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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.
71

Monitoramento e avaliação de sistema de tratamento para águas negras composto por reator UASB, fotobiorreator, flotação e processos de desinfecção / Monitoring and evaluation of treatment system for wastewater composed of UASB reactor, photobioreactor, flotation and disinfection processes

Slompo, Nathalie Dyane Miranda 02 July 2018 (has links)
O modelo econômico extrair, transformar, descartar da atualidade está atingindo seus limites físicos. Confrontando-se com questões de disponibilidade de recursos A economia circular é uma alternativa atraente que busca redefinir a noção de crescimento, com foco em benefícios para toda a sociedade. Dentro dessa nova visão, conceitos de tratamentos descentralizados e sustentáveis de saneamento que concentram-se no tratamento e na reciclagem dos recursos presentes nas águas residuais domésticas são considerados. Assim, a partir de uma água residuária é possível obter três recursos principais: a bioenergia, nutrientes e água. Esta pesquisa teve por objetivo principal avaliar a produção de um efluente propício ao reúso não potável, a partir de água negra. A água negra foi tratada anaerobiamente (reator UASB) para remoção de matéria orgânica, seguindo para um fotobiorreator para remoção de nutrientes, com consequente separação da biomassa algal por flotação por ar dissolvido. Neste ponto foi avaliada a absorção de nutrientes pelas microalgas e o crescimento de sua biomassa. Após a flotação, o efluente foi desinfetado, avaliada assim, a inativação de coliformes totais e Escherichia coli, bem como de Giardia spp. e Cryptosporidium spp. no sistema de tratamento. O reator UASB manteve níveis elevados de remoção de matéria orgânica (DQO), com remoções de 70%. Apresentando uma média de remoção de Escherichia coli e coliformes fecais entre 1 e 3 log. Para protozoários essa remoção foi entre 0,5 e 1,5 log. O fotobiorreator, obteve satisfatório crescimento da biomassa, sem controle de temperaturas ou suplementação de CO2, apresentou também remoção/inativação de Escherichia coli e coliformes totais, com valores entre 0,50 a quase 3,0 log, apresentando de modo geral maior remoção/inativação para Escherichia coli. Foi observado remoção de protozoários e coliformes pela flotação por ar dissolvido, acarretando uma maior concentração destes na biomassa removida. O melhor desinfetante individual foi o cloro, em razão da inativação. No entanto, o ozônio foi o que melhor obteve remoção (oxidação) de matéria orgânica. Em relação aos desinfetantes aplicados de modo sequencial ou simultâneos, foi observado que a melhor inativação foi promovida pelo ensaio sequencial com ozônio e cloro, com inativação de até 3,10 e 3,38 log para Escherichia coli e coliformes totais, respectivamente. Com efeito sinérgico em relação a aplicação individual destes desinfetantes. Recomenda-se o uso do sistema para o tratamento descentralizado, principalmente em pequenas comunidades e em áreas rurais. / The current economic \"extract, transform, discard\" model is reaching its physical limits. Confronting with issues of resource availability Circular economics is an attractive alternative that seeks to redefine the notion of growth, with a focus on benefits for the whole society. Within this new vision, concepts of decentralized and sustainable sanitation treatments that focus on the treatment and recycling of resources present in domestic wastewater are considered. Thus, from a wastewater it is possible to obtain three main resources: bioenergy, nutrients and water. The main objective of this research was to evaluate the production of an effluent conducive to non-potable reuse from black water. The black water was treated anaerobically (UASB reactor) to remove organic matter, followed by a photobioreactor to remove nutrients, with consequent separation of the algal biomass by dissolved air flotation. At this point, the nutrient uptake by microalgae and the growth of their biomass were evaluated. After flotation, the effluent was disinfected, thus evaluating the inactivation of total coliforms and Escherichia coli, as well as Giardia spp. and Cryptosporidium spp. in the treatment system. The UASB reactor maintained high levels of organic matter removal (COD), with removals of 70%. Presents an average removal of Escherichia coli and faecal coliforms between 1 and 3 log. For protozoa this removal was between 0.5 and 1.5 log. The photobioreactor, obtained satisfactory biomass growth, without temperature control or CO2 supplementation, also showed removal/inactivation of Escherichia coli and total coliforms, with values ranging from 0.50 to almost 3.0 log, generally presenting greater removal inactivation for Escherichia coli. Removal of protozoa and coliforms by flotation by dissolved air was observed, leading to a higher concentration of these in the biomass removed. The best individual disinfectant was chlorine, due to inactivation. However, ozone was the one that best obtained removal (oxidation) of organic matter. Regarding disinfectants applied sequentially or simultaneously, it was observed that the best inactivation was promoted by the sequential test with ozone and chlorine, with inactivation of up to 3.10 and 3.38 log for Escherichia coli and total coliforms, respectively. With synergistic effect in relation to the individual application of these disinfectants. It is recommended to use the system for decentralized treatment, especially in small communities and in rural areas.
72

Les relations et les actions bilatérales des communes françaises 1884-2014. : Pour une conceptualisation et une étude du bilatéralisme communal / The french municipalities bilateral relations and actions, 1884-2014.

Balducci, Christelle 27 October 2017 (has links)
De nombreuses communes françaises sont aujourd’hui ouvertes sur l’extérieur et engagées dans des relations avec d’autres localités françaises ou étrangères : les panneaux aux entrées des villes, les articles dans la presse locale et régionale, les pages sur les sites Internet, les divers documents conservés dans les archives municipales en témoignent. Les jumelages et les coopérations nous sont familiers et développer des relations et des actions bilatérales est une pratique municipale aujourd’hui habituelle.Partant de ce constat cette thèse propose d’en tracer l’histoire depuis la loi municipale de 1884 jusqu’en 2014 et de tenter de construire le concept de « bilatéralisme communal ». Par définition, le « bilatéralisme » correspond au sens strict à une politique d’accords, d’échanges entre des Etats pris deux à deux et ce terme n’a, semble-t-il, jamais été associé aux communes. Pourtant, cette expression « bilatéralisme communal » nous paraît pertinente pour désigner une pratique municipale courante.Afin de comprendre comment se sont développés et fonctionnent les rapports nationaux et transnationaux au niveau le plus simple et d’expliquer l’engagement des communes françaises dans des relations et des actions bilatérales, cette étude se décompose en trois axes complémentaires : le premier s’applique à expliquer les contextes dans lesquels les relations bilatérales s’inscrivent, le deuxième s’intéresse à la mise en place de la relation bilatérale, enfin le troisième a trait aux rapports entre les villes et entend porter un regard critique sur le bilatéralisme communal.L’histoire des relations et des actions bilatérales des communes françaises nous amène donc à nous intéresser aux rapprochements et aux échanges au niveau administratif le plus bas et nous conduit au cœur d’une forme élémentaire du jeu diplomatique aux origines relativement anciennes. / Many French municipalities are now open to the outside world and engaged in relations with other French or foreign localities : signs at the entrances to cities, articles in the local and regional press, pages on Internet sites, the various documents kept in the municipal archives testify to this. Twinning and cooperation are familiar to us and developing bilateral relations and actions is a usual municipal practice today.On the basis of this observation, this thesis proposes to trace its history from the municipal law of 1884 until 2014 and to attempt to construct the concept of "communal bilateralism". By definition, "bilateralism" corresponds in the strict sense to a policy of agreements, exchanges between States taken two by two, and this term has never been associated with municipalities. Yet this expression "communal bilateralism" seems to us to be relevant to common municipal practice.In order to understand how national and transnational reports have developed and function at the simplest level and to explain the involvement of French municipalities in bilateral relations and actions, this study is divided into three complementary axes : the first applies to explain the contexts in which bilateral relations take place, the second focuses on the establishment of the bilateral relationship, and finally the third deals with the relations between cities and intends to take a critical look at communal bilateralism.The history of the bilateral relations and actions of the French municipalities therefore leads us to focus on rapprochement and exchanges at the lowest administrative level and leads us to the heart of an elementary form of the diplomatic game with relatively old origins.
73

Decentralized control of multi-agent aerial transportation system

Toumi, Noureddine 04 1900 (has links)
Autonomous aerial transportation has multiple potential applications including emergency cases and rescue missions where ground intervention may be difficult. In this context, the following work will address the control of multi-agent Vertical Take-off and Landing aircraft (VTOL) transportation system. We develop a decentralized method. The advantage of such a solution is that it can provide better maneuverability and lifting capabilities compared to existing systems. First, we consider a cooperative group of VTOLs transporting one payload. The main idea is that each agent perceive the interaction with other agents as a disturbance while assuming a negotiated motion model and imposing certain magnitude bounds on each agent. The theoretical model will be then validated using a numerical simulation illustrating the interesting features of the presented control method. Results show that under specified disturbances, the algorithm is able to guarantee the tracking with a minimal error. We describe a toolbox that has been developed for this purpose. Then, a system of multiple VTOLs lifting payloads will be studied. The algorithm assures that the VTOLs are coordinated with minimal communication. Additionally, a novel gripper design for ferrous objects is presented that enables the transportation of ferrous objects without a cable. Finally, we discuss potential connections to human in the loop transportation systems.
74

The coordinated control of autonomous agents

Abel, Ryan Orlin 01 December 2010 (has links)
This thesis considers the coordinated control of autonomous agents. The agents are modeled as double integrators, one for each Cartesian dimension. The goal is to force the agents to converge to a formation specified by their desired relative positions. To this end a pair of one-step-ahead optimization based control laws are developed. The control algorithms produce a communication topology that mirrors the geometric formation topology due to the careful choice of the minimized cost functions. Through this equivalence a natural understanding of the relationship between the geometric formation topology and the communication infrastructure is gained. It is shown that the control laws are stable and guarantee convergence for all viable formation topologies. Additionally, velocity constraints can be added to allow the formation to follow fixed or arbitrary time dependent velocities. Both control algorithms only require local information exchange. As additional agents attach to the formation, only those agents that share position constraints with the joining agents need to adjust their control laws. When redundancy is incorporated into the formation topology, it is possible for the system to survive loss of agents or communication channels. In the event that an agent drops out of the formation, only the agents with position interdependence on the lost agent need to adjust their control laws. Finally, if a communication channel is lost, only the agents that share that communication channel must adjust their control laws. The first control law falls into the category of distributed control, since it requires either the global information exchange to compute the formation size or an a priori knowledge of the largest possible formation. The algorithm uses the network size to penalize the control input for each formation. When using a priori knowledge, it is shown that additional redundancy not only adds robustness to loss of agents or communication channels, but it also decreases the settling times to the desired formation. Conversely, the overall control strategy suffers from sluggish response when the network is small with respect to the largest possible network. If global information exchange is used, scalability suffers. The second control law was developed to address the negative aspects of the first. It is a fully decentralized controller, as it does not require global information exchange or any a priori knowledge.
75

Wastewater Nutrient Recovery Using Anaerobic Membrane Bioreactor Permeate for Hydroponic Fertigation

Calabria, Jorge Luis 30 October 2014 (has links)
The imbalance between global population growth and resource consumption is indicative of unsustainable practices and foreshadows a grim future of continued resource depletion, food and water scarcity, social inequality, and deteriorating public and environmental health. Meanwhile, the urban centers of the world continue to experience exponential growth resulting in overwhelmed food, water, and sanitation infrastructure. Decentralized and satellite wastewater treatment technologies capable of resource recovery, such as anaerobic membrane bioreactors (AnMBR), foster synergistic opportunities to help manage the food, energy, and water sectors of urban environments. Specifically, the nutrient concentration and high effluent quality of permeate produced by AnMBR systems present applicability in controlled environment agriculture (CEA). The efficacy of AnMBR permeate is evaluated in a hydroponics growth study of cucumber (Cucumis sativus) grown in an outdoor greenhouse and tomato (Lycopersicon lycopersicum) grown indoors. Nutrient analysis of permeate generated by a small, pilot scale AnMBR developed for the treatment of domestic wastewater at ambient temperature indicated sufficient concentrations of N and P elements, however high proportion of NH4+ in N species decreased growth performance. Opportunities for optimizing AnMBR permeate for hydroponics applications exist and thus imply synergistic integration of decentralized AnMBR technology with controlled environment agriculture (CEA) such as hydroponics. A model is proposed for the integration of decentralized AnMBR and CEA systems capable of producing usable plant products within the urban environment. The integration of these systems is proposed as a solution to the challenges of with food security, stressed water supplies, and environmental degradation associated with unchecked urban growth in the developing and developed world
76

Le Partage du Spectre dans les Réseaux Décentralisés Auto-Configurables : Une approche par la Théorie des Jeux.

Perlaza, Samir 08 July 2011 (has links) (PDF)
Les travaux de cette thèse s'inscrivent tous dans la thématique " traitement du signal pour les réseaux de communications distribués ". Le réseau est dit distribué au sens de la décision. Dans ce cadre, le problème générique et important que nous avons approfondi est le suivant. Comment un terminal, qui a accès à plusieurs canaux de communications, doit-il répartir (de manière autonome) sa puissance d'émission entre ses canaux et l'adapter dans le temps en fonction de la variabilité des conditions de communications ? C'est le problème de l'allocation de ressources adaptative et distribuée. Nous avons développé 4 axes de travail qui ont tous conduits à des réponses originales à ce problème ; la forte corrélation entre ces axes est expliquée dans le manuscrit de thèse. Le premier axe a été l'alignement opportuniste d'interférence. Un des scénarios de référence est le cas où deux couples émetteur-récepteur communiquent en interférant (sur la même bande, en même temps, au même endroit, ...), où les 4 terminaux sont équipés de plusieurs antennes et où un émetteur est contraint de ne pas (ou peu) interférer sur l'autre (canal à interférence dit MIMO). Nous avons conçu une technique d'émission de signal multi-antennaire qui exploite l'observation-clé suivante et jamais exploitée auparavant: même lorsqu'un émetteur est égoïste au sens de ses performances individuelles, celui-ci laisse des ressources spatiales (dans le bon espace de signal et que nous avons identifié) vacantes pour l'autre émetteur. L'apport en performances en termes de débit par rapport aux meilleurs algorithmes existants a été quantifié grâce à la théorie des matrices aléatoires et des simulations Monte Carlo. Ces résultats sont particulièrement importants pour le scénario de la radio cognitive en milieu dense. Dans un second temps, nous avons supposé que tous les émetteurs d'un réseau sont libres d'utiliser leurs ressources de manière égoïste. Les ressources sont données ici par les canaux fréquentiels et la métrique individuelle de performance est le débit. Ce problème peut être modélisé par un jeu dont les joueurs sont les émetteurs. Une de nos contributions a été de montrer que ce jeu est un jeu de potentiel, ce qui est fondamental pour la convergence des algorithmes distribués et l'existence d'équilibre de Nash. De plus, nous avons montré l'existence d'un paradoxe de Braess : si l'espace d'optimisation d'un joueur grandit, les performances individuelles et globales peuvent s'en trouver réduites. Cette conclusion a une conséquence pratique immédiate : il peut y a voir intérêt de restreindre le nombre de canaux fréquentiels utilisables dans un réseau à interférence distribué. Dans le jeu précédent, nous avions constaté que les algorithmes distribués d'allocation de ressources (les algorithmes d'apprentissage par renforcement typiquement) demandent un grand nombre d'itérations pour converger vers un état stable tel qu'un équilibre de Nash. Nous avons ainsi proposé un nouveau concept de solution d'un jeu, à savoir l'équilibre de satisfaction ; les joueurs ne modifient pas leur action, même si celle-ci ne maximise pas leur gain, pourvu qu'un niveau minimal de performance soit atteint. Nous avons alors développé une méthodologie d'étude de cette solution (existence, unicité, convergence, ...). Une de nos contributions a aussi été de donner des algorithmes d'apprentissage qui convergent vers cette solution en un temps fini (et même court génériquement). De nombreux résultats numériques réalisés dans des scénarios imposés par Orange ont confirmé la pertinence de cette nouvelle approche. Le quatrième axe de travail a été la conception de nouveaux algorithmes d'apprentissage qui convergent vers des solutions de type équilibre logit, epsilon-équilibre ou équilibre de Nash. Notre apport a été de montrer comment modifier les algorithmes existants pour que ceux-ci évitent les phénomènes de cycles et convergent vers un équilibre présélectionné au départ de la dynamique. Une idée importante a été d'introduire une dynamique d'apprentissage de la fonction métrique de performances en couplage avec la dynamique principale qui régit l'évolution de la distribution de probabilité sur les actions possibles d'un joueur. Le cadre de ces travaux est parfaitement réaliste d'un point de vue informatif au niveau des terminaux en pratique. Il est montré une voie possible pour améliorer l'efficacité des points de convergence, ce qui constitue un problème encore ouvert dans ce domaine.
77

Distributed Monitoring and Resource Management for Large Cloud Environments

Wuhib, Fetahi Zebenigus January 2010 (has links)
Over the last decade, the number, size and complexity of large-scale networked systems has been growing fast, and this trend is expected to accelerate. The best known example of a large-scale networked system is probably the Internet, while large datacenters for cloud services are the most recent ones. In such environments, a key challenge is to develop scalable and adaptive technologies for management functions. This thesis addresses the challenge by engineering several protocols  for distributed monitoring and resource management that are suitable for large-scale networked systems. First, we present G-GAP, a gossip-based protocol we developed for continuous monitoring of aggregates that are computed from device variables. We prove the robustness of this protocol to node failures and validate, through simulations, that its estimation accuracy does not change with increasing size of the monitored system under certain conditions. Second, we present TCA-GAP, a tree-based protocol, and TG-GAP, a gossip-based protocol for the purpose of monitoring threshold crossings of aggregates. For both protocols, we prove correctness properties and show, again through simulations, that both protocols are efficient, by showing that their overhead is at least two orders of magnitude smaller than that of a na\"ive approach, for cases where the monitored aggregate is sufficiently far from the threshold. Third, we present a gossip-based protocol for resource management in cloud environments. The protocol allocates CPU and memory resources to sites that are hosted by the cloud. We prove that the resource allocation computed by the protocol converges exponentially fast to an optimal allocation, for cases where sufficient memory is available. Through simulations, we show that the quality of the resource allocation approaches that of an ideal system when the total memory demand decreases significantly below the memory capacity of the entire system. In addition, we validate that the quality of the allocation does not change with increasing the number of hosted sites and machines, for the case where both metrics are scaled proportionally. Finally, we compare two approaches (tree-based and gossip-based) to engineering protocols for distributed management, for the case of real-time monitoring. Results of our simulation studies indicate that, regardless of the system size and failure rates in the monitored system, gossip protocols incur a significantly larger overhead than tree-based protocols for achieving the same monitoring quality (e.g., estimation accuracy or detection delay). / QC 20101124
78

A Middleware for Self-Managing Large-Scale Systems

Adam, Constantin January 2006 (has links)
This thesis investigates designs that enable individual components of a distributed system to work together and coordinate their actions towards a common goal. While the basic motivation for our research is to develop engineering principles for large-scale autonomous systems, we address the problem in the context of resource management in server clusters that provide web services. To this end, we have developed, implemented and evaluated a decentralized design for resource management that follows four principles. First, in order to facilitate scalability, each node has only partial knowledge of the system. Second, each node can adapt and change its role at runtime. Third, each node runs a number of local control mechanisms independently and asynchronously from its peers. Fourth, each node dynamically adapts its local configuration in order to optimize a global utility function. The design includes three fundamental building blocks: overlay construction, request routing and application placement. Overlay construction organizes the cluster nodes into a single dynamic overlay. Request routing directs service requests towards nodes with available resources. Application placement partitions the cluster resources between applications, and dynamically adjusts the allocation in response to changes in external load, node failures, etc. We have evaluated the design using complexity analysis, simulation and prototype implementation. Using complexity analysis and simulation, we have shown that the system is scalable, operates efficiently in steady state, quickly adapts to external events and allows for effective service differentiation by a system administrator. A prototype has been built using accepted technologies (Java, Tomcat) and evaluated using standard benchmarks (TPC-W and RUBiS). The evaluation results show that the behavior of the prototype matches closely that of the simulated design for key metrics related to adaptability and robustness, therefore validating our design and proving its feasibility. / QC 20100629
79

Transportation Costs in Centralized and Decentralized Structure : A case study at Rottne Industri AB

Monteforte, Giorgio, Monits, Veronika, Croizat-Viallet, Thomas January 2013 (has links)
Background: Rottne Industri is a Swedish heavy machinery manufacturer whose production process is divided in three manufacturing plants. The production takes place in the facilities of Stensele and Lenhovda while the one at Rottne is also used for the final assembly. Ten suppliers provide steel materials to each facility translating to relatively high transportation costs which may be reduced by adopting a more centralized structure. Purpose: The purpose of this paper is to identify the transportation costs between the steel suppliers and the three manufacturing plants at Stensele, Lenhovda and Rottne as well as the freight transportation costs for components from Stensele and Lenhovda to Rottne. Moreover, the research seeks to analyze the difference in transportation costs if Rottne Industri was to centralize all its activities into one single manufacturing facility at Rottne. Finally, the authors aim to identify the environmental cost related to freight transportation in order to evaluate the total transportation cost difference between the two scenarios. Method: The Master thesis focuses on an instrumental case study on a single company. Qualitative and quantitative research methods are used for the necessary data collection to bring up a broader picture of Rottne Industri transportation costs and how it will change in a different organizational structure. Results: The studied company would reduce its freight transportation cost from 2 471 735 SEK of the current decentralized structure to 398 265 SEK of the centralized one. The environmental cost would decrease by 91% (20 420 SEK) due to the decrease of material flow. Therefore Rottne Industri would reduce its total transportation costs by 84% by centralizing its manufacturing structure, for a monetary value estimated at 2 095 860 SEK. However these results contradict part of the theoretical framework concerning the advantages and the disadvantages of centralization and decentralization, as the new centralized structure appears to be more easily manageable while reducing the transportation costs from the different suppliers. Therefore further researches are required as a broader approach on the effects of switch in the organizational structure at Rottne Industri.
80

Analysis of Centralized and Decentralized Communication and Decision Making for Cooperating Autonomous UAVs

Hagelin, Philip January 2011 (has links)
This thesis describes the work performed at Saab Aeronautics in Linkoping during 2011. The work was to study and develop distributed and centralized methods for analysis of the decision making in a group of unmanned aerial vehicles (UAVs). In addition to this, some simple scenarios were studied and the work was implemented in C++ as the simulator ComDec. The literature review presented in the report provides knowledge of strategies for collaborative UAVs (communication and decision making), understanding of the problems/constraints that are relevant for data links and insight into the algorithms for decision making and autonomy. This work has resulted in a theoretical analysis of suitable design for decision making in a group of interacting autonomous UAVs. Existing methods for distributed and centralized decision making are implemented and a demonstration ofthe outcome are presented in the thesis. It is further shown how various communication problems and disturbances affect the decision making process. Finally, advantages and disadvantages of the selected strategies (communication and decision making) are discussed.

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