264 research outputs found

    Advances and Technologies in High Voltage Power Systems Operation, Control, Protection and Security

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    The electrical demands in several countries around the world are increasing due to the huge energy requirements of prosperous economies and the human activities of modern life. In order to economically transfer electrical powers from the generation side to the demand side, these powers need to be transferred at high-voltage levels through suitable transmission systems and power substations. To this end, high-voltage transmission systems and power substations are in demand. Actually, they are at the heart of interconnected power systems, in which any faults might lead to unsuitable consequences, abnormal operation situations, security issues, and even power cuts and blackouts. In order to cope with the ever-increasing operation and control complexity and security in interconnected high-voltage power systems, new architectures, concepts, algorithms, and procedures are essential. This book aims to encourage researchers to address the technical issues and research gaps in high-voltage transmission systems and power substations in modern energy systems

    Multi-Agent Systems

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    A multi-agent system (MAS) is a system composed of multiple interacting intelligent agents. Multi-agent systems can be used to solve problems which are difficult or impossible for an individual agent or monolithic system to solve. Agent systems are open and extensible systems that allow for the deployment of autonomous and proactive software components. Multi-agent systems have been brought up and used in several application domains

    Dynamic Core Community Detection and Information Diffusion Processes on Networks

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    Interest in network science has been increasingly shared among various research communities due to its broad range of applications. Many real world systems can be abstracted as networks, a group of nodes connected by pairwise edges, and examples include friendship networks, metabolic networks, and world wide web among others. Two of the main research areas in network science that have received a lot of focus are community detection and information diffusion. As for community detection, many well developed algorithms are available for such purposes in static networks, for example, spectral partitioning and modularity function based optimization algorithms. As real world data becomes richer, community detection in temporal networks becomes more and more desirable and algorithms such as tensor decomposition and generalized modularity function optimization are developed. One scenario not well investigated is when the core community structure persists over long periods of time with possible noisy perturbations and changes only over periods of small time intervals. The contribution of this thesis in this area is to propose a new algorithm based on low rank component recovery of adjacency matrices so as to identify the phase transition time points and improve the accuracy of core community structure recovery. As for information diffusion, traditionally it was studied using either threshold models or independent interaction models as an epidemic process. But information diffusion mechanism is different from epidemic process such as disease transmission because of the reluctance to tell stale news and to address this issue other models such as DK model was proposed taking into consideration of the reluctance of spreaders to diffuse the information as time goes by. However, this does not capture some cases such as the losing interest of information receivers as in viral marketing. The contribution of this thesis in this area is we proposed two new models coined susceptible-informed-immunized (SIM) model and exponentially time decaying susceptible-informed (SIT) model to successfully capture the intrinsic time value of information from both the spreader and receiver points of view. Rigorous analysis of the dynamics of the two models were performed based mainly on mean field theory. The third contribution of this thesis is on the information diffusion optimization. Controlling information diffusion has been widely studied because of its important applications in areas such as social census, disease control and marketing. Traditionally the problem is formulated as identifying the set of k seed nodes, informed initially, so as to maximize the diffusion size. Heuristic algorithms have been developed to find approximate solutions for this NP-hard problem, and measures such as k-shell, node degree and centrality have been used to facilitate the searching for optimal solutions. The contribution of this thesis in this field is to design a more realistic objective function and apply binary particle swarm optimization algorithm for this combinatorial optimization problem. Instead of fixating the seed nodes size and maximize the diffusion size, we maximize the profit defined as the revenue, which is simply the diffusion size, minus the cost of setting those seed nodes, which is designed as a function of degrees of the seed nodes or a measure that is similar to the centrality of nodes. Because of the powerful algorithm, we were able to study complex scenarios such as information diffusion optimization on multilayer networks.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145937/1/wbao_1.pd
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