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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.
21

Modified Network Simplex Method to Solve a Sheltering Network Planning and Management Problem

Li, Lingfeng 09 December 2011 (has links)
This dissertation considers sheltering network planning and operations for natural disaster preparedness and responses with a two-stage stochastic program. The first phase of the network design decides the locations, capacities and held resources of new permanent shelters. Both fixed costs for building a new permanent shelter and variable costs based on capacity are considered. Under each disaster scenario featured by the evacuee demand and transportation network condition, the flows of evacuees and resources to shelters, including permanent and temporary ones, are determined in the second stage to minimize the transportation and shortage/surplus costs. Typically, a large number of scenarios are involved in the problem and cause a huge computational burden. The L-shaped algorithm is applied to decompose the problem into the scenario level with each sub-problem as a linear program. The Sheltering Network Planning and Operation Problem considered in this dissertation also has a special structure in the second-stage sub-problem that is a minimum cost network flow problem with equal flow side constraints. Therefore, the dissertation also takes advantages of the network simplex method to solve the response part of the problem in order to solve the problem more efficiently. This dissertation investigates the extending application of special minimum cost equal flow problem. A case study for preparedness and response to hurricanes in the Gulf Coast region of the United States is conducted to demonstrate the usage of the model including how to define scenarios and cost structures. The numerical experiment results also verify the fast convergence of the L-shaped algorithm for the model.
22

Multi-modal Public Transport Network Design Method

Liu, Mingui January 2023 (has links)
With the rapid development of industrialization and urbanization, industrial development and population growth drive the expansion of urban space, urban transportation demand shows the characteristics of spatial decentralization and diversification, and transportation travelers' requirements for mobility, accessibility, and comfort of transportation travel services are enhanced. Mobility on demand (MoD) services such as DiDi and Uber are new modes of public transportation, bringing many new opportunities and challenges. MoD travel services, shared bicycles, and other complementary public transport modes are rapidly developing in the "Internet +" environment, serving the "one mile" before and after the residents' travel. MoD technologies play an important role as a feeder to the main public transportation lines, helping to increase public transportation patronage and improve the speed of travel for residents. In this context, the study aims to develop a multi-modal public transportation system network design methodology to provide better operational coordination between different modes of transportation and to provide faster travel services. In order to promote better coordination between different transportation modes and to provide theoretical and methodological support for the development of a multi-modal public transportation system network design system, a bi-level planning model for this problem is first constructed. The upper-level planning model is used to minimize the total travel time and cost of passengers and the economic cost of public transportation operators, and to decide which bus lines to operate, the structure of bus lines, and the frequency of operating bus lines; the lower-level operating model is used to assign passengers to make travel mode choices and to carry out traffic distribution of the public transportation network based on the minimum number of interchanges. Then, based on this bi-level planning model, an improved genetic algorithm is developed to solve the upper-level public transportation network planning problem, in which the algorithm for passenger flow allocation in the lower-level planning model is nested in the genetic algorithm.  Finally, the developed methodology is validated for the benchmark Mandl network design by comparing with the traditional public transportation network. The results show that the multi-modal public transportation network can effectively reduce passenger travel time compared with the traditional public transportation network at similar costs. Finally, we applied the network design method for the Barkarby area in the north of Stockholm, Sweden. The results show that it is appropriate to allocate mobility on demand vehicles in this area. The constructed model and the proposed algorithm are scientifically valid and can provide theoretical methodological reference and decision support for engineering practice.
23

Optimising BFWA networks

Wade, A. A. January 2005 (has links)
No description available.
24

Otimização multi-nível para projeto de redes híbridas (ópticas e sem fio) para implementação de cidades inteligentes

Barth, Márcio Joel 25 November 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2017-03-16T12:00:50Z No. of bitstreams: 1 Márcio Joel Barth_.pdf: 2194609 bytes, checksum: 0c1a7161c69d20257d7c5bbfd9340a30 (MD5) / Made available in DSpace on 2017-03-16T12:00:50Z (GMT). No. of bitstreams: 1 Márcio Joel Barth_.pdf: 2194609 bytes, checksum: 0c1a7161c69d20257d7c5bbfd9340a30 (MD5) Previous issue date: 2016-11-25 / PROCERGS - Companhia de Processamento de Dados do Estado do Rio Grande do Sul / Estudos sobre infraestrutura de redes têm sido realizados e aplicados em várias indústrias de serviços, tais como telecomunicações, distribuição de energia, água e mais recentemente para atendimento das necessidades de infraestrutura de cidades inteligentes que requerem soluções de infraestrutura híbridas. Entretanto, o planejamento de infraestrutura de redes em vários níveis e também com máxima cobertura, é um problema em aberto, pois, geralmente, a literatura apresenta soluções nas quais somente um nível é processado e os problemas são solucionados de forma individual. O planejamento da distribuição e conexão de equipamentos em vários níveis de uma infraestrutura de rede é uma tarefa árdua, pois é necessário avaliar a quantidade e a melhor distribuição geográfica de equipamentos em cada nível da rede, ou seja, no nível 1 são avaliadas as necessidades que atendem diretamente aos clientes, já o nível 2 atenderá as necessidades do nível 1, e que também sejam observados os níveis adjacentes. O resultado que um projetista obtém ao realizar manualmente o planejamento torna-se superficial, devido a inviabilidade de analisar todos os cenários que podem ser obtidos com as informações de quantidades e de distribuição dos equipamentos na região do projeto. Ainda mais complexo é alterar um nível já projetado, visto que é necessário rever a quantidade, localização e caminho entre os equipamentos, refazendo os cálculos do nível alterado, e, consequentemente, o nível anterior e todos os níveis subsequentes. Esta pesquisa apresenta um algoritmo baseado na metaheuristica de colônia de formigas, capaz de procurar por uma solução para o planejamento de infraestrutura de redes híbridas multiníveis capacitadas, resolvendo o problema de recobrimento e planejamento de redes de forma conjunta e obtendo resultados melhores na ordem de 20% no custo da solução quando comparado com outra solução que utiliza algoritmo genético. / Studies on network infrastructure have been used and applied in various service industries, such as telecommunications, power distribution, water, and more recently to meet the smart city infrastructure needs, that require hybrid infrastructure solutions. However, planning multilevel network infrastructures and also with maximum coverage is an open problem, since the literature generally presents solutions in which only one level is processed and problems solved individually. The distribution plan and equipment connection at various levels of a network infrastructure is a ardous task, it is necessary to evaluate the quantity and better geographical distribution of equipment at each level of the network, ie at level 1 are evaluated needs to meet directly to customers, since the level 2 from level 1 will meet the needs, and the adjacent levels are also observed. The result that a designer gets to manually carry out the planning becomes shallow due to impossibility of analyzing all scenarious that can be obtained with the amounts and distribution of information equipment in the project region. Even more complex is change a level already designed, since it is necessary to review the amount, location and path between devices, redoing the calculations of the modified level, and hence the previous level and all subsequent levels. This research presents an algorithm based on ant colony metaheuristics, capable of searching for a solution to the infrastructure planning of hybrid multilevel networks, solving the network planning and coverage problem together and obtaining better results in the order of 20% on the cost of the solution when compared to another solution using genetic algorithm.
25

Efficient in-network content distribution : wireless resource sharing, network planning, and security / Distribution efficace des contenus dans les réseaux : partage de ressources sans fil, planification et sécurité

Mangili, Michele 15 December 2015 (has links)
Au cours de ces dernières années, la quantité de trafic que les utilisateurs Internet produisent sur une base quotidienne a augmenté de façon exponentielle, principalement en raison du succès des services de streaming vidéo, tels que Netflix et YouTube. Alors que les réseaux de diffusion de contenu (Content-Delivery Networks, CDN) sont la technique standard utilisée actuellement pour servir les demandes des utilisateurs, la communauté scientifique a formulé des propositions connues sous le nom de Content-Centric Networks (CCN) pour changer la pile de protocoles réseau afin de transformer Internet en une infrastructure de distribution de contenu. Dans ce contexte, cette thèse de doctorat étudie des techniques efficaces pour la distribution de contenu numérique en tenant compte de trois problèmes complémentaires : 1) Nous considérons le scénario d’un réseau hétérogène sans fil, et nous formulons un mécanisme pour motiver les propriétaires des points d’accès à partager leur capacité WiFi et stockage cache inutilisés, en échange d’une contribution économique.2) Nous étudions le problème centralisé de planification du réseau en présence de caches distribuées et (I) nous analysons la migration optimale du réseau à CCN; (II) nous comparons les bornes de performance d’un réseau CDN avec ceux d’un CCN, et (III) nous considérons un réseau CDN virtualisé et étudions le problème stochastique de planification d’une telle infrastructure.3) Nous considérons les implications de sécurité sur le contrôle d’accès et la traçabilité, et nous formulons ConfTrack-CCN, une extension deCCN utilisée pour garantir la confidentialité, traçabilité et l’évolution de la politique d’accès, en présence de caches distribuées. / In recent years, the amount of traffic requests that Internet users generate on a daily basis has increased exponentially, mostly due to the worldwide success of video streaming services, such as Netflix and YouTube. While Content-Delivery Networks (CDNs) are the de-facto standard used nowadays to serve the ever increasing users’ demands, the scientific community has formulated proposals known under the name of Content-Centric Networks (CCN) to change the network protocol stack in order to turn the network into a content distribution infrastructure. In this context this Ph.D. thesis studies efficient techniques to foster content distribution taking into account three complementary problems:1) We consider the scenario of a wireless heterogeneous network, and we formulate a novel mechanism to motivate wireless access point owners to lease their unexploited bandwidth and cache storage, in exchange for an economic incentive.2) We study the centralized network planning problem and (I) we analyze the migration to CCN; (II) we compare the performance bounds for a CDN with those of a CCN, and (III) we take into account a virtualized CDN and study the stochastic planning problem for one such architecture.3) We investigate the security properties on access control and trackability and formulate ConfTrack-CCN: a CCN extension to enforce confidentiality, trackability and access policy evolution in the presence of distributed caches.
26

Formelle und informelle Öffentlichkeitsbeteiligung in Infrastrukturplanungs- und Genehmigungsverfahren für Hoch- und Höchstspannungsnetze

Zirke, Daniel 09 November 2021 (has links)
Der europarechtlich vorgeprägte und national stark ausdifferenzierte Bedarfsplanungs- und Genehmigungsablauf für Hoch- und Höchstspannungsleitungsvorhaben ist durch ein umfassendes Beteiligungsregime zu Gunsten der Öffentlichkeit ausgestaltet. Im Rahmen der gegenständlichen Arbeit wurden sowohl die formellen als auch die informellen Beteiligungsmöglichkeiten der Öffentlichkeit analysiert, klassifiziert, kritisch hinterfragt und hinsichtlich der verschiedentlich anwendbaren normativen Vorgaben miteinander verglichen. Hierbei haben unter anderem europarechtlich das Vierte Energiebinnenmarktpaket aus den Jahren 2018 und 2019, national das Gesetz zur Beschleunigung des Energieleitungsausbaus aus dem Jahr 2019 und das Planungssicherstellungsgesetz aus dem Jahr 2020 sowie föderal das Umweltverwaltungsgesetz aus dem Jahr 2014 besondere Berücksichtigung gefunden. Insgesamt konnte die aktuelle Gesetzeslage, Rechtsprechung und Literatur bis Ende Juni 2020 in die vorliegende Untersuchung eingearbeitet werden.:Teil 1: Einführung Teil 2: Grundlagen der Öffentlichkeitsbeteiligung im Netzausbau Teil 3: Öffentlichkeitsbeteiligung im Rahmen der Bedarfsplanung Teil 4: Öffentlichkeitsbeteiligung im Rahmen der Korridor- und Trassenplanung Teil 5: (Temporäre) Wirkungen des PlanSiG auf die Öffentlichkeitsbeteiligung Teil 6: Gesamtbetrachtung zur Verbesserung des Beteiligungsregimes / The planning and approval process for high and extra high voltage power line pro- jects, which is predefined by European law and differentiated by German law, is designed in favour of the public through a comprehensive participation regime. In the context of this work, both the formal and the informal opportunities for public participation were analysed, classified, critically questioned and compared with one another in terms of the various normative requirements. Among other things, the Fourth European Internal Energy Market Package from 2018 and 2019, the national law to accelerate the expansion of power lines from 2019, and the law to ensure proper planning and approval procedures from 2020 as well as the federal law to standardise environmental administration law and to strengthen public participation in the environmental field from 2014 have been given special consideration. Overall, the current legal situation, the case law and the literature until the end of June 2020 have been incorporated into the present study.:Teil 1: Einführung Teil 2: Grundlagen der Öffentlichkeitsbeteiligung im Netzausbau Teil 3: Öffentlichkeitsbeteiligung im Rahmen der Bedarfsplanung Teil 4: Öffentlichkeitsbeteiligung im Rahmen der Korridor- und Trassenplanung Teil 5: (Temporäre) Wirkungen des PlanSiG auf die Öffentlichkeitsbeteiligung Teil 6: Gesamtbetrachtung zur Verbesserung des Beteiligungsregimes
27

Protection-based Distributed Generation Penetration Limits on MV feeders - Using Machine Learning

Nxumalo, Emmanuel 11 March 2022 (has links)
The rise of disruptive technologies and the rapid growth of innovative initiatives have led to a trend of decentralization, deregulation, and distribution of regulated/centralized services. As a result, there is an increasing number of requests for the connection of distributed generators to distribution networks and the need for power utilities to quickly assess the impacts of distributed generators (DGs) to keep up with these requests. Grid integration of DGs brings about protection issues. Current protection systems were not designed for bi-directional power flow, thus the protective devices in the network lose their ability to perform their main functions. To mitigate the impact of distributed generation (DG), some standards and policies constrain the number of DG that can be connected to the distribution network. The problem with these limits is that they are based only on overload and overvoltage, and do not adequately define the DG size/threshold before the occurrence of a protection issue (NRS 097-2-3). The other problem with distributed generation is the vast difference in the technology, location, size, connection sequence, and protection scheme requirements which results in future DG network planning inadequacies – The Network DG Planning Dilemma. To determine the amount of DG to connect to the network, a detailed analysis is required which often involves the use of a simulation tool such as DIgSILENT to model the entire network and perform load flow studies. Modelling networks on DIgSILENT is relatively easy for simple networks but becomes time-consuming for complex, large, and real networks. This brings about a limitation to this method, planning inadequacies, and longer connection approval periods. Thus, there is a need for a fast but accurate system-wide tool that can assess the amount of DG that can be connected to a network. This research aims to present a technique used for calculating protection-based DG penetration limits on MV networks and develop a model to determine medium voltage opportunity network maps. These maps indicate the maximum amount of DG that can be connected to a network without the need for major protection scheme changes in South Africa. The approach to determining protection-based penetration limits is based on supervised machine learning methods. The aim is to rely on protection features present in the distribution network data i.e. fault level, Inverse Definite Minimum Time (IDMT) curve, pick-up current settings, Time Multiplier Settings (TMS), calculated relay operating times and relay positions to see how the network responds at certain DG penetration levels (‘actual' relay operating times). The dataset represents carefully anonymized distribution networks with accepted protection philosophy applied. A supervised machine learning algorithm is applied after nontrivial data pre-processing through recommendation systems and shuffling. The planning dilemma is cast into three parts: the first part is an automated pattern classification (logistic regression for classification of protection miscoordination), the second part involves regression (predicting operating time after different levels of DG penetration), and the last part involves developing a recommendation system (where, when and how much photovoltaic (PV) DG will be connected). Gradient descent, which is an optimisation algorithm that iterates and finds optimal values of the parameters that correspond to the local or global minimum values of the cost function using calculus was used to measure the accuracy of each model's hypothesis function. The cost function (one half mean squared error) for the models that predict ‘actual' relay operating times before DG penetration, at 35%, 65%, and 75% DG penetration converged to values below 120, 20, 15, and 15 seconds2 , respectively, within the first 100 iterations. A high variance problem was observed (cross-validation error was high and training error was low) for the models that used all the network protection features as inputs. The cross-validation and training errors approached the desired performance of 0.3±0.1 for the models that had second-order polynomials added. A training accuracy of 91.30%, 73.91%, 82.61%, and a validation accuracy of 100%, 55.56%, 66.67% was achieved when classifying loss of coordination, loss of grading and desensitization, respectively. A high bias problem was observed (cross-validation error was high and training error was high) for the loss of grading classification (relay positions eliminated) model. When the models (horizontal network features) were applied to four MV distribution networks, loss of coordination was not predicted, the loss of grading model had one false positive and the de-sensitization model had one false negative. However, when the results were compared to the vertical analysis (comparing the operating times of upstream and downstream relays/reclosers), 28 points indicated a loss of coordination (2 at 35%, 1 at 65% and 25 at 75% DG penetration). Protection coordination reinforcements (against loss of grading and desensitization) were found to be a requirement for DG connections where the MV transformer circuit breaker TMS is between 0.5 and 1.1, and where the network fault level is between 650 and 800A. Distribution networks in affluent neighbourhoods similar to those around the Western CapeSomerset West area and Gauteng- Centurion area need to be reinforced to accommodate maximum DG penetration up to the limit of 75% of the After Diversity Maximum Demand (ADMD). For future work, the collection of more data points (results from detailed analytical studies on the impact of DG on MV feeders) to use as training data to solve the observed high variance problem is recommended. Also, modifying the model by adding upstream and downstream network features as inputs in the classification model to solve the high bias problem is recommended.
28

Contribution to the enhancement of the efficiency of IP-over-WDM networks by evaluating and attaining the limits of multilayer network planning / Contribution à l'amélioration de l'efficacité des réseaux IP sur WDM en évaluant et en dépassant les limites du dimensionnement multicouche

Nikolayev, Maksym 29 September 2014 (has links)
La quantité de données devant être transportée via les réseaux de cœur croit de près de 25% par an. Pour maîtriser les coûts, les différentes couches du réseau doivent mettre des informations en commun pour inclure de plus en plus de paramètres lors du dimensionnement du réseau. Cela s’appelle « dimensionnement multicouche ». Nous étudions le dimensionnement multicouche de réseaux statiques composés de deux couches utilisant la commutation en mode circuit (typiquement IP-sur-WDM). Nous proposons un modèle semi-analytique expliquant le comportement des algorithmes responsables de l’agrégation et du routage dans les deux couches. Ce cadre théorique permet de comparer les algorithmes de dimensionnement multicouche entre eux, mais aussi d’expliquer et d’améliorer leur efficience. Nous décrivons ensuite comment la contrainte de portée optique affecte les résultats d’un algorithme de dimensionnement multicouche. Enfin, nous expliquons comment ces résultats s'appliquent au dimensionnement des réseaux de nouvelle génération (dynamiques et hétérogènes en capacité optique) / The traffic passing through core networks grows by nearly 25% each year. To bring the costs under control, the different network layers of the network should work together to include more and more parameters during the network planning phase. This is called “multilayer network planning”. We study the multilayer network planning of static networks composed of two circuit switched layers (typically IP-over-WDM). We propose a semi-analytical model explaining the behavior of algorithms responsible for aggregation and routing in both layers. This theory allows comparing multilayer planning algorithms between them, but also explaining and enhancing their efficiency. We then describe the impact of the optical reach constraint in WDM networks on the results of a multilayer planning algorithm. Finally, we explain how these results apply to the design of future networks (dynamic and with heterogeneous optical layers)
29

Measuring the Influence That Components Have on Pedestrian Route Choice in Activated Alleys

Gross, Samuel Hirsher 01 June 2015 (has links) (PDF)
This paper explores how cities have integrated formal planning into improving public space. Through a review of literature on the topic, this the paper identifies the potential design has to renovate narrow streets and alleys, within the public right of way. By preforming an assessment of plans and programs, this paper identifies the common themes or components that have been used by planners, architects, and engineers to improve the urban environment for pedestrians. Based on this information, a pilot study was created to measure the influence the most common components have on pedestrian route choice. The results are then compared to the information gathered from the assessed plans and programs. Suggestions for expanding the pilot study and other recommendations are presented upon the conclusion of this report.
30

Разработка программного модуля построения диаграмм Ганта для решения задач планирования деятельности компании : магистерская диссертация / Development of a software module for constructing Gantt charts to solve the tasks of planning the company's activities

Кайгародов, А. И., Kaigarodov, A. I. January 2022 (has links)
В данной работе рассмотрен процесс разработки программного модуля для автоматизации задач планирования деятельности компании, а именно: построение диаграммы Ганта, расчет временных характеристик задач. Выполнен сравнительный анализ инструментов для разработки веб-приложений и платформ для сетевого планирования. Разработанный модуль рассчитывает даты раннего и позднего начала выполнения задачи, даты раннего и позднего окончания задачи, а также определяет резервы времени на ее выполнение, является кроссплатформенным и легко расширяемым. / In this paper, the process of developing a software module for automating the tasks of planning company's activities is considered, namely: building a Gantt chart, calculating time tasks characteristics. A comparative analysis of tools for the development of web applications and platforms for network planning is performed. The developed module calculates time parameters of the early and late start of a task, and time parameters of the early and late end of a task, and also determines the time reserves for its execution, the developed module is a cross-platform and also an easily extensible one.

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