[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] 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.

[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.

Mixed-Criticality Systems (MCSs) include tasks with multiple levels of criticality and different modes of operation. These systems bring benefits such as energy and resource saving while ensuring safe operation. However, management of available resources in order to achieve high utilization, low power consumption, and required reliability level is challenging in MCSs. In many cases, there is a trade-off between these goals. For instance, although using fault-tolerance techniques, such as replication, leads to improving the timing reliability, it increases power consumption and can threaten life-time reliability. In this work, we introduce an approach named Life−timePeakPower management inMixed−Criticalitysystems (LPP-MC) to guarantee reliability, along with peak power reduction. This approach maps the tasks using a novel metric called Reliability-Power Metric (RPM). The LPP-MC approach uses this metric to balance the power consumption of different processor cores and to improve the life-time of a chip. Moreover, to guarantee the timing reliability of MCSs, a fault-tolerance technique, called task re-execution, is utilized in this approach. We evaluate the proposed approach by a real avionics task set, and various synthetic task sets. The experimental results show that the proposed approach mitigates the aging rate and reduces peak power by up to 20.6% and 17.6%, respectively, compared to state-of-the-art.

No description available.

Trafikverket operates about 12000 Switches and crossings (SnCs) of which 6800 are equipped with an electrical heating system of 10−30kW power to keep SnCs functional throughout the winters by keeping them free of Snow/Ice. The energy consumption is approximately 200−130GWh/year costing approximately 10−15 million Euros annually. Electricity demand is continuously rising in Sweden and if coupled with unpredictable events can highly impact the grid energy mix and electricity prices which can lead to a higher operating carbon footprint & expenses. This master thesis work is developed through a couple of research programs to investigate the power usage in wayside objects. Currently, work is in progress to make the wayside objects ‘smart’ so that they can operate fully autonomously with two objectives to reduce the overall power consumption and obtain it from local energy resources. Mathematical modeling of unsteady close contact melting of rectangular Ice/Snow blocks of different volumes on the horizontal surfaces has been solved using numerical methods to calculate the melting time and power requirement. A parametric study has been done for various sizes, and initial & hot surface temperatures. Further, using ANSYS Fluent, CFD simulations have been performed to calculate the heat transfer rate from the Rail body for various combinations of heat source & ambient temperature, and wind speeds. These results shall help to devise a control strategy for the dynamic power supply which can help to optimize the power consumption. Finally, evaluating the renewable resources potential; ground source heat pumps using borehole U-pipes appear to be the best option which can drastically reduce the electricity requirement for the optimized heating power requirement. Most of Sweden has granite bedrock which is one of the reasons for the successful deployment of heat pumps. It’s definitely worth expanding its usage in other sectors as well like Railways. / Trafikverket driver cirka 12 000 spårväxlar och spårkorsningar varav 6 800 är utrustade med ett elektriskt värmesystem på 10 - 30kW effekt för att hålla växlar och korsningar funktionella under hela vintrarna genom att hålla dem fria från snö/is. Energiförbrukningen är cirka 200-130 GW h/år och kostar cirka 10-15 miljoner euro per år. Efterfrågan på el ökar kontinuerligt i Sverige och kan i kombination med oförutsägbara händelser i hög grad påverka nätets energimix och elpris vilket i sin tur kan leda till ett högre koldioxidavtryck och högre driftskostnader. Detta examensarbete utvecklades genom ett par forskningsprogram med fokus på strömförbrukningen i järnvägssystemet. Just nu pågår ett arbete med att göra järnvägssystemet "smart" så att det kan fungera helt automatiskt med två mål: att minska den totala energiförbrukningen och få den från lokala energiresurser. Kontaktsmältning av rektangulärt is/snö-block av olika volymer på horisontella ytor har lösts med hjälp av numeriska metoder för att beräkna smälttid och effektbehov. En parametrisk studie har gjorts för olika storlekar och initiala och varma yttemperaturer. Vidare, med hjälp av ANSYS Fluent, har CFD-simuleringar utförts för att beräkna värmeöverföringshastighet från järnvägsspåret för olika kombinationer av värmekälla och omgivning temperatur och vindhastigheter. Dessa resultat ska bidra till att utforma en styrstrategi för den dynamiska strömförsörjningen som kan bidra till att optimera strömförbrukningen. Slutligen, för att utvärdera potentialen för förnybara resurser, verkar bergvärmepumpar som använder borrhåls U-rör vara det bästa alternativet som drastiskt kan minska elbehovet för det optimerade värmeeffektbehovet. Större delen av Sverige har berggrund av granit vilket är en av anledningarna till den framgångsrika utbyggnaden av värmepumpar. Det är definitivt värt att utöka användningen i andra sektorer också som järnvägar.

New decline curve models have been developed to overcome the boundary-dominated flow assumption of the basic Arps’ models, which restricts their application in ultra-low permeability reservoirs exhibiting long-duration transient flow regimes. However, these new decline curve analysis (DCA) methods are still based only on production rate data, relying on the assumption of stable flowing pressure. Since this stabilized state is not reached rapidly in most cases, the applicability of these methods and the reliability of their solutions may be compromised. In addition, production performance predictions cannot be disassociated from the existing operation constraints under which production history was developed. On the other hand, DCA is often carried out without a proper identification of flow regimes. The arbitrary application of DCA models regardless of existing flow regimes may produce unrealistic production forecasts, because these models have been designed assuming specific flow regimes. The main purpose of this study was to evaluate the possible benefits provided by including flowing pressures in production decline analysis. As a result, it have been demonstrated that decline curve analysis based on pressure-normalized rates can be used as a reliable production forecasting technique suited to interpret unconventional wells in specific situations such as unstable operating conditions, limited availability of production data (short production history) and high-pressure, rate-restricted wells. In addition, pressure-normalized DCA techniques proved to have the special ability of dissociating the estimation of future production performance from the existing operation constraints under which production history was developed. On the other hand, it was also observed than more consistent and representative flow regime interpretations may be obtained as diagnostic plots are improved by including MBT, pseudovariables (for gas wells) and pressure-normalized rates. This means that misinterpretations may occur if diagnostic plots are not applied correctly. In general, an improved forecasting ability implies greater accuracy in the production performance forecasts and more reliable reserve estimations. The petroleum industry may become more confident in reserves estimates, which are the basis for the design of development plans, investment decisions, and valuation of companies’ assets.