Optimal Distributed Power Generation Under Network-Load Constraints

In electrical power networks nowadays more and more customers are becoming power-producers, mainly because of the development of novel components for decentralized power generation (solar panels, small wind turbines and heat pumps). This gives rise to the question how many units of each type (solar panel, small wind turbine or central heating power units) can be inserted into any transmission line in the network, such that under given distributions on the typical production and consumption over time, the maximum loads on the lines and components will not be exceeded. In this paper, we present a linear programming model for maximizing the amount of decentralized power generation while respecting the load limitations of the network. We describe a prototype showing that for an example network the maximization problem can be solved efficiently. We also modeled the case were the power consumption and decentralized power generation are considered as stochastic variables, which is inherently more complex

Routing for analog chip designs at NXP Semiconductors

During the study week 2011 we worked on the question of how to automate certain aspects of the design of analog chips. Here we focused on the task of connecting different blocks with electrical wiring, which is particularly tedious to do by hand. For digital chips there is a wealth of research available for this, as in this situation the amount of blocks makes it hopeless to do the design by hand. Hence, we set our task to finding solutions that are based on the previous research, as well as being tailored to the specific setting given by NXP. This resulted in an heuristic approach, which we presented at the end of the week in the form of a protoype tool. In this report we give a detailed account of the ideas we used, and describe possibilities to extend the approach

A Class of Simple Distribution-free Rank-based Unit Root Tests (Revision of DP 2010-72)

We propose a class of distribution-free rank-based tests for the null hypothesis of a unit root. This class is indexed by the choice of a reference density g, which needs not coincide with the unknown actual innovation density f. The validity of these tests, in terms of exact finite sample size, is guaranteed, irrespective of the actual underlying density, by distribution-freeness. Those tests are locally and asymptotically optimal under a particular asymptotic scheme, for which we provide a complete analysis of asymptotic relative efficiencies. Rather than asymptotic optimality, however, we emphasize finitesample performances. Finite-sample performances of unit root tests, however, depend quite heavily on initial values. We therefore investigate those performances as a function of initial values. It appears that our rank-based tests significantly outperform the traditional Dickey-Fuller tests, as well as the more recent procedures proposed by Elliot, Rothenberg, and Stock (1996), Ng and Perron (2001), and Elliott and M¨uller (2006), for a broad range of initial values and for heavy-tailed innovation densities. As such, they provide a useful complement to existing techniques.Unit root;Dickey-Fuller test;Local Asymptotic Normality;Rank test

The asymptotic structure of nearly unstable non-negative integer-valued AR(1) models

This paper considers non-negative integer-valued autoregressive processes where the autoregression parameter is close to unity. We consider the asymptotics of this `near unit root' situation. The local asymptotic structure of the likelihood ratios of the model is obtained, showing that the limit experiment is Poissonian. To illustrate the statistical consequences we discuss efficient estimation of the autoregression parameter and efficient testing for a unit root.Comment: Published in at http://dx.doi.org/10.3150/08-BEJ153 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

A systematic review of changes in women’s physical activity before and during pregnancy and the postnatal period

Objectives: To determine the magnitude and type of naturally occuring physical activity changes in women around the time of pregnancy. Background: This systematic review synthesises the results of studies examining naturally occurring physical activity in women before they become pregnant and the magnitude and type of changes during pregnancy and the postnatal period. Methods: Electronic databases were searched for relevant articles and PRISMA guidelines for selection of articles were used. Only studies examining naturally occurring, non-intervention changes in regular activity levels were included. The quality assessment was based on protocols of the Cochrane Database of Systematic Reviews. Of the initial 720 titles, 24 studies met the inclusion criteria and were included in the final review. Results: Compared to pre-pregnancy, the magnitude of physical activity decreased over the course of pregnancy and postnatally and the types of activities tended to be of lesser intensity than pre-pregnancy. The quality of the research was varied; methodological limitations included using subjective methods of assessment of physical activity (9/24), failing to report reliabilities or validity of measures used (8/24), no information on parity (13/24) or level of fitness prior to pregnancy (11/24). Conclusion: The evidence suggests a marked decrease in the amount and type of moderate to strenuous physical activity during the transition to motherhood, which does not always increase again postpartum. Patient education targeting specific physical activities at regular intervals during and after pregnancy to improve long-term maternal health is necessary

Simulation of emotions of agents in virtual environments using neural networks

A distributed architecture for a system simulating the emotional state of an agent acting in a virtual environment is presented. The system is an implementation of an event appraisal model of emotional behaviour and uses neural networks to learn how the emotional state should be influenced by the occurrence of environmental and internal\ud stimuli. A part of the modular system is domain-independent. The system can easily be adapted for handling different events that influence the emotional state. A first\ud prototype and a testbed for this architecture are presented

An Action Selection Architecture for an Emotional Agent

An architecture for action selection is presented linking emotion, cognition and behavior. It defines the information and emotion processes of an agent. The architecture has been implemented and used in a prototype environment