Some results on heuristical algorithms for shortest path problems in large road networks

This thesis studies the shortest path problem in large road networks. The classical algorithm for networks with non-negative edge weights is due to Dijkstra and has a worst-case performance of O ( |E |+ |V |log |V |) using a simple priority queue as data structure for temporarily labeled nodes. We present a new, so-called tree heuristic, which is based on the similarity of shortest path trees and which can be used to speed up the shortest path search especially in practical applications like microscopic simulation of traffic or route guidance systems. Instead of searching a path in the original network, the tree heuristic partitions the network into classes of about equal size and constructs a special searchgraph for each class. On a test road network of about one million nodes the tree heuristic outperforms Dijkstra\'s algorithm by a factor of more than three with respect to runtime and about seven with respect to permanently labeled nodes where the found paths can be expected to have a relative error below 1%, if the starting and end node are not too close to each other. We also analyze the A -algorithm with overdo-factor, originally devised for Euclidean networks and derive an interval [1.... 27......,5] from which an optimal overdo-factor should be chosen in practical applications. Finally we give an algorithm which calculates edge tolerances for a shortest path and which can be used to generate reasonable alternative routes to the exact shortest path

An ethnography of deportation from Britain

In the past decades, immigration policies have been refined to broaden eligibility to deportation and allow easier removal of unwanted foreign nationals. Yet how people respond to a given set of policies cannot be fully anticipated. Studying the ways people interpret, understand and experience policies allows for a better understanding of how they work in practice. Drawing on ethnographic fieldwork conducted in London, this thesis examines experiences of deportation and deportability of migrants convicted of a criminal offence in the UK. It finds that migrants’ deportability is experienced in relation to official bodies, such as the Home Office, the Asylum and Immigration Tribunal, Immigration Removal Centres and Reporting Centres, and becomes embedded in their daily lives, social relations and sense of self. The lived experience of deportation policies emphasizes the material and human costs associated with deportation and highlights its punitive and coercive effects. Deportability marks migrants’ lives with chronic waiting and anxiety. As a result, migrants awaiting deportation make use of four coping strategies: enduring uncertainty, absenting and forming personal cues (Ågård & Harder 2007), and also re-imagining their futures. In turn, migrants’ understandings of their own removal appear incompatible with open political action and with the broader work of Anti-Deportation Campaign support groups. Resistance is thus enacted as compliance with state controls (such as surveillance and immobility), which are perceived as designed to make them fail, rendering them ever more deportable. By enduring this power over them, migrants are resisting their removal and fighting to stay. The thesis concludes that the interruption of migrants’ existence in the UK is effected long before their actual removal from the territory. It is a process developing from the embodiment of their deportability as their present and future lives become suspended by the threat of expulsion from their residence of choic

Why are Scandinavians so happy?

Perhaps somewhat surprising to many in central Minnesota, Scandinavian societies are ranked as having the happiest people in the world. Long-term longitudinal studies such as Development, Freedom, and Rising Happiness: A Global Perspective (1981-2007) by Inglehart, Foa, Peterson and Welzel of the University of Leicester, and recent research reported by the United Nations Sustainable Development Solutions Network in its World Happiness Report 2013 , edited by Helliwell, Layard & Sachs, consistently come to the conclusion that Scandinavians are the happiest people in the world. Why? How is this possible? What can we learn from them

Nutrients and contaminants in processed small indigenous fish species from Ghana : Implications for food and nutrition security

The prevalence of malnutrition is increasing globally, along with the need to access nutritious, safe and sustainable foods. Fish are known as a rich source of protein, essential fatty acids and micronutrients, and including small indigenous fish species (SIS) in the diet has been proposed as a strategy towards alleviating malnutrition. SIS are a central part of the diet in Ghana and are commonly preserved by smoking or drying. Still, stunting and micronutrient deficiencies among young children persist. Furthermore, the livelihoods of millions of Ghanaians depend on the small-scale fisheries, from fishers and traders, to processors and market women. Having reliable data on SIS availability and food composition data on nutrients and contaminants in SIS is therefore essential to assess its potential role towards improving food and nutrition security (FNS) in Ghana. The broad aim of this thesis was to explore how SIS contribute to FNS in Ghana, while specific aims of the study were addressed in three articles: Firstly, we aimed to assess the current challenges and opportunities in the Ghanaian fish value-chain through a literature review, and assess how future strategies can strengthen the role of SIS towards enhancing FNS. Secondly, we aimed to determine the nutritional quality and food safety of six commonly consumed processed SIS from Ghana by analyzing key nutrients, heavy metals, PAHs and microbial contamination. Lastly, we aimed to determine nutrient and contaminant distribution in tissues of smoked European anchovy and assess how exposure potentially affects vulnerable population groups. Through a narrative literature review, we found that uncertainties in fish availability and access are challenging the sustenance of the millions of Ghanaians involved in the small-scale fisheries value-chain. The synthesized data further indicated that fish utilization is constrained by inadequate young child feeding practices and food safety issues, while seasonality and climate changes are hindering stability. To assess the nutritional quality and food safety of commonly consumed SIS, samples of smoked European anchovy (Engraulis encrasicolus) bigeye grunt (Brachydeuterus auritus), round sardinella (Sardinella aurita), African moonfish (Selene dorsalis), dried/smoked West African (WA) pygmy herring (Sierrathrissa leonensis) and salt dried tilapia (Tilapia spp.) were collected from fish markets in five different regions in Ghana. Samples of European anchovy were divided into subsamples of whole fish, heads and skin and samples without heads and skin. Using accredited methods, composite samples of SIS were analyzed for nutrients (crude protein and fat, fatty acids, key vitamins, minerals, and trace elements), microbiological quality and contaminants (PAH4 and heavy metals). The marine SIS, tissues of European anchovy and WA pygmy herring had the potential to significantly contribute to the nutrient intakes of essential micronutrients, including Fe, Zn, I, Se, Ca, vitamin D, vitamin B12 and ω-3 polyunsaturated fatty acids (PUFAs), while tilapia was the least nutrient dense. High levels of Fe, Hg, Pb and Cd were detected in certain SIS and tissues and PAH4 in all smoked fish samples reached high concentrations, up to 1,300 μg/kg. In a scenario referencing Ghanaian infants and toddlers (6-23 months), it was determined that consuming smoked SIS will entail potential risk in terms of Cd and PAH-exposure. In this thesis, we determined that processed SIS contain high levels of nutrients and represent a promising food-based approach to alleviate micronutrient deficiencies in Ghana. However, the current levels of certain heavy metals and PAHs above recommended limits may entail potential consumer risk. Generating data on dietary intakes of SIS, identification of contamination sources and improvement of processing methods are therefore warranted in order to secure safe utilization of SIS in Ghana. Furthermore, the current lack of focus on fish and FNS in scientific literature and legislation highlights the need for fish to be given greater priority, which is essential to secure the sustenance of Ghana’s small-scale fisheries.Doktorgradsavhandlin

XXXIX. On the second spectrum of hydrogen

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Detecting pedestrians intending to enter a crosswalk using a HMM tracker and a novel predictor

There is a demand for a more fluent and more efficient traffic. This can be achieved through more intelligent traffic light control. This thesis presents theory and an application in which people are tracked and their intentions to cross a crosswalk is predicted with a novel prediction algorithm based on Markov theory. The background segmentation and tracking algorithms was based on already known cross-correlation and HMM-methods. Based on the relatively small amount of training data the result for the novel predictor detecting persons "entering the crosswalk" for two different setups, a straight and a four way crossing, is 70% and 55% true positives with 5% and 2% false positives. For detection of someone that is "not entering the crosswalk" when there is a person in the area is 90% and 85% true positives with 15% and 25% false positive. The results achieved are good enough as a proof of concept that the theories are worth investigating further for these kind of applications. However, a lot of work would still be required before this is robust enough to be in a real traffic application

Influence of the cutting tool compliance on the workpiece surface shape in face milling of workpiece compounds

A currently common method to design high-performance workpieces is to combine two or more materials to one compound. In this way, workpieces can be composed of the most qualified materials according to local loads. When machining high-performance workpiece compounds high quality requirements concerning the accuracy of dimension and shape as well as surface roughness must be fulfilled. However, in case of parallel machining, where the cutting edge moves from one material into the other within one cutting tool revolution, unequal cutting properties have a significant negative influence on tool wear and surface quality. Shape deviations of the surface occur, which are not detected when machining the single materials. The four most significant shape deviations that affect the workpiece quality are the material height deviation, transition deviation at the material joint as well as surface roughness deviation. This paper contains new approaches on the prediction of the surface shape that is generated by a face milling process. The focus is on the transition deviation at the material joint. It arises from a force impulse that is applied on the cutting tool and creates a wavy surface on the workpiece. This shape is predicted via cutting force prediction as well as frequency response analysis of the cutting tool and workpiece in relation to different tool holders. Furthermore, deviations between calculated surface shapes and measured surface shapes subsequent to machining tests are evaluated.DFG/DE 447/113-

Road traffic crash circumstances and consequences among young unlicensed drivers: A Swedish cohort study on socioeconomic disparities

<p>Abstract</p> <p>Background</p> <p>Young car drivers run a higher risk of road traffic crash and injury not only because of their lack of experience but also because of their young age and their greater propensity for adopting unsafe driving practices. Also, low family socioeconomic position increases the risk of crash and of severe crash in particular. Whether this holds true for young unlicensed drivers as well is not known. Increasing attention is being drawn to the prevalence and practice of unlicensed driving among young people as an important contributor to road traffic fatalities.</p> <p>Methods</p> <p>This is a population-based cohort study linking Swedish national register data for a cohort of 1 616 621 individuals born between 1977 and 1991. Crash circumstances for first-time road traffic crash (RTC) were compared considering licensed and unlicensed drivers. The socioeconomic distribution of injury was assessed considering household socioeconomic position, social welfare benefits, and level of urbanicity of the living area. The main outcome measure is relative risk of RTC.</p> <p>Results</p> <p>RTCs involving unlicensed drivers were over-represented among male drivers, suspected impaired drivers, severe injuries, crashes occurring in higher speed limit areas, and in fair road conditions. Unlicensed drivers from families in a lower socioeconomic position showed increased relative risks for RTC in the range of 1.75 to 3.25. Those living in rural areas had an increased relative risk for a severe RTC of 3.29 (95% CI 2.47 - 4.39) compared to those living in metropolitan areas.</p> <p>Conclusions</p> <p>At the time of the crash, young unlicensed drivers display more risky driving practices than their licensed counterparts. Just as licensed drivers, unlicensed young people from low socioeconomic positions are over-represented in the most severe injury crashes. Whether the mechanisms lying behind those similarities compare between these groups remains to be determined.</p