The master thesis deals with the reconstruction of the sewerage in Brno-city, between the streets Roosveltova and Solniční. Due to the location of sewer in build-up area, the reconstruction will be performed by tunnelling technology – shield excavation. The thesis is mainly dedicate with design and structual design of sewer lining. The mathematical model is created in software Plaxis 8.2 2D.

No description available.

No Abstract Provided / Thesis / Candidate in Philosophy

Significant stray magnetic field exists around the coils when charging the electric vehicles (EVs) with inductive power transfer (IPT), owning to the large air gap between the transmitter and receiver. The methods for field attenuation usually introduce extra losses and reduce the efficiency. This study focuses on the synergetic attenuation of stray magnetic field which is optimized simultaneously with the efficiency. The optimization is realized with Pareto front. In this dissertation, three methods are discussed for the field attenuation. The first method is to tune the physical parameters of the winding, such as the inner radii, outer radii, distribution of the turns, and types of the litz wires. The second method is to add metal shields around the IPT coils, in which litz wires are used as shields to reduce the shielding losses. The third method is to control the phases of winding currents, which avoids increasing the size and weight of the IPT coils. To attenuate the stray magnetic field by tuning the physical parameters, the conventional method is to sweep all the physical parameters in finite-element simulation. This takes thousands of simulations to derive the Pareto front, and it's especially time-consuming for three-dimensional simulations. This dissertation demonstrates a faster method to derive the Pareto front. The windings are replaced by the lumped loops. As long as the number of turns for each loop is known, the efficiency and magnetic field are calculated directly from the permeance matrices and current-to-field matrices. The sweep of physical parameters in finite-element simulation is replaced by the sweep of the turns numbers for the lumped loops in calculation. Only tens of simulations are required in the entire procedure, which are used to derive the matrices. An exemplary set of coils was built and tested. The efficiency from the matrix calculation is the same as the experimental measurement. The difference for stray magnetic field is less than 12.5%. Metal shields attenuate the stray magnetic field effectively, but generates significant losses owning to the uneven distribution of shield currents. This dissertation uses litz wires to replace the conventional plate shield or ring shield. Skin effect is eliminated so the shield currents are uniformly distributed and the losses are reduced. The litz shields are categorized to two types: shorted litz shield and driven litz shield. Circuit models are derived to analyze their behaviors. The concept of lumped-loop model is applied to derive the Pareto front of efficiency versus stray magnetic field for the coils with litz shield. In an exemplary IPT system, coils without metal shield and with metal shields are optimized for the same efficiency. Both the simulation and experimental measurement verify that the shorted litz shield has the best performance. The stray magnetic field is attenuated by 65% compared to the coils without shield. This dissertation also introduces the method to attenuate the stray magnetic field by controlling the phases of winding currents. The magnetic field around the coils is decomposed to the component in the axial direction and the component in the radial direction. The axial component decreases with smaller phase difference between windings' currents, while the radial component exhibits the opposite property. Because the axial component is dominant around the IPT coils, decreasing the phase difference is preferred. The dual-side-controlled converter is applied for the circuit realization. Bridges with active switches are used for both the inverter on the transmitter side and the rectifier on the receiver side. The effectiveness of this method was verified both in simulation and experiment. Compared to the conventional series-series IPT with 90° phase difference between winding currents, stray magnetic field was attenuated by up to 30% and 40% when the phase differences of winding currents are 50° and 40°, respectively. Furthermore, an analytical method is investigated to calculate the proximity-effect resistance of the planar coils with ferrite plate. The objective of this method is to work together with the fast optimization which uses the lumped-loop model. The existence of the ferrite plate complicates the calculation of the magnetic field across each turn which is critical to derive the proximity-effect resistance. In this dissertation, the ferrite plate is replaced by the mirrored turns according to the method of image. The magnetic fields are then obtained from Ampere's Law and Biot-Savart Law. Up to 200 kHz, the difference of the proximity-effect resistance is less than 15% between calculation and measurement. / Ph. D. / Inductive power transfer for the battery charging of electric vehicles uses loosely coupled coils to replace the cables and plugs. The power is transferred from transmitter to receiver across tens of centimeters. Significant stray magnetic field exists around the coils owning to the large gap, which should be attenuated for the safety consideration of human beings. Three methods are discussed for the field attenuation. The first method is to tune the physical parameters of the winding, such as the inner radii, outer radii, distribution of the turns, and types of the litz wires. The second method is to add metal shields around the IPT coils, in which litz wires are used as shields to reduce the shielding losses. The third method is to control the phases of winding currents, which avoids the increase of the size and weight of the IPT coils. However, the field attenuation usually comes with reduced efficiency of the system. The work in this dissertation is focused on the synergetic attenuation of stray magnetic field in inductive power transfer for electric vehicles. The optimization is realized with Pareto front. The coils are optimized for low stray magnetic field and high efficiency simultaneously.

The work of this master thesis is based on analyses of monthly precipitation data from 70 stations of the SMHI (Swedish Meteorological and Hydrological Institute) in Sweden, in the period 1860-2014, using the information for the year of introduction of the wind shield at each station. The primary goal is the calculation of correction factors which will be applied on the precipitation data in the period of measurements before the introduction of the wind shield. This correction will counterbalance the underestimation of the collected precipitation by the unshielded precipitation gauges due to the effect of the wind. The wind induced error, related to aerodynamical effects, increases with increasing wind speed. The stronger the wind, the more capable it is of deflecting the precipitation water droplets or snowflakes, falling towards the gauge orifice, away from it. In spite of the important efficiency of the wind shield which acts to diminish the wind error, the long-term effect of changing the measuring instrumentation at some time in the observations history is the production of inhomogeneous data in the measurements records. Inhomogeneous precipitation data are sources of errors in climatology and hydrology and result in misleading conclusions regarding the climate change and climate variations, hence they should be identified and corrected through a homogenization method. The analysis includes the comparison of the precipitation data of each station during two periods, one before and one after the introduction of the wind shield. This comparison leads to the calculation of ratios representing the increase in the catch between the two periods due to the introduction of the wind shield. Temperature data are also processed in order to estimate the type of precipitation (snow/rain) in each case. The monthly corrections ranged between 5 %, for rain, and 27 % for snow precipitation. The absolute value of the increase of the average annual precipitation due the implementation of the correction was 50 mm. The comparison of the corrected against the uncorrected precipitation time series indicated a less pronounced increase (0.74 mm/y) of the precipitation during the last 150 years, after the application of the correction, compared to the increase indicated from the uncorrected data (1.19 mm/y). / Kontinuerliga samt felfria nederbördsmätningar är av stor betydelse för geovetenskaper som klimatologi och hydrologi därför att nederbördsdata är en av de primära meteorologiska parametrarna för forskning om klimatförändringen. Att säkerställa felfria (homogena) nederbörds tidsserier betyder i stort sett att säkerställa homogenitet genom att identifiera och korrigera inhomogena data. Icke homogena data uppkommer på grund av förändringar i mätmetoder och mätförhållanden under observationstiden, sedan 1860-talet tills idag alltså. Denna studies syfte är att beräkna en korrektion som ska användas för att korrigera nederbördsmätningar som utfördes sedan 1860 utan vinskydd. Vindskyddet eller vindskärmen, en speciell utrustning som användas på nederbördsinsamlare, infördes gradvis under perioden 1900-1960 vid de svenska nederbördstationerna. Vindskyddet introducerades med avsikt att minska vindens påverka vid nederbördsinsamling. Men trotts den positiva effekten som vindskyddet ledde till, genom den ökade nederbördsmängden som samlades in, skapade denna förändring av mätarutrustningen inhomogena data. Bearbetningen skedde för månadsnederbördsdata från 70 stationer från SMHIs meteorologiska nätverk genom att jämföra nederbördsobservationer som genomfördes under perioderna tio år före och tio år efter införandet av vindskydd. Dessutom användes temperaturdata från samma stationer för att uppskatta nederbördslag (snö/regn). Skälet till detta är att vinskyddseffekten är olika mellan snö och regn. Beräkningarna och bestämningen av nederbördslag ledde till en 5 % respektive 27 % nederbörds ökning för regn och snö för de mätningarna som utfördes utan vindskydd. I genomsnitt har de korrigerade värdena, under perioden som vinskyddet saknades, ökat med omkring 50 mm.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: A reactor cavity cooling system (RCCS) is used in the PBMR to protect the concrete citadel surrounding the reactor from direct nuclear radiation impingement and heat. The speci ed maximum operating temperature of the concrete structure is 65 ±C for normal operating conditions and 125 ±C for emergency shut-down conditions. A conceptual design of an entirely passive RCCS suitable for the PBMR was done by using closed loop thermosyphon heat pipes (CLTHPs) to remove heat from a radiation heat shield over a horizontal distance to an annular cooling dam placed around the PBMR. The radiation shield is placed in the air space between the Reactor Pressure Vessel (RPV) and the concrete citadel, 180 mm from the concrete citadel. A theoretical heat transfer model of the RCCS was created. The theoretical model was used to develop a computer program to simulate the transient RCCS response during normal reactor operation, when the RCCS must remove the excess generated heat from the reactor cavity and during emergency shut-down conditions, when the RCCS must remove the decay heat from the reactor cavity. The main purpose of the theoretical model is to predict the surface temperature of the concrete citadel for di erent heat generation modes in the reactor core and ambient conditions. The theoretical model assumes a 1D geometry of the RCCS. Heat transfer by both radiation and convection from the RPV to the radiation heat shield (HS) is calculated. The heat shield is modelled as a n. The n e ciency was determined with the experimental work. Conduction through the n is considered in the horizontal direction only. The concrete structure surface is heated by radiation from the outer surface of the heat shield as well as by convection heat transfer from the air between the heat shield and the concrete structure surface. The modelling of the natural convection closed loop thermosyphon heat pipes in the RCCS is done by using the Boussinesq approximation and the homogeneous ow model. An experiment was built to verify the theoretical model. The experiment is a full scale model of the PBMR in the horizontal, or main heat transfer, direction, but is only a 2 m high section. The experiments showed that the convection heat transfer between the RPV and the HS cannot be modelled with simple natural convection theory. A Nusselt number correlation developed especially for natural convection in enclosed rectangles found in literature was used to model the convection heat transfer. The Nusselt number was approximately 3 times higher than that which classic convection theory suggested. An optimisation procedure was developed where 121 di erent combinations of n sizes and heat pipe sizes could be used to construct a RCCS once a cooling dam size was chosen. The purpose of the optimisation was to nd the RCCS with the lowest total mass. A cooling dam with a diameter of 50 m was chosen. The optimal RCCS radiation heat shield that operates with the working uid only in single phase has 243 closed loop thermosyphon heat pipes constructed from 62.72 mm ID pipes and 25 mm wide atbar ns. The total mass of the single phase RCCS is 225 tons. The maximum concrete structure temperature is 62.5 ±C under normal operating conditions, 65.8 ±C during a PLOFC emergency shut-down condition and 80.9 ±C during a DLOFC emergency shut-down condition. In the case where one CLTHP fails and the adjacent two must compensate for the loss of cooling capacity, the maximum concrete structure temperature for a DLOFC emergency shut-down will be 87.4 ±C. This is 37.6 ±C below the speci ed maximum temperature of 125 ±C. The RCCS design is further improved when boiling of the working uid is induced in the CLTHP. The optimal RCCS radiation heat shield that operates with the working uid in a liquid-vapour mixture, or two phase ow, has 338 closed loop thermosyphon heat pipes constructed from 38.1 mm ID pipes and 20 mm wide atbar ns. The total mass of the two phase RCCS is 198 tons, 27 tons less than the single phase RCCS. The maximum concrete structure temperature is 60 ±C under normal operating conditions, 2.5 ±C below that of the single phase RCCS. During a PLOFC emergency shut-down condition, the maximum concrete structure temperature is 62.3 ±C, 3.5 ±C below that of the single phase RCCS and still below the normal operating temperature of the single phase RCCS. By inducing two phase ow in the CLTHP, the maximum temperature of the working uid is xed equal to the saturation temperature of the working uid at the vacuum pressure. This property of water is used to limit the concrete structure temperature. This e ect is seen in the transient response of the RCCS where the concrete structure temperature increases until boiling of the working uid starts and then the concrete structure temperature becomes constant irrespective of the heat load on the RCCS. An increased heat load increases the quality of the working uid liquid-vapour mixture. Working uid qualities approaching unity causes numerical instabilities in the theoretical model. The theoretical model cannot capture the heat transfer to a control volume with a density lower than approximately 20 kg/m3. This limits the extent to which the two phase RCCS can be optimised. Recommendations are made relating to future work on how to improve the theoretical model in particular the convection modelling in the reactor cavities as well as the two phase ow of the working uid. Further recommendations are made on how to improve the basic design of the heat shield as well as the cooling section of the CLTHPs. / AFRIKAANSE OPSOMMING: 'n Reaktor lug spasie verkoelingstelsel (RLSVS) word in die PBMR gebruik om die beton wat die reaktor omring te beskerm teen direkte stralingskade en hitte. Die gespesi seerde maksimum temperatuur van die beton is 65 ±C onder normale bedryfstoestande en 125 ±C gedurende die noodtoestand afskakeling van die reaktor. 'n Konseptuele ontwerp van 'n geheel en al passiewe RLSVS geskik vir die PBMR is gedoen deur gebruik te maak van geslote lus termo-sifon (GLTSe) om hitte van die stralingskerm te verwyder oor a horisontale afstand na 'n ringvormige verkoelingsdam wat rondom die reaktor geposisioneer is. Die stralingskerm word in die lug spasie tussen die reaktor drukvat (RDV) en die beton geplaas, 180 mm vanaf die beton. 'n Teoretiese hitteoordrag model van die RLSVS was geskep. Die teoretiese model was gebruik vir die ontwikkeling van 'n rekenaar program wat die transiënte gedrag van die RLSVS sal simuleer gedurende normale bedryfstoestande, waar die oorskot gegenereerde hitte verwyder moet word vanuit die reaktor lug spasie, asook gedurende noodtoestand afskakeling van die reaktor, waar die afnemingshitte verwyder moet word. Die primêre doel van die teoretiese model is om the oppervlak temperatuur van die beton te voorspel onder verskillende bedryfstoestande asook verskillende omgewingstoestande. Die teoretiese model aanvaar 'n 1D geometrie van die RLSVS. Hitte oordrag d.m.v. straling asook konveksie vanaf die RDV na die stralingskerm word bereken. The stralingskerm word gemodelleer as 'n vin. Die vin doeltre endheid was bepaal met die eksperimente wat gedoen was. Hitte geleiding in die vin was slegs bereken in die horisontale rigting. Die beton word verhit deur straling vanaf die agterkant van die stralingskerm asook deur konveksie vanaf die lug tussen die stralingskerm en die beton. The modellering van die natuurlike konveksie GLTS hitte pype word gedoen deur om gebruik te maak van die Boussinesq benadering en die homogene vloei model. 'n Eksperiment was vervaardig om the teoretiese model te veri eer. Die eksperiment is 'n volskaal model van die PBMR in die horisontale, of hoof hitteoordrag, rigting, maar is net 'n 2 m hoë snit. Die eksperimente het gewys dat die konveksie hitte oordrag tussen die RDV en die stralingskerm nie met gewone konveksie teorie gemodelleer kan word nie. 'n Nusselt getal uitdrukking wat spesi ek ontwikkel is vir natuurlike konveksie in geslote, reghoekige luggapings wat in die literatuur gevind was, was gebruik om die konveksie hitteoordrag te modelleer. Die Nusselt getal was ongeveer 3 maal groter as wat klassieke konveksie teorie voorspel het. 'n Optimeringsprosedure was ontwikkel waar 121 verskillende kombinasies van vin breedtes en pyp groottes wat gebruik kan word om 'n RLSVS te vervaardig nadat 'n toepaslike verkoelingsdam diameter gekies is. Die doel van die optimering was om die RLSVS te ontwerp wat die laagste totale massa het. 'n Verkoelingsdam diameter van 50 m was gekies. Die optimale RLSVS stralingskerm, waarvan die vloeier slegs in die vloeistof fase bly, bestaan uit 243 GLTSe wat van 62.72 mm binne diameter pype vervaardig is met 25 mm breë vinne. The totale massa van die enkel fase RLSVS is 225 ton. Die maksimum beton temperatuur is 62.5 ±C vir normale bedryfstoestande, 65.8 ±C vir 'n PLOFC noodtoestand afskakeling en is 80.9 ±C vir 'n DLOFC noodtoestand afskakeling. In die geval waar een GLTS faal gedurende 'n DLOFC noodtoestand afskakeling en die twee naasgeleë GLTSe moet kompenseer vir die vermindering in verkoelings kapasiteit, is die maksimum beton temperatuur 87.4 ±C. Dit is 37.6 ±C laer as die gespesi seerde maksimum temperatuur van 125 ±C. Die RLSVS ontwerp kan verder verbeter word wanneer die vloeier in die GLTSe kook. Die optimale RLSVS stralingskerm met die vloeier wat kook, of in twee fase vloei is, bestaan uit 338 GLTSe wat van 38.1 mm binne diameter pype vervaardig is met 20 mm breë vinne. The totale massa van die twee fase vloei RLSVS is 198 ton, 27 ton ligter as die enkel fase RLSVS. Die maksimum beton temperatuur is 60 ±C vir normale bedryfstoestande, 2.5 ±C laer as die enkel fase RLSVS. Gedurende 'n PLOFC noodtoestand afskakeling is die maksimum beton temperatuur 62.3 ±C, 3.5 ±C laer as die enkel fase RLSVS en nogtans onder die maksimum beton temperatuur van die enkel fase RLSVS vir normale bedryfstoestande. Deur om koking te veroorsaak in die GLTS word die maksimum temperatuur van die vloeier vasgepen gelyk aan die versadigings temperatuur van die vloeier by die vakuüm druk. Hierdie einskap van water word gebruik om 'n limiet te sit op die maksimum temperatuur van die beton. Hierdie e ek kan gesien word in die transiënte gedrag van die RLSVS waar die beton temperatuur styg tot en met koking plaasvind en dan konstant raak ongeag van die hitte belasting op die RLSVS. 'n Toename in die hitte belasting veroorsaak net 'n toename in die kwaliteit van die vloeistof-gas mengsel. Mengsel kwaliteite van 1 nader veroorsaak numeriese onstabiliteite in die teoretiese model. The teoretiese model kan nie die hitteoordrag beskryf na 'n kontrole volume wat 'n digtheid het laer as ongeveer 20 kg/m3. Hierdie plaas 'n limiet op die optimering van die twee fase RLSVS. Aanbevelings was gemaak met betrekking tot toekomstige werk aangaande die verbetering van die teoretiese model met spesi eke klem op die modellering van konveksie in die reaktor asook die modellering van twee fase vloei. Verdere aanbevelings was gemaak aangaande die verbetering van die stralingskerm ontwerp asook die ontwerp van die verkoeling van die GLTSe.

In this paper the effect of capital structure on profitability has been investigated among Swedish companies. The essay intends to examine how the relationship between debt and profitability appear among Swedish companies and if the relationship differs between industries. The purpose is to find out how debt affects the profitability of Swedish companies. A quantitative approach has been applied. The selection was made among companies listed on Nasdaq OMX Stockholm, which resulted in a sample of 207 companies. Several regression analyzes has been formed, based on the independent variable debt-ratio and the dependent variables profit margin, pre-tax profit margin, operating margin, return on assets and return on equity. The variables were calculated using data from each company’s annual reports for the entire investigation period, year 2009-2013. The theories in the study are the capital structure irrelevance theory, trade-off, agency theory and the pecking-order theory. The scientific papers which has served as reference for this paper is a study made by Addae et al., where the relationship between debt and profitability were examined among listed companies in Ghana and a study made by Panno, where a similar relationship were examined among companies in the UK and Italy. The results indicates positive relationships between debt-ratio and profit margin, pre-tax profit margin and operating margin. This result is in parity with that from Pannos investigation and it seems that Swedish companies tend to take advantage of the tax-shield, giving support for the trade-off theory. However, regarding the relationship between debt-ratio and return on assets as well as equity, no significant relationship could be found. This means that it is not possible to say that more debt causes changes in return on assets or return on equity among Swedish companies. Furthermore, regarding the relationships between industries, it has only been possible to find significant relationships in 2 out of 17 industries and therefore no valid conclusions could be drawn concerning that question. / I denna uppsats har kapitalstrukturens effekt på lönsamhet undersökts bland svenska företag. Uppsatsen ämnar besvara hur sambandet mellan skuldsättning och lönsamhet ser ut bland svenska företag och om sambandet skiljer sig mellan olika branscher. Syftet är att ta reda på hur skuldsättningen påverkar lönsamheten i svenska företag. För att uppfylla syftet har en kvantitativ forskningsansats tillämpats. Urvalet har gjorts utifrån noterade företag på Nasdaq OMX Stockholm som uppfyllt tre villkor, vilket har resulterat i ett urval om 207 stycken företag. För att besvara frågeställningen har det genomförts regressionsanalyser som baserats på den oberoende variabeln skuldandel och de beroende variablerna vinst-, bruttovinst- och rörelsemarginal samt räntabilitet på eget och totalt kapital. Beräkningen av variablerna har föregåtts av en omfattande datainsamling där grunddata hämtats in från de aktuella företagens årsredovisningar för hela undersökningsperioden, åren 2009-2013. De centrala vetenskapliga teorierna som behandlats i undersökningen är kapitalstrukturens irrelevansteori, trade-off, agentteorin och pecking-order. De vetenskapliga artiklar som fungerat som referensram för uppsatsen är en studie av Addae m.fl., där sambandet mellan skuldsättning och lönsamhet har undersökts bland noterade företag i Ghana och en studie av Panno, där ett liknande samband undersökts bland företag i Storbritannien och Italien. Resultaten pekar på positiva samband mellan skuldandel och vinst-, bruttovinst- och rörelsemarginal. Detta ligger i linje med de resultat som Panno funnit och talar för att svenska företags kapitalstruktur förklaras av trade-off teorin, som utgår ifrån irrelevansteorins skattesköld i förhållande till konkurskostnader. Vad gäller sambandet mellan skuldandel och räntabilitet på eget och totalt kapital har inget signifikant samband kunnat styrkas. Det innebär att det inte går att säga att en högre skuldsättning bland svenska företag leder till en förändring i varken avkastning på eget eller totalt kapital. Vidare gäller att på branschnivå har det bara gått att finna signifikanta samband mellan skuldsättning och lönsamhet i 2 av 17 branscher.

Inledning: Modigliani och Miller-teoremet betraktas som en milstolpe och ett paradigmskifte inom Corporate Finance. Forskningen bakom teoremet har gett upphov till den kontroversiella slutsatsen att ett företags kapitalstruktur är irrelevant på en jämviktsmarknad, utan beskattning. När beskattning däremot förekommer, ökar företagsvärdet motsvarande den avdragsgilla skatten på räntekostnader vid belåning. Teoremet har dock inte varit utan kritik. Flera forskare har undersökt teoremet och kritiserat teoremets antaganden. Syfte: Syftet med studien är att undersöka Modigliani och Miller-teoremet i avseende av kapitalstrukturens inverkan på företags aktiekurser. Tidigare forskning: Modigliani och Miller-teoremet med dess antaganden presenteras inledningsvis som studiens grundläggande teori. Därefter presenteras agentteorin, signaleringsteorin, trade-off-teori och effektiva marknadshypotesen tillsammans med tidigare forskningsstudier om teoremet och antagandena. Metod: Studien tillämpar en kvantitativ metod, med tre regressionsmodeller. Det slumpmässiga urvalet består av tio företag inom industribranschen som är registrerade på Stockholmsbörsen. Urvalet består av paneldata från företagen under perioden 2005 till 2012. Studiens empiri består av historiska aktiekurser och årsredovisningar. Resultat: Skuldsättningsgraden visar en låg och icke signifikant korrelation med aktiekurserna för de undersökta företagen, i samtliga tre regressionsmodeller. Skatteskölden visar en högre och signifikant korrelation med aktiekursen, medan kontrollvariabeln vinst per aktie EPS visar den högsta korrelationen med aktiekursen, som responsvariabel. Slutsats: Studiens resultat visar inget empiriskt stöd för Modigliani och Miller-teoremet i dess helhet. Förklaringen till resultaten kan vara att antagandena inte tillfredsställs inom empirin. Agentteori, signaleringsteori, trade-off-teori och effektiva marknadshypotesen kan stå som förklaringar till studiens resultat. / Introduction: Modigliani and Miller theorem is regarded as a milestone and a paradigm shift in Corporate Finance. The research behind the theorem has given rise to the controversial conclusion that a company's capital structure is irrelevant in an equilibrium market, without taxation. In contrast, when taxation occurs firm value will increase equivalent to the deductible tax on interest expense when debt is issued. The theorem has not been without criticism. Several researchers have examined the theorem and criticised its assumptions. Purpose: The purpose of the study is to investigate the Modigliani and Miller theorem in respect of capital structure’s impact on companies' share prices. Literature Review: The Modigliani and Miller theorem with its assumptions is initially presented as the study’s main theorem. The presentation of the theorem is followed by a description of agency theory, signalling theory, trade-off theory and the efficient market hypothesis, along with previous studies on the theorem and its assumptions. Research Methodology: The study applies a quantitative approach, with three regression models. The random sample consists of ten companies in the industrial sector, that are listed on the Stockholm Stock Exchange. The sample is based on panel data of the companies during the period 2005 to 2012. The study's empirical data consists of historical stock prices and annual reports. Empirical Results: The leverage ratio, i.e. debt to equity ratio, indicates a low and non-signif-icant correlation with the stock prices of the examined companies, in all three regression models. The tax shield indicates a higher and significant correlation with the stock price, while the control variable earnings per share EPS indicates the highest correlation with the stock prices, as the response variable. Conclusions: The study’s results show no empirical support for the Modigliani-Miller theorem in its entirety. The explanation for the findings may be that the assumptions are not satisfied in the empirical data. Agency theory, signalling theory, trade-off theory and the efficient market hypothesis may serve as explanations of the study’s results.

Efeitos térmicos em teorias de calibre em (2+1) dimensões são estudados em espaços onde as coordenadas podem ou não comutar. No caso comutativo, a dependência com a temperatura do tensor de polarização é calculada a um laço em teorias envolvendo tanto bósons quanto férmions. Como aplicação, são calculados os processos de blindagem em tais modelos, chegando ao interessante resultado de que cargas magnéticas não sofrem tais efeitos na QED3. Uma prova válida em qualquer ordem de perturbação é desenvolvida, confirmando este comportamento. Em teorias não comutativas, são estudadas as correções a um laço ao coeficiente de Chern-Simons, sendo encontrado que não existe o fenômeno da mistura UV/IR na teoria Chern-Simons-Higgs. O comportamento assintótico de tal coeficiente é analisado no regime de altas temperaturas. Vários outros aspectos envolvendo os efeitos térmicos em teorias de Chern-Simons são explorados. / Thermal effects in (2+1)-dimensional gauge theories are studied in both commutative as well as noncommutative manifolds. In the first situation, the finite temperature polarization tensor is computed a tone loop for fermionic and bosonic couplings. As an application, the screening masses are evaluated and it is found the surprising result that magnetic charges are not screened in QED3. It is demonstrated that this result holds to any order in pertubationtheory. In the noncommutative case, the one loop correction to the Chern-Simons coefficient is studied, and it is found that there is no UV/IR mixing in the Chern-Simons-Higgs model. The asymptotic behavior of such coefficient is analised in the high temperature regime. Several other interesting aspects involving thermal effects of Chern-Simons theories are also discussed.

Esta pesquisa teórica investiga o desenvolvimento da noção de couraça nos primeiros quinze anos da obra de Wilhelm Reich, de 1920 até 1935. Como objetivo central, buscamos responder a seguinte questão norteadora: qual(ais) o(s) sentido(s) de couraça no pensamento de Wilhelm Reich? Visamos, sobretudo, contribuir para o esclarecimento e a discussão dessa importante noção do pensamento reichiano. Em termos de método, a fim de acompanhar o percurso do pensamento do autor, abordamos a obra de acordo com sequência cronológica de publicação. Com essa orientação histórica, elencamos e analisamos textos que, a nosso ver, fornecem subsídios para a compreensão da noção em tela. Além disso, ficamos atentos a prováveis sinônimos e sentidos utilizados, mesmo que o termo propriamente dito não estivesse explicitamente citado. Como preparação do terreno, realizamos uma pesquisa etimológica sobre o termo couraça. Em seguida, elencamos dois autores - o filósofo francês Henri Bergson e o fundador da psicanálise Sigmund Freud - investigados devido à importância dos mesmos na construção do pensamento reichiano como um todo e, possivelmente também, em relação à noção de couraça. Em termos de resultados, os escritos de Reich analisados indicaram que as significações de couraça como defesa, proteção e resistência estão sempre presentes. Dentre os artigos acessados, localizamos a primeira aparição do vocábulo em 1922, como couraça narcísica. Constatamos que, para Reich, a couraça mantém contato com as realidades interna e externa, articula as noções de economia pulsional, ego e caráter, além de estar relacionada à operação do recalque. A princípio, é concebida na esfera psíquica, mas, gradativamente, passa a ser considerada, também, no âmbito somático, principalmente como hipertonia muscular crônica. Ainda, tecemos algumas relações com a visão de Bergson sobre o assunto e com a conceituação freudiana acerca do escudo protetor. Por fim, na esfera do tema saúde-doença, registramos algumas ponderações a respeito da relação entre a noção de couraça e o processo do desenvolvimento humano / This research examines the development of the notion of armor in the first fifteen years of Wilhelm Reich´s work, from 1920 until 1935. As the main goal, we aimed to answer the question: What is (are) the meaning(s) of the term armor in Wilhelm Reich´s thought? We had in view, above all, contribute to clear up and discuss this important notion in Reichian thought. In terms of method, in order to keep track of the author´s thinking route, we followed the chronological sequence of his publications. Based on this historical orientation, we focused and detailed the texts that, in our view, supplies subsidies for the comprehension about the notion of armor. Moreover, we drew our attention to the probable synonyms and meanings, even if the term was not cited. To begin, we researched the etymology of the term. Then, we listed two authors the French philosopher Henri Bergson and the founder of psychoanalysis Sigmund Freud investigated because of their importance on the construction of early Reich´s thought and, possibly, concerning the notion of armor. In terms of results, the analyzed Reich´s texts indicated that the significances of defense, protection and resistance are always present. Among the accessed articles, we localized the very first appearance of the word in 1922, as narcissistic armor. We verified that, to Reich, the armor keeps in contact with the inner e outer realities, articulates the notions of drive economy, ego and character, and has relations with the repression operation. In the beginning, it is conceived in the psychological sphere, but, gradually, it is considered in a somatic scope as well, especially as a chronic muscular hypertony. Yet, we wove some relations with Bergson´s view about the theme and with the freudians conception concerning the protective shield. Finally, under the health-disease angle, we pointed out some aspects and relations between the notion of armor and the human development process