Дисертації з теми "Energy-Constrained"
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1
Wang, Xun. "On constrained contour energy minimization." Cincinnati, Ohio : University of Cincinnati, 2004. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1106795223.
2
Tsimbalo, Evgeny. "Energy-constrained wireless communications for IoT." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723512.
3
Karousatou, Christina. "Distributed algorithms for energy constrained mobile agents." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0373/document.
Анотація:
Dans cette thèse, nous étudions et concevons des algorithmes pour des agents mobiles se déplaçant dans un graphe avec une énergie limité, restreignant leurs mouvements. Chaque agent mobile est une entité, équipée d’une batterie, qui peut parcourir les arêtes du graphe et visiter les noeuds du graphe. A chaque mouvement, l’agent consomme une partie de son énergie. Contrairement à divers modèles bien étudiés pour les agents mobiles, très peu de recherches ont été menées pour le modèle compte tenu des limites d’énergie. Nous étudions les problèmes fondamentaux de l’exploration d’un graphe, du gathering et du collaborative delivery dans ce modèleIn this thesis we study and design algorithms for solving various well-known problems for mobile agents moving on a graph, with the additional constraint of limited energy which restricts the movement of the agents. Each mobile agent is an entity, equipped with a battery, that can traverse the edges of the graph and visit the nodes of the graph, consuming a part of its energy for movement. In contrast to various well-studied models for mobile agents, very little research has been conducted for the model considering the energy limitations. We study the fundamental problems of graph exploration, gathering and collaborative delivery in this model
4
Van, Ackooij Wim. "Chance Constrained Programming : with applications in Energy Management." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2013. http://www.theses.fr/2013ECAP0071/document.
Анотація:
Les contraintes en probabilité constituent un modèle pertinent pour gérer les incertitudes dans les problèmes de décision. En management d’énergie de nombreux problèmes d’optimisation ont des incertitudes sous-jacentes. En particulier c’est le cas des problèmes de gestion de la production au court-terme. Dans cette Thèse, nous investiguons les contraintes probabilistes sous l’angle théorique, algorithmique et applicative. Nous donnons quelques nouveaux résultats de différentiabilité des contraintes en probabilité et de convexité des ensembles admissibles. Des nouvelles variantes des méthodes de faisceaux « proximales » et « de niveaux » sont spécialement mises au point pour traiter des problèmes d’optimisation convexe sous contrainte en probabilité. Ces algorithmes gèrent en particulier, les erreurs d’évaluation de la contrainte en probabilité, ainsi que son gradient. La convergence vers une solution du problème est montrée. Enfin, nous examinons deux applications : l’optimisation d’une vallée hydraulique sous incertitude sur les apports et l’optimisation d’un planning de production sous incertitude sur la demande. Dans les deux cas nous utilisons une contrainte en probabilité pour gérer les incertitudes. Les résultats numériques présentés semblent montrer la faisabilité de résoudre des problèmes d’optimisation avec une contrainte en probabilité jointe portant sur un système de environ 200 contraintes. Il s’agit de l’ordre de grandeur nécessaire pour les applications. Les nouveaux résultats de différentiabilité concernent à la fois des contraintes en probabilité portant sur des systèmes linéaires et non-linéaires. Dans le deuxième cas, la convexité dans l’argument représentant le vecteur incertain est requise. Ce vecteur est supposé suivre une loi Gaussienne ou Student multi-variée. Les formules de gradient permettent l’application directe d’un schéma d’évaluation numérique efficient. Pour les contraintes en probabilité qui peuvent se réécrire à l’aide d’une Copule, nous donnons de nouveau résultats de convexité pour l’ensemble admissibles. Ces résultats requirent la concavité généralisée de la Copule, les distributions marginales sous-jacents et du système d’incertitude. Il est suffisant que ces propriétés de concavité généralisée tiennent sur un ensemble spécifiqueIn optimization problems involving uncertainty, probabilistic constraints are an important tool for defining safety of decisions. In Energy management, many optimization problems have some underlying uncertainty. In particular this is the case of unit commitment problems. In this Thesis, we will investigate probabilistic constraints from a theoretical, algorithmic and applicative point of view. We provide new insights on differentiability of probabilistic constraints and on convexity results of feasible sets. New variants of bundle methods, both of proximal and level type, specially tailored for convex optimization under probabilistic constraints, are given and convergence shown. Both methods explicitly deal with evaluation errors in both the gradient and value of the probabilistic constraint. We also look at two applications from energy management: cascaded reservoir management with uncertainty on inflows and unit commitment with uncertainty on customer load. In both applications uncertainty is dealt with through the use of probabilistic constraints. The presented numerical results seem to indicate the feasibility of solving an optimization problem with a joint probabilistic constraint on a system having up to 200 constraints. This is roughly the order of magnitude needed in the applications. The differentiability results involve probabilistic constraints on uncertain linear and nonlinear inequality systems. In the latter case a convexity structure in the underlying uncertainty vector is required. The uncertainty vector is assumed to have a multivariate Gaussian or Student law. The provided gradient formulae allow for efficient numerical sampling schemes. For probabilistic constraints that can be rewritten through the use of Copulae, we provide new insights on convexity of the feasible set. These results require a generalized concavity structure of the Copulae, the marginal distribution functions of the underlying random vector and of the underlying inequality system. These generalized concavity properties may hold only on specific sets
5
Margi, Cíntia Borges. "Energy consumption trade-offs in power constrained networks /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
6
Van, ackooij Wim Stefanus. "Chance Constrained Programming : with applications in Energy Management." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00978519.
Анотація:
In optimization problems involving uncertainty, probabilistic constraints are an important tool for defining safety of decisions. In Energy management, many optimization problems have some underlying uncertainty. In particular this is the case of unit commitment problems. In this Thesis, we will investigate probabilistic constraints from a theoretical, algorithmic and applicative point of view. We provide new insights on differentiability of probabilistic constraints and on convexity results of feasible sets. New variants of bundle methods, both of proximal and level type, specially tailored for convex optimization under probabilistic constraints, are given and convergence shown. Both methods explicitly deal with evaluation errors in both the gradient and value of the probabilistic constraint. We also look at two applications from energy management: cascaded reservoir management with uncertainty on inflows and unit commitment with uncertainty on customer load. In both applications uncertainty is dealt with through the use of probabilistic constraints. The presented numerical results seem to indicate the feasibility of solving an optimization problem with a joint probabilistic constraint on a system having up to 200 constraints. This is roughly the order of magnitude needed in the applications. The differentiability results involve probabilistic constraints on uncertain linear and nonlinear inequality systems. In the latter case a convexity structure in the underlying uncertainty vector is required. The uncertainty vector is assumed to have a multivariate Gaussian or Student law. The provided gradient formulae allow for efficient numerical sampling schemes. For probabilistic constraints that can be rewritten through the use of Copulae, we provide new insights on convexity of the feasible set. These results require a generalized concavity structure of the Copulae, the marginal distribution functions of the underlying random vector and of the underlying inequality system. These generalized concavity properties may hold only on specific sets.
7
Du, Hongtao. "Energy-constrained microsensor platform on-board image processing." Saarbrücken VDM Verlag Dr. Müller, 2007. http://d-nb.info/985423781/04.
8
Ramachandran, Iyappan. "Joint PHY-MAC optimization for energy-constrained wireless networks /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5968.
9
Hendijanizadeh, M. "Design and optimisation of constrained electromagnetic energy harvesting devices." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/364524/.
Анотація:
This thesis investigates the design and optimisation of constrained electromagnetic energy harvesters. It provides optimal design guidelines for constrained electromagnetic energy harvesters under harmonic and random vibrations. To find the characteristics of the vibration source, for instance vertical motion of a boat, the spectrum of the excitation amplitude should be obtained. Two Kalman filter based methods are proposed to overcome the difficulties of calculating displacement from measured acceleration. Analytical models describing the dynamics of linear and rotational electromagnetic energy harvesters are developed. These models are used to formulate a set of design rules for constrained linear and rotational energy harvesters subjected to a given sinusoidal excitation. For the sake of comparison and based on the electromechanical coupling coefficient of the systems, the maximum output power and the corresponding efficiency of linear and rotational harvesters are derived in a unified form. It is shown that under certain condition, rotational systems have greater capabilities in transferring energy to the load resistance and hence obtaining higher efficiency than linear systems. Also, the performance of a designed rotational harvester in response to broadband and band-limited random vibrations is evaluated and an optimum design process is presented for maximizing the output power under these conditions. It is furthermore shown that the profile of the spectral density of the measured acceleration signal of a typical boat can be approximated by a Cauchy distribution which is used to calculate the extracted power extracted by the proposed energy harvester in real conditions. In order to increase the operational bandwidth of rotational energy harvesters, subjected to time-varying frequency vibrations, a variable moment of inertia mechanism is proposed to adaptively tune the resonance frequency of harvester to match the excitation frequency. Also, the effects of combining the variable moment of inertia mechanism and adjusting the load resistance to increase the operational bandwidth of the system for constrained and unconstrained applications are studied. Finally, a ball screw based prototype is manufactured and the experimental results of its testing are presented which confirm the validity of the design and the derived dynamic equations of the system.
10
Nguyen, Tuan-Duc. "Cooperative MIMO strategies for energy constrained wireless sensor networks." Rennes 1, 2009. https://theses.hal.science/docs/00/44/58/14/PDF/nguyen09PhDthesis_Cooperative_MIMO_Strategies_for_Energy_constrained_Wireless_Sensor_Networks.pdf.
Анотація:
In wireless distributed networks, where multiple antennas can not be integrated in one node, cooperative Multi-Input Multi-Output (MIMO) techniques help to exploit the space time diversity gain in order to increase performances or to reduce the transmission energy consumption. In this thesis, strategies using cooperative MIMO techniques are proposed for Wireless Sensor Network (WSN) where the energy consumption is the most important design criterion. The performance and the energy consumption advantages of cooperative MIMO technique are investigated, in comparison with the SISO, multi-hop SISO and cooperative Relay techniques, and an optimal selection of transmit-receive antennas number in terms of energy consumption is also proposed as a function of transmission distances. Since the wireless nodes are physically separated in cooperative MIMO systems, the imperfect time synchronization between cooperative nodes clocks leads to an unsynchronized MIMO transmission. The performance degradation of this cooperative transmission synchronization error and the cooperative reception additional noise is evaluated by simulations. Two new cooperative reception techniques based on the relay principle and a new efficient space-time combination technique are proposed in order to increase the energy efficiency of cooperative MIMO systems. Finally, performance and energy consumption comparisons between cooperative MIMO and Relay techniques are performed and an association strategy is also proposed to exploit simultaneously the advantages of the two cooperative techniquesDans les réseaux sans fil distribués où plusieurs antennes ne peuvent pas être intégrées dans un même nœud de communication, les techniques MIMO (Multiple Input Multiple Output) coopératives permettent d'exploiter le gain de la diversité spatio-temporelle pour augmenter les performances ou réduire l'énergie consommée pour les communications. Dans cette thèse, des stratégies MIMO coopératives sont proposées pour les réseaux de capteurs sans fil (RCS), où la consommation d'énergie est la contrainte la plus importante. Leur avantage en termes de taux d'erreur et de consommation d'énergie sur les techniques mono-antenne (SISO), même multi-étapes, et sur les techniques de relais, est clairement mis en évidence. Une sélection du nombre d'antennes d'émission et de réception, optimale en termes d'efficacité énergétique, est également proposée en fonction des distances de transmission. Les inconvénients du MIMO coopératif, comme les imperfections de synchronisation à l'émission ou les bruits additifs en réception, qui affectent leurs performances dans les réseaux sans fil distribués, sont abordés. Deux nouvelles techniques de réception coopérative basées sur le principe de relais, ainsi qu'une nouvelle technique de combinaison spatio-temporelle sont proposées afin d'augmenter l'efficacité énergique de ces systèmes MIMO coopératifs. Enfin, des comparaisons de performance et de consommation d'énergie entre les techniques MIMO coopératives et de relais montrent que leur utilisation dépend beaucoup de la topologie du réseau et de l'application. Une stratégie d'association est proposée pour exploiter simultanément les avantages des deux techniques de coopération
11
Krogsveen, Even. "Energy-Efficient Link Adaptation and Resource Allocation in Energy-Constrained Wireless Ad Hoc Networks." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8762.
Анотація:
Wireless ad hoc networks have a number of advantages over traditional, infrastructure-based networks. Robustness and easy deployment are two of the main advantages. However, the distributed nature of such networks raises a number of design challenges, especially when energy-efficiency and QoS requirements are to be taken into consideration. These challenges can only be met by allowing closer cooperation and mutual adaptation between the protocol layers, referred to as a cross-layer design paradigm. In energy-constrained wireless ad hoc networks, each node can only transmit to a limited number of other nodes directly. Hence, in order to reach distant destinations, intermediate nodes must relay the traffic of their peer nodes, resulting in multihop routes. The total energy consumption associated with a end-to-end transmission over such a route can be significantly reduced if the nodes are correctly configured. A cross-layer, optimization scheme, based on adaptive modulation and power control, is proposed in this thesis. The optimization scheme assumes that an existing route has been found, and allows QoS requirements in terms of end-to-end bit error rate and delay. Both transmission and circuit energy consumption is taken into consideration. By jointly optimizing all nodes throughout the route, the total energy consumption can be reduced by more than 50%, compared to a fixed-rate system. The adaptive system also exhibits superior capabilities to meet stringent QoS requirements. Results for both continuous and discrete rate adaptation is produced, and it is found that discrete adaptation causes only a small performance degradation, compared to the optimal, continuous case. Simulations also show that the system is vulnerable to inaccurate link state information. Finally, the effects of maximum-rate limitation and ignoring the circuit power consumption is investigated.
12
Björnemo, Erik. "Energy Constrained Wireless Sensor Networks : Communication Principles and Sensing Aspects." Doctoral thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9519.
Анотація:
Wireless sensor networks are attractive largely because they need no wired infrastructure. But precisely this feature makes them energy constrained, and the consequences of this hard energy constraint are the overall topic of this thesis. We are in particular concerned with principles for energy efficient wireless communication and the energy-wise trade-off between sensing and radio communication. Radio transmission between sensors incurs both a fixed energy cost from radio circuit processing, and a variable energy cost related to the level of radiated energy. We here find that transmission techniques that are otherwise considered efficient consumes too much processing energy. Currently available sensor node radios typically have a maximum output power that is too limited to benefit from transmission-efficient, but processing-intensive, techniques. Our results provide new design guidelines for the radio output power. With increasing transmission energy -- with increasing distance -- the considered techniques should be applied in the following order: output power control, polarisation receiver diversity, error correcting codes, multi-hop communication, and cooperative multiple-input multiple-output transmissions. To assess the measurement capability of the network as a whole, and to facilitate a study of the sensing-communication trade-off, we devise a new metric: the network measurement capacity. It is based on the number of different measurement sequences that a network can provide, and is hence a measure of the network's readiness to meet a large number of possible events. Optimised multi-hop routing under this metric reveals that the energy consumed for sensing has decisive impact on the best multi-hop routes. We also find support for the use of hierarchical heterogeneous network structures. Model parameter uncertainties have large impact on our results and we use probability theory as logic to include them consistently. Our analysis shows that common assumptions can give misleading results, and our analysis of radio channel measurements confirms the inadequacy of the Rayleigh fading channel model.wisenet
13
Gebregiorgis, Anteneh [Verfasser], and M. [Akademischer Betreuer] Tahoori. "Resilient Energy-Constrained Microprocessor Architectures / Anteneh Gebregiorgis ; Betreuer: M. Tahoori." Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1186139986/34.
14
TAVARES, Eduardo Antônio Guimarães. "Software Synthesis for Energy-Constrained Hard Real-Time Embedded Systems." Universidade Federal de Pernambuco, 2009. https://repositorio.ufpe.br/handle/123456789/1403.
Анотація:
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Previous issue date: 2009A grande expansão do mercado de dispositivos digitais tem forçado empresas desenvolvedoras de sistemas embarcados em lidar com diversos desafios para prover sistemas complexos nesse nicho de mercado. Um dos desafios prominentes está relacionado ao consumo de energia, principalmente, devido aos seguintes fatores: (i) mobilidade; (ii) problemas ambientais; e (iii) o custo da energia. Como consequência, consideráveis esforços de pesquisa têm sido dedicados para a criação de técnicas voltadas para aumentar a economia de energia. Na última década, diversas técnicas foram desenvolvidas para reduzir o consumo de energia em sistemas embarcados. Muitos métodos lidam com gerenciamento dinâmico de energia (DPM), como, por exemplo, dynamic voltage scaling (DVS), cooperativamente com sistemas operacionais especializados, a fim de controlar o consumo de energia durante a execução do sistema. Entretanto, apesar da disponibilidade de muitos métodos de redução de consumo de energia, diversas questões estão em aberto, principalmente, no contexto de sistemas de tempo real crítico. Este trabalho propõe um método de síntese de software, o qual leva em consideração relação entre tarefas, overheads, restrições temporais e de energia. O método é composto por diversas atividades, as quais incluem: (i) medição; (ii) especificação; (iii) modelagem formal; (vi) escalonamento; e (v) geração de código. O método também é centrado no formalismo redes de Petri, o qual define uma base para geração precisa de escalas em tempo de projeto, adotando DVS para reduzir o consumo de energia. A partir de uma escala viável, um código customizado é gerado satisfazendo as restrições especificadas, e, dessa forma, garantindo previsibilidade em tempo de execução. Para lidar com a natureza estática das escalas geradas em tempo de projeto, um escalonador simples em tempo de execução é também proposto para melhorar o consumo de energia durante a execução do sistema. Diversos experimentos foram conduzidos, os quais demonstram a viabilidade da abordagem proposta para satisfazer restrições críticas de tempo e energia. Adicionalmente, um conjunto integrado de ferramentas foram desenvolvidas para automatizar algumas atividades do método de síntese de software proposto
15
Kang, Intae. "Topology control for broadcasting over energy constrained wireless ad hoc networks /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6061.
16
Bjørnstad, Eiril. "Control of Wave Energy Converter with constrained electric Power Take Off." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12469.
Анотація:
Because of ocean waves' high energy density and substantial, global technical potential wave energy might become a significant contributor to supply the world's increasing energy demand. The nature of ocean waves is strongly irregular and the power generation from a Wave Energy Converter will have large fluctuations what is a challenge for the electrical system. In the history of wave energy research the focus has been on controlling devices for increasing the absorbed power based on results from mechanical and hydrodynamic mathematical analysis. However, recent work shows that the peak of produced power increases compared to the average absorbed power when traditional control strategies like passive loading and optimal control are applied. The rating and the energy storage requirements of the electrical system will then be increased and the gain due to the increased power production might be lost.In recent work a control strategy that optimizes the torque of the generator with respect to a power saturation level is presented. The work in this report focuses on a practical implementation of this strategy. Further, modifications to meet the torque and speed limitations of the system are made. A control algorithm is presented that utilizes the overrated speed region of the generator to maximize the power production with regards to the power and torque ratings. Simulations for irregular waves and control parameters chosen according to passive loading are then executed and the control algorithm is realized by use of field oriented control of the induction generator. The average absorbed power is changed only to moderate extends compared to the unconstrained case. At the same time the peak to average ratio and the maximum torque is considerably reduced. However, the strategy's reduced torque capability results in a higher maximum speed and pull out speed can be reached. Consequently there will be a trade off between investment costs, produced power and operation range of the system. Therefore the system should be optimized with respect to torque and power limitations, costs, produced power and pullout speed.
17
Harjula, E. (Erkki). "Energy-efficient peer-to-peer networking for constrained-capacity mobile environments." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212494.
Анотація:
Abstract Energy efficiency is a powerful measure for promoting sustainability in technological evolution and ensuring feasible battery life of end-user devices in mobile computing. Peer-to-peer technology provides decentralized and self-organizing architecture for distributing content between devices in networks that scale up almost infinitely. However, peer-to-peer networking may require lots of resources from peer nodes, which in turn may lead to increased energy consumption on mobile devices. For this reason, peer-to-peer networking has so far been considered unfeasible for mobile environment. This thesis makes several contributions towards enabling energy-aware peer-to-peer networking in mobile environments. First, an empirical study is conducted to understand the energy consumption characteristics of radio interfaces and typical composition of traffic in structured peer-to-peer networks. This is done in order to identify the most essential obstacles for utilizing peer-to-peer technology in mobile environments. Second, the e-Aware model for estimating the energy consumption of a mobile device is developed and empirically verified to achieve 3-21% error in comparison to real-life measurements. Third, the e-Mon model for the energy-aware load monitoring of peer nodes is developed and demonstrated to improve the battery life of mobile peer nodes up to 470%. Fourth, the ADHT concept of mobile agent based virtual peers is proposed for sharing the peer responsibilities between peer nodes in a subnet so that they can participate in a peer-to-peer overlay without compromising their battery life. The results give valuable insight into implementing energy-efficient peer-to-peer systems in mobile environments. The e-Aware energy consumption model accelerates the development of energy-efficient networking solutions by reducing the need for time-consuming iterations between system development and evaluations with real-life networks and devices. The e-Mon load monitoring model facilitates the participation of battery-powered devices in peer-to-peer and other distributed networks by enabling energy-aware load balancing where energy-critical mobile nodes carry less load than other nodes. The ADHT facilitates the participation of constrained-capacity wireless devices, such as machine-to-machine nodes, in a peer-to-peer network by allowing them to sleep for most of their timeTiivistelmä Energiatehokkuus on kustannustehokas tapa vähentää päätelaitteiden käytön aiheuttamia kasvihuonepäästöjä sekä parantaa niiden akunkestoa. Vertaisverkkoteknologia tarjoaa hajautetun, itseorganisoituvan, sekä lähes rajattomasti skaalautuvan verkkoarkkitehtuurin päätelaitteiden väliseen tallennustilan, mediasisältöjen ja tietoliikennekapasiteetin suorajakamiseen. Vertaisverkkojen suurin heikkous mobiilikäytön näkökulmasta on niiden päätelaitteille aiheuttama ylimääräinen kuormitus, mikä näkyy lisääntyneenä energiankulutuksena. Tässä väitöskirjassa on tutkittu mekanismeja vertaisverkon päätelaitteiden energiatehokkuuden parantamiseksi, tavoitteena riittävä akunkesto mobiilikäytössä. Aluksi työssä tutkittiin empiirisesti langattomien verkkojen mobiilipäätelaitteille aiheuttamaa energiankulutusta sekä rakenteellisten vertaisverkkojen vertaispäätelaitteille aiheuttamaa liikennekuormitusta. Tavoitteena oli muodostaa käsitys suurimmista haasteista mobiililaitteiden käytölle vertaisverkoissa. Seuraavaksi mobiiliverkkojen energiankulutusta koskevasta havaintoaineistosta muodostettiin energiankulutusmalli, e-Aware, jolla voitiin arvioida mobiilipäätelaitteen energiankulutusta erilaisilla verkon liikenneprofiileilla. Mallilla saavutettiin parhaimmillaan kolmen prosentin keskimääräinen virhe. Kolmannessa vaiheessa kehitettiin energiatietoinen kuormanseurantamalli, e-Mon, jota käyttäen saavutettiin jopa 470 % lisäys mobiilin vertaispäätelaitteen akunkestoon. Viimeisessä vaiheessa kehitettiin ADHT-konsepti, joka on uudentyyppinen tapa jakaa vertaispäätelaitteiden kuormaa usean saman verkkoklusterin päätelaitteen kesken käyttäen laitteesta toiseen kiertävää mobiiliagenttia. Väitöskirjan tulokset osoittavat että mobiililaitteiden energiatehokkuutta vertaisverkoissa pystytään olennaisesti parantamaan energiatietoisia kuormanjakomekanismeja käyttäen. Työssä kehitetty e-Aware nopeuttaa energiatehokkaiden hajautettujen järjestelmien kehitystyötä tarjoamalla tehokkaan työkalun järjestelmän energiankulutuksen arvioimiseen jo kehitysvaiheessa. e-Mon mahdollistaa energiatietoisen kuormanjaon vertaisverkoissa tarjoamalla tarvittavan kuormanseurantamallin. ADHT puolestaan tarjoaa uudenlaisen tavan vähentää vertaisverkkojen aiheuttamaa päätelaitekuormitusta hyödyntäen maksimaalisesti rajoitetun kapasiteetin laitteiden unitilojen käyttöön perustuvaa energiankulutusoptimointia
18
Advani, Nikhil Kamalkumar. "Decentralized Control of an Energy Constrained Heterogeneous Swarm for Persistent Surveillance." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-theses/408.
Анотація:
Robot swarms are envisioned in applications such as surveillance, agriculture, search-and-rescue operations, and construction. The decentralized nature of swarm intelligence has three key advantages over traditional multi-robot control algorithms: it is scalable, it is fault tolerant, and it is not susceptible to a single point of failure. These advantages are critical to the task of persistent surveillance - where a number of target locations need to be visited as frequently as possible. Unfortunately, in the real world, the autonomous robots that can be used for persistent surveillance have a limited battery life (or fuel capacity). Thus, they need to abandon their surveillance duties to visit a battery swapping station (or refueling depot) a.k.a. €˜depots€™. This €˜down time€™ reduces the frequency of visitation. This problem can be eliminated if the depots themselves were autonomous vehicles that could meet the (surveillance) robots at some point along their path from one target to another. Thus, the robots would spend less time on the 'charging' (or refueling) task. In this thesis we present decentralized control algorithms, and their results, for three stages of the persistent surveillance problem. First, we consider the case where the robots have no energy constraints, and use a decentralized approach to allow the robots choose the €˜best€™ target that they should visit next. While the selection process is decentralized, the robots can communicate with all the other robots in the swarm, and let them know which is their chosen target. We then consider the energy constraints of the robots, and slightly modify the algorithm, so that the robots visit a depot before they run out of energy. Lastly, we consider the case where the depots themselves can move, and communicate with the robots to pick a location and time to meet, to be able to swap the empty battery of a robot, with a fresh one. The goal of persistent surveillance is to visit target locations as frequently as possible, and thus, the performance measurement parameter is chosen to be the median frequency of visitation for all target locations. We evaluate the performance of the three algorithms in an extensive set of simulated experiments.
19
Keogh, Bradley. "Performance quantification of marine current energy converters in constrained flow fields." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/393735/.
Анотація:
The Marine Current Energy Converter (MCEC) industry is currently at a stage where early farms are being designed. These farms will provide an indication of the commercial viability of the technology to future investors. Only limited full-scale device data is available in order to inform designers of performance, due to only small numbers of o shore deployments. Smaller-scale laboratory testing can provide greater understanding of device performance and loading. Understanding device performance and loading are important as they will impact on projects finances by affecting energy yield and allowing extreme loading to be designed for to avoid unplanned maintenance. The loading of MCEC devices in constrained flow fields is currently not well understood at either full or laboratory-scale. The aim of this study is to investigate the influence of constrained flow fields on MCEC device loading and wake development. The results will inform: the limits of current analytical MCEC performance models, the calibration of empirical wake models, and the limits of existing computational fluid dynamic array models. The findings will therefore aid the development of design tools used in MCEC device modelling. This work presents the results from a series of small-scale laboratory static porous disk experiments in which the changes in loading and wake structure of a single device are characterised with variation in channel properties such as: area blockage ratio, Froude number and channel aspect ratio. Dual-array devices are also studied with the effects of device spacing and channel geometry upon wake formation and device loading characterised. Thrust coefficient is shown to be a function of Froude number, area blockage ratio and channel aspect ratio; with each non-dimensional parameter contributing significantly to differences in loading. Despite differences in thrust coefficient with changes in channel aspect ratio it is shown that one-dimensional linear momentum actuator disk theory models are capable of accounting for these differences. Wake velocity pro le, wake expansion, transition point from near to far wake and wake recovery are shown to be different in the vertical and horizontal planes in some channels geometries. Variation in channel geometry, i.e. the proximity of bounding surfaces, is shown to have an effect on these parameters indicating that it may be possible to calibrate semi-empirical wake models to predict wake development in either flows of constrained geometry or within array deployments. Device spacing in a dual-array is also shown to affect wake structure and device loading. The relationships between these two parameters are shown to be a function of device diameter/water depth ratio.
20
Doh, Yoonmee. "Voltage-clock scaling and scheduling for energy-constrained real-time systems." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000675.
21
Tsiontsiou, Evangelia. "Multi-constrained QoS Routing and Energy Optimization for Wireless Sensor Networks." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0340/document.
Анотація:
La thèse porte sur la conception de protocoles de routage pour les réseaux de capteurs. Les problèmes de recherche du routage de données dans un réseau multi-sauts sont d’une part l’optimisation de l’énergie et d’autre part le routage sous contraintes de la qualité de service (QoS) multicritères (e.g., énergie, fiabilité, délai, …). Cette thèse apporte deux contributions par rapport à l’état de l’art : une optimisation d'un protocole de routage probabiliste pour l'équilibre de l'usage d'énergie et un protocole de routage capable de prendre en compte simultanément des métriques de QoS multiples. En effet, pour équilibrer la consommation de l’énergie du routage lorsque des chemins multiples existent, les protocoles de routage probabiliste existants affectent une probabilité de choix à chaque chemin, soit de façon empirique, soit proportionnelle au niveau de l’énergie disponible du chemin. Nous ne savions pas quelles sont les probabilités optimales qui permettent d’avoir la durée de vie maximale du réseau. Cette thèse a permis d’établir ces probabilités optimales à l’aide de la modélisation sous forme d’un problème d’optimisation linéaire. Quant au problème du routage multicritères, bien que des métriques multiples soient définies par RPL (un standard d’IETF), les protocoles existants choisissent la route soit sur une métrique, soit sur une fonction de coût combinant plusieurs (qui introduit par conséquent un biais de pondération), mais jamais plusieurs simultanément. Dans cette thèse, nous avons d’abord évalué numériquement les performances de l’approche « operator calculus algebra » introduit par R. Schott et S. Staples qui définit un algorithme efficace permettant de trouver tous les chemins satisfaisant les contraintes multiples dans un graphe , puis dérivé une version distribuée sur laquelle nous avons conçu un protocole de routage multi-métriques. Ces deux contributions ont été implémentées dans l’environnement Contiki et émulées/simulées sous Cooja (un logiciel permettant de simuler des protocoles des réseaux de capteurs)In this thesis, we focus on routing protocols for Wireless Sensor Networks (WSNs). The main research problems in the domain of routing data packets in a multi-hop network are the optimisation of the energy and the routing under multi-criteria QoS constraints (e.g., energy, reliability, delay, …). To address these problems, this dissertation proposes two contributions. Firstly, an optimal probabilistic routing protocol which balances the usage of energy and secondly, a routing protocol which is able to simultaneously take into account multiple QoS metrics. In fact, for balancing the energy consumption between the multiple existing links, the existing probabilistic routing protocols assign a probability to each link, either in an empirical way or depending on proportional energy level of the path. We did not know what are the optimal probabilities which lead to the optimal network lifetime. Our first contribution proposes optimal probabilities by modeling and solving a linear programming problem. As for the multi-constrainted QoS routing problem, multiple metrics are defined by RPL (a standard of IETF) but the existing protocols chose paths either according to only one metric or using a single aggregated function with multiple metrics, but never all the metrics simultaneously. In this dissertation, we first evaluate the performance of the operator calculus algebra introduced by R. Schott and S. Staples which defines an efficient algorithm allowing to find all the paths which satisfy the multiple constraints in a graph, and secondly we proposed a distributed version of this algorithm based on which a routing protocol has been designed. Both contributions are implemented in Contiki environment and simulated/emulated under Cooja (a software designed for simulating protocols of WSNs)
22
Rossi, Maurizio. "Energy Neutral Design of Embedded Systems for Resource Constrained Monitoring Applications." Doctoral thesis, Università degli studi di Trento, 2016. https://hdl.handle.net/11572/368463.
Анотація:
Automatic monitoring of environments, resouces and human processes are crucial and foundamental tasks to improve people's quality of life and to safeguard the natural environment. Today, new technologies give us the possibility to shape a greener and safer future. The more specialized is the kind of monitoring we want to achieve, more tight are the constraints in terms of reliability, low energy and maintenance-free autonomy. The challenge in case of tight energy constraints is to find new techniques to save as much power as possible or to retrieve it from the very same environment where the system operates, towards the realization of energy neutral embedded monitoring systems. Energy efficiency and battery autonomy of such devices are still the major problem impacting reliability and penetration of such systems in risk-related activities of our daily life. Energy management must not be optimized to the detriment of the quality of monitoring and sensors can not be operated without supply. In this thesis, I present different embedded system designs to bridge this gap, both from the hardware and software sides, considering specific resource constrained scenarios as case studies that have been used to develop solutions with much broader validity. Results achieved demonstrate that energy neutrality in monitoring under resource constrained conditions can be obtained without compromising efficiency and reliability of the outcomes.
23
Rossi, Maurizio. "Energy Neutral Design of Embedded Systems for Resource Constrained Monitoring Applications." Doctoral thesis, University of Trento, 2016. http://eprints-phd.biblio.unitn.it/1717/1/thesis_final_mR.pdf.
Анотація:
Automatic monitoring of environments, resouces and human processes are crucial and foundamental tasks to improve people's quality of life and to safeguard the natural environment. Today, new technologies give us the possibility to shape a greener and safer future. The more specialized is the kind of monitoring we want to achieve, more tight are the constraints in terms of reliability, low energy and maintenance-free autonomy. The challenge in case of tight energy constraints is to find new techniques to save as much power as possible or to retrieve it from the very same environment where the system operates, towards the realization of energy neutral embedded monitoring systems. Energy efficiency and battery autonomy of such devices are still the major problem impacting reliability and penetration of such systems in risk-related activities of our daily life. Energy management must not be optimized to the detriment of the quality of monitoring and sensors can not be operated without supply. In this thesis, I present different embedded system designs to bridge this gap, both from the hardware and software sides, considering specific resource constrained scenarios as case studies that have been used to develop solutions with much broader validity. Results achieved demonstrate that energy neutrality in monitoring under resource constrained conditions can be obtained without compromising efficiency and reliability of the outcomes.
24
GATTO, EMANUELA. "Conformationally constrained peptides as new nanomaterials for electrons and energy transfer." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/606.
Анотація:
In this thesis the electron mediating properties of 310 helical peptides have been investigated, both in solution and on gold surfaces, by means of photochemical, electrochemical and photoelectrochemical methods.
The directional character of the electron transfer process along helical oligopeptides as a result of the electrostatic field associated to the helix macrodipole is demostrated. It is shown that this effect is smaller for a 310 helix than that in a alpha-helix, because of the carbonyl dipole distortion with respect to the helical axis. For very short peptides the helix macrodipole does not affect very much the redox potential of the probe and of the gold surfaces, but it affects the electron transfer rate toward the gold substrate.
The ability of short helical peptides to generate photocurrent is also demonstrated, together with the possibility of constructing a molecular photodiode able to switch the current direction.
It is also shown that the gold substrate on which the a peptide SAM is built up strongly influences the photocurrent efficiency, showing the maximum value for interdigitated gold microelectrodes, in which the substrate is Si3N4.
Furthemore, a new approach is utilized for the construction of a mixed SAM , making use of the helix-helix macrodipoles interaction. By these favourable interactions, a peptide has been intercalated into a covalently linked peptide SAM. Both peptides have been functionalized by a photoactive group, so that it could be possible to switch the direction of the generated current by selective excitation of the two peptides.
All these results confirm the very good electron mediating properties of helical peptides, and make them very promising materials for the development of molecular devices based on peptide molecular wires.
25
Eriksson, Simon. "System Analysis of Energy-Constrained Quality of Service and Power Management Techniques." Thesis, KTH, Maskinkonstruktion (Inst.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99457.
Анотація:
This master’s thesis is a part of the GEODES project, Global Energy Optimization for Distributed Embedded Systems, and deals with the issues regarding energy-constrained Quality of Service , QoS, in real time embedded systems. Due to the development in the areas of embedded systems, new demands have arisen. Especially for mobile devices, the increase of functionality has overrun the development of batteries. To deal with these kinds of problems a new aspect of QoS has become of interest. The new aspect is to bring power awareness into the system. Power awareness means to enable enhancements or guarantees for the lifetime of a device through intelligent software. For online decision making a software component, an energy-constrained QoS manager, is needed. The manager module may be distributed in a system or dispatched locally. The mission is to decrease power consumption by the cost of lesser performance of the system. This procedure is called to introduce system degradation into the system. A lot the research in the power management field targets single components. This thesis aims to investigate the possibilities in system level management. An analysis of existing energy-constrained QoS and power management frameworks and techniques has been made, both on system level and on component level. As a result of the analysis a specification for the interface and policies of an energy-constrained QoS power manager is presented. A fundamental choice in the specification and design was that the system in hand consist of power manageable components , PMCs, which can be seen as atomic black boxes. This modeling choice was shown to be complicated to apply in real life systems and a solution proposal for interdependencies of PMCs is discussed. A design and a prototype, the Power Manager E , PME, module, has been implemented that tries to fulfill the specifications created from the analysis. The design handles both hardware and software as PMCs and optimizes for system performance under an energy constraint, expressed through desired system runtime, set by the user of the system. The prototype is implemented on an i.MX31 platform from Freescale and runs as a module to operating system OSE 5.4 Delta provided by ENEA.Examensarbetet är en del av GEODES projektet, Global Energy Optimization for Distributed Embedded Systems. Arbetet hanterar frågor som rör energistyrd Quality of Service , QoS, i inbyggda realtidssystem. Genom den senaste utvecklingen inom området inbyggda system har nya krav introducerats. Speciellt för mobila enheter, där tillkomsten av ny funktionalitet har gått snabbare än utvecklingen av batterikapacitet. För att hantera detta så har en ny aspekt av QoS fått större intresse. Den nya aspekten är att utveckla system med en medveten energikonsumtion. Energimedvetenhet innebär mjukvara som möjliggör förbättringar eller garantier för körtiden av systemet, online eller offline. För beslut online krävs en mjukvarukomponent, en mjukvarumodul för energistyrd QoS. Uppdraget för mjukvarumodulen är att minska strömförbrukningen till kostnaden av lägre prestanda hos systemet. Detta förfarande kallas för att införa kontrollerad system degradering i systemet. Forskningen inom området koncentrerar sig mest på att minska energikonsumtionen för enskilda komponenter. I detta examensarbete så är siktet ställt på att hitta metoder som fungerar på systemnivå. En analys av befintliga ramverk och tekniker för mjukvarukontrollerad energikonsumtion samt energistyrd QoS har genomförts, både på systemnivå och på komponentnivå. Resultatet av analysen presenteras av en specifikation för en energistyrd QoS styrmodul anpassad för kontroll på systemnivå. Ett grundläggande antagande i specifikationen och implementeringen var att systemet i fråga består av komponenter med ställbar energiförbrukning. Dessa komponenter kan ses som fristående oberoende funktionaliteter. Modellantagande visade sig vara komplicerat att tillämpa på verkliga system och ett lösningsförslag vid beroenden mellan komponenter diskuteras. En design och en prototyp Power Manager E , PME, har skapats enligt den specifikation som tagits fram i rapporten. Den hanterar både hårdvara och mjukvara som ställbara komponenter och försöker optimera systemets prestanda under krav på energikonsumtion. Kravet ställs av användaren genom en önskad körtid av systemet. Protoypen är byggd på en i.MX31-plattform från Freescale och är en tilläggsmodul till OSE5.4 Delta från ENEA.
26
Daga, Anil Kumar Namuduri Kameswara. "Source channel separation in energy constrained multiterminal source-channel communications schemes subtitle /." Diss., A link to full text of this thesis in SOAR, 2006. http://soar.wichita.edu/dspace/handle/10057/621.
Анотація:
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical and Computer Engineering."December 2006." Title from PDF title page (viewed on Oct. 29, 2007). Thesis adviser: Kamesh Namuduri. Includes bibliographic references (leaves 28-30).
27
WANG, XUN. "ON CONSTRAINED CONTOUR ENERGY MINIMIZATION: A NEW APPROACH TO DEFORMABLE CONTOUR METHODS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1106795223.
28
Tembo, B. "Strategic investment decisions in Zambia's mining sector under a constrained energy system." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10048151/.
Анотація:
This thesis studies the challenge of balancing between economic growth and social development that many developing countries are facing. The study sought to understand the impacts that these goals have on each other and how these impacts could be minimised. It looked at how clean energy access is modelled in developing countries and also how growth in Zambia’s mining sector would be impacted by meeting the government’s clean energy access targets in the residential sector. On one hand, increasing access to clean energy would lead to increase in energy demand, which would, in turn, imply increased capital investment in the energy supply system. This augmented investment means increase in energy prices which in turn would limit the growth of the mining sector (the backbone of the economy). Limited growth implicitly means reduced funding for clean energy projects. Thus, in order to adequately capture these complex interactions, three bottom-up models were developed: energy demand, energy supply and mining models. The energy models sought to understand how energy demand would evolve by 2050 and how much capital investment would be required to meet this demand. The mining model focused on understanding how developments in the energy sector would impact strategic investment decisions in the mining sector. It was found that approaches used to study how households transition from one energy fuel to another in developing countries had significant conceptual errors. However, these errors could be minimised by using a bottom-up approach. Furthermore, it was found that while profit margins would reduce as a result of increase in energy prices, the impact of these prices on the firm’s production output was negligible - except if a firm is a marginal mine operation. The output was not impacted because mining firms make decisions based on thresholds and not marginal decrease in profits. Thus, even though reliable energy supply is critical in mining operations, the influence of energy price in investment decision making in Zambia’s mining sector is limited. The key decision variables in the sector were found to be copper price, grade and type of ore.
29
Tang, Kun. "Improving the Performance and Energy Efficiency for Power-constrained High Performance Computing." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/467325.
Анотація:
Computer and Information SciencePh.D.
The continuous growth in computing capability has expedited the scientific discovery and enabled scientific applications to simulate physical phenomena for increased problem sizes. However, as the computing capability escalates, power constraints are becoming a first-order concern for high performance computing (HPC) facilities. For example, the U.S. Department of Energy has set a power constraint of 20 MW to each exascale machine. How to achieve the target performance under power constraints remains to be an issue. Therefore, efficient operation of these facilities requires power constraints to be taken into account at all layers, which potentially impacts the performance and energy efficiency. In order to improve the performance and energy efficiency for computing and storage resources under power constraints, I proposed the following three techniques. First, I developed a power-aware checkpointing model through exploring the interplay among power capping, temperature, reliability, performance, and energy efficiency. Applying the model leads to maximized performance and energy efficiency, and minimized data movements over storage systems. Second, I characterized the performance and energy efficiency of HPC workflows on heterogeneous processors. In addition, I also characterized how scientific simulation and analysis react to power capping differently and how they vary based on error resilience. Based on the characterization of HPC workflows, I developed a reliability-aware platform configuration model to determine the optimal platform configuration which includes power allocation and distribution, power capping levels, and computing scales for power-constrained HPC workflows. Third, I developed a proactive burst buffer draining scheme to minimize the I/O provisioning requirement of permanent storage systems while preserving the system I/O performance. Facing power constraints, reducing the storage provisioning level directly decreases the power consumption of storage systems. Applying the proactive burst buffer draining scheme minimizes the storage provisioning level and power consumption without compromising the storage I/O performance.
Temple University--Theses
30
Lai, Yeh-Hung. "The constrained blister - a nearly constant strain energy release rate test for adhesives." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/44077.
Анотація:
This study developed and analyzed a modification of the blister test permitting nearly constant strain energy release rate testing of adhesive bonds. The work consisted of three parts; (1) development of the testing technique to evaluate strain energy release rate and to record the time dependent nature of the fracture process, (2) numerical analysis of the constrained blister test to determine the applicability of an approximate solution for several materials, and (3) development of an. analytical technique to evaluate the strain energy release rate for relatively stiff specimens.
Master of Science
31
Jiang, Bo. "Energy Efficient Target Tracking in Wireless Sensor Networks: Sleep Scheduling, Particle Filtering, and Constrained Flooding." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/29963.
Анотація:
Energy efficiency is a critical feature of wireless sensor networks (WSNs), because sensor nodes run on batteries that are generally difficult to recharge once deployed. For target tracking---one of the most important WSN application types---energy efficiency needs to be considered in various forms and shapes, such as idle listening, trajectory estimation, and data propagation. In this dissertation, we study three correlated problems on energy efficient target tracking in WSNs: sleep scheduling, particle filtering, and constrained flooding.
We develop a Target Prediction and Sleep Scheduling protocol (TPSS) to improve energy efficiency for idle listening. We start with designing a target prediction method based on both kinematics and probability. Based on target prediction and proactive wake-up, TPSS precisely selects the nodes to awaken and reduces their active time, so as to enhance energy efficiency with limited tracking performance loss. In addition, we expand Sleep Scheduling to Multiple Target Tracking (SSMTT), and further reduce the energy consumption by leveraging the redundant alarm messages of interfering targets. Our simulation-based experimental studies show that compared to existing protocols such as Circle scheme and MCTA, TPSS and SSMTT introduce an improvement of 25% ~ 45% on energy efficiency, at the expense of only 5% ~ 15% increase on the detection delay.
Particle Filtering is one of the most widely used Bayesian estimation methods, when target tracking is considered as a dynamic state estimation problem for trajectory estimation. However, the significant computational and communication complexity prohibits its application in WSNs. We design two particle filters (PFs)---Vector space based Particle Filter (VPF) and Completely Distributed Particle Filter (CDPF)---to improve energy efficiency of PFs by reducing the number of particles and the communication cost. Our experimental evaluations show that even though VPF incurs 34% more estimation error than RPF, and CDPF incurs a similar estimation error to SDPF, they significantly improve the energy efficiency by as much as 68% and 90% respectively.
For data propagation, we present a Constrained Flooding protocol (CFlood) to enhance energy efficiency by increasing the deadline satisfaction ratio per unit energy consumption of time-sensitive packets. CFlood improves real-time performance by flooding, but effectively constrains energy consumption by controlling the scale of flooding---i.e., flooding only when necessary. If unicasting meets the distributed sub-deadline at a hop, CFlood aborts further flooding even after flooding has occurred in the current hop. Our simulation-based experimental studies show that CFlood achieves higher deadline satisfaction ratio per unit energy consumption by as much as 197%, 346%, and 20% than existing multipath forwarding protocols, namely, Mint Routing, MCMP and DFP respectively, especially in sparsely deployed or unreliable sensor network environments.
To verify the performance and efficiency of the dissertation's solutions, we developed a prototype implementation based on TelosB motes and TinyOS version 2.1.1. In the field experiments, we compared TPSS, VPF, CDPF, and CFlood algorithms/protocols to their respective competing efforts. Our implementation measurements not only verified the rationality and feasibility of the proposed solutions for target tracking in WSNs, but also strengthened the observations on their efficiency from the simulation.Ph. D.
32
Bahrami, Shahab. "Algorithm design for optimal power flow, security-constrained unit commitment, and demand response in energy systems." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62754.
Анотація:
Energy management is of prime importance for power system operators to enhance the use of the existing and new facilities, while maintaining a high level of reliability. In this thesis, we develop analytical models and efficient algorithms for energy management programs in transmission and distribution networks. First, we study the optimal power flow (OPF) in ac-dc grids, which is a non-convex optimization problem. We use convex relaxation techniques and transform the problem into a semidefinite program (SDP). We derive the sufficient conditions for zero relaxation gap and design an algorithm to obtain the global optimal solution. Subsequently, we study the security-constrained unit commitment (SCUC) problem in ac-dc grids with generation and load uncertainty. We introduce the concept of conditional value-at risk to limit the net power supply shortage. The SCUC is a nonlinear mixed-integer optimization problem. We use ℓ₁-norm approximation and convex relaxation techniques to transform the problem into an SDP. We develop an algorithm to determine a near-optimal solution. Next, we target the role of end-users in energy management activities. We study demand response programs for residential users and data centers. For residential users, we capture their coupled decision making in a demand response program with real-time pricing as a partially observable stochastic game. To make the problem tractable, we approximate the optimal scheduling policy of the residential users by the Markov perfect equilibrium (MPE) of a fully observable stochastic game with incomplete information. We develop an online load scheduling learning algorithm to determine the users’ MPE policy. Last but not least, we focus on the demand response program for data centers in deregulated electricity markets, where each data center can choose a utility company from multiple available suppliers. We model the data centers’ coupled decisions of utility company choices and workload scheduling as a many-to-one matching game with externalities. We characterize the stable outcome of the game, where no data center has an incentive to unilaterally change its strategy. We develop a distributed algorithm that is guaranteed to converge to a stable outcome.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
33
Daly, Denis Clarke. "Digital ADCs and ultra-wideband RF circuits for energy constrained wireless applications by Denis Clarke Daly." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53269.
Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 173-183).
Ongoing advances in semiconductor technology have enabled a multitude of portable, low power devices like cellular phones and wireless sensors. Most recently, as transistor device geometries reach the nanometer scale, transistor characteristics have changed so dramatically that many traditional circuits and architectures are no longer optimal and/or feasible. As a solution, much research has focused on developing 'highly digital' circuits and architectures that are tolerant of the increased leakage, variation and degraded voltage headrooms associated with advanced CMOS processes. This thesis presents several highly digital, mixed-signal circuits and architectures designed for energy constrained wireless applications. First, as a case study, a highly digital, voltage scalable flash ADC is presented. The flash ADC, implemented in 0.18 [mu]m CMOS, leverages redundancy and calibration to achieve robust operation at supply voltages from 0.2 V to 0.9 V. Next, the thesis expands in scope to describe a pulsed, noncoherent ultra-wideband transceiver chipset, implemented in 90 nm CMOS and operating in the 3-to-5 GHz band. The all-digital transmitter employs capacitive combining and pulse shaping in the power amplifier to meet the FCC spectral mask without any off-chip filters. The noncoherent receiver system-on-chip achieves both energy efficiency and high performance by employing simple amplifier and ADC structures combined with extensive digital calibration. Finally, the transceiver chipset is integrated in a complete system for wireless insect flight control.
(cont.) Through the use of a flexible PCB and 3D die stacking, the total weight of the electronics is kept to 1 g, within the carrying capacity of an adult Manduca sexta moth. Preliminary wireless flight control of a moth in a wind tunnel is demonstrated.
Ph.D.
34
He, Yingjie. "Data hovering algorithm for improving data retention and data quality in energy-constrained mobile wireless sensor networks." Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1453.
Анотація:
A Wireless Sensor Network (WSN) is composed of numerous spatially distributed, low cost, low power and multifunctional sensor nodes which can be used to monitor the surrounding environment. In mobile networks, the sensed data collected by the sensor nodes may move out of the area where it has been gathered (area of origin) with its carrying node. A problem may arise in this situation: when requesting the historical information of a specific area, it is possible that none of the nodes currently located in such area can provide the required information. This thesis addresses the issue of retaining data it its area of origin in an energy-constrained, infrastructure-less mobile Wireless Sensor Network. The concept of this “Data Hovering” has been defined in which the location-based data hovers in its area of origin by transmission between network nodes. Based on this concept, several policies need to be defined as well as considering the constraints of WSN including limited energy and limited transmission bandwidth. The existing related work has then been investigated by examining how it proposed to define the Data Hovering policies, in order to explore the limitations. It has been found that the existing approaches are not well suited to mobile WSN, due to the unique characteristics of WSN. In this thesis, an autonomous Data Hovering algorithm consisting of defined policies has been designed to improve the data retention (data availability) and the quality of the retained data which ensures that the retained data represents different information. The defined Data Hovering algorithm has been implemented in a network simulator and a baseline with simple policies has also been selected in order to be compared with the defined policies. The evaluation in terms of data availability, data quality and energy consumption has then been carried out to analyze the behaviours of the defined algorithm. Finally, the potential future work has been suggested.
35
Amini, Mahraz. "Optimal dispatch of uncertain energy resources." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1046.
Анотація:
The future of the electric grid requires advanced control technologies to reliably integrate high level of renewable generation and residential and small commercial distributed energy resources (DERs). Flexible loads are known as a vital component of future power systems with the potential to boost the overall system efficiency. Recent work has expanded the role of flexible and controllable energy resources, such as energy storage and dispatchable demand, to regulate power imbalances and stabilize grid frequency. This leads to the DER aggregators to develop concepts such as the virtual energy storage system (VESS). VESSs aggregate the flexible loads and energy resources and dispatch them akin to a grid-scale battery to provide flexibility to the system operator. Since the level of flexibility from aggregated DERs is uncertain and time varying, the VESSs’ dispatch can be challenging. To optimally dispatch uncertain, energy-constrained reserves, model predictive control offers a viable tool to develop an appropriate trade-off between closed-loop performance and robustness of the dispatch. To improve the system operation, flexible VESSs can be formulated probabilistically and can be realized with chance-constrained model predictive control.
The large-scale deployment of flexible loads needs to carefully consider the existing regulation schemes in power systems, i.e., generator droop control. In this work first, we investigate the complex nature of system-wide frequency stability from time-delays in actuation of dispatchable loads. Then, we studied the robustness and performance trade-offs in receding horizon control with uncertain energy resources. The uncertainty studied herein is associated with estimating the capacity of and the estimated state of charge from an aggregation of DERs.
The concept of uncertain flexible resources in markets leads to maximizing capacity bids or control authority which leads to dynamic capacity saturation (DCS) of flexible resources. We show there exists a sensitive trade-off between robustness of the optimized dispatch and closed-loop system performance and sacrificing some robustness in the dispatch of the uncertain energy capacity can significantly improve system performance. We proposed and formulated a risk-based chance constrained MPC (RB-CC-MPC) to co-optimize the operational risk of prematurely saturating the virtual energy storage system against deviating generators from their scheduled set-point. On a fast minutely timescale, the RB-CC-MPC coordinates energy-constrained virtual resources to minimize unscheduled participation of ramp-rate limited generators for balancing variability from renewable generation, while taking into account grid conditions. We show under the proposed method it is possible to improve the performance of the controller over conventional distributionally robust methods by more than 20%.
Moreover, a hardware-in-the-loop (HIL) simulation of a cyber-physical system consisting of packetized energy management (PEM) enabled DERs, flexible VESSs and transmission grid is developed in this work. A predictive, energy-constrained dispatch of aggregated PEM-enabled DERs is formulated, implemented, and validated on the HIL cyber-physical platform. The experimental results demonstrate that the existing control schemes, such as AGC, dispatch VESSs without regard to their energy state, which leads to unexpected capacity saturation. By accounting for the energy states of VESSs, model-predictive control (MPC) can optimally dispatch conventional generators and VESSs to overcome disturbances while avoiding undesired capacity saturation. The results show the improvement in dynamics by using MPC over conventional AGC and droop for a system with energy-constrained resources.
36
Zhang, Wang. "Optimisation and Integration of Variable Renewable Energy Sources in Electricity Networks." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16858.
Анотація:
The growing penetration of renewable energy sources (RESs) into the electricity power grid is profitable from a sustainable point of view and provides economic benefit for long-term operation. Nevertheless, balancing production and consumption is and will always be a crucial requirement for power system operation. However, the trend towards increasing RESs penetration has raised concerns about the stability, reliability and security of future electricity grids. The clearest observation in this regard is the intermittent nature of RESs. Moreover, the location of renewable generation tends to be heavily defined by meteorological and geographical conditions, which makes the generation sites distant from load centres. These facts make the analysis of electricity grid operation under both dynamic and the steady state more difficult, posing challenges in effectively integrating variable RESs into electricity networks. The thesis reports on studies that were conducted to design efficient tools and algorithms for system operators, especially transmission system operators for reliable short-term system operation that accounts for intermittency and security requirements. Initially, the impact of renewable generation on the steady state is studied in the operation stage. Then, based on the first study, more sophisticated modeling on the electricity network are investigated in the third and fourth chapters. Extending the previous studies, the fourth chapter explores the potential of using multiple microgrids to support the main grid’s security control. Finally, the questions regarding the computational efficiency and convergence analysis are addressed in chapter 5 and a DSM model in a real-time pricing environment is introduced. This model presents an alternative way of using flexibility on the demand side to compensate for the uncertainties on the generation side.
37
Wang, Qinghua. "Traffic analysis, modeling and their applications in energy-constrained wireless sensor networks on network optimization and anomaly detection /." Doctoral thesis, Sundsvall : Tryckeriet Mittuniversitetet, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-10690.
38
Crossland, Andrew Frederick. "Application of stochastic and evolutionary methods to plan for the installation of energy storage in voltage constrained LV networks." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10819/.
Анотація:
Energy storage is widely considered to be an important component of a decarbonised power system if large amounts of renewable generation are to provide reliable electricity. However, storage is a highly capital intensive asset and clear business cases are needed before storage can be widely deployed. A proposed business case is using storage to prevent overvoltage in low voltage (LV) distribution networks to enable residential photovoltaic systems. Despite storage being widely considered for use in LV networks, there is little work comparing where storage might be installed in LV networks from the perspective of the owners of distribution networks (DNOs). This work addresses this in two ways. Firstly, a tool is developed to examine whether DNOs should support a free market for energy storage in which customers with PV purchase storage (e.g. battery systems) to improve their self-consumption. This reflects a recent policy in Germany. Secondly, a new (published) method is developed which considers how DNOs should purchase and locate storage to prevent overvoltage. Both tools use a snapshot approach by modelling the highest and lowest LV voltages. On their own, these tools enable a DNO to determine the cost of energy storage for a particular LV network with a particular set of loads and with PV installed by a given set of customers. However, in order to predict and understand the future viability of energy storage it is valuable to apply the tools to a large number of LV networks under realistic future scenarios for growth of photovoltaics in the UK power system. Therefore, the work extracts over 9,000 LV network models containing over 40,000 LV feeders from a GIS map of cables provided by one of the UK’s electricity distribution networks- Electricity North West. Applying the proposed tools to these 9,000 network models, the work is able to provide projections for how much LV energy storage would be installed under different scenarios. The cost of doing so is compared to the existing method of preventing reinforcement- LV network reconductoring. This is a novel way of assessing the viability of LV energy storage against traditional approaches and allows the work to draw the following conclusions about the market for energy storage in LV distribution networks in the UK: - Overvoltage as a result of PV could begin to occur in the next few years unless UK regulations for voltage levels are relaxed. There could be a large cost (hundreds of millions of pounds) to prevent this if the traditional approach of reconductoring is used. - If overvoltage begins to occur, a free market for energy storage (randomly purchased by electricity consumers) cannot offer large benefits to DNOs in reducing the reinforcement cost unless this is properly controlled, located and/or widely installed by customers. - Optimally located storage by the DNO can reduce overall reinforcement costs to mitigate overvoltage. This would enable more energy storage to balance renewable generation and present large savings to the power system. The exact topology of storage and the storage rating in each LV network could be determined using the tool proposed in this work.
39
Wägemann, Peter [Verfasser], Peter [Akademischer Betreuer] Puschner, and Wolfgang [Gutachter] Schröder-Preikschat. "Energy-Constrained Real-Time Systems and Their Worst-Case Analyses / Peter Wägemann ; Gutachter: Wolfgang Schröder-Preikschat ; Betreuer: Peter Puschner." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1219736864/34.
40
Devlin, Joseph. "A gas energy flow constrained unit commitment analysis of the British and Irish power systems considering high wind power penetrations." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706454.
Анотація:
As members of the European Union (EU), the United Kingdom (UK) and Ireland are legally bound to integrate large penetrations of renewable energy into the power system in pursuit of EU 2020 targets. Wind power has emerged as the main renewable energy technology of choice to meet these targets. As the penetration of wind power continues to increase beyond 2020, a wider lens on the integration problem is required, It has been previously shown that gas generation due to its flexibility provision and traditionally high place in the merit order is the sacrificial generator. The ensuing dispatch schedule reduces energy output and incorporates a high degree of variability. This increasingly variable output profile is ultimately transferred onto gas infrastructure and is a relatively overlooked area of research This work is the first to utilise a fully realistic gas energy flow, security and reserve constrained unit commitment and economic dispatch model to investigate the interactions between power and gas vectors In the Interconnected energy systems of the UK and Ireland. Utilisation of this novel modelling methodology produced four key deliverables, Firstly, the real world impact of high wind power penetrations on gas generators in the SEM during 2011 were analysed in detail The second deliverable, novel utilisation of grid scale electrical storage coupled to a constrained on gas generating unit in the SEM during 2020, was shown to have significant impacts on peak' time system operation. Thirdly, the multi vector analysis conducted enabled the value of gas infrastructure to power system operation in the SEM to be determined, Finally, the research highlights the ability of extreme weather driven gas demand to impact unit commitment decisions in both the SEM and BETTA. Additionally, the presence of gas storage in Ireland is shown to significantly improve power and gas security of supply.
41
Hall, Braydon Day. "The Dynamic Analysis of a Composite Overwrapped Gun Barrel with Constrained Viscoelastic Damping Layers Using the Modal Strain Energy Method." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1972.
Анотація:
The effects of a composite overwrapped gun barrel with viscoelastic damping layers are investigated. Interlaminar stresses and constrained layer damping effects are described. The Modal Strain Energy method is developed for measuring the extent to which the barrel is damped. The equations of motion used in the finite element analysis are derived. The transient solution process is outlined. Decisions for selected parameters are discussed. The results of the finite element analyses are presented using the program written in FORTRAN. The static solution is solved with a constant internal pressure resulting in a calculated loss factor from the Modal Strain Energy Method. The transient solution is solved using the Newmark-Beta method and a variable internal pressure. The analyses conclude that strategically placed viscoelastic layers dissipate strain energy more effectively than a thick single viscoelastic layer. The optimal angle for maximizing the coefficient of mutual influence in a composite cylinder is not necessarily the optimal angle when viscoelastic layers are introduced between layers.
42
Liu, Yue. "A Policy and Economic Comparative Study of Carbon Capture & Storage (CCS) and Renewable Energy Technologies in Australia within a Carbon-Constrained World." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1854.
Анотація:
This study assessed potential contributions of the renewable energy technologies (RETs) and CCS technologies in reducing carbon emissions and meeting energy demand in the Australian National and Wholesale Electricity Markets consistent with Australian Governmental policies, at the least cost to society by 2049-50. It suggested that government’s current post-2020 carbon reduction target will result in the lowest capacity expansion cost by employing both the RETs and CCS technologies compared to implementing more ambitious reduction targets.
43
Zengin, Asli. "Energy-efficient Routing To Maximize Network Lifetime In Wireless Sensor Networks." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608626/index.pdf.
Анотація:
With various new alternatives of low-cost sensor devices, there is a strong demand for large scale wireless sensor networks (WSN). Energy efficiency in routing is crucial for achieving the desired levels of longevity in these networks. Existing routing algorithms that do not combine information on transmission energies on links, residual energies at nodes, and the identity of data itself, cannot reach network capacity. A proof-of-concept routing algorithm that combines data aggregation with the minimum-weight path routing is studied in this thesis work. This new algorithm can achieve much larger network lifetime when there is redundancy in messages to be carried by the network, a practical reality in sensor network applications.
44
Asuncion, Janice Sy. "The Geographic Adaptive Potential of Freight Transportation and Production System in the Context of Fuel and Emission Constraints." Thesis, University of Canterbury. Department of Mechanical Engineering, 2014. http://hdl.handle.net/10092/9230.
Анотація:
Freight transportation is an integral element of various supply chains and has a complex and dynamical interrelationship with human economic activities. Modern logistical strategies paved way to the current supply chain organisation and logistics network design resulting in a more global economy and huge economies of scale. Recent trends of volatility of oil price have major implications in the movement of commodities across the supply chains. Likewise, climate change issues have presented urgent challenges in reducing carbon emissions for the transport and logistics sector. Pressure on the sector comes from both governments and consumers alike, demanding future sustainability as well as corporate environmental and social responsibility.
The original contribution of this research is to investigate the system-wide dynamics of freight transportation and production in the context of supply chains. A theoretical framework called the ‘Geographic Adaptive Potential’ or GAP is built to understand how constraints in energy and emissions affect the production and distribution of commodities. The changes in the supply chain were investigated in four different components, namely a) the potential to shift to less energy and emissions intensive modes for long-haul freight, b) logistical strategies in the last leg of the chain or urban freight and c) local production and distribution, and d) the accessibility of potential customers to the markets.
The design of the GAP components is in correspondence with the links of the supply chain. The analyses yielded an evaluation of the adaptive capacity of the freight transport and production system. For long-haul freight, a GIS-based model was created called the ‘New Zealand Intermodal Freight Network’ or NZIFN. It is an optimisation tool integrating the road, rail and shipping network of New Zealand and calculates that minimum time, operating costs, energy and emissions routes between 2 given locations. The case studies of Auckland to Wellington and Auckland to Christchurch distributions of non-perishable products established that even a marginal increase of rail and coastal shipping share produced around 10% reduction in both freight energy and greenhouse gas emissions.
In the study of the last leg of the supply chain, the truck trip generation rates of different food stores were investigated. The strongest factors influencing the trip rates to a store are its size and product variation, the latter being a new parameter introduced in the dissertation. It is defined as the total number of brands for 6 chosen commodities commonly found in the stores. The trip rates together with the truck type and distance travelled were used to compute the freight energy usage of the stores. Results revealed that supermarkets consume the most energy for their delivery operations but relative to its physical size, they are more energy efficient than smaller stores. This is due to the utilisation of advanced logistical strategies such as freight consolidation and the effective use of distribution centres.
The localised production chapter was explored in the context of Farmers’ markets and their difference with the conventional supermarket distribution system. Using a freight transport energy audit, the energy intensities of both systems were compared. The findings showed that Farmers’ markets were more energy-intensive than supermarkets owing to the low volumes of goods delivered to the market and the lack of freight consolidation effort in the system.
The study on the active mode access of potential customers to both Farmers’ markets and supermarkets captured the interplay between freight and personal transport and is the final component of GAP. The results of the ArcGIS based model called ‘Active Mode Access’ or AMA demonstrated that both Farmers’ markets and supermarkets have the same level of accessibility for walking or biking customers. However, the calculations also showed that almost 87% of New Zealanders have no AMA to stores and are at risk for fuel price increase.
Finally, the key result of this dissertation is the assessment that there is actually limited adaptive capacity of the freight transport and production system. This is due to network infrastructure and geographical constraints as well as commodity type and mode compatibility and other operational concerns. Due to these limitations, the GAP model assessed that reduction in energy and allowable emissions will ultimately reduce the amount of commodities moved in the system.
45
Ibrahim, Sarmad Khaleel. "DISTRIBUTION SYSTEM OPTIMIZATION WITH INTEGRATED DISTRIBUTED GENERATION." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/116.
Анотація:
In this dissertation, several volt-var optimization methods have been proposed to improve the expected performance of the distribution system using distributed renewable energy sources and conventional volt-var control equipment: photovoltaic inverter reactive power control for chance-constrained distribution system performance optimisation, integrated distribution system optimization using a chance-constrained formulation, integrated control of distribution system equipment and distributed generation inverters, and coordination of PV inverters and voltage regulators considering generation correlation and voltage quality constraints for loss minimization. Distributed generation sources (DGs) have important benefits, including the use of renewable resources, increased customer participation, and decreased losses. However, as the penetration level of DGs increases, the technical challenges of integrating these resources into the power system increase as well. One such challenge is the rapid variation of voltages along distribution feeders in response to DG output fluctuations, and the traditional volt-var control equipment and inverter-based DG can be used to address this challenge.
These methods aim to achieve an optimal expected performance with respect to the figure of merit of interest to the distribution system operator while maintaining appropriate system voltage magnitudes and considering the uncertainty of DG power injections. The first method is used to optimize only the reactive power output of DGs to improve system performance (e.g., operating profit) and compensate for variations in active power injection while maintaining appropriate system voltage magnitudes and considering the uncertainty of DG power injections over the interval of interest. The second method proposes an integrated volt-var control based on a control action ahead of time to find the optimal voltage regulation tap settings and inverter reactive control parameters to improve the expected system performance (e.g., operating profit) while keeping the voltages across the system within specified ranges and considering the uncertainty of DG power injections over the interval of interest. In the third method, an integrated control strategy is formulated for the coordinated control of both distribution system equipment and inverter-based DG. This control strategy combines the use of inverter reactive power capability with the operation of voltage regulators to improve the expected value of the desired figure of merit (e.g., system losses) while maintaining appropriate system voltage magnitudes. The fourth method proposes a coordinated control strategy of voltage and reactive power control equipment to improve the expected system performance (e.g., system losses and voltage profiles) while considering the spatial correlation among the DGs and keeping voltage magnitudes within permissible limits, by formulating chance constraints on the voltage magnitude and considering the uncertainty of PV power injections over the interval of interest.
The proposed methods require infrequent communication with the distribution system operator and base their decisions on short-term forecasts (i.e., the first and second methods) and long-term forecasts (i.e., the third and fourth methods). The proposed methods achieve the best set of control actions for all voltage and reactive power control equipment to improve the expected value of the figure of merit proposed in this dissertation without violating any of the operating constraints. The proposed methods are validated using the IEEE 123-node radial distribution test feeder.
46
Lüders, Michael [Verfasser], Doris [Akademischer Betreuer] Schmitt-Landsiedel, Walter [Gutachter] Stechele, and Doris [Gutachter] Schmitt-Landsiedel. "A Fully-Integrated, Digitally-Enhanced Low-Dropout Voltage Regulator for Energy-Constrained Microcontroller Systems / Michael Lüders ; Gutachter: Walter Stechele, Doris Schmitt-Landsiedel ; Betreuer: Doris Schmitt-Landsiedel." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1182536123/34.
47
Dutia, Dharini. "Multi-Robot Task Allocation and Scheduling with Spatio-Temporal and Energy Constraints." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1298.
Анотація:
Autonomy in multi-robot systems is bounded by coordination among its agents. Coordination implies simultaneous task decomposition, task allocation, team formation, task scheduling and routing; collectively termed as task planning. In many real-world applications of multi-robot systems such as commercial cleaning, delivery systems, warehousing and inventory management: spatial & temporal constraints, variable execution time, and energy limitations need to be integrated into the planning module. Spatial constraints comprise of the location of the tasks, their reachability, and the structure of the environment; temporal constraints express task completion deadlines. There has been significant research in multi-robot task allocation involving spatio-temporal constraints. However, limited attention has been paid to combine them with team formation and non- instantaneous task execution time. We achieve team formation by including quota constraints which ensure to schedule the number of robots required to perform the task. We introduce and integrate task activation (time) windows with the team effort of multiple robots in performing tasks for a given duration. Additionally, while visiting tasks in space, energy budget affects the robots operation time. We map energy depletion as a function of time to ensure long-term operation by periodically visiting recharging stations. Research on task planning approaches which combines all these conditions is still lacking. In this thesis, we propose two variants of Team Orienteering Problem with task activation windows and limited energy budget to formulate the simultaneous task allocation and scheduling as an optimization problem. A complete mixed integer linear programming (MILP) formulation for both variants is presented in this work, implemented using Gurobi Optimizer and analyzed for scalability. This work compares the different objectives of the formulation like maximizing the number of tasks visited, minimizing the total distance travelled, and/or maximizing the reward, to suit various applications. Finally, analysis of optimal solutions discover trends in task selection based on the travel cost, task completion rewards, robot's energy level, and the time left to task inactivation.
48
Sampathnarayanan, Balaji. "Analysis and Design of Stable and Optimal Energy Management Strategies for Hybrid Electric Vehicles." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357079732.
49
Roseveare, Nicholas. "Optimization and resource management in wireless sensor networks." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15730.
Анотація:
Doctor of PhilosophyDepartment of Electrical and Computer Engineering
Balasubramaniam Natarajan
In recent years, there has been a rapid expansion in the development and use of low-power, low-cost wireless modules with sensing, computing, and communication functionality. A wireless sensor network (WSN) is a group of these devices networked together wirelessly. Wireless sensor networks have found widespread application in infrastructure, environmental, and human health monitoring, surveillance, and disaster management. While there are many interesting problems within the WSN framework, we address the challenge of energy availability in a WSN tasked with a cooperative objective. We develop approximation algorithms and execute an analysis of concave utility maximization in resource constrained systems. Our analysis motivates a unique algorithm which we apply to resource management in WSNs. We also investigate energy harvesting as a way of improving system lifetime. We then analyze the effect of using these limited and stochastically available communication resources on the convergence of decentralized optimization techniques. The main contributions of this research are: (1) new optimization formulations which explicitly consider the energy states of a WSN executing a cooperative task; (2) several analytical insights regarding the distributed optimization of resource constrained systems; (3) a varied set of algorithmic solutions, some novel to this work and others based on extensions of existing techniques; and (4) an analysis of the effect of using stochastic resources (e.g., energy harvesting) on the performance of decentralized optimization methods. Throughout this work, we apply our developments to distribution estimation and rate maximization. The simulation results obtained help to provide verification of algorithm performance. This research provides valuable intuition concerning the trade-offs between energy-conservation and system performance in WSNs.
50
Sahin, Cem. "Optimization Of Electricity Markets In The Price Based And Security Constrained Unit Commitment Problems Frameworks." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612242/index.pdf.
Анотація:
Operation of the electricity markets is subject to a number of strict and specific constraints such as continuous load-generation balance, security of supply, and generation technology related limitations. Contributions have been made to two important problems of the Electricity Markets, in the context of this study.
In this study, Price Based Unit Commitment problem in the literature, which is a tool for the GENCO for operations planning, is extended considering the interdependencies between the Natural Gas (NG) and Electricity infrastructures and the uncertainty of Wind Power generation. The effect of the NG infrastructure physical limitations is considered via linearized NG transmission system equations, and the Wind energy sources and conventional generation resource uncertainties are simulated by Monte-Carlo simulations. The contribution of the forward energy Bilateral Contracts (BC), as a financial risk hedging tool is also included by modeling these in the proposed PBUC framework. In the case studies , it is observed that a GENCO could prevent its financial losses due to NG interruptions, by depositing only a portion of the midterm interrupted NG in the storage facilities.
The Security Constrained Unit Commitment (SCUC) Problem is widely accepted tool in the industry which models the market clearing process. This study integrates two novelties to the SCUC problem&bull
A discrete demand response model to consider active participation of the consumers, &bull
A hybrid deterministic/stochastic contingency model to represent the N-1 contingencies together with the uncertainties related with the wind power generation and system load. It is observed that the curtailment of available wind power capacity would enable the TSO to take corrective actions against occurrence of the contingencies and realization of the uncertainties in the most possible economical manner.