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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.
11

CPU Load Control of LTE Radio Base Station

Larsson, Joachim January 2015 (has links)
A radio base station (RBS) may become overloaded if too many mobile devices communicate with it at the same time. This could happen at for instance sport events or in the case of accidents. To prevent CPU overload, the RBS is provided with a controller that adjusts the acceptance rate, the maximum number of connection requests that can be accepted per time interval. The current controller is tuned in real radio base stations and the procedure is both time consuming and expensive. This, combined with the fact that the mobile data usage is predicted to increase puts more pressure on today's system. Thus, there is a need to be able to simulate the system in order to suggest an alternative controller. In this thesis, an implementation of the system is developed in Matlab in order to simulate the RBS system load control behaviour. A CPU load model is estimated using system identification. The current version of the CPU load controller and an alternative PI CPU load controller are implemented. Both are evaluated on different test cases and this shows that it is possible to increase the performance of the system with the alternative CPU load controller, both in terms of lower amount of rejected connection requests and decreased CPU load overshoot.
12

AnÃlise dos impactos logÃsticos do Siscomex Carga em grandes empresas importadoras no Estado do Cearà / Logistics impacts of the Siscomex Carga in big import companies in the State of CearÃ

Paulo Henrique Neves de Carvalho Elias 10 August 2010 (has links)
nÃo hà / Dentre aspectos referentes ao fortalecimento da economia brasileira nos Ãltimos anos, destaca-se a atuaÃÃo de empresas dentro do segmento econÃmico do comÃrcio exterior. A economia do Estado do Cearà nÃo se difere das demais de nosso paÃs quando se estudam aspectos logÃsticos vitais para tal evoluÃÃo do grau de competitividade nos diversos nÃveis. A logÃstica de transporte, mais especificamente a portuÃria, assume um papel diretamente responsÃvel e indispensÃvel pelo desenvolvimento das empresas e indÃstrias instaladas no CearÃ. De forma a objetivar um maior controle aduaneiro e agilidade nos desembaraÃos de cargas tem-se a implementaÃÃo do Siscomex Carga pela Secretaria da Receita Federal do Brasil. Assim esta pesquisa objetiva mensurar, utilizando-se uma natureza qualitativa de pesquisa, os impactos logÃsticos decorrentes da implementaÃÃo do Siscomex Carga como instrumento de validaÃÃo dos processos de desembaraÃo aduaneiro, junto Ãs maiores empresa do Estado do CearÃ. Justificado, dessa forma, pela importÃncia e relevÃncia econÃmica das maiores empresas do Estado do CearÃ, por este trabalho pesquisadas, e a influÃncia delas junto ao volume de cargas movimentadas nos portos de nosso Estado. A metodologia aplicada na pesquisa deste trabalho fundamenta-se essencialmente na busca de informaÃÃes inicialmente bibliogrÃficas, coleta de dados, posteriormente aplicaÃÃo de questionÃrio semi-estruturado e entrevistas abertas, fundamentais para a compreensÃo do tema. A partir dos dados coletados se constituiu uma anÃlise que possibilita uma compreensÃo e caracterizaÃÃo das influÃncias do sistema analisado e a sua importÃncia logÃstica junto Ãs empresas pesquisadas. Verificando-se, portanto, que por parte das empresas entrevistadas tem-se a percepÃÃo clara de que os impactos logÃsticos sÃo melhor visualizados no tempo de desembaraÃo de cargas do que no custo direto de procedimentos alterados com a chegada do novo sistema Siscarga. / Among the aspects related to the strengthening of the Brazilian economy in recent years highlight the performance of companies within the economic sector of foreign trade. The economy of the State of Cearà is not too different from the rest of our country when studying the logistical aspects vital to such a development of the degree of competitiveness at different levels. The logistics of transportation, more specifically the port, plays a role directly responsible and indispensable for the development of businesses and industries in Cearà installed. In order to aim for greater control and agility in customs clearances of cargo has been the implementation of the load Siscomex by Secretaria da Receita Federal do Brasil. So this research aims to measure in a qualitative research impacts logistics of implementing the Siscomex Credit as a tool for validation of customs clearance procedures, along with top company in the state of CearÃ. Justified in this way, the importance and economic relevance of the largest companies in the state of CearÃ, in this work investigated the influence of the same with the volume of cargoes handled in the ports of our state. The methodology applied in this research work is based mainly on the search for bibliographic information initially, data collection, after application of a semi-structured and open interviews, key to understanding the issue. From the collected data was an analysis that allows an understanding and characterization of the influences of the analyzed system and its importance among logistics companies surveyed. There was, therefore, that by the companies interviewed has a clear perception that the logistics impacts are best viewed at the time of clearance of cargo than the direct cost of procedures changed with the arrival of the new system, SISCARGA.
13

On the Scalability of Four Multi-Agent Architectures for Load Control Management in Intelligent Networks / On the Scalability of Four Multi-Agent Architectures for Load Control Management in Intelligent Networks

Ahmad, Raheel January 2003 (has links)
Paralleling the rapid advancement in the network evolution is the need for advanced network traffic management surveillance. The increasing number and variety of services being offered by communication networks has fuelled the demand for optimized load management strategies. The problem of Load Control Management in Intelligent Networks has been studied previously and four Multi-Agent architectures have been proposed. The objective of this thesis is to investigate one of the quality attributes namely, scalability of the four Multi-Agent architectures. The focus of this research would be to resize the network and study the performance of the different architectures in terms of Load Control Management through different scalability attributes. The analysis has been based on experimentation through simulations. It has been revealed through the results that different architectures exhibit different performance behaviors for various scalability attributes at different network sizes. It has been observed that there exists a trade-off in different scalability attributes as the network grows. The factors affecting the network performance at different network settings have been observed. Based on the results from this study it would be easier to design similar networks for optimal performance by controlling the influencing factors and considering the trade-offs involved. / C/o Aijaz Ahmad, House No. E-97/A, Street No. 4, Super Town, Walton Road, Lahore Cantt.-Pakistan, Tel +92-42-6655070
14

Slung Load Control and User Interfaces for a Quadrotor Micro Air Vehicle

Rudner, Mikael, Hansson, Niklas January 2011 (has links)
The use of small scale Unmanned Aerial Vehicles (UAVs) is quickly becomingcommonplace in many domains. Operating such vehicles often requires using aspecialized radio control (RC) transmitter. One objective of this thesis is toinvestigate the use of other means of controlling a particular type of a UAV - aquadrotor. Two types of alternative devices are investigated, a standard gamingconsole controller PlayStation 3 gamepad (PS3 gamepad) and a smartphone(Android OS based). The purpose of substituting the RC controller is to make iteasier for a novice user to operate a UAV. The second objective is to investigate solutions to the problem of slung load control. A slung load is a uniform mass attached to a platform with a wire that may swingfreely. The slung load control problem consists of several subproblems: slung loadmodeling, altitude control, filtering of sensor data and the slung load control itself. The purpose of controlling the slung load is to reduce the oscillations of the load inflight and to minimize its influence on the flight performance of a UAV. Both types of alternative interfaces to the UAV were designed and implemented. Inorder to interface with the quadrotor platform at hand a new communicationprotocol based on TCP/IP was introduced. A study of the design process and typicaluse cases was performed. The two types of interfaces were evaluated by a group oftarget users as well as in real flight tests. The game controller was easy to use whilethe smartphone interface required automatic altitude control to be really useful. The evaluators found that the smartphone provided a smoother control over the steeringcompared to using the joystick on a game controller. The slung load control problem was investigated theoretically and in practice on astationary testing rig. The altitude control problem has been addressed byincorporating a PID controller which uses filtered data from a pressure sensor. ThePID control was extended with an anti-windup mechanism combined with afeedforward control of the tilt angle. A mechanism for a smooth transition from themanual to automatic altitude control modes was implemented and verified in flighttests.
15

Estimation de l'effacement de consommation électrique d'un groupe de clients résidentiels / Residential electricity demand reduction estimation

Hatton, Leslie 09 January 2015 (has links)
Dans cette thèse, nous développons une méthode d’estimation de l’effacement de consommation électrique d’un groupe de clients résidentiels. L’effacement, correspondant à une réduction de la puissance électrique sur une certaine durée, est désormais valorisé sur les marchés électriques et contribue à équilibrer le système électrique. Pour le quantifier, il faut estimer qu’elle aurait été la puissance appelée, i.e. la baseline, en l’absence de l’effacement. Ce dernier s’obtient alors par différence de la baseline et de la puissance réalisée. Les méthodes d’estimation de la baseline reposent sur des profils de consommation, des modèles de régression et des méthodes fondées sur un groupe de contrôle. Ces dernières offrent les résultats les plus précis mais déployer un groupe de contrôle aléatoire pour un usage opérationnel n’est pas envisageable.On s’intéresse donc à sélectionner un groupe de contrôle non-expérimental selon deux approches : la première emploie les caractéristiques observables des clients contrôles et la seconde leurs courbes de charge individuelles. Cette dernière idée consiste à sélectionner ces individus tels que la distance entre leur courbe de charge moyenne et celle du groupe recevant les effacements soit minimale. A cette fin, nous proposons un algorithme de sélection et adaptons les méthodes de régression sous contrainte, ridge et Lasso. Ces nouvelles méthodes procurent les meilleurs résultats. Enfin, pour estimer l’effacement en ligne, nous mettons en place un outil innovant qui associe un système de gestion de flux de données à un logiciel statistique / In this thesis, we develop a method in order to estimate the residential electricity demand reduction. The demand reduction or the curtailment, aiming at reducing the energy use during a short period, is currently enhanced on electricity markets and contributes to balance the electric system. To quantify it, one has to estimate the consumption, i.e. the baseline, which would have been used in the absence of the demand reduction. The curtailment is then obtained by subtracting the metered load during the demand reduction event from the baseline. The baseline estimation methods rely on day or weather matching methods, regression models and control group approaches. These one give the more accurate results but deploying a randomized control group is not possible for an operational use.We are then interested in selecting a non-experimental control group according to two approaches: the first uses the observable characteristics of the control customers and the second their individual load curves. This last idea consists in selecting those individuals such that the distance between their average load curve and that of the demand reduction group is minimal. To this end, we develop a forward selection algorithm and apply the constrained regression methods, ridge and Lasso. These methods provide the best results. Finally, we set up an innovative process which links a data flow module with a statistical software and allows to estimate the demand reduction on-line.
16

Utmaningar för ökad efterfrågeflexibilitet : En studie om hushålls engagemang till efterfrågeflexibilitet och ansvarsfördelningen på den svenska elmarknaden / Challenges for increased demand flexibility : A study of households' commitment to demand flexibility and the division of responsibilities in the Swedish electricity market

Andersson, Martin, Ferm, Carl January 2021 (has links)
Purpose: The purpose of the study is to examine households attitudes and commitment to demand side flexibility as well as the various actors perceptions of the division of responsibilities in the electricity market and the information available to households. Research questions:                   – What are the main factors for private electricity customers to be able to contribute with demand side flexibility to the electricity system? – What challenges and opportunities can be identified with increased demand side flexibility? Method: The study was based on an abductive approach, where the collection of primary data is of a quantitative and qualitative nature. The qualitative part was collected through 9 semi-structured interviews with actors linked to the electricity market. Collection of quantitative data was done through a survey aimed at households with a total of 110 respondents. The results of the data collection have been analyzed thematically together with the theoretical framework. Conclusions: The main factors for increased demand flexibility are, firstly, a clear division of responsibilities between authorities, households and other players in the electricity market. Secondly, well-developed information channels are required that can be made possible through new technology. Finally, an electricity market is required that allows new actors such as an aggregator. The challenges include engaging households, currently low profitability for demand side flexibility and a set of regulations and tariffs that are lagging behind in development. The opportunities are future changes in the electricity price that speak in favor of increased profitability for demand side flexibility and a change to more dynamic and flexible electricity network tariffs.
17

Contrôle de charge des réseaux IoT : d'une étude théorique à une implantation réelle / IoT networks load control mechanisms : From a theoretical study to a real implementation

Chelle, Hugo 18 December 2018 (has links)
Prenons en exemple une salle de classe composée d’un professeur et de nombreux élèves, lorsque trop d’élèves s’adressent en même temps au professeur ce dernier n’est plus en mesure de comprendre les paroles transmisses par les élèves. Cette illustration s’étend évidemment aux systèmes de communications sans fil (la 4G par exemple). Dans ces systèmes, les terminaux (les élèves par analogie) transmettent sur un canal, nommé canal en accès aléatoire, des messages qui sont potentiellement réceptionnés par la station de base (le professeur par analogie). Ces canaux ne sont habituellement pas surchargés car leur capacité (nombre de messages reçus par seconde) est tellement importante qu’il est très complexe de surcharger le canal. L’émergence de l’Internet des objets où des milliards de petits objets devraient être déployés partout dans le monde a changé la donne. Étant donné leur nombre et leur type de trafic, ces derniers peuvent surcharger les canaux en accès aléatoire. Ainsi, le sujet : « contrôle de charge des canaux en accès aléatoire » a connu un gain d’intérêts ces dernières années. Dans cette thèse nous avons développé des algorithmes de contrôle de charge permettant d’éviter qu’une station de base soit surchargée. Cela est très utile pour les opérateurs Télécoms, ils sont désormais certains qu’il y n’y aura pas de perte de service à cause de ces surcharges. Tous les principes développés dans cette thèse seront intégrés dans un futur proche aux produits IoT d’Airbus. / Take for example a classroom composed of a teacher and many students. When too many students address at the same time to the teacher, the latter is no longer able to understand the words transmitted by students. This illustration obviously extends to wireless communication systems (the 4G for example). In these systems, terminals (students by analogy) transmit on a channel, named random access channel, messages that are potentially received by the base station (the teacher by analogy). These channels are usually not overloaded because their capacity (number of messages received per second) is so important that it is very complex to overload the channel. The emergence of the Internet of Things, where billions of small objects should be deployed around the world, has changed the game. Due to their number and type of traffic, they can overload random access channels. Therefore, the subject: "load control of random access channels" has seen an increase in interest in recent years. In this PhD we have developed load control algorithms to prevent a base station from being overloaded. This is very useful for telecom operators, they are now certain that there will be no loss of service because of these overloads. All the principles developed in this thesis will be integrated in the near future within Airbus IoT products
18

Design and Implementation of a Web-based Home Energy Management System for Demand Response Applications

Rahman, Md Moshiur 06 August 2013 (has links)
The objective of this work is to design and implement an architectural framework for a web-based demand management system that allows an electric utility to reduce system peak load by automatically managing end-use appliances based on homeowners' preferences. The proposed framework comprises the following components: human user interface, home energy management (HEM) algorithms, web services for demand response communications, selected ZigBee and smart energy profile features for appliance interface, and security aspects for a web-based HEM system. The proposed web-based HEM system allows homeowners to be more aware about their electricity consumption by allowing visualization of their real-time and historical electricity consumption data. The HEM system enables customers to monitor and control their household appliances from anywhere with an Internet connection. It offers a user-friendly and attractive display panel for a homeowner to easily set his/her preferences and comfort settings. An algorithm to autonomously control appliance operation is incorporated in the proposed web-based HEM system, which makes it possible for residential customers to participate in demand response programs. In this work, the algorithm is demonstrated to manage power-intensive appliances in a single home, keeping the total household load within a certain limit while satisfying preset comfort settings and user preferences. Furthermore, an extended version of the algorithm is demonstrated to manage power-intensive appliances for multiple homes within a neighborhood. As one of the demand response (DR)-enabling technologies, the web services-based DR communication has been developed to enable households without smart meters or advanced metering infrastructure (AMI) to participate in a DR event via the HEM system. This implies that an electric utility can send a DR signal via a web services-enabled HEM system, and appropriate appliances can be controlled within each home based on homeowner preferences. The interoperability with other systems, such as utility systems, third-party Home Area Network (HAN) systems, etc., is also taken into account in the design of the proposed web services-based HEM system. That is, it is designed to allow interaction with authorized third-party systems by means of web services, which are collectively an interface for machine-to-machine interaction. This work also designs and implements device organization and interface for end-use appliances utilizing ZigBee Device Profile and Smart Energy Profile. Development of the Home Area Network (HAN) of appliances and the HAN Coordinator has been performed using a ZigBee network. Analyses of security risks for a web-based HEM system and their mitigation strategies have been discussed as well. / Master of Science
19

Reinforcement Learning for Wind Turbine Load Control: How AI can drive tomorrow‘s wind turbines

Westerbeck, Nico, Gonsior, Julius, Marten, David, Perez-Becker, Sebastian 30 May 2023 (has links)
Load control strategies for wind turbines are used to reduce the structural wear of the turbine without reducing energy yield. Until now, these control strategies are almost exclusively built up-on linear approaches like PID and model-based controllers due to their robustness. However, advances in turbine size and capabilities create a need for more complex control strategies that can effectively address design challenges in modern turbines. This work presents WINDL, a load control policy based on a neural network, which is trained through model-free Reinforcement Learning (RL) on a simulated wind turbine. While RL has achieved great success in the past on games and simple simulation benchmarks, applications to more complex control problems are starting to emerge just recently. We show that through the usage of regularization techniques and signal transformations, such an application to the field of wind turbine load control is possible. Using a smoothness regularizer, we incentivize the highly non-linear neural network policy to output control actions that are safe to apply to a wind turbine. The Coleman transformation, a common tool for the design of traditional PID-based load control strategies, is used to project signals into a stationary coordinate space, increasing robustness and final policy performance. Trained to control a large offshore turbine in a model-free fashion, WINDL finds a control policy that outperforms a state-of-the-art controller based on the IPC strategy with respect to the prima-ry optimization goal blade loads. Using the DEL metric, we measure 54.1% lower blade loads in the steady wind and 13.45% lower blade loads in the turbulent wind scenario. While such levels of blade reduction come with slightly worse performance on secondary optimi-zation goals like pitch wear and power production, we demonstrate the ability to control the trade-off between different optimization goals on the example of pitch versus blade loads. To comple-ment our findings, we perform a qualitative analysis of the policy behavior and learning process. We believe our work to be the first application of RL to wind turbine load control that exceeds baseline performance in the primary optimization metric, opening up the possibility of including specialized load controllers for targeting critical design driving scenarios of modern large wind turbines.:Problem Method Aim Results Conclusion
20

Examining Direct Load Control Within Demand Response Programs

Bonina Zimath, Maria 01 January 2023 (has links) (PDF)
The power system is a complex entity with unique plant designs, control systems, and market strategies. For many years, engineers have developed advanced technology to keep the grid efficient and balanced. With the rise of renewable sources, some new technology and programs must be developed to keep the quality of the power system. Unlike traditional power plants, renewable energy is highly dependent on environmental factors, such as sunlight and wind, meaning the generation depends on an unpredictable source of fuel. As the grid moves to more sustainable sources, the power market faces a growing challenge of less control over the forecasted supply offered by each renewable plant. This uncertainty creates a high need to develop alternative methods to ensure the power supply always meets demand. With diminishing control over our generation, one potential solution has been to explore demand response initiatives. Demand response focuses on the engagement of consumers to reduce the electricity demand, facilitating sub-hourly efforts on the supply side. This paper will analyze the effect of demand response efforts on the participants and provide insights into potential benefits and challenges associated with implementing demand response strategies. The findings of the studies will contribute to a better understanding on the compensation structure of current Direct Load Control programs and the level of participation required for it to be effectively integrated into the power system, promoting a more reliable and sustainable future.

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