Heuristics and metaheuristics for heavily constrained hybrid flowshop problems

Due to the current trends in business as the necessity to have a large catalogue of products, orders that increase in frequency but not in size, globalisation and a market that is increasingly competitive, the production sector faces an ever harder economical environment. All this raises the need for production scheduling with maximum efficiency and effectiveness. The first scientific publications on production scheduling appeared more than half a century ago. However, many authors have recognised a gap between the literature and the industrial problems. Most of the research concentrates on optimisation problems that are actually a very simplified version of reality. This allows for the use of sophisticated approaches and guarantees in many cases that optimal solutions are obtained. Yet, the exclusion of real-world restrictions harms the applicability of those methods. What the industry needs are systems for optimised production scheduling that adjust exactly to the conditions in the production plant and that generates good solutions in very little time. This is exactly the objective in this thesis, that is, to treat more realistic scheduling problems and to help closing the gap between the literature and practice. The considered scheduling problem is called the hybrid flowshop problem, which consists in a set of jobs that flow through a number of production stages. At each of the stages, one of the machines that belong to the stage is visited. A series of restriction is considered that include the possibility to skip stages, non-eligible machines, precedence constraints, positive and negative time lags and sequence dependent setup times. In the literature, such a large number of restrictions has not been considered simultaneously before. Briefly, in this thesis a very realistic production scheduling problem is studied. Various optimisation methods are presented for the described scheduling problem. A mixed integer programming model is proposed, in order to obtaiUrlings ., T. (2010). Heuristics and metaheuristics for heavily constrained hybrid flowshop problems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8439Palanci

Developing a Tool for Selection for Medical School : A search for academic and non-academic parameters to predict future medical school performance

Worldwide places in medical school are scarce and medical education and training are expensive for providers and learners. Therefore, medical schools aim to offer the places available only to those applicants with the highest probability of successful medical training and subsequent career. To reach this goal, medical schools have developed several selection procedures, including interviews, admission tests and other measures of personal competencies. Uniquely in the Netherlands, selection was organised nationally based on a lottery that is weighted for academic attainment. However, both the lottery and the unproven selection procedures have been described as unfair to medical school applicants, as neither includes any truly objective criteria for predicting future performance. The Dutch situation in which access to medical school was granted by lottery and the possibility to select up to 50% of the students by a selection procedure provided a unique opportunity to form a control group of randomly admitted students to compare with those selected. We developed an evidence-based selection procedure addressing non-academic (i.e. motivation) as well as academic skills. The former evaluated motivation through the determination of the candidate’s active involvement in extracurricular activities, the latter by tests concerning the study skills of candidates in a medical school context. The main outcome was that the relative risk for dropping out of medical school was significantly lower in selected students than in controls admitted by lottery. Those selected obtained a higher mean grade than the lottery admitted students on their clerkships. Thereby selected students participated more often in extracurricular activities, which was also associated with higher clerkship grades

The Young Child’s Cognition:Intervention and innovative measurement

Understanding and stimulating the cognitive skills of very young children is very important. In order to do this, it is common practice to use standardised tests. In this thesis, it is investigated whether valuable information can also be collected in a playful way through the use of technological developments. In an initial study in this thesis, the effectivity of a cognitive intervention is examined, in this case preschool education. A positive connection is found between preschool education and test results at school. The rest of the thesis researches innovative ways to measure specific cognitive skills, namely the executive functions, in preschool-age children. An existing programmable robot, the Bee-Bot, was used and a ‘serious game’ was developed: Clever Maze. Clever Maze looks like a wooden maze, but it can collect information about how the preschoolers solve mazes and how they play with them. Funded by Maastricht University: Human Enhancement and Learning (HEaL

Spectral Analysis of Correlated One-Dimensional Systems with Impurities

An averaging procedure is proposed to account for spectral features of correlated one-dimensional systems in the presence of non-magnetic impurities. The dynamical spin structure factor for a corresponding random ensemble of Heisenberg chain segments is calculated by exact numerical diagonalization. It is shown that a few-pole approximation is sufficient to describe the numerical results. A similar analysis is proposed for the discussion of experimental spectra, such as obtained by inelastic neutron scattering measurements on Zn-doped CuO chains. By examination of the disorder-induced pseudo-gap, the loss of spectral weight, and the discrete peak structures due to smallest-cluster contributions, the underlying impurity distribution function can be determined.Comment: RevTex, 4 pages with 4 eps figure

A framework for the design and analysis of incentive systems for food safety control in supply chains

Since 2005 the EU food industry has primary legal responsibility for food safety control. This requires new responsibilities and relationships between government and industry, and between companies. This research presents a framework for incentive systems for food safety control in supply chains. It emphasizes key elements of food safety control from multiple perspectives and provides insights for the design and analysis of incentive systems for food safety control. An incentive system combines inter-company incentive mechanisms with intra-company decision making processes to control a hazard within the legal environment. Incentive mechanisms, which consist of a performance measure and a performance reward, induce companies to use control measures. The framework can be used to analyze the effectiveness and efficiency of alternative incentive systems in which companies have to cooperate with partners from other stages of the supply chain.Incentive mechanism, food safety, supply chain control., Agricultural and Food Policy,

Veiligheid verkend: Een empirisch onderzoek naar de determinanten van veiligheid

Safety has been high on the political agenda for several years. Increased police deployment, heavier sentences, various preventive measures to combat truancy, neighbourhood renewal and strengthening integration are just a small selection of the various policies that are frequently mentioned in the debate on the improvement of safety. Important questions are: how effective are these measures and in which situation do they give the best results? Especially in this time of financial cutbacks there is little room and great pressure to spend each Euro as effectively as possible. For this reason, it is very important to know in which way safety can be influenced effectively and which costs this involves. This report is the first in a series of three reports on the effectiveness of the Dutch safety policy. It aims to develop a framework with which questions about its effectiveness can be answered. The research is based on three key principles. Firstly, safety is truly used as a key variable. Intermediate products, such as the number of police reports or the number of recorded or solved crimes, are of secondary importance. Secondly, safety is regarded as the result of social factors and a complex network/chain of safety-related provisions. As yet, little is known about the empirical relationship between safety, social factors and safety policy. Scientific literature provides hardly any clues. Therefore, this research is a valuable addition to the existing scientific knowledge. Thirdly, such framework is only useful if it can be used to conduct empirical research that could lead to specific policy recommendations. This implies that there is a strong emphasis on the operationalisation of certain concepts and the possibility to substantiate them with available data. These three starting points have a high level of ambition. The first report should therefore be primarily seen as an exploration in which the emphasis is placed on an inventory of available data, identifying relevant social factors and determining the effectiveness of police deployment.safety; security; police; effectiveness; public

Origin of Listeria monocytogenes on meat products

Listeria monocytogenes is a relevant food safety hazard in ready to eat products. Inactivation during processing, prevention of recontamination and control of multiplication are the main instruments to secure the safety of meat products. Intensive microbiological monitoring of products and the production environment are valuable tools to assess the level of control in a meat processing plant. During the course of a year all isolates found during hygiene monitoring at a meat processing plant were stored at -70 degrees Celsius. A total of 94 L. monocytogenes isolates have been analyzed by pulsed-field gel electrophoresis (PFGE) and were divided into 30 different types