A aplicação de materiais cerâmicos na indústria têxtil, em especial nos processos de produção e modificação de fios é amplamente difundida no mundo. O fator chave para definição da necessidade do uso de um material cerâmico é a abrasividade dos fios associada à velocidade de processamento desse material. Nesse estudo foi focado o processo de texturização por falsa torção, e foi proposto analisar e compreender o impacto da variação de rugosidade de discos de cerâmica (que já tenham sofrido desgaste durante o processamento), sobre as características físicas de um fio de poliamida. Para isso efetuou-se a seleção de discos de cerâmica com diferentes faixas de rugosidade, fixou-se todas demais variáveis da máquina de texturização, e foram produzidos fios em cada uma das faixas. Depois de produzidos, os fios foram submetidos a testes físicos laboratoriais, e os resultados analisados pelo método ANOVA. Foi observado que a variação na rugosidade dos discos afetou principalmente as características de volume do fio (EKB%), não afetando significativamente o alongamento e tenacidade. / Use of ceramic materials in the textile industry, particularly in production and converting processes of yarns is widespread in the world. The key factor which defining the use of a ceramic material is the abrasiveness of the yarns associated by processing speed of the material. This study focused the false twist texturing, and has been proposed to analyze and understand the impact of variation in roughness of ceramic discs (which have already undergone wear during processing) on the physical characteristics of a polyamide yarn. So, the ceramic discs have been selected with different ranges of surface roughness, settled all other variables of the texturing machine, and each yarn were produced in each of the ranges. Once produced, the yarns were subjected to physical testing laboratory, and the results were analyzed by ANOVA. This study indicated that the variation in roughness of the disks mainly affected the characteristics of the yarn crimp (EKB%) not significantly affecting the elongation and tenacity.

Made available in DSpace on 2016-02-26T14:53:08Z (GMT). No. of bitstreams: 1 ClaudiaBezerraSGoncalves.pdf: 706994 bytes, checksum: 7b1a77a7f4ff1c1b643ddf918c282667 (MD5) Previous issue date: 2007-02-28 / Most part of the external sensory receptaclles known are located in the antennal flagellate: sensilla placodea (olfactory discs, D.O.), basiconica, trichodea (cerdas), coeloconica, ampullaceae and campaniformia. The Apidae bees have been studied on diverse aspects, the external morphology, among which has call the attention for its importance is the bee antennae. The study of the antennae and their sensory olfactive structures has been done more frequently in highly social bees, such as Apina and Meliponina. The purpose of the paper was to analyze comparatively, at microscopic level, the size and the form of the antenna, the number and the distribution of the olfactory antennal structures or sensilla placodea in Euglossina and Meliponina bees with different social standards It was antennae from 10 males of Melipona favosa orbignyi and of Scaptotrigona depilis, 10 males of Eufriesea violaceae and of Exaerete smaragdina and 2 males of Exaerete dentata, totaling 62 bees analyzed for each species studied. For segment was counted the absolute number of the olfactory discs, it was measured diverse morphometric characters and obtained the following values AT (total area of the segment) aE (area with D.O), a (area with D.O.) and it was calculated the indices D.O./AT and D.O/aE. It was the Euglossina bees have more D.O., related to absolute numbers than the Meliponina. Among the Meliponina, the males and the workers the M. favosa orbignyi 5 have more absolute number of D.O., and comparing sex, the males have more D.O. than the females. As for the characters A (width of the segment) D and E (length of the segment), the Euglossina male show more value when compared to the workers and males of the Meliponina. As for the area of the antennal segment, Euglossina males present a total area AT much bigger than Meliponina. Among all the species analyzed, Euglossina show an area with olfactive structure (aE) and an area without theses D.O. (a) with similar sizes; while Meliponina, aE > a. Among the Meliponina, S. depilis have more discs (D.O./AT) with more concentration on the segment (D.O./aE) among the males, theses values are bigger than the females. The worker, M. favosa orbignyi, show theses indices much bigger than the males, indicating more quantity of D.O. with more concentration in the segment. Among all Euglossina, the males of Eufriesea violaceae have more D.O. than E. dentata and E. smaragdina (both with lower values than the Meliponina). Hence S. depilis, despite its smaller size, have the bigger number of D.O. than the Euglossina, Eufriesea violaceae have bigger number D.O. than the Exaerete (which are considered big bees and bigger than Eufriesea violaceae) / No flagelo antenal se encontra a maior parte de receptores sensoriais externos conhecidos: sensilla placodea (discos olfativos, D.O.), basiconica, trichodea (cerdas), coeloconica, ampullacea e campaniformia. Nas abelhas Apidae, têm sido estudadas sob os mais diversos aspectos, a morfologia externa, sendo que um dos caracteres que tem chamado a atenção pela sua importância é a antena das abelhas. O estudo das antenas e de suas estruturas sensoriais olfativas tem sido realizado com mais intensidade em abelhas altamente sociais, como nos Apina e Meliponina. O objetivo do trabalho foi analisar comparativamente, em nível de microscopia óptica, o tamanho e forma da antena, o número e a distribuição das estruturas olfativas antenais ou sensilla placodea em abelhas Euglossina e Meliponina com diferentes padrões sociais. Foram usadas antenas de 10 machos e 10 fêmeas de Melipona favosa orbignyi e de Scaptotrigona depilis; 10 machos de Eufriesea violaceae e de Exaerete smaragdina e, 2 machos de Exaerete dentata, totalizando 62 abelhas analisadas para cada espécie estudada. Para cada segmento foi contado o número absoluto de discos olfativos, foram medidos diversos caracteres morfométricos e obtidos os valores AT (área total do segmento), aE (área com D.O. ), a (área sem D.O.), e ainda, calculados os índices D.O./AT e D.O./aE. Verificou-se que as abelhas Euglossina têm mais D.O., em números absolutos, do que as Meliponina. Dentre os Meliponina, os machos e as operárias de M. favosa orbignyi tem maior número absoluto de D.O., e, na comparação entre os sexos, os machos possuem mais D.O. do que as fêmeas. 3 Referente aos caracteres A (largura total do segmento) D e E ( relativos ao comprimento do segmento), os maiores valores são apresentados pelos machos Euglossina, quando comparados com operárias e machos de Meliponina. Quanto às áreas do segmento antenal, os machos Euglossina apresentam a área total AT muito maior do que em Meliponina. Dentre todas as espécies analisadas, os Euglossina mostram a área com estruturas olfativas (aE ) e a área sem esses D.O.(a) com tamanhos semelhantes; enquanto que nos Meliponina, aE > a. Dentre os Meliponina, S. depilis têm mais discos (D.O./AT), com maior concentração no segmento (D.O./aE) sendo que nos machos, esses valores são maiores do que nas fêmeas. As operárias M. favosa orbignyi mostram esses índices bem maiores do que nos machos, indicando maior quantidade de D.O., com maior concentração no segmento. Dentre todos os Euglossina, os machos de Eufriesea violaceae têm mais D.O. do que E. dentata e E. smaragdina (ambos com valores inferiores aos dos Meliponina). Portanto S. depilis, independente de seu tamanho menor, têm o maior número de discos olfativos; e dentre os Euglossina, Eufriesea violaceae têm maior número de D.O. do que as Exaerete (que são consideradas abelhas de grande porte, e maiores que Eufriesea violaceae)

The goal of the diploma thesis is to create a business valuation based on investment value of GZ Digital Media, a.s. The date of business valuation is on 1 st January 2015 for purpose of hypothetical sale of the majority shareholder´s share. At first, diploma thesis introduces the company itself. After that, the strategic and financial analyses follows. On these analyses is determined whether the assumption of going concern is fulfilled or not. The company is valuated with the DCF entity and industry multiples methods. After that the value of majority shareholder´s share is determined.

Detta arbete undersöker om metoden ’laser cladding’ skulle kunna användas för att möjliggöra återanvändandet av bromsskivor som annars skulle deponeras. Olika material undersöks ur ett miljöperspektiv, det vill säga energiåtgång och CO2-utsläpp jämförs mot en vanlig gjutjärnsskiva. För att göra detta användes programmet CES EduPack samt ytterligare beräkningar med formler som komplement då programmets databas inte är heltäckande gällande specifika materialvarianter. För att lättare kunna beräkna massor användes CAD-programmet Solid Edge för att modellera en typisk bromsskiva. Resultatet blev att laserbeläggning på utslitna bromsskivor sparar på både energi och avger mindre CO2-avtryck, förutsatt att rätt tillsatsmaterial väljs. Som mest kunde en minskning med 80,5% uppnås i energiåtgång respektive 88% för CO2-utsläpp under materialframställning och tillverkning. Metoden medför alltså tydliga positiva miljömässiga effekter. / This report investigates Laser Cladding and especially the possibility to coat worn brake discs. A selection of materials are studied with an environmental point of view in focus, the life cycle of the coated brake discs are compared to a standard new gray cast iron brake disc. The program CES Edupack is used for the life cycle analysis and it is completed by formulas of energy consumption and CO2 footprint because not all processes and materials are included in the software. Solid Edge is used to create a CAD model of a typical brake disc to easily exam the volume and weight of the disc as a function of the thickness. The result is laser cladding on worn brake discs saves energy and produces a smaller carbon footprint if the right powders used for cladding are chosen. Laser cladding with stainless steel powders provided the best results with 80.5% savings in energy consumption and 88% in CO2-footprint savings. The laser cladding technique shows clear positive environmental effects.

No description available.

<p>We use numerical simulations to examine the fragmentation of protostellar discs via gravitational instability (GI), a proposed formation mechanism for gas-giant planets and brown dwarfs. To accurately model heating and cooling, we have implemented radiative transfer (RT) in the TreeSPH code Gasoline, using the flux-limited diffusion approximation coupled to photosphere boundary cooling. We present 3D radiation hydrodynamics simulations of discs that are gravitationally unstable in the inner 40 AU; these discs do not fragment because the cooling times are too long. In prior work, one of these discs was found to fragment; however, we demonstrate that this resulted from an over-estimate of the photosphere cooling rate. Fragmentation via GI does not appear to be a viable formation mechanism in the inner 40 AU.</p> <p>We also present simulations of GI in the outer regions of discs, near 100 AU, where we find GI to be a viable formation mechanism. We give a detailed framework that explains the link between cooling and fragmentation: spiral arms grow on a scale determined by the linear gravitational instability, have a characteristic width determined by the balance of heating and cooling, and fragment if this width is less than twice their Hill radius. This framework is consistent with the fragmentation and initial fragment masses observed in our simulations. We apply the framework to discs modelled with the commonly-used beta-prescription cooling and calculate the critical cooling rate for the first time, with results that are consistent with previous estimates measured from numerical experiments.</p> <p>RT is fundamentally important in the star formation process. Non-ionizing radiation heats the gas and prevents small-scale fragmentation. Ionizing radiation from massive stars is an important feedback mechanism and may disrupt giant molecular clouds. We present methods and tests for our implementation of ionizing radiation, using the Optically-Thin Variable Eddington Tensor method.</p> / Doctor of Philosophy (PhD)

Denna rapport avser det examensarbete som har utförts i samarbete med AB Volvo Penta under vårterminen 2022. Arbetet beskriver produktutvecklingsprocessen för en lamellprovrigg.Volvo Penta i Köping utvecklar och tillverkar transmissioner för marint bruk. De har problem att få noggranna mätningar av effektförluster i lamellpaketen som sitter i transmissionen. Därför önskar Volvo Penta en lamellprovrigg för att kunna mäta effektförlusterna i ett frånkopplat lamellpaket. Projektet avgränsas till att endast ta fram en layoutkonstruktion med val av huvudkomponenter och funktionsbeskrivning för lamellprovriggen.Innan produktutvecklingsprocessen påbörjades gjordes en förstudie för att granska befintliga lamellprovriggar. Förstudien konkluderas med att dagens lamellprovriggar inte kan utföra tester under de driftförhållanden som önskas i den provrigg som examensarbetet avser konstruera, därför kan endast huvudkomponenter i tidigare lamellprovriggar granskas och inte hela provriggskoncepten. Genom konceptgenerering och -utvärdering tas en layoutkonstruktion fram och huvudkomponenter specificeras. Motrotation på lamellpaket skapas med Duoprop-system. Förlustmätningar av moment samt värmeutveckling utförs. Mätning av både moment och varvtal görs med ett momentnav som är placerad vid motorn för att mäta det som förs in i systemet. Temperatur och flöde mäts på flera ställen i hydraulsystemet för att kunna variera det önskade driftförhållandet.Resultatet är underlag till en provrigg som efterliknar Volvo Pentas IPS-transmissions driftförhållanden och ger möjlighet till provning av nya material, oljor och dimensioner. Konstruktionens avsikt är att ge underlag på en layout av en lamellprovrigg som lämpar sig till Volvo Pentas fysiska och teoretiska behov. Konstruktionen är genomarbetad och bör vara en stabil byggsten för kommande arbete fram till tillverkning och montering. / This report refers to the bachelor’s thesis that has been carried out in collaboration with AB Volvo Penta during the spring term 2022. The work describes the product development process for a wet disc clutch test rig.Volvo Penta in Köping develops and manufactures transmissions for marine applications. Their problem is getting accurate measurements of power losses in the wet clutch packages contained in the transmission. Volvo Penta therefore have the desire for a wet disc clutch test rig to be able to measure the power losses in a disconnected friction disc package. The project is limited to developing only a layout design with a selection of main components and a functional description for the wet disc clutch test rig.Before the product development process began, a feasibility study was conducted to examine existing friction disc test rigs. The feasibility study concludes that today's test rigs can not perform tests under the desired operating conditions in the test rig that the degree project intends to construct, therefore only main components in previous test rigs can be examined and not the entire test rig concept. Through concept generation and evaluation, a layout construction is developed and the main components to it are specified. Counter-rotation on friction disc packages is created with a Duoprop-system. Loss measurements are performed for torque and heat generation. Measurements for both torque and rotational speed are done with a torque sensor that is located at the engine to measure what is fed into the system. Temperature and flow are measured in several places throughout the hydraulic system in order to be able to vary the desired operating conditions.The result is the basis for a wet disc clutch test rig that mimics Volvo Penta's IPS transmission’s operating conditions and provides an opportunity to test new materials, oils and dimensions. The purpose of the design is to provide a basis for a layout of a wet disc clutch test rig that suits Volvo Penta's physical and theoretical needs. The construction has been thoroughly evaluated and should be a stable building block for future work until manufacturing and assembly.

The last twenty-five years have seen our understanding of the formation and abundance of planets revolutionised, thanks to the first detections of debris discs, and, a decade later, of the first extrasolar planets. Hardly a week now goes by without a planet discovery, and the range of methods used to search for planets has expanded to include techniques that are efficient at detecting different types of planets. By combining the discoveries of the various methods, we therefore have the opportunity to build a picture of planet populations across the Galaxy. In this thesis, I am presenting work done as a basis towards such an effort: first I present work carried out to improve modelling methods for gravitational microlensing events. Since the first microlensing observing campaigns, the amount of data of anomalous events has been increasing ever faster, meaning that the time required to model all observed anomalous events is putting a strain on available human and computational resources. I present work to develop a method to fit anomalous microlensing events automatically and show that it is possible to conduct a thorough and unbiased search of the parameter space, illustrating this by analysing an event from the 2007 observing season. I then discuss the possible models found with this method for this event, and their implication (Kains et al. 2009), and find that this algorithm locates good-fit models in regions of parameters that would have been very unlikely to be found using standard modelling methods. Results indicate that it is necessary to use a full Bayesian approach, in order to include prior information on the parameters. I discuss the analytical priors calculated by Cassan et al. (2009) and suggest a possible form of an automatic fitting algorithm by incorporating these priors in the algorithm used by Kains et al. (2009). Another topic with which this thesis is concerned is the evolution of debris discs around solar-type stars. Late-type stars are expected to be the most numerous host stars of planets detected with the microlensing technique. Understanding how their debris discs evolve equates to understanding the earliest stages of planet formation around these stars, allowing us to truly put our Solar System in perspective. Using the analytical model of Wyatt et al. (2007a), I modelled the evolution of infrared excess flux at 24 and 70 microns using published data of debris discs around solar-type (spectral types F, G and K) stars from the Spitzer Space Telescope. By comparing the results of this study to an analogous study carried out by for A stars by Wyatt et al. (2007b), I find that although best-fit parameters are significantly different for solar-type stars, this may be due to the varying number of inefficient emitters around stars of different spectral types. I suggest that although effective properties are different by an order of magnitude or more, intrinsic properties, while still different, are so by a much smaller factor. These differences may be due to the longer timescales over which solar-type stars evolve, which allow for the formation of larger and stronger planetesimals.

This thesis describes efforts to improve the realism of numerical models of giant planet formation and migration in an attempt to better understand these processes. A new approach has been taken to the modelling of accretion, designed to mimic reality by allowing gas to accumulate upon a protoplanetary surface. Implementing this treatment in three-dimensional self-gravity radiation hydrodynamics calculations provides an excellent model for planet growth, allowing an exploration of the factors that affect accretion. Moreover, these calculations have also been extended to investigate the migration of protoplanets through their parent discs as they grow. When focusing on the growth of non-migrating protoplanets, the models are performed using small sections of disc, enabling excellent resolution right down to the core; gas structures and flow can be resolved on scales from ~ 10^4 to 10^11 metres. Using radiative transfer, these models reveal the importance of opacity in determining the accretion rates. For the low mass protoplanets, equivalent in mass to a giant planet core (~ 10 M⊕), the accretion rates were found to increase by up to an order of magnitude for a factor of 100 reduction in the grain opacity of the parent circumstellar disc. However, even these low opacities lead to growth rates that are an order of magnitude slower than those obtained in locally-isothermal conditions. For high mass protoplanets (>~ 100M⊕), the accretion rates show very little dependence upon opacity. Nevertheless, the rates obtained using radiative transfer are still lower than those obtained in locally-isothermal models by a factor of ~2, due to the release of accretion energy as heat. Only high mass protoplanets are found to be capable of developing circumplanetary discs, and this ability is dependent upon the opacity, as are the scaleheights of such discs. However, their radial extents were found to be independent of the opacity and the protoplanet mass, all reaching ≈ RH/3, inline with analytic predictions. Migration is investigated using global models, ensuring a self-consistently evolved disc. Using locally-isothermal calculations, it was found that the capture radius of an accreting sink particle, used to model a protoplanet without a surface, must be small (<< RH) to yield migration timescales consistent with linear theory of Type I migration. In the low mass regime of Type I migration, accreting sinks with such small radii yield timescales consistent with those models in which a protoplanetary surface is used. However, for high mass protoplanets, undergoing Type II migration, the surface treatment leads to faster rates of migration, indicating the importance of a realistic accretion model. Using radiative transfer, with high opacities, leads to a factor of ~ 3 increase in the migration timescale of the lowest mass protoplanets, improving their chances of survival. As suitable gas giant progenitors, their survival is key to understanding the growth of giant planets. An unexpected result of the radiative transfer was a reduction in the migration timescale of high mass planets. This appears to be a result of the less thoroughly evacuated gaps created by planets in non-locally-isothermal discs, which affects the corotation torque.

Stars form via the gravitational collapse of molecular clouds during which time the protostellar object contracts by over seven orders of magnitude. If all the angular momentum present in the natal cloud was conserved during collapse, stars would approach rotational velocities rapid enough to tear themselves apart within just a few Myr. In contrast to this, observations of pre-main sequence rotation rates are relatively slow (∼ 1 − 15 days) indicating that significant quantities of angular momentum must be removed from the star. I use observations of fully convective pre-main sequence stars in two well-studied, nearby regions of star formation (namely the Orion Nebula Cluster and Taurus-Auriga) to determine the removal rate of stellar angular momentum. I find the accretion disc-hosting stars to be rotating at a slower rate and contain less specific angular momentum than the disc-less stars. I interpret this as indicating a period of accretion disc-regulated angular momentum evolution followed by near-constant rotational evolution following disc dispersal. Furthermore, assuming that the age spread inferred from the Hertzsprung-Russell diagram constructed for the star forming region is real, I find that the removal rate of angular momentum during the accretion-disc hosting phase to be more rapid than that expected from simple disc-locking theory whereby contraction occurs at a fixed rotation period. This indicates a more efficient process of angular momentum removal must operate, most likely in the form of an accretion-driven stellar wind or outflow emanating from the star-disc interaction. The initial circumstellar envelope that surrounds a protostellar object during the earliest stages of star formation is rotationally flattened into a disc as the star contracts. An effective viscosity, present within the disc, enables the disc to evolve: mass accretes inwards through the disc and onto the star while momentum migrates outwards, forcing the outer regions of the disc to expand. I used spatially resolved submillimetre detections of the dust and gas components of protoplanetary discs, gathered from the literature, to measure the radial extent of discs around low-mass pre-main sequence stars of ∼ 1−10 Myr and probe their viscous evolution. I find no clear observational evidence for the radial expansion of the dust component. However, I find tentative evidence for the expansion ofthe gas component. This suggests that the evolution of the gas and dust components of protoplanetary discs are likely governed by different astrophysical processes. Observations of jets and outflows emanating from protostars and pre-main sequence stars highlight that it may also be possible to remove angular momentum from the circumstellar material. Using the sample of spatially resolved protoplanetary discs, I find no evidence for angular momentum removal during disc evolution. I also use the spatially resolved debris discs from the Submillimetre Common-User Bolometer Array-2 Observations of Nearby Stars survey to constrain the amount of angular momentum retained within planetary systems. This sample is compared to the protoplanetary disc angular momenta and to the angular momentum contained within pre-stellar cores. I find that significant quantities of angular momentum must be removed during disc formation and disc dispersal. This likely occurs via magnetic braking during the formation of the disc, via the launching of a disc or photo-evaporative wind, and/or via ejection of planetary material following dynamical interactions.