Este trabalho analisou o processo de moldagem por injeção de micro elementos ópticos difrativos usinados em insertos de cobre eletrolítico com ferramenta de diamante com ponta única. Quatro tipos de microestruturas características foram selecionados neste estudo, a saber: lente anesférica, lente de Fresnel, grade de difração (blaze grating) e sensor de frente de onda. A análise da fidelidade de replicação foi feita considerando aspectos dimensionais micrométricos e nanométricos para a microestrutura e acabamento. Um perfilometro óptico e microscópio eletrônico de varredura foram utilizados para avaliar os insertos usinados e as características dos replicados. Uma ferramenta de diamante com geometria especial, com meio raio, foi usada para usinar as características de difração. As superfícies usinadas apresentaram baixo acabamento superficial, na faixa de 16 nm Rms. As simulações numéricas foram realizadas para avaliar o desempenho do processo de moldagem por injeção com polimetilmetacrilato (PMMA), e os resultados foram utilizados para orientar a injeção do polímero. Com base na simulações numéricas as temperaturas do molde e pressões de injeção foram variadas entre 85ºC/130°C e 70 bar/130 bar, respectivamente. A influência destes parâmetros no desempenho do processo de replicação foi analisada. A análise quantitativa da replicação foi feita através de um parâmetro denominado grau de replicação que define a relação entre a altura nominal da microestrutura do inserto e à altura da microestrutura na réplica de polímero. A grade de difração e o sensor de frente de onda apresentaram os melhores níveis de replicação: 98% e 99%, respectivamente. Os resultados experimentais mostraram que o processo de moldagem por injeção é uma técnica viável para replicar com alta qualidade microcaracterísticas de elementos ópticos de difração gerados por torneamento com ferramenta de diamante com ponta única. / This work investigated the injection molding process of micro diffractive optical elements machined on electrolytic copper inserts by single point diamond turning. Four types of microstructure features were selected in this study, namely: aspherical lens, Fresnel lens, blaze grating and the wavefront sensor. The replication fidelity was evaluated in terms of dimensional micrometric features found in the microstructure and the surface finish. An optical profiler and scanning electron microscopy were used to assess the machined inserts and the replicated features. A special geometry diamond tool with half radius was used to machine the diffraction features. The machined surfaces presented very low surface finish in the range of 16 nm Rms. Numerical simulations were carried out to evaluate the performance of the injection molding process with polymethylmethacrylate (PMMA), and the results were used to guide the polymer injection. Based on numerical simulations mold temperatures and injection pressures were varied between 85°C/130°C and 70 bar/130 bar, respectively. The influence of these parameters on performance of the replication process was assessed. The quantitative assessement of the replication was made by using a parameter called degree of replication which defines the ratio between the nominal height of the microstructure in the insert and the height of the microstructure in the polymer replica. The blaze grating and the wavefront sensor presented the best degrees of replication: 98% and 99%, respectively. The experimental results showed that injection molding process is a viable technique to replicate high quality micro features of optical diffraction elements generated by single point diamond turning.

Additive manufacturing has developed radical through the years. Sandvik has invested in the area by building a center specific for additive manufacturing. Due to problems with the material- and product properties and high production costs no products have been used with additive manufacturing method. These aspects have improved over the years and therefore the master thesis was made with an objective: to compare two different produced blades with focus on the aspects of material- and product properties and production costs. One of the blades was produced through additive manufacturing (AM) and the other blade was produced in today’s production at Sandvik Coromant in Gimo. If the blade can be produced through AM there is a possibility to lower the production costs and improve the degree of design freedom. The material that will be used is SS2230 (50CrV4) which are used in conventionally produced blades and 1.2709 which are used in AM produced blades.   The investigation consisted of five different tests (flow rate, pressure force, vibration, fatigue and keyhole wear) and a study on production aspects with focus on value stream mapping, investments and production costs. The main objective in the result was to compare each test between the two different produced blades, not to investigate the optimal value. Therefore, was the test designed to have continuity with as small deviation as possible between the tests. This resulted in choosing values which were not optimal for the blades but focused on continuity and deviation.   The coolant channels flow rate improved with 35% on the AM produced blades but pressure force, fatigue and keyhole wear resistance did not deviate much from conventionally produced blades. Fatigue tests were made twice with two different inserts because the result from the first test differentiated too much from the expected results on both blades. Production costs will be higher with AM but on a long-term may an investment improve the degree of design freedom on a product and a possibility to produce towards costumer (just in time). This will need an expensive investment with a bigger perspective on the timeframe. The value of the product may increase but the production costs will increase too.

Este trabalho analisou o processo de moldagem por injeção de micro elementos ópticos difrativos usinados em insertos de cobre eletrolítico com ferramenta de diamante com ponta única. Quatro tipos de microestruturas características foram selecionados neste estudo, a saber: lente anesférica, lente de Fresnel, grade de difração (blaze grating) e sensor de frente de onda. A análise da fidelidade de replicação foi feita considerando aspectos dimensionais micrométricos e nanométricos para a microestrutura e acabamento. Um perfilometro óptico e microscópio eletrônico de varredura foram utilizados para avaliar os insertos usinados e as características dos replicados. Uma ferramenta de diamante com geometria especial, com meio raio, foi usada para usinar as características de difração. As superfícies usinadas apresentaram baixo acabamento superficial, na faixa de 16 nm Rms. As simulações numéricas foram realizadas para avaliar o desempenho do processo de moldagem por injeção com polimetilmetacrilato (PMMA), e os resultados foram utilizados para orientar a injeção do polímero. Com base na simulações numéricas as temperaturas do molde e pressões de injeção foram variadas entre 85ºC/130°C e 70 bar/130 bar, respectivamente. A influência destes parâmetros no desempenho do processo de replicação foi analisada. A análise quantitativa da replicação foi feita através de um parâmetro denominado grau de replicação que define a relação entre a altura nominal da microestrutura do inserto e à altura da microestrutura na réplica de polímero. A grade de difração e o sensor de frente de onda apresentaram os melhores níveis de replicação: 98% e 99%, respectivamente. Os resultados experimentais mostraram que o processo de moldagem por injeção é uma técnica viável para replicar com alta qualidade microcaracterísticas de elementos ópticos de difração gerados por torneamento com ferramenta de diamante com ponta única. / This work investigated the injection molding process of micro diffractive optical elements machined on electrolytic copper inserts by single point diamond turning. Four types of microstructure features were selected in this study, namely: aspherical lens, Fresnel lens, blaze grating and the wavefront sensor. The replication fidelity was evaluated in terms of dimensional micrometric features found in the microstructure and the surface finish. An optical profiler and scanning electron microscopy were used to assess the machined inserts and the replicated features. A special geometry diamond tool with half radius was used to machine the diffraction features. The machined surfaces presented very low surface finish in the range of 16 nm Rms. Numerical simulations were carried out to evaluate the performance of the injection molding process with polymethylmethacrylate (PMMA), and the results were used to guide the polymer injection. Based on numerical simulations mold temperatures and injection pressures were varied between 85°C/130°C and 70 bar/130 bar, respectively. The influence of these parameters on performance of the replication process was assessed. The quantitative assessement of the replication was made by using a parameter called degree of replication which defines the ratio between the nominal height of the microstructure in the insert and the height of the microstructure in the polymer replica. The blaze grating and the wavefront sensor presented the best degrees of replication: 98% and 99%, respectively. The experimental results showed that injection molding process is a viable technique to replicate high quality micro features of optical diffraction elements generated by single point diamond turning.

Nos últimos anos, avanços consideráveis foram alcançados no estudo da usinabilidade de materiais frágeis tais como cristais semicondutores, vidros ópticos, cerâmicas, etc. em função da demanda por processos mais rápidos de fabricação de superfícies com formas complexas para aplicações nos campos da óptica e eletrônica. A ductilidade apresentada por monocristais de silício durante a usinagem tem sido explicada através das Teorias de Mecânica de Fratura. Recentemente, algumas teorias novas foram apresentadas para justificar esta ductilidade. Foi proposto que a ductilidade de monocristais semicondutores seria provavelmente o resultado final de uma transformação de fase induzida por pressão/tensão durante o corte. Neste trabalho, a diferença entre os modos dúctil e frágil no Torneamento com Ferramenta de Ponta Única de superfícies de silício monocristalino foram investigadas através da técnica de espalhamento Raman. Nas condições que proporcionam o regime dúctil, existem sempre uma amorfização superficial nas amostras, denunciadas através da ativação de uma banda óptica Raman mais larga em 470 cm-1. Esta fase amorfa pode ser considerada resultante da transição de fase a qual o silício pode ter sofrido. Por outro lado, para as condições onde o modo frágil é predominante, somente um pico óptico agudo de fonon em 521.6 cm-1 está presente no espectro Raman. Baseado nas medições que determinados parâmetros de corte, tais como a profundidade de corte e a espessura crítica do cavaco, apresentaram este estudo propõe que o regime dúctil não deve possuir uma faixa definida e fixa de valores para os parâmetros críticos mas, ao invés disso, estes seriam dependentes da extensão da camada transformada induzida por pressão/tensão gerada pela interação entre a ponta/aresta da ferramenta de corte com a peça durante a usinagem. Esta proposta se baseia na comparação entre os valores obtidos e os medidos por outros autores que mostram que a extensão da fase amorfa observada após processos de deformação mecânica (p.e., indentação, riscamento, polimento, nanoretificação e torneamento com ferramenta de ponta única de diamante) encontram-se na mesma faixa de valores encontrados para os parâmetros críticos (100-200 nm). Finalmente, foi demonstrado, através de observações da topografia de ambos, cavacos e superfícies geradas, realizadas com MEV e MFA, que este tipo de análise pode oferecer explicações significativas sobre os mecanismos de remoção de material em ação durante a usinagem e também sobre o estado microscópicos da ferramenta de diamante. / In recent years, considerable progress has been made on the study of the machinability of fragile materials such as semiconductors crystals, optical glasses, ceramics, etc., because of the demand for faster fabrication processes of complex surface shapes for optoelectronic applications. The ductility presented by single crystal silicon during machining has been explained by fracture mechanics theories. Recently, some new theories have been presented in order to give another justify to this ductility. It was proposed that semiconductors single crystal ductility is likely the end result of a pressure/stress induced phase transformation during cutting. In this work, the difference between ductile and brittle mode single-point diamond turning on the surface of machined silicon samples were investigated using Raman scattering. In the ductile mode conditions of machining, there are always an amorphization of the surface samples, denounced by the activation of the broad Raman optical band at 470 cm-1. This amorphous phase can be considered resulted from the phase transiton which silicon might have suffered. Contrary to the findings, in the brittle mode conditions, only the sharp optical phonon peak at 521.6 cm-1 is present in Raman spectra. Based on the observation that certain cutting parameters such as cutting depth and critical chip thickness, e.g., the point where ductile-to-brittle transition occurs, somehow presents values in the same range (100-200 nm) that the amorphous phase layer depth extension after mechanical deformation. (p.e., indentation, scratching, polishing, nanogrinding and single point diamond turning) observed in the literature, it is propposed that the ductile regime has not a definite range of values for the critical parameters but instead, it is dependent of the extension of the phase transformed layer induced by pressure/stress generated by the tool tip/edge interaction with workpiece during machining. Finally, it is shown that observation of topography and morphology of chip and the surface generated through SEM and AFM can offer very significant explanation of the material removal mechanisms in action during the current machining cut and diamond tool state.

Este trabalho teve como objetivo o estudo experimental de lubrificação e resfriamento no torneamento duro de uma superfície funcional em componentes de grande porte, com aplicação no chão de fábrica. Foram comparadas as técnicas de mínima quantidade de lubrificante e resfriamento abundante, utilizando o método de resposta de superfície. O planejamento tridimensional utilizado foi de dois níveis, adicionado de pontos axiais, ponto central e de réplica. Foram variados a velocidade periférica da peça, o avanço da ferramenta de usinagem e a profundidade de usinagem. Após a execução do experimento, a integridade da superfície foi analisada pela medição da tensão residual, da espessura de possíveis modificações microestruturais e pela medição dos parâmetros estatísticos Sa, Sq e Sz. As medidas foram então ajustadas em modelos matemáticos, otimizadas e por fim comparadas. A análise dos resultados sinalizou que os modelos ajustados para ambos os métodos foram capazes de explicar satisfatoriamente o comportamento das variáveis de resposta. Ainda, a partir da função desirability, foi possível estimar valores ótimos com qualidade equivalente entre os métodos. Tanto para o emprego com mínimas quantidades quanto para resfriamento abundante foram registradas tensões circunferenciais altamente compressivas. Nas condições ótimas, quando empregadas mínimas quantidades de lubrificante, a superfície apresentou valores de tensões residuais 37% maiores em comparação ao obtido quando empregado o resfriamento abundante. Ambos os métodos produziram tanto superfícies livres de modificações microestruturais significativas, como também superfícies com modificações microstruturais significativas. Porém, quando detectadas, as modificações se mostraram muito reduzidas, com espessura de até 2,35 &#956m. Nas condições ótimas, quando empregado mínimas quantidades de lubrificante, a espessura da modificação foi 74% menor em comparação ao obtido quando empregado o resfriamento abundante. Os parâmetros estatísticos sugeriram alguma vantagem da aplicação de mínimas quantidades de lubrificante. Nas condições ótimas, a aplicação MQL apresentou melhor rugosidade Sa, em 47%, e Sz, em 11%. Porém, o desvio-padrão Sq da superfície apresentou valor 12% maior ao resfriamento abundante. / This work aimed to conduct a study of cooling and lubrication in hard turning of functional surface of large components. It was compared the performance of minimum quantity lubrication and abundant cooling through the application of response surface methodology. The activities were developed in shop floor application. It was designed a three-dimensional experiment with two levels, added by axial points, center point and one center replicate. The input variables were the peripheral velocity of the workpiece, the feed of the cutting tool and the depth of cut of machining. After the process were analyzed the surface integrity through the circumferential residual stress, possibly microstructure modified layers and statistical parameters such Sa, Sq and Sz. Then, the measurements were adjusted in mathematical models, optimized and compared. The analysis of the results indicated that the adjusted models for both methods were capable of explaining satisfactorily the behavior of the response variables. Also, the use of the desirability function allowed to predict optimal values with equivalent quality between the methods. The minimal quantities, as well the abundant cooling, produced circumferential residual stresses highly compressive. On optimal conditions, the MQL presented residual stresses 37% lower the abundant cooling. Both methods produced surfaces free of significant altered layers as well surface containing significant surface altered layer. However, when detected, the altered surface layer was very thin, with thickness up to 2,35 &#956m. On optimal conditions, the MQL altered layer was 74% lower the abundant cooling. The statistical parameters indicated some advantage on the application of MQL. On optimal conditions, the minimal quantities presented better Sa roughness in 47%, and Sz, in 11%. However, the standard deviation Sq of the surface presented a value 12% higher the abundant cooling.

Apesar dos elevados teores de matéria orgânica nos resíduos domiciliares e da implantação da compostagem para os resíduos sólidos orgânicos ser prevista pela Política Nacional de Resíduos Sólidos (Lei n° 12.305/10), a adoção da prática como forma de tratamento ainda apresenta ações incipientes no país. Este trabalho teve como proposta a coleta seletiva da fração orgânica dos resíduos sólidos urbanos (FORSU) produzida em 19 estabelecimentos comerciais de São Carlos para a realização da compostagem e vermicompostagem. A primeira etapa do trabalho consistiu na verificação da adaptação dos proprietários dos estabelecimentos em relação ao sistema de segregação proposto e na avaliação da percepção dos mesmos em relação à separação dos resíduos orgânicos e da compostagem, sendo esta análise realizada através da aplicação de questionários. Na segunda etapa, foi realizada a compostagem em quatro leiras cilíndricas de alambrado de 1,2 m de diâmetro e 1 m de altura. Testou-se os seguintes tratamentos em cada leira: trituração e revolvimento, não trituração e revolvimento, não trituração e não revolvimento (controle) e não trituração e não revolvimento com tubos de PVC. Verificou-se, através do monitoramento dos parâmetros físicos, químicos e microbiológicos e de análises estatísticas, as diferenças e similaridades entre os tratamentos. A terceira etapa iniciou-se após a estabilização dos compostos. Foram inoculadas 500 minhocas da espécie Eisenia foetida em uma quantia entre 20-25 kg de composto retirado das leiras revolvidas e os mesmos parâmetros da etapa anterior foram monitorados na vermicompostagem. Os resultados encontrados na etapa 1 indicaram que: os estabelecimentos realizaram a correta segregação dos resíduos, mostrando-se bem adaptados; quase a metade dos entrevistados desconheciam a técnica de compostagem; e, embora a maioria realizasse a separação da FORSU, a mesma era coletada de forma não diferenciada e encaminhada diretamente ao aterro. Na etapa 2, constatou-se que: o revolvimento influenciou na manutenção da temperatura termofílica por períodos mais prolongados, na correção da umidade, nos valores de pH , nitrogênio, relação C/N, CRA, metais, macro e micro nutrientes e granulometria; em relação à trituração, com exceção da granulometria, os demais parâmetros monitorados foram similares a leira não triturada, demostrando pouca influência de sua adoção no processo de compostagem; na leira composta por tubos de PVC, os registros de temperatura foram menores que as demais, de forma que o dispositivo ocasionou um resfriamento excessivo. Concluiu-se que somente a etapa 2 foi suficiente para o atingimento dos limites legais estabelecidos para os fertilizantes orgânicos, sendo os benefícios da adoção da vermicompostagem na etapa 3 relacionados aos incrementos das propriedades agronômicas de fertilidade de solo. / Despite the presence of high levels of organic matter in household wastes and the implementation of composting for organic wastes provided by the National Policy on Solid Waste (Law No. 12,305/10), the composting practice as a treatment is still incipient in Brazil. This study aimed at the selective collection of the organic fraction of municipal solid wastes (OFMSW) produced in 19 establishments in São Carlos city for use in composting and vermicomposting techniques. The first stage of the study consisted in an investigation on the adaptation to the segregation system proposed and evaluation of the owners\' perceptions regarding the separation of organic waste and composting through questionnaires. The second stage was devoted to the composting. The collected waste was deposited onto four cylindrical piles of 1.2 m diameter and 1 m height. The treatments evaluated in each pile were trituration and turning, no trituration and turning, no trituration and no turning (control), and no trituration and no turning of PVC pipes. The monitoring and statistical analysis of the physical, chemical and microbiological parameters revealed differences and similarities in each treatment. The third stage started after the stabilization of the compost. Five hundred earthworms of Eisenia foetida specie were inoculated in 20-25 kg of compost taken from two piles and the same parameters of the previous step were monitored. In step 2, the turning influenced the maintenance of the thermophilic stage for longer periods, humidity correction, values of pH, nitrogen, C/N relation, WRC, metals, micro and macronutrient and particle size. Except for the particle size, trituration exerted little influence on the parameters. The lowest temperatures were recorded in a pile composed of PVC pipes. It can be concluded that only the second step was sufficient for the achievement of legal limits for organic fertilizers and the benefits of vermicomposting as a post treatment technique (step 3) are related to the increase in the agronomic properties of soil fertility.

<p>The present thesis examines the possible reasons social workers have for entering and eventually graduating from the Social Work Department in Iraklio, Greece. It is a three-phase study, consisting of three distinct but related research parts; each research part is built upon knowledge, issues and questions derived from the preceding part.</p><p>My background in sociology influenced the choice of theoretical perspectives; I was not interested in investigating students’ choice from a psychologically-based perspective. Bourdieu (e.g. 1977; 1987) and the work of others who have drawn on and developed his work (e.g. Hodkinson & Sparkes, 1997; Reay, 1998a) constituted a theoretical framework. In addition, theoretical perspectives which recognise the interplay between individual and structural factors (e.g. Kasimati, 1991) also proved useful. In this work both quantitative and qualitative approaches (grounded theory, narrative analysis) were employed.</p><p>The findings contradict views that stress the degree of free choice people have about work; it is clear that external structural factors limit or contribute to the shaping of this choice. This is not to say, however, that the findings stress the determining influence of solely external factors on students’ choice. Students in this thesis describe actively making decisions; they are players in the field of education. They enter the field with unequal amounts of capital (economic, cultural); thus, although in theory everyone is free to play, not everyone is equal. To the extent that they have different social backgrounds (gender, class), their classed-and-gendered habitus differs as well. In the process of students’ educational choice, their habitus along with the particular educational system (with all its opportunities and restrictions) influence students’ horizons for action, their perceptions of what is available and appropriate for them. The high value placed on higher education (educational fetishism) is another factor influencing students’ horizons for action. In the context of their horizons for action, students employ a variety of strategies in order to enter higher education (e.g. the way they prepare for the exams, their ranking of Schools in preference order etc). The outcome of these strategies is their admission to the Social Work Department, which may have been intended or unintended. After having entered Social Work, additional factors influence students’ educational choice; experiences within the School (e.g. practice tutorials) contribute to their attitude towards social work and their studies, thus to their decision to graduate from the Social Work Department. Students’ decision-making process is made up of patterns of routine experience interspersed with turning points.</p>

<p>In recent years, there has been a great interest towards the higher order numerical methods for singularly perturbed problems. As compared to their lower order counterparts, they provide better accuracy with fewer mesh points. Construction and/or implementation of direct higher order methods is usually very complicated. Thus a natural choice is to use some convergence acceleration techniques, e.g., Richardson extrapolation, defect correction, etc. In this thesis, we will consider various classes of problems described by singularly perturbed ordinary and partial differential equations. For these problems, we design some novel numerical methods and attempt to increase their accuracy as well as the order of convergence. We also do the same for existing numerical methods in some instances. We &macr / nd that, even though the Richardson extrapolation technique always improves the accuracy, it does not perform equally well when applied to different methods for certain classes of problems. Moreover, while in some cases it improves the order of convergence, in other cases it does not. These issues are discussed in this thesis for linear and nonlinear singularly perturbed ODEs as well as PDEs. Extrapolation techniques are analyzed thoroughly in all the cases, whereas the limitations of the defect correction approach for certain problems is indicated at the end of the thesis</p>

The present thesis examines the possible reasons social workers have for entering and eventually graduating from the Social Work Department in Iraklio, Greece. It is a three-phase study, consisting of three distinct but related research parts; each research part is built upon knowledge, issues and questions derived from the preceding part. My background in sociology influenced the choice of theoretical perspectives; I was not interested in investigating students’ choice from a psychologically-based perspective. Bourdieu (e.g. 1977; 1987) and the work of others who have drawn on and developed his work (e.g. Hodkinson &amp; Sparkes, 1997; Reay, 1998a) constituted a theoretical framework. In addition, theoretical perspectives which recognise the interplay between individual and structural factors (e.g. Kasimati, 1991) also proved useful. In this work both quantitative and qualitative approaches (grounded theory, narrative analysis) were employed. The findings contradict views that stress the degree of free choice people have about work; it is clear that external structural factors limit or contribute to the shaping of this choice. This is not to say, however, that the findings stress the determining influence of solely external factors on students’ choice. Students in this thesis describe actively making decisions; they are players in the field of education. They enter the field with unequal amounts of capital (economic, cultural); thus, although in theory everyone is free to play, not everyone is equal. To the extent that they have different social backgrounds (gender, class), their classed-and-gendered habitus differs as well. In the process of students’ educational choice, their habitus along with the particular educational system (with all its opportunities and restrictions) influence students’ horizons for action, their perceptions of what is available and appropriate for them. The high value placed on higher education (educational fetishism) is another factor influencing students’ horizons for action. In the context of their horizons for action, students employ a variety of strategies in order to enter higher education (e.g. the way they prepare for the exams, their ranking of Schools in preference order etc). The outcome of these strategies is their admission to the Social Work Department, which may have been intended or unintended. After having entered Social Work, additional factors influence students’ educational choice; experiences within the School (e.g. practice tutorials) contribute to their attitude towards social work and their studies, thus to their decision to graduate from the Social Work Department. Students’ decision-making process is made up of patterns of routine experience interspersed with turning points.

The aim of this study has been to investigate children and adolescent development in ”The turning point” children´s and adolescent program in Kristianstad. We also wanted to find out the support group leaders experiences concerning the children´s and the adolescents development in programs and how they apprehended their role as a support group leader. Our intension was also to study how the adolescent and the children considered their own development in the program. To carry through this study, we used two types of qualitative methods i.e. qualitative interviews with the support group leaders who used the ”Turning point”  method in their work with the children’s and adolescents groups. We also used qualitative content analysis on the children’s and the adolescents written answers in their evaluation forms. The support group leaders and the adolescents described a positive development through the programs. Both parts states that this development has been noticed by an increased openness about the abuse in the family. Other results was that the children and the adolescent answered that they had realized that they were not alone in their situation, had been helped by the programs, felt happier and had come to realize that they had an identity of their own.