This thesis is focused on measurement and analysis of dynamic effects on railway turnouts. Two same-type turnouts with different fastening elasticity were chosen. My attention was focused mainly on the crossing part of the turnout, where the highest dynamic impacts occur. The point of the thesis is comparison of the crossing part of turnouts in term of dynamic behaviour and assessment of influence of soft rail pads on spread of dynamic energy through the construction. A part of the thesis is choice of methodology of the measurement and proposal of convenient mathematical apparatus for analysing of the dynamic effects on crossings.

Turnouts (Switches & Crossings) are important components in railway networks, as they provide the necessary flexibility for train operations by allowing trains to change among the tracks. But the turnout’s geometry with discontinuity in rail profiles and lack of transition curve causes additional wear both on track and on vehicle. The main goal of this MSc thesis is to investigate the influence of turnouts on wheel wear of a freight vehicle. This will be obtained by simulations in the commercial MBS software GENSYS. The wheel-rail contact is modelled according to Hertz’s theory and Kalker’s simplified theory, with the FASTSIM algorithm, and the wear calculations are performed according to Archard’s law. Wheel wear is estimated by considering variations in parameters which have effect on wheel-rail contact. All these variations are common in daily rail operation, and they are caused by it, i.e. worn wheel profiles, worn crossing nose and different stiffness of the stock and the switch rails at the beginning of the turnout. Moreover, the wheel wear is calculated for both possible directions which a vehicle can run, the diverging and the straight direction of the turnout. Especially for the straight direction, various running speeds have been tested as the speed limit when the vehicle follows the straight direction is higher than for the diverging part. Running with worn wheel profiles has the greatest impact in terms of increasing the wheel wear, especially on the outer part of wheel tread. In addition, the worn crossing nose results in increased wheel wear in this area. The results of the simulations concerning the different stiffness showed that the wheel wear caused by the contact of wheel and stock rail increases whereas the wear caused by the contact with the switch rail is kept at about the same level or decreases. It is concluded that turnouts have a significant impact on wheel wear, mainly because of the discontinuity in rail geometry and all the investigated parameters increase this impact. Moreover, great differences in wear values for areas close to each other are observed, mainly because of the wear coefficient values chosen in Archard’s wear map.

This thesis analyses how a payment system affects the diffusion of renewable electricity in rural Uganda. A case study is used provided by a start-up company named Pamoja Cleantech. This company is about to sell electricity, which is generated by biomass-based gasification, to a low-income community. Several households are already connected to the established mini-grid while the majority is still not served. A chasm has been identified between the users in the rural village. The reason for this gap between adopters is the high connection fee and a lack of transparent communication. Therefore, diffusion theory has been used to analyse the impact of several payment-related solutions that could close this chasm. First of all, a set of critical factors have been identified concerning general electricity adoption in the case. Those are reliability, trust, transparent communication and satisfying the needs of the local people. Additionally, it has been shown that a payment system, tariffs, and investment costs must satisfy specific requirements in order to be effective, efficient, and positively affect the rate of adoption. These are requirements such as dealing with the cultural incompetence of people being able to save money and to overcome their understanding to have electricity as a status symbol. Therefore an existing technology with its infrastructure is proposed to use: mobile banking. Since this technology has already penetrated Uganda, its convenience to use and satisfaction is high. Additionally, it has advantages such as saving time, security, reliability, and not much space for fraud. This thesis is based on a theoretical framework that is empirically tested and will provide a description of this specific situation in Uganda. Also, it proposes several management recommendations for the company in order to convert adduced threats into opportunities and strengthen their current inclusive business model.

The master’s thesis deals with upgrading of the Holešov railway station. The goal is to design a solution suitable for the capacity for a current traffic and valid legislation. Required are two boarding edges in the length of 130 meters enabling access to persons with reduced mobility and orientation, adjustments or renovation of a station throat triggered by insertion of platforms, maximizing line speed and design of railway superstructure and substructure design including drainage.

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No description available.

Abstract   The aim of this essay is to explain why Caryl Phillips presents Joyce as "the adopted daughter of Africa" at the end of Crossing the River (1993). This will be done by performing a close reading. This essay will focus on Joyce’s actions and behaviour. Aspects of feminism and postcolonial theory will act as the theoretic basis for the analysis. The analysis of Joyce’s character will be put in relation to the whole of Phillips’ “Black Atlantic” narrative and to gender and third wave feminist theories. The analysis will show that Joyce, by breaking racial norms, renouncing her faith, defying her mother, divorcing her husband, and falling in love with Travis, is the person who defines hope in the novel. Her character, together with her son Greer, shows a path to reconciliation between races in the aftermath of colonialism.

Level crossings are a dangerous part of railways, causing several deaths every year. While the safest solution is to remove crossings altogether using bridges or tunnels, this is complicated and cannot be done on a large scale. Many level crossings will therefore continue to exist. To enhance the safety of those crossings, they are equipped with automatic barriers, preventing crossing traffic from entering the track when trains are approaching. Partly due to outdated systems, the Swedish Transport Administration procured a fully integrated and automatic level crossing system aimed to make safety systems more cost efficient. However, it has been stated that the cost of such a system is still high in relation to the number of crossings in the Swedish railway infrastructure. To enhance the scalability of safety systems in level crossings, this research aims to explore the potential of modular systems. Applications of the concept within the railway industry are limited. In addition, previous research perceives the power of modular designs differently. This research was conducted as a case study on level crossings in the Swedish railway infrastructure that is managed by the Swedish Transport Administration. Opportunities with modular systems were identified within the three themes of reducing groundwork costs, improving maintenanc eactivities, and enhancing the replaceability of parts. The study proposes that scalability can be increased by a standardised foundational structure, standardised communication protocols, convenient replacements of modules rather than repairs on-site, shared maintenance activities across systems, and customised testing procedures based on the individual requirements of modules. Different conditions, such as being able to oversee the state of inherent modules and regulations regarding data usage, were also determined to be important for a successful implementation. / Plankorsningar är en farlig del av järnvägar som orsakar flera dödsfall varje år. Även om den säkraste lösningen är att bygga bort dessa helt och hållet genom broar och tunnlar, så är detta ofta komplicerat och inte möjligt i många fall. Många plankorsningar kommer därför att finnas kvar. För att säkerställa säkerheten förses dessa med automatiskt fällande bommar, som hindrar korsande trafik att passera spåret när tåg närmar sig. Till följd av bland annat utdaterade system, har Trafikverket upphandlat ett fullt integrerat och automatiskt bomsystem som ska vara mer kostnadseffektivt än tidigare lösningar. Det har däremot konstaterats att kostnaden för ett sådant system fortfarande är hög i relation till antalet korsningar i den svenska järnvägsinfrastrukturen. För att öka skalbarheten av säkerhetssystem i plankorsningar syftar denna forskning till att undersöka potentialen av modulärt designade system. Tidigare studier är oense om möjligheterna med modulsystem. Därutöver är forskning som applicerar konceptet inom järnvägsbranschen begränsad. Denna undersökning utfördes som en fallstudie inom plankorsningar i den svenska järnvägsinfrastrukturen som hanteras av Trafikverket. Möjligheter med modulsystemidentifierades inom de tre temana minskade kostnader för markarbete, förbättratunderhållsarbete, och ökad utbytbarhet av delar. Studien föreslår att skalbarheten kan ökas genom ett standardiserat fundament, standardiserade kommunikationsprotokoll, smidigt utbytbara moduler istället för reparationer i anläggningen, gemensamma underhållsaktiviteter mellan system, och anpassade tester baserat på kraven i enskilda moduler. Samtidigt framträdde vissa villkor, såsom möjligheten att kunna överse tillståndet i de inneboende modulerna och regleringar gällande dataanvändning, som viktiga faktorer för en lyckad implementation.

Planar graphs have a rich history that dates back to the 18th Century. They form one of the core concepts of graph theory. In computational graph theory, they offer broad advantages to algorithm design and many groundbreaking results are based on them. Formally, a given graph is either planar or non-planar. However, there exists a diverse set of established measures to estimate how far away from being planar any given graph is. In this thesis, we aim at evaluating and improving algorithms to compute these measures of non-planarity. Particularly, we study (1) the problem of finding a maximum planar subgraph, i.e., a planar subgraph with the least number of edges removed; (2) the problem of embedding a graph on a lowest possible genus surface; and finally (3) the problem of drawing a graph such that there are as few edge crossings as possible. These problems constitute classical questions studied in graph drawing and each of them is NP-hard. Still, exact (exponential time) algorithms for them are of high interest and have been subject to study for decades. We propose novel mathematical programming models, based on different planarity criteria, to compute maximum planar subgraphs and low-genus embeddings. The key aspect of our most successful new models is that they carefully describe also the relation between embedded (sub-)graphs and their duals. Based on these models, we design algorithms that beat the respective state-of-the-art by orders of magnitude. We back these claims by extensive computational studies and rigorously show the theoretical advantages of our new models. Besides exact algorithms, we consider heuristic and approximate approaches to the maximum planar subgraph problem. Furthermore, in the realm of crossing numbers, we present an automated proof extraction to easily verify the crossing number of any given graph; a new hardness result for a subproblem that arises, e.g., when enumerating simple drawings; and resolve a conjecture regarding high node degree in minimal obstructions for low crossing number.

Languages occasionally have syntactic constructions that are difficult, if not impossible, to describe using a context-free grammar. One such construction is a crossing dependency. Crossing dependencies have been well studied for Dutch and Swiss German (Huybregts, 1976; Shieber, 1985), and recently for Tagalog (Maclachlan and Rambow, 2003). In this paper I propose that Persian exhibits crossing dependencies. In this SOV language, a light verb construction in the future tense becomes interrupted by a future auxiliary verb, which agrees with its subject in person and number. The future auxiliary also splits passive constructions in a similar manner. These forms present interesting challenges for computational models of language. I will discuss implications of this phenomenon within current formal and linguistic theories.