118 research outputs found

    The Use of Marginal Energy Costs in the Design of U.S. Capacity Markets

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    This paper surveys the development of marginal cost theories used in the optimal allocation of scarce resources, and examines the application of these theories to current-day electricity capacity markets. The different approaches in use today to ensure grid reliability and incentivize new resources are examined. Market challenges are surveyed, as well as empirical findings that suggest that current market approaches do not provide proper incentives. We conclude that the so-called missing money is not missing because of defects in market designs, or so-called administrative actions---money to incentivize investments is missing due to a misapplication of marginal cost theory

    Markov Chain Monte Carlo Method without Detailed Balance

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    We present a specific algorithm that generally satisfies the balance condition without imposing the detailed balance in the Markov chain Monte Carlo. In our algorithm, the average rejection rate is minimized, and even reduced to zero in many relevant cases. The absence of the detailed balance also introduces a net stochastic flow in a configuration space, which further boosts up the convergence. We demonstrate that the autocorrelation time of the Potts model becomes more than 6 times shorter than that by the conventional Metropolis algorithm. Based on the same concept, a bounce-free worm algorithm for generic quantum spin models is formulated as well.Comment: 5 pages, 5 figure

    Stationarity and Geometric Ergodicity of BEKK Multivariate GARCH Models

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    Conditions for the existence of strictly stationary multivariate GARCH processes in the so-called BEKK parametrisation, which is the most general form of multivariate GARCH processes typically used in applications, and for their geometric ergodicity are obtained. The conditions are that the driving noise is absolutely continuous with respect to the Lebesgue measure and zero is in the interior of its support and that a certain matrix built from the GARCH coefficients has spectral radius smaller than one. To establish the results semi-polynomial Markov chains are defined and analysed using algebraic geometry.Comment: version to appear in Stochastic Processes and their Applications, 2011; http://www.sciencedirect.com/science/article/pii/S030441491100137

    On the flow-level stability of data networks without congestion control: the case of linear networks and upstream trees

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    In this paper, flow models of networks without congestion control are considered. Users generate data transfers according to some Poisson processes and transmit corresponding packet at a fixed rate equal to their access rate until the entire document is received at the destination; some erasure codes are used to make the transmission robust to packet losses. We study the stability of the stochastic process representing the number of active flows in two particular cases: linear networks and upstream trees. For the case of linear networks, we notably use fluid limits and an interesting phenomenon of "time scale separation" occurs. Bounds on the stability region of linear networks are given. For the case of upstream trees, underlying monotonic properties are used. Finally, the asymptotic stability of those processes is analyzed when the access rate of the users decreases to 0. An appropriate scaling is introduced and used to prove that the stability region of those networks is asymptotically maximized

    Sparse and Constrained Stochastic Predictive Control for Networked Systems

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    This article presents a novel class of control policies for networked control of Lyapunov-stable linear systems with bounded inputs. The control channel is assumed to have i.i.d. Bernoulli packet dropouts and the system is assumed to be affected by additive stochastic noise. Our proposed class of policies is affine in the past dropouts and saturated values of the past disturbances. We further consider a regularization term in a quadratic performance index to promote sparsity in control. We demonstrate how to augment the underlying optimization problem with a constant negative drift constraint to ensure mean-square boundedness of the closed-loop states, yielding a convex quadratic program to be solved periodically online. The states of the closed-loop plant under the receding horizon implementation of the proposed class of policies are mean square bounded for any positive bound on the control and any non-zero probability of successful transmission

    Veröffentlichungen aus dem Staatsarchiv der Freien und Hansestadt Hamburg

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    Das Staatsarchiv Hamburg feierte 2010 sein 300-jÀhriges Bestehen. Sein VorlÀufer wurde bereits im Jahre 1293 erstmals erwÀhnt und somit die Aufbewahrung wichtiger Dokumente der Stadt an zentraler Stelle bezeugt. Doch erst seit dem 11. September 1710, dem Amtsantritt von Nicolaus Stampeel als wissenschaftlicher Archivar bei der Stadt Hamburg, werden Dokumente systematisch ausgewÀhlt, bewahrt und erschlossen. Dieses JubilÀum hat das Staatsarchiv mit einem breit gefÀcherten Veranstaltungsprogramm begangen, zu dem auch VortrÀge und Lesungen gehörten, die in der hier vorliegenden Festschrift abgedruckt sind.In 2010, the Hamburg State Archives celebrated its 300th anniversary. The Archives\u27 forerunner was first mentioned in 1293 and thus testified to the preservation of important documents of the city in a central place. But it was not until September 11th, 1710, when Nicolaus Stampeel took office as a scientific archivist at the City of Hamburg. From then on, documents were systematically selected, preserved and indexed. This anniversary was celebrated by the State Archives with a broad programme of events, which included lectures and readings printed in the commemorative volume available here
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