Abstract Grain boundaries are fundamental in the mechanical behavior of ultrafine grain materials, especially coincidence site lattice grain boundaries (CSL-GB). This research aims to identify the influence of CSL-GB on the hardness and electrical conductivity of a CuCrZr alloy subjected to rotary swaging after having undergone severe plastic deformation via equal channel angular pressing and aging. Vickers hardness was evaluated, and electrical conductivity was measured using the 4-point technique. The average grain size and CSL-GB distribution were identified using backscattered electron diffraction. Dislocation density was measured via X-ray diffraction. At the end of the swaging processing of CuCrZr alloy with preexistent ultrafine grains, the dislocation density ceases to be the significant influencer parameter on the modification of properties, and the grain boundaries pass to be more impacting. The reduction of CSL-GB and the concomitant increase in high-angle grain boundaries can decrease hardness and electrical conductivity. materials CSLGB. CSLGB CSL GB . (CSL-GB) aging evaluated 4point point 4 technique diffraction Xray X ray grains properties impacting highangle high angle (CSL-GB

ABSTRACT This article proposes an investment model for a renewable energy generator that allows it to earn the right to issue Renewable Energy Certificates (RECs) and sell them through quarterly sales auctions promoted by the blockchain. Blockchain technology can further promote the RECs market, as it enables tokenization and distribution of certificates. We did not find articles in the literature that analyze the decision to invest in decentralized autonomous organizations (DAOs) that have rules for issuing and trading RECs specified in smart contracts, which are executed and validated by the blockchain. This article contributes to the literature on blockchain technology applications in the renewable energy market by proposing issuing and selling RECs tokens through a DAO. The relevance of this research is that it shows that simple real option pricing methods can help decision-makers evaluate investment opportunities under uncertainty and flexibility. The tokenization and distribution of RECs via blockchain can promote transaction agility, reduce or eliminate bureaucracy in the means of payment, and increase the security and transparency of transactions. We propose a model for issuing and selling RECs in smart contracts. We assume that the generator has the flexibility to invest now or in one year to enter the platform, considering the energy generated in one year by a single typical 4MW wind turbine. Our model assumes that the price of the REC token follows an inverse demand function subject to stochastic shocks. The results contribute to the understanding of the performance dynamics of digital products under uncertainty and flexibility and show that distributed ledger technology (DLT) may be a viable alternative for renewable energy incentives. (RECs certificates DAOs (DAOs contracts DAO decisionmakers makers agility payment transactions platform MW turbine shocks DLT (DLT incentives

RESUMO Este artigo propõe um modelo de investimento para uma geradora de energia renovável que lhe permite ganhar o direito de emitir Certificados de Energia Renovável (CERs) e vendê-los por meio de leilões de vendas trimestrais promovidos por blockchain. A tecnologia blockchain pode promover ainda mais o mercado de CERs, pois permite a tokenização e distribuição de certificados. Não identificamos artigos na literatura que analisem a decisão de investir em organizações autônomas descentralizadas (OADs) que possuem regras para emissão e negociação de CERs especificadas em contratos inteligentes, que são executados e validados por blockchain. Este artigo contribui com a literatura sobre aplicações da tecnologia blockchain no mercado de energia renovável ao propor a emissão e venda de CERs do tipo token por meio de uma OAD. A relevância desta pesquisa recai sobre o fato de que ela mostra que métodos simples de precificação de opções reais podem ajudar os tomadores de decisão a avaliar oportunidades de investimento com incerteza e flexibilidade. A tokenização e distribuição de CERs via blockchain podem conferir agilidade às transações, reduzir ou eliminar a burocracia nos meios de pagamento e aumentar a segurança e transparência das transações. Propomos um modelo para emissão e venda de CERs em contratos inteligentes. Pressupomos que a geradora tem flexibilidade para investir agora ou dentro de um ano para adentrar a plataforma, considerando a energia gerada em um ano por uma única turbina eólica típica de 4 MW. Nosso modelo pressupõe que o preço do CER do tipo token adota uma função de demanda inversa sujeita a choques estocásticos. Os resultados contribuem para a compreensão da dinâmica de desempenho de produtos digitais com incerteza e flexibilidade e mostram que a tecnologia de ledger distribuído (TLD) pode ser uma alternativa viável para incentivos de energia renovável. (CERs vendêlos vendê los certificados OADs (OADs inteligentes OAD transações plataforma MW estocásticos TLD (TLD

ABSTRACT During production and heat treatments of aluminum alloys, numerous second phase particles form, which maximizes their mechanical properties. This work aimed to perform a correlation between Vickers hardness and X-ray diffraction results, when 7475-T7351 aluminum alloy processed by the cross rolling is subjected to annealing heat treatments (AHT) at 500 °C for different soaking times (15, 30 and 60 minutes) and for a soaking time of 15 minutes at different temperatures (200, 300 and 400 °C). The influence of the AHT (500 °C / 15 minutes) on the microstructure, via scanning and transmission electron microscopy, and tensile tests properties was also investigated. The results show evidence that the Vickers hardness decreased for AHT performed at 200 and 300 °C / 15 minutes and increase for greater temperatures and times. This behavior is probably due to modifications in the constituent/dispersoid particles and aluminum matrix observed from the X-ray analysis. Partial recrystallization and a coarsening of the precipitates was observed after the AHT at 500 °C / 60 minutes, whose brought harmful effects on the tensile mechanical properties.

RESUMO Contexto: diversos métodos para avaliação de opções reais foram extensivamente estudados e publicados. Mas as árvores binomiais recombinantes, conhecidas como treliças, talvez sejam uma das abordagens mais práticas e intuitivas para modelar incertezas e precificar flexibilidades gerenciais de projetos. Apesar de o modelo de árvore binomial de Cox, Ross e Rubinstein (1979) ser de simples implementação para opções financeiras, essa modelagem para opções reais requer uma abordagem diferente, como a proposta por Copeland e Antikarov (2001), que considera os fluxos de caixa do projeto como dividendos. Objetivo: neste tutorial, propomos um código em software aberto com diretrizes intuitivas para ajudar pesquisadores e profissionais a modelar malhas binomiais de opções reais a partir de fluxos de caixa de projetos. Método: nosso código considera a estimativa correta da volatilidade do projeto, a modelagem do rendimento de dividendos e a construção da treliça. Resultados: os resultados mostram como as opções reais podem afetar o valor de projetos. Conclusões: como contribuição, este tutorial fornece um mecanismo simples para analisar oportunidades de investimento em projetos que possuem incerteza e flexibilidade.

ABSTRACT Context: several methods for evaluating real options have been extensively studied and published. But recombining binomial trees, known as lattices, are perhaps one of the most practical and intuitive approaches to model uncertainty and price project managerial flexibilities for real options applications. Although the Cox, Ross, and Rubinstein (1979) lattice model is simple to implement for financial options, modeling real options lattices requires a different approach such as the one proposed by Copeland and Antikarov (2001), which considers project cash flows as dividends in the lattice model. Objective: in this tutorial, we propose a code in an open-source software with intuitive guidelines to help researchers and practitioners model real options lattices from project cash flows. Method: our code considers the correct project’s volatility estimation, dividend yield modeling, and lattice building. Results: the results show how real options can affect the value of projects. Conclusions: as a contribution, this tutorial provides a simple mechanism for analyzing investment opportunities in projects that have uncertainty and flexibility.

Resumo Objetivo: Determinar a estratégia ótima de investimento em equilíbrio de Nash para o mercado imobiliário residencial do Rio de Janeiro, considerando a incerteza na demanda por imóveis e o número de concorrentes ativos no mercado. Metodologia: Foi desenvolvido um modelo de jogos de opções reais. Os parâmetros do modelo foram estimados com ferramentas econométricas a partir de dados reais do mercado imobiliário carioca. Resultados: Os resultados quantitativos obtidos são intuitivos no sentido de que, quanto maior a quantidade de concorrentes, menor o nível de demanda exigido para o investimento em novas unidades, e quanto maior a volatilidade da demanda, maior o nível de demanda para ser ótimo o investimento. Contribuições: Este trabalho modificou a metodologia de Grenadier (2002), fornecendo uma especificação mais adequada e robusta da incerteza para a função de demanda, permitindo interpretações econômicas mais intuitivas.

Abstract Purpose: To determine the optimal investment strategy in Nash equilibrium for the residential real estate market of Rio de Janeiro, considering the uncertainty in the demand for real estate and the number of active competitors in the market. Design/methodology/approach: A Real Options Game model was developed. The parameters of the model were estimated with econometric tools using data from the Rio de Janeiro real estate market. Findings: The quantitative results obtained are intuitive in the sense that the larger the number of competitors, the lower the level of demand required for investment in new units, whereas the greater the volatility of demand, the greater the demand threshold for the investment to be optimal. Originality/value: This study modified the methodology of Grenadier (2002), providing a more adequate and robust specification of the uncertainty for the demand function, thus allowing more intuitive economic interpretations.

ABSTRACT Samples of the Al 7075 naturally and artificially aged were processed by conventional and asymmetrical rolling with 5% of thickness reduction. The rolling processes were evaluated under room temperature and under warm condition (130°C). Mechanical properties were evaluated by uniaxial tensile and Vickers microhardness tests. Microstructure evolutions were followed by optical microscopy analysis. Naturally aged samples showed better yield strengthening under warm processing. Greater ultimate stress and ductility under room temperature processing was also noticed in naturally aged specimens. Artificially aged samples showed better mechanical properties under room temperature, softening under warm processing due to grain recovery process. Microhardness tests showed expected results for both rolling types, especially on asymmetrical rolling with the higher predictions were observed. Micrographs have shown no expressive grain changes or refinement although its flattening was observed. Precipitates were analyzed by EDS/SEM revealing the presence of MgZn2 and CuMgAl along the matrix that provides plastic strengthening.

ABSTRACT The pure copper wires were wiredrawn at cryogenic and room temperatures. After deformation they presented important and significant differences in their crystallographic textures and microstructures. Therefore, this study aimed to investigate the evolution of crystallographic texture of pure copper drawn at temperatures of 295 K and 77 K and correlated them to the deformation micromechanisms. For this, the X ray diffraction (XRD) and electron backscattered diffraction (EBSD) techniques were used. The results showed that, after the deformation, the samples drawn at both temperatures showed Copper {112}<111>, X {110}<111> and Brass {110}<112> components as the most intense. In samples drawn at cryogenic temperature there was also observed the appearance of a R{124}<211> component, typical of recrystallization and the presence of the γ fiber {111}<uvw>, typical of deformation twin.

The 304L austenitic stainless steel is susceptible to mechanically induced martensitic transformation from slightly above room temperature down to cryogenic temperatures. In this work, austenitic 304L steel produced by two different thermomechanical processes, hot rolling (HR) and cold rolling and annealing (CR/A), were subjected to martensitic transformation by rolling and by tensile tests at 298 K and 155 K and the volume fraction of martensite was determined by X-ray diffraction and ferritescope measurements. The results showed that the martensitic transformation was complete for CR/A samples rolled at 155 K and that the volume fraction of martensite was larger in CR/A samples than in HR samples in all cases.

Analysis of dislocation density in metallic materials has been pursued with great interest for many years because dislocations are closely associated with plastic deformation and thus exert a deep effect on the mechanical properties of any material. Crystallographic texture has also a decisive influence in some properties. In this work, the dislocation density was estimated from the line broadening of X-ray diffractograms using the Convolutional Multiple Whole Profile Program (CMWP) and crystallographic texture analyses were performed using inverse pole figures (IPF). The material used in this research was pure copper deformed by cold rolling and Equal Channel Angular Pressing (ECAP). The dislocation density values obtained by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) were compared and discussed. While, in the case of cold rolling, the crystallographic texture of the material was enhanced with increasing deformation, it was reduced with increasing deformation in the case of ECAP processing.

ABSTRACT Nutcracker syndrome refers to the complex of clinical symptoms caused by the compression of the left renal vein (LRV) between the abdominal aorta and the superior mesenteric artery, leading to stenosis of the aortomesenteric portion of the LRV and dilatation of the distal portion. Hematuria, proteinuria, flank pain, varicocele and pelvic congestion may occur, occurring more frequently in young adults. Conservative management, might be the option whenever it is possible. When surgical treatment is required, classically open surgery have been performed, with major surgeries as LRV transposition or bypass techniques. The main caveats regards the fact that these are large and risky surgeries. Endovascular surgery with venous stent placement has gained some space as it is minimally invasive alternative. However, venous stents are associated with a high number of trombotic complications and in many cases requirement of life-long anticoagulants. External stenting of the LRV with this “shield technique” is a minimally invasive alternative, with good medium term results. We herein demonstrate our second experience with the technique of this surgery in a patient with 12 months of follow up and excellent results.

Stainless steels are well known by their corrosion resistance. The austenitic types, in particular, are also applied as structural components in engineering systems operating at high temperatures such as nuclear reactors, petrochemical furnaces and turbines. For these applications operational temperatures may go up to 800ºC. Under constant load applications the main mechanism of failure, which would limit the material's life, is creep. In the present work creep parameters were evaluated in the high temperature interval of 600 to 800ºC for an AISI 316 austenitic stainless steel. Dislocation substructures were observed by transmission electron microscopy in creep ruptured specimens. Two distinct mechanisms of dynamic strain aging and dynamic recovery associated with different values for the power law exponent n and the Arrhenius activation energy Q for creep were verified below and above 700ºC, respectively.

Two distinct AISI type 316 stainless steels, of Brazilian and Swedish origins, were compared regarding their creep fracture mechanisms at 600, 700 and 800°C. The possible mechanisms associated with the creep fracture strength were identified by means of fracture maps proposed either by Ashby and collaborators or by Miller and Langdon. Experimental creep results were consistent with the general Ashby and collaborators map for face centered cubic alloys. By contrast, the two different 316 steel displayed significant differences in the model-based map of Miller and Langdon. In the present work, changes in the maps frontier are proposed as well as the introduction of a new field in the map related to grain boundary precipitation. These propositions allowed the Miller and Langdon map to be coherent with the experimental creep fracture results of both 316 stainless steels.

RESUMO Neste trabalho foram preparadas dispersões aquosas de óxido de grafeno (GO) e óxido de grafeno reduzido (rGO), em diferentes tempos de oxidação, com o objetivo de verificar a influência do tempo de oxidação em relação às características das folhas (flakes) finais. As dispersões de GO foram preparadas pelo método de Hummers modificado utilizando os seguintes tempos de oxidação: 4 h; 1 dia; 3 dias; 7 dias e 10 dias. Em seguida, as dispersões de GO foram submetidas ao tratamento de redução com ácido ascórbico, obtendo-se o rGO. As caracterizações das amostras foram realizadas por meio das análises de espectroscopia Raman, espectroscopia de fotoelétrons excitados por raios X (XPS), microscopia eletrônica de varredura (MEV) e difração de raios X (DRX). A espectroscopia Raman mostrou a variação da relação de intensidade entre as bandas D e G (ID/IG) à medida que o tempo de oxidação foi aumentado. A análise de XPS exibiu a alteração dos percentuais de carbono (C) e oxigênio (O). Através de análise no MEV foi correlacionada a morfologia dos flakes com o aumento do tempo de oxidação. E por fim, com o auxílio de DRX, foi verificada a variação da distância interplanar.

ABSTRACT In this work aqueous dispersions of graphene oxide (GO) and reduced graphene oxide (rGO) were prepared in different oxidation times in order to verify the influence of the oxidation time on the characteristics of the final flakes. GO dispersions were prepared by the modified Hummers method, using the following oxidation times: 4 h; 1 day; 3 days; 7 days and 10 days. Afterwards the dispersions of GO were subjected to the reduction treatment with ascorbic acid, obtaining the rGO. Samples were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Raman spectroscopy showed the variation of the intensity ratio between the D and G bands (ID / IG) as the oxidation time was increased. The XPS analysis indicated the alteration of the percentages of carbon (C) and oxygen (O). The SEM analysis correlated the morphology of the flakes with the increase of the oxidation time. Finally, with the aid of XRD, the variation of the interplanar distance was verified.

RESUMO A inovação é um elemento importante para alavancar a competitividade das empresas brasileiras. Por outro lado, projetos inovadores tendem a ser caracterizados por inúmeras incertezas técnicas e de mercado. Este artigo propõe a fusão de estratégias de marketing com técnicas de gerenciamento de risco de projetos de desenvolvimento de novos produtos e novas tecnologias, aqui denominado de os 4P’s da inovação. A fim de ilustrar esta proposta, este modelo é aplicado a um projeto de TI a fim de determinar o seu valor e risco. Os resultados indicam que o uso conjunto de ferramentas de marketing e de gerenciamento de risco proposto neste modelo agrega valor ao projeto e pode reduzir a probabilidade do gestor tomar decisões equivocadas.

ABSTRACT Innovation is an important factor in increasing competitiveness of Brazilian enterprises. On the other hand, innovative projects are characterized by many technical and market uncertainties. This article proposes incorporating marketing strategies into risk management methods for the development of new products and technology projects, which we call the 4P's of innovation. To illustrate this concept, we apply this model to an IT project in order to determine its value and risks. The results indicate that the joint use of marketing and risk management tools proposed add value to the project and reduce the probability of the manager making bad decisions.

Abstract Electro-intensive industries account for a significant proportion of the total industrial electricity consumption, and these industries usually possess co-generation assets, which can supply at least part of their energy needs. However, due to price uncertainty, it may be optimal for the firm to temporarily suspend production and sell the available energy. If this strategy creates value, governments can create incentives through price signals for these firms to take their plants offline and increase the supply of electricity during times of shortage. This study analyzes the case of an aluminum plant that has the choice of temporarily suspending operations and models its managerial flexibility as a bundle of European switch options. The suspension and modeling would occur under two simultaneous situations, uncertainty and asymmetric state switching costs under the real options approach, to determine whether the changes add value to the firm. The results indicate that this flexibility can add significant value to the firm.