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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

O problema do caixeiro alugador com coleta de bonus: um estudo algoritmico / Prize Collecting Traveling Car Renter Problem: an Algotithm Study

Menezes, Matheus da Silva 21 March 2014 (has links)
Made available in DSpace on 2015-03-03T15:48:41Z (GMT). No. of bitstreams: 1 MatheusSM_TESE.pdf: 3657538 bytes, checksum: 05bf71663b044728a1e70b6db57b834e (MD5) Previous issue date: 2014-03-21 / This paper introduces a new variant of the Traveling Car Renter Problem, named Prizecollecting Traveling Car Renter Problem. In this problem, a set of vertices, each associated with a bonus, and a set of vehicles are given. The objective is to determine a cycle that visits some vertices collecting, at least, a pre-defined bonus, and minimizing the cost of the tour that can be traveled with different vehicles. A mathematical formulation is presented and implemented in a solver to produce results for sixty-two instances. The proposed problem is also subject of an experimental study based on the algorithmic application of four metaheuristics representing the best adaptations of the state of the art of the heuristic programming.We also provide new local search operators which exploit the neighborhoods of the problem, construction procedures and adjustments, created specifically for the addressed problem. Comparative computational experiments and performance tests are performed on a sample of 80 instances, aiming to offer a competitive algorithm to the problem. We conclude that memetic algorithms, computational transgenetic and a hybrid evolutive algorithm are competitive in tests performed / Este trabalho apresenta uma nova variante do problema do Caixeiro Alugador ainda n?o descrita na literatura, denominada de Caixeiro Alugador com Coleta de Pr?mios. Neste problema s?o disponibilizados um conjunto de v?rtices, cada um com um b?nus associado e um conjunto de ve?culos. O objetivo do problema ? determinar um ciclo que visite alguns v?rtices coletando, pelo menos, um b?nus pr?-de nido e minimizando os custos de viagem atrav?s da rota, que pode ser feita com ve?culos de diferentes tipos. ? apresentada uma formula??o matem?tica e implementada em um solver produzindo resultados em sessenta e duas inst?ncias. O problema proposto tamb?m ? objeto de um estudo algor?tmico experimental baseado na aplica??o de quatro metaheur?sticas de solu??o, representando adapta??es do melhor do estado da arte em programa??o heur?stica. Nesse trabalho tamb?m apresentamos a constitui??o de novos operadores que exploram as vizinhan?as do problema, procedimentos construtivos e adapta??es, criados especifi camente para o problema abordado. Experimentos computacionais comparativos e testes de desempenho s?o realizados sobre uma amostra de 80 inst?ncias, visando oferecer um algoritmo de solu??o competitivo para o problema. Conclui-se que algoritmos com abordagem mem?tica, transgen ?tica e evolucion?ria h?brida obtiveram resultados competitivos nos testes efetuados. Palavras-chave: Caixeiro Alugador com Coleta de Pr?mios. Metaheur?sticas. GRASP/VNS. Algoritmo Mem?tico. Transgen?tica Computacional. Computa??o Evolucion?ria
152

Hybrid Evolutionary Metaheuristics for Multiobjective Decision Support / Métaheuristiques hybrides évolutionnaires pour l'aide à la décision multi-objectifs

Kafafy, Ahmed 24 October 2013 (has links)
La prise de décision est une partie intégrante de notre vie quotidienne où le décideur est confronté à des problèmes composés de plusieurs objectifs habituellement contradictoires. Dans ce travail, nous traitons des problèmes d'optimisation multiobjectif dans des espaces de recherche continus ou discrets. Nous avons développé plusieurs nouveaux algorithmes basés sur les métaheuristiques hybrides évolutionnaires, en particulier sur l'algorithme MOEA/D. Nous avons proposé l'algorithme HEMH qui utilise l'algorithme DM-GRASP pour construire une population initiale de solutions de bonne qualité dispersées le long de l'ensemble des solutions Pareto optimales. Les résultats expérimentaux montrent la supériorité de toutes les variantes hybrides proposées sur les algorithmes originaux MOEA/D et SPEA2. Malgré ces bons résultats, notre approche possède quelques limitations, levées dans une version améliorée de HEMH : HEMH2 et deux autres variantes HEMHde et HEMHpr. Le Adaptive Binary DE inclus dans les HEMH2 et HEMHde a de meilleures capacités d'exploration qui pallient aux capacités de recherche locale contenues dans la HEMH, HEMH2 et HEMHde. Motivés par ces résultats, nous avons proposé un nouvel algorithme baptisé HESSA pour explorer un espace continu de recherche où le processus de recherche est réalisé par différentes stratégies de recherche. Les résultats expérimentaux montrent la supériorité de HESSA à la fois sur MOEA/D et dMOPSO. Tous les algorithmes proposés ont été vérifiés, testé et comparés à certaines méthodes MOEAs. Les résultats expérimentaux montrent que toutes les propositions sont très compétitives et peuvent être considérés comme une alternative fiable / Many real-world decision making problems consist of several conflicting objectives, the solutions of which is called the Pareto-optimal set. Hybrid metaheuristics proved their efficiency in solving these problems. They tend to enhance search capabilities by incorporating different metaheuristics. Thus, we are concerned with developing new hybrid schemes by incorporating different strategies with exploiting the pros and avoiding the drawback of the original ones. First, HEMH is proposed in which the search process includes two phases DMGRASP obtains an initial set of efficient solutions in the 1st phase. Then, greedy randomized path-relinking with local search or reproduction operators explore the non-visited regions. The efficient solutions explored over the search are collected. Second, a comparative study is developed to study the hybridization of different metaheuristics with MOEA/D. The 1st proposal combines adaptive discrete differential Evolution with MOEA/D. The 2nd combines greedy path-relinking with MOEA/D. The 3rd and the 4th proposals combine both of them in MOEA/D. Third, an improved version of HEMH is presented. HEMH2 uses inverse greedy to build its initial population. Then, differential evolution and path-relink improves these solutions by investigating the non-visited regions in the search space. Also, Pareto adaptive epsilon concept controls the archiving process. Motivated by the obtained results, HESSA is proposed to solve continuous problems. It adopts a pool of search strategies, each of which has a specified success ratio. A new offspring is generated using a randomly selected one. Then, the success ratios are adapted according to the success of the generated offspring. The efficient solutions are collected to act as global guides. The proposed algorithms are verified against the state of the art MOEAs using a set of instances from literature. Results indicate that all proposals are competitive and represent viable alternatives
153

Meta-heurísticas Iterated Local Search, GRASP e Artificial Bee Colony aplicadas ao Job Shop Flexível para minimização do atraso total. / Meta-heuristics Iterated Local Search, GRASP and Artificial Bee Colony applied to Flexible Job Shop minimizing total tardiness.

Everton Luiz de Melo 07 February 2014 (has links)
O ambiente de produção abordado neste trabalho é o Job Shop Flexível (JSF), uma generalização do Job Shop (JS). O problema de programação de tarefas, ou jobs, no ambiente JS é classificado por Garey; Johnson e Sethi (1976) como NP-Difícil e o JSF é, no mínimo, tão difícil quanto o JS. O JSF é composto por um conjunto de jobs, cada qual constituído por operações. Cada operação deve ser processada individualmente, sem interrupção, em uma única máquina de um subconjunto de máquinas habilitadas. O principal critério de desempenho considerado é a minimização dos atrasos dos jobs. São apresentados modelos de Programação Linear Inteira Mista (PLIM) para minimizar o atraso total e o instante de término da última operação, o makespan. São propostas novas regras de prioridade dos jobs, além de adaptações de regras da literatura. Tais regras são utilizadas por heurísticas construtivas e são aliadas a estratégias cujo objetivo é explorar características específicas do JSF. Visando aprimorar as soluções inicialmente obtidas, são propostas buscas locais e outros mecanismos de melhoria utilizados no desenvolvimento de três meta-heurísticas de diferentes categorias. Essas meta-heurísticas são: Iterated Local Search (ILS), classificada como meta-heurística de trajetória; Greedy Randomized Adaptive Search (GRASP), meta-heurística construtiva; e Artificial Bee Colony (ABC), meta-heurística populacional recentemente proposta. Esses métodos foram selecionados por alcançarem bons resultados para diversos problemas de otimização da literatura. São realizados experimentos computacionais com 600 instâncias do JSF, permitindo comparações entre os métodos de resolução. Os resultados mostram que explorar as características do problema permite que uma das regras de prioridade propostas supere a melhor regra da literatura em 81% das instâncias. As meta-heurísticas ILS, GRASP e ABC chegam a conseguir mais de 31% de melhoria sobre as soluções iniciais e a obter atrasos, em média, somente 2,24% superiores aos das soluções ótimas. Também são propostas modificações nas meta-heurísticas que permitem obter melhorias ainda mais expressivas sem aumento do tempo de execução. Adicionalmente é estudada uma versão do JSF com operações de Montagem e Desmontagem (JSFMD) e os experimentos realizados com um conjunto de 150 instâncias também indicam o bom desempenho dos métodos desenvolvidos. / The production environment addressed herein is the Flexible Job Shop (FJS), a generalization of the Job Shop (JS). In the JS environment, the jobs scheduling problem is classified by Garey; Johnson and Sethi (1976) as NP-Hard and the FJS is at least as difficult as the JS. FJS is composed of a set of jobs, each consisting of operations. Each operation must be processed individually, without interruption, in a single machine of a subset of enabled machines. The main performance criterion is minimizing the jobs tardiness. Mixed Integer Linear Programming (MILP) models are presented. These models minimize the total tardiness and the completion time of the last operation, makespan. New priority rules of jobs are proposed, as well as adaptations of rules from the literature. These rules are used by constructive heuristics and are combined with strategies aimed at exploiting specific characteristics of FSJ. In order to improve the solutions initially obtained, local searches and other improvement mechanisms are proposed and used in the development of metaheuristics of three different categories. These metaheuristics are: Iterated Local Search (ILS), classified as trajectory metaheuristic; Greedy Randomized Adaptive Search (GRASP), constructive metaheuristic, and Artificial Bee Colony (ABC), recently proposed population metaheuristic. These methods were selected owing to their good results for various optimization problems in the literature. Computational experiments using 600 FJS instances are carried out to allow comparisons between the resolution methods. The results show that exploiting the characteristics of the problem allows one of the proposed priority rules to exceed the best literature rule in about 81% of instances. Metaheuristics ILS, GRASP and ABC achieve more than 31% improvement over the initial solutions and obtain an average tardiness only 2.24% higher than the optimal solutions. Modifications in metaheuristics are proposed to obtain even more significant improvements without increased execution time. Additionally, a version called Disassembly and Assembly FSJ (DAFJS) is studied and the experiments performed with a set of 150 instances also indicate good performance of the methods developed.
154

Predictive gaze in action selection within virtual reality

Bampouni, Elpida January 2020 (has links)
The human gaze is pivotal in motion planning and control. Gaze is typically directed at visual target sites prior to physical interactions with them. This proactive gaze (PEG) behavior has been observed in a multitude of physical situations. However, PEG has not been examined in virtual reality (VR). Identification of PEG in VR could be helpful for digital human modeling applications and human-robot interactions. In this study we asked 10 participants to perform a pick-and-place (PAP) task in VR while we were tracking gaze behavior. Our results indicate that PEG also occurs in VR. Furthermore, the action to reach directly towards the PAP object or walk to it before reaching, results in different gaze strategies. Relocating before a reach is associated with gaze to additional sites, such as the floor and the table upon which the object was placed. / Den mänskliga blicken är avgörande för planering och kontroll av rörelse. Blicken riktas vanligtvis mot visuella mål före interaktion med dessa. Denna proaktiva blick (eng. ’proactive gaze’; PEG) har observerats i många olika slags fysiska situationer. Dock har inte PEG undersökts i virtual reality (VR). Identifiering av PEG i VR skulle kunna vara användbart för applikationer med digital mänsklig modellering och människo-robotinteraktioner. I denna studie instruerade vi 10 försöksdeltagare att utföra en s.k. pick-and-place-uppgift (PAP) i en VR-miljö medan vi registrerade deltagarnas blick. Våra resultat indikerar att PEG också förekommer i VR. Vidare leder handlingen att direkt sträcka sig efter objektet till ett annorlunda blickbeteende jämfört med att först förflytta sig innan man sträcker sig efter PAP-objektet. Vid förflyttning innan man sträcker sig efter objektet fästs blicken på ytterligare områden såsom golvet och bordet som objektet placerats på.
155

Provisioning Strategies for Transparent Optical Networks Considering Transmission Quality, Security, and Energy Efficiency

Jirattigalachote, Amornrat January 2012 (has links)
The continuous growth of traffic demand driven by the brisk increase in number of Internet users and emerging online services creates new challenges for communication networks. The latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build Transparent Optical Networks (TONs) which are expected to be able to satisfy this rapidly growing capacity demand. Moreover, with the ability of TONs to transparently carry the optical signal from source to destination, electronic processing of the tremendous amount of data can be avoided and optical-to-electrical-to-optical (O/E/O) conversion at intermediate nodes can be eliminated. Consequently, transparent WDM networks consume relatively low power, compared to their electronic-based IP network counterpart. Furthermore, TONs bring also additional benefits in terms of bit rate, signal format, and protocol transparency. However, the absence of O/E/O processing at intermediate nodes in TONs has also some drawbacks. Without regeneration, the quality of the optical signal transmitted from a source to a destination might be degraded due to the effect of physical-layer impairments induced by the transmission through optical fibers and network components. For this reason, routing approaches specifically tailored to account for the effect of physical-layer impairments are needed to avoid setting up connections that don’t satisfy required signal quality at the receiver. Transparency also makes TONs highly vulnerable to deliberate physical-layer attacks. Malicious attacking signals can cause a severe impact on the traffic and for this reason proactive mechanisms, e.g., network design strategies, able to limit their effect are required. Finally, even though energy consumption of transparent WDM networks is lower than in the case of networks processing the traffic at the nodes in the electronic domain, they have the potential to consume even less power. This can be accomplished by targeting the inefficiencies of the current provisioning strategies applied in WDM networks. The work in this thesis addresses the three important aspects mentioned above. In particular, this thesis focuses on routing and wavelength assignment (RWA) strategies specifically devised to target: (i) the lightpath transmission quality, (ii) the network security (i.e., in terms of vulnerability to physical-layer attacks), and (iii) the reduction of the network energy consumption. Our contributions are summarized below. A number of Impairment Constraint Based Routing (ICBR) algorithms have been proposed in the literature to consider physical-layer impairments during the connection provisioning phase. Their objective is to prevent the selection of optical connections (referred to as lightpaths) with poor signal quality. These ICBR approaches always assign each connection request the least impaired lightpath and support only a single threshold of transmission quality, used for all connection requests. However, next generation networks are expected to support a variety of services with disparate requirements for transmission quality. To address this issue, in this thesis we propose an ICBR algorithm supporting differentiation of services at the Bit Error Rate (BER) level, referred to as ICBR-Diff. Our approach takes into account the effect of physical-layer impairments during the connection provisioning phase where various BER thresholds are considered for accepting/blocking connection requests, depending on the signal quality requirements of the connection requests. We tested the proposed ICBR-Diff approach in different network scenarios, including also a fiber heterogeneity. It is shown that it can achieve a significant improvement of network performance in terms of connection blocking, compared to previously published non-differentiated RWA and ICBR algorithms.  Another important challenge to be considered in TONs is their vulnerability to physical-layer attacks. Deliberate attacking signals, e.g., high-power jamming, can cause severe service disruption or even service denial, due to their ability to propagate in the network. Detecting and locating the source of such attacks is difficult, since monitoring must be done in the optical domain, and it is also very expensive. Several attack-aware RWA algorithms have been proposed in the literature to proactively reduce the disruption caused by high-power jamming attacks. However, even with attack-aware network planning mechanisms, the uncontrollable propagation of the attack still remains an issue. To address this problem, we propose the use of power equalizers inside the network nodes in order to limit the propagation of high-power jamming attacks. Because of the high cost of such equipment, we develop a series of heuristics (incl. Greedy Randomized Adaptive Search Procedure (GRASP)) aiming at minimizing the number of power equalizers needed to reduce the network attack vulnerability to a desired level by optimizing the location of the equalizers. Our simulation results show that the equalizer placement obtained by the proposed GRASP approach allows for 50% reduction of the sites with the power equalizers while offering the same level of attack propagation limitation as it is possible to achieve with all nodes having this additional equipment installed. In turn, this potentially yields a significant cost saving.    Energy consumption in TONs has been the target of several studies focusing on the energy-aware and survivable network design problem for both dedicated and shared path protection. However, survivability and energy efficiency in a dynamic provisioning scenario has not been addressed. To fill this gap, in this thesis we focus on the power consumption of survivable WDM network with dynamically provisioned 1:1 dedicated path protected connections. We first investigate the potential energy savings that are achievable by setting all unused protection resources into a lower-power, stand-by state (or sleep mode) during normal network operations. It is shown that in this way the network power consumption can be significantly reduced. Thus, to optimize the energy savings, we propose and evaluate a series of energy-efficient strategies, specifically tailored around the sleep mode functionality. The performance evaluation results reveal the existence of a trade-off between energy saving and connection blocking. Nonetheless, they also show that with the right provisioning strategy it is possible to save a considerable amount of energy with a negligible impact on the connection blocking probability. In order to evaluate the performance of our proposed ICBR-Diff and energy-aware RWA algorithms, we develop two custom-made discrete-event simulators. In addition, the Matlab program of GRASP approach for power equalization placement problem is implemented. / <p>QC 20120508</p>
156

新動力?新城市?綠色共識下新能源汽車與上海嘉定區產城融合模式的發展 / New Motion? New City? The Development of New Energy Vehicles and the City-Industry Integration Model in Jiading Under Green Consensus

王藝, Wang, Yi Unknown Date (has links)
環境惡化與經濟下行的壓力,讓中國各級政府必須尋求一條有別於過去的集約、創新、綠色的發展道路。在這種背景下,類似新能源汽車等兼具節能環保、產業轉型的一批戰略性新興產業開始興起;而地方在承接與發展這些產業時,則傾向於將產業的發展同地方的城市化相結合,採行「以產業為動力,以新城為依託,以生態為源泉」的產城融合模式。 本文通過實地田野調查對上海市嘉定區發展新能源汽車產業的案例進行研究並認為:地方政府為了應對外部發展環境的變化,選擇「把握發展主動權」引入新能源汽車產業,但其實質為把握地方不變的關鍵性資源,即土地開發權。憑藉新能源汽車所帶來的產業不確定性與「綠色共識」下發展正當性的橋接,地方政府獲得了更大的行為自主性與容錯空間,得以透過產業基地與國際示範區的建立帶動地方整體的空間轉型,進而謀取短期的土地開發利益;但產業發展的長期目標卻在這樣的過程中被推遲乃至消解。經由以上案例,本研究將揭示「產城融合」「城」大於「產」之本質,並深入討論綠色發展成為主流論述之下中國地方發展模式的轉變。 / Under the pressure of environmental deterioration and economic downturn, Chinese government have to seek to find a more intensified, innovative and environmental friendly (green) path to development, which differs from the inherent one. As a result, strategic emerging industries like New Energy Vehicles (NEVs) that bear the target of energy saving, environmental protection and industrial transformation start rising. For local governments who take main responsibility of acting, the way how they implement is to combine the industrial development with local urbanization process, which could be called as City-Industry Integration Model. This paper research the development of New Energy Vehicles in Jiading District, Shanghai Municipality and argues that in order to adapt to the changes of external conditions, local government chooses to “grasp the developmental initiative” to introduce the NEVs industry. However, the essence of the action is to grasp the changeless local key resources, which is the land development rights. Rely on the industrial uncertainty and the bridging of developmental legitimacy under Green Consensus, more autonomy and fault-tolerant space has been obtained by local government. Moreover, local officials could implement spatial transformation through the construction of industrial base and international demonstration area, and then gain short-term land development interests, which is in the cost of long-standing goal of industry booming. Overall, this research would reveal the fact that urbanization occupies a larger proportion than industrial development in the City-Industry Integration Model, and discuss the transformation of local developmental model in China under the new mainstream discourse of sustainable development.
157

Optimisation de la précision de calcul pour la réduction d'énergie des systèmes embarqués

Nguyen, Hai-Nam 16 December 2011 (has links) (PDF)
Cette thèse s'inscrit dans le contexte de la forte augmentation du débit et de la puissance de calcul des systèmes de télécommunications. Cette augmentation entraîne une consommation d'énergie importante et réduit la durée de batterie, ce qui est primordiale pour un système embarqué. Nous proposons des mécanismes permettant de réduire la consommation d'énergie dans un système embarqué, plus particulièrement dans un terminal mobile sans fil. L'implantation efficace des algorithmes de traitement numérique du signal dans les systèmes embarqués requiert l'utilisation de l'arithmétique virgule fixe afin de satisfaire des contraintes de coût, de consommation et d'encombrement. Dans les approches classiques, la largeur des données et des calculs est considérée au pire cas lors de la détermination des spécifications afin qu'elles soient satisfaites dans tout les cas. Nous proposons une approche d'adaptation dynamique, permettant de changer la spécification en fonction de l'environnement (par exemple les conditions d'un canal de transmission) avec pour objectif de réduire la consommation d'énergie dans certaines conditions. Tout d'abord, la relation entre la puissance de bruit de quantification et le taux d'erreur binaire du système en fonction du bruit au récepteur est établie pour une chaîne de transmission QPSK. Ce résultat est appliqué dans la technique d'accès multiple par répartition de codes en séquence directe (DS-CDMA). Parmi plusieurs systèmes de télécommunications utilisant la technique DS-CDMA, nous montrons comment adapter dynamiquement la précision de calcul d'un récepteur 3G WCDMA. La conversion en virgule fixe nécessite un algorithme d'optimisation combinatoire pour l'optimisation des largeurs des opérateurs sous une contrainte de précision. La deuxième axe de ces travaux de thèse concerne l'étude d'algorithmes d'optimisation adaptés au problème de l'optimisation des largeurs de données. Nous proposons de nouveaux algorithmes pour les problèmes à une seule contrainte ou à une suite des contraintes correspondant à différents niveaux de précision pour les systèmes auto-adaptatifs. Le résultat des algorithmes génétiques multi-objectifs, sous forme d'une frontière de Pareto, permet d'obtenir la largeur correspondant à chaque niveau du bruit de quantification. Une version améliorée des algorithmes génétiques combinée avec l'élitisme et la recherche tabou est proposée. En plus, nous proposons d'appliquer GRASP, un algorithme de recherche locale stochastique permettant de trouver le résultat dans un temps plus faible en comparaison avec les algorithmes génétiques.
158

An electrophysiological examination of visuomotor activity elicited by visual object affordances

Dixon, Thomas Oliver January 2016 (has links)
A wide literature of predominantly behavioural experiments that use Stimulus Response Compatibility (SRC) have suggested that visual action information such as object affordance yields rapid and concurrent activation of visual and motor brain areas, but has rarely provided direct evidence for this proposition. This thesis examines some of the key claims from the affordance literature by applying electrophysiological measures to well established SRC procedures to determine the verities of the behavioural claims of rapid and automatic visuomotor activation evoked by viewing affording objects. The temporal sensitivity offered by the Lateralised Readiness Potential and by visual evoked potentials P1 and N1 made ideal candidates to assess the behavioural claims of rapid visuomotor activation by seen objects by examining the timecourse of neural activation elicited by viewing affording objects under various conditions. The experimental work in this thesis broadly confirms the claims of the behavioural literature however it also found a series of novel results that are not predicted by the behavioural literature due to limitations in reaction time measures. For example, while different classes of affordance have been shown to exert the same behavioural facilitation, electrophysiological measures reveal very different patterns of cortical activation for grip-type and lateralised affordances. These novel findings question the applicability of the label ‘visuomotor’ to grip-type affordance processing and suggest considerable revision to models of affordance. This thesis also offers a series of novel and surprising insights into the ability to dissociate afforded motor activity from behavioural output, into the relationship between affordance and early visual evoked potentials, and into affordance in the absence of the intention to act. Overall, this thesis provides detailed suggestions for considerable changes to current models of the neural activity underpinning object affordance.
159

Natural Hand Based Interaction Simulation using a Digital Hand

Vipin, J S January 2013 (has links) (PDF)
The focus of the present work is natural human like grasping, for realistic performance simulations in digital human modelling (DHM) environment. The performance simulation for grasping in DHM is typically done through high level commands to the digital human models (DHMs). This calls for a natural and unambiguous scheme to describe a grasp which would implicitly accommodate variations due to the hand form, object form and hand kinematics. A novel relational description scheme is developed towards this purpose. The grasp is modelled as a spatio-temporal relationship between the patches (a closed region on the surface) in the hand and the object. The task dependency of the grasp affects only the choice of the relevant patches. Thus, the present scheme of grasp description enables a human like grasp description possible. Grasping can be simulated either in an interactive command mode as discussed above or in an autonomous mode. In the autonomous mode the patches have to be computed. It is done using a psychological concept, of affordance. This scheme is employed to select a tool from a set of tools. Various types of grasps a user may adopt while grasping a spanner for manipulating a nut is simulated. Grasping of objects by human evolves through distinct naturally occurring phases, such as re-oreintation, transport and preshape. Hand is taken to the object ballpark using a novel concept of virtual object. Before contact establishment hand achieves the shape similar to the global shape of the object, called preshaping. Various hand preshape strategies are simulating using an optimization scheme. Since the focus of the present work is human like grasping, the mechanism which drives the DHMs should also be anatomically pertinent. A methodology is developed wherein the hand-object contact establishment is done based on the anatomical observation of logarithmic spiral pattern during finger flexion. The effect of slip in presence of friction has been studied for 2D and 3D object grasping endeavours and a computational generation of the slip locus is done. The in-grasp slip studies are also done which simulates the finger and object response to slip. It is desirable that the grasping performance simulations be validated for diverse hands that people have. In the absence of an available database of articulated bio-fidelic digital hands, this work develops a semi-automatic methodology for developing subject specific hand models from a single pose 3D laser scan of the subject's hand. The methodology is based on the clinical evidence that creases and joint locations on human hand are strongly correlated. The hand scan is segmented into palm, wrist and phalanges, both manually and computationally. The computational segmentation is based on the crease markings in the hand scan, which is identified by explicitly painting them using a mesh processing software by the user. Joint locations are computed on this segmented hand. A 24 dof kinematic structure is automatically embedded into the hand scan. The joint axes are computed using a novel palm plane normal concept. The computed joint axes are rectified using the convergence, and intra-finger constraints. The methodology is significantly tolerant to the noise in the scan and the pose of the hand. With the proposed methodology articulated, realistic, custom hand models can be generated. Thus, the reported work presents a geometric framework for comprehensive simulation of grasping performance in a DHM environment.
160

Optimización de la localización de hidrantes multiusuario y trazado de redes de riego a presión mediante la utilización de SIG.

González Pavón, César 25 April 2023 (has links)
[ES] Un aprovechamiento racional y ajustado de los recursos hídricos disponibles en el regadío implica la necesidad de disponer de infraestructuras que mediante conducciones a presión permitan llevar desde captación hasta la planta los volúmenes requeridos. Los sistemas de riego a presión, tanto a nivel colectivo como en parcela, permiten un alto control sobre el agua aplicada y garantizan una alta eficiencia de aplicación. La adopción de estos sistemas de riego ha llevado en los últimos 30 años a la construcción y puesta en marcha de numerosas redes colectivas de riego a presión. En el marco mediterráneo donde el modelo productivo se basa en una agricultura intensiva de parcelas de tamaño pequeño y medio (superficies medias no superiores a 0,5 ha), el sistema de distribución del agua desde la red a la parcela se realiza normalmente a través de hidrantes denominados multiusuario. La localización y capacidad hidráulica de estos elementos es un tema poco estudiado hasta la fecha. Tradicionalmente su localización y definición de los elementos que lo componen ha corrido a cargo de la propia experiencia en estos campos de los ingenieros, desconociendo en muchos casos como afectan estos parámetros al funcionamiento final de la instalación y a los costes que supone dicha inversión. Esta Tesis aborda el estudio de estos aspectos con el objetivo de obtener una metodología de cálculo basada en la utilización de los SIG que optimice tanto la ubicación de los hidrantes como el trazado de conducciones entre los mismos desde el punto de alimentación. Como punto de partida, se definió la capacidad hidráulica de los mismos en cuanto a caudal y número de tomas que pueden abastecer, dando unas recomendaciones basadas en estudios hidráulicos de las características finales que deben tener los mismos en cada caso y de las tomas individuales a parcela. Seguidamente, se abordó la problemática de la localización, relacionada directamente con el anterior punto. En este caso, mediante la utilización de distintas herramientas de geoprocesos que ofrecen los softwares basados en SIG, se obtuvieron las localizaciones que minimizan tanto los costes energéticos como los de inversión. Finalmente, obtenida la ubicación, se estableció el trazado de las conducciones desde la toma hasta cada uno de los hidrantes. En este caso, los criterios a tener en cuenta fueron función del tipo de vía por el que se pretenden trazar (camino rural, carretera, cauce, etc) llevándose a cabo mediante la elaboración de un mapa ráster de resistencias donde la solución óptima fue aquella que menos resistencia acumulada ofrecía. Para su elaboración se requirió del apoyo de metodologías de análisis Multicriterio como AHP. Toda la metodología de trabajo fue aplicada sobre doce casos de estudio reales y se comparará con el diseño de ingenieros proyectistas especialistas en el campo de la modernización de regadíos. Los resultados obtenidos mediante el uso de la metodología planteada arrojaron unos ahorros en los costes totales de hasta el 15 % respecto al dimensionado externo. En todos ellos se obtuvo la misma tendencia, pese a obtener mayor número de hidrantes multiusuario, se redujeron los costes totales de instalación de la red. Como conclusión puede decirse que la metodología aportada redujo considerablemente los costes y planteó unos criterios objetivos a la hora del diseño y dimensionado de las redes. De este modo se redujo la subjetividad aportada por el proyectista. / [CA] Un aprofitament racional i ajustat dels recursos hídrics disponibles en el regadiu implica la necessitat de disposar d'infraestructures que mitjançant conduccions a pressió permeten portar des de captació fins a la planta els volums requerits. Els sistemes de reg a pressió, tant a nivell col·lectiu com en parcel·la, permeten un alt control sobre l'aigua aplicada i garanteixen una alta eficiència d'aplicació. L'adopció d'aquests sistemes de reg ha portat en els últims 30 anys la construcció i posada en marxa de nombroses xarxes col·lectives de reg a pressió. En el marc mediterrani on el model productiu es basa en una agricultura intensiva de parcel·les de grandària petita i mitjana (superfícies mitjanes no superiors a 0,5 ha), el sistema de distribució de l'aigua des de la xarxa a la parcel·la es realitza normalment a través d'hidrants denominats multiusuari. La localització i capacitat hidràulica d'aquests elements és un tema poc estudiat fins hui. Tradicionalment la seua localització i definició dels elements que ho componen ha sigut a càrrec de la pròpia experiència en aquests camps dels enginyers, desconeixent en molts casos com afecten aquests paràmetres al funcionament final de la instal·lació i als costos que suposa aquesta inversió. Aquesta Tesi aborda l'estudi d'aquests aspectes amb l'objectiu d'obtindre una metodologia de càlcul basada en la utilització dels SIG que optimitze tant la ubicació dels hidrants com el traçat de conduccions entre els mateixos des del punt d'alimentació. Com a punt de partida, es va definir la capacitat hidràulica dels mateixos quant a cabal i nombre de tomes que poden proveir, donant unes recomanacions basades en estudis hidràulics de les característiques finals que han de tindre els mateixos en cada cas i de les preses individuals a parcel·la. Seguidament, es va abordar la problemàtica de la localització, relacionada directament amb l'anterior punt. En aquest cas, mitjançant la utilització de diferents eines de geoprocesos que ofereixen els softwares basats en SIG, es van obtindre les localitzacions que minimitzen tant els costos energètics com els d'inversió. Finalment, obtinguda la ubicació, es va establir el traçat de les conduccions des de la presa fins cadascun dels hidrants. En aquest cas, els criteris a tindre en compte van ser funció del tipus de via pel qual es pretenen traçar (camí rural, carretera, llit, etc) duent-se a terme mitjançant l'elaboració d'un mapa ráster de resistències on la solució òptima va ser aquella que menys resistència acumulada oferia. Per a la seua elaboració es va requerir del suport de metodologies d'anàlisi Multicriteri com AHP. Tota la metodologia de treball va ser aplicada sobre dotze casos d'estudi reals i va comparar amb el disseny d'enginyers projectistes especialistes en el camp de la modernització de regadius. Els resultats obtinguts mitjançant l'ús de la metodologia plantejada van llançar uns estalvis en els costos totals de fins al 15% respecte al dimensionament extern. En tots ells es va obtindre la mateixa tendència, malgrat obtindre major nombre d'hidrants multiusuari, es van reduir els costos totals d'instal·lació de la xarxa. Com a conclusió pot dir-se que la metodologia aportada va reduir considerablement els costos i va plantejar uns criteris objectius a l'hora del disseny i dimensionament de les xarxes. D'aquesta manera es va reduir la subjectivitat aportada pel projectista. / [EN] Rational and adjusted use of the water resources available in irrigation implies the need to have infrastructures that, by means of pressure pipes, can carry out the required volumes from the catchment to the plant. Pressurized irrigation systems, both at the collective level and on the plot, allow high control over the water applied and guarantee high application efficiency. The adoption of these irrigation systems has led in the last 30 years to the construction and start-up of numerous collective pressurized irrigation networks. In the Mediterranean framework, where the production model is based on intensive agriculture of small and medium-sized plots (average surfaces not exceeding 0.5 ha), the water distribution system from the network to the plot is normally carried out through of -called multi-user hydrants. The location and hydraulic capacity of these elements is a subject little studied to date. Traditionally, its location and definition of the elements that compose it have been carried out by the engineers' own experience in these fields, in many cases unaware of how these parameters affect the final operation of the installation and the costs involved in said investment. This thesis deals with the study of these aspects to obtain a calculation methodology based on the use of GIS that optimizes both the location of the hydrants and the layout of the pipes between them from the point of supply. As a starting point, their hydraulic capacity was defined in terms of flow rate and number of intakes they can supply, giving recommendations based on hydraulic studies of the final characteristics that they should have in each case and of the individual intakes on a plot. Next, the problem of location, directly related to the previous point, was addressed. In this case, by using different geoprocessing tools offered by GIS-based software, locations that minimize both energy and investment costs were obtained. Finally, once the location was obtained, the layout of the pipes from the intake to each of the hydrants was established. In this case, the criteria to be taken into account were a function of the type of road along which it is intended to be traced (rural road, highway, riverbed, etc.) carried out by preparing a raster map of resistances where the optimal solution was that that offered less accumulated resistance. For its elaboration, the support of Multicriteria analysis methodologies such as AHP was required. The entire work methodology was applied to twelve real case studies and will be compared with the design of specialist project engineers in the field of irrigation modernization. The results obtained through the use of the proposed methodology showed savings in total costs of up to 15% compared to external dimensioning. The same trend was obtained in all of them, despite obtaining a greater number of multi-user hydrants, the total costs of installing the network were reduced. In conclusion, it can be said that the methodology provided considerably reduced costs and proposed objective criteria when designing and sizing the networks. In this way, the subjectivity provided by the designer was reduced. / González Pavón, C. (2023). Optimización de la localización de hidrantes multiusuario y trazado de redes de riego a presión mediante la utilización de SIG [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192926

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