This thesis was written for a Swedish valve manufacturer to find out in what temperature regimes it was possible to replace electroplated hard chromium with autocatalytic electroless nickel-phosphorus. In this work the dry sliding wear properties of electroplated hard chromium and autocatalytic electroless nickel-phosphorus(10% P) were compared. All tests and investigations were done by using available equipment at Karlstads University. The tests were made to find out how the wear of these coatings behaved at different temperatures, how different substrates influence the wear of these coatings and how the roughness of the substrate surface influence the wear properties of these coatings. The method used for the wear tests was block-on-ring with a counterformal contact mode. The tests were executed in room temperature, 300C and 400C; with a normal load of 100N, sliding speed was 150rpm and duration of the tests were 15 minutes. All tests were done in an argon gas atmosphere. The coatings was deposited onto the cylinders with a thickness of 30µm. The different substrates used were an austenitic stainless steel(1.4404) and an austenitic-ferritic(duplex) stainless steel(1.4460). Half of the austenitic cylinders had a machined surface and all the others(including duplex cylinders) were machined and grinded to achieve a smoother surface. The blocks used as countersurface were made out of austenitic-ferritic(duplex) stainless steel(1.4460). Equipment used to investigate the wear tracks were stereo microscopy, profilometer, microhardness tester and scanning electron microscopy(SEM). The coatings were investigated in matter such as wear depth, wear mode, wear mechanism, chemical composition, topography, morphology, cross-section and hardness. The results of this work showed that the nickel coating wear tracks maximal depth were less deep than those of hard chrome, at room temperature. At elevated temperatures the performance varies. The coatings deposited onto cylinders made out of duplex stainless steel performed better than those deposited onto austenitic cylinders. The nickel coating performed better deposited onto the substrates with smooth surface and the chrome coating performed better deposited onto the substrates with rough surface

In my thesis, I focus on the operating system Google Chrome OS, determination of its characteristics, definition of target group of the operating system's users and comparison of available applications with those available for other operating systems. In the theoretical part, historical development of Google is analysed first, followed by the issue of Google Chrome web browser and analyse of the operating system Google Chrome OS. The practical part starts with evaluation of survey on the operating system Google Chrome OS and is followed by multi-criteria analysis of variants comparing various categories of applications available for the operating system Google Chrome OS and other operating systems, in this case represented by the operating system Microsoft Windows 8.1 and distribution of Linux operating system Ubuntu 14.04 LTS.

nÃo hà / A saÃde do trabalhador no Brasil tomou novo rumo com uma nova visÃo, mais ampla e integral do processo saÃde-doenÃa, considerando-se as questÃes relacionadas a acidentes e doenÃas ocupacionais sobre o trabalho. Dentre as vÃrias doenÃas estÃo a Perda Auditiva Induzida pelo RuÃdo (PAIR) e os trabalhadores que sÃo continuamente expostos a compostos quÃmicos em ambientes industriais. Entre estes, figuram os chamados compostos hexavalentes e os compostos formados por cromo trivalente. O objetivo desta pesquisa foi verificar se a exposiÃÃo simultÃnea de ruÃdo e cromo potencializa o aparecimento da perda auditiva ocupacional dos trabalhadores de curtume em Teresina-PI. As caracterÃsticas da populaÃÃo em estudo, sÃo todos os trabalhadores do sexo masculino, divididos em 3 grupos, sendo: Grupo I - exposto a cromo e ruÃdo (n = 9); Grupo II - exposto a ruÃdo (n = 9); Grupo III - controle (n =10) na faixa etÃria de 38,11  5,9 , 30,83  7,4 e 27,40  7,0 anos, respectivamente. Os trabalhadores do Grupo I e II trabalham em mÃdia 9 horas diÃrias e 22,2% do grupo I apresentam problemas cardiovasculares e 16,7% do grupo II alteraÃÃo da pressÃo arterial. Em relaÃÃo ao tempo de trabalho, verifica-se um maior tempo de trabalho para os trabalhadores expostos a cromo e ruÃdo em mÃdia 13 anos, estes desenvolvem suas atividades laborais em sua maioria nos setores de curtimento, classificaÃÃo de peles e Ribeira, sÃo os que estÃo em contato permanente com o cromo (55%), enquanto que os expostos a ruÃdo (grupo II) sÃo os trabalhadores dos setores de acabamento, rebaixamento e lixadeira de couro (83,3%). Quando relacionado à funÃÃo e de acordo com a categoria profissional os que mais se expÃem a ruÃdo e cromo sÃo os auxiliares de produÃÃo, (44,5% exposto a ruÃdo e cromo e 91,5% expostos a ruÃdo). Em relaÃÃo aos EPIs somente (55,6%) de trabalhadores expostos ao cromo e ruÃdo utilizam protetor auricular do tipo plug; e nenhuma proteÃÃo para o cromo. Nos expostos somente a ruÃdo o uso de EPI à de apenas 25%. Sobre sua percepÃÃo quanto a sua prÃpria audiÃÃo, todos os grupos referem-na como boa, apenas 20% dos que responderam do grupo I referiu-se a sua audiÃÃo como ruim. No grupo exposto somente a ruÃdo 8,3% relatam otalgia, enquanto que 100% dos expostos a cromo e ruÃdo fazem esse relato, apresentando significÃncia p< 0,05. Os trabalhadores do Grupo I e II queixam-se de tonturas frequentes (44% e 25%), zumbido (22,2% e 50%) respectivamente. Quanto ao resultado do exame audiomÃtrico, 100% do Grupo Controle e os expostos a RuÃdo apresentaram Limiares Auditivos dentro dos PadrÃes de Normalidade enquanto 22,2% dos expostos a cromo e ruÃdo apresentaram perda auditiva neurossensorial. Quando avaliados os parÃmetros de cromo na urina, ocorreu um aumento significante no valor da dosagem de cromo dos trabalhadores expostos a cromo e ruÃdo p<0,001 (2,76  0,76 ) em relaÃÃo aos expostos somente a ruÃdo p<0,05 (1,62  1,77), quando comparados com o controle. Assim salienta-se a necessidade de investigaÃÃo da perda auditiva em trabalhadores de curtume como estratÃgia de prevenÃÃo, associados a contÃnuos programas educacionais relacionados ao uso correto de equipamentos de proteÃÃo individual tanto na exposiÃÃo a substÃncias quÃmicas como para ruÃdo.

Aufgabenstellung: Aus einem Rohrstück des Materials P91 soll nach der Erarbeitung eines Probenplans zunächst das Gefüge in allen 3 Orientierungen metallographisch charakterisiert werden. Anschließend wird das Material mechanisch - technologisch sowie bruchmechanisch und fraktographisch untersucht. Die daraus erhaltenen Werkstoffkennwerte sollen mit dem Gefüge und dem fraktographischen Befund in Beziehung gesetzt werden.

M.Comm. (Business Management) / Please refer to full text to view abstract

Aufgabenstellung: Aus einem Rohrstück des Materials P91 soll nach der Erarbeitung eines Probenplans zunächst das Gefüge in allen 3 Orientierungen metallographisch charakterisiert werden. Anschließend wird das Material mechanisch - technologisch sowie bruchmechanisch und fraktographisch untersucht. Die daraus erhaltenen Werkstoffkennwerte sollen mit dem Gefüge und dem fraktographischen Befund in Beziehung gesetzt werden.

När man arbetar så blir det lätt att man faller in i rutiner. Dessa rutiner kan göra detsvårt att se att ens uppgifter kan ses som repetitiva. Det är också svårt för någon utom-stående att se dessa repetitiva mönster. Målet med detta arbete är att kunna visa för enanvändare vilka delar av dennes arbete som skulle kunna automatiseras. Detta uppnåsmed hjälp av två verktyg som vi utvecklat; en Chrome-extension som loggar vad enanvändare gör under arbetsdagen, samt ett analysverktyg i Python som analyserar datanfrån extensionen och visar möjliga repetitiva moment.Chrome-extensionen loggar varje gång användaren interagerar med ett element påen hemsida till en händelselogg. Denna händelselogg kan sedan exporteras som enJSON-fil och matas in i ett Python-skript för att analyseras och hitta repetitiva mönsteroch arbetsmoment.Efter att ha testat processen på två testfall kom vi fram till att den inte fungerar heltsom planerat, då extensionen behöver samla in mer data och analysen behöver leta eftermönster som är snarlika, inte bara identiska. Verktyget har potential att användas inomfaktiskt verksamhet men då skulle det krävas en vidareutveckling av både Chrome-extensionen samt analys-skriptet.

Thesis deals with the operating system Google Chrome. First, the system is described (how it works, its user interface). Next there is a characteristic of applications that can be downloaded to the system and how they work. Another part is devoted to security, which consists of several elements. The end of the theoretical part is focused on Chromebooks - devices in which the operating system is sold on the market. The practical part is firstly characterized Dart programming language, which is then used for an application. This application shows not only work with the language, but also the benefits of Google Apps. It also shows compatibility with Windows and compares these two systems. In conclusion are described advantages and disadvantages of Chrome system and summarizes all knowledge arising from this work.

Les alliages fer-chrome présentent des comportements thermodynamiques et cinétiques particuliers liés à leurs propriétés magnétiques. La décomposition de l’alliage par vieillissement thermique a été étudiée dans cette thèse. Pour cela, un modèle cinétique de la décomposition de l’alliage à l’échelle atomique a été développé en modélisant de façon détaillée les propriétés thermodynamiques et de diffusion des espèces chimiques dans l’alliage. L’évolution des propriétés de diffusion des éléments avec la transition ferro-paramagnétique de l’alliage a en particulier été modélisée. Les décompositions simulées par ce modèle ont été comparées à des décompositions expérimentales pour une large gamme de concentrations et de températures. Cette comparaison a montré un bon accord entre les cinétiques simulées et les expériences et a permis de mettre en évidence le rôle central de la transition ferro-paramagnétique dans la cinétique de décomposition des alliages fortement concentrés en chrome. Cette étude a également montré que la diffusion des éléments à l’interface des phases est responsable de la cinétique de décomposition de l’alliage aux temps longs. Une étude de la ségrégation induite par l’irradiation au voisinage des puits de défauts a également été commencée. Pour cela, un modèle de l’évolution de l’alliage sous irradiation contenant un puits de défauts a été développé. Il a été montré, en accord avec la littérature, que pour les cas faiblement concentrés en chrome, l’alliage a tendance à s’enrichir en chrome au voisinage des puits de défauts à basse température et à s’appauvrir en chrome à haute température. / Iron-Chromium alloys have a peculiar thermodynamic and diffusion behavior which is due to their magnetic properties. The alloy decomposition under thermal ageing has been studied in this thesis. An atomistic kinetic model has been performed in this aim in which we have modeled in details the chemical species thermodynamic and diffusion properties. In particular, the evolution of elements diffusion properties with the ferro-paramagnetic transition has been introduced in the model. Simulated decompositions have been compared with experiments for a large range of concentrations and temperatures. A good agreement between simulations and experiments was observed and these comparisons have highlighted the ferro to paramagnetic transition key role in the concentrated alloys kinetic decomposition. This study has also evidenced that the elements diffusion at phases interfaces is responsible for the alloy decomposition kinetic in long lasting. We have also started a study on the alloy radiation induced segregation. For that purpose, atomistic kinetic model has been performed modeling defects migration through a perfect planar sink. It have been shown, I agreement with former studies, that chromium tends to segregate in the vicinity of sinks a low temperatures and deplete at high temperature.

La rectification est un procédé de fabrication permettant d’obtenir des états de surface très fins. Elle est généralement utilisée sur des matériaux très durs pour lesquels les autres procédés d’usinage ne sont pas adaptés. La rectification fait intervenir des mécanismes d’enlèvement de matière complexes encore difficiles à maitriser. Ils se produisent à des échelles microscopiques délicates à mettre en évidence. De plus, la rectification fait intervenir des énergies mécaniques et thermiques conséquentes qui peuvent endommager la pièce à usiner. La compréhension de ces phénomènes est donc nécessaire pour améliorer ce procédé en termes de productivité et de qualité. Dans ces travaux, plusieurs axes de recherche ont été développés aussi bien en étudiant la pièce rectifiée que l’évolution de l’outil abrasif de rectification. Des analyses ont été réalisées sur le revêtement de chrome et le substrat. Elles nous ont permis de détecter les variations de la texture cristallographique, des contraintes superficielles et de la dureté liées au procédé sur le revêtement de chrome, mais également sur le substrat qui peut également être affecté. Les grandeurs mesurées in process (puissance, efforts et température à l’interface meule/pièce) couplées à des simulations par éléments finis nous ont permis de caractériser la propagation du flux de chaleur à travers la pièce rectifiée et les conditions nécessaires pour ne pas l’endommager. L’évolution de la surface abrasive de la meule a fait l’objet d’une étude avancée avec la mise en place d’une mesure indirecte par empreinte, mesurée ensuite à l’aide d’un microscope optique confocal. Une méthode de redressement et de filtrage de la topographie a été développée. A partir de la topographie, la densité de grains et un profil de grain moyen ont été déterminés. Ceux-ci nous ont permis de mieux comprendre les modes d’usure de différentes technologies de meules abrasives. Cette modélisation de la topographie est introduite dans un modèle analytique d’abrasion afin de déterminer les efforts tangentiels de rectification en fonction de l’usure de la meule. Une comparaison des efforts tangentiels aux valeurs mesurées est réalisée pour différentes conditions de rectifications et différentes technologies de meules / The grinding process is a manufacturing method that can obtain extremely precise surface conditions. Most of time, it is used on very hard materials when other machining processes are inefficient. Grinding uses complicated material which removal mechanisms are still hard to control. These mechanisms appear on a microscopic scale and are barely detectable. Moreover, grinding supposes important mechanical and thermal energies that can damage the workpiece. These criteria must be taken into account in order to improve the quality and the productivity of the process. In this work, several researches focus have been developed, both by studying the workpiece and by considering the abrasive tool evolution. Analyses have been realized on the chrome coating as well as on the substrate. It allowed us to detect texture variation, surface stresses and hardness on the chrome coating. Due to the process, the latter as well as the substrate under it can also be affected. Experimental results mixed with a finite elements modeling allowed us to understand the heat flux transfer between the workpiece and the necessary conditions in order not to affect it. The evolution of the wheel’s abrasive surface was a full advanced study part with the setup of an indirect measure by footprint. This footprint was then measured by a confocal microscope. A way to redress and filter the topography was developed and allowed to understand better the different grinding wheel wear patterns. Topographic results and analytic model let us determine tangential grinding forces versus grinding tool wear