Dissertations / Theses on the topic 'Heterogeneous solution'

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2006.
Thesis Advisor(s): Alexander Bordetsky. "March 2006." Includes bibliographical references (p. 61-65). Also available online.

The scope of this thesis is to analyze the feasibility of having different wireless mesh network architectures transfer data to a wired network via a joint (universal) access point (UAP). Additionally this thesis analyzes the feasibility of using similar joint (universal) access point technology to allow heterogeneous wireless mesh network devices in close proximally to the UAP transmit data to/from each other via the UAP. This research also includes evaluating COTS tools for possible implementation of a joint access point as well as seeking partnership with private industry to assist in research efforts and/or the development or joint (universal) access point solution(s). The thesis concludes with a recommendation on application of universal joint point technology, to include recommendations for implementation of such technology in the Tactical Network Topology (TNT) environment.

This report considers the effect of measuring randomly varying local hydraulic conductivities K(x) on one's ability to predict deterministically, without upscaling, steady state flow in bounded domains driven by random source and boundary terms. Our aim is to allow optimum unbiased prediction of hydraulic heads h(x) and Darcy fluxes q(x) by means of their ensemble moments, , and c, conditioned on measurements of K(x). It has been shown earlier that these predictors satisfy a deterministic flow equation which contains an integro-differential "residual flux" term. This term renders c nonlocal and non-Darcian so that the concept of effective hydraulic conductivity looses meaning in all but a few special cases. Instead, the residual flux contains kernels which constitute nonlocal parameters that are conditional on hydraulic conductivity data and therefore nonunique. The kernels include symmetric and nonsymmetric second -rank tensors as well as vectors. We derive exact integro-differential equations for second conditional moments of head and flux which constitute measures of predictive uncertainty. We then develop recursive closure approximations for the moment equations through expansion in powers of a small parameter ay which represents the standard estimation error of In K(x). Finally, we solve these nonlocal equations to first order in a by finite elements on a rectangular grid in two dimensions. We also solve the original stochastic flow equations by conditional Monte Carlo simulation using finite elements on the same grid. Upon comparing our nonlocal finite element and conditional Monte Carlo results we find that the former are highly accurate, under either mean uniform or convergent flows, for both mildly and strongly heterogeneous media with a as large as 4 - 5 and spatial correlation scales as large as the length of the domain. Since conditional mean quantities are smooth relative to their random counterparts our method allows, in principle, resolving them on relatively coarse grids without upscaling. We also examine the quc on under what conditions can the residual flux be localized so as to render it approximately Darcian. One way to achieve such localization is to treat ' "draulic conductivity as if it was locally homogeneous and mean flow as if it was locally uniform. This renders the flux predictor Darcian according to c _ - Kc(x) \7c where Kc(x) is a conditional hydraulic conductivity tensor which depends on measurements of K(x) and is therefore a nonunique function of space. This function can be estimated by means of either stochastically- derived analytical formulae or standard inverse methods (in which case localization coincides with common groundwater modeling practice). We use the first approach and solve the corresponding localized conditional mean equation by finite elements on the same grid as before. Here the conditional hydraulic conductivity is given by the geometric mean KG(x). Upon comparing our localized finite element solution with a nonlocal finite element solution and conditional Monte Carlo results, we find that the first is generally less accurate than the second. The accuracy of the localized solution deteriorates rel tive to that of the nonlocal solution as one approaches points of conditioning and singularity, or as the variance and correla': ^n scale of the log hydraulic conductivity increase. Contrary to the nonlocal solution, locàlzation does not yield information about predictive uncertainty.

This work focuses on understanding the heterogeneous/homogeneous nature of the catalytic species for a variety of immobilized metal precatalysts used for C-C coupling reactions. These precatalysts include: (i) tethered organometallic palladium pincer complexes, (ii) an encapsulated small molecule palladium complex in a polymer matrix, (iii) mercapto-modified mesoporous silica metalated with palladium acetate, and (iv) amino-functionalized mesoporous silicas metalated with Ni(II). As part of this investigation, the use of metal scavengers as selective poisons of homogeneous catalysis is introduced and investigated as a test for distinguishing heterogeneous from homogeneous catalysis. The premise of this test is that insoluble materials functionalized with metal binding sites can be used to selectively remove soluble metal, but will not interfere with catalysis from immobilized metal. In this way the test can definitely distinguish between surface and solution catalysis of immobilized metal precatalysts. This work investigates three different C-C coupling reactions catalyzed by the immobilized metal precatalysts mentioned above. These reactions include the Heck, Suzuki, and Kumada reactions. In all cases it is found that catalysis is solely from leached metal. Three different metal scavenging materials are presented as selective poisons that can be used to determine solution vs. surface catalysis. These selective poisons include poly(vinylpyridine), QuadrapureTM TU, and thiol-functionalized mesoporous silica. The results are contrasted against the current understanding of this field of research and subtleties of tests for distinguishing homogeneous from heterogeneous catalysis are presented and discussed.

Des motifs nanométriques d’oxydes métalliques (TiO2, Al2O3, ZrO2) étaient synthétisés avec une technique bottom-up. Un mélange de précurseurs moléculaires et de micelles préformées des copolymères à block est déposé sur des substrats tels que la silice, l’or ou l’ITO par voie de trempage. Des monocouches de micelles entourées par les espèces inorganiques sont deposées à des concentrations et des vitesses de dépôt faibles. Calcination élimine les copolymères et des motifs (perforations rondes, canaux, anneaux,…) rigides d’oxyde métallique sont obtenus. La présence de monocouches de perforations d’un diamètre entre 10 et 70nm ainsi que l’accessibilité de la surface du substrat a travers ces perforations a été confirme avec plusieurs méthodes de caractérisation. Les dessins du type nanocrateres sont bifunctionels, peuvent être functionalisé sélectivement et ont une bonne stabilité mécanique, thermique et chimique ce qui fait que ces matériaux sont intéressants pour plusieurs applications
Metal oxide nanopatterns (TiO2, Al2O3, ZrO2) were synthesised with a bottom up technique that combines the method of chemical solution deposition and the self-organisation properties of block copolymer micelles on a substrate surface through Evaporation Induced Micelle Packing (EIMP). Molecular precursors were mixed with micelles in EtOH/THF/H2O or EtOH/THF and the solutions were dip coated onto various substrates such as silicon wafers, gold or ITO. High dilution and low withdrawal speed lead to the deposition of micelle monolayers surrounded by inorganic precursors. A calcination step eliminates the block copolymer and rigid metal oxide nanopatterns with various motifs like circular perforations (nanocraters), channels or rings are obtained. The size and kind of the motifs can be controlled by adjusting several crucial parameters during solution preparation like the kind and size of the used block copolymer in combination with the used solvent composition, concentration and conditioning. High kinetics of evaporation during the dip coating further allow ordering of nanocrater perforations in hexagonal patterns. The synthesised patterns were characterised by ellipsometry, AFM, FEG-SEM, GISAXS, XPS, cyclic voltametry and contact angle measurements. The presence of monolayers of perforations with diameters of 10-70nm and accessibility of the substrate surface through the perforations was confirmed. Nanocrater patterns show inherent bifunctionality and the substrate surface and the pattern can be selectively functionalised. In addition, nanocrater patterns are mechanically, chemically and thermally stable and are therefore interesting materials for various kinds of applications

Aquesta tesi per compendi centra les seves contribucions en l'aprenentatge i innovació de les Xarxes de Nova Generació. És per això que es proposen diferents contribucions en diferents àmbits (Smart Cities, Smart Grids, Smart Campus, Smart Learning, Mitjana, eHealth, Indústria 4.0 entre d'altres) mitjançant l'aplicació i combinació de diferents disciplines (Internet of Things, Building Information Modeling, Cloud Storage, Ciberseguretat, Big Data, Internet de el Futur, Transformació Digital). Concretament, es detalla el monitoratge sostenible del confort a l'Smart Campus, la que potser es la meva aportació més representativa dins de la conceptualització de Xarxes de Nova Generació. Dins d'aquest innovador concepte de monitorització s'integren diferents disciplines, per poder oferir informació sobre el nivell de confort de les persones. Aquesta investigació demostra el llarg recorregut que hi ha en la transformació digital dels sectors tradicionals i les NGNs. Durant aquest llarg aprenentatge sobre les NGN a través de les diferents investigacions, es va poder observar una problemàtica que afectava de manera transversal als diferents camps d'aplicació de les NGNs i que aquesta podia tenir una afectació en aquests sectors. Aquesta problemàtica consisteix en el baix rendiment durant l'intercanvi de grans volums de dades sobre xarxes amb gran capacitat d'ample de banda i remotament separades geogràficament, conegudes com a xarxes elefant. Concretament, això afecta al cas d'ús d'intercanvi massiu de dades entre regions Cloud (Cloud Data Sharing use case). És per això que es va estudiar aquest cas d'ús i les diferents alternatives a nivell de protocols de transport,. S'estudien les diferents problemàtiques que pateixen els protocols i s'observa per què aquests no són capaços d'arribar a rendiments òptims. Deguda a aquesta situació, s'hipotetiza que la introducció de mecanismes que analitzen les mètriques de la xarxa i que exploten eficientment la capacitat de la mateixa milloren el rendiment dels protocols de transport sobre xarxes elefant heterogènies durant l'enviament massiu de dades. Primerament, es dissenya l’Adaptative and Aggressive Transport Protocol (AATP), un protocol de transport adaptatiu i eficient amb l'objectiu de millorar el rendiment sobre aquest tipus de xarxes elefant. El protocol AATP s'implementa i es prova en un simulador de xarxes i un testbed sota diferents situacions i condicions per la seva validació. Implementat i provat amb èxit el protocol AATP, es decideix millorar el propi protocol, Enhanced-AATP, sobre xarxes elefant heterogènies. Per això, es dissenya un mecanisme basat en el Jitter Ràtio que permet fer aquesta diferenciació. A més, per tal de millorar el comportament del protocol, s’adapta el seu sistema de fairness per al repartiment just dels recursos amb altres fluxos Enhanced-AATP. Aquesta evolució s'implementa en el simulador de xarxes i es realitzen una sèrie de proves. A l'acabar aquesta tesi, es conclou que les Xarxes de Nova Generació tenen molt recorregut i moltes coses a millorar causa de la transformació digital de la societat i de l'aparició de nova tecnologia disruptiva. A més, es confirma que la introducció de mecanismes específics en la concepció i operació dels protocols de transport millora el rendiment d'aquests sobre xarxes elefant heterogènies.
Esta tesis por compendio centra sus contribuciones en el aprendizaje e innovación de las Redes de Nueva Generación. Es por ello que se proponen distintas contribuciones en diferentes ámbitos (Smart Cities, Smart Grids, Smart Campus, Smart Learning, Media, eHealth, Industria 4.0 entre otros) mediante la aplicación y combinación de diferentes disciplinas (Internet of Things, Building Information Modeling, Cloud Storage, Ciberseguridad, Big Data, Internet del Futuro, Transformación Digital). Concretamente, se detalla la monitorización sostenible del confort en el Smart Campus, la que se podría considerar mi aportación más representativa dentro de la conceptualización de Redes de Nueva Generación. Dentro de este innovador concepto de monitorización se integran diferentes disciplinas, para poder ofrecer información sobre el nivel de confort de las personas. Esta investigación demuestra el recorrido que existe en la transformación digital de los sectores tradicionales y las NGNs. Durante este largo aprendizaje sobre las NGN a través de las diferentes investigaciones, se pudo observar una problemática que afectaba de manera transversal a los diferentes campos de aplicación de las NGNs y que ésta podía tener una afectación en estos sectores. Esta problemática consiste en el bajo rendimiento durante el intercambio de grandes volúmenes de datos sobre redes con gran capacidad de ancho de banda y remotamente separadas geográficamente, conocidas como redes elefante, o Long Fat Networks (LFNs). Concretamente, esto afecta al caso de uso de intercambio de datos entre regiones Cloud (Cloud Data Data use case). Es por ello que se estudió este caso de uso y las diferentes alternativas a nivel de protocolos de transporte. Se estudian las diferentes problemáticas que sufren los protocolos y se observa por qué no son capaces de alcanzar rendimientos óptimos. Debida a esta situación, se hipotetiza que la introducción de mecanismos que analizan las métricas de la red y que explotan eficientemente la capacidad de la misma mejoran el rendimiento de los protocolos de transporte sobre redes elefante heterogéneas durante el envío masivo de datos. Primeramente, se diseña el Adaptative and Aggressive Transport Protocol (AATP), un protocolo de transporte adaptativo y eficiente con el objetivo maximizar el rendimiento sobre este tipo de redes elefante. El protocolo AATP se implementa y se prueba en un simulador de redes y un testbed bajo diferentes situaciones y condiciones para su validación. Implementado y probado con éxito el protocolo AATP, se decide mejorar el propio protocolo, Enhanced-AATP, sobre redes elefante heterogéneas. Además, con tal de mejorar el comportamiento del protocolo, se mejora su sistema de fairness para el reparto justo de los recursos con otros flujos Enhanced-AATP. Esta evolución se implementa en el simulador de redes y se realizan una serie de pruebas. Al finalizar esta tesis, se concluye que las Redes de Nueva Generación tienen mucho recorrido y muchas cosas a mejorar debido a la transformación digital de la sociedad y a la aparición de nueva tecnología disruptiva. Se confirma que la introducción de mecanismos específicos en la concepción y operación de los protocolos de transporte mejora el rendimiento de estos sobre redes elefante heterogéneas.
This compendium thesis focuses its contributions on the learning and innovation of the New Generation Networks. That is why different contributions are proposed in different areas (Smart Cities, Smart Grids, Smart Campus, Smart Learning, Media, eHealth, Industry 4.0, among others) through the application and combination of different disciplines (Internet of Things, Building Information Modeling, Cloud Storage, Cybersecurity, Big Data, Future Internet, Digital Transformation). Specifically, the sustainable comfort monitoring in the Smart Campus is detailed, which can be considered my most representative contribution within the conceptualization of New Generation Networks. Within this innovative monitoring concept, different disciplines are integrated in order to offer information on people's comfort levels. . This research demonstrates the long journey that exists in the digital transformation of traditional sectors and New Generation Networks. During this long learning about the NGNs through the different investigations, it was possible to observe a problematic that affected the different application fields of the NGNs in a transversal way and that, depending on the service and its requirements, it could have a critical impact on any of these sectors. This issue consists of a low performance operation during the exchange of large volumes of data on networks with high bandwidth capacity and remotely geographically separated, also known as Elephant networks, or Long Fat Networks (LFNs). Specifically, this critically affects the Cloud Data Sharing use case. That is why this use case and the different alternatives at the transport protocol level were studied. For this reason, the performance and operation problems suffered by layer 4 protocols are studied and it is observed why these traditional protocols are not capable of achieving optimal performance. Due to this situation, it is hypothesized that the introduction of mechanisms that analyze network metrics and efficiently exploit network’s capacity meliorates the performance of Transport Layer protocols over Heterogeneous Long Fat Networks during bulk data transfers. First, the Adaptive and Aggressive Transport Protocol (AATP) is designed. An adaptive and efficient transport protocol with the aim of maximizing its performance over this type of elephant network.. The AATP protocol is implemented and tested in a network simulator and a testbed under different situations and conditions for its validation. Once the AATP protocol was designed, implemented and tested successfully, it was decided to improve the protocol itself, Enhanced-AATP, to improve its performance over heterogeneous elephant networks. In addition, in order to upgrade the behavior of the protocol, its fairness system is improved for the fair distribution of resources among other Enhanced-AATP flows. Finally, this evolution is implemented in the network simulator and a set of tests are carried out. At the end of this thesis, it is concluded that the New Generation Networks have a long way to go and many things to improve due to the digital transformation of society and the appearance of brand-new disruptive technology. Furthermore, it is confirmed that the introduction of specific mechanisms in the conception and operation of transport protocols improves their performance on Heterogeneous Long Fat Networks.

Le sujet de cette thèse est le développement de méthodes itératives permettant la résolution degrands systèmes linéaires creux d'équations présentant plusieurs seconds membres simultanément. Ces méthodes seront en particulier utilisées dans le cadre d'une application géophysique : la migration sismique visant à simuler la propagation d'ondes sous la surface de la terre. Le problème prend la forme d'une équation d'Helmholtz dans le domaine fréquentiel en trois dimensions, discrétisée par des différences finies et donnant lieu à un système linéaire creux, complexe, non-symétrique, non-hermitien. De plus, lorsque de grands nombres d'onde sont considérés, cette matrice possède une taille élevée et est indéfinie. Du fait de ces propriétés, nous nous proposons d'étudier des méthodes de Krylov préconditionnées par des techniques hiérarchiques deux niveaux. Un tel pre-conditionnement s'est montré particulièrement efficace en deux dimensions et le but de cette thèse est de relever le défi de l'adapter au cas tridimensionel. Pour ce faire, des méthodes de Krylov sont utilisées à la fois comme lisseur et comme méthode de résolution du problème grossier. Ces derniers choix induisent l'emploi de méthodes de Krylov dites flexibles
The topic of this PhD thesis is the development of iterative methods for the solution of large sparse linear systems of equations with possibly multiple right-hand sides given at once. These methods will be used for a specific application in geophysics - seismic migration - related to the simulation of wave propagation in the subsurface of the Earth. Here the three-dimensional Helmholtz equation written in the frequency domain is considered. The finite difference discretization of the Helmholtz equation with the Perfect Matched Layer formulation produces, when high frequencies are considered, a complex linear system which is large, non-symmetric, non-Hermitian, indefinite and sparse. Thus we propose to study preconditioned flexible Krylov subspace methods, especially minimum residual norm methods, to solve this class of problems. As a preconditioner we consider multi-level techniques and especially focus on a two-level method. This twolevel preconditioner has shown efficient for two-dimensional applications and the purpose of this thesis is to extend this to the challenging three-dimensional case. This leads us to propose and analyze a perturbed two-level preconditioner for a flexible Krylov subspace method, where Krylov methods are used both as smoother and as approximate coarse grid solver

In this study we discuss the Vehicle Routing Problem with multiple use of vehicles (VRPM). In this variant of the routing problem the vehicles may replenish at any time at the depot. We present a detailed review of existing literature and propose two mathematical models to solve the VRPM. For these two models and their several variants we provide computational results based on the test problems taken from the literature. We also discuss a case study in which we are simultaneously dealing with side constraints such as time windows, working hour limits, backhaul customers and a heterogeneous vehicle fleet.

Cette étude s’inscrit dans le cadre de la dépollution de l’eau, elle a eu pour but d’examiner la dégradation photocatalytique d’herbicides phénylurées en solution aqueuse à pH acide, en présence d’un oxyde de fer naturel et d’acides carboxyliques. L’oxyde de fer naturel a été caractérisé par spectroscopie Raman, l’identification des produits de dégradation du fénuron et la proposition d’un mécanisme de dégradation ont été réalisées. Deux types d’irradiation ont été utilisés, i.e. l’irradiation solaire naturelle et l’irradiation par des UV générés par des lampes à vapeur de mercure. La photodégradation du fenuron en présence d’oxyde de fer naturel et l'acide oxalique obéit à une loi du premier ordre, les conditions expérimentales optimales pour ce système étaient [acide oxalique]0 = 10-3 M, [Hématite naturelle] = 0.1 g L-1 ; pH = 3. Le temps de demi-vie du fenuron est court (60 32 min) mais les résultats sont meilleurs sous irradiation solaire naturelle (30 15 min). L'acide oxalique est l’acide carboxylique le plus efficace en photodégradation du fénuron (disparition totale), l’ordre d’efficacité varie ainsi : acide oxalique > acide citrique > acide tartrique > acide malique. L’étude analytique de la dégradation du fénuron par ce procédé a permis l’identification de huit photoproduits aromatiques, de trois acides carboxyliques à courte chaîne de carbone et des ions inorganiques. Ce travail a permis de mettre en évidence le rôle de l’oxygène dissous dans le processus de dégradation du fenuron par le procédé de photo-Fenton-like, le processus ne peut pas avoir lieu en milieu désoxygéné car aucune production de H2O2 n’a été observée sous irradiation UV. L’oxygénation du milieu permet d’améliorer la capacité oxydative du procédé et d’augmenter le taux de minéralisation du carbone organique totale. En effet l’oxygénation du milieu augmente indirectement la production des radicaux hydroxyles par augmentation de la production de H2O2. Il a été mis en évidence pendant l’étude quantitative que l’oxygène était le réactif le plus consommé par ce procédé. Le traitement de la solution contenant 10-4 M de fenuron et 10-3 M d’oxalate a permis de réduire significativement la toxicité de la solution initiale après 360 minutes d’irradiation
The photodegradation of the herbicide phenylurea by using a natural iron oxide (NIO) α-Fe2O3 in aqueous solution at acidic pH has been undertaken. The NIO was characterized by the Raman spectroscopy method. The degradation pathways and the formation of by-products were studied. A high-pressure mercury lamp and sunlight were employed as light source. Fenuron photodegradation using NIO with oxalic acid followed the pseudo-first order kinetics, the optimal experimental conditions were [oxalic acid]0 = 10−3 M and [NIO] = 0.1 g L−1 at pH 3. NIO/oxalic acid/UV system led to a low fenuron half-life (32 min). The results were even better when solar light is used (15 min). The effect of four carboxylic acids; oxalic, citric, tartaric and malic acids on the degradation efficiency was studied. Oxalic acid was the most effective carboxylic acid used on the fenuron photodegradation with NIO at pH 3. The analytical study showed many aromatic intermediates, short-chain carboxylic acids and inorganic ion.The role of dissolved oxygen (DO) in degradation and mineralization of fenuron in the photo-Fenton-like system by using the NIO was also studied; the NIO was used as an iron source. The DO effect has been elucidated by carrying out experiments with and without oxygen, it has been found that the degradation and mineralization rate were strongly affected by change in DO concentration. In absence of oxygen, there is no photo-Fenton-like because of the lack of hydrogen peroxide, the degradation was caused only by the photo-reduction of Fe(III) complex in this case. Oxygenation improved the hydrogen peroxide production under irradiation. The mass balance of the reactive species showed that dissolved oxygen was the main reactive consumed during the process. The toxicity decrease with irradiation time proves that the intermediates generated during photo-oxidation by the photo-Fenton-like system by using a NIO are less toxic than fenuron

L'Internet des objets (IdO) est une technologie émergente ayant le potentiel d'améliorer notre quotidien de différentes façons. Elle consiste à étendre la connectivité au-delà des appareils standards (tels que les ordinateurs, les tablettes et les smartphones) à tous les objets du quotidien. Ces appareils, également appelés objets intelligents, peuvent alors collecter des données de leur entourage, collaborer pour les traiter puis agir sur leur environnement. Cela augmente leurs fonctionnalités et leur permet d'offrir divers services au profit de la société. Cela dit, de nombreux défis ralentissent le développement de l'IdO. La sécurisation des communications entre ces appareils est l'un des problèmes les plus difficiles qui empêche cette technologie de révéler tout son potentiel. La cryptographie fournit un ensemble de mécanismes permettant de sécuriser les données. Pour leur bon fonctionnement, ces derniers ont besoin de paramètres secrets appelés clés. La gestion des clés est une branche de la cryptographie qui englobe toutes les opérations impliquant la manipulation de ces clés : génération, stockage, distribution et remplacement. Par ailleurs, la cryptographie légère consiste à étendre les mécanismes conventionnels (la gestion des clés comprise) aux appareils à ressources limitées. Afin d'être efficaces dans l'IdO, les nouveaux mécanismes doivent offrir un bon compromis entre sécurité, performance et consommation de ressources. La gestion légère des clés est donc l'essence de la communication sécurisée dans l'IdO et le cœur de notre travail. Dans cette thèse, nous proposons un nouveau protocole léger de gestion des clés pour sécuriser la communication entre les appareils hétérogènes et dynamiques de l'IdO. Pour concevoir notre solution, nous considérons trois modes de communication : d'appareil à appareil, de groupe et de multi-groupes. Alors que la plupart des travaux connexes se concentrent uniquement sur l'un de ces modes de communication, notre solution sécurise efficacement les trois. Aussi, elle équilibre automatiquement les charges entre les appareils hétérogènes en fonction de leurs capacités. Nous prouvons alors que cela rend notre protocole plus adapté à l'IdO étant donné qu'il est efficace et hautement évolutif. De plus, nous proposons une décentralisation de notre protocole basée sur la technologie blockchain et les contrats intelligents. Ainsi, nous montrons qu'en permettant à plusieurs participants de gérer les clés cryptographiques, la décentralisation résout les problèmes de confiance, réduit le risque de défaillance du système et améliorer la sécurité. Nous implémentons enfin notre solution sur des plateformes IoT à ressources limitées qui sont basées sur le système d'exploitation Contiki. L'objectif est d'évaluer expérimentalement les performances de notre solution et de compléter nos analyses théoriques
The Internet of Things (IoT) is an emerging technology that has the potential to improveour daily lives in a number of ways. It consists of extending connectivity beyond standard devices (such as computers, tablets and smartphones) to all everyday objects. The IoT devices, also called smart objects, can collect data from their surroundings, collaborate to process them and then act on their environment. This increases their functionalities and allow them to offer various services for the benefit of society. However, many challenges are slowing down the development of the IoT. Securing communication between its devices is one of the hardest issue that prevents this technology from revealing its full potential. Cryptography provides a set of mechanisms to secure data. For their proper functioning, these mechanisms require secret parameters called keys. The Key Management is a branch of cryptography that encompasses all operations involving the handling of these of extending the conventional mechanisms (including the Key Management) to the resource-limited devices. To be efficient in the IoT, the new mechanisms must offer a good compromise between security, performance and resource requirements. Lightweight Key Management is the essence of secure communication in the IoT and the core of our work. In this thesis, we propose a novel lightweight Key Management protocol to secure communication between the heterogeneous and dynamic IoT devices. To design our solution, we consider three modes of communication: device-to-device, group and multi-group communication. While most of the related works focus only on one of these modes of communication, our solution efficiently secures all three of them. It also automatically balances the loads between the heterogeneous devices according to their capabilities. We then prove that this makes our protocol more suitable for the IoT as it is e_cient and highly scalable. Furthermore, we propose a decentralization of our protocol based on the blockchain technology and smart contracts. We show that, by empowering multiple participants to manage the cryptographic keys, decentralization solves trust issues, lowers risk of system failure and improves security. We finally implement our solution on resource-constrained IoT motes that are based on the Contiki operating system. The objective is to experimentally evaluate the performance of our solution and to complete our theoretical analyses

Abstract The world is rapidly developing into a networked society, where people, machines, data, services and applications are tightly integrated by means of information and communications technology. The members of Wireless Sensor requires solutions to support the unprecedented level of the system’s pervasion and heterogeneity, solutions which are missing today. Today’s device-level design procedures are an obstacle in the transition to this heterogeneous future, which demands diverse Internet of Things (IoT) devices, including low-end and low-power ones. Reducing the design and production costs of devices in low to mid-scale production quantities, requires new approaches to cope with application versatility. To address this problem, this thesis proposes a novel wireless sensor and actuator network (WSAN)/IoT device design methodology based on the combination of two approaches: platform-based design and autoconfiguration, that are applied to hardware (HW) and software (SW) components. Unlike the state-of-the-art methodologies, the methodology proposed enables more flexibility both during the design and after device deployment, while reducing the development expenses and time-to-market. Although neither of the two these approaches is fundamentally novel on its own, in this thesis they are employed in, and adapted to, extremely resource restricted systems. The feasibility of the methodology is shown by the development of technology artifact representing a Plug-and-Play enabled WSAN/IoT device platform. The new devices are assembled from HW modules, encapsulating the various power supply, processing, transceiver, sensor and actuator units, or sets of those. The central control unit of a device automatically identifies the HW, and configures the SW accordingly. The technology enablers for this - the HW and SW architectures and interfaces – are reported in this thesis. Experimentation confirms the viability of the proposed concepts and mechanisms. The utility of the designed solutions has been shown by a series of successful research projects and experimental results
Tiivistelmä Maailma on nopeasti muuttumassa verkottuneeksi yhteisöksi, jossa ihmiset, koneet, tiedot, palvelut ja sovellukset ovat integroituneet tiiviisti yhteen tieto- ja viestintätekniikan avulla. Tämän dynaamisen ihmisten ja koneiden välisen yhteisön jäsenillä on erilaisia ja jopa ainutlaatuisia kykyjä. Tämän vision toteutuminen edellyttää toistaiseksi puuttuvia ratkaisuja, jotka tukevat ennennäkemättömän laajalle levinnyttä ja hajanaista järjestelmää. Nykyiset laitetason suunnittelumenetelmät estävät siirtymisen tähän heterogeeniseen tulevaisuuteen, joka edellyttää monipuolisia IoT-laitteita (Internet of Things, esineiden internet), mukaan lukien yksinkertaiset ja vähän virtaa kuluttavat laitteet. Tuotantomääriltään pienten ja keskisuurten laitteiden suunnittelu- ja tuotantokustannusten vähentäminen edellyttää uusia lähestymistapoja sovellusten monipuolisuuden vuoksi. Tutkielmassa ehdotetaan tämän ongelman ratkaisuksi uutta langattomien antureiden ja toimilaitteiden verkon (WSAN) / IoT-laitteiden suunnittelumenetelmää, joka perustuu näiden kahden lähestymistavan yhdistelmään: käyttöympäristöön perustuva rakenne ja automaattinen määritys, joita sovelletaan sekä laitteisto- että ohjelmistokomponentteihin. Toisin kuin nykyiset johtavat menetelmät, ehdotettu menetelmä on joustavampi sekä suunnitteluvaiheessa että laitteen käyttöönoton jälkeen. Tämä vähentää kehityskustannuksia ja laitteen markkinoille tuomiseen tarvittavaa aikaa. Vaikka kumpikaan menetelmä ei ole lähtökohtaisesti uusi, tutkielmassa niitä käytetään järjestelmissä, joissa on äärimmäisen rajoitetut resurssit, ja ne sovitetaan niihin. Menetelmän käyttökelpoisuutta esitellään kehittämällä Plug and Play –yhteensopivaa WSAN-/IoT-laiteympäristöä edustava tekninen artefakti. Uudet laitteet kootaan laitteistomoduuleista, joissa on erilaisia virtalähteitä, prosessori-, lähetin-vastaanotin-, anturija toimilaiteyksikköjä tai niistä koostuvia kokonaisuuksia. Laitteen keskusyksikkö tunnistaa laitteiston automaattisesti ja konfiguroi sen. Tutkielmassa kerrotaan, mitä teknologiaa eli laitteisto- ja ohjelmistoarkkitehtuureja ja -rajapintoja sovelluksessa on käytetty

Accurately quantifying land-atmosphere exchanges is essential at every spatial scale, from aiding a better understanding of climate change globally to informing land management decisions at the smallest scale (e.g. agricultural land management). This quantification may be dealt with relatively easily for homogeneous land surfaces, but in the real world, landscapes are spatially heterogeneous and simple approaches are often inadequate. This thesis uses mathematically advanced methods and/or models to find robust solutions to landatmosphere exchange problems that accommodate spatial heterogeneity. A two-stage sampling strategy (2SS) was developed to reduce the uncertainties in the estimation of chamber-based GHG fluxes when sample size is inadequate to fully capture spatial heterogeneity. A Monte Carlo simulation showed that 2SS improves the estimation of soil GHG fluxes in all but the most homogeneous situations, with the improvement being directly related to the amount of spatial heterogeneity present. EC-based measurements of GHG fluxes invariably contain data gaps that require filling to generate long-term cumulative fluxes, i.e. integrating over a temporally heterogeneous timeseries. Gap-filling methods introduce uncertainty. A robust method based on image inpainting is introduced to fill gaps via a two-dimensional representation of a onedimensional data, i.e. the flux fingerprint. Results show that this unsupervised method, using a more compact and simple form, compares favourably with a widely-used traditional method and can outperform it when applied to de-noised data. The most robust measurements of surface carbon fluxes will be generated when using two independent measurement methods simultaneously. To investigate CO2 and CH4 fluxes from a heterogeneous fen, EC- and chamber-based measurements of surface carbon fluxes were implemented from 2013 to 2015. To implement a direct comparison between these measurements made at differing scales, the chamber-measured data were up-scaled, both temporally by model-based interpolations and spatially by flux footprint modelling. Results show a good linear correlation in CO2 flux and a near zero correlation in CH4 flux between methods. Further analysis on CH4 flux, however, show that the two differed only by a Gaussian distribution, implying the existence of white noise in the signal. The cumulative CO2 flux for the whole season measured by chambers was -376.5 g/m2, 33% higher than the estimated measured by EC (-281.8 g/m2). Similarly, the final cumulative CH4 flux was 4.01 g/m2 by chamber-based estimates, 43% more than EC (2.81 g/m2). The final part of this study investigates the surface flux of momentum in a structured heterogeneous land surface. A logarithmic normal distribution was developed to model the wind speed reduction around a tree-based windbreak. The model showed an excellent fit to field observations made at a real-world windbreak on farm land. A graphical method that describes a 3-d space of wind-chill temperature vs. ambient temperature and wind speed was created to quantify the potential thermal benefits gained by introducing windbreaks and reducing wind speed. The wind-chill thermal tolerance (WTT) of sheep was estimated and compared for a lowland and an upland site. Distinct differences to reduced wind speed were found between the sites, with greater thermal benefits at the upland site. The methods and models generated and developed in this study contribute to an improved quantification of land-atmosphere exchanges, and have potential to be applied to surface fluxes generally, either of mass (GHGs) or energy (heat, momentum), and to landscapes other than those dominated by vegetation. For example, the statistical idea of the two-stage sampling approach provides a generic solution to sample size deficiency in heterogeneous land surfaces; The inpainting-based gap-filling method, as an image processing technique, may be applicable to any signals that can be represented as an image, i.e. a two-dimensional space in which individual locations (pixels) have numerical attributes that can be used as RGB values; The WTT plot/analysis, used here in the context of sheep in upland sites, provides an intuitive and powerful scheme for analysing the thermal tolerance of any animal in any energetically heterogeneous landscape.

Atmospheric particles play a crucial role in climate, visibility, air pollution, and human health. Reactions between gas-phase molecules and particles (heterogeneous reactions) affect not only the particle composition and morphology, but also the composition of the atmosphere. This thesis investigates the heterogeneous chemistry of organic mixtures and inorganic solutions coated with organic monolayers as proxies for atmospheric particles. The first topic of interest was the reaction between N₂0₅ and aqueous inorganic solutions coated with organic monolayers. The goal of this work was to better understand how organic monolayers on aqueous particles affect the mass transport and kinetics of N₂0₅ uptake by aqueous aerosols, and consequently what effectthe monolayer can have on predicted concentrations of N₂0₅ in the atmosphere. To investigate heterogeneous reactions of inorganic solutions coated with an organic monolayer a new rectangular channel flow reactor was developed. This newly developed flow reactor was described in detail and validated. Subsequently, the new flow reactor was used to study the reactive uptake of N₂0₅ on sulfuric acid solutions in the presence of a variety of 1- and 2-component monolayers with varying functional groups, solubilities, chain lengths, surface pressures, and molecular surface areas. Reactive uptake of N₂0₅ on aqueous sulfuric acid solutions was found to correlate most strongly with the molecular surface area or packing density of the monolayer. These results provide a good foundation for determining the influence of monolayers on heterogeneous reactions in the atmosphere, and highlight the need for characterization of monolayer surface properties of organic monolayers present on atmospheric particles. The second topic of interest was reactions between 0₃ and proxies for meat cooking aerosols with the goal to better understand the effect of the phase and microstructure of the mixtures on the lifetime of oleic acid (OA) in atmospheric particles. The reactive uptake of 0₃ was approximately 1 order of magnitude slower on binarysolid-liquid mixtures and multicomponent mixtures that closely represent compositions of meat-cooking aerosols compared to the liquid solutions. Lifetimes up to 75 min were obtained for these mixtures.

Ce travail de thèse s'intéresse au développement de stratégies de calcul pour résoudre les problèmes de Helmholtz, en moyennes fréquences, dans les milieux hétérogènes. Il s'appuie sur l'utilisation de la Théorie Variationnelle des Rayons Complexes (TVRC), et enrichit l'espace des fonctions qu'elle utilise par des fonctions d'Airy, quand le carré de la longueur d'onde du milieu varie linéairement. Il s'intéresse aussi à une généralisation de la prédiction de la solution pour des milieux dont la longueur d'onde varie d'une quelconque autre manière. Pour cela, des approximations à l'ordre zéro et à l'ordre un sont définies, et vérifient localement les équations d'équilibre selon une certaine moyenne sur les sous domaines de calcul.Plusieurs démonstrations théoriques des performances de la méthodes sont menées, et plusieurs exemples numériques illustrent les résultats. La complexité retenue pour ces exemples montrent que l'approche retenue permet de prédire le comportement vibratoire de problèmes complexes, tel que le régime oscillatoire des vagues dans un port maritime. Ils montrent également qu'il est tout à fait envisageable de mixer les stratégies de calcul développées avec celles classiquement utilisées, telle que la méthode des éléments finis, pour construire des stratégies de calcul utilisables pour les basses et les moyennes fréquences, en même temps
This thesis develops numerical approaches to solve mid-frequency heterogeneous Helmholtz problem. When the square of wave number varies linearly in the media, one considers an extended Variational Theory of Complex Rays(VTCR) with shape functions namely Airy wave functions, which satisfy the governing equation. Then a general way to handle heterogeneous media by the Weak Trefftz Discontinuous Galerkin (WTDG) is proposed. There is no a priori restriction for the wave number. One locally develops general approximated solution of the governing equation, the gradient of the wave number being the small parameter. In this way, zero order and first order approximations are defined, namely Zero Order WTDG and First Order WTDG. Their shape functions only satisfy the local governing equation in average sense.Theoretical demonstration and academic examples of approaches are addressed. Then the extended VTCR and the WTDG are both applied to solve a harbor agitation problem. Finally, a FEM/WAVE WTDG is further developed to achieve a mix use of the Finite Element method(FEM) approximation and the wave approximation in the same subdomains, at the same time for frequency bandwidth including LF and MF

In this thesis I evaluate the departures of three common assumptions in macroeconomic modeling and estimation, namely the Rational Expectations (RE) hypothesis, the representative agent assumption and the use of first-order approximations in the estimation of dynamic stochastic general equilibrium (DSGE) models. In the first chapter I determine how the use of survey data on inflation expectations in the estimation of a model alters the evaluation of the RE assumption in comparison to an alternative assumption, namely learning. In chapter two, I use heterogeneous agent models to determine the relationship between income volatility and the demand for durable goods. In the third chapter I evaluate if the use of first-order approximations in the estimation of a model could affect the evaluation of the determinants of the Great Moderation.
En esta tesis analizo desvíos de tres supuestos comunes en la elaboración y estimación de modelos macroeconómicos. Estos supuestos son la Hipótesis de Expectativas Racionales (ER), el supuesto del Agente Representativo, y el uso de aproximaciones de primer orden en la estimación de los modelos de equilibrio general. En el primer capítulo determino como el empleo de datos de expectativas de inflación en la estimación de un modelo puede alterar la evaluación del supuesto de ER en comparación a un supuesto alternativo como learning. En el segundo capítulo, utilizo modelos de agentes heterogéneos para determinar la relación entre la volatilidad de los ingresos y la demanda de bienes durables. En el tercer capítulo, analizo si el uso de aproximaciones de primer orden afecta la evaluación de los determinantes de la Gran Moderación.

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
O acoplamento fluido-mecânico como é conhecido o efeito tanto do meio poroso no meio fluido, quanto do efeito do meio fluido no meio poroso, possui uma ampla aplicabilidade em diversos campos da engenharia, tornando-se um importante objeto de estudo. O presente trabalho analisa alguns modelos acoplados de deformação e fluxo, particularmente fluxo bifásico e acoplamento com deformação, levando-se em consideração a não linearidade física do solo. A análise de fluxo em condição bifásica pode conduzir a instabilidade, devido à característica parabólica-hiperbólica das equações governantes, bem como o método empregado para soluções das mesmas, podendo não capturar satisfatoriamente condições de heterogeneidade do meio geológico. Sendo assim, são estudadas formulações numéricas capazes de contornar essas dificuldades e ainda empregadas em condição acoplada com o problema de deformação. Emprega-se inicialmente o método dos elementos finitos, MEF, para solução do problema acoplado com fluxo bifásico, em sequência uma formulação mista em que se resolve a equação da pressão através do MEF, e intermediariamente utilizam-se métodos de melhor aproximação da velocidade como os elementos de Raviart-Thomas de mais baixa ordem e solução da equação da saturação pelo método dos volumes finitos, MVF, com esquema de interpolação de alta ordem para captura de frente de saturação. Ainda assim é apresentada uma formulação em que se emprega o método dos elementos finitos descontínuos, MEFD, apresentado em Hoteit (2008), que no presente trabalho é acoplada com o problema de deformação utilizando um procedimento staggered para solução iterativa de ambos os sistemas. São apresentados exemplos que validam as diversas formulações e que destacam as propriedades de cada uma das formulações, com vantagens e desvantagem nas suas aplicações.
The fluid-mechanical coupling is known as the effect of both the porous media in a fluid as the fluid in porous media, it has been studied intensively in past years and in recent years, given its importance in various application fields of engineering. This works studies numerical models of coupled deformation and flow, considering coupled two-phase flow and deformation, taking into account the nonlinear soil behavior. The numerical analysis of two-phase flow can lead to instabilities due to parabolic-hyperbolic character of the governing equations and the method employed does not adequately capture the heterogeneity of the geological environment. Thus, we analyze the numerical formulations capable of overcoming these difficulties and to be employed on coupled condition with deformation. Initially the finite element method, FEM, is employed for solution of the coupled two-phase flow problem. Another formulation is employed in a mixed basis, the pressure equation is solved through the FEM, solution of the equation of saturation by finite volume method, FVM, using interpolation scheme with high order to capture the saturation front. In an intermediate step, it is employing methods to better pos-processing the velocity filed as the lowest-order Raviart- Thomas finite elements. Finally, it is presented a formulation that employs the discontinuous finite element method, DFEM, presented in Hoteit et al (2008), is coupled in this work with the problem of deformation using a staggered procedure for iterative solution of the systems. Examples are presented that validate the various formulations and highlight the properties of each formulation, with advantages and disadvantages in their applications.

Магістерська дисертація на тему: «Процес гранулоутворення у псевдозрідженому шарі при застосуванні механічного диспергатора» / НТУУ «КПІ ім. Ігоря Сікорського»; Керівник Я.М. Корнієнко. – К., 2018. –с. Виконавець – М.М. Манастирний. Об’єкт дослідження: процес утворення органо-мінерально-гумінових добрив з пошаровою структурою, при зневоднені гетерогенних рідких систем із застосуванням механічного диспергатора. Предмет дослідження: кінетика процесу гранулоутворення, диспергування гетерогенних рідких систем механічним диспергатором різних конструкцій. Метою роботи є встановлення закономірностей процесу утворення органо-мінерально-гумінових добрив із заданими властивостями та розроблення ефективного обладнання. Розвинуто фізичну модель руху рідини в механічному диспергаторі конічного типу з урахуванням сил поверхневого натягу при зневодненні гетерогенних систем. Встановлено закономірність впливу конструкції диспергатора на розподілення щільності зрошення в робочому об'ємі диспергування. Експериментально визначено залежність розміру крапель від конструкції та технологічних параметрів механічного диспергатора. Експериментально визначено конфігурацію температурного поля в зоні диспергування при застосуванні механічного диспергатора конічного типу. Сформульовано базові принципи конструкції камери гранулятора із застосуванням системи введення рідкої фази через механічні диспергатори. Розроблено конструкцію конічного двокамерного механічного диспергатора.
Master's thesis on the topic: «The process of granulation in a fluidized bed with the use of mechanical disperator» / National Technical University of Ukraine Igor Sikorsky “Kyiv Polytechnic Institute”;Scientific advisorY. Korniyenko.– K., 2018. – . p. The performer – M. Manastyrnyi. The object of the research: the process of formatting an organic-mineral-humic fertilizers with a layered structure with dehydration of heterogeneous liquid systems with the use of mechanical disperator. The subject of the research: kinetics of the granulation process, dispergation of heterogeneous liquid systems by a mechanical disperser of various constructions. The aim of the work is to establish the regularities of an organic-mineral-humic fertilizers formation process with the given properties and development of efficient equipment. The physical model of fluid motion in mechanical cone-type disperator with taking into account the surface tension forces in process of heterogeneous systems dehydration is developed. The regularity of disperator's design influence on distribution of an irrigation density in the working volume of the dispergation is established. The dependence of the droplets size from the mechanical disperator's design and technological parameters is experimentally determined. The temperature field configuration in the dispergation zone with the use of mechanical conical-type disperator is experimentally determined. The basic principles of the granulator's chamber design with the use of liquid phase injection system through mechanical dispersants are formulated. The design of a conical two-chamber mechanical dispersant is developed.
Магистерская диссертация на тему: «Процесс гранулообразования в псевдоожиженном слое при применении механического диспергатора» / НТУУ «КПИ им. Игоря Сикорского»; Руководитель Я.Н. Корниенко. – К., 2018. – с.Исполнитель – М.Н. Манастырный. Объект исследования: процесс образования органо-минерально-гуминовых удобрений с послойной структурой, при обезвоженные гетерогенных жидких систем с применением механического диспергатора. Предмет исследования: кинетика процесса гранулообразования, диспергирования гетерогенных жидких систем механическими диспергаторами различных конструкций. Целью работы является установление закономерностей процесса образования органо-минерально-гуминовых удобрений с заданными свойствами и разработка эффективного оборудования. Развито физическую модель движения жидкости в механическом диспергаторе конического типа с учетом сил поверхностного натяжения при обезвоживании гетерогенных систем. Установлена закономерность влияния конструкции диспергатора на распределения плотности орошения в рабочем объеме диспергирования. Экспериментально определена зависимость размера капель от конструкции и технологических параметров механического диспергатора. Экспериментально определено конфигурацию температурного поля в зоне диспергирования при применении механического диспергатора конического типа. Сформулированы базовые принципы конструкции камеры гранулятора с применением системы ввода жидкой фазы через механические диспергаторы. Разработана конструкция конического двухкамерного механического диспергатора.

Dans cette thèse, nous présentons notre travail de recherche dans le domaine du calcul haute performance en mécanique des fluides. Avec la demande croissante de simulations à haute résolution, il est devenu important de développer des solveurs numériques pouvant tirer parti des architectures récentes comprenant des processeurs multi-cœurs et des accélérateurs. Nous nous proposons dans cette thèse de développer un solveur efficace pour la résolution sur architectures hétérogènes CPU/GPU des équations de Navier-Stokes (NS) relatives aux écoulements 3D de fluides incompressibles.Tout d'abord nous présentons un aperçu de la mécanique des fluides avec les équations de NS pour fluides incompressibles et nous présentons les méthodes numériques existantes. Nous décrivons ensuite le modèle mathématique, et la méthode numérique choisie qui repose sur une technique de prédiction-projection incrémentale.Nous obtenons une distribution équilibrée de la charge de calcul en utilisant une méthode de décomposition de domaines. Une parallélisation à deux niveaux combinée avec de la vectorisation SIMD est utilisée dans notre implémentation pour exploiter au mieux les capacités des machines multi-cœurs. Des expérimentations numériques sur différentes architectures parallèles montrent que notre solveur NS obtient des performances satisfaisantes et un bon passage à l'échelle.Pour améliorer encore la performance de notre solveur NS, nous intégrons le calcul sur GPU pour accélérer les tâches les plus coûteuses en temps de calcul. Le solveur qui en résulte peut être configuré et exécuté sur diverses architectures hétérogènes en spécifiant le nombre de processus MPI, de threads, et de GPUs.Nous incluons également dans ce manuscrit des résultats de simulations numériques pour des benchmarks conçus à partir de cas tests physiques réels. Les résultats obtenus par notre solveur sont comparés avec des résultats de référence. Notre solveur a vocation à être intégré dans une future bibliothèque de mécanique des fluides pour le calcul sur architectures parallèles CPU/GPU
In this PhD thesis, we present our research in the domain of high performance software for computational fluid dynamics (CFD). With the increasing demand of high-resolution simulations, there is a need of numerical solvers that can fully take advantage of current manycore accelerated parallel architectures. In this thesis we focus more specifically on developing an efficient parallel solver for 3D incompressible Navier-Stokes (NS) equations on heterogeneous CPU/GPU architectures. We first present an overview of the CFD domain along with the NS equations for incompressible fluid flows and existing numerical methods. We describe the mathematical model and the numerical method that we chose, based on an incremental prediction-projection method.A balanced distribution of the computational workload is obtained by using a domain decomposition method. A two-level parallelization combined with SIMD vectorization is used in our implementation to take advantage of the current distributed multicore machines. Numerical experiments on various parallel architectures show that this solver provides satisfying performance and good scalability.In order to further improve the performance of the NS solver, we integrate GPU computing to accelerate the most time-consuming tasks. The resulting solver can be configured for running on various heterogeneous architectures by specifying explicitly the numbers of MPI processes, threads and GPUs. This thesis manuscript also includes simulation results for two benchmarks designed from real physical cases. The computed solutions are compared with existing reference results. The code developed in this work will be the base for a future CFD library for parallel CPU/GPU computations

Dans cette thèse, des simulations DFT-MD couplées à des techniques inno-vantes de métadynamique, sont appliquées pour acquérir une compréhensionglobale des interfaces aqueuses d'oxyde de cobalt Co3O4 et CoO(OH) dansla catalyse de la réaction d'évolution de l'oxygène (OER), et ainsi éventuellement aider à la conception de nouveaux catalyseurs basés sur des matériaux non précieux, un domaine clé de la recherche scientifique et technologique, particulièrement important pour l'économie de l'hydrogène, pour les technologies vertes dans une période de temps avec une demande toujours plus croissanteen énergie verte. Dans cette thèse, nous révélons étape par étape les mécanismes de l'OER sur les électrocatalyseurs aqueux d'oxyde de cobalt Co3O4 etCoO(OH) via de nouvelles techniques de métadynamique.Jusqu'à présent, la littérature n'a jamais pris en compte les modificationsau niveau atomique de la structure des électrodes ainsi que de l'eau interfaciale dans leur modélisation des processus OER. Ce manque de connaissances représente clairement un obstacle important au développement de catalyseurs améliorés, qui pourrait être surmonté en utilisant des méthodes capables de suivre les caractéristiques catalytiques de l'OER à l'échelle atomique. Pour la première fois, nous montrons combien il est important de prendre en considération la présence de l'environnement aqueux dans la caractérisation structurale des surfaces du catalyseur, c'est-à-dire (110)-Co3O4 et (0001)-CoO(OH) dans ce travail. Une caractérisation détaillée des propriétés chimiques et physiques des interfaces aqueuses est fournie (la structure, la dynamique, la spectroscopie, le champ électrique), pour les surfaces (110)-Co3O4 et (0001)-CoO(OH) en contact avec l'eau liquide.Une étude détaillée de l'OER est présentée non seulement du point de vue descatalyseurs, mais aussi en abordant le rôle de l'environnement de l'eau dans leprocessus catalytique, ce qui n'a pas été fait auparavant dans la littérature. En conséquence, l'OER en phase gazeuse et en phase liquide sont étudiés ici auxinterfaces aqueuses (110)-Co3O4 et (0001)-CoO(OH) en adoptant une nouvelleapproche de métadynamique d'échantillonnage amélioré, capable d'identifieret caractériser les mécanismes de réaction chimique et d'intégrer pleinement lerôle des degrés de liberté du solvant, permettant ainsi de dévoiler des réactivités chimiques d'une complexité remarquable. L'énergétique, la cinétique et la thermodynamique derrière l'OER sont donc trouvées à ces surfaces d'oxyde de cobalt à l'interface avec l'eau
In this thesis, DFT-MD simulations, coupled with state-of-the-art metadynamics techniques, are applied to gain a global understanding of Co3O4 and CoO(OH) cobalt oxide aqueous interfaces in catalyzing the oxygen evolution reaction (OER), and hence possibly help in the design of novel catalysts basedon non-precious materials, a current key field of research in science and technology, especially of importance for the hydrogen economy, for green technology in a period of time with an ever more growing demand in green-energy. In this thesis, we step-by-step reveal the OER mechanisms on spinel Co3O4 andCoO(OH) cobalt aqueous electrocatalysts carefully and rationally via novelmetadynamics techniques.Up to now, the literature has never taken into account the atomistic modifications on the electrode structure as well as on the interfacial water into their modeling of OER processes. Such lack of knowledge clearly represents a significant hurdle toward the development of improved catalysts, which couldbe overcome by employing methods able to track the catalytic features of theOER at the atomistic scale. For the first time, we show how important itis to take into consideration the presence of the liquid water environment inthe structural characterization of catalyst surfaces, i.e. for (110)-Co3O4 and(0001)-CoO(OH) in this work. A detailed characterization of chemical andphysical properties of the aqueous interfaces is provided (i.e. structure, dynamics, spectroscopy, electric field), for the (110)-Co3O4 and (0001)-CoO(OH)aqueous surfaces.A study of the OER is presented not only by looking at the catalysts, butalso by addressing the role of the water environment in the catalytic process,not done before in literature. Accordingly, both gas-phase and liquid-phaseOER are here investigated at the (110)-Co3O4 and (0001)-CoO(OH) adoptinga novel enhanced sampling metadynamics approach able to address a widerange of chemical reaction mechanisms and to fully include the role of thesolvent degrees of freedom, allowing to unveil reaction networks of remarkablecomplexity. The energetics, kinetics and thermodynamics behind the OER aretherefore found at these cobalt oxide surfaces

Дисертаційна робота присвячена встановленню закономірностей формування кристалічної структури і фазового складу, проходження дифузійних процесів, поведінки електрофізичних (питомий опір), магніторезистивних (анізотропний і гігантський магнітоопір) та магнітних (коерцитивна сила, поле насичення) властивостей і їх взаємозв’язку для чутливих елементів плівкoвих сенсoрів на основі Co, Fe, FeхNi100-х та Cu в інтервалі товщин d = 10–50 нм і концентрацій х = 10–90 % у температурному інтервалі 120–700 К. Установлено закономірності в польових залежностях анізотропного та гігантського магнітоопору для магнітонеоднорідних плівкових матеріалів із різною товщиною та концентрацією компонент магнітних, немагнітних і додаткових шарів. Досліджено розмірні концентраційні й температурні залежності величини ізотропного магнітоопору та магнітних параметрів, а також розраховано чутливість магнітоопору плівкових систем до магнітного поля. Експериментально досліджений і теоретично проаналізований із використанням феноменологічного підходу (резисторної та двострумової моделей) ефект гігантського магнітоопору в тришарових плівках. Уперше одержано аналітичні вирази для розрахунку параметра спінової асиметрії та опору високоомного спінового каналу. Досліджено залежності величини ефекту анізотропного гігантського магнітоопору від товщини покривного магнітного шару. Розраховано параметр асиметрії, що характеризує відмінність довжин вільного пробігу електронів у спінових каналах провідності для поздовжньої та поперечної геометрій вимірювання магнітоопору. Вивчені фізичні прoцеси в плівкoвих матеріалах із тoчки зoру їх мoжливoгo застoсування як чутливих елементів із високою температурною і часовою стабільністю багатoфункціoнальних сенсoрних та інфoрмаційних приладів різнoгo призначення.
Диссертационная работа посвящена установлению закономерностей формирования кристаллической структуры и фазового состава, изучению диффузионных процессов, поведения электрофизических (удельное сопротивление), магниторезистивных (анизотропное и гигантское магнитосопротивление) и магнитных (коэрцитивная сила, поле насыщения) свойств и их взаимосвязи для чувствительных элементов пленочных сенсоров на основе Co, Fe, FeхNi100-х и Cu в интервале толщин d = 10–50 нм и концентраций х = 10–90 % в температурном интервале 120–700 К. Установленно закономерности в полевых зависимостях анизотропного и гигантского магнитосопротивления для магнитонеоднородных пленочных материалов с разной толщиной и концентрацией компонент магнитных, немагнитных и дополнительных слоев. Исследованно размерные концентрационные и температурные зависимости величины изотропного магнитосопротивления и магнитных параметров, а также рассчитана чувствительность магнитосопротивления пленочных систем к магнитному полю. Экспериментально исследован и теоретически проанализирован с использованием феноменологического подхода (резисторной и двутоковой моделей) эффект гигантского магнитосопротивления в трехслойных пленках. Впервые получены аналитические выражения для расчета параметра спиновой асимметрии и сопротивления высокоомного спинового канала. Исследованно зависимости величины эффекта анизотропного гигантского магнитосопротивления от толщины покрывающего магнитного слоя. Рассчитан параметр асимметрии, характеризирующий отличие длин свободного пробега электронов в спиновых каналах проводимости для продольной и поперечной геометрий измерения магнитосопротивления. Изучены физические прoцессы в пленочных материалах с тoчки зрения их возможного применения как чувствительных элементов с высокой температурной и временной стабильностью в многофункциональных сенсoрных и информационных приборах различного назначения.
This thesis is devoted to the establishment of the general trend in the formation of crystal structure and phase composition; analysis of the diffusion processes, electrophysical (resistivity), magnetoresistive (anisotropic and giant magnetoresistance), and magnetic (coercivity, saturation field) properties behavior, and their correlation for three-layer and multilayer films based on Co, Fe, FeхNi100-x, and Cu in the range of thickness d = 10–50 nm and concentration x = 10–90 % in the temperature range 120–700 K. The general trend in field dependences of anisotropic and giant magnetoresistance for magneto-heterogeneous thin film materials with different thickness and concentration of magnetic, non-magnetic and additional layers determined. Size, concentration, and temperature dependences of the isotropic magnetoresistance value and magnetic parameters investigated. The sensibility of magnetoresistance of thin film systems to magnetic field calculated. The giant magnetoresistive effect in the triple-layered films was experimentally investigated and theoretically analyzed. The first time the analytical expressions for calculation of the parameters of spin-skewers and resistance of the high-resistance spin channel were received. Dependences of the anisotropic giant magnetoresistance value vs. the thickness of the covered magnetic layer investigated. The parameters of asymmetric that characterized the difference of electron mean free path in the spin channel of conductance for longitudinal and transverse geometries of magnetoresistance measurements calculated. Physical processes in thin films materials studied from the point of view of their practical application as sensitive elements with high temperature and time stability of multifunctional sensory and information devices for a various setting.

Les travaux de cette thèse portent sur des méthodes de volumes finis sur maillages quelconque pour la discrétisation de problèmes d'évolution non linéaires modélisant le transport de contaminants en milieu poreux et les écoulements diphasiques.Au Chapitre 1, nous étudions une famille de schémas numériques pour la discrétisation d'une équation parabolique dégénérée de convection-reaction-diffusion modélisant le transport de contaminants dans un milieu poreux qui peut être hétérogène et anisotrope. La discrétisation du terme de diffusion est basée sur une famille de méthodes qui regroupe les schémas de volumes finis hybrides, de différences finies mimétiques et de volumes finis mixtes. Le terme de convection est traité à l'aide d'une famille de méthodes qui s'appuient sur les inconnues hybrides associées aux interfaces du maillage. Cette famille contient à la fois les schémas centré et amont. Les schémas que nous étudions permettent une discrétisation localement conservative des termes d'ordre un et d'ordre deux sur des maillages arbitraires en dimensions d'espace deux et trois. Nous démontrons qu'il existe une solution unique du problème discret qui converge vers la solution du problème continu et nous présentons des résultats numériques en dimensions d'espace deux et trois, en nous appuyant sur des maillages adaptatifs.Au Chapitre 2, nous proposons un schéma de volumes finis hybrides pour la discrétisation d'un problème d'écoulement diphasique incompressible et immiscible en milieu poreux. On suppose que ce problème a la forme d'une équation parabolique dégénérée de convection-diffusion en saturation couplée à une équation uniformément elliptique en pression. On considère un schéma implicite en temps, où les flux diffusifs sont discrétisés par la méthode des volumes finis hybride, ce qui permet de pouvoir traiter le cas d'un tenseur de perméabilité anisotrope et hétérogène sur un maillage très général, et l'on s'appuie sur un schéma de Godunov pour la discrétisation des flux convectifs, qui peuvent être non monotones et discontinus par rapport aux variables spatiales. On démontre l'existence d'une solution discrète, dont une sous-suite converge vers une solution faible du problème continu. On présente finalement des cas test bidimensionnels.Le Chapitre 3 porte sur un problème d'écoulement diphasique, dans lequel la courbe de pression capillaire admet des discontinuité spatiales. Plus précisément on suppose que l'écoulement prend place dans deux régions du sol aux propriétés très différentes, et l'on suppose que la loi de pression capillaire est discontinue en espace à la frontière entre les deux régions, si bien que la saturation de l'huile et la pression globale sont discontinues à travers cette frontière avec des conditions de raccord non linéaires à l'interface. On discrétise le problème à l'aide d'un schéma, qui coïncide avec un schéma de volumes finis standard dans chacune des deux régions, et on démontre la convergence d'une solution approchée vers une solution faible du problème continu. Les test numériques présentés à la fin du chapitre montrent que le schéma permet de reproduire le phénomène de piégeage de la phase huile.

Ao longo dos últimos anos tem vindo a haver um aumento da atenção dada à recolha de informação e extração de conhecimento. Desenvolvimentos recentes nas áreas de armazenamento de dados, sistemas distribuídos e paralelização fizeram com que a análise de vastas quantidades de informação se tornasse mais direta. No entanto, apesar do processamento de grandes quantidades de informação ser mais simples ainda existem alguns problemas que necessitam ser adereçados. Um destes problemas está localizado na limpeza da informação que é recolhida, ou seja a transformação da informação num formato mais simples para a extração de conhecimento.Normalmente, este problema é abordado com o desenvolvimento de uma solução específica para cada caso, sem a capacidade de ser generalizada. Como esperado, este tipo de solução funciona bem num ambiente onde os dados são bem conhecidos e possuem uma estrutura fixa, mas se existir uma alteração na estrutura inicial ou final da informação é necessário fazer um ajuste à solução. Esta situação traz mais complexidade, o que pode causar um aumento de dificuldade na manutenção e desenvolvimento de novas funcionalidades numa aplicação.A solução que está a ser analisada nesta dissertação é o desenvolvimento de uma aplicação onde um utilizador pode agregar e transformar informação que origina de fontes de informação diferentes. Esta capacidade é conseguida através da utilização de documentos definidos pelo utilizador para que uma modificação no sistema implique o mínimo de impacto para o utilizador final.Esta solução vai ser testada num ambiente real de forma a melhor testar a usabilidade desta. O cenário baseia-se numa aplicação que extrai informação de várias fontes de informação e, de momento, necessita de diversos módulos diferentes para fazer a transformação de informação da sua estrutura inicial para uma mais adequada.
Over the last few years there has been an increase in the attention given to both data collection and knowledge extraction. Recent developments in data storage, distributed systems and parallelization made the analysis of vast amounts of data more straightforward. However, whilst processing large quantities of information has been made simpler there are still some problems that need to be addressed. One of these problems resides in the clean-up of the data collected, meaning the transformation of the information collected into a more useful format from where knowledge can be extracted.Usually this problem is addressed by developing a solution on a case by case basis that has no power of generalization. As expected, this type of solution works well in an environment where the data is well known and with a fixed structure, but if there are changes in the initial structure or the final structure of the information there needs to be an adjustment made to the solution. This brings added complexity that can cause an application to become increasingly difficult to maintain and add new features.The solution that is analyzed throughout this dissertation work is the creation of an application where a user can combine and transform information that originates from different sources. This is made utilizing user-defined configuration documents, so that when a change is made in the system the impact for the end-user is minimized.In order to better test the suitability of the solution, it is going to be developed using a real-world scenario. This scenario is based on an already existing application that collects information from a variety of sources and has the necessity of transforming the information collected into a more useful structure.

Ao longo dos últimos anos tem vindo a haver um aumento da atenção dada à recolha de informação e extração de conhecimento. Desenvolvimentos recentes nas áreas de armazenamento de dados, sistemas distribuídos e paralelização fizeram com que a análise de vastas quantidades de informação se tornasse mais direta. No entanto, apesar do processamento de grandes quantidades de informação ser mais simples ainda existem alguns problemas que necessitam ser adereçados. Um destes problemas está localizado na limpeza da informação que é recolhida, ou seja a transformação da informação num formato mais simples para a extração de conhecimento.Normalmente, este problema é abordado com o desenvolvimento de uma solução específica para cada caso, sem a capacidade de ser generalizada. Como esperado, este tipo de solução funciona bem num ambiente onde os dados são bem conhecidos e possuem uma estrutura fixa, mas se existir uma alteração na estrutura inicial ou final da informação é necessário fazer um ajuste à solução. Esta situação traz mais complexidade, o que pode causar um aumento de dificuldade na manutenção e desenvolvimento de novas funcionalidades numa aplicação.A solução que está a ser analisada nesta dissertação é o desenvolvimento de uma aplicação onde um utilizador pode agregar e transformar informação que origina de fontes de informação diferentes. Esta capacidade é conseguida através da utilização de documentos definidos pelo utilizador para que uma modificação no sistema implique o mínimo de impacto para o utilizador final.Esta solução vai ser testada num ambiente real de forma a melhor testar a usabilidade desta. O cenário baseia-se numa aplicação que extrai informação de várias fontes de informação e, de momento, necessita de diversos módulos diferentes para fazer a transformação de informação da sua estrutura inicial para uma mais adequada.
Over the last few years there has been an increase in the attention given to both data collection and knowledge extraction. Recent developments in data storage, distributed systems and parallelization made the analysis of vast amounts of data more straightforward. However, whilst processing large quantities of information has been made simpler there are still some problems that need to be addressed. One of these problems resides in the clean-up of the data collected, meaning the transformation of the information collected into a more useful format from where knowledge can be extracted.Usually this problem is addressed by developing a solution on a case by case basis that has no power of generalization. As expected, this type of solution works well in an environment where the data is well known and with a fixed structure, but if there are changes in the initial structure or the final structure of the information there needs to be an adjustment made to the solution. This brings added complexity that can cause an application to become increasingly difficult to maintain and add new features.The solution that is analyzed throughout this dissertation work is the creation of an application where a user can combine and transform information that originates from different sources. This is made utilizing user-defined configuration documents, so that when a change is made in the system the impact for the end-user is minimized.In order to better test the suitability of the solution, it is going to be developed using a real-world scenario. This scenario is based on an already existing application that collects information from a variety of sources and has the necessity of transforming the information collected into a more useful structure.

碩士
國立交通大學
環境工程所
87
The objective of this study is to establish the Heterogeneous Catalytic Ozonation System. It is attempted to combine ozone with the adsorptive and oxidative properties of solid metal oxide catalysts to mineralize dissolved organics at 25℃. 2-Chlorophenol and oxalic acid were selected as the target organics. The influence of catalyst dosages, catalyst species and pH values had been examined. The analysis of reaction rate, mineralization efficiency, ozone consumption and toxicity were carried out during the whole experiment in order to evaluate the performance of this system. Under neutral condition, ozonation in the presence of alumina exhibited the greatest enhancement in mineralizing 2-chlorophenol(from 22% to 43% ). The consumption of ozone was half of the conventional system, and the reduction of toxicity was steadier. In addition, three consecutive runs with the catalyst revealed the log-term stability of the catalyst. Ozonation of oxalic acid aqueous solution in presence of MnO2 supported on alumina under acidic condition revealed the great mineralization efficiency. It is suggested that some of the manganate ions participated in this reaction resulting in the increase in reaction rate.

Several advancements related to the solution of 3D time-harmonic wave equations are presented, especially in the context of a parallel moving-PML sweeping preconditioner for problems without large-scale resonances. The main contribution of this dissertation is the introduction of an efficient parallel sweeping preconditioner and its subsequent application to several challenging velocity models. For instance, 3D seismic problems approaching a billion degrees of freedom have been solved in just a few minutes using several thousand processors. The setup and application costs of the sequential algorithm were also respectively refined to O(γ^2 N^(4/3)) and O(γ N log N), where N denotes the total number of degrees of freedom in the 3D volume and γ(ω) denotes the modestly frequency-dependent number of grid points per Perfectly Matched Layer discretization. Furthermore, high-performance parallel algorithms are proposed for performing multifrontal triangular solves with many right-hand sides, and a custom compression scheme is introduced which builds upon the translation invariance of free-space Green’s functions in order to justify the replacement of each dense matrix within a certain modified multifrontal method with the sum of a small number of Kronecker products. For the sake of reproducibility, every algorithm exercised within this dissertation is made available as part of the open source packages Clique and Parallel Sweeping Preconditioner (PSP).
text

Many online services access a large number of autonomous data sources and at the same time need to meet different user requirements. It is essential for these services to achieve semantic interoperability among these information exchange entities. In the presence of an increasing number of proprietary business processes, heterogeneous data standards, and diverse user requirements, it is critical that the services are implemented using adaptable, extensible, and scalable technology. The COntext INterchange (COIN) approach, inspired by similar goals of the Semantic Web, provides a robust solution. In this paper, we describe how COIN can be used to implement dynamic online services where semantic differences are reconciled on the fly. We show that COIN is flexible and scalable by comparing it with several conventional approaches. With a given ontology, the number of conversions in COIN is quadratic to the semantic aspect that has the largest number of distinctions. These semantic aspects are modeled as modifiers in a conceptual ontology; in most cases the number of conversions is linear with the number of modifiers, which is significantly smaller than traditional hard-wiring middleware approach where the number of conversion programs is quadratic to the number of sources and data receivers. In the example scenario in the paper, the COIN approach needs only 5 conversions to be defined while traditional approaches require 20,000 to 100 million. COIN achieves this scalability by automatically composing all the comprehensive conversions from a small number of declaratively defined sub-conversions.
Singapore-MIT Alliance (SMA)

碩士
國立交通大學
環境工程系所
99
The coastal leaky aquifer system includes an unconfined aquifer on the top, a confined aquifer at the bottom, and an aquitard in between. This aquifer system was usually assumed to be homogeneous and of an infinite extent in the horizontal direction. The aquifer system may however be heterogeneous due to depositional and post depositional processes. This study considers that the aquitard and confined aquifer are heterogeneous and both formations are divided into several homogeneous regions. A one-dimensional analytical model is developed for describing the head fluctuation in such a heterogeneous leaky aquifer system. The water table of the upper unconfined aquifer is maintained constant. It is revealed that both the length increasing and location nearing coast line of the heterogeneous aquitard have significant decreasing on the amplitude and increasing phase shift of the head fluctuation in the confined aquifer. Besides, this study indicates a heterogeneous trending confined aquifer may probably cause a shorter tidal intrusion distance and lower head distribution in a coastal leaky aquifer system.

Doctoral dissertation for PhD degree in Chemical and Biological Engineering
The work developed during this thesis presents an eco-friendly alternative process that allows simultaneously the decontamination of metal-containing wastewater and the oxidation of volatile organic compounds present in gaseous streams. A combined biosorption system consisting of a bacterium, Arthrobacter viscosus, supported on zeolites was thoroughly studied on the removal of metals from aqueous solutions. After the biosorption, the metalloaded zeolites were successfully reutilized as catalysts in the oxidation of volatile organic compounds (VOC). In chapter 2, the biosorption of Cr(III) and Cr(VI) in single metal solutions by the combined system, bacteria/NaY zeolite, was evaluated. Experiments were performed with initial concentration of Cr(III) or Cr(VI) between 10 and 100 mg/L and biomass concentration of 0.3 g/L. The solution pH was not controlled during these experiments. Cr(III) cationic species were easily removed from solution by ion exchange, since zeolites have strong affinity for transition metal cations. However, the lack of affinity of the zeolite for Cr(VI) anionic species was overcome by the action of the bacterium that performed its reduction to Cr(III), followed by ion exchange in the zeolite. The best uptake of chromium by the combined system was achieved for initial concentration of 100 mg/L: 14 mgCr/gzeolite for Cr(III) and 3 mgCr/gzeolite for Cr(VI). In chapter 3, the removal of iron and chromium from binary aqueous solutions of Fe(III)/Cr(III) and Fe(III)/Cr(VI) by A. viscosus supported on NaY zeolite was evaluated. The biosorption assays were conducted with initial concentration of both metals of 10, 25 and 40 mg/L and biomass concentration of 0.3 g/L. The solution pH was not adjusted during the experiments. The removal efficiencies of iron and chromium were generally improved when the bacterium was supported on the zeolite, in comparison with suspended bacteria. The supported system was selective towards Fe(III) in the presence of Cr(VI), due to its positive charge. However, in binary solutions of Fe(III)/Cr(III), similar affinity to Fe(III) and Cr(III) was observed, as both metals are in the form of cations. In chapter 4, several experimental parameters were optimized in order to improve the reduction of Cr(VI) performed by the bacterium and the uptake of chromium by the supported system. The biosorption assays were performed under different operating conditions of solution pH (1, 2, 3 and 4), biomass concentration (1, 2, 4 and 5 g/L) and initial Cr(VI) concentration (10, 25, 50, 75 and 100 mg/L). The results revealed that the solution pH was the most important parameter that affected the biosorption of Cr(VI) and the optimum pH value was found to be 4. This pH value was the result of two opposite trends, since the reduction of Cr(VI) was favored by very acidic solutions, while the uptake of total Cr was enhanced by higher pH values. XPS analysis of the bacterial surface revealed that the chromium entrapped on the biomass was in the trivalent form, which is an evidence that the biosorption mechanism of Cr(VI) performed by the bacterium was an adsorption-coupled reduction process. The highest uptake value and chromium content in NaY zeolite, 13 mgCr/gzeolite and 0.90 % (w/w), respectively, were achieved at pH 4, biomass concentration of 5 g/L and initial Cr(VI) concentration of 100 mg/L. The characterization analyses revealed that Cr-Y zeolite obtained at pH 4 was the most suitable to be used as catalyst due to its higher content of chromium and maintenance of the structural, morphological and textural properties in comparison with the starting NaY zeolite. In chapter 5, Cr-Y zeolite obtained after biosorption at pH 4, was successfully reutilized as catalyst in the oxidation of ethyl acetate, ethanol and toluene. For all VOC tested, the presence of chromium in the zeolite shifted the reaction pathways, allowing a significant increase of activity and selectivity towards CO2, in comparison with the starting NaY zeolite. In terms of VOC conversion, the following sequence was observed: ethanol > ethyl acetate > toluene. With regard to CO2 production, ethyl acetate was the only compound for which total oxidation was achieved. Thus, in terms of selectivity towards CO2 the sequence changes to ethyl acetate > toluene > ethanol. In chapter 6, the performance of A. viscosus supported on Y and ZSM5 zeolites, previously modified by ion exchange with NaNO3, was investigated on Cr(VI) biosorption. Y zeolites presented higher efficiencies of chromium removal due to their higher ion exchange capacity in comparison with ZSM5 zeolites. After the biosorption of Cr(VI), the different chromiumloaded zeolites were successfully reused as catalysts in the oxidation of ethyl acetate. The ZSM5 catalysts showed higher activity and selectivity towards CO2 than Y zeolites. The results revealed that ZSM5 zeolites, due to their different framework structure and textural properties, as well as due to their lower acidity, are more active for ethyl acetate oxidation than Y zeolites. Finally, no significant changes were observed in the catalytic behaviour of Y and ZSM5 catalysts with different content of sodium, which is an indication that the extension of sodium exchange did not affect substantially the catalytic properties of the zeolites.
O trabalho desenvolvido ao longo desta tese apresenta uma metodologia alternativa e ecológica que permite simultaneamente o tratamento de efluentes líquidos contaminados com metais, assim como a oxidação de compostos orgânicos voláteis presentes em correntes gasosas. Procedeu-se ao estudo de um sistema de biossorção combinado, constituído por bactérias da espécie Arthrobacter viscosus suportadas em zeólitos, na remoção de metais de soluções aquosas. Depois dos ensaios de biossorção, os zeólitos carregados com metal foram reutilizados como catalisadores na oxidação de compostos orgânicos voláteis (VOC). No capítulo 2 foi estudada a biossorção de Cr(III) e Cr(VI), em soluções monometálicas, pelo sistema combinado bactéria/zeólito NaY. Foram realizados ensaios com concentrações iniciais de Cr(III) ou Cr(VI) entre 10 e 100 mg/L e concentração de biomassa de 0.3 g/L. Durante estes ensaios não se procedeu ao controlo do pH da solução. As espécies catiónicas de crómio trivalente foram facilmente removidas da solução por permuta iónica, uma vez que os zeólitos possuem grande afinidade para catiões de metais de transição. No entanto, a baixa afinidade dos zeólitos para as espécies aniónicas de crómio hexavalente foi ultrapassada pela acção da bactéria que promoveu a redução de Cr(VI) a Cr(III), sendo este último permutado pelo zeólito. Os melhores valores de uptake foram obtidos para uma concentração inicial de 100 mg/L: 14 mgCr/gzeólito para o Cr(III) e 3 mgCr/gzeólito para o Cr(VI). No capítulo 3 avaliou-se a remoção de crómio e ferro de soluções binárias de Fe(III)/Cr(III) e Fe(III)/Cr(VI) pelo sistema combinado bactéria/zeólito NaY. Os ensaios de biossorção foram realizados com concentrações iniciais de ambos os metais de 10, 25 e 40 mg/L, e concentração de biomassa de 0.3 g/L. Também nestes ensaios não foi controlado o pH da solução. As eficiências de remoção de ferro e crómio foram, no geral, melhoradas para o sistema suportado, em comparação com bactérias em suspensão. O sistema suportado foi selectivo para o Fe(III) na presença de Cr(VI), devido à sua carga positiva. Por sua vez, em soluções binárias de Fe(III)/Cr(III), o sistema combinado revelou igual afinidade para o Fe(III) e o Cr(III), uma vez que ambos os metais se apresentam na forma catiónica. No capítulo 4 foram optimizados diversos parâmetros experimentais com o objectivo de promover a redução de Cr(VI) levada a cabo pela bactéria, assim como o uptake de crómio pelo sistema combinado. Os estudos de biossorção foram realizados com diferentes condições de pH (1, 2, 3 e 4), concentração de biomassa (1, 2, 4 e 5 g/L) e concentração inicial de Cr(VI) (10, 25, 50, 75 e 100 mg/L). Os resultados revelaram que o pH da solução foi o parâmetro que mais influenciou a biossorção de Cr(VI), tendo sido encontrado um pH óptimo igual a 4. Este valor de pH foi o resultado de duas tendências opostas: a redução de Cr(VI) foi favorecida em soluções muito ácidas, enquanto que a remoção de Cr total foi promovida para valores de pH superiores. A análise por XPS da superfície da bactéria revelou que o crómio presente na biomassa estava na forma trivalente, o que é uma evidência de que o mecanismo de biossorção promovido pela bactéria é um processo que combina fenómenos de adsorção e de redução. O valor mais elevado de uptake e de teor de crómio no zeólito, 13 mgCr/gzeólito e 0.9 % (m/m), respectivamente, foram obtidos para o ensaio a pH 4, concentração de biomassa de 5 g/L e concentração inicial de Cr(VI) de 100 mg/L. As técnicas de caracterização mostraram que o zeólito Cr-Y obtido a pH 4 revelou ser o mais adequado para ser utilizado como catalisador devido ao seu elevado teor de crómio e à conservação das propriedades estruturais, morfológicas e texturais em comparação com o zeólito de partida NaY. No capítulo 5, o zeólito Cr-Y obtido após a biossorção a pH 4 foi reutilizado com sucesso como catalisador na oxidação do acetato de etilo, do etanol e do tolueno. Para todos os VOC testados, a presença de crómio no zeólito alterou os mecanismos de reacção, assim como conduziu a uma melhoria significativa da actividade e selectividade para o CO2, em comparação com o zeólito de partida NaY. Em termos de conversão de VOC, foi observada a seguinte sequência: etanol > acetato de etilo > tolueno. Em termos de produção de CO2, apenas para o acetato de etilo se verificou a oxidação completa. Assim, em termos de selectividade para o CO2 verificou-se a sequência: acetato de etilo > tolueno > etanol. No capítulo 6 estudou-se a biossorção de Cr(VI) pelo sistema combinado, utilizando-se diferentes zeólitos Y e ZSM5, previamente modificados por permuta iónica com NaNO3. Os zeólitos Y apresentaram eficiências de remoção de crómio superiores, devido à sua maior capacidade de troca iónica em comparação com os zeólitos ZSM5. Os diferentes zeólitos contendo crómio foram reutilizados com sucesso na oxidação catalítica do acetato de etilo. Os zeólitos ZSM5 mostraram-se mais activos e selectivos para o CO2 do que os zeólitos Y. A maior actividade dos zeólitos ZSM5 na oxidação do acetato de etilo deveu-se à sua diferente estrutura e propriedades texturais, assim como à sua menor acidez. Por fim, não se registaram diferenças significativas no comportamento catalítico dos zeólitos Y e ZSM5 contendo diferentes teores de sódio, o que é uma indicação de que a extensão da permuta iónica com sódio não afectou substancialmente as propriedades catalíticas dos zeólitos.

博士
國立清華大學
資訊工程學系
98
A heterogeneous multi-processor (HeMP) system consists of several heterogeneous processors, each of which is specially designed to deliver the best energy-saving performance for a particular category of applications. A low power real-time scheduling algorithm is required to schedule tasks on such a system to minimize its energy consumption and complete all tasks by their deadlines. Existing works assume that processor speeds are known as a priori and cannot deliver the optimal energy-saving performance. The problem of determining the optimal voltage for each processor in order to minimize the total energy consumption is called the voltage setup problem. To the best of our knowledge, this study is the first work to propose the optimal solution for the HeMP single-level voltage setup problem. We first formulate the problem as a non-linear generalized assignment problem that has been proved to be NP-hard. We next develop a pruning-based algorithm to obtain the optimal solution. A heuristic algorithm is also proposed to derive an approximate solution. In our simulations, we model more than several dozen of off-the-shelf embedded processors including ARM and TI DSP processors. The results show that the pruning-based algorithm reduces the time usually needed for an exhaustive search to derive the optimal solution by at least 98%. Also, our heuristic algorithm achieves a minimum energy consumption in comparison with existing research.

碩士
國立成功大學
尖端材料國際碩士學位學程
105
Through the years, the demand for renewable sources of energy increases significantly as we are facing serious problems with safety hazards, air and land pollution, global warming and many other ecological complications. Biodiesel is an alternative diesel fuel derived from animal fats or vegetable oils. It is purely biodegradable, non-toxic and sustainable. Biodiesel is made from the process called transesterification wherein animal fats or vegetable oils (triglyceride) are mixed with alcohol, and with an aid of a catalyst, will produce biodiesel and glycerol. For this study, we focused our research on the catalyst, a heterogeneous basic catalyst to be specific. One of the drawbacks of using basic catalyst is the low biodiesel yield due to soap formation and lack of reusability due to serious problems of leaching. The goal was to develop a catalyst that will hinder soap formation and leaching during transesterification. We also wanted to determine the effects of single-phase versus two-phase oxides using CaxSr1-xO system. In this study, we performed three various methods for catalyst synthesis – Co-Precipitation (CP), Solid State Sintering (SSS) and Polymer Complex Method (PCM). It was found out that PCM is the best method for synthesizing a high purity and homogeneous sample due to atoms mixed atomistically rather than just surface reactions for solid state sintering. PCM offers more purity than co-precipitation since the chelating agent catches the cations, which ensures random mixing and homogeneity. Single phase Ca0.2Sr0.8O, exhibited the highest yield amongst all the catalysts. However, the two-phase system has stabilized the yield within its range. Leaching was also decreased within the two-phase region, as well as the particle size of the catalysts. It was also found out that Sr(OH)2 contributes significantly to the biodiesel conversion.

碩士
華梵大學
哲學系碩士班
96
The modernity has two sides. On the one hand, the modernity emphasizes science and progress, enlighten. Habermas said: “The modernity is an incomplete project.” On the other hand, modernity brings many problems and makes a anomy to society. The social in Taiwan , pre-modernity、modernity and post-modernity to exert an influence, and make some problems. The person who lives in Taiwan can feel that the social to be in fragmentary situation. This paper tries to find the source of these problems and find possible to solve these problems. The purposive of this paper try to find a way to attain the social integration through the communicative action.

abstract: The rapid advances in wireless communications and networking have given rise to a number of emerging heterogeneous wireless and mobile networks along with novel networking paradigms, including wireless sensor networks, mobile crowdsourcing, and mobile social networking. While offering promising solutions to a wide range of new applications, their widespread adoption and large-scale deployment are often hindered by people's concerns about the security, user privacy, or both. In this dissertation, we aim to address a number of challenging security and privacy issues in heterogeneous wireless and mobile networks in an attempt to foster their widespread adoption. Our contributions are mainly fivefold. First, we introduce a novel secure and loss-resilient code dissemination scheme for wireless sensor networks deployed in hostile and harsh environments. Second, we devise a novel scheme to enable mobile users to detect any inauthentic or unsound location-based top-k query result returned by an untrusted location-based service providers. Third, we develop a novel verifiable privacy-preserving aggregation scheme for people-centric mobile sensing systems. Fourth, we present a suite of privacy-preserving profile matching protocols for proximity-based mobile social networking, which can support a wide range of matching metrics with different privacy levels. Last, we present a secure combination scheme for crowdsourcing-based cooperative spectrum sensing systems that can enable robust primary user detection even when malicious cognitive radio users constitute the majority.
Dissertation/Thesis
Ph.D. Electrical Engineering 2013

Indiana University-Purdue University Indianapolis (IUPUI)
Our ability to engineer materials is limited by our capacity to tailor the material’s microstructure morphology and predict resulting properties. The insufficient knowledge on microstructure-property relationship is due to complexity and randomness in all materials at different scales. The objective of this research is to establish a design optimization methodology for microstructured materials. The material design problem is stated as finding the optimum microstructure to maximize the desired performance satisfying material processing constrains. This problem has been solved in this thesis by means of numerical techniques through four main steps: microstructure characterization, model reconstruction, property evaluation, and optimization. Two methods of microstructure characterizations have been investigated along with the advantages and disadvantages of each method. The first microstructure characterization method is a statistical method which utilizes correlation functions to extract the microstructural information. Algorithms for calculating these correlations functions have been developed and optimized based on their computational cost using MATLAB software. The second microstructure characterization method is physical characterization which works based on evaluation of physical features in microstructured domain. These features have been measured by means of MATLAB codes. Three model reconstruction techniques are proposed based on these characterization methods and employed to generate material models for further evaluation. The first reconstructing algorithm uses statistical functions to reconstruct the statistical equivalent model through simulating annealing optimization method. The second algorithm uses cellular automaton concepts to simulate the grain growth utilizing physical descriptors, and the third one generates elliptical inclusions in a material matrix using physical characteristic of microstructure. The finite element method is used to analysis the mechanical behavior of material models. Several material samples with different microstructural characteristics have been generated to model the micro-scale design domain of AZ31 magnesium alloy and magnesium matrix composite with silicon carbide fibers. Then, surrogate models have been created based on these samples to approximate the entire design domain and demonstrate the sensitivity of the desired mechanical property to two independent microstructural features. Finally, the optimum microstructure characteristics of material samples for fracture strength maximization have been obtained.

Over the past several decades our understanding and meticulous characterization of the transient and spatial properties of materials evolved rapidly. The results present an exciting field for discovery, and craft materials to control and reshape light that we are just beginning to fathom. State-of-the-art nano-deposition processes, for example, can be utilized to build stratified waveguides made of thin dielectric layers, which put together result in a material with effective abnormal dispersion. Moreover, materials once deemed well known are revealing astonishing properties, v.gr. chalcogenide glasses undergo an atomic reconfiguration when illuminated with electrons or photons, this ensues in a temporal modification of its permittivity and permeability which could be used to build new Photonic Integrated Circuits.. This work revolves around the characterization and model of heterogeneous and time-varying materials and their applications, revisits Maxwell's equations in the context of nonlinear space- and time-varying media, and based on it introduces a numerical scheme that can be used to model waves in this kind of media. Finally some interesting applications for light confinement and beam transformations are shown.