Introduction

This is the webpage for the seminar of the Intelligent Systems (IS) research group at CWI. For information or questions, please contact the seminar organizer Peter Bosman.

Upcoming Events

Date/Time/Location: April 8, 2013 / 15:30 / M390
Speaker: Hado van Hasselt (Intelligent Systems Group, CWI)
Title: Stacking Under Uncertainty: We Know How To Predict, But How Should We Act?
Abstract: We consider the problem of stacking containers in a given set of stacks of fixed maximum capacity when the pick-up times are stochastic with unknown probability distributions. The goal is to minimize the expected number of times a container is picked up while it is not at the top of its stack. We formulate several algorithms under varying assumptions about the available knowledge about the pick-up-time distributions. We distinguish four qualitatively different settings: 1) we know nothing about the actual distributions, 2) we have point estimates of the means, 3) we have point estimates of means and variances, or 4) we have historical samples of actual pick-up times. For each assumption we propose one or more algorithms. We test the algorithms empirically in many different scenarios, considering both sequential and concurrent arrivals. Additionally, we consider the computational complexity and ease of use of each algorithm.

Date/Time/Location: April 8, 2013 / 15:00 / M390
Speaker: Nicolas Höning (Intelligent Systems Group, CWI)
Title: Fast and revenue-oriented protection of radial LV cables with smart battery operation
Abstract: Low-voltage radial electricity cables will have more and more difficulties to carry the increasing load of novel consumption devices (e.g. electric vehicles) and the expected generated input of decentrally-generated power (e.g. from photovoltaic cells). One solution to avoid replacement is to install a battery at the end of a cable which is expected to be overloaded frequently. The intelligent operation of this battery needs to combine the protection of the cable with optimizing its revenue, in order to be economically viable. This paper formulates the offline optimization problem and proposes two robust heuristic online strategies. We show in computer simulations that these heuristics, which make fast just-in-time responses, reliably deliver good results. Our second heuristic reaches up to 83% of the approximated theoretical optimum.

Date/Time/Location: November 22, 2012 / 15:00 / L016
Speaker: Valentin Robu (Agents, Intelligence, Multimedia Research Group, University of Southampton)
Title: Online Mechanism Design for Dynamic Electric Vehicle Charging
Abstract: Plug-in hybrid electric vehicles are expected to place a considerable strain on local electricity distribution networks, requiring charging to be coordinated in order to accommodate capacity constraints. We design a novel online auction protocol for this problem, wherein vehicle owners use agents to bid for power and also state time windows in which a vehicle is available for charging. This is a multi-dimensional mechanism design domain, with owners having non-increasing marginal valuations for each subsequent unit of electricity. In our design, we couple a greedy allocation algorithm with the occasional cancellation of allocated power, in order to achieve monotonicity and thus truthfulness. We consider two variations: burning at each time step or on-departure. Both mechanisms are evaluated in depth, using data from a real-world trial of electric vehicles in the UK to simulate system dynamics and valuations. The mechanisms provide higher allocative efficiency than a fixed price system, are almost competitive with a standard scheduling heuristic which assumes non-strategic agents, and can sustain a substantially larger number of vehicles at the same per-owner fuel cost saving than a simple random scheme.

Past Events