Large-scale coalition formation: application in power distribution systems

Doctor of PhilosophyDepartment of Computing and Information SciencesScott A. DeLoachCoalition formation is a key cooperative behavior of a system of multiple autonomous agents. When the capabilities of individual agents are not su fficient for the improvement of well-being of the individual agents or of the entire system, the agents can bene t by joining forces together in coalitions. Coalition formation is a technique for finding coalitions that are best fi tted to achieve individual or group goals. This is a computationally expensive task because often all combinations of agents have to be considered in order to find the best assignments of agents to coalitions. Previous research has therefore focused mainly on small-scale or otherwise restricted systems. In this thesis we study coalition formation in large-scale multi-agent systems. We propose an approach for coalition formation based on multi-agent simulation. This approach allows us to find coalitions in systems with thousands of agents. It also lets us modify behaviors of individual agents in order to better match a specific coalition formation application. Finally, our approach can consider both social welfare of the multi-agent system and well-being of individual self-interested agents. Power distribution systems are used to deliver electric energy from the transmission system to households. Because of the increased availability of distributed generation using renewable resources, push towards higher use of renewable energy, and increasing use of electric vehicles, the power distribution systems are undergoing significant changes towards active consumers who participate in both supply and demand sides of the electricity market and the underlying power grid. In this thesis we address the ongoing change in power distribution systems by studying how the use of renewable energy can be increased with the help of coalition formation. We propose an approach that lets renewable generators, which face uncertainty in generation prediction, to form coalitions with energy stores, which on the other hand are always able to deliver the committed power. These coalitions help decrease the uncertainty of the power generation of renewable generators, consequently allowing the generators to increase their use of renewable energy while at the same time increasing their pro fits. Energy stores also bene t from participating in coalitions with renewable generators, because they receive payments from the generators for the availability of their power at specific time slots. We first study this problem assuming no physical constraints of the underlying power grid. Then we analyze how coalition formation of renewable generators and energy stores in a power grid with physical constraints impacts the state of the grid, and we propose agent behavior that leads to increase in use of renewable energy as well as maintains stability of the grid

GLOBALIZATION AS A RISK FACTOR FOR CREATIVITY AND INNOVATIVENESS

The innovation pressure for the German economy increases with globalization. Yet, is this also reflected in an increased innovation activity and creativity? The article at hand presents an opposing perspective: based on some statistical analyses that indeed show a decline of innovation in Germany and other developed countries during the past years, several lines of argument are presented to explain that development. Risks arising from globalization for the creativity and innovation potential of companies are identified in economic, business and psychological areas, and their possible impact on creativity and innovation is explained in detail. Furthermore, possible countermeasures are summarized

981-52 Six-minute Walk Compared to Peak and Low-level Aerobic Capacity in 302 Patients with Heart Failure

Distances walked spontaneously during 6 min may reflect peak exerc capacity, the ability to sustain 6 min of low exercise without anaerobic metabolism, and non-metabolic factors such as stride. To determine how well 6-min walks in 302 heart failure patients reflected aerobic capacity at peak exercise (pkVO2) and/or R (VCO2/VO2) after 6min of low-level exercise similar to walking, 6-min walks were measured within 48 hrs of bicycle exercise with gas exchange during 6min 20-watt riding and then during incremental exercise.Although 6 min walk correlated with extremes of pkVO2, it varied widely (r=0.25) when pkVO2 was 10–20ml/kg/min (generally Class II-III). Although 6 min 20W ride required VO2 9 ±2ml/kg/min, similar to 3 METS estimated for walking, 6-min 20W R did not correlate well inversely with 6 min walk distance except at very short and long walks.In moderate heart failure, 6 min walk reflects factors other than aerobic capacity at peak or during 6 min of sustained low-level exercise

The totally asymmetric exclusion process on a ring: Exact relaxation dynamics and associated model of clustering transition

The totally asymmetric simple exclusion process in discrete time is considered on finite rings with fixed number of particles. A translation-invariant version of the backward-ordered sequential update is defined for periodic boundary conditions. We prove that the so defined update leads to a stationary state in which all possible particle configurations have equal probabilities. Using the exact analytical expression for the propagator, we find the generating function for the conditional probabilities, average velocity and diffusion constant at all stages of evolution. An exact and explicit expression for the stationary velocity of TASEP on rings of arbitrary size and particle filling is derived. The evolution of small systems towards a steady state is clearly demonstrated. Considering the generating function as a partition function of a thermodynamic system, we study its zeros in planes of complex fugacities. At long enough times, the patterns of zeroes for rings with increasing size provide evidence for a transition of the associated two-dimensional lattice paths model into a clustered phase at low fugacities.Comment: 9 pages 5 figures accepted for publication in Physica

Ueber Substitutions-producte des Paraazotoluols

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