Otimização dos parâmetros de fresamento frontal em aço HARDOX®450 baseada na rugosidade e na força resultante

O Hardox450 é um aço estrutural laminado e temperado, com alto teor de manganês (o que induz ao encruamento), com alta dureza (450 HB), alta resistência mecânica (1200 MPa), projetado para resistir ao desgaste por abrasão, trincas e quebras. Devido a suas excelentes propriedades mecânicas, tem-se uma maior vida útil de equipamentos como britadores, caçambas e engrenagens. Porém, tais propriedades resultam em baixa usinabilidade. Assim, objetiva-se encontrar os parâmetros ideais de fresamento frontal em aço Hardox450 visando menores valores de rugosidade média (Ra) e força resultante (FR). Com a utilização do projeto de experimentos Box-Behnken, os parâmetros de entrada (velocidade de corte vc, avanço por dente fz e profundidade axial de corte ap) foram combinados em três níveis cada. A partir da análise de variância, observou-se que ap foi o parâmetro mais significativo. Na otimização dos parâmetros, a otimização multivariada sugere a combinação vc = 88 m/min, fz = 0,10 mm/dente e ap = 0,20 mm para obtenção de um processo com menores valores de FR (111 N) e Ra (0,135 μm) simultaneamente. Além disso, a presença do desgaste precoce da ferramenta sugere um estudo mais aprofundado sobre o fenômeno.Hardox450 is a rolled, hardened structural steel that has high manganese content (which induces work hardening), high hardness (450 HB), and high mechanical strength (1200 MPa), which is designed to resist by abrasion wear, cracks, and breakages. This material allows a longer service life of equipment such as crushers, buckets, and gears due to their excellent mechanical properties. However, these properties result in low machinability. Therefore, the objective is to find the best Hardox450 steel end milling parameters aiming at lower values of average roughness (Ra) and machining force (FR). The input parameters (cutting speed vc, feed per tooth fz, and axial depth of cut ap) were combined on every three levels using the Box-Behnken design of experiments. The analysis of variance showed that ap was the most significant parameter. Improving the combination of input parameters, the multivariate optimization suggests vc = 88 m/min, fz = 0.10 mm/tooth and ap = 0.20 mm to obtain a process with lower FR (111 N) and Ra (0.135 μm) values simultaneously. Besides, the occurrence of early tool wear suggests a more detailed study of this phenomenon

Essays in international finance

The present thesis comprises three essays in international finance, with a focus on the foreign exchange market. The first chapter assesses the predictive ability of a comprehensive set of empirical models of exchange rates, in addition to a standard technical trading strategy, on monthly exchange-rate returns for four developed and four emerging countries across different horizons. I implement a rolling window approach to the estimation and forecasting of the models, and construct an encompassing forecast. I also assess the economic value of the out-of-sample forecasting power of the empirical models using a simple dynamic allocation strategy, and find three key results: (1) the Taylor rule model consistently outperforms, economically and statistically, all the other models at the 1-month horizon. (2) The technical rule has superior predictive power over the random walk benchmark, across horizons, particularly for developed markets. (3) There are statistical gains from an unrestricted combined forecasting model at the 1-month horizon. The second chapter constitutes a survey that focuses on internationally tradable goods and services. Our motivation is that while excellent surveys exist in the literature on this topic, they focus largely on broad baskets of prices and, most commonly, on the consumer price index. We instead focus on the specific subset of the relevant literature that analyses deviations from the LOP applied to individual goods and services and specific sectors. The emphasis is hence on tradable items rather than broad baskets that also include a substantial nontradable component. Specifically, the objective is to distil the literature on the properties of deviations from the LOP applied to internationally tradable goods or sectors. We conclude that a careful reading of the literature suggests that this notion of PPP holds in the long run for a broad range of tradable goods and services and for a broad set of currencies. In the third chapter, I build a "commodity currency strategy" for exchange rate forecasting that conditions on changes in the global prices of commodity indices. The risk-return profile of this strategy reveals that the predictive ability of commodity prices for the exchange rate appears to be significant, and the returns appear to be uncorrelated to popular exchange rate strategies such as the carry trade and currency momentum. The market factor captures more than 70% of the cross-sectional returns of the proposed strategy and suggests a negative relation between equity returns and currency returns that are driven by commodity price changes. The commodity currency strategy is prone to high transaction costs which can only be circumvented by investing in developed markets with low costs and high liquidity

EFEITO DA FONTE DE LIPASE NA PRODUÇÃO DE UM ÉSTER DE ÁCIDO GÁLICO POR ESTERIFICAÇÃO EM MEIO DE SOLVENTE

O presente trabalho teve como objetivo a produção enzimática de um éster com atividade antioxidante (galato de isoamila) por esterificação de ácido gálico e álcool isoamílico em meio de solvente (terc-butanol). Oito lipases comerciais de diferentes fontes (microbianas e animal) foram empregadas na forma livre (extratos brutos) como biocatalisadores. As reações foram conduzidas empregando 0,25 mol L-1 de cada reagente (ácido gálico e álcool isoamílico), agitação mecânica de 240 rpm, 40°C, 4 h de reação e 1000 unidades de atividade enzimática baseada na hidrólise da emulsão de azeite de oliva. Os máximos valores de porcentagem de conversão foram obtidos para as preparações de lipase de Pseudomonas fluorescens – LPF (41,5 ± 5,1%) e de pâncreas suíno – LPP (38,4 ± 2,3%), a preparação de lipase testada com menor custo. A produtividade para estes sistemas de reação foi da ordem de 25 µmoles de ácido gálico consumido h-1 U-1. Estes revelam que a aplicação de uma lipase de baixo custo (LPP) pode ser promissora na produção de ésteres com propriedades antioxidantes, uma importante classe de compostos empregados na área de alimentos e cosméticos

Investigação do fresamento frontal do aço Hardox® 450 sob diferentes condições lubrirrefrigerantes

O Hardox® é um aço martensítico, caracterizado por elevada dureza e resistência ao desgaste abrasivo, cada vez mais empregado nas indústrias agrícola, mineradora e de transporte. Em determinados contextos, sua aplicação exige a fabricação de componentes através de usinagem, onde comumente se necessita atingir elevada produtividade e baixa rugosidade na superfície usinada. Neste cenário, a otimização de parâmetros de corte e a correta aplicação dos meios lubrirrefrigerantes possuem um papel fundamental para atingir tais objetivos. Desta forma, este trabalho visa investigar os efeitos e otimizar os parâmetros de corte, além de avaliar diferentes condições lubrirrefrigerantes no fresamento frontal do Hardox® 450 considerando a força de usinagem e a rugosidade da superfície usinada. O estudo avaliou as parcelas estática e dinâmica da força de usinagem, suas componentes ativa e passiva, e as rugosidades média, média parcial e total. Foram utilizados insertos de metal duro com revestimento PVD. As condições lubrirrefrigerantes avaliadas foram: fluido de corte em abundância, usinagem a seco, e nanofluido (NF) à base de flocos de grafeno multicamadas (MLG) aplicado em quantidade reduzida (RQL). Para planejar e processar os dados estatísticos coletados, utilizou-se o projeto de experimentos de Box-Behnken. Os resultados obtidos mostram-se favoráveis à utilização do NF-RQL pois gerou os menores valores de rugosidade e valores de força similares aos demais métodos para as condições de corte abordadas, além de configurar uma alternativa de menor impacto ambiental frente à lubrificação abundante.Hardox® is martensitic steel characterized by high hardness and resistance to abrasive wear, increasingly used in the agricultural, mining, and transport industries. In specific contexts, its application requires components manufactured through machining, where it is commonly necessary to achieve high productivity and low roughness on the machined surface. In this scenario, the cutting parameters’ optimization and the correct application of lubricating means play a fundamental role in achieving these goals. Thus, this work aims to investigate the effects and optimize the cutting parameters, even evaluate the different lubricooling conditions in end milling of Hardox® 450 considering the machining force and surface roughness. The study evaluated the static and dynamic portions of the machining force, its active and passive components, and the average, partial mean, and total roughness. PVD-coated carbide inserts were used. Cutting fluid in abundance, dry machining, and multilayer graphene-based nanofluid (NF-MLG) applied in reduced quantity lubrication (RQL) were the lubricooling conditions evaluated. The Box-Behnken design of experiments was used to plan and process the collected statistical data. The results obtained are favorable to use NF-MLG because it generated the lowest roughness values and force values similar to the other methods for the cutting conditions addressed, besides configuring an alternative with less environmental impact against abundant lubrication

Multi-objective optimization of cutting parameters for finishing end milling Hardox® 450

Hardox®450 is pre-hardened structural steel with high hardness and mechanical strength, designed to resist under abrasion wear, cracks, and breakages. This material provides a longer service life for crushers, buckets, and gears due to its excellent mechanical properties, which result in low machinability. Moreover, the knowledge about machining this material is limited, justifying further investigation. Thus, this study aims to evaluate the influence of cutting speed (vc), axial depth of cut (ap), and feed per tooth (fz) on the machining forces and surface finish during the finishing end milling of Hardox®450 with a CVD-coated carbide tool. The experiment was planned and analyzed through a 3-factor, 3-level Box-Behnken Design. The analysis of variance showed that apwas the most significant parameter for all response variables considered in this study. A multiobjectiveoptimization was carried out to determine the ideal levels of cutting parameters, considering the lowest values of static and dynamic machining forces and average and total surface roughnesses. The model suggests that the best results are achieved with vc=89m/min, fz=0.1mm/tooth, and ap=0.212 mm.Even with efficient results, the predicted and measured response variables differed slightly (mainly due to tool wear)

Farm advisory services and knowledge growth in Italy: comparison among three regional intervention models

The profound changes in European policy for farms advisory services (FAS) require a period of experimentation and results observation before the new CAP 2021-2027. This paper focuses on Measure 2 of Rural Development Programme (RDP) 2014-2020. The paper is focused on the description of case studies in three Italian regions: Campania, Emilia-Romagna and Veneto. Different Measure 2 – sub-measure 2.1 models are analyzed through a qualitative approach, using a conceptual framework adapted by Birner et al. (2009). The paper contributes to the ongoing debate in the scientific literature on the strengths and weakness of policy intervention focused on tailored advisory services to force a broader Agricultural Innovation System

The European trust crisis and the rise of populism

We study the implications of the Great Recession for voting for antiestablishment parties, as well as for general trust and political attitudes, using regional data across Europe. We find a strong relationship between increases in unemployment and voting for nonmainstream parties, especially populist ones. Moreover, unemployment increases in tandem with declining trust toward national and European political institutions, though we find only weak or no effects of unemployment on interpersonal trust. The correlation between unemployment and attitudes toward immigrants is muted, especially for their cultural impact. To explore causality, we extract the component of increases in unemployment explained by the precrisis structure of the economy, in particular the share of construction in regional value added, which is strongly related both to the buildup preceding and the bursting of the crisis. Our results imply that crisis- driven economic insecurity is a substantial determinant of populism and political distrust

Using neural networks for sales forecast in retail industry

Neste trabalho, explora-se o uso de redes neurais na previsão de vendas no varejo. Com essa técnica foram elaboradas previsões a partir de dados históricos de vendas de produtos de uma empresa do varejo. Foram gerados modelos com o uso de dados de venda de cada um dos produtos da base de dados, semana a semana. Os resultados sugerem que a modelagem por meio de redes neurais artificiais pode ser considerada adequada para a previsão de demanda de produtos no nível individual (produto a produto). Os modelos obtidos com o uso da metodologia proposta podem prever as vendas de produtos no curto prazo com maior precisão do que as técnicas naïve não-ajustada e de regressão linear, mais freqüentemente utilizadas.En este trabajo, se investiga el uso de redes neurales en la previsión de ventas al por menor. Con esa técnica se elaboraron previsiones a partir de datos históricos de ventas de productos de una empresa minorista. Se generaron modelos con el uso de datos de venta de cada uno de los productos de la base de datos, semana a semana. Los resultados sugieren que el modelado por medio de redes neurales artificiales puede ser considerado adecuado para la previsión de demanda de productos considerados individualmente (producto por producto). Los modelos obtenidos con el uso de la metodología propuesta pueden prever las ventas de productos a corto plazo con mayor precisión que las técnicas naïve no ajustada y de regresión lineal, más frecuentemente utilizadas.This paper explores the use of artificial neural networks in sales forecasts in retailing industry. Historical data is used to make forecasts of product sales in the retailing industry. Weekly sales data from individual products were used to generate models. Results sugest that models based upon neural networks can be adequate to individual product sales forecast. Models obtained with the proposed methodology are able to predict product sales in the short term more accurately then non adjusted naïve techniques and linear regression, more frequently used

Inhibition of Class I Histone Deacetylase Activity Blocks the Induction of TNFAIP3 Both Directly and Indirectly via the Suppression of Endogenous TNF-α

Histone deacetylase inhibitors (HDIs) are promising drugs for the treatment of inflammatory diseases. However, their therapeutical exploitation is slowed down by severe adverse manifestations that can hardly be foreseen, mainly due to incomplete knowledge of how HDIs impact the delicate balance of inflammatory mediators. In this work, we characterized the effects of the HDI trichostatin A (TSA) on the expression of TNFAIP3, which is a crucial inhibitor of the classical NF-kB pathway and an LPS-induced negative feedback regulator. The accumulation of TNFAIP3 mRNA after LPS stimulation showed biphasic behavior, with one wave within the first hour of stimulation and a second wave several hours later, which were both reduced by TSA. By using inhibition and knockdown approaches, we identified two temporally and mechanistically distinct modes of action. The first wave of TNAIP3 accumulation was directly blunted by the histone deacetylase (HDAC) blockade. By contrast, the second wave was decreased mainly because of the lack of endogenous TNF-α induction, which, in turn, depended on the intact HDAC activity. In both cases, class I HDACs appeared to play a nonredundant role, with HDAC3 required, but not sufficient, for TNF-α and TNFAIP3 induction. In addition to TNFAIP3, TNF-α is known to induce many response genes that orchestrate the inflammatory cascade. Thus, suppression of TNF-α may represent a general mechanism through which HDIs regulate a selected set of target genes