Wetting and phase transitions play a very important role our daily life. Molecularly thin films of long-chain alkanes at solid/vapour interfaces (e.g. C30H62 on silicon wafers) are very good model systems for studying the relation between wetting behaviour and (bulk) phase transitions. Immediately above the bulk melting temperature the alkanes wet partially the surface (drops). In this temperature range the substrate surface is covered with a molecularly thin ordered, solid-like alkane film ("surface freezing"). Thus, the alkane melt wets its own solid only partially which is a quite rare phenomenon in nature. The thesis treats about how the alkane melt wets its own solid surface above and below the bulk melting temperature and about the corresponding melting and solidification processes.<br> Liquid alkane drops can be undercooled to few degrees below the bulk melting temperature without immediate solidification. This undercooling behaviour is quite frequent and theoretical quite well understood. In some cases, slightly undercooled drops start to build two-dimensional solid terraces without bulk solidification. The terraces grow radially from the liquid drops on the substrate surface. They consist of few molecular layers with the thickness multiple of all-trans length of the molecule. By analyzing the terrace growth process one can find that, both below and above the melting point, the entire substrate surface is covered with a thin film of mobile alkane molecules. The presence of this film explains how the solid terrace growth is feeded: the alkane molecules flow through it from the undercooled drops to the periphery of the terrace.<br> The study shows for the first time the coexistence of a molecularly thin film ("precursor") with partially wetting bulk phase. The formation and growth of the terraces is observed only in a small temperature interval in which the 2D nucleation of terraces is more likely than the bulk solidification. The nucleation mechanisms for 2D solidification are also analyzed in this work. More surprising is the terrace behaviour above bulk the melting temperature. The terraces can be slightly overheated before they melt. The melting does not occur all over the surface as a single event; instead small drops form at the terrace edge. Subsequently these drops move on the surface "eating" the solid terraces on their way. By this they grow in size leaving behind paths from were the material was collected. Both overheating and droplet movement can be explained by the fact that the alkane melt wets only partially its own solid. For the first time, these results explicitly confirm the supposed connection between the absence of overheating in solid and "surface melting": the solids usually start to melt without an energetic barrier from the surface at temperatures below the bulk melting point. Accordingly, the surface freezing of alkanes give rise of an energetic barrier which leads to overheating. / Sowohl Benetzung als auch Phasenübergänge spielen eine sehr wichtige Rolle im täglichen Leben. Molekular dünne Filme langkettiger Alkane an Festkörper/Gas-Grenzflächen (z. B. C30H62 an Silizium-Waferoberflächen) sind sehr gute Modellsysteme um die Wechselbeziehung zwischen Benetzungsverhalten und (Volumen-)Phasenübergängen zu untersuchen. In einem Temperaturbereich knapp oberhalb der Volumenschmelztemperatur benetzt die Alkanschmelze die Substratoberfläche nur partiell (Alkantropfen). In diesem Temperaturbereich ist die Substratoberfläche mit einer molekular dünnen, festkörperartig geordneten Alkanschicht bedeckt ("Oberflächengefrieren" ). Die Alkanschmelze benetzt also die eigene Festkörperoberfläche nur partiell, ein in der Natur ziemlich seltenes Phänomen. Die Dissertation beschäftigt sich damit wie die Alkanschmelze ihre eigene Festkörperoberfläche über und unter dem Volumenschmelzpunkt benetzt und mit den entsprechenden Vorgängen beim Schmelzen bzw. Erstarren. Flüssige Alkantropfen lassen sich einige Grad unter ihren Schmelzpunkt unterkühlen ohne sich sofort zu verfestigen. Dieses "Unterkühlungsverhalten" ist üblich und es ist theoretisch qualitativ gut verstanden. Allerdings beobachtet man bei den Alkanen bei leichter Unterkühlung statt einer eventuellen Volumenverfestigung oft die Ausbildung von zweidimensionalen Terrassen aus erstarrtem Alkanen. Die Terrassen wachsen auf der Substratoberfläche radial aus den flüssigen Tropfen. Sie bestehen aus wenigen Alkanlagen mit jeweils der Dicke einer Moleküllänge. Die Analyse der Terrassen-Wachstumsprozesse zeigt, dass die gesamte Substratoberfläche einschliesslich der Terrassen sowohl oberhalb als auch unterhalb der Volumenschmelztemperatur mit einer dünnen Schicht mobiler Alkanmoleküle bedeckt ist. Durch diese Schicht fliessen bei Unterkühlung die Alkane vom unterkühlten Tropfen zur Terrassenkante und liefern den Nachschub für deren Wachstum. Die Untersuchungen zeigen damit erstmalig die Koexistenz eines molekular dünnen Films ("Precursor") mit einer partiell benetzenden Volumenphase. Die Entstehung und das Wachstum der Terrassen wird nur in einem engen Temperaturfenster beobachtet in dem die Keimbildung zweidimensionaler Terrassen wahrscheinlicher ist als die dreidimensionale Volumenverfestigung. Auch dieses Keimbildungsverhalten wird in der Dissertation genauer analysiert. Noch erstaunlicher als das Terrassenwachstum, d. h. das Verfestigungsverhalten ist das Schmelzverhalten der Terrassen. Sie lassen sich bis zu einer gewissen Temperatur überhitzen bevor sie schmelzen! Weiterhin findet bei genügender Überhitzung das Schmelzen nicht gleichzeitig überall statt sondern es entstehen zuerst kleine Alkantropfen an den Terrassenrändern. Diese bewegen sich dann über die Substratoberfläche und "fressen" sich durch die festen Terrassen. Dabei wachsen sie weil sie das geschmolzene Material aufnehmen und hinterlassen eine alkanfreie Spur. Sowohl die Überhitzung als auch die Tropfenbewegung lassen sich damit erklären dass die flüssige Alkanschmelze ihren eigenen Festkörper nur partiell benetzt. Die Ergebnisse bestätigen erstmals explizit den seit vielen Jahrzehnten vermuteten Zusammenhang zwischen der üblicherweise nicht beobachtbaren Überhitzung von Festkörpern und Oberflächenschmelzen: Festkörper beginnen normalerweise ohne Energiebarriere von der Oberfläche an zu schmelzen. Entsprechend bildet das Oberflächengefrieren der Alkane eine Energiebarriere und erlaubt damit deren Überhitzen.

Die Methodik der DIN 4108-2 zur Bewertung der Überhitzungswahrscheinlichkeit eines kritischen Raumes entspricht nicht mehr den wissenschaftlichen und technischen Standards. Die Kritik in der Fachliteratur hat zugenommen. Im vorliegenden Artikel werden die Hintergründe der DIN 4108-2 erläutert und bekannte Anwendungsgrenzen und Unzulänglichkeiten aus der Literatur zusammengefasst. Diese betreffen sowohl angenommene Randbedingungen als auch die Abbildung der relevanten physikalischen Effekte und Bewertungsgrößen. Darüber hinaus wird dargelegt, dass Gebäudenutzung, Raumeigenschaften und Klima als relevante Kategorien in der Betrachtung des Überhitzungsrisikos differenzierter abgebildet werden müssen. Anhand von fünf Praxisbeispielen werden Widersprüche zwischen Ergebnissen des vereinfachten Sonneneintragskennwerte-Verfahrens, Simulationen mit Randbedingungen gemäß DIN 4108-2 und Simulationen mit gebäudespezifischen Randbedingungen aufgezeigt. Anhand eines Vergleiches von Mess- und Simulationsergebnissen für einen dieser Beispielräume werden auch Grenzen der Simulationsrechnungen angesprochen. Ziel der Darstellung ist es, zwischen der wissenschaftlichen Diskussion, die von stark idealisierten Fällen getragen ist, und den planerischen Herausforderungen der Praxis, in welcher die Anwendbarkeit dieser Nachweisansätze oft unklar ist, zu vermitteln.

The energy used in non-domestic buildings accounts for 18 % of the energy use in the UK. Within the non-domestic building stock, 11 % of office buildings have a very high influence on the energy use. Thus, the retrofit of office buildings has a significant potential for energy efficiency and greenhouse gas emissions reduction within the non-domestic building stock. However, the replacement rate of existing buildings by new-build is only around 1-3 % per annum. Post-war office buildings, (built between 1945 and 1985) represent a promising sector for retrofit and energy demand reduction. They have disproportionately high energy consumption because many were built before the building regulations addressed thermal performance. The aim of the research is to evaluate the retrofit strategies for post-war office buildings accounting for the improved energy efficiency, thermal comfort and hence, productivity, capital and the running costs. The research seeks to provide the optimal generic retrofit strategies and illustrate sophisticated methods which will be the basis for guidelines about post-war office building retrofit. For this, multiple combinations of heating and cooling retrofit measures were applied to representative models (Exemplar) of post-war office buildings using dynamic thermal simulation modelling. The retrofit strategies include; applying envelope retrofit to UK Building Regulations Part L2B and The Passivhaus Institue EnerPHit standards for heating demand reduction and winter comfort. Passive cooling interventions such as shading devices and night ventilation and active cooling intervention such as mixed-mode ventilation were applied to overcome summer overheating. All retrofit combinations were evaluated considering future climate, inner and outer city locations and different orientations. In summary, the results showed that under current weather conditions Part L2B standard retrofit with passive cooling provided the optimum solution. In 2050, however, both Part L2B retrofit naturally ventilated cases with the passive cooling measures and EnerPHit retrofit mixed-mode ventilation cases provide the requisite thermal comfort and result in a similar range of energy consumption. It was concluded that to create generic retrofit solutions which could be applied to a given typology within the building stock is possible. The methodology and the Exemplar model could be used in future projects by decision-makers and the findings and analysis of the simulations could be taken as guidance for the widespread retrofit of post-war office buildings.

This master’s thesis deals with the issue of damage of the vehicle’s drivetrain due to the operating fluid leakage. The aim of the thesis is to clarify the severity of this type of damage and, alternatively, the times during which these failures can occur. The theoretical part describes the issues of lubrication and cooling systems, including the consequences of sub-optimal operating conditions. The evaluation is based on conducted experiments and is compared with already published tests. The parts that are most often damaged are also described. Finally, the recommendations for lowering the extent of damage are formulated.

Wave power has been increasing the interest of many researchers looking for alternative sustainable energy sources since the reserves have proved to be capable of satisfying a considerable percentage of the world´s energy demands. This option has not been adopted as a sustainable source since there are some challenges in the process of designing a low cost device that converts the kinetic energy of the waves into electric energy and that could still be efficient enough to be competitive against other options. A new proposal from Anders Hagnestål looks like a very promising way of moving forward in this field. The structure of this newly proposed generator includes neodymium magnets that at temperatures over 60°C might suffer irreversible demagnetization, compromising the normal functioning of the machine. Because of the electrical losses in iron components, overheating is a possibility that must be studied. The aim of this study is to find the temperature distribution of the components that are subject to changing magnetic fields (where the losses will occur). This will be done for a variety of cases regarding environmental and working conditions with the purpose of determining if the generator will need a cooling technique to avoid damage to the magnets. The studied structure consists of a stator and a translator conformed by iron, FR4, glass fiber and, of course, the magnets. The task at hand was carried out first through a one-dimensional analytical model, then through a two-dimensional analytical model and finally by means of simulations on Comsol Multiphysics (Computer-Aided-Engineering software). All of the aforementioned methods implicate assumptions that deviate from reality, but are still useful for the task at hand. Results from the 1D calculation turned out to be unreliable due to the numerous approximations but helped to prove and understand the effect of each of the environmental conditions on the temperature distribution. On the other hand, the 2D calculations and the simulations had a very good agreement which provides some reliability. Furthermore, said results showed that the components might even reach temperatures as high as 380°C under certain conditions. As this number is clearly over the safe limit of the magnets, it was concluded that cooling techniques are needed to ensure the safety of the generator. After some discussion with Hagnestål, cooling methods were proposed. In addition to this, the seemingly most appropriate option was pointed out with the intention of achieving a low-enough temperature and keeping the costs as low as possible. This alternative was a combination of modifying geometric parameters (which would ultimately reduce heat generation) and inducing a low velocity air flow. / Vågkraft är en hittills outnyttjad förnybar energikälla som i framtiden kan tillgodose i storleksordningen 10 % av världens energibehov, om de tekniska utmaningarna kan lösas så att vågkraft kan levereras till konkurrenskraftiga priser. Därmed finns också ett starkt intresse från både akademi och näringsliv att lösa dessa utmaningar. Anders Hagnestål håller på att utveckla en ny linjär generatortyp som enligt beräkningar slår alla befintliga lösningar för effektomvandling för vågkraft med bred marginal. Maskinen har dock komplex geometri, och det är svårt att beräkna dess prestanda. Maskinen innehåller neodymmagneter, vilka kan avmagnetiseras om de blir för varma där 60°C kan ses som en gräns då magneterna börjar påverkas. Om magneterna avmagnetiseras blir maskinen svagare. Eftersom magneterna upphettas av virvelströmmar i magneterna och förluster i omgivande elektroplåt, är det av intresse att göra en termisk analys av maskinen vilket är syftet med detta examensarbete. Målet är att beräkna temperaturutbredningen i maskinens olika delar vid olika driftsfall, och se om man behöver tillföra extern kylning av maskinen för att skydda magneterna. Maskinen består av en translator som omsluter den inre statorn där magneterna är lokaliserade, vilka är byggda av fiberkompositer, elektroplåt, rostfritt stål och neodymmagneter. Beräkningar gjordes först med en endimensionell analytisk modell, därefter med en tvådimensionell analytisk modell och slutligen med numeriska beräkningar i 2D med det kommersiella finita elementmetodberäkningsprogrammet Comsol Multiphysics. Samtliga dessa modeller har avvikelser från det verkliga fallet, men är ändå användbara och ger en fingervisning om hur den termiska situationen för maskinen kan se ut. 1D-beräkningarna visade sig innehålla lite för grova approximationer för att ge pålitliga resultat, men gav en del intuitiv insikt om problemet. Den analytiska 2D-beräkningen stämde bra överens med Comsol-beräkningen, vilket indikerar att beräkningarna är korrekta. Resultaten visade på mycket höga temperaturer i vissa driftsfall utan kylsystem, 380 °C, vilket är en indikator på att antingen någon form av kylning förmodligen behövs, i.a.f. i en del driftsfall, eller att värmeförlusterna i den delen av generatorn behöver minskas genom t.ex. att pollängden ökas. En kombination av luftflöden med låg hastighet och förändrad geometri har föreslagits i examensarbetet för att minska temperaturen.

Der Immobiliensektor trägt maßgeblich zur Treibhausgasemission bei und muss daher in den kommenden Jahren wesentlich verändert werden, um die notwendigen Einsparungen zu erzielen. Im Rahmen dieses Beitrags werden erste Untersuchungen dargestellt, den Wohnimmobilienmarkt mittels verschiedener Geosensoren zu erfassen, um aus den visuell erfassbaren Eigenschaften sowie geometrischen Informationen von Gebäuden Aussagen zu energetischen Zuständen von Immobilien zu tätigen. Dazu ist im Zuge eines Kooperationsprojekts der TU Dresden, der TU Clausthal, dem Fraunhofer IOSB-INA sowie der Geoinformationsbehörde des Kreises Lippe und dem Gutachterausschuss für Grundstückswerte im Kreis Lippe und in der Stadt Detmold eine Messkampagne durchgeführt worden. Im Rahmen dieser Messkampagne wurde eine Begehung durch Immobilienexperten sowie eine terrestrische und drohnenbasierte Erfassung mit RGB-Bildern, Laserscanning und Wärmebildern eines Quartiers durchgeführt. Die erfassten Eigenschaften von Immobilien werden in diesem Beitrag qualitativ diskutiert, um das mögliche Potenzial für eine automatisierte Bewertung des energetischen Zustands abzuschätzen. Durch empirische Untersuchungen sollen darüber hinaus die Werteinflüsse von energetischen Sanierungen auf die Verkehrswerte der Immobilien quantifiziert werden. Diese Information kann genutzt werden, um in etwaigen Förderprogrammen die Differenz zwischen den zu tätigenden Investitionen und dem dadurch hervorgerufenen Wertzuwachs zu fördern. In der vorliegenden Untersuchung kann gezeigt werden, dass Einschätzungen von Immobilienexperten zur Qualität von Immobilien zu guten Ergebnissen führen. Die genutzten Sensoren sind geeignet, Qualitäten und Schwächen von Immobilien aufzudecken, jedoch müssen die zeitlichen Konfigurationen der Aufnahmen optimiert werden.

Högskolan i Gävle planerar att installera solavskärmande markiser på entréhallarnas sydliga glasade fasader. Sedan uppbyggnad har entrébyggnaden som inkluderar ”Rävhallen” och ”Fårhallen” lidit av bristfällig termisk inomhuskomfort på grund av värmeläckage och överhettning orsakade av fasadernas fönsterpartier. Detta examensarbete gjordes i syfte att via mätningar undersöka den termiska inomhuskomforten i Högskolans i Gävle entréhallar. Arbetet syftade också till att årssimulera och analysera årlig energiförbrukning och termisk inomhuskomfort innan och efter installationen av solavskärmande markiser på byggnadens glasfasader, i simuleringsprogrammet IDA ICE. En komfortundersökning gjordes genom att mäta termisk komfort och inomhustemperaruter under två tillfällen i april månad. Mätningarna gjordes under en molnig dag och en solig dag vid samma utomhustemperatur, för att undersöka solinstrålningens inverkan på byggnadens termiska komfort och inomhustemperaturer. Komfortundersökningen visade att den termiska komforten i Rävhallen och Fårhallen var undermålig då överhettning uppstår vid hög solinstrålning. Nödvändiga data inför modellering och simulering insamlades genom observationer, uppskattning, beräkningar och samtal med drifttekniker vid Akademiska hus. Efter datainsamlingen konstruerades en modell i simuleringsprogrammet IDA ICE. Innan simulering validerades modellen med hjälp av tidigare uppmätta temperaturer under april månad. Sedan simulerades byggnadens energiförbrukning och termiska inomhuskomfort över ett helt år, utan markiser, och därefter med markiser. Resultatet visade att den termiska komforten förbättrades markant vid installation av markiser. Höga topptemperaturer som tidigare förekom i byggnaden minskade eftersom markiserna reducerade solinstrålningen genom fasadens fönsterpartier. Det totala årliga energibehovet ökade dock från 605 MWh till 635 MWh. Det årliga energibehovet för kyla minskade något från 3,4 MWh till 3,2 MWh. Att energiförbrukningen ökade berodde på att markiserna reducerade nyttig gratisvärme från solinstrålningen, särskilt under uppvärmningssäsong. För vidare forskning föreslås en mer effektiv styrteknik av markiserna och en mer detaljrik simuleringsmodell för att få tillförlitligare resultat. Vid tillämpning av bättre anpassad styrning av markiserna bedöms energibesparingspotentialen bli större. Slutsatsen drogs att markiser kan förbättra den termiska inomhuskomforten avsevärt, men att energiförbrukningen kan komma att öka beroende på styrteknik. / The University of Gävle plans to install solar shading awnings on the southern glass facades of the main entrances. Since construction, the main entrances Rävhallen and Fårhallen have suffered from poor thermal indoor comfort due to heat leakage and overheating due to the windows on the facades. This thesis was done in order to map and investigate the thermal indoor comfort in the University of Gävle's main entrances. The work also aimed to simulate and analyze annual energy consumption and thermal indoor comfort before and after the installation of solar shading awnings on the building's glass facades, in the simulation program IDA ICE. A comfort survey was conducted by measuring thermal comfort and indoor temperature ranges on two occasions in April. The measurements were made during a cloudy day and a sunny day at the same outdoor temperature, to investigate the effect of solar radiation on the building's thermal comfort and indoor temperatures. The comfort survey showed that the thermal comfort in Rävhallen and Fårhallen was insufficient as overheating occurs at high solar radiation. Data necessary for modeling and simulation was collected through observations, estimates, and dialogs with operating technicians from Akademiska hus. After data collection, a model was constructed in the simulation program IDA ICE. Before simulation, the model was validated using previously measured temperatures during the month of April. Then the building's energy consumption and thermal indoor comfort were simulated over a whole year, without awnings, and with awnings. The results showed that the thermal comfort was significantly improved by the awnings installations. High peak temperatures that previously occurred in the building decreased because of the reduced solar radiation through the glass facade. The total annual energy demand increased from 605 MWh to 635 MWh. However, the annual energy demand for cooling decreased from 3,4 MWh to 3,2 MWh. The increase in energy consumption was due to the awnings reducing useful heat from solar radiation, especially during the heating season. Prior to further research, a more efficient control technique of the awnings and a more detailed model to improve the simulation results are proposed. When applying better adapted control of the awnings, the energy saving potential is considered to be greater. It was concluded that awnings can significantly improve indoor thermal comfort, but that energy consumption may increase depending on control technology.

The doctoral research revolves around a comparative study of timber modern methods of construction for low-rise, residential buildings in Scotland. The building techniques studied involve both timber-frame panel construction (open-panel and closed-panel systems and structural insulated panels) and massive-timber construction (cross-laminated and nail-laminated timber panels). A non-timber technique is also included in the study: more traditional, load-bearing masonry (blockwork). These different building techniques have been analysed from two complementary aspects: environmental impacts and thermal performance. The environmental study is based on the life-cycle assessment methodology and embraces various aspects: environmental impacts (e.g., climate change, acidification, eutrophication, ozone depletion, etc.), consumption of energy (renewable and non-renewable resources) and production of waste (from non-hazardous to radioactive). The assessment takes a cradle-to-gate approach and, in its structure and method, is informed by the current recommendations of the international standards in the field (i.e., ISO 14040 series). Various environmental trade-offs between construction methods have been identified. In terms of global-warming potential (excluding biogenic carbon sequestration), results suggest that timber-frame buildings show a better performance than masonry buildings; this is particularly true for the open-panel system, which emits about 10% less carbon than the masonry counterpart. Massive-timber buildings tend to cause more carbon emissions than masonry ones. In terms of consumption of non-renewable primary energy, timber buildings do not generally show significant advantages with respect to blockwork-based masonry. In particular, structural-insulated panel systems tend to show very high energy requirements. Timber-based buildings show a tendency to cause increased acidification, eutrophication and creation of low ozone than their masonry counterpart. The level of offsite fabrication that is employed for the erection of the buildings plays an important role in the magnitude of most environmental impacts, which show an average decrease between 5% and 10% when some of the operations are shifted from the construction site to the factory. v The thermal study investigates the performance of the building envelope, and, in particular, of external walls, by means of tests whereby the thermal behaviour of a sample of walls (of full-size section) has been observed and measured over time. On the outside, the walls were exposed to real, natural weather variations throughout the summer. The study especially focuses on the time-dependent response of three different walling systems (which results from their individual cross-sectional arrangements of building components and the associated combination of heat-storage capacity and thermal resistance): a timber-framed wall, a cross-laminated-timber wall and a masonry wall. Thus, the main goal of the study was to characterise the thermal-inertia parameters of these walls. This type of thermal behaviour is related to the repercussions of global climate change at UK level, especially in terms of increase in solar irradiance and temperature, which requires an adaptation of the building-envelope such that it can perform well both during wintertime and summertime, by providing maximum indoor comfort with minimum economic and environmental costs from the construction and operation of buildings. The timber-framed wall possesses the greatest capacity to slow down the propagation of temperature waves from the outer surface to the inner surface (time lag), whereas the masonry wall performs best with respect to reducing the amplitude of temperature oscillation on the inner surface (decrement factor). The cross-laminated-timber wall exhibits intermediate values of both time lag and decrement factor, relative to the other two walls. Both the thermal and life-cycle assessment of the construction alternatives aim at assisting the design and decision-making process in the residential field and at suggesting areas that need to be addressed and improved, towards a coherent evolution of the building techniques included in this study and a step forward in the realisation of sustainable, low-rise dwellings.

Cette thèse s’inscrit dans le cadre des études des phénomènes électromagnétiques dansles régions frontales des grands turbo-générateurs. L’objectif de la thèse est d’estimer apriori le champ magnétique axial en fonction du point de fonctionnement afin d’éviterles possibles dégradations du circuit magnétique (dus aux points chauds et tensions entretôles, qui sont liés à la composante axiale du champ).Une maquette à échelle réelle a été spécialement conçue et réalisée dans le but d’améliorerla compréhension physique des phénomènes : les pertes, la pénétration du champ magnétiqueet les tensions entre tôles sont analysés.Les simulations par éléments finis sont ensuite utilisées : les avantages et inconvénientsseront discutés, ainsi qu’une comparaison critique des résultats par rapport aux mesuresexpérimentales sur la maquette. La région frontale d’un turbo-alternateur est aussi entièrementmodélisée.Enfin, un modèle simple du flux axial est développé. Ses coefficients sont déterminés àl’aide de simulations par éléments finis, mais il peut ensuite être utilisé en temps réel afind’estimer le flux axial correspondant à un point de fonctionnement quelconque. / This work aims to improve the knowledge of electromagnetic phenomena that occurin the end region of large turbo-generators. The goal of this work is to evaluate theaxial magnetic flux density with regard to the operating conditions (such as active orreactive power) in order to prevent potential deterioration of the stator. Indeed, the axialmagnetic field is known to induce hot points or voltages between laminations that maycause insulation breakdown and thus stator faults.An experimental apparatus in real scale has been designed and built. Its purpose is tostudy precisely the following phenomena: losses, axial magnetic flux density penetration,voltage across adjacent voltages.Finite element simulations (FEM) are also used: their advantages and drawbacks arediscussed, and the results are compared with the experimental measures. The wholeend-region of a turbo-generator is also simulated.Finally, a simple model of the axial magnetic flux is proposed. Its parameters are basedon the results of the FEM model, but it may be used in real time to evaluate the axialmagnetic flux density of any operating point.

This thesis deals with problematics of installing wireless routers into specific locations depending on their heating and ideal signal transmission. The thesis is divided into eight chapters. The beginning of the thesis is theoretical describes the introduction into the problematics, the second part is practical and covers the executed experiment. The theoretical part contains six chapters – heat, signal, wireless router and measured climatic conditions. The practical part describes the executed experiment by thermo-camera which was used to scan wireless routers in IoT Lab in Avast Software company. Based on this experiment, the ideal position for installing the wireless router is then established. The conclusion of the practical part includes an analysis of the results of the questionnaire survey, in which technically skilled people were asked to describe the height of installation of their wireless router or whether did they consider heat and signal propagation while installing their wireless routers.