Switches and crossings are vital components of the railway network. Obstacles to the smooth functioning of these components could result in delays and network traffic. Given the geographical location of Sweden, snow is one of the major obstacles for the switches. The presence and hardening of snow act as an obstacle to the movement of the switch rail, thus hindering its function. Electrically heated switches melt and clear the snow for movement of the switch rail. They typically operate at a power level of 10 kW–30 kW. With 6800 switches operational in Sweden, the potential for energy savings is huge. This master thesis intends to investigate the possibility of reducing energy consumption through insulating a side of the rail. To achieve that, a comprehensive transient conjugate heat transfer analysis is carried out using CFD simulations. The initial refinement of the measured data highlighted the uncertainties in them, and which shaped the course of the thesis. The analysis of these uncertainties gave critical insights and led to useful recommendations for future work. The fluid-solid interactions between the rail and flow of air and their impact on transient heat loss have been analyzed to gain critical insights regarding the choice of side of implementation of insulation. The validation of the model at lower electrical power levels threw light on the dire requirement of numerical modeling of snow melting, which happens at the higher power levels of the heating element. One of the critical observations made after the implementation of the insulation is the reduction in the temperature of the heating element, which leads us to conclude that the insulation not only saves energy but also prolongs the life of the heating element by reducing thermal fatigue. / Växlar och korsningar är viktiga komponenter i järnvägsnätet. Om dessa komponenter inte fungerar smidigt kan det resultera i förseningar och avbruten nätverkstrafik. Med tanke på Sveriges geografiska läge är snö ett av de största hindren för växlarna. Snö och hårt packad snö kan hindra spårväxelns rörelse och funktion. Elektriskt uppvärmda spårväxlar smälter bort snön så att spårväxeln kan fungera. Spårväxlarna har vanligtvis en effektnivå på 10 kW - 30 kW. Med 6 800 växlar i drift i Sverige är potentialen för energibesparingar är enorm. Denna masteruppsats syftar till att undersöka möjligheten att minska energiförbrukningen genom att isolera en sida av rälsen. För att uppnå detta utförs en omfattande transient konjugerad värmeöverföringsanalys med hjälp av CFD-simuleringar. Den inledande dataförädlingen av mätdata belyste osäkerheterna i datan vilket formade det fortsatta arbetet med avhandlingen. Analysen av dessa osäkerheter gav kritiska insikter och användbara rekommendationer för framtida arbete. Fluid - solid-interaktionerna mellan skenan och luftflödet och deras inverkan på den transienta värmeförlusten har analyserats för att få kritiska insikter om valet av sida för isolering. Valideringen av modellen vid lägre effektnivåer kastade ljus över det akuta behovet av numerisk modellering av snösmältningen som sker vid värmeelementets högre effektnivåer. En av de kritiska observationerna som gjordes efter implementeringen av isoleringen är minskningen av värmeelementets temperatur, vilket drar slutsatsen att isoleringen inte bara sparar energiförbrukningen utan också förlänger elementets livslängd genom att minska den termiska utmattningen.

No description available.

[pt] O rebaixamento e controle das águas subterrâneas são atividades implementadas e monitoradas de forma contínua ao longo da vida dos projetos de mineração subterrânea ou a céu aberto. A implementação apropriada e eficiente destas atividades depende de estudos hidrogeológicos de grande porte, que permitem avaliar os sistemas de controle mais adequados. A procura da eficiência técnico-econômica destes processos demanda análises numéricas de fluxo tridimensionais de toda a região em estudo, caracterizada por profundas e complexas estratificações de materiais permeáveis abaixo do lençol freático, como normalmente abrangem projetos de mineração, onde as soluções analíticas não podem mais ser aplicadas. O presente trabalho de pesquisa contribui na melhor compreensão das formulações numéricas que representam o comportamento do fluxo subterrâneo, através de dois estudos de caso, o primeiro em uma mina subterrânea e segundo em uma mina superficial. No caso da mina subterrânea foram incorporadas feições cársticas através de elementos discretos 1D dentro de um modelo tridimensional de elementos finitos com o intuito de representar caminhos preferenciais de fluxo. Foram discutidas as vantagens de incorporar tais feições de forma explicita, quantificando o fluxo que passam por estas, que alimentam à mina através de conexões diretas com um rio adjacente. Estes elementos discretos permitem uma representação mais realista do meio hidrogeológico e ao mesmo tempo, uma avaliação mais aprimorada dos efeitos no comportamento do fluxo subterrâneo devido à impermeabilização superficial do rio, como a solução mais coerente para este problema de infiltração. Também foi elaborado um modelo hidrogeológico conceitual para representar o comportamento hidrogeológico de uma mina a céu aberto, desenvolvendo uma sistemática de uso adequado das condições de contorno e de restrição, a calibração deste modelo e a verificação de diferentes cenários de fluxo, como resultado da incorporação das diferentes técnicas de controle das águas avaliadas em regime transiente, que abrange poços de bombeamento, paredes cut-off assim como ponteiras filtrantes e drenos horizontais. As diferentes técnicas modeladas mostraram resultados satisfatórios, sendo que arranjos de várias técnicas, configuradas de forma localizada, resultam ser mais recomendáveis e eficientes para tratar problemas particulares. / [en] Dewatering and groundwater control are activities continuously implemented and monitored throughout the duration of underground mining or open pit projects. The proper and efficient implementation of these activities depends on large hydrogeological studies, for assessing the most appropriate control systems. The demand for technical and economic efficiency of these processes requires three-dimensional flow numerical analysis of the entire study area, characterized by deep and complex stratifications of permeable materials below the water table, as usually cover mining projects, where analytical solutions cannot be applied. The present research contributes to a better understanding of the numerical formulations that represent the behavior of groundwater flow via two case studies—the first in an underground mine and the second in a surface mine. In the case of the underground mine, 1D discrete elements were incorporated within a finite-three dimensional model in order to represent preferential flow paths. The advantages of incorporating such features explicitly to quantify the flow passing through them, that feed the mine through direct connections with an adjacent river, were discussed. The use of discrete elements allows for a more realistic representation of the hydrogeological environment and, at the same time, a more refined assessment of the effects on the behavior of groundwater flow due to surface sealing of the river, as the most coherent solution to this infiltration problem. Furthermore, a conceptual hidrogeologic model representing the hydrogeological behavior of an open pit mine was created, developing a system of the appropriate use of boundary and constraint conditions, calibrating the model and verifying different flow scenarios, as a result of the incorporation of different water control techniques assessed in transient regime, such as covering pumping wells, cut-off walls as well as wellpoints and horizontal drains. The different techniques modeled showed satisfactory results, with various arrangements of techniques configured in a localized form resulting in the most desirable and efficient treatments for particular problems.

This work describes the implementation of a novel dynamic Arbitrary Lagrangian Eulerian (ALE) formulation for the simulation of pavement structures loaded by rolling tires in a finite element framework. The proposed formulation enables the simulation of dynamic effects like acceleration, deceleration and variation of the wheel load on the pavement. The ALE scheme is described for a hyperelastic St. Venant-Kirchhoff material capable of finite deformations. With the adoption of this dynamic ALE formulation, a significant improvement in terms of speed and efficiency of the simulation is achieved in comparison to a classical transient Lagrangian formulation. This is primarily because only the relevant portion of the mesh around the applied load needs to be discretized and simulated. Another benefit is that a cumbersome moving load formulation does not need to be implemented. The results show satisfactory agreement with a conventional Lagrangian simulation with a moving load.

Ever increasing demand for electricity, exploitation of large hydro and nuclear power at remote location has led to power evacuation by long EHV/UHV transmission systems. This thesis concentrates on transient analysis of EHV/UHV transmission systems for improved planning and protection. In this thesis, the uncontrolled and controlled switching methods to limit the switching surges during energization of 765kV and 1200k VUHV transmission lines are studied. The switching surge over voltages during the energization of series compensated line are compared with uncompensated line. A Generalized Electromagnetic Transients Program has been developed. The program incorporates specific models for studying the effectiveness of various means for control of switching surge over voltages during UHV transmission line energization and also simulation of various types of faults. Since power grids may adopt next higher UHV transmission level 1200kV, these studies are necessary for insulation coordination as well as transmission line protection relay settings. A new fault detection/location technique is presented for transmission line using synchronized fundamental voltage and current phasors obtained by PMUs at both ends of line. It is adaptive to fault resistance, source impedance variation, line loading and fault incidence angle. An improved Discrete Fourier Transform (DFT) algorithm to estimate and eliminate the decaying dc component in a fault current signal is proposed for computing the phasors. The settings for digital distance relays under different operating conditions are obtained. The relay should operate faster and be more sensitive to various faults under different conditions without loosing selectivity. An accurate faulted transmission line model which considers distributed shunt capacitance has been presented. The relay trip boundaries are obtained considering transmission line model under realistic fault conditions. For different loading conditions ideal relay characteristic has been developed. The obtained trip boundaries can be used for proper settings of practical relay. An adaptive relaying scheme is proposed for EHV/UHV transmission line using unsynchronized/synchronized fundamental voltage and current phasors at both ends of line. For fault location, the redundancy in equations is achieved by using two kinds of Clarke’s components which makes the calculations non-iterative and accurate. An operator for synchronization of the unsynchronized measurements is obtained by considering the distributed parameter line model. The distance to fault is calculated as per the synchronized measurements. Support Vector Machine(SVM) is used for high speed protection of UHV line. The proposed relaying scheme detects the fault and faulted phase effectively within few milli seconds. The current and voltage signals of all phases at the substation are fed to SVM directly at a sampling frequency of 1.0kHZi.e20 samples/cycle . It is possible to detect faulted phase with in 3msec, using the data window of 1/4th cycle. The performance of relaying scheme has been checked with a typical 765kV Indian transmission System which is simulated using the developed EMTP.

[pt] Este trabalho apresenta um novo modelo térmico analítico que acopla poço e reservatório, constituído por um sistema combinado de reservatório, revestimento e coluna de produção. As soluções analíticas consideram fluxo monofásico de fluido pouco compressível em um reservatório homogêneo e infinito e fornecem dados transitórios de temperatura e pressão ao longo do poço para testes de fluxo e de crescimento de pressão, considerando efeitos Joule-Thomson, de expansão adiabática, de condução e convecção. A massa específica do fluido é modelada como função da temperatura e a solução analítica faz uso da transformada de Laplace para resolver a equação diferencial de fluxo de calor transiente, assumindo o termo aT⁄az totalmente transiente. Com relação à análise de transientes de pressão (PTA), dados de pressão impactados por variações térmicas podem levar à interpretação de falsas heterogeneidades geológicas, pois a perda de calor durante a estática proporciona um aumento da pressão exercida pela coluna de fluido, devido ao incremento de sua massa específica, além de uma contração da coluna de produção, provocando uma mudança na posição do registrador. Esses efeitos podem fazer com que um reservatório homogêneo seja erroneamente interpretado como um reservatório de dupla porosidade, resultando em conclusões inválidas para a modelagem geológica. Os resultados deste trabalho são comparados com a resposta de um simulador comercial não-isotérmico e impactos nas interpretações são extensivamente investigados. Adicionalmente, um estudo de caso de campo é fornecido para validar as soluções analíticas propostas. Comparado à Literatura, o modelo proposto fornece perfis transientes de temperatura mais acurados. / [en] This work presents a new coupled transient-wellbore/reservoir thermal analytical model, consisting of a reservoir/casing/tubing combined system. The analytical solutions consider flow of a slightly compressible, single-phase fluid in a homogeneous infinite-acting reservoir system and provide temperature- and pressure-transient data for drawdown and buildup tests at any gauge location along the wellbore, accounting for Joule-Thomson, adiabatic fluid-expansion, conduction and convection effects. The wellbore fluid mass density is modeled as a function of temperature and the analytical solution makes use of the Laplace transformation to solve the transient heat-flow differential equation, accounting for a rigorous transient wellbore-temperature gradient aT⁄az. Regarding pressure transient analysis (PTA), thermal impacted pressure data may lead to the interpretation of false geological heterogeneities, since the heat loss during the buildup period provides an increase in the pressure exerted by the wellbore-fluid column, due to an increase in the oil mass density, and a change in tubing length, consequently causing a change in the gauge location. These effects can make a homogeneous reservoir be wrongly interpreted as a double-porosity reservoir, yielding invalid conclusions to geological modeling. Results are compared to the response of a commercial non-isothermal simulator and thermal impacts on PTA interpretations are thoroughly investigated. In addition, a field case study is also provided to verify the proposed analytical solutions. The proposed model provides more accurate transient temperature flow profiles along the wellbore when compared to previous models in Literature.

Music analysis and source separation have become important and allied areas of research over the last decade. Towards this, analyzing a music signal for important events such as onsets, offsets and transients are important problems. These tasks help in music source separation and transcription. Approaches in source separation too have been making great strides, but most of these techniques are aimed at Western music and fail to perform well for Indian music. The fluid style of instrumentation in Indian music requires a slightly modified approach to analysis and source separation. We propose an onset detection algorithm that is motivated by the human auditory system. This algorithm has the advantage of having a unified framework for the detection of both onsets and offsets in music signals. This onset detection algorithm is further extended to detect percussive transients. Percussive transients have sharp onsets followed closely by sharp offsets. This characteristic is exploited in the percussive transients detection algorithm. This detection does not lend itself well to the extraction of transients and hence we propose an iterative algorithm to extract all types of transients from a polyphonic music signal. The proposed iterative algorithm is both fast and accurate to extract transients of various strengths. This problem of transient extraction can be extended to the problem of harmonic/percussion sound separation(HPSS), where a music signal is separated into two streams consisting of components mainly from percussion and harmonic instruments. Many algorithms that have been proposed till date deal with HPSS for Western music. But with Indian classical/film music, a different style of instrumentation or singing is seen, including high degree of vibratos or glissando content. This requires new approaches to HPSS. We propose extensions to two existing HPSS techniques, adapting them for Indian music. In both the extensions, we retain the original framework of the algorithm, showing that it is easy to incorporate the changes needed to handle Indian music. We also propose a new HPSS algorithm that is inspired by our transient extraction technique. This algorithm can be considered a generalized extension to our transient extraction algorithm and showcases our view that HPSS can be considered as an extension to transient analysis. Even the best HPSS techniques have leakages of harmonic components into percussion and this can lead to poor performances in tasks like rhythm analysis. In order to reduce this leakage, we propose a post processing technique on the percussion stream of the HPSS algorithm. The proposed method utilizes signal stitching by exploiting a commonly used model for percussive envelopes. We also developed a vocals extraction algorithm from the harmonic stream of the HPSS algorithm. The vocals extraction follows the popular paradigm of extracting the predominant pitch followed by generation of the vocals signal corresponding to the pitch. We show that HPSS as a pre-processing technique gives an advantage in reducing the interference from percussive sources in the extraction stage. It is also shown that the performance of vocal extraction algorithms improve with the knowledge about locations of the vocal segments. This is shown with the help of an oracle to locate the vocal segments. The use of the oracle greatly reduces the interferences from other dominating sources in the extracted vocals signal.

The Master Thesis performs search concerning advanced small and medium power light-water reactors’ designs, including different possibilities to gain a license for their development and operation. The work covers the principal theory about the area of neutronics calculations, principal equations and simplifications. There are several different methods for solution of neutronics calculations. The thesis gives an overview of two principal groups of codes – deterministic methods and Monte Carlo method. The survey shows computational codes examples based on mentioned methods. The computational code PARCS is chosen for further study, which contained description of the input and output file, process of the model creation and conditions for neutronics calculation the of selected reactor design. Based on these facts, the transient calculation has been prepared within the thesis. Thee analyses are described – reactor emergency shutdown, reactor shutdown with stuck group of control and emergency shutdown rods and reactor shutdown with faulty reaction of emergency shutdown rods.

[pt] Modelos analíticos que descrevam o comportamento da pressão são de extrema utilidade na área de avaliação de formações e caracterização de reservatório, pois eles fornecem estimativas sobre diversos parâmetros do reservatório. Este trabalho tem dois objetivos principais: primeiro, estender a solução existente para testes de injetividade e falloff em reservatórios com uma camada e poços horizontais de modo que ela possa ser aplicada também em formações multicamadas com poços horizontais multirramificados. Além disso, este trabalho aplica funções impulso para obter uma formulação alternativa para testes de injetividade em reservatórios estratificados com poços verticais e formações com uma camada e poços horizontais. / [en] Analytical models that describe the pressure behavior are extremely useful for pressure transient analysis and reservoir characterization as they provide estimates of reservoir parameters. This work has two main goals: first, to extend the existing solutions for injectivity/falloff tests in single-layer formations with horizontal wells so that they can be applied to multilayer stratified reservoirs with multilateral horizontal wells. Furthermore, this work applies impulse functions to obtain an alternative formulation for injectivity tests in multilayer commingled formations with vertical wells and single-layer reservoirs with horizontal wells.

[pt] Teste de injetividade é uma técnica convencional em engenharia de reservatórios, utilizada para a recuperação de óleo em reservatórios e avaliação de formações. Geralmente utiliza-se água como fluido injetado, que resulta em um deslocamento do óleo presente devido ao aumento da pressão nos poros. Durante o teste, a resposta de pressão medida fornece diversas informações sobre os parâmetros do reservatório, tal como dados de permeabilidade. Desta forma, pesquisadores têm se dedicado em encontrar equações matemáticas que modelam a resposta de pressão desses testes com objetivo de gerenciamento e manutenção preditiva do reservatório. Neste trabalho, apresentamos uma nova solução analítica para a análise de testes de injetividade, que combina a técnica de convolução pressão-pressão com um modelo radial composto de duas zonas. Essa solução permite avaliar o teste de injetividade mesmo na ausência de dados precisos de vazão, uma vez que a convolução pressão-pressão utiliza exclusivamente os dados de pressão adquiridos em diferentes posições do reservatório. O modelo considerado consiste em dois poços, um injetor, localizado na zona interna do reservatório, e um observador, na zona externa. A validação da solução proposta foi realizada por meio da comparação dos resultados analíticos com aqueles obtidos em um simulador comercial baseado em diferenças finitas. / [en] The injectivity test is a conventional technique in reservoir engineering used for oil recovery and formation evaluation. Typically, water is injected to displace the existing oil by increasing the pressure in the pores. In this test, the pressure response measurement provides valuable information about the reservoir parameters, including permeability data. Therefore, researchers aim to develop mathematical equations that could accurately model pressure response during these tests for reservoir management and maintenance prediction purposes. This work introduces a new analytical solution for injectivity test analysis. The solution combines the pressure-pressure convolution technique with a two-zone radial model. It allows the evaluation of the injectivity test without precise flow rate data, as the pressure-pressure convolution exclusively uses the pressure data acquired at different positions in the reservoir. The reservoir model comprises an injector well in the inner zone of the reservoir and an observation well in the outer zone for measuring pressure response. The proposed solution was validated by comparing the analytical results with those obtained from a finite differences-based commercial simulator.