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Algorithm for inserting a single train in an existing timetableLjunggren, Fredrik, Persson, Kristian January 2017 (has links)
The purpose with this report is to develop a network based insertion algorithm and evaluate it on a real-case timetable. The aim of the algorithm is to minimize the effect that that train implementation cause on the other, already scheduled traffic. We meet this purpose by choosing an objective function that maximizes the minimum distance to a conflicting train path. This ensures that the inserted train receives the best possible bottleneck robustness. We construct a graph problem, which solve with a modified version of Dijkstras algorithm. The complexity of the algorithm is Ο(s^2 t log(s^2 t). We applied the algorithm on a Swedish timetable, containing 76 stations. The algorithm performs well and manage to obtain the optimal solution for a range of scenarios, which we have evaluated in various experiments. Increased congestion seemed to reduce the problem size. The case also show that a solutions robustness decreases with increasing total number of departures. One disadvantage with the algorithm is that it cannot detect the best solution among those using the same bottleneck. We propose a solution to this that we hope can be implemented in further studies.
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Recurrent macroscopic hematuria after anegative investigation – diagnostic yield ofrepeat investigationEliasson, Madeleine January 2021 (has links)
Introduction: Macroscopic hematuria is an important alarm symptom of cancer in theurinary tract. One single episode in patients over the age of 50 fulfills the criteria for referralto the standardized care pathway. Several patients included in the pathway with a negativeresult of the investigation will return with recurrent macroscopic hematuria for repeatinvestigation. Aim: To evaluate the diagnostic yield of repeat investigation in patients presenting withrecurrent macroscopic hematuria after a previous negative investigation and to estimate theincidence of false negative investigations in the standardized care pathway for cancer in theurinary tract. Material and Methods: A retrospective review of medical records was performed at theDepartment of Urology in Örebro County, including all patients investigated in thestandardized care pathway for cancer in the urinary tract during 2016 with a negative result ofthe investigation. Individuals with repeat investigation were identified. Results of theseinvestigations and the time interval between investigations were documented. Results: Repeat investigation was performed in 96 out of 627 patients (15.3%). Two (2.1%)were diagnosed with cancer, at a time interval from initial investigation of 4 and 27 months,respectively. Other results were benign urological conditions (n = 62) and normalinvestigations (n = 30). Conclusions: It appears that few tumors are missed when macroscopic hematuria isinvestigated in the standardized care pathway. We observed a very low number of newlydiagnosed cancers after repeat investigation of recurrent macroscopic hematuria. A moreselective approach regarding repeat investigations should be considered.
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Literary Self-Translation and Self-Translators in Canada (1971-2016): A Large-Scale StudyVan Bolderen, Patricia 28 September 2021 (has links)
This thesis constitutes a first large-scale study of literary self-translators and self-translations in Canada, with self-translation understood as interlinguistic and intertextual transfer where the same legal person is responsible for writing the antecedent and subsequent texts. Three main questions guide this investigation: To what extent is Canada fertile ground for self-translation? What does it mean to self-translate in Canada? Why does self-translation in Canada matter? After situating Canada-based research within broader self-translation scholarship, I engage in a critical analysis of the definition and implications of self-translation and contextualize the theoretical, sociopolitical and methodological rationale for studying Canada and adopting a macroscopic approach to examining self-translations and their writers in this country. The thesis predominantly revolves around self-translation artefacts produced by three groups of writers who self-translated in Canada at least once between 1971 and 2016: 1) those self-translating exclusively between English and French; and those self-translating into and/or out of 2) Spanish; or 3) standard Italian. Exploring the theme of collaboration, I propose a new typology of collaborative self-translation, attempting to account for both process- and product-related considerations. In examining the theme of frequency, I identify self-translators and discuss their relative distribution vis-à-vis language, generation, country of birth and location within Canada; I also map out a conceptual framework for defining and counting self-translation products, proposing new ways of understanding and classifying writers in light of their self-translational productivity. In considering the theme of language, I analyze how writers and their self-translations can be characterized in relation to language variety, language combinations and language directionality. In this thesis, I argue that Canada is a significant hub of heterogeneous self-translational activity, and that large-scale, quantitative and product-oriented study constitutes a useful research approach that can generate rich findings and complement other forms of investigation. The thesis also contains an extensive appendix in which I identify Canadian self-translators and their self-translations.
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Strukturní analýza molekulárních krystalů / Structure analysis of molecular crystalsJaníček, Jakub January 2019 (has links)
Summary: Diploma thesis covers characterization of molecular crystals by X-ray structural analysis. N-carbamimidazoylisonikotinamid and 1-phenylguanidin were chosen, because their potential use in second harmony generation. Their salts with inorganic acids were prepared and determined their structures. Phase transition of 4,6-diaminopyrimidinium nitrate was studied by x-ray diffraction and differential scanning calorimetry. This phase transition is accompanied by thermosalient effect, causing that the crystals jump. Keywords: thermosalient, jumping crystal, X-ray diffraction, non-linear optics, N-carbamimidazoylnikotinamid, 1-phenylguanidin, 4,6diaminopyrmidin.
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Modeling Collective Motion of Complex Systems using Agent-Based Models and Macroscopic ModelsJanuary 2019 (has links)
abstract: The main objective of mathematical modeling is to connect mathematics with other scientific fields. Developing predictable models help to understand the behavior of biological systems. By testing models, one can relate mathematics and real-world experiments. To validate predictions numerically, one has to compare them with experimental data sets. Mathematical modeling can be split into two groups: microscopic and macroscopic models. Microscopic models described the motion of so-called agents (e.g. cells, ants) that interact with their surrounding neighbors. The interactions among these agents form at a large scale some special structures such as flocking and swarming. One of the key questions is to relate the particular interactions among agents with the overall emerging structures. Macroscopic models are precisely designed to describe the evolution of such large structures. They are usually given as partial differential equations describing the time evolution of a density distribution (instead of tracking each individual agent). For instance, reaction-diffusion equations are used to model glioma cells and are being used to predict tumor growth. This dissertation aims at developing such a framework to better understand the complex behavior of foraging ants and glioma cells. / Dissertation/Thesis / Doctoral Dissertation Applied Mathematics 2019
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Mobilization of Entrapped Gases in Quasi-Saturated Groundwater Systems Contaminated with Biofuel AdditivesElliott, Claire January 2020 (has links)
Biofuel additives have been designed to reduce vehicular emissions to the atmosphere to limit the effects of greenhouse gases on global climate change. The chemical properties of common biofuel additives exhibit ideal characteristics for use in gasoline and diesel, while limiting emissions from exhaust. As biofuel additives begin to be administered regularly to gasoline and fuel sources, the compounds will appear in spill sites, posing a risk to groundwater sources. The interactions that occur between common biofuel additives and trapped gases below the water table were analyzed in this work to further understand the potential consequences on quasi-saturated groundwater zones. The behaviour of trapped gases contaminated with different biofuel additives were analyzed in laboratory experiments conducted in a two-dimensional flow cell to demonstrate the mechanisms of gas flow through a capillary barrier resulting from modified interfacial properties in the presence of a chemical surfactant. Contamination of gas-fluid interfaces by applied biofuel additives at the pore scale resulted in the breakthrough of gas through the capillary barrier. Gas migration terminated at a critical pool height proportional to the reduction in interfacial tension induced by the administered biofuel additives. To further demonstrate the relationship between interfacial tension and critical gas pool height, an interfacial tension-macroscopic invasion percolation model was developed to simulate the transport mechanisms and behaviours of gas flow when an immobile pool is contaminated with 1-Butanol. The findings in this study provide a fundamental understanding of the mechanisms and behaviours of gas mobilization in the presence of common biofuel additives. / Thesis / Master of Science (MSc) / The use of biofuel additives in gasoline and diesel fuels has become an attractive alternative to fully petroleum-based fuels to reduce the release of vehicular greenhouse gases to the atmosphere. As fuel spills and storage tank leaks continue to be a primary source of groundwater contamination, the appearance of biofuel additives in contaminated systems will appear below the subsurface as they continue to be administered to modern gasoline and diesel fuels. This work investigated the consequences of biofuel contamination of groundwater systems containing gas trapped within pore spaces through the use of laboratory experiments and numerical modelling. Contamination of these systems with different biofuel additives displayed a similar response, in which gas had mobilized from within pore spaces and released to the atmosphere. Mobilization of trapped gas in groundwater can alter the primary hydraulic properties that characterize a particular hydrogeologic system.
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A methodology of aggregating discrete microscopic traffic data for macroscopic model calibration and nonequilibrium visual detection purposesBlythe, Kevin S. January 1991 (has links)
No description available.
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Macroscopic Coupling Conditions with Partial Blocking for Highway RampsSomers, Julia Marie January 2015 (has links)
We consider the Lighthill-Whitman-Richards traffic model on a network consisting of a highway with an off ramp, connected by a junction. We compare the known coupling conditions for the evolution of traffic at the junction and suggest a novel improvement to the existing conditions. That is, we resolve the spurious effects that arise in standard models, namely clogging of the main highway and vehicle destination changes. We achieve this by tracking vehicle density buildup in the form of a queue, which is modeled by an ODE. We define the solution to the Riemann problem at the junction using the supply and demand functions. The numerical approximation is carried out using a modified Godunov scheme, adjusted to take into account the effects of an emptying queue. Exact and numerical comparisons of the model with existing models verify that the number of vehicles who wish to exit are preserved and the nonphysical clogging of the main highway does not occur. / Mathematics
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Regulating Traffic Flow and Speed on Large Networks: Control and Geographical Self Organizing Map (Geo-SOM) ClusteringElouni, Maha 09 June 2021 (has links)
Traffic growth and limited roadway capacity decrease traveler mobility and increase traffic congestion and fuel consumption. Traffic managers employ various control techniques to mitigate the aforementioned problems. One well-known network-wide control strategy is perimeter control (or gating). Perimeter control is based on the Network Fundamental Diagram (NFD). NFD-based perimeter control techniques are used to solve congestion problems in transportation networks. One well-known method used in the literature is Proportional Integral Control (PIC). PIC solves the congestion problem, but suffers from sensitivity to parameter tuning and the need for model linearization. A weather-tuned perimeter control (WTPC) and a jam density-tuned perimeter controller (JTPC) were developed to cope with parameter sensitivity for different weather conditions and jam densities, respectively. In an attempt to overcome PIC problems, a sliding mode controller (SMC) was developed. SMC does not require model linearization and parameter tuning. It is also robust to varying demand patterns. SMC computes the flow that needs to enter a protected network and converts it to corresponding traffic signal timings to achieve the desired control strategies. Another approach to implementing the sliding mode controller is to control vehicle speeds on the links entering the protected network. Coupling speed harmonization (SH) with sliding mode control (SMC), an SMC-SH was developed and implemented in the INTEGRATION microscopic traffic simulator. The mentioned controllers are all tested on a mid-size grid network replicating downtown Washington DC. SMC-SH improved different performance metrics on the whole grid network compared to the no control case. Specifically, it improved average travel time, total delay, stopped delay, fuel consumption, CO2 emissions by 17.27%, 18.18%, 12.76%, 5.91%, and 7.04%, respectively. In order to test the SMC-SH on a real large-scale network, the downtown Los Angeles (LA) network is used. The LA network is known for its congested freeways, so a development of a Freeway-SMC-SH controller is performed and tested. It shows good results in improving the performance not only of freeways, but also the overall LA network performance. Particularly, the network-wide average travel time, total delay, stopped delay, fuel consumption and CO2 emissions improved with respect to the no control case by 12.17%, 20.67%, 39.58%, 2.6%, and 3.3%, respectively. An identification of a homogeneously congested area is needed to apply SMC-SH on LA roads (not freeways). The geographical self organizing maps (GeoSOM) clustering algorithm is applied and tested on the LA network. The clustering goal is to identify a geographically connected region with small density variance. GeoSOM is able to achieve that objective with better performance than the state-of-the-art Kmeans and DBSCAN clustering algorithms. The enhancements reached up to 15.15% for quantization error, 61.05% for spacial quantization error, and 43.96% for variance. Finally, the SMC-SH is tested on the protected region of the LA network identified by the GeoSOM algorithm. SMC-SH succeeds in improving network-wide vehicle travel time, total delay, stopped delay, fuel consumption and CO2 emissions by 6.25%, 9.4%, 16.47%, 1.7%, and 2.19%, respectively. / Doctor of Philosophy / Road congestion causes vehicular delays and increases travel time and fuel consumption. The goal of the research is to prevent or relieve traffic congestion in a network. That region that we attempt to address is termed the congested network or the protected network (PN). One way to solve the traffic jam problem is to set up gates on the PN borders so that the number of vehicles that enter the network is limited, and consequently traffic jams do not occur. However, the number of vehicles should not be limited too much to avoid overcrowding outside the PN. The developed controller calculates the right number of cars that should enter the network in order to improve the performance inside and outside the PN. The first way to apply the controller commands is to adjust traffic signal timings at the traffic signals located along the PN border. The second way (called SMC-SH) is to adjust the speed of the vehicles entering the network through these gates. In the first part of the work, all the controllers are implemented and tested in a mid-size grid network. In the second part of the work, the goal is to implement the controller on the real large-scale Los Angeles (LA) network. Since the LA network suffers from congestion on freeways, a freeway controller is developed and tested. It does not only succeed in reducing traffic jams on freeways, but also enhances the overall LA network traffic performance. In order to apply the SMC-SH controller on the LA network, we identify homogeneously congested regions. GeoSOM clustering is implemented to achieve this goal and compared to other clustering methods, and is shown to outperform them. Finally, the SMC-SH controller is tested on the congested region of LA, and succeeds in reducing travel time, total delay, and fuel consumption for the LA network.
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Incorporating Socio-Economic Factors in Traffic Management and ControlHan, Rubi 01 October 2015 (has links)
Traffic Congestion is a critical problem in large urban areas. In this thesis, six different control strategies aiming to alleviate congestion are performed through TRANSIMS simulation in the city of Alexandria. Main objective of this thesis is to study and explore the impacts of these control strategy in terms of system performance. Macroscopic Fundamental Diagrams has been used during research to present traffic movement and evaluate traffic performance. This thesis also look at the outcome of each strategy at different household income group in the city. The attention are drawn to the importance of taking socio-economic impact in traffic management decisions. Some of the control strategies presented in this thesis have different impacts on different income groups in the city, while other control strategies have similar impacts (negative, or inconclusive) on different groups in Alexandria city. The thesis gives the conclusions on the impact of selecting different signal control strategies. / Master of Science
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