Orientador: Vicente Afonso Ventrella / Resumo: Dentre os diversos aços ferramenta disponíveis atualmente, encontra-se o aço VP 100, aço ferramenta de estrutura bainítica empregado no setor de fabricação de moldes e matrizes. A literatura traz diversos estudos acerca desse aço frente à processos de usinagem. Entretanto, poucos estudos tratam do comportamento desse aço frente a utilização, direta ou indireta, de processos de soldagem. Desse modo, esse trabalho analisou a influência na estrutura e, nas propriedades mecânicas (dureza e taxa de desgaste) superficiais, do aço VP 100 quando submetido a um processo de tratamento térmico superficial. O processo de tratamento térmico superficial foi realizado através da execução de sucessivos cordões de solda, autógenos, na superfície do material, por meio de um sistema de laser de estado sólido Nd:YAG na condição pulsado. O aço VP 100 foi inicialmente investigado quanto a presença de isotropia em sua estrutura, visando excluir a direção adotada para tratamento térmico como fator influenciador nos resultados. Com uma estrutura visualmente semelhante em todas as direções e, com valores de dureza médios muito próximos entre direções, a direção adotada foi excluída como fator de influência no processo. Em seguida, realizou-se cordões de solda, autógenos, em seis condições distintas (SG, AR, N, N1, N2 e N3), analisados posteriormente através de ensaios de microdureza Vickers, para determinação da melhor condição para execução do tratamento térmico. As condições N1, N2 e N3 (todas com u... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among the steels currently available, is steel VP 100, a tool steel used in the mold and matrix manufacturing sector. There are many research on the machining process forward in this steel. However, few studies deal with work from this steel versus a direct or indirect use of welding processes. In this way, this work analyzed the influence on the structure and, under the mechanical conditions (hardness and wear rate), of the VP 100 steel when subjected to a superficial thermal treatment process. The surface heat treatment process was performed through the execution of successive weld beads, autogenous, on the surface of the material by means of a Nd: YAG solid state laser system in pulsed condition. The VP 100 steel was first investigated for the presence of isotropy in its structure, aiming the analysis if the direction took adopted for the heat treatment as an influencing factor in the results. With a visually similar structure in all directions and, with the average hardness values very close between the directions, the adopted direction was excluded as a factor of influence in the process. In the next step, weld beads, autogenous, were produced in six different condition (SG, AR, N1, N2 and N3), posterior analyzed by means of Vickers microhardness tests to determine the best condition for heat treatment. The N1, N2 and N3 conditions (all using nitrogen gas) presented the best hardness results (superficially and in the depth range of 0.30 mm), being chosen for the executio... (Complete abstract click electronic access below) / Doutor

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No. of bitstreams: 1 crespo_gs_dr_ilha.pdf: 4967768 bytes, checksum: c8e5785db6eaf0a8ac2b750452764960 (MD5) Previous issue date: 2018-08-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Dentre os diversos aços ferramenta disponíveis atualmente, encontra-se o aço VP 100, aço ferramenta de estrutura bainítica empregado no setor de fabricação de moldes e matrizes. A literatura traz diversos estudos acerca desse aço frente à processos de usinagem. Entretanto, poucos estudos tratam do comportamento desse aço frente a utilização, direta ou indireta, de processos de soldagem. Desse modo, esse trabalho analisou a influência na estrutura e, nas propriedades mecânicas (dureza e taxa de desgaste) superficiais, do aço VP 100 quando submetido a um processo de tratamento térmico superficial. O processo de tratamento térmico superficial foi realizado através da execução de sucessivos cordões de solda, autógenos, na superfície do material, por meio de um sistema de laser de estado sólido Nd:YAG na condição pulsado. O aço VP 100 foi inicialmente investigado quanto a presença de isotropia em sua estrutura, visando excluir a direção adotada para tratamento térmico como fator influenciador nos resultados. Com uma estrutura visualmente semelhante em todas as direções e, com valores de dureza médios muito próximos entre direções, a direção adotada foi excluída como fator de influência no processo. Em seguida, realizou-se cordões de solda, autógenos, em seis condições distintas (SG, AR, N, N1, N2 e N3), analisados posteriormente através de ensaios de microdureza Vickers, para determinação da melhor condição para execução do tratamento térmico. As condições N1, N2 e N3 (todas com utilização de gás nitrogênio), apresentaram os melhores resultados de dureza (superficialmente e na faixa de profundidade de 0,30 mm), sendo escolhidas para a execução do tratamento térmico. Os corpos de prova tratados termicamente foram analisados através de difratogramas de raios-x e réplica por extração de carbono. Em nenhuma das duas análises houve a detecção da formação de nitretos no metal pós-tratamento. Ainda acerca dos difratogramas de raios-x, os dados obtidos mostraram a mudança da estrutura do material, de bainítica para martensítica, e a redução do tamanho dos cristalitos nas três condições. Os ensaios de taxa de desgaste mostraram melhores resultados para as condições de maior dureza, com melhores resultados na condição N3. Por fim, a condição N3 foi estipulada como a melhor condição, dentre as analisadas, para realização de tratamento térmico superficial no aço VP 100, apresentando além de uma elevação na dureza, uma baixa taxa de desgaste, fatores atribuídos à formação de uma estrutura martensítica, redução do tamanho dos cristalitos e intersticialização de nitrogênio no metal pós-tratamento térmico. / Among the steels currently available, is steel VP 100, a tool steel used in the mold and matrix manufacturing sector. There are many research on the machining process forward in this steel. However, few studies deal with work from this steel versus a direct or indirect use of welding processes. In this way, this work analyzed the influence on the structure and, under the mechanical conditions (hardness and wear rate), of the VP 100 steel when subjected to a superficial thermal treatment process. The surface heat treatment process was performed through the execution of successive weld beads, autogenous, on the surface of the material by means of a Nd: YAG solid state laser system in pulsed condition. The VP 100 steel was first investigated for the presence of isotropy in its structure, aiming the analysis if the direction took adopted for the heat treatment as an influencing factor in the results. With a visually similar structure in all directions and, with the average hardness values very close between the directions, the adopted direction was excluded as a factor of influence in the process. In the next step, weld beads, autogenous, were produced in six different condition (SG, AR, N1, N2 and N3), posterior analyzed by means of Vickers microhardness tests to determine the best condition for heat treatment. The N1, N2 and N3 conditions (all using nitrogen gas) presented the best hardness results (superficially and in the depth range of 0.30 mm), being chosen for the execution of the thermal treatment. The thermally treated specimens were analyzed by x-ray diffraction and replication by carbon extraction. In none of the two analyzes was the detection of nitride formation in the metal after treatment. Still about the x-ray diffractograms, the data obtained showed the change in the structure of the material, from bainitic to martensitic, and the reduction of the size of the crystallites in the three conditions. The wear rate tests showed better results for the best hardness conditions, with better results in the N3 condition. Finally, the condition N3 was stipulated as the best parameters, among the analyzed ones, for the accomplishment of superficial thermal treatment in the steel VP 100, presenting a rise in the hardness besides a low rate of wear, factors attributed to the formation of a martensitic structure, crystallite size reduction and nitrogen interstitialization in the post-heat treatment metal. / CAPES:DS 1517021

Nesta tese utilizamos o modelo do replicador aleatório, proposto por Diederich e Opper, para analisar as propriedades de equilíbrio de ecossistemas complexos (formados por um grande número de espécies) em três situações distintas. Na primeira parte desta tese, investigamos os efeitos de interações variáveis sobre a estrutura do ecossistema, utilizando o método de réplicas generalizado, introduzido por Penney et al. Este formalismo propõe uma nova interpretação para o índice de réplicas n, a saber, como sendo a razão entre duas temperaturas características: a temperatura relacionada aos acoplamento e a temperatura associada às variáveis de spin. Empregando t\\\'ecnicas de campo m\\\'edio de Mec\\^anica Estat\\\'stica e tamb\\\'em simula\\c\\~oes num\\\'ericas tratamos, em particular, do estado fundamental ($\\beta ightarrow + \\infty$). Encontramos dois regimes distintos, um onde prevalece a coopera\\c\\~ao entre as diferentes esp\\\'ecies ($\\beta^{\\prime} > 0$) e outro no qual a competi\\c\\~ao \\\'e predominante ($\\beta^ < 0$). No primeiro caso temos uma transi\\c\\~ao descont\\\'{\\i}nua para um regime de diversidade nula e no outro temos uma m\\\'axima diversidade das esp\\\'ecies. Na segunda parte desta tese \\cite, estudamos as implica\\c\\~oes de uma temperatura finita sobre a estrutura do ecossistema. Utilizamos a regra de Hebb para descrever as intera\\c\\~oes entre as diferentes esp\\\'ecies. A temperatura surge, no modelo, atrav\\\'es de um ru\\\'do gaussiano introduzido na equa\\c\\~ao estoc\\\'astica que rege a din\\^amica do processo. Tratamos analiticamente o caso recozido ({\\em annealed}), no qual as caracter\\\'sticas das esp\\\'ecies evoluem t\\~ao rapidamente quanto suas concentra\\c\\~oes, e o caso temperado ({\\em quenched}), onde tais caracter\\\'sticas est\\~ao fixas. Conclu\\\'{\\i}mos que h\\\'a uma transi\\c\\~ao de fase descont\\\'{\\i}nua entre um estado onde a competi\\c\\~ao prevalece, determinando baixa diversidade, para outro estado onde predomina a coopera\\c\\~ao. Por fim \\cite, analisamos as poss\\\'veis consequ\\^encias de uma interven\\c\\~ao humana sobre as propriedades de equil\\\'{\\i}brio do ecossistema. Admitimos o princ\\\'pio da exclus\\~ao competitiva para modelar os acoplamentos entre as diferentes esp\\\'ecies, a regra de Hebb. Interferimos na comunidade impondo que um conjunto de caracteres, selecionados previamente, esteja presente em uma fra\\c\\~ao bem definida dos seus membros. O principal resultado deste estudo revela, desde que o par\\^ametro de competi\\c\\~ao entre indiv\\\'duos semelhantes n\\~ao seja muito pequeno, que o efeito de uma tal manipula\\c\\~ao conduz a perda da diversidade e, portanto, ao empobrecimento do ecossistema. / In this thesis we use the random replicator model, proposed by Diederich and Opper \\cite, to analyse the equilibrium properties of complex ecosystems (formed by a large number of species) in three distinct situations. In the first part of this thesis \\cite, we investigate the effects of variable interactions upon ecosystem structure, using the generalized replica method, introduced by Penney et al \\cite. In this formalism we find a new interpretation for the replica number $n$ as the ratio between two characteristic temperatures: the temperature related to the couplings ($\\beta^$) and the temperature associated to the spin variables ($\\beta$). We approach the problem using mean field methods of statistical mechanics and intensive numerical simulations; in particular we are concerned with the ground state ($\\beta ightarrow + \\infty$). We find two distinct regimes, one where cooperation between different species prevails ($\\beta^ > 0$) and the other in which competition is predominant ($\\beta^ < 0$). In the first case we have a discontinuous transition to the zero diversity regime and in the other we have the maximum species diversity. In the second part of this thesis \\cite, we examine the finite temperature implications upon ecosystem structure. Through the Hebb rule we can describe the interactions between different species. With the aid of a Gaussian noise in the stochastic equation, that governs the temporal evolution, we have a way to introduce the finite temperature in the model. We treat analytically the annealed case, in which the species characteristics evolve so fast as its concentrations, as well as the quenched case, in which such characteristics are fixed. We conclude that there is a discontinuous phase transition between a state where competition prevails, implying low diversity, to another state in which cooperation is stronger. At last \\cite, we analyse the possible consequences of human intervention upon the equilibrium properties of the ecosystem. We assume the competitive exclusion principle to model the couplings between different species, the Hebb rule. We interfere in the community by imposing that a set of characters, previously selected, be present in a well defined fraction of its members. The main result of this study reveals, provided that the intraspecies competition parameter is not too weak, that the effect of such a manipulation leads to the impoverishment of the ecosystem.

REPLICA is a PRAM-NUMA hybrid architecture, with support for instructionlevel parallelism as a VLIW architecture. REPLICA can also chain instructionsso that the output from an earlier instruction can be used as input to a laterinstruction in the same execution step. There are plans in the REPLICA project to develop a new C-based program-ming language, compilers and libraries to speed up development of parallel pro-grams. We have developed a LLVM back-end as a part of the REPLICA projectthat can be used to generate code for the REPLICA architecture. We have alsocreated a simple optimization algorithm to make better use of REPLICAs supportfor instruction level parallelism. Some changes to Clang, LLVMs front-end forC/C++/Objective-C, was also necessary so that we could use assembler in-liningin our REPLICA programs. Using Clang to compile C-code to LLVMs internal representation and LLVMwith our REPLICA back-end to transform LLVMs internal representation intoMBTAC1 assembler. / REPLICA är en VLIW liknande PRAM-NUMA arkitektur, med möjlighet för attkedja ihop instruktioner så att resultat från tidigare instruktioner kan användassom indata till nästa instruktion i samma exekveringssteg. Inom REPLICA projetet finns planer på att utecklar ett nytt C-baserat pro-grammeringsspråk, kompilatorer och bibliotek för att snabbba upp utvecklingen avparallella program. Som en del av REPLICA projektet har vi utvecklat ett kompi-lator back-end för LLVM som kan användas för att generera kod till REPLICA. Vihar även utvecklat en enklare optimerings algoritm för att bättre utnyttja REPLI-CAs förmåga för instruktions parallelisering. Vi har även gjort ändringar i Clang,LLVMs front-end för C/C++/Objective-C, så att vi kan använda inline assembleri REPLICA program. Med Clang kan man kompilera C-kod till LLVMs interna representation somi sin tur genom LLVM och REPLICA back-end kan omvandlas till MBTAC3 as-sembler.

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The efficiency of parallel tempering Monte Carlo is studied for a two-dimensional Ising system of length L with N=L^2 spins. An external field is used to introduce a difference in free energy between the two low temperature states. It is found that the number of replicas R_opt that optimizes the parallel tempering algorithm scales as the square root of the system size N. For two symmetric low temperature states, the time needed for equilibration is observed to grow as L^2.18. If a significant difference in free energy is present between the two states, this changes to L^1.02. It is therefore established that parallel tempering is sped up by a factor of roughly L if an asymmetry is introduced between the low temperature states. This confirms previously made predictions for the efficiency of parallel tempering. These findings should be especially relevant when using parallel tempering for systems like spin glasses, where no information about the degeneracy of low temperature states is available prior to the simulation.

<p> In the past, analog circuits, discrete digital logic circuits or minicomputers have been used to implement the signal processing section of a sonar systems. More recently, microprocessor based logic circuit designs have produced a new breed of system design approach which gives designers the flexibility that has never been available through the use of analog or discrete logic circuits; however, due to the inherent slow speed of the metal-oxide semiconductor (MOS) logic circuits, incorporating microprocessors in the implementation of a sonar signal processor is not feasible. With the advent of bipolar Schottky large scale integrated circuit technology, the speed performance of the microprocessors have been improved considerably, and signal processor designs employing microprocessors are now feasible. </p> <p> The main objective of this work is to design, implement, and test a real-time digital sonar signal processor for processing pulsed CW signals. With design based on the use of the bit slice microprocessor, a signal processor has been constructed that has an 8 bit input, a 16 bit output. The processor is capable of detecting 16 different Doppler shifts. Laboratory generated signals are used in the testing and the experimental results show good agreement with the theory. A possible means of expanding the existing single channel signal processor into a multichannel processor has also been outlined. </p> / Thesis / Master of Engineering (MEngr)

This project tries to understand how we alter existing architecture. The research leads to a proposal that attempts to answer the question: Should a death of a building be a part of its envisaged timeline? It is difficult to preempt a building being dead, but it might be possible to preempt a building being refurbished, renovated and especially replicated. I will try to incorporate the dimension of time in the new buildings and embrace the inevitable change, as well as explore the friction between originality and copying that the process of alteration generates. The site chosen for this architectural experiment is a ski jump erected at Norra Djurgården, and the proposal is its morphed copy hosting a visitors centre and an urban sports centre. The ambition is to establish guidelines or principles of mimicking and copying the elements of an existing edifice in the new one.

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