An MDP decomposition approach for traffic control at isolated signalized intersections

This article presents a novel approach for the dynamic control of a signalized intersection. At the intersection, there is a number of arrival flows of cars, each having a single queue (lane). The set of all flows is partitioned into disjoint combinations of nonconflicting flows that will receive green together. The dynamic control of the traffic lights is based on the numbers of cars waiting in the queues. The problem concerning when to switch (and which combination to serve next) is modeled as a Markovian decision process in discrete time. For large intersections (i.e., intersections with a large number of flows), the number of states becomes tremendously large, prohibiting straightforward optimization using value iteration or policy iteration. Starting from an optimal (or nearly optimal) fixed-cycle strategy, a one-step policy improvement is proposed that is easy to compute and is shown to give a close to optimal strategy for the dynamic proble

Transient handover blocking probabilities in road covering cellular mobile networks

This paper investigates handover and fresh call blocking probabilities for subscribers moving along a road in a traffic jam passing through consecutive cells of a wireless network. It is observed and theoretically motivated that the handover blocking probabilities show a sharp peak in the initial part of a traffic jam roughly at the moment when the traffic jam starts covering a new cell. The theoretical motivation relates handover blocking probabilities to blocking probabilities in the M/D/C/C queue with time-varying arrival rates. We provide a numerically efficient recursion for these blocking probabilities. \u

Mixing in T-junctions

The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction variable for the average mass fraction and the variance of the mixture fraction for the temporal fluctuations. The results obtained by numerical simulations are verified in a well-defined experiment. The velocity as well as the concentration field are measured in several types of T-junctions. Comparison of the predicted and measured average concentration fields show good agreement if the Schmidt number for turbulent diffusion is taken as 0.2. Temporal concentration fluctuations are calculated and found to be of equal magnitude as spatial fluctuations. Good mixing is obtained in a T-junction if the branch inlet flow is designed to penetrate to the opposite tube wall in the mixer

Desk study of the possible impact of fisheries and other human activities on the marine environment in Mauritania. An exploration

Wageningen IMARES has been contracted by Dutch Ministry of Agriculture, Nature and Food Quality with funding from the “BO PPP”-programme to make an inventory of existing and expected future human activities in that part of the Eastern Atlantic Ocean that forms the Economic Exclusive zone of Mauritania with respect to their possible impact on the marine ecosystem. The inventory will mainly be focused on the different fisheries in the area, but will not be restricted to these. Based on this inventory of activities this report will consider data needed to properly assess the impacts on the ecosystem arising from these and the studies required to gather that data

Microscope and spectacle : on the complexities of using new visual technologies to communicate about wildlife conservation

Acknowledgments We thank our interviewees for granting us access to data and permission to use images; dot.rural Digital Economy Hub, the University of Aberdeen, and the James Hutton Institute for funding and support; Gina Maffey, Tony James, Katrina Myrvang Brown, and two anonymous reviewers for their comments on earlier versions of the manuscript; and JP Vargheese for technical assistance.Peer reviewedPublisher PD

New Technological Interventions in Conservation Conflicts : Countering Emotions and Contested Knowledge

RCUK Digital Economy programme Grant number EP/G066051/1 Open access via Springer Compact AgreementPeer reviewedPublisher PD

The content and context of organizational ethics

The aim of this paper is to provide an empirical contextual picture of what is truly valued most in different public and private sector organizations. Through a series of qualitative in-depth interviews (n = 38), that were a follow-up to an earlier survey study among public and private sector managers (n = 382), a number of crucial organizational values were presented to and discussed with a selection of top managers from a variety of Dutch public and private sector organizations. The decision-making context from the interviews provides insight into why, when, how and to what extent specific values are important. A number of unexpected differences and similarities between organizations with a different sectoral status emerge from the data, which shed new light on existing predispositions on value preferences in government and business conduct. © 2010 The Author. Public Administration © 2010 Blackwell Publishing Ltd

Value Solidity : Differences, Similarities and Conflicts between the Organizational Values of Government and Business

Huberts, L.W.J.C. [Promotor]Graaf, G. de [Copromotor

The injured peritoneum: Consequences of surgery on an organ

__Abstract__ Surgical trauma to the peritoneum is inevitable during abdominal surgery, whether performed by laparoscopy or laparotomy. Obviously, entering the abdominal cavity is an essential prerequisite in order to be able to perform any kind of surgical intervention intra-abdominally. However, among surgeons there is only little awareness of the consequences of this essential part of an abdominal procedure. Postoperative adhesions, responsible for an increased risk of small bowel obstruction, infertility, chronic abdominal pain and considerable difficulties at re-operations, are often taken for granted whereas attempts to prevent them are not being considered. In case of oncological abdominal surgery the traumatised peritoneum may facilitate outgrowth of spilled tumour cells, inducing peritoneal carcinomatosis and hence a worsened outcome for the patient. Increasing the awareness of sequelae of surgical trauma to the peritoneum hopefully leads to a reduction ofthe amount of peritoneal damage during surgery and a decrease in postoperative morbidity for the patient