, pleated HEPA filters are one of the containment devices which are actively studied by the IRSN (Institut de Radioprotection et de Sûreté Nucléaire) to ensure the safety of nuclear exploitation. To avoid contamination of the environment, the understanding of the behavior of the filters especially in accidental situation has to be as exhaustive as possible. The most probable accident and the most penalizing for the containment devices is fire which leads to a massive soot particle production. In this case, the clogging of the filters is a problematic which has to be taken into account. Up to now, an empirical correlation has been developed to predict the pressure drop increase. The empirical nature of this correlation doesn’t allow its use in all situations. A phenomenological understanding and model of the clogging is then necessary. The following PhD work aims to reduce the pressure drop evolution to physical observations for each step of the clogging in order to model it on the most physical basis as possible. To do so, the study has been divided in two parts. The first one focusing on the behavior of flat filter by measuring the penetration of particles inside the medium and the porosity of the deposit formed on its surface. In the second part a small scale experiment based on a single pleat has been developed. Accumulation of the particles inside the pleat has been directly observed, deformation of the pleat as well as airflow in the pleat (using a PIV method) has been measured. During these experiments, pressure drop has been monitored and the measured parameters have been linked to the pressure drop evolution. Finality is to build a simple analytical model to predict the pressure drop evolution of the filters as a function of the deposited mass, the aerosol characteristics and the ventilation conditions. The main perspective opened by these results is the validation of complete numerical models to overcome the experimental limits. The logical extension of this work will be the study of the interaction of a clogged filter with temperature, air moisture and chemical aggression
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Iyer, Naresh Sundaram. "A Family of Dominance Filters for Multiple Criteria Decision Making: Choosing the Right Filter for a Decision Situation." Connect to this title online, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1005939267.
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Thesis (Ph. D.)--Ohio State University, 2001.Title from first page of PDF file. Document formatted into pages; contains xiv, 169 p.; also contains graphics (some col.). Includes abstract and vita. Advisor: B. Chandresekaran, Dept. of Computer and Information Science. Includes bibliographical references (p. 165-169).
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Boudreau, Chantal. "The transport of radioactive ions in a gas filled radio frequency quadrupole mass filter system /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32979.
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The technique of ion transfer in radio frequency quadrupole (RFQ) systems is described. Computer simulations of the gas filled RFQ mass filter system located at Argonne National Laboratory (ANL) in Argonne, Il. are performed and compared to data obtained from the transfer of radioactive ions produced from the fragmentation of an off-line 252Cf fission source put before the system. The device is used to transport radionuclides created in on-line fusion evaporation reactions from a 150 torr helium filled gas cell to a high vacuum mass spectrometer. Operation parameters and performance results for the gas filled RFQ mass filter system are presented. In addition, the first on-line transfer of a radioisotope resulting in a precise mass measurement using the Canadian Penning Trap (CPT) mass spectrometer is discussed.
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Andersson, Egerlid Axel, and Fredrik Westin. "Design of filter cloth analyser : Development of a portable filter cloth selection tool for filters used to regenerate the acid used in the pickling process during the production of stainless steel." Thesis, Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71474.
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The stainless steel industry is an industry which manufactures one of the most used ma-terials in the world. Even though the vast size of the industry many might not reflect werethe steel comes from when buying their IKEAcutlery etc. But in fact this industry is moreintricate and complex than one might think.During the manufacturing process, the steelgoes through several processes. One of thoseprocesses is done by treating the steel withstrong acid. This chemical process is calledpickling. The pickling process is what createsthe characteristic smooth and shiny surface ofa product made in stainless steel.This thesis is about the development of a testunit that is able to effectively test the ASRA(Acid Sludge Removal Apparatus) filter cloths.The ASRA is a filtration system developed by Scanacon in Stockholm that filtrates and puri-fies acid that is used during the pickling pro-cess of a steel manufacture process. Today, it is complicated, time consuming and dangerous totest and evaluate different filter cloths in orderto find the cloth that provides the best result,since the tests has to be conducted on the realsystems. The aim of this thesis was therefore tosolve these problems. Scanacon wanted to findan alternative solution, that would not includeinteraction with the real filtration system. Theyalso wanted a portable and safe solution. To solve the problem a iterative design pro-cess called RDCD which stands for research, design, create & delivery was developed. Theprocesses was heavily influenced by the CDIO process (Conceive, Design, Implement & Ope-rate). After the research phase was conducted it was decided that a small filter analysis productwould be the best way to solve the problem. The product was then developed one com-ponent at a time. During the project several prototypes and test was created and conductedin order to validate the design.The result is a small filtration unit speciallydesigned to simulate the ASRA system. Theproduct is able to rapidly test various filtercloths in an easy way, without putting the user in harm’s way. After the tests has been perfor-med can the user can identify which cloth that worked the best. The product is small enoughto be possible to be carried in a hard case bag,which in turn affords portability.Stålindustrin är en industri som tillverkar ettav de mest använda materialen i världen. Trotsindustrins enorma storlek är det kanske intemånga som reflekterar varifrån stålet kommerifrån när man köper exempelvis IKEA bestick.Men faktum är att den här industrin är mycketmer invecklad och komplex än vad man kan tro. Under tillverkningsprocessen går stålet ige-nom flera processer. En av de här processerna genomförs genom att behandla stålet med starksyra. Den kemiska processen kallas för betningoch är det som ger en produkt tillverkad i stålden karaktäristiska lena och glänsande ytan. Den här examensrapporten handlar om ut-vecklandet av en test enhet som effektivt kan testa filter dukarna till ASRA (Acid SludgeRemoval Apparatus) systemet. ASRA systemetär ett filtreringssystem utvecklat av Scanaconi Stockholm som filtrerar och renar syran som används under betningsprocessen vid stål-tillverkning. Idag är det komplicerat, tidskrä-vande och farligt att testa och utvärdera olika filterdukar för att ta reda på vilken duk somger bäst resultat, eftersom att testerna måstegenomföras på de riktiga systemen. Målet fördet här examensarbetet var därför att lösa dehär problemen. Scanacon ville ha en alternativlösning som inte kräver interaktion med deriktiga systemen. De ville också ha en portabeloch säker lösning. För att lösa problemet utvecklades en itera-tiv designprocess kallad RDCD som står för research, design, create & delivery. Processen var tungt influerat av CDIO (Conceive, De-sign, Implement & Operate) processen. Efter att researchfasen var genomförd bestämdesdet att en liten filteranalysatorprodukt var detbästa sättet att lösa problemet på. Produktenutvecklades sedan en komponent i taget. Underprojektets gång har flera prototyper byggts och flera tester genomförts för att validera designen. Resultatet är en liten filtreringsenhet som är specialdesignad för att simulera ASRA syste-met. Produkten kan snabbt testa oliak filterdu-kar på ett enkelt sätt, utan utsätta användaren för fara. Efter att testerna genomförts kananvändaren identifiera vilken duk som funkatbäst. Produkten är tillräckligt liten för att fåplats i en hårdplast väska, vilket ger produktenden efterfrågade portabiliteten.
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Kruger, Abraham J. "The impact of filter loading on residential hvac performance." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50344.
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Buildings are the primary user of energy in the USA. Within homes, the heating, ventilation, and air condition (HVAC) system is the largest energy consumer. This study: (i) developed a new methodology for simulating filter loading in-situ; (ii) observed the impact of filter loading on AC performance in-situ; and (iii) provided a greater understanding of when a filter is “dirty” and should be replaced. Six central AC systems in the Atlanta metro-region were evaluated. Filter loading was simulated by installing the TrueFlow® airflow metering device and partially taping off the face at 3 different increments. This resulted in measurements at 5 discrete static pressures (no filter, TrueFlow, TrueFlow Taped one, TrueFlow Taped two, and TrueFlow Taped three). The pilot study found that as filter pressure drop increased, airflow rates generally decreased, resulting in higher differences in temperature across the evaporator coil (∆T). There was no observed correlation between absolute humidity across the evaporator coil and either filter pressure drop or system airflow. Overall, as airflow decreased so did sensible, latent, and total capacity. This research can inform decisions about filter replacement and be used to evaluate computer simulation models of HVAC performance.
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Zubi, Hazem. "Lowpass Broadband Harmonic Filter Design." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606587/index.pdf.
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In this thesis an analytical design method of the improved broadband passive harmonic filter (IBF) for three phase diode rectifier front-end type adjustable speed drives is presented. The method is based on frequency domain modeling of the rectifier and filter. The success of the method involves accurate representation of the load harmonics. With the harmonics well defined, the harmonic and fundamental frequency equivalent circuits are utilized to analytically calculate the voltages/currents. Thus, the size and the performance of the filter can be optimized. The analytical method is verified via computer simulations and laboratory experiments.
Also a performance comparison of various passive harmonic filters for three-phase diode rectifier front-end type adjustable speed drives is provided. The comparison involves the input current total harmonic distortion, input power factor, rectifier voltage regulation, energy efficiency, size, and cost. The parallel/series harmonic resonance problem related issues are addressed and unbalanced operation performance investigated. The comparison is based on analysis and computer simulations and the results are validated by laboratory experiments.
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Bamberger, Roberto Hugo. "The directional filter bank : a multirate filter bank for the directional decomposition of images." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/15346.
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Pellett, Andrew. "The Extended Kalman-Consensus Filter." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/PellettA2011.pdf.
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Burns, Donald Matthew. "The imperfect quadrupole mass filter." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400181.
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Vascimini, Vincent G. "Simulations Using the Kalman Filter." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1576685726771127.
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Farchi, Alban. "On the localisation of ensemble data assimilation methods." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1034.
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L’assimilation de données est la discipline permettant de combiner des observations d’un système dynamique avec un modèle numérique simulant ce système, l'objectif étant d'améliorer la connaissance de l'état du système. Le principal domaine d'application de l'assimilation de données est la prévision numérique du temps. Les techniques d'assimilation sont implémentées dans les centres opérationnels depuis plusieurs décennies et elles ont largement contribué à améliorer la qualité des prédictions. Une manière efficace de réduire la dimension des systèmes d'assimilation de données est d'utiliser des méthodes ensemblistes. La plupart de ces méthodes peuvent être regroupées en deux classes~: le filtre de Kalman d'ensemble (EnKF) et le filtre particulaire (PF). Le succès de l'EnKF pour des problèmes géophysiques de grande dimension est largement dû à la localisation. La localisation repose sur l'hypothèse que les corrélations entre variables d'un système dynamique décroissent très rapidement avec la distance. Dans cette thèse, nous avons étudié et amélioré les méthodes de localisation pour l'assimilation de données ensembliste. La première partie est dédiée à l'implémentation de la localisation dans le PF. Nous passons en revue les récents développements concernant la localisation dans le PF et nous proposons une classification théorique des algorithmes de type PF local. Nous insistons sur les avantages et les inconvénients de chaque catégorie puis nous proposons des solutions pratiques aux problèmes que posent les PF localisés. Les PF locaux sont testés et comparés en utilisant des expériences jumelles avec des modèles de petite et moyenne dimension. Finalement, nous considérons le cas de la prédiction de l'ozone troposphérique en utilisant des mesures de concentration. Plusieurs algorithmes, dont des PF locaux, sont implémentés et appliqués à ce problème et leurs performances sont comparées.La deuxième partie est dédiée à l'implémentation de la localisation des covariances dans l'EnKF. Nous montrons comment la localisation des covariances peut être efficacement implémentée dans l'EnKF déterministe en utilisant un ensemble augmenté. L'algorithme obtenu est testé au moyen d'expériences jumelles avec un modèle de moyenne dimension et des observations satellitaires. Finalement, nous étudions en détail la cohérence de l'EnKF déterministe avec localisation des covariances. Une nouvelle méthode est proposée puis comparée à la méthode traditionnelle en utilisant des simulation jumelles avec des modèles de petite dimensionData assimilation is the mathematical discipline which gathers all the methods designed to improve the knowledge of the state of a dynamical system using both observations and modelling results of this system. In the geosciences, data assimilation it mainly applied to numerical weather prediction. It has been used in operational centres for several decades, and it has significantly contributed to the increase in quality of the forecasts.Ensemble methods are powerful tools to reduce the dimension of the data assimilation systems. Currently, the two most widespread classes of ensemble data assimilation methods are the ensemble Kalman filter (EnKF) and the particle filter (PF). The success of the EnKF in high-dimensional geophysical systems is largely due to the use of localisation. Localisation is based on the assumption that correlations between state variables in a dynamical system decrease at a fast rate with the distance. In this thesis, we have studied and improved localisation methods for ensemble data assimilation.The first part is dedicated to the implementation of localisation in the PF. The recent developments in local particle filtering are reviewed, and a generic and theoretical classification of local PF algorithms is introduced, with an emphasis on the advantages and drawbacks of each category. Alongside the classification, practical solutions to the difficulties of local particle filtering are suggested. The local PF algorithms are tested and compared using twin experiments with low- to medium-order systems. Finally, we consider the case study of the prediction of the tropospheric ozone using concentration measurements. Several data assimilation algorithms, including local PF algorithms, are applied to this problem and their performances are compared.The second part is dedicated to the implementation of covariance localisation in the EnKF. We show how covariance localisation can be efficiently implemented in the deterministic EnKF using an augmented ensemble. The proposed algorithm is tested using twin experiments with a medium-order model and satellite-like observations. Finally, the consistency of the deterministic EnKF with covariance localisation is studied in details. A new implementation is proposed and compared to the original one using twin experiments with low-order models
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Fowler, Grant E. "Assessing the role of filler atoms in skutterudites and synthesis and characterization of new filled skutterudites." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001708.
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Tauban, Mathieu. "Impact of Filler Morphology and Distribution on the Mechanical Properties of Filled Elastomers : theory and simulations." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1069/document.
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Les nanocomposites présentent des propriétés uniques dont l'origine est sujette à débat. Dans ce travail, nous cherchons à déterminer quel est l'impact de la morphologie de la charge et de son état de distribution sur les propriétés des matériaux. Pour cela, nous avons étendu un modèle théorique que nous résolvons numériquement.Nous avons étudié l'effet de la distribution des charges dans la matrice. Nous montrons qu'un état de distribution fortement hétérogène conduit à un renforcement plus important qui s'étend dans une plus large gamme de températures, mais augmente aussi la dissipation d'énergie. Ensuite, nous étudions l'effet de la structure des charges. Des particules parfaitement sphériques sont comparées à des agrégats fractals plus ou moins finement définis. Nous montrons que des objets finement définis peuvent s'imbriquer au sein de la matrice et conduisent à une augmentation du renfort et de la dissipation dans ces matériaux.Puis, nous étudions la réponse de nos systèmes lorsqu'ils sont soumis à une première élongation de forte amplitude. Nous montrons alors qu'un système hétérogène se plastifie localement progressivement au cours de la déformation alors qu'un système homogène présente une plastification catastrophique généralisée à partir d'une déformation critique. Enfin dans une dernière partie nous évaluons la possibilité d'étendre le modèle afin de simuler l'endommagement des nanocomposites. Nous introduisons pour cela un critère rupture local afin de prendre en compte l'endommagement du polymère entre les charges. Nous étudions ensuite comment se comportent les matériaux simulés en faisant varier la morphologie de la charge, son état de distribution et son taux.Ce travail constitue la première étude systématique de l'effet de la morphologie et de la distribution des charges sur les propriétés mécaniques des nanocomposites. Nous montrons que ces paramètres peu contrôlés sont pourtant des paramètres clés et peuvent servir à optimiser les propriétés d’usage d'un nanocompositeNano-filled elastomer composites are used in a very broad range of applications such as tires, damping materials and impact modifiers. The addition of nanoscale rigid particles in a polymer matrix induces nonlinear effects that are not yet fully understood far above the glass transition temperature of the pure matrix. A model of the reinforcement of nanocomposites based on the reduced mobility of the polymer confined between two spherical filler particles has been developed over the last ten years. In order to study the influence of the filler shape, structure, size, and dispersion state, we have extended the model were the morphology of the fillers is defined explicitly as spherical particles aggregated in the polymer matrix. The model is then solved by mesoscale numerical simulation in order to describe the mechanical properties of the nanocomposite. We study the mechanical response of nanocomposite filled with aggregates of different shapes and distribution state to deformations of various amplitudes in the reinforcement regime. We show that the mechanical behavior of nanocomposites strongly depends on the filler morphology and we propose that stress-relaxation mechanisms in the material are related to the disorder (particle size, aggregation number, distribution state) in the filler population. In a second part of this work, we study the mechanical response at larger amplitude in both a non-destructive and destructive regime. For that matter, the model has been extended in order to account for damaging of the polymer between filler particles.Our model opens the path for the development of systems with tailored properties by adjusting the fillers morphology and distribution
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Melgarejo, Lermas Juan Carlos. "Advanced Techniques for the Design and Optimization of Multi-Band and Reconfigurable Microwave Waveguide Filters." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/172728.
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[ES] El creciente número de dispositivos intercambiando datos ha empujado a las empresas del sector espacial a utilizar bandas de frecuencia cada vez más altas, como Ku, K y Ka, ya que permiten emplear canales de frecuencia más anchos. A medida que disminuye la longitud de onda, el tamaño de los filtros se reduce y, por tanto, son más sensibles a las desviaciones de fabricación. Para compensar estos errores, es necesario emplear elementos de sintonía en la etapa de diseño.
En este contexto presentamos una estrategia de diseño que permite incluir todos los factores no ideales, como elementos de sintonía o esquinas redondeadas, en las simulaciones finales de filtros y multiplexores.
Una vez se han fabricado los filtros es necesario ajustar manualmente los elementos de sintonía hasta recuperar la respuesta objetivo. Sin embargo, para realizar esta tarea con éxito es necesario tener mucha experiencia previa y, aún así, conlleva un tiempo considerable. Por tanto, también proponemos un procedimiento de sintonización eficiente y sistemático que permite a cualquier persona, independientemente de su experiencia previa en sintonización, realizar esta tarea con éxito.
Además del aumento de las tasas de transmisión, otros desafíos del sector espacial son reducir el tamaño y peso de sus componentes, así como dotarlos de capacidad dereconfiguración. Emplear dispositivos multifunción como filtros multibanda o dispositivos reconfigurables es una posible solución. En este contexto, proponemos una nueva familia de filtros multibanda en guía de ondas que puede adaptarse a las futuras necesidades del sector espacial. Con el mismo objetivo, también proponemos una familia de dispositivos reconfigurables de varios estados discretos que pueden modificar su comportamiento de forma remota.[CA] El creixent nombre de dispositius intercanviant dades ha empés a les empreses del sector espacial a utilitzar bandes de freqüència cada vegada més altes, com Ku, K i Ka, ja que permeten fer servir canals de freqüència més amples. A mesura que la longitud d'ona disminueix, la mida dels filtres es redueix i, per tant, són més sensibles a les desviacions de fabricació. Per compensar aquests errors, és necessari fer servir elements de sintonia en l'etapa de disseny. En aquest context presentem una estratègia de disseny que permet incloure tots els factors no ideals, com a elements de sintonia o cantonades arrodonides, en les simulacions finals de filtres i multiplexors. Una vegada s'han fabricat els filtres és necessari ajustar manualment els elements de sintonia fins a recuperar la resposta objectiu. Però, per realitzar aquesta tasca amb èxit és necessari tenir molta experiència prèvia i, així i tot, comporta un temps considerable. Per tant, també proposem un procediment de sintonització eficient i sistemàtic que permet a qualsevol persona, independentment de la seua experiència prèvia en sintonització, realitzar aquesta tasca amb èxit. A més de l'augment de les taxes de transmissió, altres desafiaments de el sector espacial són reduir la mida i pes dels seus components, així com dotar-los de capacitat de reconfiguració. Emprar dispositius multifunció com filtres multibanda o dispositius reconfigurables és una possible solució. En aquest context, proposem una nova família de filtres multibanda en guia d'ones que pot adaptar-se a les futures necessitats del sector espacial. Amb el mateix objectiu, també proposem una família de dispositius reconfigurables de diversos estats discrets que poden modificar el seu comportament de forma remota.
[EN] The need for ever increasing data rate of modern communication systems has motivated companies in the space sector to exploit higher frequency bands, such as Ku, K and Ka, in order to offer wider bandwidths to their customers. However, as the frequency increases, the wavelength decreases, and all waveguide hardware becomes smaller and more sensitive to deviations from the ideal dimensions that normally occur when manufacturing the devices. In order to compensate for these deviations (or errors), tuning elements must then be added to the hardware and included in the design process. In this context, therefore, we focus on the investigation of novel design strategies for filters and multiplexers with the objective of including all necessary non-ideal factors in the design process. It is important to note in this context that, once the filters are manufactured, the tuning elements are usually adjusted manually until the desired target performance has been achieved. However, successfully performing this task requires a considerable amount of time and very significant previous experience in tuning microwave filters. Consequently, an additional goal of our research work is to propose efficient and systematic tuning procedures so that anyone, regardless of their previous tuning experience, can successfully perform this difficult task. In addition to the increasing data rates, another current challenge of advanced communication systems is the ability to be reconfigured remotely to adjust to changes in costumer demands. The use of multi-function or reconfigurable devices is then an attractive possible solution. In this context, therefore, we also investigate new families of multi-band waveguide filters that can be used to accommodate several pass bands in the same filtering device. Furthermore, we also propose a new family of reconfigurable devices with several discrete states that can be easily controlled remotely.
Melgarejo Lermas, JC. (2021). Advanced Techniques for the Design and Optimization of Multi-Band and Reconfigurable Microwave Waveguide Filters [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172728
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Zubi, Hazem M. "A genetic algorithm approach for three-phase harmonic mitigation filter design." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604881.
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In industry, adjustable speed drives (ASDs) are widely employed in driving AC motors for variable speed applications due to the high performance and high energy efficiency obtained in such systems. However, ASDs have an impact on the power quality and utilisation of AC power feeds by injecting current harmonics and causing resonances, additional losses, and voltage distortion at the point of common coupling. Due to these problems, electric power utilities have established stringent rules and regulations to limit the effects of this distortion. As a result, efficient, reliable, and economical harmonic mitigation techniques must now be implemented in practical systems to achieve compliance at reasonable cost. A variety of techniques exist to control the harmonic current injected by ASDs, and allow three-phase AC-line-connected medium-power systems to meet stringent power quality standards. Of these, the broadband harmonic passive filter deserves special attention because of its good harmonic mitigation and reactive power compensation abilities, and low cost. It is also relatively free from harmonic resonance problems, has relatively simple structural complexity and involves considerably less engineering effort when compared to systems of single tuned shunt passive filters or active filters and active rectifier solutions. In this thesis, passive broadband harmonic filters are investigated. In particular, the improved broadband filter (IBF) which has superior overall performance and examples of its application are increasing rapidly. During this research project, the IBF operating principle is reviewed and its design principles are established. As the main disadvantage of most passive harmonic filters is the large-sized components, the first proposed design attempts to optimize the size of the filter components (L and C) utilized in the existing IBF topology. The second proposed design attempts to optimize the number and then the size of filter components resulting in an Advanced Broadband passive Filter (ABF) novel structure. The proposed design methods are based on frequency domain modelling of the system and then using a genetic algorithm optimization technique to search for optimal filter component values. The results obtained are compared with the results of a linear searching approach. The measured performance of the optimal filter designs (IBF and ABF) is evaluated under different loading conditions with typical levels of background voltage distortion. This involves assessing input current total harmonic distortion, input power factor, rectifier voltage regulation, efficiency, size and cost. The potential resonance problem is addressed and the influence of voltage imbalance on performance is investigated. The assessment is based on analysis, computer simulations and experimental results. The measured performance is compared to various typical passive harmonic filters for three-phase diode rectifier front-end type adjustable speed drives. Finally, the broadband filter design’s effectiveness and performance are evaluated by involving them in a standard IEEE distribution network operating under different penetration levels of connected nonlinear total loads (ASD system). The study is conducted via detailed modelling of the distribution network and the linked nonlinear loads using computer simulations.
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Gebart, Joakim. "GPU Implementation of the Particle Filter." Thesis, Linköpings universitet, Reglerteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-94190.
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This thesis work analyses the obstacles faced when adapting the particle filtering algorithm to run on massively parallel compute architectures. Graphics processing units are one example of massively parallel compute architectures which allow for the developer to distribute computational load over hundreds or thousands of processor cores. This thesis studies an implementation written for NVIDIA GeForce GPUs, yielding varying speed ups, up to 3000% in some cases, when compared to the equivalent algorithm performed on CPU. The particle filter, also known in the literature as sequential Monte-Carlo methods, is an algorithm used for signal processing when the system generating the signals has a highly nonlinear behaviour or non-Gaussian noise distributions where a Kalman filter and its extended variants are not effective. The particle filter was chosen as a good candidate for parallelisation because of its inherently parallel nature. There are, however, several steps of the classic formulation where computations are dependent on other computations in the same step which requires them to be run in sequence instead of in parallel. To avoid these difficulties alternative ways of computing the results must be used, such as parallel scan operations and scatter/gather methods. Another area where parallel programming still is not widespread is the area of pseudo-random number generation. Pseudo-random numbers are required by the algorithm to simulate the process noise as well as for avoiding the particle depletion problem using a resampling step. In this thesis a recently published counter-based pseudo-random number generator is used.
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Hinchcliffe, Victoria. "The filter dimension is morita invariant." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505562.
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Wilkinson, Timothy David. "The binary phase only matched filter." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361684.
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Wintz, Nicholas J. "The Kalman filter on time scales." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Wintz_09007dcc806c8092.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 31, 2009) Includes bibliographical references (p. 146-149).
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Al-Bayaty, Hussein Kamal Anwer. "Novel methods of utilization, elimination, and description of the distortion power in electrical circuits." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/10646.
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Firstly, this thesis investigates the electrical power harmonics in an attempt to utilize harmonic current and its distortion power in a novel idea to reconvert the distortion power into useful power. This is done, in order to feed different DC or AC loads in single and three-phase power system by using passive or active filters and accordingly, develop a new topology of hybrid active power filter (HAPF). In addition, this circuit can be considered as a power factor corrector (PFC) because it reduces the total harmonic distortion (THD) and improves the power factor (PF). Secondly, this thesis works on a new design of active power factor correction (APFC) circuit presenting two circuits with the same design principle: the first design consists of two active switches without an external complex control circuit, while the second design contains a single active switch with an additional control circuit. The main contribution of this circuit is 98% reduction of the inductor's value used in the newly proposed PFC circuit in comparison with the conventional boost converter which may lead to a huge reduction in size, weight and the cost of the new PFC circuit. Also, the active switches depend on a carefully designed switching pattern that results in an elimination of the third order harmonic from the input source current which decreases the value of total current harmonic distortion (THDI) to (14%) and improves the input PF to (0.99). Consequently, the simplicity of the design without requiring a complex control circuit and without a snubber circuit plus the minimum size of inductor, gives the newly proposed circuit the superiority on other PFC circuits. Thirdly, this research aims to describe the distortion power through submitting two novel power terms called effective active power (Pef ) & reactive power (Qef ) terms with a new power diagram called Right-Angled Power Triangle (RAPT) Diagram. In addition, a novel de nition of total apparent power (St) has been submitted in order to illustrate the physical meaning of (St) in non-sinusoidal systems. The new RAPT Diagram is based on the orthogonality law and depends on geometrical summation to describe the relationship between different aspects (apparent-active-reactive) of power, and different components (total-fundamental distortion), drawing a bridge to connect the time domain with the frequency domain in a two-dimensional diagram.
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Furtner, Bernhard. "Abiotic and biotic factors in the nutrient solution and filter skin (Schmutzdecke) of slow filters integrated to closed hydoponic greenhouse : potential predictors for assessment of efficacy /." Alnarp : Department of Crop Science, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/10232320.pdf.
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Yeo, David. "Intuitive reasoning and the enhanced novelty filter." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0001/NQ27756.pdf.
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Vo, Paul Vuong. "Ensemble Kalman Filter on the Brugge Field." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for matematiske fag, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19374.
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The purpose of modeling a petroleum reservoir consists of finding the underlying reservoir properties based on production data, seismic and other available data. In recent years, progress in technology has made it possible to extract large amount of data from the reservoir frequently. Hence, mathematical models that can rapidly characterize the reservoir as new data become available gained much interest. In this thesis we present a formulation of the first order Hidden Markov Model (HMM) that fits into the description of a reservoir model under production. We use a recursive technique that gives the theoretical solution to the reservoir characterization problem. Further, we introduce the Kalman Filter which serves as the exact solution when certain assumptions about the HMM are made. However, these assumptions are not valid when describing the process of a reservoir under production. Thus, we introduce the Ensemble Kalman Filter (EnKF) which has been shown to give an approximate solution to the reservoir characterization problem. However, the EnKF is depending on multiple realizations from the reservoir model which we obtain from the reservoir production simulator Eclipse. When the number of realizations are kept small for computational purposes, the EnKF has been shown to possibly give unreliable results. Hence, we apply a shrinkage regression technique (DR-EnKF) and a localization technique (Loc-EnKF) that are able to correct the traditional EnKF. Both the traditional EnKF and these corrections are tested on a synthetic reservoir case called the Brugge Field. The results indicate that the traditional EnKF suffers from ensemble collapse when the ensemble size is small. This results in small and unreliable prediction uncertainty in the model variables. The DR-EnKF improves the EnKF in terms of root mean squared error (RMSE) for a small ensemble size, while the Loc-EnKF makes considerable improvements compared to the EnKF and produces model variables that seems reasonable.
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Alhajraf, Ali F. M. "The Kriged Kalman filter and its applications." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421422.
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Hiemstra, John David. "Robust Implementations of the Multistage Wiener Filter." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26714.
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The research in this dissertation addresses reduced rank adaptive signal processing, with specific emphasis on the multistage Wiener filter (MWF). The MWF is a generalization of the classical Wiener filter that performs a stage-by-stage decomposition based on orthogonal projections. Truncation of this decomposition produces a reduced rank filter with many benefits, for example, improved performance.
This dissertation extends knowledge of the MWF in four areas. The first area is rank and sample support compression. This dissertation examines, under a wide variety of conditions, the size of the adaptive subspace required by the MWF (i.e., the rank) as well as the required number of training samples. Comparisons are made with other algorithms such as the eigenvector-based principal components algorithm. The second area investigated in this dissertation concerns â soft stopsâ , i.e., the insertion of diagonal loading into the MWF. Several methods for inserting loading into the MWF are described, as well as methods for choosing the amount of loading. The next area investigated is MWF rank selection. The MWF will outperform the classical Wiener filter when the rank is properly chosen. This dissertation presents six approaches for selecting MWF rank. The algorithms are compared to one another and an overall design space taxonomy is presented. Finally, as digital modelling capabilities become more sophisticated there is emerging interest in augmenting adaptive processing algorithms to incorporate prior knowledge. This dissertation presents two methods for augmenting the MWF, one based on linear constraints and a second based on non-zero weight vector initialization. Both approaches are evaluated under ideal and perturbed conditions.
Together the research described in this dissertation increases the utility and robustness of the multistage Wiener filter. The analysis is presented in the context of adaptive array processing, both spatial array processing and space-time adaptive processing for airborne radar. The results, however, are applicable across the entire spectrum of adaptive signal processing applications.Ph. D.
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Merrill, Douglas Richard 1962. "Gain-bandwidth effects on the resonator filter." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291772.
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The purpose of this study is to analyze the resonator filter, and to determine the effects of gain-bandwidth on the dominant complex conjugate pole pair. Optimization methods are then used as a design tool to determine the compensation required to shift the dominant pole pair back to their original design locations. New design values resulting from the compensation are used for the final circuit. Simulations are run to verify that the new design produces the desired magnitude response. The roots of the characteristic equation are checked to verify the proper location of the dominant pole pair. A comparison is made between the third order approximation and the fifth order one.
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Dow, Baker Camille. "The humanitarian distribution of the BioSand concrete filter." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ66977.pdf.
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Ahrens, Henning [Verfasser]. "The inverse problem of Magnetocardiography - Activation time imaging with the Extended Kalman Filter and the Unscented Kalman Filter / Henning Ahrens." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1119802849/34.
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Walter, Sandra L. "Optimizing the efficiency and filter area of the SurgiBox Environmental System by redistributing effective media area across filter length." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127866.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (page 46).
Across the globe, billions of people lack access to safe surgery. SurgiBox is working to lower that number by creating a portable surgical environment for patients in need. To do this, they are working to improve their air filtration system by better utilizing filter media to create a more efficient system. To help SurgiBox achieve this goal, Solidworks Flow Simulation Models were created and analysed to determine what parameters would be necessary to achieve a goal of a uniform velocity profile while meeting volumetric flow rate specifications. These models show that it is possible to achieve a uniform velocity distribution by using filters with varied resistances to air flow. It was found that, neglecting edge effects, the pressure drops (at a defined velocity) of the filter follow a linear trend across the length of the filter. However, these models also show that edge effects lead to significant air flow inconsistencies revealing that if these edge effects are not addressed, the system may quickly fall out of specification. Numerically generated "ideal" system centerline velocity and pressure curves were created to be used as comparative tools while conducting experiments on the SurgiBox system. These, in combination with the SolidWorks models will inform design changes to the SurgiBox system and help the SurgiBox team quantitativly assess the quality of their designs.
by Sandra L. Walter.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Šotner, Roman. "Vícefunkční přeladitelný aktivní filtr." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217657.
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The diploma thesis deals about design of the ARC multifunctional filters using modern functional blocks. These active blocks are for example voltage feedback operational amplifiers (OAs), operational transconductance amplifiers (OTAs), current conveyors (CCIIs) or current mode analog multipliers, current feedback amplifiers (CFAs), integrated circuits with switched capacitors building blocks (SCs) and digital potentiometers. The filters are studied with ideal circuit models and models of third level (3) based on voltage controlled voltage sources, voltage controlled current sources etc. (analog behavioral modelling). The professional macromodels are used for example LT 1364 (Linear Technology), EL 2045 (Intersil), LT 1228 (Linear Technology), LM 13700 (National Semiconductor), EL 2082 (Intersil), AD 844 (Analog Devices) and others. The circuits of the designed filters are simulated in PSpice (OrCAD), parasite effects and effects of the real parts are studied. Tuning and electronic adjusting parameters these filters are discussed and controlled by simulation in PSpice. Properties some simulated circuits are compare with experimental results. In conclusion individual filters are discussed and compared their properties. The constructional details of the some filters are presented at the end of this work.
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Wolanský, David. "Optimalizace koaxiálních filtrů metodou Tuning-Space Mapping v CST." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218609.
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This thesis deals with optimization of coaxial cavity filters. It thoroughly describes optimization method Tuning – Space Mapping (TSM) in CST Studio. It focuses on the explanation of the fine and the coarse model and their mutual link. The whole algorithm is illustrated and tested on the third-order coaxial cavity filter working in the band of 880 – 960MHz. In order to check the function of TSM, the algorithm is applied on fourth-order filter, triplet filter and quadruplet filter. Another part of the thesis focuses on the automatization of the whole optimization procedure. Macros for automatic determination of calibration constants and automatic calibration process between the coarse and the fine model are proposed and programmed in CST. The complete optimization procedure is applied on optimization of seventh-order filter with two cross couplings.
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Gundala, JayaKrishna. "A study on the decimation stage of a Δ-Σ ADC with noise-shaping loop between the stages." Thesis, Linköpings universitet, Elektroniksystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69319.
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The filter complexity in the multi-stage decimation system of a Δ-Σ ADC increases progressively as one moves to higher stages of decimation due to the fact that the input word length of the higher stages also increases progressively. The main motivation for this thesis comes from the idea of investigating a way, to reduce the input word length in the later filter stages of the decimation system which could reduce the filter complexity. To achieve this, we use a noise-shaping loop between the first and later stages so that the input word length for the later stages remains smaller than in the case where we do not use the noise-shaping loop. However, the performance (SNR/ Noise-level) level should remain the same in both cases. This thesis aims at analyzing the implications of using a noise-shaping loop in between the decimation stages of a Δ-Σ ADC and also finding the appropriate decimation filter types that could be used in such a decimation system. This thesis also tries to compare the complexity introduced by using the noise-shaping loop with the reduction achieved in the later decimation stages in terms of the input word length. Filter required in the system will also be optimized using minimax optimization technique.
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Mikhailov, Miroslav I. "Acid placement and coverage in the acid jetting process." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1592.
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Ali, Chachar Mumtaz, and Asif Iqbal Chaudhry. "Smart Filter-A Searching Approach in the e-Me Project." Thesis, Högskolan i Borås, Institutionen Handels- och IT-högskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-20819.
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In the past years, the information was kept on the physical medium and people struggle more to get the right information. Everyone tries to search the information in a smart way using different scenarios. With the passage of time as computer became the essential part of daily life and the search engines came into action. When we talk about the search engines, they are also the part of Information Technology (IT) revolution to find the material or information in a simple and easy way in less time span. These search engine help in finding the information instead of the physical media quickly. By the never ending efforts of the researchers, the information which was available only in physical medium or from other resources has been transferred to a single platform using IT artifacts. Now, the efficient accessibility of this information is an issue. There are a number of e-services available on the computer network around the globe from where the users can get the information according to their needs, but some time these e-services do not provide user demanded results because of the improper implementation of IT artifacts.Our research is focused on the e-Me project i.e. a comprehensive knowledge based Electronic Assistant platform given by Innovation Lab. This project has a number of good e-services to assist the user electronically in course schedules, record of books, planning transportation, course program progress and number of other tasks at one place. This project is also used to co-design approach to initiate the users as a stakeholder. The users create a profile according to the services of the e-Me project and the users can search these services according to their needs. Our research is to provide an efficient smart filter to search information about services according to users needs. We studied the IT Artifacts and adopt the new research methodology called ―Action Design Research‖. This research is specifically adopted by researchers for the IT based system. In our research we cover the core IT Artifacts i.e. human computer interaction, user centered design, interaction design principles. These artifacts are further verified by the documents in the form of interviews and observation. The results were achieved by taken interviews from three interviewers having expertise in IT fields and they are also aware about the users‘ perception. At the end of this research we came up with the design prototype of the smart filter.Program: Magisterutbildning i informatik
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Paredes, Stephanie D. "Adoption of the SAWYER Water Filter in Peru." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6127.
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In Peru, lack of water, sanitation, and hygiene (WASH) results in 6,600 deaths per year that represents approximately 3.9% of total deaths. Three thousand and nine hundred of these deaths were due to diarrheal diseases (Prüss-Üstün et al., 2008). Systematic reviews suggest that interventions to improve microbial quality of drinking water are successful in reducing diarrheal diseases (Fewtrell et al., 2005; Clasen et al., 2007; Fry et al., 2013). Interventions for household water treatment and safe storage to ensure safe drinking water reduce diarrhea by 31-52% (WHO/UNICEF, 2013).
The SAWYER PointONE filter, a portable and adaptable membrane filtration device as small as the hand, is one point-of-use (POU) technology option for populations that rely on unsafe water from an improved source, or for areas that still rely on unimproved water sources for drinking and cooking. The filter functions strictly through mechanical exclusion accomplished by a hollow fiber membrane. The filters are certified for 0.1 μm as the largest pore size; therefore preventing diarrhea-causing bacteria such as E. coli, cholera, and typhoid to pass through the membrane.
This research focuses on SAWYER water filter users who use a filter purchased through a sales agent in Independencia, Ica, Peru. Fifteen households in 9 communities and a total of 39 individuals were surveyed with the overall goal of better understanding the adoption of the SAWYER water filter as a POU water treatment technology in relation to three themes of: 1) household socio-economic factors 2) water, sanitation and hygiene (WASH) related characteristic and behaviors of users, and 3) Health Belief Model factors.
The results showed SAWYER water filter users to have higher socio-economic status on average. All households had a high Progress out of Poverty Index® (PPI®) score. The heads of households, both male and female, were found to be more educated than the national average. Female heads of house were more educated than the male heads of house. There was a significant difference in the education levels of the female heads of house as compared to the national levels (p =0.006), with the female heads of house in the study having superior university degrees at three times the national percentage. The heads of house were also married at a higher percentage than the national average.
SAWYER water filter users also have greater access to media than the regional average. All homes were equipped with at least one TV with cable. Results showed a significant difference in households having a computer within the home as compared to the regional percentage (p < 0 .001) and also in having Internet in the home as compared to the regional percentage (p < 0.001).
Most houses (13/15) have running water all the time and all have a sink, shower, and toilet. Indoor connection and sewage type were not found to be statistically different from national average. Most people (67%) reported to always use soap and several participants mentioned liquid handwashing soap. Users reported handwashing after going to the bathroom (64.1%) more than before eating (38.5%) or cooking (46%).
The Health Belief Model survey revealed that SAWYER water filter users perceive diarrhea as more severe for children, even though they do consider themselves susceptible. Clear benefits of adopting the filter include saving money, improving water quality, and saving time, but the barriers to filter adoption were unclear. Most users had contact with another person who demonstrated or recommended the filter prior to adopting the filter, highlighting the importance of interpersonal contact for promoting filter use. Turbidity during rainy season was also found to be an important cue to action.
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Yuk, Ka Man. "Color demosaicking for the Bayer color filter array /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20YUK.
Full text
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Fang, Po-sheng, and 方柏勝. "Polarization Independent THz Photonics : Phase Shifter and Tunable Bandpass Filter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/rv674c.
Full textAbstract:
碩士國立中山大學
光電工程學系研究所
102
In recent years, terahertz (THz) photonics have attracted plenty of attraction due to its remarkable progress. As its potential in the field of communication, spectrum analysis and so on, the demand of high performance quasi-optic components such as phase shifters, band pass filters or polarizers is strongly increasing. However, these devices need polarizer or other polarization control system to achieve polarization independency. The first part of this thesis, polarization independent electrical controlled 2p THz phase shifter with sub-second modulation speed was demonstrated by using cholesteric liquid crystal (CLC). The device was constructed by stacking three CLC layers. Each CLC layer with thickness of 1.5mm was sandwiched by two fused silica glasses coated with ITO for electrode. The CLC was made by chiral dopant mixed in a nematic liquid crystal (NLC) host BL006 and pitch length is around 20μm. The structure of CLCs became visible homeotropic texture from invisible focal conic texture when the driving voltage increases from zero till over 360V. The modulation speed increases as the driving voltage increasing. The response time up to 500 ms was successfully achieved using the multi-layer structure. The polarization independence of this component was performed about l/60. Feasibility of 100ms modulation speed was discussed as well. Second, we demonstrated a polarization independent tunable THz band pass filter based on one-dimensional photonic crystal cavity and using CLC. The CLC layer, made by chiral dopant mixed in a nematic liquid crystal (NLC) host BL006 with around 20μm pitch length, was sandwiched by two Bragg mirror with half-wavelength optical thickness of 650μm. The THz Fabry-Perot(FP) is demonstrated using two three-pairs THz high reflective structures. The stop band of 85GHz and 3dB bandwidth of 11GHz are demonstrated. The corresponding Q-factor is about 38. By filling with CLC in the THz FP, the frequency can be tuned from 406GHz to 420GHz as applying voltage on CLC cell. This is the first time to our best knowledge that the electrical controlled THz narrow-band-pass is polarization independent and with tuning rang of 14GHz.
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Houshmand, Kaveh. "Defect Detection Via THz Imaging: Potentials & Limitations." Thesis, 2008. http://hdl.handle.net/10012/3782.
Full textAbstract:
Until recent years, terahertz (THz) waves were an undiscovered, or most importantly, an unexploited area of electromagnetic spectrum. This was due to difficulties in generation and detection of THz waves. Recent advances in hardware technology have started to open up the field to new applications such as THz imaging. This non-destructive and non-contact imaging technique can penetrate through diverse materials such that internal structures, in some cases invisible to other imaging modalities, can be visualized.
Today, there are variety of techniques available to generate and detect THz waves in both pulsed and continuous fashion in two different geometries; transition, and reflection modes. In this thesis continuous wave THz imaging was employed for higher spatial resolution.
However, with any new technology comes its challenges; automated processing of THz images can be quite cumbersome. Low contrast and the presence of a widely unknown type of noise make the analysis of these images difficult. In this work, there is an attempt to detect defects in composite material via segmentation by using a Terahertz imaging system. According to our knowledge, this is the first time that this type of materials are being tested under Terahertz cameras to detect manufacturing defects in aerospace industry.
In addition, segmentation accuracy of THz images have been investigated by using a phantom. Beyond the defect detection for composite materials, this can establish some general knowledge about Terahertz imaging, its capabilities and limitations.
To be able to segment the THz images successfully, pre-processing techniques are inevitable. In this thesis, a variety of different image processing techniques, self-developed or available from literature, have been employed for image enhancement. These methods range from filtering to contrast adjustment to fusion of phase and amplitude images by using fuzzy set theory, to just name a few. The result of pre-procssing and segmentation methods demonstrates promising outcome for future work in this field.
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饒振茂. "The stepped-impedance resonators composed bandpass filters and the sample filter designs." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/77824631945750996928.
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Lin, Chih-Hsin, and 林志新. "The Design of 3-D Perfect Reconstruction Filter Banks, Digital All-Pass Filters, and Complex FIR Digital Filters." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/22345458364143107720.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
87
This thesis presents several novel and efficient techniques for designing three-dimensional (3-D) perfect reconstruction (PR) filter banks, FIR digital all-pass filters, and complex FIR digital filters in minimax sense. The proposed approaches are developed based on the affine and dual affine scaling variants of Karmarkar's algorithm. As for the 3-D perfect reconstruction digital filter banks, two novel techniques are proposed for designing PR filter banks with FIR analysis and synthesis filters having linear phase responses. The designed analysis and synthesis filters are in the minimax sense subject to the perfect reconstruction constraints. With regard to the design of FIR digital all-pass filters, we propose design techniques via minimizing the peak magnitude error and peak phase error simultaneously or minimizing the peak magnitude error and peak group delay error simultaneously. The filter coefficients are obtained by an affine scaling variant of Karmarkar's algorithm. For designing complex FIR digital filters, the original complex approximation is divided into two real ones first. Then the affine scaling variant of Karmarkar's algorithm is also applied to minimize the real part and imaginary part error in minimax sense to get the complex impulse response coefficients. From the simulation examples demonstrated in each chapter of this thesis, the effectiveness of the proposed design techniques for each considered problem can be confirmed.
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鍾隆魁. "Effects of Reynolds Numbers and Filter Structure on the Performance of Fibrous Filters." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/66816306633005845596.
Full textAbstract:
碩士中原大學
機械工程學系
85
The purpose of the proposed research is to study the filter performance comprising of pressure drop and particle collection efficiency. Some parameters that effect the filter performance in particle deposition mechanism, the major discussion is the diffusion deposition mechanism due to Brownian motion. Following parameters in filter structure, two models comprising of aligned array and staggered array, packing density. Another discussion about the effect due to Reynolds number is also included. Air flow is modeled as an incompressible, steady-state and two-dimensional laminar flow. The equation of particle concentration is founded by using Eulerian model. Boundary conditions inside filter are considered as fully developed velocity at inlet and outiet. Fully Navier-Stokes equations of flow field and concentration equation are solved using finite volume approach to obtain flow velocities, pressure drop and concentration, and calculating the particle collection efficiency finally. The model is incorporated into the PHOENICS CFD software package in order to make the reguired calculations comprising flow field and particle concentration, then analysis the performance of filter.
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Rencken, Gunter Eduard. "Performance studies of the tubular filter press." Thesis, 1992. http://hdl.handle.net/10413/8670.
Full textAbstract:
The tubular filter press is a novel tubular configured filter press for the filtration or dewatering
of sludges.
The unique features of the filter press are:
(i) during the cake deposition cycle, cake is deposited on the internal walls of a
self-supporting array of horizontal collapsible porous fabric tubes;
(ii) during the cake removal cycle, cake is dislodged from the tube walls by means of a
roller cleaning device and the dislodged flakes of cake are hydraulically transported
out of the tubes by the feed sludge which is simultaneously re-circulated at a high
flow rate through the tubes. The two main problems experienced on a prototype tubular filter press, which was erected at a water treatment plant to dewater the sludge from the clarifier underflow, were: (i) tube blockage problems during the filtration cycle; (ii) low cake recoveries (high cake losses) during the cake removal cycle. The following objectives which were defined for this study, were regarded as fundamental prerequisites for any solution of the two main problems: (i) to develop a predictive dead-end internal cylindrical model for compressible cake filtration inside a porous tube; (ii) to investigate the cake losses during the cake removal cycle of the tubular filter press; (iii) to develop a predictive unsteady-state internal cylindrical cross-flow microfiltration model for a non-Newtonian sludge which, when filtered, produces a very compressible cake. (An alternative to dead-end filtration during the filtration cycle of a tubular filter press is low axial velocity cross-flow filtration). On the basis of the objectives the study was divided into three separate investigations. To date no one has developed a model which incorporates the cylindrical configuration of the filter medium for dead-end compressible cake filtration inside a porous tube. The most comprehensive model for dead-end external cylindrical compressible cake filtration is that of Tiller and Yeh (1985). This model was adapted for internal cylindrical compressible cake filtration. In essence the model by Tiller and Yeh (1985) requires the solution of a system of two ordinary
differential equations in order to calculate the radial variation of solids compressive and liquid
pressures in a compressible filter cake deposited externally on a cylindrical surface. The
relevant equations were derived for internal cylindrical compressible cake filtration and it was
found that one of the differential equations changes from: dPl/dr = H1/2nrK (external cylindrical) to dPl/dr = H12nrK (internal cylindrical).
The other differential equation remains unaltered for internal cylindrical compressible cake
filtration. A batch of waterworks clarifier sludge from the prototype tubular filter press was used for experiments to evaluate the performance of the internal cylindrical filtration model. The cake produced by the filtration of this sludge had to be characterized for the model.
Compression-permeability data were obtained over a wide solids compressive pressure range.
A Compression-Permeability (C-P) cell was used for high solids compressive pressures
(10 kPa<_ ps<_400 kPa) and settling tests were used for low solids compressive pressures
(0,0065 Pa <_ ps < 525,6 Pa). The cake was found to be very compressible (compressibility
coefficient = 0,989). Empirical equations of the form, K' = Fps - b and (1 - E) = B pbs , were
derived from the C-P cell and settling tests to relate permeability and porosity to solids
compressive pressure. The equations were slightly different to those proposed by Tiller and
Cooper (1962). The predictions by the internal cylindrical compressible cake filtration model were compared to the results of constant pressure internal cylindrical filtration experiments, at filtration pressures of 100 kPa, 200 kPa and 300 kPa, using the waterworks clarifier sludge. The internal diameter of the filter tube which was used for the experiments was 26,25 mm. The model accurately described the results of the filtration experiments in terms of volume of filtrate, average cake dry solids concentration, filtrate flux and internal cake diameter. The differences between external cylindrical, internal cylindrical and planar compressible cake filtration were highlighted. Since the tubular filter press is a novel process, the cake losses during the cake removal cycle have not been investigated before. An investigation was therefore conducted into the cake losses which occur during the cake removal cycle. The same batch of clarifier sludge was also used for the investigation of cake losses during the cake removal cycle at filtration pressures of 100 kPa and 300 kPa. It was found that significant cake losses occurred due to: (i) the shear of the cleaning fluid prior to the action of the rollers (losses varied between 10 % to 20 % of the deposited cake dry solids); (ii) the combined action of the rollers when dislodging the cake and the hydraulic conveyance of the dislodged flakes of cake (losses varied between 30 % to 40 % of deposited cake dry solids). A new shear model, which was developed, accurately predicted the cake losses and increase in internal cake diameter and average cake dry solids concentration, which occurred due to the shear of the cleaning fluid. For the shear model the sludge (cake) rheology was determined using a capillary-tube viscometer. It was found that the sludges exhibited Bingham plastic behaviour in the solids concentration range: 3,58 % m/m <_Cs <_16,71 % m/m. The cake losses due to the action of the rollers and hydraulic conveyance of the dislodged flakesof cake decreased markedly as filtration pressure and filtration time were increased, while a decrease in path length for hydraulic conveyance of dislodged cake flakes resulted in a mild decrease in these cake losses. A literature review revealed that to date only one mathematical model (Pearson and Sherwood, 1988) is available for the unsteady-state cross-flow microfiltration of a non-Newtonian sludge which, when filtered, produces a compressible cake. A new unsteady-state internal cylindrical
axial convection shear model (for laminar flow of the feed sludge) was developed for cross-flow microfiltration of a Bingham plastic sludge which, when filtered, produces a very compressible cake. Similar to the approach by Pearson and Sherwood (1988) this model is a combination of the dead-end internal cylindrical compressible cake filtration model and the "cleaning fluid" shear model. The major difference between the new model and the model by Pearson and Sherwood (1988) is that unlike the convection-diffusion model of Pearson and Sherwood (1988), diffusive and shear induced diffusive back-mixing of particles were assumed to be negligible. The existence of a shear plane within the cake forms the basis of the model. Those cake layers with a yield stress less than the shear stress exerted by the flowing feed sludge at the inner cake wall are convected along the shear plane. It was assumed that the axial convection of the solids in the moving cake layer along the shear plane is the sole mechanism for removal of solids deposited at the cake surface. The model was compared to the results of cross-flow microfiltration experiments at one filtration pressure (300 kPa) and cross-flow flow rates of 0,84 l / min; 1,58 l / min; 2,43 l / min and 4,44 l /min. The model accurately described the variation of filtrate flux, internal cake diameter and average cake dry solids concentration during the unsteady-state time period. The model, however, had to be "extended" by incorporating empirical equations for changes in permeability and porosity (due to further cake compaction) to obtain a good fit between the model and experimental results during the pseudo steady-state time period. The results of all three investigations provide a greater understanding of the cake deposition process (during both dead-end and cross-flow filtration modes) and the cake removal process for the tubular filter press. This should assist in finding solutions to the two main problems which were experienced on the prototype tubular filter press.Thesis (Ph.D.)-University of Natal, Durban, 1992.
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Shiau, Bo-Luen, and 蕭博倫. "The Design of digital filters and filter banks with L-1 and L-infinite norm." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/33875890784270862634.
Full textAbstract:
碩士國立臺灣大學
電機工程研究所
84
In this thesis, we consider the design and application problem of filters and filter banks.We first introduce the basic concept of optimization and the interior-point search algorithm- first presented by KarmarKar , then we apply this algorithm to the design problem of some special 1-D filters, 2-D filters for sampling structure conversion ,QMF banks , and 2-D QQMF with L-1 and L-infinite norm. In the above design topics,we use some different optimization criteria for the design of each topic. The computer simulations show the effectiveness of the proposed method are included.
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Pan, Hong-Shiuann, and 潘宏炫. "A Filter Bank Multicarrier System Based on the Discrete Hartley Transform and Two Prototype Filters." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8t5yqv.
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Purfürst, Marcus. "Influence of Soot on the Transport Mechanisms inside the Filter Wall of SCR-Coated Diesel Particulate Filters." 2017. https://ul.qucosa.de/id/qucosa%3A21159.
Full textAbstract:
The effect of soot on the catalytic properties of a diesel particulate filter coated with a catalyst for the selective catalytic reduction of NOx with ammonia (SDPF) was studied by means of model-gas experiments. After loading of the SDPF with model soot from 0 to 10 g l-1, the NH3 storage as well as the catalytic DeNOx behavior of the standard SCR reaction was investigated. The model soot present in the filter was shown to have an NH3 storage capacity. The soot deposit inside the SDPF filter wall lead to a decreased NO conversion in SCR experiments of up to 20 %. The NH3 breakthrough was found to be shifted towards earlier time-on-stream during NH3 adsorption on soot loaded SDPF samples. Both effects could be attributed to a diffusive mass transport limitation of the gas species through the soot to reach at the chemically active sites inside SDPF filter wall. The self-diffusion coefficient of NH3 probe molecules within a soot layer could be measured using Pulsed Field Gradient-NMR technique. The unit collector model is capable of describing the backpressure upon soot loading with a depth filtered (inside filter wall) soot amount of 1 g l-1 and 0.36 g l-1, respectively, for both SDPF types under investigation. Based on Scanning Electron Microscopy (SEM) investigation a 1-D microscopic soot filter wall-model was set up. The model implies soot as diffusion barrier for mass transport. It was calibrated based on experimental observations and allows to conclude on the distribution of the soot within the filter wall. Thus, a high soot-coverage of the porous filter wall close to the inlet channel, a slightly covered middle part and a soot free zone close to the outlet explains the observed reduction in NO conversion as well as the NH3 breakthrough at earlier time-on-stream during NH3 adsorption experiments for SDPF samples loaded with soot. A modelled homogeneous soot distribution (0.6 µm soot layer on top of washcoat) within the whole SDPF was shown to result in NO conversion drop up to 45 %.
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Gao, Qiao-Xin, and 高巧欣. "Study on the high-voltage stainless steel mesh filter for the improvement of commercial oil mist filters." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/jmc7m3.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
107
According to the global report of the World Health Organization in 2014, the global population affected by indoor pollution is mainly in Asia and Africa, and it influences about 3 billion people. Due to the lack of ventilation and filtration systems, oil mist generated by cooking kills about 3.5 to 4.3 million people every year. According to TEDS(Taiwan Emission Data System) 9.0, Taiwan''s emissions from restaurants and households account for 6.39% and 17.13% of the total PM2.5 (PM: Particulate matter) emissions. Therefore, how to effectively prevent the inhalation of oil mist become one of the main tasks in the world. In this study, methods to enhance commercial oil-mist filters are proposed and studied. Since the commercial polypropylene (PP) electrostatic filter provides filtration mechanism of electrostatic attraction, it has a higher filtration efficiency for the particle size between 100 to 400 nm. However, captured oil mist can mask PP fibers, and the chargeability and its filtration efficiency can be depleted very quickly. Therefore, a method to modify the surface of PP fibers is developed in this thesis. Nanoparticles are sprayed on the surface of PP fibers to change its surface energy. It was found that spraying PTFE (polytetrafluoroethene) nanoparticles on PP fibers can improve the filtration efficiency and achieve 23.25 % higher performance. Secondly, electric field was introduced to commercial filter by using stainless steel meshes to sandwich these filters. Commercial filters are placed between two stainless steel meshes. It was found that letting the front stainless steel mesh to be positively charged and grounded the other one on the back, the quality factor is 6.46 times higher than no charged stainless steel meshes. It also was found that placing commercial filters sequentially as oleophilic filter at front followed by putting a oleophobic filter behind it can have a better filtration efficiency by 2.47 %. Finally, by placing a high porous TPU (thermoplastic polyurethane) filter in front of all commercial filters, the overall pressure drop can be significantly decreased by 27.36 % and the filtration efficiency can increased by 2.72 %. This design can prolong the usage of commercial filters for oil mist filtrations and also decrease the system pressure drop.