Made available in DSpace on 2014-10-09T12:28:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:01Z (GMT). No. of bitstreams: 0 / Um dos mais críticos problemas encontrados na união de materiais distintos é a formação de tensões residuais, que ocorre principalmente pelo fato desses materiais possuírem coeficientes de expansão térmica e condutividades térmicas diferentes. Neste trabalho foi estudada a técnica de soldagem laser entre o aço carbono AISI 1010 e o aço inoxidável AISI 304. Os materiais foram unidos por solda autógena de topo com um laser de Nd:YAG contínuo. O principal objetivo do estudo foi a identificação da influência dos parâmetros de soldagem, pela análise das tensões residuais na zona termicamente afetada (ZTA). Foi executado um planejamento fatorial de três fatores a dois níveis com uma réplica, em que foram variadas a potência, a velocidade de soldagem e a posição focal do feixe laser. Na superfície da amostra foram realizadas medidas de tensão residual pela técnica de difração de raios X, para estudar sua variação em função dos parâmetros investigados. O método do furo cego foi também utilizado para avaliar a tensão residual ao longo da profundidade das amostras até a profundidade de 1 mm. Além das medidas de tensão residual, os cordões de solda foram avaliados por microscopia óptica e eletrônica de varredura (MEV), que tiveram como objetivos determinar a geometria do cordão e mudanças na microestrutura, também foram feitas medidas de microdureza Vickers para se avaliar a extensão da ZTA. Para se avaliar as propriedades mecânicas da união foram realizados ensaios de tração e fadiga. O software MINITAB 15 foi utilizado para a análise das tensões residuais nas diferentes profundidades da ZTA obtidas pelo método do furo cego. Foi utilizada também a regressão estatística baseada nas diferentes influências da entrada e combinação dos fatores na tensão residual geradas nessa união. Os resultados indicam que o desenvolvimento de modelos pode prever as respostas satisfatoriamente e fornecer aos usuários um guia para definir os melhores parâmetros de união. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Le perçage est un procédé de fabrication répandu dans le milieu industriel. Le secteur aéronautique a recours à ce procédé pour usiner de nombreuses pièces. Les chambres de combustions en sont un exemple. Exposées à des cycles thermiques sévères, elles sont percées d’une multitude de trous de refroidissement. Chez Safran Helicopter Engines, motoriste spécialisé dans la conception de turbines à gaz pour hélicoptères, ce perçage est réalisé à l’aide d’un procédé d’usinage unique : le perçage par percussion laser à la volée. Ce procédé phare leur permet de réaliser des milliers de trous inclinés dans des tôles en matériaux réfractaires. Safran Helicopter Engines cherche à maintenir son avance dans la production de turbines en s’appuyant sur les innovations constantes du procédé de perçage. Ce travail de thèse s’est articule autour du développement d’un nouveau procédé de perçage laser. De manière à définir un procédé fiable et efficace, plusieurs stratégies de perçage sont étudiées via les possibilités offertes par un laser à fibre milliseconde de haute puissance. Les résultats obtenus laissent entrevoir des perspectives intéressantes en termes d’augmentation de cadence de production à qualité d’usinage équivalente. L’amélioration des performances a été démontrée expérimentalement sur un banc d’essais représentatif des machines de production. Des trous de 400 μm de diamètre incliné à 60o ont pu être réalisés avec un cycle de perçage raccourci au minimum d’un facteur 2. Cette thèse présente également des éléments de compréhension des phénomènes de formation d’un trou. Pour cela, une modélisation des processus thermo hydrodynamiques impliqués dans le procédé de perçage laser a été développée. Ce modèle basé sur une approche par éléments finis repose sur l’étude thermique au cours de l’interaction entre le faisceau laser et la matière. Une partie du modèle inclut les phénomènes de propagation du faisceau dans la cavité en cours de formation afin de traduire de manière plus réaliste le dépôt d’énergie. / Drilling is a well-known manufacturing process. The aeronautic industry uses this process to machine a lot of elements. Among them, we can mention turbine blades, fuel injectors, combustion chambers. The latter are exposed to serious thermal stresses. To limit their impacts, combustion chambers are drilled with multiples cooling holes. At Safran Helicopter Engines, engines manufacturer specialized in engines design for helicopters, drilling is performed with a unique machining process : on the fly laser percussion drilling. This flagship process allows drilling thousands of tilted holes on refractory materials. Safran Helicopter Engines seeks to preserve its leading position in turbo engines manufacturing by looking for steady innovative drilling process. This thesis is structured around the development of a new laser drilling process. To define a reliable and efficient process, several drilling strategies were studied through the possibilities offered by a high-power millisecond fiber laser. The presented results allow catching a glimpse of the possibilities of production improvement. The performance enhancement was established through experimentation with a test bench. Holes of 400 μm diameter with an angle of 60o were drilled with a reduced processing time thanks to this new drilling process. In this thesis, we also propose a theoretical approach describing the hole formation. A mathematical model, accounting for all the physical process taking place during the drilling process is introduced. This model is based on finite elements method and considers the laser beam propagation within the drilled holes by solving Maxwell equations

This study evaluates what would be the consequences of a wide implementation of large-scale cash transfer programming in humanitarian aid. The aspects that will be assessed here is the rationale for as well as criticism against the proposed implementation. The study also analysed what implications such a reform would have to key stakeholders in the humanitarian system. The theoretical framework employed for this study consists of two separate sections. The first section presents the available evidence on large-scale cash transfer programming (LSCTP) in terms of efficiency, effectiveness, and accountability to affected populations (AAP). For the second section, a review was conducted on previous studies relating to key stakeholders and how they would be affected by the aforementioned reform. The stakeholders analysed include donors, affected governments, operational humanitarian organisations (NGOs and UN agencies), affected populations, and the private sector. For the study, eight interviews were conducted with key informants, which was complemented by secondary data. The study found that the rationale for donors to implement LSCTP on a wide scale is strong, both from an efficiency, effectiveness, and AAP perspective, although the cost- efficiency aspect does require some attention. With regard to the stakeholders analysed, donors, along with affected populations, affected governments and the private sector, are all expected to benefit from a wide implementation of LSCTP, whereas the reform is expected to be disadvantageous to NGOs and UN agencies.

The purpose of this study was to explore the potential connection between emotional awareness and resilience in a young child affected by HIV/AIDS. The study forms part of a broad research project, the Kgolo-Mmogo project, involving a multidisciplinary team of researchers from the University of Pretoria, South Africa and Yale University in the United States of America. The Kgolo-Mmogo project aims to investigate the adaptive functioning of children affected by HIV/AIDS, whilst potentially enhancing resilience. The project involves an assessment of the participating children, which is followed by a structured intervention and post assessment. The conceptual framework for my study was based on existing literature relating to early childhood development, emotional development, as well as children affected by HIV/AIDS and resilience. I followed a qualitative approach, anchored in the interpretivist paradigm. I utilised an instrumental case study research design and conveniently selected the participants, who were involved in the broader Kgolo- Mmogo project at the onset of my study. One five year old girl, her mother and the care workers who facilitated the intervention, participated in my study. I observed eleven intervention sessions, as well as the pre- and post assessment. In addition to observation, documented in the form of field notes, photographs and a research journal, I employed conversational interviews with the care workers, for data collection and member-checking purposes. I also conducted two semi-structured interviews with the mother of the participant. Three main themes emerged subsequent to thematic data analysis. The first theme relates to developmentally appropriate skills that remained constant throughout my study, with the sub-themes associated with the cognitive, emotional and social domain of development. The second theme concerns accelerated emotional functioning in certain areas of development, with the sub-themes being an increased frequency in referring to feelings, and an increased differentiation when referring to feelings and desires. The last theme entails the enhancement of social skills, with the sub-themes relating to the formation of trusting relationships and enhanced communication about experiences. Based on the findings I obtained, I can conclude that the Kgolo-Mmogo intervention seemingly provided some learning opportunities to foster emotional resilience in a young, vulnerable child. Copyright / Dissertation (MEd)--University of Pretoria, 2010. / Educational Psychology / unrestricted

Kosovo is a disputed territory, in conflict with Serbia, the country it declared independence from in 1999. The two states share water resource, in the form of the Ibër river. Kosovo is facing issues of water scarcity and the water it has access to is heavily polluted with untreated wastewater metallurgy waste.Kosovo does not only have poor relations with Serbia, there are also conflict within Kosovo with communities of both Kosovo Albanian majority and Serb majority. These communities have shown different willingness to cooperate over the water management of the Ibër river basin. Cooperating over shared water resources have in other cases been used as a way to improve on relations in conflict affected societies, through environmental peacemaking. In this case study, the environmental and socio-political conditions for environmental peacemaking is investigated through interviews of municipal and regional stakeholders, involved in the management of the Ibër river basin. Interviews were conducted with two municipal employees and one representative from the regional river basin authority in Kosovo. These interviews were complemented with a comprehensive literature review. The findings were analysed, using a conceptual framework developed to analyse and compare different cases of environmental peacemaking. The conceptual framework consists of six elements: resource scarcity, interdependence, lack of environmental sustainability, mutual interests, shared values, and power (a)symmetries. External actions and interests was also included as an element to reveal in what way external actors can intervene and assist in improving relations through environmental peacemaking initiatives. The analysis concluded that the Ibër river basin is in a need of transboundary management to improve on the water quality in a more effective and efficient way. The resource scarcity that is currently facing the stakeholders could be used as a cooperative trigger between the different actors. And while there is a lot of complexity to within the socio-political conditions, the interviewees express the need and interest for increased cooperation. This indicates that increased collaboration could be possible, but most likely there would be a need for external interventions to create an ongoing dialogue, that in turn can build trust between the conflicting parties. / <p>Remote presentation on Teams</p>

The diploma thesis is dealing with the repair procedure of the cracked ram of the press – machine parts made from gray cast iron by casting. The ram is a part of the repaired forming press LET 160. The presented work contains an overview and analysis of the technologies of repair of cast iron by welding. On the basis of the theoretical part is designed the procedure of repairing. The aim of the experimental tests is selecting the most suitable additional materiál and verifying the proposed welding process. The welding method was selected by a low preheating manual metal arc. All the pWPS were prepared for the welding of all test specimens. Experimental samples were subjected to visual, macroscopic, microscopic analysis and hardness measurement. Based on the results of the experiments was suggested a welding repair procedure with a pWPS.

VACULA Jakub: Optimization of plasma cutting parameters Diploma thesis of the attendance engineer´s study – Mechanical Engineering, specialization Machinery Technology. Academic year 2008/2009. Faculty of Mechanical Engineering of University of Technology in Brno, Institute of the Manufacturing Technology. The Diploma thesis is concerned with the thermal division of a material, concretely by the plasma cutting. It monitors the operational parameters influence of this process to the result quality of cut and the purpose is to optimize these parameters from the qualitative standpoint. The experiment was executed at the plasma cutting equipment Fine Focus 800 of the company KJELLBERG with the utilization of the material S 690 QL. On the base of the literary study of the thermal division of the materials problems it was also described the comparison of the plasma cutting with the method of the division of materials by the oxygen, both from the point of view of the quality, and from the economical point of view.

Supracrystals are highly symmetrical ordered superstructures built up from nanoparticles via self-assembly. While the NP assembly has been intensively investigated, the formation mechanism is still not understood. To shed some light onto the formation mechanism, we are using one of the most common supracrystal morphologies, the trigonal structures, as a model system to investigate the formation process in solution. To explain the formation of the trigonal structures and determining the size of the supracrystal seeds formed in solution, we introduce the concept of substrate-affected growth. Furthermore, we show the influence of the NP concentration on the seed size and extend our investigations from Ag towards Au. 1.

For the past years, there has been an absence of economic crisis on a global level. The unexpected COVID-19 pandemic caused by the SARS-CoV-2 virus led to a significant disruption in economies across the globe, followed by a decrease in economic activity. The decline in economic activity caused market shocks which eventually increased unemployment. This paper aims to analyse unemployment between the years 2018 to 2021 to measure pre- and post-pandemic unemployment rate among Swedish municipalities. The research question is, was the COVID-19 affected significantly related to an increase in unemployment rates across the 290 municipalities in Sweden? Data collection is from several agencies, including the Swedish Public Employment Service (Arbetsförmedlingen), The Public Health Agency of Sweden (Folkhälsomyndigheten), and Statistic Sweden (SCB). The regression model used to analyse the variables are series of fixed effects regression. The aim of this paper is to contribute to the understanding of the pandemic and economic downturn. By examining variables such as COVID-19 affected, immigrants, education, and disposable income in municipalities, this paper was able to conclude that COVID-19 affected are significantly related to unemployment increase in all 290 municipalities.

Recent research following mass shooting events has examined those individuals directly affected by the violence and the impact of the shooting on the whole community. This chapter reviews literature regarding the prevalence of adjustment difficulties among individuals in mass‐shooting‐ affected communities. Emerging research supports that a number of individuals with less severe or even no direct exposure to a mass shooting event may experience adjustment difficulties, including anxiety, depression, and posttraumatic stress disorder (PTSD) symptoms, and, further, that chronic adjustment difficulties can develop. The chapter discusses predictors of adjustment difficulties following mass shootings including the role of preshooting vulnerability, shooting‐related exposure and loss, and postshooting experiences. It considers the possibility that mass shooting events may represent opportunities for positive changes in individuals’ functioning. Finally, the chapter explores research regarding how the community itself may be altered by a mass shooting including changes in community solidarity, identity, and sense of safety within the community.