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Geykhman, Roman. "Optimal placement of binary actuators in deformable optical systems". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67794.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-113).
Recently, exploration has been conducted into the applicability of binary mechatronics to active figure correction in large optical systems such as space telescopes and ground-based solar-thermal concentrators. This Thesis will continue this exploration. The information-theoretic requirements of the corrective commands required in active optics will be explored to understand the dimensionality of the continuous workspace sampled by binary actuation. In both the minimal expected error and the minimal computation time sense, the optimal discrete workspace is the uniform discrete distribution. A rigorous analogy between binary mechatronics and discrete random variables will be used to show that this optimal workspace is achievable by a linear superposition of actuators with exponentially decreasing influences on the optical surface. It will be proven that elasticity can be exploited to construct mechanisms where constant magnitude actuators exhibit exponentially decaying influences on certain parts of the mechanism, allowing for designs where individual binary actuators correspond to binary bits of the required deformation. A planar truss mechanism designed with this philosophy will be presented and shown to have independent kinematic control of multiple adjacent displacements on its top side. Finally, this design will be shown extend to three dimensions in a manner applicable to optical figure correction. Due to the complexity of mechanisms that meet the optimality criteria, only theoretical analysis will be presented.
by Roman Geykhman.
S.M.
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Lessard, Dominic. "Optimal polygon placement on a grid". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0028/MQ52380.pdf.
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Ratul, Saiful A. "Optimal DG Placement: A Multimethod Analysis". ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2269.
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With Power System being restructured in the vision of Smart Grid, it is important now more than ever to find suitable locations to place Distributed Generators (DG). Distributed generators, which may be renewable, are not limited to specific locations as in the case of conventional generators. Several papers have been published that make suggestions on where the optimal location of DG should be in a system. Objectives ranging from loss minimization to total cost minimization have been the factor for such studies. In this study, a new method is introduced that hopes to improve a current system in three ways by maximizing load, minimizing the locational marginal price and improving line contingency scenarios. The proposed methodology is simulated using MATPOWER’s Optimal Power Flow on the IEEE 14 bus test system.
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Lessard, Dominic Carleton University Dissertation Computer Science. "Optimal polygon placement on a grid". Ottawa, 2000.
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Cameron, Alexander John. "A Bayesian approach to optimal sensor placement". Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:ad201132-d418-4ee4-a9d5-3d79bd4876a7.
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By "intelligently" locating a sensor with respect to its environment it is possible to minimize the number of sensing operations required to perform many tasks. This is particularly important for sensing media which provide only "sparse" data, such as tactile sensors and sonar. In this thesis, a system is described which uses the principles of statistical decision theory to determine the optimal sensing locations to perform recognition and localization operations. The system uses a Bayesian approach to utilize any prior object information (including object models or previously-acquired sensory data) in choosing the sensing locations.
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Movva, Gopichand. "Optimal Sensor Placement for Structural Health Monitoring". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700010/.
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In large-scale civil structures, a limited number of sensors are placed to monitor the health of civil structures to reduce maintenance, communication and energy costs. In this thesis, the problem of optimal sensor location placement to infer the health of civil structures is explored. First, a comparative study of approaches from the fields of control engineering and civil engineering is conducted . The widely used civil engineering approaches such as effective independence (EI) and modal assurance criterion (MAC) have limitations because of the negligence of modes and damping parameters. On the other hand, control engineering approaches consider the entire system dynamics using impulse response-type sensor measurement data. Such inference can be formulated as an estimation problem, with the dynamics formulated as a second-order differential equation. The comparative study suggests that damping dynamics play significant impact to the selection of best sensor location---the civil engineering approaches that neglect the damping dynamics lead to very different sensor locations from those of the control engineering approaches. In the second part of the thesis, an initial attempt to directly connect the topological graph of the structure (that defines the damping and stiffness matrices) and the second-order dynamics is conducted.
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Nicholas, Paul J. "Optimal transmitter placement in wireless mesh networks". Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://handle.dtic.mil/100.2/ADA501886.
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Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Alderson, David. "June 2009." Author(s) subject terms: Wireless Mesh Networks, Humanitarian Assistance, Disaster Relief, Distributed Operations, Enhanced Company Operations, Network Design, Nonlinear Programming, Terrain Integrated Rough Earth Model, TIREM, Hata COST-231, Simultaneous Routing and Resource Allocation, Dividing Rectangles, DIRECT, Access Points, Access Point Placement, C++ Description based on title screen as viewed on July 13, 2009. Includes bibliographical references (p. 119-122). Also available in print.
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Yang, Xun. "Optimal generator placement in a distributed network". Thesis, Yang, Xun (2016) Optimal generator placement in a distributed network. Honours thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/33968/.
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Since the industrial and residential huge demand for electricity, as well as higher requirements for the electricity reliability and power quality. Meanwhile, the world has been in the energy crisis, the power shortage, and a large area often experienced blackouts accident. All exposed the deficiencies of ‘centralized power’. Thus, the approaches of reducing active power loss in power systems have become increasingly important.
Among them, the method of the optimal location and size of distribution generators in a distributed network is one of the most prospective approaches in the future. And it can use into practice to achieve the purpose of low-carbonate, less cost and flexible power generation power systems because install DGs at the optimal location and with optimal size in distributed network can dramatically reduce active power loss in power systems. There are several models and methods have been suggested for solving the optimal DG placement problem. This paper presents models and methods applied to solve the optimal DG placement problem, and especially propose a new approach that based on an exact solution method using the enumerative method to reduce the number of the combination by request of constraints. In this case, the proposed method firstly will be applied to the simple 6 buses system, and then applied to 14 buses real size distribution network model which is based on the 126 buses real size distribution system. It can be evaluated for active power loss reduction features by DGs installation and choose optimal location and size of distribution generation in distributed network considering actual use.
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Shankar, Arun. "Optimal jammer placement to interdict wireless network services". Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://handle.dtic.mil/100.2/ADA483583.
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Thesis (M.S. in Operations Research and M.S. in Applied Mathematics)--Naval Postgraduate School, June 2008.Thesis Advisor(s): Alderson, David ; Zhou, Hong. "June 2008." Description based on title screen as viewed on August 22, 2008. Includes bibliographical references (p. 39-40). Also available in print.
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Kuhn, Tobias Uwe. "Optimal sensor placement in active multistatic sonar networks". Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42665.
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Approved for public release; distribution is unlimitedRecently the idea of deploying non-collocated sources and receivers in multistatic sensor networks (MSNs) has emerged as a promis-ing area of opportunity in sonar systems. This thesis addresses point coverage sensing problems in MSNs, where a number of points of interest have to be monitored in order to protect them from hostile underwater assets. We consider discrete cookie cutter sensors as well as various diffuse sensor models. By showing that the convex hull spanned by the targets is guaranteed to contain optimal sensor positions, we are able to limit the solution space. Using a cookie cutter sensor model, we are able to exclude even more suboptimal solutions by determining range-of-the-day, source and receiver circles. To address the nonconvex single-source placement problem, we develop the Divide Best Sector (DiBS) algorithm, which quickly provides an optimal source position assuming fixed receivers. Starting with a basic implementation of DiBS, we show how incorpo-rating advanced sector splitting methods and termination conditions further improve the algorithm. We also discuss two ways to use DiBS to find multiple source positions by placing sensors iteratively or simultaneously. Finally, we conclude that DiBS is a fast and simple algorithm that supports a wide variety of sensor models, various termination conditions, and objective functions.
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Ma, San-San. "Optimal Taxi Placement Using a Maximal Covering Approach". Thesis, KTH, Optimeringslära och systemteori, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233578.
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Taxi placement problem is a problem where a number of available taxi vehicles needs to be placed in an area with the objective of covering as much of the demand population as possible in order to acquire as many customer orders as possible. This study tries to model the taxi placement problem as maximum covering location problem (MCLP) and solve it with the heuristic methods, greedy adding (GA) algorithm and local search. The model implementation and solution methods were formulated with adjustments and key assumptions to fit the core problem of taxi placement problem. The performance of model and solution methods were examined in terms of solution quality and run time. Results found that GA algorithm gave high quality solution with relatively low run time and that local search improved on GA solution by around 1,6% on average but suffered from long run times. The testing concluded that there is potential in modelling the taxi placement problem as a MCLP model but the current implementation has potential problems such as discretization not being fine enough and that it relies on several key assumptions. If the key assumptions were to not hold, the problem becomes more complex and/or adjustments needs to be made to reflect it.Taxiplaceringsproblemet är ett problem där ett antal tillgängliga taxibilar behöver placeras inom ett område med målet att täcka så mycket som möjligt av efterfrågan och öka antal kundordrar som fås. Denna studie försöker modellera taxiplaceringsproblemet som en maximum covering location problem (MCLP) och lösa det med heuristiska metoderna greedy adding (GA) algoritmen och local search. Implementationen av modell samt lösningsmetoderna formulerades med justeringar och nyckelantaganden för att passa kärnproblemet av taxiplaceringsproblemet. Därefter värderades prestandan av modellen och lösningsmetoderna utifrån lösningskvalitet och körtid. Resultaten visade att GA algoritmen gav hög kvalitet i lösning och hade relativt snabb körtid medan local search förbättrade GA lösningen med cirka 1,6% men hade en lång körtid. Testerna visade att det finns potential i att modellera taxiplaceringsproblemet som ett MCLP modell men den nuvarande implementationen har potentiella problem så som diskretiseringen inte är tillräckligt bra och att modellen är beroende av vissa nyckelantaganden. Om dessa nyckelantaganden inte skulle gälla längre kan problemet bli mer komplext och/eller behöver problemet justeras för att ta hänsyn till det.
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Madamori, Oluwashina. "Optimal Gateway Placement in Low-cost Smart Cities". UKnowledge, 2019. https://uknowledge.uky.edu/cs_etds/92.
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Rapid urbanization burdens city infrastructure and creates the need for local governments to maximize the usage of resources to serve its citizens. Smart city projects aim to alleviate the urbanization problem by deploying a vast amount of Internet-of-things (IoT) devices to monitor and manage environmental conditions and infrastructure. However, smart city projects can be extremely expensive to deploy and manage partly due to the cost of providing Internet connectivity via 5G or WiFi to IoT devices. This thesis proposes the use of delay tolerant networks (DTNs) as a backbone for smart city communication; enabling developing communities to become smart cities at a fraction of the cost. A model is introduced to aid policy makers in designing and evaluating the expected performance of such networks and results are presented based on a public transit network data-set from Chapel Hill, North Carolina and Louisville, Kentucky. We also demonstrate that the performance of our network can be optimized using algorithms associated on set-cover and Influence maximization problems. Several optimization algorithms are then developed to facilitate the effective placement of gateways within the network model and these algorithms are shown to outperform traditional centrality-based algorithms in terms of cost-efficiency and network performance. Finally, other innovative ways of improving network performance in a low-cost smart city is discussed.
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Hasan, Md Mahmud. "Optimal Cyber Security Placement Schemes for Smart City Infrastructures". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36199.
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The conceptual evolution of smart cities is highly motivated by the advancement of information and communication technologies (ICTs). The purpose of a smart city is to facilitate the best quality of life to its inhabitants. Its implementation has to be supported by the compliant utilities and networked infrastructures. In the current world, it can only be achieved by applying ICTs in an extensive manner. The move towards the smart city's seamless connectivity widens the scope of cyber security concerns. Smart city infrastructures to face a high risk of targeted attacks due to extended cyber-physical vulnerabilities. This creates many challenging research issues relevant to the design and implementation of cyber security solutions. Networks associated with city infrastructures vary from a small indoor one to a large geographically distributed one. The context of a network is an essential consideration for security solutions. This thesis investigates a set of optimal security placement problems for enhancing monitoring in smart city infrastructures. It develops solutions to such placement problems from a resource management perspective. Economy and quality-of-security service (QoSS) are two major design goals. Such goals are translated into three basic performance metrics: (i) coverage, (ii) tolerance, and (iii) latency. This thesis studies security placement problems pertaining to three different types of networks: (i) wireless sensor network (WSN), (ii) supervisory control and data acquisition (SCADA) backbone, and (iii) advanced metering infrastructure (AMI) wide area network (WAN). In a smart city, WSNs are deployed to support real time monitoring and safety alert (RTMSA) applications. They are highly resource constrained networks. For WSNs, placement problems for an internally configured security monitor named watchdog have been studied. On the other hand, a smart grid is a key driver for smart cities. SCADA and AMI are two major components of a smart grid. They are associated with two different types of geographically distributed networks. For SCADA backbones, placement problems for a specially designed security device named trust system have been studied. For AMI-WANs, placement problems for a cloud-based managed security service have been studied. This thesis proposes a number of promising solution schemes to such placement problems. It includes evaluation results that demonstrate the enhancements of the proposed schemes.
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Rexavier, Raji. "Optimal placement of metal foils in ultrasonic consolidation process". Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1181668872/.
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Zeraatzade, Mahbube. "Transmission congestion management by optimal placement of FACTS devices". Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4710.
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This thesis describes the implementation of the Flexible AC Transmission Systems (FACTS) devices to develop a market-based approach to the problem of transmission congestion management in a Balancing Market. The causes, remedies and pricing methods of transmission congestion are briefly reviewed. Balancing Market exists in markets in which most of the trading is done via decentralized bilateral contracts. In these markets only final adjustments necessary to ensure secure system operation is carried out at a centralized Balancing Market. Each market player can participate in the Balancing Market by submitting offers and bids to increase and decrease its initially submitted active generation output. In this research a method is proposed to reduce costs associated with congestion re-dispatch in a Balancing Market by optimal placement of FACTS devices, and in particular Thyristor Controlled Phase Shifter Transformers (TCPST). The proposed technique is applicable to both Mixed Integer Linear Programming (MILP) and Mixed Integer Non-Linear Programming (MINLP). In the MILP a power system network is represented by a simplified DC power flow under a MILP structure and the Market participants' offers and bids are also represented by linear models. Results show that applications of FACTS devices can significantly reduce costs of congestion re-dispatch. The application of the method based on the MINLP creates a nonlinear and non-convex AC OPF problem that might be trapped in local sub-optima solutions. The reliability of the solution that determines the optimal placement of FACTS devices is an important issue and is carried out by investigation of alternative solvers. The behavior of the MINLP solvers is presented and finally the best solvers for this particular optimization problem are introduced. The application of DC OPF is very common in industry. The accuracy of the DC OPF results is investigated and a comparison between the DC and AC OPF is presented.
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Ur-Rehman, Raza. "Multiobjective optimization of parallel robots and optimal path placement". Ecole centrale de Nantes, 2009. https://hal.archives-ouvertes.fr/tel-01390055.
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Les machines à cinématique parallèle (PKMs en anglais) attirent l'attention de nombreux chercheurs puisqu’elles présentent notamment les avantages suivants :vitesses élevées, bonne précision, faibles inerties et raideur structurelle élevée. Plusieurs machines outils d’architecture innovante sont présentées dans la littérature mais leur utilisation nécessite une analyse approfondie de leurs structure, cinématique et dynamique. Les techniques habituelles de conception peuvent être utilisées pour la conception des PKMs en considérant de manière sommaire des contraintes cinématiques. Un ensemble de solutions non-dominées, appelé ensemble de solutions Pareto optimales, peut être obtenu au moyen de la résolution d’un problème d’optimisation multi-objectif dans lequel les fonctions objectives sont généralement antagonistes. Cela nous permet également de mieux cerner les problèmes de conception complexes. Trois parties distinctes avec comme fil directeur l’optimisation de manipulateurs parallèles sont présentées dans cette thèse. La première partie présente un problème d'optimisation multi-objectif pour la synthèse dimensionnelle de manipulateurs parallèles. Il s’agit de déterminer les paramètres géométriques et structuraux optimaux. L'approche proposée est appliquée à la conception optimale d’un manipulateur parallèle planaire à trois degrés de liberté. La deuxième partie illustre une méthodologie pour le choix des actionneurs de manipulateurs parallèles à l’aide de leurs modèles cinématique et dynamique. Ce travail est réalisé sur la base de l'analyse cinématique et dynamique de l'Orthoglide 5-axes, une machine d’architecture parallèle spatiale dédiée aux opérations d’usinage à grande vitesse conçue à l’IRCCyN. L'analyse est effectuée dans un premier temps pour le poignet sphérique à deux degrés de liberté (ddl) del'Orthoglide 5 axes et ensuite pour le module parallèle de translation, l’Orthoglide 3-axes. Des trajectoires test sont utilisées pour analyser les résultats et une procédure de sélection des moteurs est proposée. La troisième partie de ce mémoire porte sur le placement optimal de trajectoires pour un manipulateur parallèle. Deux problèmes d’optimisation mono et multi-objectifs sont ainsi formulés. Les fonctions objectives de ces problèmes sont : la consommation d'énergie, les couples actionneurs et les sollicitations dynamiques. Une méthode est proposée pourdéterminer le placement optimal d’une trajectoire dans l'espace de travail d'une PKM afin d'optimiser les fonctions objectives précédentes soumises à des contraintes géométriques, cinématiques et dynamiques. La méthodologie proposée est appliquée à l'Orthoglide 3-axes à titre d'exempleParallel Kinematics Machines (PKMs) have attracted attention for their high speed, good accuracy, low mass/inertia properties and high structural stiffness. They are attractive for the innovative machine-tool architectures. However, practicalutilizations for the potential benefits require an extensive and efficient analysis of their structure, kinematics and dynamics. Conventional design techniques may be used for a trivial design of PKMs with a limited capability of considering the performance measures and constraints. A multiobjective optimization approach, on the other hand, can be used to consider a set of optimal trade-off solutions (called Pareto set) between the conflicting design objectives, to better understand the complex design problems. Three separate but inter-linked design optimization issues of parallel manipulators are addressed in this dissertation. Firstly, a multiobjective optimization problem is proposed for the dimensional synthesis of parallel manipulators, in order to determine their optimum structural and geometric parameters. The proposed approach is applied to the optimum design of a three-degree-of-freedom planar parallel manipulator. Secondly, the issue of the actuators selection based on the kinematic and dynamic models of the manipulators is discussed. The process focuses on the kinematic and dynamic analysis of the Orthoglide 5-axis, a spatial PKM developed for high speed operations. The analysis is carried out firstly for the 2-DOF spherical wrist of the Orthoglide 5-axis and then for the 3-DOF translational parallel manipulator, the Orthoglide 3-axis. Some test trajectories are used to analyze the results and a procedure for motors selection is proposed. The last part deals with the optimal path placement of parallel manipulators. Mono- and multi-objective path placement optimization problems for PKMs based on energy consumption, actuators torques and shaking forces are introduced. Accordingly, a methodology is provided to determine the optimal location of a given test path withinthe workspace of a PKM to optimize some objective functions subject to the geometric, kinematic and dynamic constraints of the PKM. The proposed methodology is applied to the Orthoglide 3-axis as an illustrative example
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MAJED, RIADH. "Placement optimal d'excitateurs et modelisation de structures non-lineaires". Besançon, 1995. http://www.theses.fr/1995BESA2069.
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Les recherches presentees dans ce memoire concernent l'apport de nouvelles contributions a la preparation des essais mecaniques en vue de resoudre quelques difficultes liees aux problemes d'identification modale et a la modelisation de structures non-lineaires. Premiere partie: placement optimal d'excitateurs. Cette partie est consacree au developpement d'une methode de positionnement des excitateurs en vue de recalage parametrique de modeles de calcul. Cette methode est basee sur un procede combinatoire et repose sur un modele aux elements finis de precision raisonnable. Elle a pour but de chercher les meilleures repartitions des degres de liberte excitateurs conduisant une excitation simultanee des modes presents dans la bande frequentielle. Les performances de la methode ont ete evaluees par des applications a un cas test et a une structure industrielle. L'exploitation de la methode conduit egalement a une amelioration de la qualite d'expansion obtenue au moyen de deux methodes proposees pour la reconstitution des matrices de souplesse dynamique. Deuxieme partie: modelisation de structures non-lineaires. Dans cette partie on presente une etude analytico-experimentale de prediction des reponses frequentielles de modeles simples a quelques degres de liberte presentant des non-linearites locales et multiples. Cette etude permet d'evaluer les difficultes liees a l'introduction des non-linearites locales, puis de choisir et de valider les methodes et les algorithmes numeriques de resolution. La suite du memoire concerne la modelisation et la simulation d'un modele tridimensionnel non-lineaire de vehicule automobile. Cette etude conduit au developpement d'un outil numerique permettant de simuler le comportement non-lineaire d'un vehicule automobile soumis a des excitations sinusoidales au niveau des pneumatiques
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Firouzabadi, Sina. "Jointly optimal placement and power allocation of wireless networks". College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/8652.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Kouhbor, Shahnaz University of Ballarat. "Optimal number and placement of network infrastructure in wireless networks". University of Ballarat, 2007. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/12762.
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Wireless Local Area Networks (WLANs) have become a major success in telecommunications during the last few years, due to advantages such as mobility, flexibility, and easier maintenance. A device called an access point (AP) acts as a base station in WLAN for connecting a group of users to the network via radio signal. During the planning of such a network an important problem is to determine the optimal number of these devices and their placement/distribution so that coverage, capacity, and physical security are maximised at minimum cost. In this thesis we are using continuous optimisation techniques to optimise the number of APs and their distribution while cost of deployment is reduced and physical security of the network is enhanced. To find the number and placement of APs, we developed a multi-objective functions model based on path losses and power for free space environments. The two functions in the models are combined by using a balancing parameter. Since it is recognised that some of the objectives can be handled one at a time, in another approach, we followed a step-by-step procedure. We start with a novel optimisation model based on path losses for indoor environments including obstacles. Cost of deployment is saved by finding the minimum number of APs ensuring that the path loss at each test point/receiver is below the given maximum path loss. Next, the physical security of the network is enhanced by placing the APs far from places accessible to unauthorised users to reduce the risk of intrusion into the network. This is achieved in the framework of the model by introducing potential unauthorised users in unauthorised areas for whom coverage is minimised. Due to the presence of obstacles in indoor buildings, the path loss function is discontinuous. Therefore, the objective functions are very complicated and most of the existing optimisation algorithms cannot be applied to solve the problem. We use a global optimisation algorithm that is not used by other researchers to solve the same problem. To validate the accuracy of the optimisation model and performance of the numerical methods, we run tests on several indoor buildings and use wide range of WLAN parameters. The results demonstrate the quality of our model and algorithm. Based on the proposed model and algorithm, we developed a software to assist the network designers in planning wireless LANs.Doctor of Philosophy
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Kouhbor, Shahnaz. "Optimal number and placement of network infrastructure in wireless networks". University of Ballarat, 2007. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/14597.
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Wireless Local Area Networks (WLANs) have become a major success in telecommunications during the last few years, due to advantages such as mobility, flexibility, and easier maintenance. A device called an access point (AP) acts as a base station in WLAN for connecting a group of users to the network via radio signal. During the planning of such a network an important problem is to determine the optimal number of these devices and their placement/distribution so that coverage, capacity, and physical security are maximised at minimum cost. In this thesis we are using continuous optimisation techniques to optimise the number of APs and their distribution while cost of deployment is reduced and physical security of the network is enhanced. To find the number and placement of APs, we developed a multi-objective functions model based on path losses and power for free space environments. The two functions in the models are combined by using a balancing parameter. Since it is recognised that some of the objectives can be handled one at a time, in another approach, we followed a step-by-step procedure. We start with a novel optimisation model based on path losses for indoor environments including obstacles. Cost of deployment is saved by finding the minimum number of APs ensuring that the path loss at each test point/receiver is below the given maximum path loss. Next, the physical security of the network is enhanced by placing the APs far from places accessible to unauthorised users to reduce the risk of intrusion into the network. This is achieved in the framework of the model by introducing potential unauthorised users in unauthorised areas for whom coverage is minimised. Due to the presence of obstacles in indoor buildings, the path loss function is discontinuous. Therefore, the objective functions are very complicated and most of the existing optimisation algorithms cannot be applied to solve the problem. We use a global optimisation algorithm that is not used by other researchers to solve the same problem. To validate the accuracy of the optimisation model and performance of the numerical methods, we run tests on several indoor buildings and use wide range of WLAN parameters. The results demonstrate the quality of our model and algorithm. Based on the proposed model and algorithm, we developed a software to assist the network designers in planning wireless LANs.Doctor of Philosophy
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PLUMET, FREDERIC. "Controle dynamique et placement de taches optimal pour manipulateurs rapides". Paris 6, 1992. http://www.theses.fr/1992PA066583.
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Le controle dynamique de manipulateurs rapides et la definition de trajectoires optimales en precision et temps de parcours sont abordes dans ce travail. L'integration du modele dynamique d'un manipulateur a la fonction de generation des trajectoires permet de determiner la loi de parcours optimale en temps d'une trajectoire geometrique donnee. L'amelioration des performances de suivi est obtenue par une approche originale, les lignes de moindres perturbations. Cette methode etablit l'existence de directions de l'espace selon lesquelles les effets perturbateurs lies aux couplages dynamiques n'induisent pas d'erreur lors du suivi de trajectoires. Une application au placement optimal de taches est proposee. Le modele dynamique du manipulateur est utilise explicitement dans les schemas de controle en position du manipulateur. Deux schemas de controle dynamique (commande par decouplage non lineaire et commande predictive) sont mis en uvre sur un manipulateur industriel et leurs performances sont comparees experimentalement tant en ce qui concerne la precision que le temps de cycle
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Khiabani, Vahidhossein. "Multi-Objective Optimal Phasor Measurement Units Placement in Power Systems". Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27029.
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The extensive development of power networks has increased the requirements for robust, reliable and secure monitoring and control techniques based on the concept of Wide Area Measurement System (WAMS). Phasor Measurement Units (PMUs) are key elements in WAMS based operations of power systems. Most existing algorithms consider the problem of optimal PMU placement where the main objective is to ensure observability. They consider cost and observability of buses ignoring the reliability aspect of both WAMS and PMUs. Given the twin and conflicting objectives of cost and reliability, this dissertation aims to model and solve a multi-objective optimization formulation that maintains full system observability with minimum cost while exceeding a pre-specified level of reliability of observability. No unique solution exists for these conflicting objectives, hence the model finds the best tradeoffs. Given that the reliability-based PMU placement model is Non-deterministic Polynomial time hard (NP-hard), the mathematical model can only address small problems. This research accomplishes the following: (a) modeling and solving the multi-objective PMU placement model for IEEE standard test systems and its observability, and (b) developing heuristic algorithms to increase the scalability of the model and solve large problems. In short, early consideration of the reliability of observability in the PMU placement problem provides a balanced approach which increases the reliability of the power system overall and reduces the cost of reliability. The findings are helpful to show and understand the effectiveness of the proposed models. However the increased cost associated with the increased reliability would be negligible when considering cost of blackouts to commerce, industry, and society as a whole.
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Essien, Mmekutmfon Sunday. "A multiobjective optimization model for optimal placement of solar collectors". Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/30954.
Texto completoResumen
The aim and objective of this research is to formulate and solve a multi-objective optimization problem
for the optimal placement of multiple rows and multiple columns of fixed flat-plate solar collectors
in a field. This is to maximize energy collected from the solar collectors and minimize the
investment in terms of the field and collector cost. The resulting multi-objective optimization problem
will be solved using genetic algorithm techniques.
It is necessary to consider multiple columns of collectors as this can result in obtaining higher amounts
of energy from these collectors when costs and maintenance or replacement of damaged parts are
concerned. The formulation of such a problem is dependent on several factors, which include shading
of collectors, inclination of collectors, distance between the collectors, latitude of location and the
global solar radiation (direct beam and diffuse components). This leads to a multi-objective optimization
problem. These kind of problems arise often in nature and can be difficult to solve. However
the use of evolutionary algorithm techniques has proven effective in solving these kind of problems.
Optimizing the distance between the collector rows, the distance between the collector columns and
the collector inclination angle, can increase the amount of energy collected from a field of solar collectors
thereby maximizing profit and improving return on investment.
In this research, the multi-objective optimization problem is solved using two optimization approaches
based on genetic algorithms. The first approach is the weighted sum approach where the
multi-objective problem is simplified into a single objective optimization problem while the second
approach is finding the Pareto front.Dissertation (MEng)--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
MEng
Unrestricted
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BUSCH, ROBYN M. "PREDICTING OPTIMAL HOUSING PLACEMENT FOR PEOPLE WITH SERIOUS MENTAL ILLNESSES". University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1028044502.
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Wailly, Olivier. "Placement optimal de capteurs sur un système à modèle polynomial". Corte, 2004. http://www.theses.fr/2005CORT3091.
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La présente thèse met en évidence une méthode novatrice dans le placement de capteurs sur un système automatisé. Cette méthode n'est applicable que sur les systèmes présentant un modèle polynomial. Cette méthode est innovante dans l'utilisation du calcul formel, et plus spécifiquement des algorithmes des bases de Groëbner. Après avoir montré comment il est possible, utile et interressant d'utiliser le calcul formel, il est développé une recherche de placement prenant en compte des critères optimums. Ainsi, des algorithmes avec critères de coût et critères de fiabilité sont élaborésThe present thesus present a novel method in sensor design on automated system. This method is only applicable on polynomial systems. This method is using symbolic calculus software. Especially, the Groënberg bases' algorithms are used. After showing the interest of this method, algoritms and programs with optimal criteria are presented. So, the criteria like cost and reliability are developed
26
Gelotte, Lovisa y Nilsson Alexandra Lundevall. "Optimal Placement of FloatingTwo-Turbine Foundations in Offshore Wind Farms". Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209833.
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This project is conducted in cooperation with Hexicon AB, which is a Swedish design and engineering company developing floating two-turbine platforms for offshore wind power.The study aims to investigate the optimal placement of Hexicon AB’s platforms in an offshore wind farm with respect to the Annual Energy Production (AEP). Wind farm layout optimization is a complex problem and it has been approached by the development of calculation and optimization programs in Matlab. The analytical Jensen wake model has been utilized for calculation of AEP and important inputs to the program have been turbine parameters and site specific conditions. The optimization strategy used is a multi-stage algorithm where the gradient-based local search algorithm Fmincon has been used in combination with a version of the heuristic genetic algorithm. The developed programs have been tested and evaluated through a case study. Included in the case study is also a brief financial evaluation regarding how different scenarios in electricity export price and costs for cabling could affect the feasibility of the optimized layouts. Concluded from the project is that the developed programs can be used to investigate the optimal placement of floating two-turbine platforms with respect to AEP. In the case study it was found that the optimized layout obtained a wind farm efficiency of around 4% more than for the conventional staggered layout that was tested. What is also emphasized is that the feasibility of the optimized layouts obtained from the program is quite sensitive toward changes in future electricity export price and costs for cabling and installation. Hence, it is important to perform a careful financial analysis in order to draw conclusions regarding what layout is the better option for a specific situation.Dagens utbyggnad av vindkraft sker i allt större utsträckning genom etablering av vindkraftparker. De främsta fördelarna med att placera vindkraftverken i parker är att de höga fasta kostnaderna fördelas på flera kraftverk samt att man kan beställa ett flertal enheter samtidigt och därigenom minska kostnaden per installerad Megawatt (MW). För att ytterligare kunna öka vinsten på investeringen är det viktigt att undersöka optimal inbördes placering av vindkraftverken för att erhålla en så hög energiproduktion som möjligt. Det finns många studier gjorda inom området och ett flertal programvaror utvecklade. Dock finns det endast ett fåtal studier som har inriktat sig specifikt på flytande vindkraftverk. Detta arbete är utfört i samarbete med Hexicon AB, vilket är ett Stockholmsbaserat ingenjörsföretag som utvecklar en patenterad teknik för plattformar avsedda för flytande vindkraft. Det unika med Hexicon ABs patenterade teknik är att två vindkraftverk är placerade på en gemensam plattform. Denna teknik gör det möjligt för plattformen att anpassa sig till vindriktningen vilket ger en ökning av kraftverkens energiutbyte. Då det inte finns några utvecklade optimeringsmetoder för flytande plattformar som kan anpassa sig efter vindriktning är syftet för denna studie att undersöka den optimala inbördes placeringen av Hexicon ABs plattformar i en vindkraftpark. Eftersom vindkraftsoptimering är ett komplicerat problem som bland annat är icke-linjärt och icke-konvext så finns det ingen exakt lösning tillgänglig för problemet. Komplexiteten gör även många förenklingar och antaganden nödvändiga för att kunna bearbeta problemet. I detta projekt har sambandet mellan årlig elproduktion och inbördes placering av plattformarna undersökts genom att ett kalkylerings- och optimeringsprogram utvecklats i programvaran Matlab. För att kunna undersöka den optimala inbördes placeringen av vindkraftverken är det viktigt att förstå hur vindkraftverken påverkas av att placeras tillsammans i en park. För att göra detta så behövs en modell för att beskriva den så kallade vaken som uppstår bakom respektive vindkraftverk. Detta gjordes genom att använda den analytiska Jensen vakmodellen, vilket är den vanligaste modellen att använda för optimeringssyften. Beräkningen av elproduktion gjordes baserat på given information angående turbinparametrar samt specifika förhållanden på platsen för vindparken. För det utvecklade optimeringsprogrammet användes en tvåstegsalgoritm där den gradientbaserade algoritmen Fmincon utgjorde den centrala delen. Fmincon är en effektiv algoritm för lokal optimering som finns tillgänglig i Matlab. För att generera bra startgissningar till den lokala optimeringen användes en version av en heuristisk genetisk algoritm som komplement till Fmincon. Denna algoritm bygger på samma princip som processen för naturligt urval i evolutionssammanhang där de bäst lämpade individerna för vidare sina egenskaper till nästa generation. För att ytterligare förbättra algoritmen kompletterades den även med ett moment av slumpmässighet. För att testa och utvärdera de utvecklade programmen genomfördes en fallstudie. I denna studie optimerades 50 stycken olika heuristiska startgissningar. De 20 bäst presterande konfigurationerna valdes ut för vidare analys där de blev utvärderade med avseende på olika scenarion för elpris samt kostnad för elektrisk infrastruktur. Detta för att undersöka hur den optima placeringen eventuellt skulle kunna påverkas av osäkerheter i dessa faktorer. Den genomförda fallstudien indikerade att de utvecklade programmen kan användas för att undersöka den inbördes optimala placeringen av vindkraftverk med avseende på elproduktion. Den ekonomiska utvärderingen indikerade även att den optimala placeringen var känslig för olika scenarion där elpris och kostnader för infrastruktur varierades och att detta kunde påverka lönsamheten för investeringen. Det ska därför betonas att det anses vara viktigt att utföra en mer noggrann ekonomisk utvärdering av de optimerade konfigurationerna för att undersöka vilken positionering som är mest lämplig för en viss situation.
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Banik, Bijit Kumar. "Sewer systems management : illicit intrusion identification and optimal sensor placement". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1112/document.
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La gestion incorrecte des eaux usées peut entraîner des dommages importants sur les stations de traitement et sur le récepteur final (écosystème aquatique). Dans le passé, la gestion des eaux usées n'a pas retenu beaucoup d'attention de la part des différentes parties prenantes. Toutefois, récemment, le changement de modèle de gestion des eaux usées et des eaux pluviales, a évolué du simple contrôle sanitaire et des inondations, à une protection globale de l'environnement. Un aspect très important, dans la politique de gestion des systèmes d'assainissement, est de détecter et d'éliminer une intrusion illicite, qui peut être intentionnelle. Ce travail thèse de doctorat est constitué de deux parties principales. Dans la première partie les problèmes relatifs à l'identification d'une intrusion illicite dans un système d'assainissement ont été abordés, proposant une méthodologie d'identification de la source (IS). Dans la deuxième partie, différentes méthodologies innovantes ont été proposées pour trouver l'emplacement optimal d'un nombre limité de capteurs dans le système d'assainissement. Dans cette thèse, le ISest résolu grâce à un modèle de simulation-optimisation, combinant l'outil de simulation Storm Water Management Model (SWMM) avec un code d'optimisation basé sur un algorithme génétique (Galib). Ceci nécessite des mesures en ligne de certains capteurs placés sur le réseau. Le SWMM ne possède pas l'outil de programmation. Afin d'intégrer le simulateur SWMM à la méthodologie de IS automatisé proposée, un outil ad-hoc a été développé. Une procédure de présélection, basée sur le concept de la matrice de la pollution et compte tenu de la topologie des égouts, a été mis en œuvre pour réduire l'effort de calcul. La méthodologie IS a été testée sur deux réseaux différents. L'un est un réseau connu dans la littérature, extrait du manuel de SWMM, tandis que l'autre réseau est un sous-bassin versant du réseau d'assainissement de Massa Lubrense, village situé près de Naples, en Italie. Les résultats montrent que les procédures de présélection réduisent considérablement l'effort de calcul, avec un rôle crucial pour les grands systèmes. En enquêtant sur la performance de la méthodologie IS, sa sensibilité par rapport aux paramètres de l'algorithme génétique a été vérifiée. En outre, l'influence de l'incertitude des flux entrés et des erreurs de mesure sur les résultats ont été approfondi. Un autre problème fondamental, associé à la surveillance de la qualité de l'eau des égouts, est le placement optimal d'un nombre limité de capteurs pour la détection précoce d'une source illicite. Dans la thèse l'emplacement du capteur est exprimé avec un problème d'optimisation mono ou multi-objectif. Le SWMM est utilisé pour extraire les données de qualité de l'eau. Différentes formulations ont été proposées et testées. Tout d'abord, la Théorie de l'Information (TI) basée sur la méthodologie d'optimisation multi-objectif est présentée. La TI considère deux objectifs : l'entropie conjointe, le contenu de l'information dans un ensemble de capteurs, qui est maintenu aussi haut que possible ; la corrélation totale, une mesure de la redondance, qui est maintenue aussi faible que possible. Dans la seconde approche multi-objectifs le temps de détection doit être minimisé et la fiabilité qui doit être maximisée. Les deux cas, les problèmes multi-objectifs sont résolues en utilisant l'algorithme Non-Dominating Sorting Genetic Algorithm-II (NSGA-II). Comme troisième alternative, un outil d'optimisation mono-objectif (Greedy) a été testé. Les objectifs précédemment considérées sont utilisés avec différentes combinaisons. Le réseau d'assainissement de Massa Lubrense a été utilisé pour tester les performances des différentes procédures proposées. Une comparaison normalisée entre toutes les approches montre que l'approche basée sur Greedy pourrait être une alternative pratique pour l'optimisation des emplacements de capteurs dans les systèmes d'assainissementImproper wastewater management could result in significant damage to the treatment plants and the final recipient aquatic ecosystem. In the past, wastewater management did not get much attention from different stakeholders. However, recently a paradigm shift of wastewater and storm water management is evolving from a simple sanitary and flood control, respectively, to a whole environmental protection function. A very important aspect of the sewer systems management policy is to detect and eliminate an illicit intrusion. This PhD research is consisting of two main pillars. In the first pillar, the issues regarding the identification of an illicit intrusion in a sewer system have been addressed, proposing a source identification (SI) methodology. In the second pillar, different innovative methodologies have been proposed to find the optimal placement of a limited number of sensors in the sewer system. In the thesis, the SI is solved through a simulation-optimization model, combining the hydraulic and quality simulation tool Storm Water Management Model (SWMM) with a genetic algorithm code (GALib) as an optimizer. It requires online measurements from some sensors placed on the network. The SWMM does not have the programmer's toolkit. To integrate the SWMM simulator with the proposed automated SI methodology, an ad-hoc toolkit has been developed. A pre-screening procedure, based on the pollution matrix concept and considering the topology of sewers, has been implemented to reduce the computational effort. The SI methodology has been tested on two different networks. One is a literature network taken from the SWMM example manual while the other is one sub-catchment of the real sewer network of Massa Lubrense, a town located near Naples, Italy. The results show that the pre-screening procedure reduces the computational effort significantly, and it has a crucial role in large systems. In investigating the performances of the SI methodology, its sensitivity respect to the genetic algorithm parameters has been verified. Moreover, the influence of the uncertainty of the inflows values and the measurement errors on the results have been investigated. Another core problem associated with the water quality monitoring of sewers is represented by the optimal placement of a limited number of sensors for the early detection of an illicit source. In the thesis, the sensor location is expressed as a single or multi-objective optimization problem and the SWMM is used to extract the water quality data. Different formulations have been proposed and tested. First, an Information Theory (IT) based multi-objective optimization methodology is presented. The IT approach considers two objectives: the Joint entropy, the information content of a set of sensors, which is kept as high as possible; the Total correlation, a measure of redundancy, which is kept as low as possible. In the second multi-objective approach Detection time, to be minimized, and Reliability, to be maximized, are considered. In both cases, the multi-objective problems are solved using the Non-Dominating Sorting Genetic Algorithm-II (NSGA-II). As a third alternative, a single objective Greedy based optimization tool has been tested. The previously considered objectives are also used with different combinations. The Massa Lubrense sewer network is used to test the performances of various proposed procedures. A normalized comparison among all approaches shows that the Greedy based approach could be a handy alternative for optimizing the sensor locations in sewer systems
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Marx, David Hercules. "The optimal placement of geogrid reinforcement in landfill clay liners". Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/60633.
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Continued population growth is placing strain on the waste disposal facilities available in South Africa. However, limited air space suitable for landfilling drives the need for alternative solutions such as piggyback landfills to expand the waste disposal capacity. This method entails building a new, fully lined, landfill on top of existing waste. However, the old underlying waste is prone settlement that can result in the cracking of new landfill clay liner.
Geogrid reinforcement have been successfully used in clay liners to mitigate cracking induced by waste settlement. This research focused on investigating of the optimal reinforcement strategy (ORS) of such a liner subject to settlement. The ORS entails the optimal position for geogrid reinforcement in a liner, and the stiffness to be used at that position, given a total reinforcement cost.
Firstly, the fracture behaviour of unreinforced clay liners was investigated by means of four point bending tests on clay beams. It was found that the fracture of this clay occurred in three stages: linear behaviour, followed by non-linear behaviour when micro-cracks forms and finally macro-cracks that opened once the peak load was reached.
Thereafter, the behaviour of geogrid-reinforced clay liners, subjected to differential settlement, was investigated with finite element analyses in ABAQUS. A number of key factors were varied and the resulting change in behaviour of the liners was observed. These were: the overburden stress applied, clay liner thickness, magnitude of central settlement and the width and shape of the settlement trough developing in the underlying waste body.
Based on the numerical results, a series of plane-strain centrifuge tests of reinforced clay liners subject to differential settlement were designed. An unreinforced liner, a liner reinforced at the bottom quarter, a liner reinforced at the top quarter and a liner reinforced at both the bottom and top quarters were tested. Laser scanner scans of the surface and strains calculated from digital image velocimetry results were used to compare the behaviour of the liners. Based on these results it is recommended that for optimal performance the available reinforcement should be divided between the top and bottom quarters of the liner to mitigate the effect of settlement.Volgehoude bevolkingsgroei in Suid-Afrika plaas bestaande rommelstortingsfasiliteite onder druk. ’n Tekort aan grond geskik vir die bou van stortingsterreine moedig die soektog na alternatiewe oplossings soos abba-stortingsterreine aan. Hierdie metode behels ’n splinternuwe stortingsterrein wat bo-op bestaande rommel gebou word. Versakking van die bestaande rommel kan egter veroorsaak dat krake vorm in die nuwe stortingsterrein se kleivoering wat daarop lê. Vorige navorsing het die vorming van krake in die kleivoerings al welgeslaagd verhoed deur van georoosters as versterking gebruik te maak. Die huidige studie het op daardie navorsing gebou deur die optimale versterkings strategie (OVS) te bepaal vir so ’n kleivoering wat vervorm onder versakking van die onderliggende rommel. Die OVS definieer beide die optimale versterkings posisie in ’n kleivoering, en die styfheid van die georooster wat in daardie posisie geplaas moet word, gegewe ’n sekere totale versterkingskoste. Eerstens was daar ondersoek ingestel na die kraakgedrag van onversterkte kleivoerings. Vierpuntbuigtoetse van kleibalkies was hiervoor gebruik. Die krake het oor drie fases gevorm: eerstens was daar lineêre gedrag tot en met mikro-krake gevorm het. Dit is gevolg deur nie-lineêre gedrag wat gelei het tot makro-krake. Sodra die makro-krake gevorm het, is die maksimum las bereik wat die klei kon ondersteun. Na afloop van die balkbuigtoetse was eindige element analises in ABAQUS uitgevoer om die gedrag van versterkte kleivoerings wat bo-op versakkende afval lê te ondersoek. Die spanning toegepas op die oppervlak van die kleivoerings, die dikte van die kleivoerings en die versakkingstrogwydte, -vorm en -diepte was gevarieer om die effek daarvan op die gedrag van die kleivoerings te ondersoek. Na aanleiding van die resultate van die numeriese analise is ’n reeks sentrifuge toetse van kleivoerings wat aan versakking onderwerp word uitgevoer. ’n Onversterkte kleivoering, kleivoerings versterk in die boonste en onderste kwarte, en een versterk in beide die boonste en onderste kwart was getoets. Die gedrag van die verskillende kleivoerings was vergelyk deur die oppervlaktekrake op te meet met ’n laserskandeerder. Verder is die vervorming van die kleivoerings bepaal vanaf die verplasing van die grondpartikels tussen opeenvolgende digitale foto’s. Na aanleiding van hierdie resultate word dit aanbeveel dat die beskikbare georooster versterking opgedeel moet word tussen die boonste en onderste kwart van die kleivoerings ten einde optimale gedrag te verseker indien versakking sou plaasvind.
Dissertation (MEng)--University of Pretoria, 2017.
Deutscher Akademischer Austausch Dienst (DAAD)
Geosynthetics Interest Group of South Africa (GIGSA)
National Research Foundation of South Africa (NRF)
Civil Engineering
MEng
Unrestricted
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Suwit, Pulthasthan Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Optimal placement of sensor and actuator for sound-structure interaction system". Awarded by:University of New South Wales - Australian Defence Force Academy. School of Information Technology and Electrical Engineering, 2006. http://handle.unsw.edu.au/1959.4/38741.
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This thesis presents the practical and novel work in the area of optimal placement of actuators and sensors for sound-structure interaction systems. The work has been done by the author during his PhD candidature. The research is concentrated in systems with non-ideal boundary conditions as in the case in practical engineering applications. An experimental acoustic cavity with five walls of timber and a thin aluminium sheet fixed tightly on the cavity mouth is chosen in this thesis as a good representation of general sound-structure interaction systems. The sheet is intentionally so fixed that it does not satisfy ideal boundary conditions. The existing methods for obtaining optimal sensor-actuator location using analytic models with ideal boundary conditions are of limited use for such problem with non-ideal boundary conditions. The method presented in this thesis for optimal placement of actuators and sensors is motivated by energy based approach and model uncertainty inclusion. The optimal placement of actuator and sensor for the experimental acoustic cavity is used to construct a robust feedback controller based on minimax LQG control design method. The controller is aimed to reduce acoustic potential energy in the cavity. This energy is due to the structure-borne sound inside the sound-structure interaction system. Practical aspects of the method for optimal placement of actuator and sensors are highlighted by experimental vibration and acoustic noise attenuation for arbitrary disturbance using feedback controllers with optimal placement of actuator and sensor. The disturbance is experimentally set to enter the system via a spatial location different from the controller input as would be in any practical applications of standard feedback disturbance rejections. Experimental demonstration of the novel methods presented in this thesis attenuate structural vibration up to 13 dB and acoustic noise up to 5 dB for broadband frequency range of interest. This attenuation is achieved without the explicit knowledge of the model of the disturbance.
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Guha, Thakurta Priyanko. "An Approach for Optimal Placement of SVC to Minimize Load Curtailment". Thesis, KTH, Elektriska energisystem, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119238.
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Modern electric power system is very complex and undergoes unforeseen rapid changes in terms of demand/generation patterns and trading activities that hinder the system security. For example, a steep rise in load or a certain critical line/equipment outage can cause line overload or undesirable voltage profile and such events can push the system towards instability and possibly even a black out. In order to cope with such situations, it is common practice to purchase the rights of asking for a reduction of load from certain customers. However, it is not an ideal situation from reliability perspective, financial as well as having critical load in the power system. Load curtailment is the collection of control strategies employed to reduce the electric power loading in the system and main aim is to push the disturbed system towards a new equilibrium state. Load curtailment may be required even when voltages at some buses are out of their safe operating limits, to prevent a possible voltage collapse. Flexible AC Transmission Systems (FACTS) controllers could be a suitable alternative to provide reactive power support at the load centres locally and hence keep the voltages within their safe operating limits. Due to high costs of FACTS devices, their proper location in the system must be ascertained. To deal with the above problem a new methodology has been proposed, in this thesis, in terms of sensitivity factors for the optimal location of Static Var Compensator (SVC) to minimize the system load curtailment requirements for maintaining the system security. In this work, SVC has been considered for the study to minimize the load curtailment. The effectiveness of the proposed method has been tested on IEEE 14-bus and practical 75-bus Indian systems. Optimal placement have been obtained for the base case loading and to verify its locations, an Optimal Power Flow (OPF) problem has been formulated with an objective to minimize the load curtailment and satisfying all operating constraints along with optimal settings of SVC which is used at suggested places from developed methodology. Moreover, the effects of SVC on load curtailment reduction, which are located at base case loading, have also been investigated for different operating conditions e.g., increased load or having different contractual obligation in the system.
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Bigdeli, Kasra. "Optimal placement and design of passive damper connectors for adjacent structures". Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43015.
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Passive coupling of adjacent structures is known to be an effective method to reduce undesirable vibrations and structural pounding effects. Past results have shown that reducing the number of dampers can considerably decrease implementation costs and does not significantly decrease the efficiency of the system. The main objective of this thesis is the optimal design of a limited number of dampers to minimize the inter-story drift. In this thesis, we present a bi-level optimization algorithm to find the optimal arrangement and mechanical properties of dampers placed between two adjacent buildings to minimize the maximum inter-story drift during (simulated) earthquake conditions.
Under the assumption of equal damping coefficients for all dampers, the optimal damping configuration is found via five different approaches: exhaustive search, inserting dampers, inserting floors, locations of maximum relative velocity, and a genetic algorithm. Through several numerical tests, efficiency and robustness of each optimization method is examined. It is shown that the inserting damper method is the most efficient and reliable method, particularly for tall structures. It is also found that, assuming equal damping coefficients for all dampers, increasing the number of dampers can exacerbate the dynamic response of the system.
Finding an efficient method to optimize dampers’ locations, we focus on the optimization of the damping coefficients. Letting the dampers have varying damping coefficients, the optimization problem of damping coefficients is an n-dimensional optimization problem, whose objective function is provided via a simulation. Therefore, we use non-gradient based techniques for the inner-loop of the algorithm. We compare three different methods: a genetic algorithm (GA), a mesh adaptive direct search (MADS) algorithm, and the robust approximate gradient sampling (RAGS) algorithm. RAGS is a derivative free optimization (DFO) method that exploits the structure of the finite minimax problem. Using these techniques, we show that there exists a threshold on the number of dampers inserted with respect to the efficiency of the retrofitting system. Furthermore, we show that using a structured internal subroutine (such as RAGS) for the inner-loop of the bi-level problem greatly increases the efficiency of the retrofitting system.
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Farley, Ben. "Optimal sensor placement for detection and location of leak/burst events". Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541990.
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Delport, Sven. "The optimal patient-specific placement of the reverse total shoulder component". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97141.
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Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Reverse total shoulder arthroplasty is used as the treatment for arthritic rotator cuff deficient shoulders. Some of the most common complications of a reverse shoulder arthroplasty are scapular notching, glenoid dissociations, glenohumeral dislocation, loosening or dissociation of the humeral component and nerve injury. Clinical outcomes are dependent on the preoperative diagnosis, the function of the deltoid and remaining rotator cuff muscles, biomechanical design of the prosthesis, and the orientation and placement of the reverse shoulder component. This study aims to optimize the patient-specific placement of a reverse shoulder component. A simulation software package was developed that can be used to determine the optimal placement of the reverse shoulder prosthesis for a specific patient. This is achieved by maximizing the humerothoracic range of motion and minimizing the adduction deficit. The motion of the simulation model is driven by shoulder complex motion equations adjusted for each patient. This data was obtained from literature with the motion of the arm fixed to the coronal, scapular and sagittal elevation planes. The influence of the various components of the Tornier Aequalis® - Reversed II system, together with changing the glenoid component inclination and humeral component retroversion, was investigated. This allowed the simulation software to be verified and validated, as well as applying the insight and knowledge gained to a case study. Further simulations evaluated a design change of the humeral component neck-shaft angle from the standard 155 ° to 145 ° or 165 °. The reverse shoulder simulation software provides accurate patient-specific Three Dimensional (3D) pre-operative planning and shoulder complex motion simulation.
AFRIKAANSE OPSOMMING: Omgekeerde volledige skouerartoplastie word as behandeling van ontsteking in gewrigsomhulsel-aangetaste skouers gebruik. Onder die algemeenste komplikasies van 'n omgekeerde skouergewrig-operasie is kepe in die skouerblad (skapulier), lostrekkings of onthegting van die gewrigskom (glenoïede), ontwrigting van die boarm/skouergewrig, die loskom of onthegting van die boarmbeen en beskadiging van senuwees. Mediese resultate is afhanklik van diagnose voor die operasie, die werking van die driehoekspier (deltoïede) en oorblywende draaispiere, die biomeganiese ontwerp van die prostese en die oriëntasie en plasing van die omgekeerde skouerkomponent. Hierdie studie is gemik op die beste pasiënt-spesifieke plasing van die omgekeerde skouerkomponent. Die simulasie-sagtewarepakket wat ontwikkel is, kan gebruik word om die optimale plasing van die omgekeerde skouerprostese in die geval van 'n spesifieke pasiënt te bepaal. Dit word gedoen deur die bewegingsvermoë van die bo-armbeen te maksimaliseer en die gebrekkige werking van die trekspiere te minimaliseer. Die werking van die simulasiemodel word gedryf deur die beweging van skouerkomponente te vergelyk, aangepas vir elke pasiënt. Hierdie data is verkry uit literatuur en die koppeling van die arm se beweging aan die belangrikste, skouerblad- en sagittale elevasievlakke. Die invloed van die onderskeie komponente van die Tornier Aequalis® - Reversed II-stelsel is saam met die verandering van die gewrigskom-komponent se helling en bo-armkomponent se terugstoting ondersoek. Sodoende kon die simulasie-sagteware nagegaan, bevestig en geldig verklaar word; en die insig en kennis wat verkry is op 'n gevallestudie toegepas word. Met verdere simulasies is 'n ontwerpwysiging ge- ëvalueer waar die skouerkomponent se beenpyphoek vanaf die standaard van 155° na 145° of 165° verander is. Die omgekeerde skouersimulasiesagteware maak akkurate pasiëntspesifieke driedimensionele (3D) beplanning voor 'n operasie en simulasie van die bewegings skouerdele moontlik.
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Hertzberg, Samuel y Daniel Dahlgren. "Optimal Placement of a Charging Station for a Robotic Vacuum Cleaner". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229763.
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Robot vacuum cleaners are used in many domestic and industrial appliances around the world today. The vacuum cleaners have a certain goal: To clean an area in a set amount of time. It does so by applying different techniques based on information from its different sensors.However, the efficiency might vary from robot to robot. The variations are a product of many things as the problem is fairly complex.This paper will measure the variations due to point of entry. In a statistical analysis on a simulated dataset results showed that point of entry does affect the robot vacuum cleaner in some cases. Of the two algorithms simulated in this paper, the random bump algorithm showed little to no benefit at all. Whereas the spiral algorithm showed up to a 20% increase in efficiency due to point of entry.Robotdammsugare används i många hushåll och industriella tillämpningar runt om i värden idag. Robotdammsugare har ett visst mål: att städa en yta inom en viss tid. Den gör det genom att använda olika tekniker beroende på informationen det får från sina sensorer. Dock kan effektiviteten variera mellan robot och robot. Variationerna beror på många olika saker då problemet är komplext. Denna rapport kommer att mäta variationer som uppstår på grund av startposition. I en statistisk analys på ett genererat dataset visade resultaten att i några fall påverkar startpositionen robotdammsugaren. Med en av de två algoritmerna som simulerades i detta arbete, random bump algoritmen, visade det sig inte spela stor roll. Medans den andra algoritmen, spiralalgoritmen, kunde bli upp till 20% mer effektiv på grund av startposi-tionen.
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Cuan, Durón Enrique. "Contribution à l'étude du placement optimal de taches de robots redondants". Poitiers, 2008. http://theses.edel.univ-poitiers.fr/theses/2008/Cuan-Duron-Enrique/2008-Cuan-Duron-Enrique-These.pdf.
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Les études menées dans cette thèse concernent le problème du placement optimal de tâches des robots redondants en vue d’améliorer leurs performances cinéstotatiques lors de l’exécution des tâches. Nous rappelons les concepts de la cinématique des manipulateurs ainsi que les notions de redondance et d’accessibilité. Nous examinons aussi les indices de performance cinématique proposés. Ensuite, nous évoquons les contributions existantes, sur le sujet du placement optimal robot / tâche. Ces travaux sont recensés selon trois groupes : ceux concernant l’accessibilité aux tâches; ceux consacrés à l’optimisation des performances cinétostatiques; et ceux envisageant la minimisation du temps du cycle. En tenant compte des limitations des méthodes publiées, nous résolvons le placement de tâches sous trois scénarios : optimisation d’un seul critère de performance pour un point de la tâche dans un environnement sans obstacles ; optimisation multicritère pour plusieurs points de la tâche dans un environnement sans obstacles ; et finalement optimisation globale d’un critère dans un environnement encombré. Nos méthodes constituent des contributions dans le domaine de la planification des mouvements des robots redondants. La prise en compte des contraintes assure l’obtention de solutions réalistes. Nous retenons deux aspects spécifiques de nos méthodes : le premier relatif à la démarche utilisée pour la synthèse de trajectoires articulaires continues entre les points-tâche dans le cas de l’optimisation multicritère ; le second relatif à la fonction objective que nous proposons dans le cas de la méthode avec contrainte anti-collisions. L’efficacité de nos méthodes est validée en les appliquant à des cas divers dans tous les scénarios envisagésThis thesis deals with the placement problem of tasks of redundant robotic manipulators in order to optimize the kinetostatic performances of the robots. The first part of the work addresses a review of the basic concepts of kinematics of manipulators and indices of kinetostatic performances. Then, an analysis is carried out of the proposed methods to solve the optimal placement problem. Three kinds of methods have been identified; they consider the following problems: tasks accessibility ; the optimization of kinetostatic performances; the minimization of cycle-time of tasks. The limitations observed in these works are taken into account in order to propose more efficient methods to compute the optimal placement robot / task. Three scenarios are considered in our work: the optimization of one index of performance for one task-point without obstacles in the environment; a multi-criteria optimization of performances for a number of task-points without obstacles in the environment; and finally, a global optimization of one index of performance taking into account the obstacle avoidance. Thanks to their features, our methods represent an interesting contribution in the area of motion planning of robotic manipulators. Namely, they take into account constraints in order to obtain realistic solutions including obstacle avoidance; on the other hand, the multi-criteria method uses an original algorithm in order to synthesize continuous joint trajectories respecting a prescribed law of motion. According to the knowledge of the author, there are no methods for task placement based on multi-criteria optimization neither by taking into account obstacle avoidance. The efficacy of the proposed methods is illustrated by considering several cases of study
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Shakya, Rosish. "Optimal Placement of Video Caching Routers for Minimization of Retransmission Delay". University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1306429551.
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Pitamber, Neemesh. "The optimal placement of switching devices on rural medium-voltage systems". Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5126.
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Bibliography: leaves 104-106.Electricity is supplied to rural areas by radial networks operating for example at 11 or 22 kV. A problem with radial networks is that faults on the feeders result in the loss of electricity supply to all customers if they are not sectionalised. Some radial networks emanating from one feeder from the sub-station may consist of up to 300 km of line, taking into account spurs, which makes fault detection difficult and increases customer outage time. Protective devices such as reclosers, sectionalisers and fuses are place on distribution systems to reduce the number of customers that will not have service at one time or another due to any fault on the system. There do not appear to be clear rules with regard to the placement of these protective devices. With the installed cost of devices such as sectionalisers bieng over fifty thousand rand, this is naturally of concern to a power utility.
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Aussaguès, Christophe. "Placement optimal de taches pour les systemes paralleles temps-reel critiques". Aix-Marseille 2, 1998. http://www.theses.fr/1998AIX22100.
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Cette these traite de la conception correcte des systemes paralleles temps critiques. Ils constituent une composante essentielle des systemes informatiques de hautes performances de controle-commande que l'on trouve par exemple dans le nucleaire et plus generalement dans les systemes paralleles enfouis. La verification des proprietes de correction temporelle de ces systemes est au cur des travaux de cette these. Notre contribution peut se caracteriser en trois points : l'analyse et l'extension d'un modele de programmation associe a cette classe de systemes la proposition d'une methode de resolution originale fondee sur un nouvel operateur de produit synchronise la validation de cette approche par son implementation et evaluation les travaux presentes concernent en particulier le probleme majeur du placement optimal des processus paralleles suivant des strategies respectant en priorite les contraintes temporelles imposees, i. E. Respectant la ponctualite. La recherche des criteres d'optimalite comporte egalement des parametres specifiques lorsqu'on veut dimensionner l'architecture cible en tenant compte de contraintes operationnelles. Notre approche repose sur l'analyse de la faisabilite, avant execution, de l'ordonnancement dynamique des taches guide par les echeances, suppose exister sur chaque processeur. Cela a conduit a definir l'operateur de produit synchronise des graphes d'etat des taches pour caracteriser leur execution simultanee. A partir du graphe du produit synchronise est engendre automatiquement un systeme de contraintes permettant de calculer une charge maximale des taches sur un processeur et de verifier analytiquement la ponctualite. Les communications, la verification de leur ponctualite et leur integration au probleme de placement constituent la deuxieme contribution de cette these. Enfin, l'algorithme de resolution global integrant l'allocation des taches et des communications a ete mis en uvre et evalue dans le cadre du projet oasis du cea/saclay.
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Telep, David A. "Investigation into optimal Rh(III) dopant placement in silver bromide emulsions /". Online version of thesis, 1993. http://hdl.handle.net/1850/11745.
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Lall, Shruti. "Optimal placement and power allocation for jammers in wireless mesh networks". Diss., University of Pretoria, 2015. http://hdl.handle.net/2263/56082.
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Wireless networks are gaining widespread use and popularity because of their progressive
increase in affordability and convenience. Owing to the improved facilitation of communication
and data transfer, wireless networks are being deployed in numerous modalities, ranging
from wireless local area networks, to mesh and sensor networks. Wireless Mesh Networks
(WMNs) have numerous applications in both civilian and military based environments. The
main disadvantage of WMNs is its susceptibility to interference and eavesdroppers that are
able to intercept, and listen in on the communication between devices in the networks. Eavesdroppers
can act as non-lethal weapons to combatants at war and can have dire consequences
if vital information is obtained by the adversaries. As a result of the emerging and prevalent
use of WMNs in military domains, protecting information contained in networks is of utmost
importance in this information driven age.
This study proposes a novel physical-layer based security method that utilises jammers to
generate additional interference for devices that are eavesdropping on wireless network communication.
The most popular method for ensuring data confidentiality is through the use
of cryptographic techniques; however, as a result of the decentralised nature and power limited
network nodes of WMNs, the protection scheme precludes the use of any cryptographic
techniques and is only physical-layer based. The scheme involves the intelligent placement of continuous jammers in order to achieve maximum protection and data confidentiality for
WMNs with multiple eavesdroppers, sources and destinations. Furthermore, the scheme is
optimised in terms of the transmitting power associated with each jammer, so that the energy
expended by the jammers is kept at a minimum.
The security method is modelled as a minimisation mixed integer non-linear problem, and is
approximated as the sequential solution of two linear optimisation sub-problems relating to
the placement, and power allocation of the wireless jammers. The proposed security model
is subject to constraints which ensure that sufficient interference is generated for malicious
devices that seek to obtain confidential information, while legitimate communication within
the network is not affected. The placement of the jammers takes the form of a multiple
demand multi-dimensional knapsack problem with a minimisation objective. The power
allocation problem is modelled as a linear real-valued minimisation optimisation problem.
The branch-and-cut method, and the simplex method are the algorithms used for solving the
placement and power allocation problems respectively. In the effort to reduce the computation
time associated with solving the linear integer jammer placement problem, an alternating
control tree based heuristic is also developed. The performance of the proposed security
method and heuristic are evaluated through appropriate simulations conducted on random
network instances.
The performance of the proposed security scheme is shown for a number of different scenarios
with varying parameters. The branch-and-cut algorithm is used to solve various cases of the
jammer placement sub-problem while altering parameters such as the grid size, the number
of legitimate nodes, the number of malicious eavesdropping nodes and the locations of potential
jammers. The heuristic is successfully applied to large networks, demonstrating the
scalability of the implementation. The performance in terms of the solution provided and the
computation time associated with use of the heuristic, in comparison to the branch-and-cut
algorithm, is also shown. The heuristic can perform up to 60 times faster than the branchand-
cut method depending on the particular network instance, while returning a solution
that is within 10% of the optimal solution. The use of the heuristic proves to be imperative
in real-life large network scenarios, where an acceptable solution needs to be obtained with
a low execution time. It can therefore be concluded, that for small network scenarios, where
optimality in terms of the number of jamming devices required to protect an area is critical,
the branch-and-cut method should be implemented. However, in scenarios where the execution time is critical, the heuristic can be used to obtain a reasonable solution within a small
time limit.Dissertation (MEng)--University of Pretoria, 2015.
tm2016
Electrical, Electronic and Computer Engineering
MEng
Unrestricted
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Anthony, David Keith. "Robust optimal design using passive and active methods of vibration control". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312863.
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Achanta, Hema Kumari. "Optimal sensing matrices". Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1421.
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Location information is of extreme importance in every walk of life ranging from commercial applications such as location based advertising and location aware next generation communication networks such as the 5G networks to security based applications like threat localization and E-911 calling. In indoor and dense urban environments plagued by multipath effects there is usually a Non Line of Sight (NLOS) scenario preventing GPS based localization. Wireless localization using sensor networks provides a cost effective and accurate solution to the wireless source localization problem. Certain sensor geometries show significantly poor performance even in low noise scenarios when triangulation based localization methods are used. This brings the need for the design of an optimum sensor placement scheme for better performance in the source localization process.
The optimum sensor placement is the one that optimizes the underlying Fisher Information Matrix(FIM) . This thesis will present a class of canonical optimum sensor placements that produce the optimum FIM for N-dimensional source localization N greater than or equal to 2 for a case where the source location has a radially symmetric probability density function within a N-dimensional sphere and the sensors are all on or outside the surface of a concentric outer N-dimensional sphere. While the canonical solution that we designed for the 2D problem represents optimum spherical codes, the study of 3 or higher dimensional design provides great insights into the design of measurement matrices with equal norm columns that have the smallest possible condition number. Such matrices are of importance in compressed sensing based applications.
This thesis also presents an optimum sensing matrix design for energy efficient source localization in 2D. Specifically, the results relate to the worst case scenario when the minimum number of sensors are active in the sensor network. We also propose a distributed control law that guides the motion of the sensors on the circumference of the outer circle so that achieve the optimum sensor placement with minimum communication overhead.
The design of equal norm column sensing matrices has a variety of other applications apart from the optimum sensor placement for N-dimensional source localization. One such application is fourier analysis in Magnetic Resonance Imaging (MRI). Depending on the method used to acquire the MR image, one can choose an appropriate transform domain that transforms the MR image into a sparse image that is compressible. Some such transform domains include Wavelet Transform and Fourier Transform. The inherent sparsity of the MR images in an appropriately chosen transform domain, motivates one of the objectives of this thesis which is to provide a method for designing a compressive sensing measurement matrix by choosing a subset of rows from the Discrete Fourier Transform (DFT) matrix. This thesis uses the spark of the matrix as the design criterion. The spark of a matrix is defined as the smallest number of linearly dependent columns of the matrix. The objective is to select a subset of rows from the DFT matrix in order to achieve maximum spark. The design procedure leads us to an interest study of coprime conditions on the row indices chosen with the size of the DFT matrix.
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Ding, Qifeng. "Optimal meter placement and transaction-based loss allocation in deregulated power system operation". Texas A&M University, 2004. http://hdl.handle.net/1969.1/1475.
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In this dissertation topics of optimal meter placement and transaction-based loss allocation in deregulated power system operation are investigated.
Firstly, Chapter II introduces the basic idea of candidate measurement identification, which is the selection of candidate measurement sets, each of which will make the system observable under a given contingency (loss of measurements and network topology changes). A new method is then developed for optimal meter placement, which is the choice of the optimal combination out of the selected candidate measurement sets in order to ensure the entire system observability under any one of the contingencies.
A new method, which allows a natural separation of losses among individual transactions in a multiple-transaction setting is proposed in Chapter III. The proposed method does not use any approximations such as a D.C. power flow, avoiding method induced inaccuracies. The power network losses are expressed in terms of individual power transactions. A transaction-loss matrix, which illustrates the breakdown of losses introduced by each individual transaction and interactions between any two transactions, is created. The network losses can then be allocated to each transaction based on the transaction-loss matrix entries.
The conventional power flow analysis is extended in Chapter IV to combine with the transaction loss allocation. A systematic solution procedure is formed in order to adjust generation while simultaneously allocating losses to the generators designated by individual transactions.
Furthermore, Chapter V presents an Optimal Power Flow (OPF) algorithm to optimize the loss compensation if some transactions elect to purchase the loss service from the Independent System Operator (ISO) and accordingly the incurred losses are fairly allocated back to individual transactions. IEEE test systems have been used to verify the effectiveness of the proposed method.
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Gerbex, Stéphane. "Métaheuristiques appliquées au placement optimal de dispositifs FACTS dans un réseau électrique /". [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?nr=2742.
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Bohning, Ryan S. "Optimal placement of non-intrusive waste heat recovery devices in exhaust ducts". Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45816.
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Approved for public release; distribution is unlimitedThe Secretary of the Navy has ordered the U.S. Navy and Marine Corps to reduce energy usage. This study explores how to optimize placement and size of a non-intrusive waste heat recovery device for energy recovery in exhaust ducts. Additionally, it explores the effect that a device has on the exhaust infrared signature by analyzing the change in the bulk temperature at the exhaust outlet. Optimal device placement and size is dependent on duct geometry, external heat transfer coefficient, and flow characteristics, namely Reynolds number. Infrared signature intensity reductions of 1–14% are only achievable with unpractically long thermoelectric generator devices and high external heat transfer coefficients. Doubling the external heat transfer coefficient increases heat recovery by 15–30% for low Reynolds number flows (104) and 75–90% for high Reynolds number flows (105~106). In low Reynolds number flows (~104), device position can account for a 75% change in energy recovery whereas high Reynolds number flows (~106) have unexpected areas of higher heat transfer. Position changes can increase heat recovery 10–70%, while increasing device size may only marginally improve results. Identifying local maxima for heat transfer, especially in high Reynolds number flows (~106), is counterintuitive because of unexpected recirculation zone effects.
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Szczepanski, Robert Walter. "Optimal placement of actuators and sensors for vibration control using genetic algorithms". Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341754.
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RIFFARD, VINCENT. "Accessibilite d'un operateur humain en environnement tres contraint : placement optimal et posture". Nantes, 1995. http://www.theses.fr/1995NANT2103.
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Devant la complexite toujours croissante des ensembles mecaniques, il devient aujourd'hui necessaire de disposer d'outils efficaces d'aide a la conception. Les interventions d'un operateur humain pendant les phases de montage ou de maintenance d'un produit sont particulierement etudiees. La modelisation de l'intervention d'un operateur dans un modele cfao, pose deux types de problemes. Le premier concerne la faisabilite geometrique d'une tache: son accessibilite sous contraintes. Le deuxieme concerne la qualite de la posture adoptee par l'operateur, pour realiser la tache. Les taches d'accessibilite sont decrites par les liaisons mecaniques courantes. Ce formalisme fournit une methode de resolution generique. Une modelisation cinematique de l'operateur est retenue. Les contraintes de non-collision et de verification des limites articulaires sont prises en compte. Enfin, le probleme d'accessibilite a ete represente par une fonction mathematique ou critere, minimisee par un algorithme d'optimisation globale. La resolution de nombreux exemples, dans des environnements tres contraints, a permis de conclure sur la robustesse de notre approche. Dans un deuxieme temps, nous proposons des criteres d'evaluation de la qualite d'une posture, bases sur la description biomecanique de celle-ci. Nous avons notamment pris en compte les couplages articulaires de l'articulation de l'epaule, la qualite de la vision de la tache, les couples articulaires induits par la pesanteur et la tache. Un critere complet permet l'optimisation simultanee de ces criteres, tout en satisfaisant les contraintes initiales du probleme d'accessibilite. L'application de ces criteres a l'etude d'une posture de travail, nous a permis de constater son amelioration notable. Notre travail permet de resoudre de maniere robuste et generique, le probleme de l'accessibilite dans le cas d'une tache de dimension quelconque, tout en ameliorant la qualite de la posture. Il contribue a la prise en compte des operateurs humains, en phase de montage et de maintenance, dans la perspective de la conception integree des produits
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Hitzeroth, Helmuth Victor. "Optimal capacitor placement to minimise harmonics in power systems and software tools". Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/19678.
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Harmonics in power systems is a relatively new area of research. In view of this and the growing awareness of the quality of the electricity supply, the theory of harmonics in power systems is reviewed. The sources and the effects of harmonics are investigated. The algorithms that are used for the frequency analysis of power systems are investigated and compared. These algorithms comprise the companion circuit method, the Gauss-Seidel method, the Newton-Raphson method and the current injection method. In addition various freely and commercially available software packages for the harmonic analysis of power systems are studied and compared. For this purpose a questionnaire was sent out to software developers and suppliers. This questionnaire as well as the results of the comparative investigation are presented. A power system has many configurations due to the switching of power capacitors on to and off the power grid. Some of these configurations can result in unacceptable distortion levels. An existing state space method is investigated to analyse these configurations and an example is worked through, to illustrate how this method works. However, this state space model is only applicable to radial power systems and there have to be power capacitors at the end of every feeder amongst others. Because of these significant disadvantages of this method, a new analytical approach or theoretical foundation for the analysis of power capacitors in radial as well as meshed power systems is developed in this thesis. For this purpose the branch current and nodal voltage equations are determined. Redundant nodal voltages are eliminated from the set of branch current equations. The remaining equations and the nodal voltage equations are then combined to form a system realisation. This system realisation is still overspecified and a further reduction is done to obtain a minimal realisation of the power system. This approach is demonstrated analytically and numerically by way of five case studies. This approach is also verified by comparing it with the current injection method. Identical results are obtained with the state space approach and with the current injection method, demonstrating that the state space approach is indeed valid.
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Fish, Adbul-Aziz. "Optimal placement of phasor measurement units using the Advanced Matrix Manipulation algorithm". Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/5223.
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Includes abstract.Includes bibliographical references.
This thesis investigates the problem of the Optimal Placement scheme of Phasor Measurement Units in electrical power systems for State Estimation to facilitate improved monitoring and control of the system parameters. The research work done for this thesis begins with review of Supervisory Control and Data Acquisition systems (SCADA). SCADA-based systems are currently employed for condition monitoring and control of industrial and utility electrical power systems. For utility power networks, the main problem with voltage and current phasor data captured by SCADA systems is that they are not synchronised with respect to each other in a present-time or Real-time framework. This implies that both magnitude and phase angle of the measured phasors tend to get affected by slow data flow provided by SCADA to the points of utilization and also by differences in time instants of data capture. These factors inhibit theefficiency and quality of the power system monitoring and control. “Phasor Measurement Unit” (PMU) is a relatively new technology that, when employed in power networks, offers real-time synchronised measurements of the voltages at buses and currents along the lines that connect them. This is accomplished by using a GPS based monitoring system which facilitates time synchronisation of measurements and unlike SCADA, makes the measured data available in Real-Time format. SCADA is not able to provide Real-time data due to the low speeds at which RTUs (Remote Terminal Units) provide data. Availability of time-stamped phasor measurements makes PMUs preferable for power system monitoring and control applications such as State Estimation, Instability Prediction Analysis, Real-time Monitoring of the system conditions, Islanding Detection, System Restoration and Bad Data Detection.
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Yu-HsuanLin y 林郁軒. "Optimal Placement of Electronic Packages". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/97762327522457686342.
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碩士國立成功大學
航空太空工程學系碩博士班
98
Since the tests of electronic packages usually require a large amount of time and resource, computer simulation is usually considered instead of traditional tests. However, due to the complexity of the structure in electronic packages, highly-efficient computers are needed, but this doesn’t ensure the quality of analysis and may increase the cost. In order to avoid unnecessary efforts on analyzing, and to improve the result, equivalent moduli and optimization method are chosen to shorten the time spent on analysis and increase the efficiency in this research. The concept of equivalent moduli is to homogenize those composite materials with complicated properties into effective homogeneous material with simpler mechanical properties, and therefore to reduce the amount of time for analysis. Besides, a correction method is also proposed to strengthen the correctness of the effective material properties, and by artificial neural network the calculation of stress intensity factor (SIF) is also integrated. Utilizing the optimization method, we may find the optimal placement for the components on the package.