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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Range-Based Graph Clustering

Luo, Yongfeng 11 March 2002 (has links)
No description available.
2

BRNĚNSKÉ PODZEMÍ – POTENCIÁL PRO VEŘEJNÝ PROSTOR MĚSTA / BRNO UNDERGROUND - THE POTENTIAL FOR PUBLIC SPACES CITY

Kopáčiková, Zuzana January 2014 (has links)
The subject of the thesis is a transformation of the anti-nuclear shelter situated in the city center, which no longer fulfils its original function. The main goal of the project is to integrate the shelter to surrounding public spaces. The proposal uses the potential of the suitable location on the edge of the historical center of Brno by inclusion of public facilities with cultural functions that are able to use the uniqueness of the underground space. The aim of the study is to point out this unused building, initiate discussion. My quest is to bring new impulse to the city, to enhance the site with a new feature, make a pleasant urban space to residents of the city and also bring life to the place.
3

Intensification of Biological Nutrient Removal Processes

Klaus, Stephanie Anne 29 October 2019 (has links)
Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. At the beginning of this study, granular sidestream deammonification was becoming well-established in Europe, but there was virtually no experience with startup or operation of these processes in North America. The experience gained from optimization of the sidestream deammonification moving bed biofilm reactor (MBBR) in this study, including the novel pH-based aeration control strategy, has influenced the startup procedure and operation of subsequent full-scale installations in the United States and around the world. Long startup time remains a barrier to the implementation of sidestream deammonification processes, but this study was the first to show the benefits of utilizing media with an existing nitrifying biofilm to speed up anammox bacteria colonization. Utilizing media with an established biofilm from a mature integrated fixed film activated sludge (IFAS) process resulted in at least five times greater anammox activity rates in one month than virgin media without a preliminary biofilm. This concept has not been testing yet in a full-scale startup, but has the potential to drastically reduce startup time. False dissolved oxygen readings were observed in batch scale denitrification tests, and it was determined that nitric oxide was interfering with optical DO sensors, a problem of which the sensor manufacturers were not aware. This led to at least one sensor manufacturer reevaluating their sensor design and several laboratories and full-scale process installations were able to understand their observed false DO readings. There is an industry-wide trend to utilize influent carbon more efficiently and realize the benefits of mainstream shortcut nitrogen removal. The A/B pilot at the HRSD Chesapeake Elizabeth Treatment provides a unique chance to study these strategies in a continuous flow system with real wastewater. For the first time, it was demonstrated that the presence of influent particulate COD can lead to higher competition for nitrite by heterotrophic denitrifying bacteria, resulting in nitrite oxidizing bacteria (NOB) out-selection. TIN removal was affected by both the type and amount of influent COD, with particulate COD (pCOD) having a stronger influence than soluble COD (sCOD). Based on these findings, an innovative approach to achieving energy efficient biological nitrogen removal was suggested, in which influent carbon fractions are tailored to control specific ammonia and nitrite oxidation rates and thereby achieve energy efficiency in the nitrogen removal goals downstream. Intermittent and continuous aeration strategies were explored for more conventional BNR processes. The effect of influent carbon fractionation on TIN removal was again considered, this time in the context of simultaneous nitrification/denitrification during continuous aeration. It was concluded that intermittent aeration was able to achieve equal or higher TIN removal than continuous aeration at shorter SRTs, whether or not the goal is nitrite shunt. It is sometimes assumed that converting to continuous aeration ammonia-based aeration control (ABAC) or ammonia vs. NOx (AvN) control will result in an additional nitrogen removal simply by reducing the DO setpoint resulting in simultaneous nitrification/denitrification (SND). This work demonstrated that lower DO did not always improve TIN removal and most importantly that aeration control alone cannot guarantee SND. It was concluded that although lower DO is necessary to achieve SND, there also needs to be sufficient carbon available for denitrification. While the implementation of full-scale sidestream anammox happened rather quickly, the implementation of anammox in the mainstream has not followed, without any known full-scale implementations. This is almost certainly because maintaining reliable mainstream NOB out-selection seems to be an insurmountable obstacle to full-scale implementation. Partial denitrification/anammox was proven to be easier to maintain than partial nitritation/anammox and still provides significant aeration and carbon savings compared to traditional nitrification/denitrification. There is a long-standing interest in combining shortcut nitrogen removal with biological phosphorus removal, without much success. In this study, biological phosphorus removal was achieved in an A/B process with A-stage WAS fermentation and shortcut nitrogen removal in B-stage via partial denitrification. / Doctor of Philosophy / When the activated sludge process was first implemented at the beginning of the 20th century, the goal was mainly oxygen demand reduction. In the past few decades, treatment goals have expanded to include nutrient (nitrogen and phosphorus) removal, in response to regulations protecting receiving bodies of water. The only practical way to remove nitrogen in municipal wastewater is via biological treatment, utilizing bacteria, and sometimes archaea, to convert the influent ammonium to dinitrogen gas. Orthophosphate on the other hand can either be removed via chemical precipitation using metal salts or by conversion to and storage of polyphosphate by polyphosphate accumulating organisms (PAO) and then removed in the waste sludge. Nitrification/denitrification and chemical phosphorus removal are well-established practices but utilize more resources than processes without nutrient removal in the form of chemical addition (alkalinity for nitrification, external carbon for denitrification, and metal salts for chemical phosphorus removal), increased reactor volume, and increased aeration energy. Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. Partial nitritation/anammox is a relatively new technology that has been implemented in many full-scale sidestream processes with high ammonia concentrations, but that has proven difficult in more dilute mainstream conditions due to the difficulty in suppressing nitrite oxidizing bacteria (NOB). Even more challenging is integrating biological phosphorus removal with shortcut nitrogen removal, because biological phosphorus removal requires the readily biodegradable carbon that is diverted. Partial denitrification/anammox provides a viable alternation to partial nitritation/anammox, which may be better suited for integration with biological phosphorus removal.
4

Adiabatisk genväg till quditberäkning / Adiabatic shortcut to holonomic qudit computation

Smith, Kellen January 2021 (has links)
One of the major challenges hindering advancement of quantum computing is the sensitive nature of the physical systems used to build a quantum computer. One suggestion for improving reliability is a particular type of logic gates, based on Berry's geometric phase, showing improved robustness to external disturbance of the quantum system over the course of a calculation. Such logic gates have previously been shown for the smallest possible two-level qubits. Using the method of adiabatic shortcut we endevour to discover similarly realistic and robust logic gates for units of quantum information in higher dimensions. The example shown in this paper discusses three-level qutrits, but is expected to apply to theoretically unlimited higher dimensions since new geometric complications are expected to arise primarily when moving from a two-level to a multi-level problem.  We here present a set of primitive single-qutrit gates able to perform universal quantum computations if supplemented by a two-qutrit gate. We also present a set of condensed single-qutrit gates for commonly needed operations. By detailing the underlying mathematical framework, relying on the multi-dimensional generalisation of Berry's phase describing the time evolution of degenerate quantum states, we also suggest an easily scalable geometric interpretation of quantum gates in higher dimensions along with visual representation of logic gates using parameters of the physical system to sequentially unlock and manipulate subspaces of the quantum information unit.
5

Charged systems in, out of, and driven to equilibrium : from nanocapacitors to cement / Systèmes chargés à l'équilibre, hors d'équilibre et pilotés : des nanocondensateurs au ciment

Palaia, Ivan 15 November 2019 (has links)
La plupart des systèmes en matière molle sont en contact avec des solutions contenant des espèces chargées. Certains d’entre eux sont bien décrits par des théories de champ moyen, d’autres nécessitent des approches plus fines qui tiennent compte des corrélations entre ions.Dans la première partie de cette thèse, nous analysons la dynamique de relaxation d’un nanocondensateur. Les techniques analytiques et numériques utilisées relèvent du champ moyen (formalisme de Poisson-Nernst-Planck). Nous étudions les temps caractéristiques de relaxation dans les régimes linéaire et non linéaire et caractérisons le comportement du système en fonction de la concentration en sel et du potentiel appliqué. Les géométries planaire et coaxiale sont traitées. Nous nous intéressons ensuite au problème de concevoir un protocole temporel pour le potentiel appliqué, capable de piloter le système d’un état d’équilibre à un autre, que ce soit pour accélérer le processus de formation de la double couche électrique ou celui d’instauration d’un flux électroosmotique.Dans la deuxième partie, nous abordons la physique des systèmes chargés corrélés, avec une attention particulière pour le phénomène d’attraction entre charges du même signe. Nous élaborons une théorie qui décrit les systèmes sans sel à l’équilibre, quelle que soit la valeur du paramètre de couplage électrostatique. Inspirée en partie par le concept du trou de corrélation et en partie par un formalisme à la Poisson-Boltzmann, la théorie satisfait nombre de résultats exacts et elle peut être facilement résolue numériquement.Dans la troisième partie, nous développons la théorie du couplage fort pour les constituants nanoscopiques du ciment. Après avoir présenté l’histoire et l’état de l’art dans notre compréhension de la physique de cet omniprésent matériau, nous analysons des simulations de dynamique moléculaire de l’interface entre plaquettes de C-S-H. Nous montrons que la grande force de cohésion observée est due à une baisse de la permittivité diélectrique sous confinement, ce qui augmente l’importance des corrélations. Nous étudions la statistique du phénomène d’hydratation des ions, et finalement obtenons de façon analytique la pression en fonction de la distance entre plaquettes, en excellent accord avec les simulations. / Most systems in soft matter are immersed in solutions with charged species. Some of them can be described by mean-field techniques, while others require more sophisticated treatments that account for correlations between ions.In the first part of this thesis, we analyze the relaxation dynamics of a nanocapacitor. We use analytical and numerical techniques within mean-field (so-called Poisson-Nernst-Planck formalism). We study characteristic relaxation times in the linear and nonlinear regime and characterize the behavior of the system as a function of salt density and applied voltage. Both the parallel plate and the coaxial geometries are examined. The problem of designing a smart time-dependent applied potential, to drive the system from an initial to a final equilibrium state is also tackled, with regard to both the electric double layer build-up process and the establishment of an electroosmotic flow.In the second part, the physics of correlated charged systems is presented, with particular focus on the like-charge attraction phenomenon. We develop a theory describing salt-free systems, at arbitrary value of the electrostatic coupling parameter. Inspired partly by the correlation-hole concept and partly by the Poisson-Boltzmann formalism, the theory satisfies a number of exact requirements and can be easily solved numerically.In the third part, we develop the theory of strong coupling for the nanoscopic constituents of set cement. After introducing the history and the present understanding of the physics behind this omnipresent material, we analyze molecular dynamics simulations of the interface between C-S-H platelets (Calcium Silicate Hydrate). We show that the strong cohesion force observed is ultimately due to a decrease in the dielectric permittivity under confinement, which enhances correlations. We study the statistics of ion hydration and obtain analytically the pressure as a function of inter-platelet distance, in excellent agreement with simulations.
6

Adiabatic Shortcut to Geometric Quantum Computation in Noiseless Subsystems

Gregefalk, Anton January 2021 (has links)
Quantum computers can theoretically perform certain tasks which classical computers at realistic times could not. Operating a quantum computer requires precise control over the system, for instance achieved by adiabatic evolution, and isolation from the environment to retain coherence. This report combines these two, somewhat contradicting, error preventing techniques. To reduce the run-time a transitionless quantum driving algorithm, or, adiabatic shortcut, is employed. The notion of Noiseless Subsystems (NS), a generalization of decoherence free subspaces, are used for robustness against environmental decoupling, by creating logical qubits which act as a noiseless code. Furthermore, the adiabatic shortcut for the NS code is applied to a refocusing scheme (spin-echo) in order to remove the dynamical phase, sensitive to error propagation, so that only the Berry phase is effectively picked up. The corresponding Hamiltonian is explicitly derived for the only two cases of two-dimensional NS: N=3,4 qubits with total spin of j=1/2,0, respectively. This constitutes geometric quantum computation (GQC) enacting a universal single-qubit gate, which is also explicitly derived. / Kvantdatorer kan teoretiskt utföra vissa uppgifter som klassiska datorer vid realistiska tider inte kan. Att köra en kvantdator kräver exakt kontroll över systemet, till exempel genom adiabatisk utvecking, och isolering från omgiviningen för att behålla koherens. Denna rapport kombinerar dessa två, något motsägelsefulla, tekniker för felhantering. För att minska körtiden används en övergångsfri kvantkörningsalgoritm, också kallad adiabatisk genväg. Konceptet brusfria delsystem, en generalisering av dekoherensfria underrum, används för robusthet mot sammanflätning med omgivningen genom att skapa logiska kvantbitar som fungerar som en brusfri kod. Vidare tillämpas den adiabatiska genvägen för den brusfria koden på ett spinn-eko för att eliminera den dynamiska fasen, som är känslig för felpropagering, så att endast Berrys fas, som är okänslig för felpropagering, effektivt plockas upp. Motsvarande Hamiltonian härleds uttryckligen för de enda två fallen av tvådimensionella brusfria delsystem: 3 eller 4 kvantbitar med respektive totalspinn j = 1/2 och 0. Detta möjliggör beräkning med en geometrisk kvantdator baserad på en universell en-kvantbitsgrind, som också härleds explicit.
7

工程中受害補償制度之研究--以台北市大眾捷運系統為例

曾育裕, ZENG, YU-YU Unknown Date (has links)
研究目的﹕台北市議會於民國七十六年七月十日通過大眾捷運系統第一期工程特別預 算時,曾附帶但一要求在工程施工期間,對沿線住戶如因此受害時,應給予工程受害 補償費,並酌情減免營業稅、房屋稅及地價稅。此決議顧及特別犧牲民眾之權益,可 謂極其明智,值得喝彩!但中央法規標準法第五條規定﹕「關係人民權利、義務之事 項,應以法律定之。」故在缺乏一套完整之工程規模龐大的大眾捷運系統,因其施工 所造成人民權益之損害,在補償救濟上,建立一套可行的法律依據及其法律理論基礎 。〞受益付費,受害補償〞為一基本之法律理念,然我國現行法僅有〞受益付費〞之 「工程受益費微收條例」,卻無〞受害補償〞之法制,本論文藉此研究,對此一工程 中受害補償法制,提倛一解決方向,此本論文之另一目的也。 文獻﹕參考中興大學都市計劃研究所研究之「台北地區大眾捷運工程受害與受益之研 究」;中鼎顧問公司研究之「台北地區大眾捷運系統環境影響評估報告」;交通大學 運輸研究所研究之「台北市中運旺捷運系統環境評估」等做為主要之文獻回顧,以對 捷運工程之施工影響有所認識,再據此作為本論文研究之開展。主要之研究文獻,因 國內缺乏,故多引用日本、新加坡、香港、德國等之資料。 研究方法﹕本研究著重於法制之探討,以現行法制所無者,對新法制之可採,為實現 、改革之鼓吹;故研究方法著重於法理的週詳建立,外國相關法制之比較研究,以求 其同、觀其異、採其長、捨其短。主要研究方法比較研究法及理論探討法兩種。 研究內容﹕本論文之研究內容除文獻回顧外,再就新加坡、香港、德國之立法例予以 比較研究;並從憲法理論、國家責任理論、損失補償理論深入探討本研究之理論基礎 ;最後得出工程中受害補償法制之輪廓及可行方向,以結論及建議終結本論本。 研究結果﹕無論從法學理論或外國法例,甚至從公平正義之觀點視之,我國均有必要 建立工程中受害補償之制度;短期作法,可將之列入「大眾捷運法」中,以求對此一 鉅大工程所帶來之侵害影響,有一解決之道;長期作法,則應另行建立一套完整的「 工程中受害補償法」,以期政府部門因興建公共工程,對人民造成損害結果時,有一 妥適完善之解決制度。
8

台北市地價變遷與空間分佈影響因素之研究

李育坤, LI, YU-KUN Unknown Date (has links)
研究目的 瞭解台北市地價變遷及空間分佈情形、影響因素,並測定捷運系統完成將對地價產何 種變動,以供制定地價政策、都市規劃之參考。 研究文獻 本文擷取下列三種研究方向之國、內外地價理論、實證文獻作為參考﹕(一)都市地 價之形成與形成因素之相關計量分析。(二)都市內部各地地價差異影響因素之研究 。(三)運輸改善對地價影響之研究。 研究方法 由相關文獻之參考,提出對地價之變遷及空間分佈較大影響之因素,以計量方法由此 等影響因素對地價之關係建立地價變遷、空間結構模式,以測定各項因素之影響力。 分析方法採統計分析,計有次數分配、相關分析、時間序列分析及迴歸分析等,藉電 腦處理資料來進行。 研究內容 本文計分五章,第一章緒論,說明本文研究動機,目的、方法、步驟及相關文獻回顧 。第二章為台北地價變遷之探討,藉地價指數之編製,瞭解其變遷情形及建立整體地 價變動模型,瞭解各因素之影響力。第三章為台北市地價空間分佈探討,以負指數模 型來測定距離與地價之關係,並建立內部各地地價差異之影響因素模型。第四章為捷 運系統完成對地價影響之研究,以實際資料建立一運輸改善模型以測定地價將產生何 種變動。第五章為結論與建議。 研究結果 (一)台北市地價變遷迅速,地價政策應慎重制定。 (二)地價空間分佈差異,除距離、人口因素外,土地使用強度之編定一大決定因素 ,故都市規劃之制定應考慮其地價因素。 (三)運輸改善對地價將產生變動,沿線地區(尤其車站附近)之上漲迅速,對其灴 良影響(如土地投機)應儘早制定相關政策控制。
9

Étude des référentiels de géométrie utilisés en classe de mathématiques au secondaire

Cyr, Sébastien 01 1900 (has links)
Durant leur parcours au secondaire (12 à 17 ans), les élèves sont amenés à résoudre des problèmes de preuves en classe de mathématiques (MELS, 2006a, 2006b). En géométrie, ces preuves doivent s’appuyer sur un référentiel théorique composé de propriétés et de définitions (Kuzniak et Richard, 2014). Afin de dégager les particularités des référentiels utilisés en classe, nous avons relevé et analysé les propriétés et les définitions de dix-neuf ouvrages scolaires québécois de 1re secondaire à la 5e secondaire. Chacun des éléments ainsi relevés a été identifié selon les concepts sous-tendus dans leurs énoncés, leurs valeurs épistémiques possibles, leur dépendance à une figure et leur place au sein du chapitre. Cette étude se base sur le concept des paradigmes géométriques (Houdement et Kuzniak, 2006) et le modèle des Espaces de Travail Mathématique (ETM) (Kuzniak et Richard, 2014) où le référentiel fait partie de la genèse discursive engendrée par un travail mathématique. L’étude des référentiels montre que plusieurs modalités discursives dans leur enseignement peuvent générer des difficultés lorsque vient le temps de les utiliser dans une preuve. Cette étude confirme aussi l’oscillation entre les paradigmes géométriques (Gauthier, 2015; Tanguay et Geeraerts, 2012) dans l’enseignement de la géométrie. Enfin, nous proposons un référentiel possible pour un agent tuteur d’aide à la démonstration selon le curriculum québécois. / During their high school career (12 to 17 years old), students are required to solve proof-based problems in their mathematics classes (MELS, 2006a, 2006b). In geometry, these mathemactical proofs must be supported by a theoretical referential of properties and definitions (Kuzniak et Richard, 2014). To determine the specifics of the referentials used in classes, we noted and analyzed the properties and definitions of nineteen Quebec secondary school textbooks. Each item was identified according to the concepts underlying in their statements, their possible epistemic value, their reliance on a figure, and their placement in the chapter. This study is based on the concept of geometric paradigms (Houdement et Kuzniak, 2006) and on the Mathematical Working Space model (MWS or ETM in French) (Kuzniak et Richard, 2014) where the referential is part of the discursive genesis generated by a mathematical work. This study on referentials demonstrates that there are many discursive modalities used in teaching, which can produce difficulties when they are required to be used in a proof. This study also confirms the oscillation between the geometric paradigms (Gauthier, 2015; Tanguay et Geeraerts, 2012) when teaching geometry. Furthermore, we propose a possible referential to be used in a demonstration aid tutor in accordance with Quebec’s curriculum.
10

Engineered atomic states for precision interferometry / Ingénierie d’états atomiques pour l’interférométrie de précision

Corgier, Robin 02 July 2019 (has links)
La physique moderne repose sur deux théories fondamentales distinctes, la relativité générale et la mécanique quantique. Toutes les deux décrivent d’une part les phénomènes macroscopiques et cosmologiques tels que les ondes gravitationnelles et les trous noirs et d’autre part les phénomènes microscopiques comme la superfluidité ou le spin des particules. L’unification de ces deux théories reste, jusqu’à présent, un problème non résolu. Il est intéressant de noter que les différentes théories de gravité quantique prédisent une violation des principes de la relativité générale à différents niveaux.Il est donc hautement intéressant de détecter les violations de ces principes et de déterminer à quel niveau elles se produisent.De récentes propositions pour effectuer des tests du principe d’ équivalence d’Einstein suggèrent une amélioration spectaculaire des performances en utilisant des capteurs atomiques `a ondes de matière.Dans ce contexte, il est nécessaire de concevoir des états d’entrée de l’interferomètre avec des conditions initiales bien définies. Un test de pointe de l’universalité de la chute libre (Universality of FreeFall en anglais (UFF) ) nécessiterait, par exemple,un contrôle des positions et des vitesses avec une précision de l’ordre de 1 μm et 1 μm.s⁻¹ , respectivement.De plus, les systématiques liées à la taille du paquet d’ondes limitent le taux d’expansion maximum possible à 100 μm.s⁻¹. La création initiale des états d’entrée de l’interféromètre doit être assez rapide,de l’ordre de quelques centaines de ms au maximum,pour que le temps de cycle de l’expérience soit pertinent d’un point de vue métrologique. Dans cette thèse j’ai développé des séquences optimisées s’appuyant sur l’excitation du centre de masse et de la taille d’un ou plusieurs ensembles d’atomes refroidis ainsi que dégénérés. Certaines séquences proposé dans cette thèse ont déjà été implémenté dans des expériences augmentant de manière significative le contrôle des ensembles atomiques. / Modern physics relies on two distinct fundamental theories, General Relativity and Quantum Mechanics. Both describe on one hand macroscopic and cosmological phenomena such as gravitational waves and black holes and on the other hand microscopic phenomena as superfluidity or the spin of particles. The unification of these two theories remains, so far, an unsolved problem. Interestingly, candidate Quantum Gravity theories predict a violation of the principles of General Relativity at different levels. It is, therefore, of a timely interest to detect violations of these principles and determine at which level they occur. Recent proposals to perform Einstein Equivalence Principle tests suggest a dramatic performance improvement using matter-wave atomic sensors. In this context, the design of the input states with well defined initial conditions is required. A state-of-the-art test of the universality of free fall (UFF) would, for example, require a control of positions and velocities at the level of 1 µm and 1 µm.s⁻¹, respectively. Moreover, sizerelated systematics constrain the maximum expansion rate possible to the 100 µm.s⁻¹level. This initial engineering of the input states has to be quite fast, of the order of few hundred ms at maximum, for the experiment’s duty cycle to be metrologically-relevant. In this thesis I developed optimized sequences based on the excitation of the center of mass and the size excitation of one or two cooled atomic sample as well as degenerated gases. Some sequences proposed in this thesis have already been implemented in experiments and significantly increase the control of atomic ensembles.

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