Devido à demanda de aumento de produtividade na indústria, a utilização de materiais mais leves, busca por processos de reparos com melhor custo, em conjunto com o avanço das tecnologias, evolução dos processos de soldagem, e esses fatores aliados aos benefícios de uma maior taxa de fusão, melhor controle da penetração, faz com que o processo MIG/MAG com polaridade variável apresente consideráveis avanços tecnológicos nos dias de hoje. Porém, a seleção dos parâmetros da curva típica de corrente do processo (composta por corrente de pico, corrente de base positiva e corrente negativa), é ainda um desafio. Buscando um melhor entendimento da influência da polaridade negativa no processo de soldagem, em especial para aplicações de revestimento, este trabalho tem como objetivo analisar os parâmetros da polaridade negativa individualmente em relação a geometria do cordão de solda, utilizando aço ao carbono como metal base e aço inoxidável como metal de adição. O planejamento e execução do experimento foi realizado com base na metodologia de projeto de experimentos Box-Behnken, variando três fatores: tempo de corrente negativa, intensidade de corrente negativa e tempo de corrente de base positiva, em três níveis cada um. Primeiramente alcançou-se a minimização da diluição, onde o tempo de corrente negativa apresentou efeito significativo no resultado final, sendo seu nível máximo (15 ms) o responsável pelos menores valores de diluição, aproximadamente 12%, recomendado em soldagem para revestimento. Posteriormente, foi avaliado o efeito dos parâmetros em relação à penetração, altura e largura do cordão de solda, sendo o tempo de corrente negativa em 15 ms e corrente negativa em -150 A os níveis que apresentaram melhores resultados. Após, os parâmetros da polaridade negativa utilizados foram comparados com os termos proporcionais sugeridos pela literatura (%EN). E, por fim, avaliou-se uma forma de curva de corrente sem a corrente de base positiva, onde foi concluído que não há significância das diferentes formas de curva de corrente sobre os resultados na penetração do cordão de solda, assim como a necessidade da corrente de base na estabilidade do arco elétrico do processo. / Due to the demand to increase productivity in the industry, use lighter materials, search for repair processes with better cost, in combination with advancement of technologies, evolution of welding processes, connected with the benefits of a higher melting rate and better control of the process penetration, it was possible to verify advances in the MIG / MAG Variable Polarity welding technique. However, the selection of the parameters of the typical process current curve (composed by peak current, positive current and negative current), is still a challenge today. The aim of this work is to analyze the negative polarity parameters individually in relation to the weld bead geometry, using carbon steel as base metal and stainless steel as addition metal. The planning and execution of the experiment was performed based on the Box-Behnken design methodology, varying three factors: negative current time, negative current intensity and positive base current time, at three levels each one. Firstly, dilution minimization was achieved, which showed that the negative current time had a strong influence on the final result, and the maximum level (15 ms) was responsible for the lowest dilution values, nearby 12%, ideal for welding cladding. Then, the parameters were evaluated in relation to penetration, height and width of the weld bead, which for welding cladding, the negative current time 15 ms and negative current -150 A presented better results. Next, the negative polarity parameters were compared with the proportional terms suggested by the literature (%EN). Finally, a form of current curve without positive base current was evaluated, where it can be concluded that the current curve form does not have significance on the penetration results, as well as the necessity of the base current in the arc electric stability.

O presente trabalho objetiva estudar a eficiência térmica do arco elétrico e de fusão para o processo de soldagem MAG, do inglês Metal Active Gas, em diferentes geometrias de juntas soldadas. As soldas foram feitas inicialmente em um calorímetro de fluxo contínuo de água, seguidas de deposição de cordão sobre chapa e soldagem de juntas em ângulo “T”, sempre em aço carbono. A metodologia de projeto de experimentos Box-Behnken foi empregada para a avaliação da influência da variação dos parâmetros de soldagem (tensão, velocidade de alimentação do eletrodo e velocidade de soldagem) nas eficiências, dentro do modo de transferência metálica por curto circuito. Diferentes equações propostas na literatura para o cálculo da eficiência de fusão são comparadas. Para a adequada aquisição da eficiência térmica pelo calorímetro, preliminarmente é avaliada a influência da vazão de água e da geometria na entrada de um calorímetro de fluxo contínuo sobre a eficiência térmica do arco. O procedimento experimental consiste em testar diferentes vazões de água e três configurações geométricas na região de entrada de água no calorímetro: com rolha reta, com difusor cônico e com obstáculo. Os experimentos foram planejados e os resultados avaliados com base na análise de variância estatística de um único fator, no caso, a vazão de água na entrada do calorímetro. A maior eficiência térmica média de 80,5% foi obtida para a vazão de 4 l/min, com baixo erro estatístico, utilizando rolha de entrada com geometria de difusor cônico. O modelo em que o fluxo entra diretamente no tubo apresentou todos os valores de eficiência térmica do arco com pequeno decréscimo numérico se comparados com o difusor cônico, enquanto a rolha com obstáculo apresentou elevado erro estatístico. Com base nos resultados descritos, a eficiência térmica do arco elétrico foi avaliada com a vazão de 4 l/min para o projeto de experimentos Box-Behnken, os valores obtidos estão na faixa de 72 a 82% conforme a combinação dos parâmetros de soldagem. A velocidade de soldagem e a tensão do arco se mostraram como os parâmetros de maior influência na eficiência térmica do arco. Os resultados relativos à eficiência de fusão indicam maiores valores nas soldas realizadas no calorímetro e por simples deposição sobre chapa. A junta T apresentou os menores valores de eficiência de fusão e de diluição para todos os casos. O parâmetro de maior influência na eficiência de fusão foi a corrente de soldagem. / The main aim of the present work is to study arc thermal efficiency and fusion efficiency to Gas Metal Arc Welding – GMAW, using different joint geometries. At first, the welds were performed in a continuous water flow calorimeter, followed by bead on plate and T – joint deposits. The Box-Behken design of experiments methodology was used to analyze the effect of welding parameters (arc voltage, wire feed speed and welding speed) on the efficiencies, when using short circuit metal transfer. The results of the fusion efficiency calculation were compared using different equations found in the literature. To correctly evaluate the thermal efficiency, it was necessary to analyze the influence of water flow rate and calorimeter inlet geometry. The experimental procedure consists of varying water flow rate and testing three different calorimeter inlet seal geometries: straight seal, conical diffuser seal and seal with water flux obstacle. The experiments were designed and the results evaluated based in a one-factor statistical analysis of variance, in this case the inlet calorimeter water flow. The highest average thermal efficiency is 80.5% to water flow of 4 l/min, with a low statistical error, using the conical diffuser seal inlet geometry. The inlet with straight seal model shown all the arc thermal efficiency values with slightly lower numerical values compared with conical diffuser, while the seal with flux obstacle exhibited high statistical error. Based on these results, the arc thermal efficiency was evaluated using 4 l/min water flow to the Box-Behnken Design, resulting values in the 72 to 82% range, depending on the welding parameters. The welding speed and arc voltage were the parameters that significantly affect arc thermal efficiency. The fusion efficiency results of the welds performed on the calorimeter and bead on plate were. The welds performed in T joints exhibit lowest fusion efficiency and dilution to each welding parameters combination tested. The fusion efficiency is strongly affected by the welding current.

This thesis deals with the possibility of applying the method of Design of Experiments (DoE) on specific data. In the first chapter of theoretical part, this method is described in detail. The basic principles and guidelines for the design of the experiment are written there. In the next two chapters, factorial design of the experiment and response surface design are described. The latter one includes a central composite design and Box-Behnken design. The following chapter contains practical part, which focuses on modelling firing range of ball from a catapult using the above three types of experimental design. In this work, the models are analysed together with their different characteristics. Their comparison is made by using prediction and confidence intervals and by response optimizing. The last part of the thesis comprises overall evaluation.

Future 450mm semiconductor wafer foundries are expected to produce billions of low cost, leading-edge processors, memories, and wireless sensors for Internet of Everything applications in smart cities, smart grids, and smart infrastructures. The problem has been a lack of wise investment decision making using traditional semiconductor industry models. The purpose of this study was to design decision-making models to conserve financial resources from conception to commercialization using real options to optimize production capacity, to defer an investment, and to abandon the project. The study consisted of 4 research questions that compared net present value from real option closed-form equations and binomial lattice models using the Black-Scholes option pricing theory. Three had focused on sensitivity parameters. Moore's second law was applied to find the total foundry cost. Data were collected using snowball sampling and face-to-face surveys. Original survey data from 46 Americans in the U.S.A. were compared to 46 Europeans in Germany. Data were analyzed with a paired-difference test and the Box-Behnken design was employed to create prediction models to support each hypothesis. Data from the real option models and survey findings indicate American 450mm foundries will likely capture greater value and will choose the differentiation strategy to produce premium chips, whereas higher capacity, cost leadership European foundries will produce commodity chips. Positive social change and global quality of life improvements are expected to occur by 2020 when semiconductors will be needed for the $14 trillion Internet of Everything market to create safe self-driving vehicles, autonomous robots, smart homes, novel medical electronics, wearable computers with streaming augmented reality information, and digital wallets for cashless societies.

Kitchen waste, which is collected in large amounts from cafeterias, restaurants, dining halls, food processing plants, and household kitchens, have become a valuable material for bioprocess engineering. Due to the high carbohydrate fraction, kitchen waste has great potential to be used as a potential substrate for ethanol production. Utilization of it as a raw material in ethanol fermentation would also contribute to reduction of costs. In the first part of this study, the effect of pretreatment method and enzymatic hydrolysis on glucose production was evaluated. Dry baker&rsquo / s yeast, Saccharomyces cerevisiae, was used in fermentation experiments conducted with and without fermentation medium at pH 4.5 and 30oC for 48 hours. Close values of glucose concentration were obtained from no pretreated and hot water treated samples. The fermentation results indicated that ethanol can be produced at similar concentrations in bioreactors with and without fermentation medium addition (p &gt / 0.05). Thus, it is concluded that use of kitchen wastes as is disposed and without fermentation medium in ethanol fermentation could lower the cost to a large extent. In the second part of this study, the effects of solid load, which is proportional to the glucose concentration (10% to 20% (w/w)), inoculum level of Saccharomyces cerevisiae (5% to 15% (v/v)), and fermentation time (48 to 96 h) on production of bioethanol from kitchen waste were studied using Response Surface Methodology (RSM). A three-factor Box Behnken design was used. Ethanol concentration was used as a response in the resulting experimental design. High Pressure Liquid Chromatography (HPLC) method was used to determine ethanol and glucose concentrations. The statistical analysis of the constructed model developed by RSM suggested that linear effects of solid load, inoculum level, and fermentation time and quadratic effects of inoculum level and fermentation time were all significant (p &lt / 0.05) on bioethanol production. The model was verified by additional runs, which were not present in the design matrix. It was found that the constructed model could be used to determine successfully the bioethanol concentration with &gt / 90% precision. An optimum ethanol concentration of 32.16 g/L was suggested by the model with 20% (w/w) solid load, 8.85% (v/v) inoculum level and 58.8 hours of fermentation. Further study is needed to evaluate the optimal fermentation conditions in a large scale fermentation

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-26T17:52:57Z No. of bitstreams: 1 BrenoGustavoPorfirioBezerra_DISSERT.pdf: 1680172 bytes, checksum: 0f4f20935e8e24b12e505645455bea08 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-28T19:06:56Z (GMT) No. of bitstreams: 1 BrenoGustavoPorfirioBezerra_DISSERT.pdf: 1680172 bytes, checksum: 0f4f20935e8e24b12e505645455bea08 (MD5) / Made available in DSpace on 2016-01-28T19:06:56Z (GMT). No. of bitstreams: 1 BrenoGustavoPorfirioBezerra_DISSERT.pdf: 1680172 bytes, checksum: 0f4f20935e8e24b12e505645455bea08 (MD5) Previous issue date: 2014-11-03 / A ?gua produzida representa um grande problema associado com a atividade de extra??o de ?leo bruto. O monitoramento dos n?veis de metais nos res?duos ? constante e requer a utiliza??o de t?cnicas anal?ticas sens?veis. No entanto, a determina??o de elementos tra?o muitas vezes pode exigir uma etapa de pr?-concentra??o. O objetivo deste trabalho foi desenvolver um m?todo anal?tico simples e r?pido para a extra??o e pr?-concentra??o baseada no fen?meno de extra??o no ponto nuvem para a determina??o do Cd, Pb e Tl em ?gua produzida amostras por Espectrometria de Absor??o de alta resolu??o com fonte continua e atomiza??o em forno de grafite. Um planejamento Box Behnken foi usado para obter a condi??o ideal de extra??o dos analitos. Os fatores avaliados foram: concentra??o do agente complexante (o,odietilditilfosfato am?nio, DDTP), a concentra??o do ?cido clor?drico e concentra??o do surfactante (Triton X -114). A condi??o ideal de extra??o foi obtida com: 0,6% m v -1 DDTP, HCl 0,3 mol L-1 e 0,2% m v -1 de Triton X - 114 para o Pb; 0,7% m v -1 DDTP, HCl 0,8 mol L-1 e 0,2% m v -1 Triton X-114 para Cd. Para o Tl foi evidenciado que melhor condi??o de extra??o se d? com aus?ncia de DDTP, as condi??es de extra??o foram ent?o HCl 1,0 mol L-1 e 1,0% m v -1 de Triton X - 114. Os limites de detec??o para o m?todo proposto, foram 0,02 ?g L-1 , 0,004 ?g L-1 e 0,06 ?g L-1 para o Pb, Cd e Tl, respectivamente. Os fatores de enriquecimento foram superiores a 10 vezes. O m?todo foi aplicado para a ?gua produzida da bacia Potiguar, e testes de adi??o e recupera??o foram realizados, e valores ficaram entre 81% e 120%. A precis?o foi expressa com desvio padr?o relativo (RSD) foi inferior a 5% / Produced water is a major problem associated with the crude oil extraction activity. The monitoring of the levels of metals in the waste is constant and requires the use of sensitive analytical techniques. However, the determination of trace elements can often require a pre-concentration step. The objective of this study was to develop a simple and rapid analytical method for the extraction and pre-concentration based on extraction phenomenon cloud point for the determination of Cd, Pb and Tl in produced water samples by spectrometry of high resolution Absorption source continues and atomization graphite furnace. The Box Behnken design was used to obtain the optimal condition of extraction of analytes. The factors were evaluated: concentration of complexing agent (o,o-dietilditilfosfato ammonium, DDTP), the concentration of hydrochloric acid and concentration of surfactant (Triton X -114). The optimal condition obtained through extraction was: 0,6% m v-1 DDTP, HCl 0,3 mol L-1 and 0,2% m v-1 of Triton X - 114 for Pb; 0,7% m v-1 DDTP, HCl 0,8 mol L-1 and 0,2% m v-1 Triton X-114 for Cd. For Tl was evidenced that best extraction condition occurs with no DDTP, the extraction conditions were HCl 1,0 mol L-1 e 1,0% m v-1 de Triton X - 114. The limits of detection for the proposed method were 0,005 ?g L-1 , 0,03 ?g L-1 and 0,09 ?g L-1 to Cd, Pb and Tl, Respectively. Enrichment factors Were greater than 10 times. The method was applied to the water produced in the Potiguar basin, and addition and recovery tests were performed, and values were between 81% and 120%. The precision was expressed with relative standard deviation (RSD) is less than 5%

Thesis (PhD (Chemical Engineering))--Cape Peninsula University of Technology, 2020 / The use of bioproducts in different commercial sectors such as medicine, agriculture, cosmetics, food, and chemical industries motivates the need for easy production and recovery techniques of bioproducts at laboratory and pilot scale. This study aims at the production and recovery of some selected bioproducts using supercritical fluid extraction techniques. Three products are chosen as case studies: these are ethanol, acetoin, and vanillin, since the ease of separation is influenced by the concentration of the product in the broth, these compounds were selected based on their concentration in the fermentation broth, according to literature sources. A standard method was developed in a spectrophotometer for quantifying the targeted product in the broth, while the product recovery studies was carried out using a supercritical fluid extraction pilot plant. Saccharomyces and Bacillus species were chosen for the bioproduction of the selected bioproducts. Experimental design and statistical analysis of results were carried out using response surface methodology (RSM) and artificial neural network (ANN). Studies on each of the selected bioproducts are as justified in the paragraphs below. Bioethanol production has recently become an increasing trend in research, with a focus on increasing its economic viability. Hence, the need to develop a low-cost fermentation medium with minimum redundant nutritional supplements, thereby minimizing the costs associated with nutritional supplements whereby inoculum preparation becomes necessary for ethanol production. Corn steep liquor (CSL) in glucose fermentation by Saccharomyces Type 1 (ST1) strain and Anchor Instant Yeast (AIY), which are low-cost media, are used as replacements for yeast extract (YE). The fermentation process parameters were optimized using artificial neural networks (ANN) and the response surface methodology (RSM). The study shows that for CSL, a maximum average ethanol concentration of 41.92 and 45.16 g/L representing 82% and 88% of the theoretical yield were obtained after 36 h of fermentation in a shake flask for ST1 and AIY respectively. For YE, ethanol concentration equivalent to 86% and 88% of theoretical yield were obtained with ST1 and AIY respectively after 48 h. Although, ANN predicted the responses of ethanol yield better than RSM, optimum conditions for ethanol production were better predicted by RSM. The consumers’ preference for ‘naturally’ produced aromas drives the development of bioproduction of acetoin from glucose with a view to optimize its production. The results revealed that by using a cheap nitrogen source, corn steep liquor, the yield of acetoin was similar to those of yeast and beef extracts. Furthermore, it was shown that by using Box-Behnken design, the optimum parameters such as glucose concentration, corn steep liquor, and inoculum size to maximize the concentration of acetoin produced were 78.40 g/L, 15.00% w/v and 2.70% v/v respectively. The validated concentration of acetoin produced in a triplicate analysis, 10.7 g/L, was 0.06% less than the predicted value. Increasing awareness of consumers of healthy, eco-friendly flavors and fragrances motivates the bioproduction of vanillin. The interactive effects of three variables on vanillin yield were evaluated by response surface methodology (RSM) with Box-Behnken design (BBD) model. The results showed the optimum conditions for the biotransformation of ferulic acid into vanillin can be achieved with maximum overall desirability (D) of 1.0 and a significant (p<0.05) quadratic model with regression coefficient (R2) of 0.995. Corn steep liquor, initial ferulic acid concentration and pH significantly influence the concentration of vanillin in the broth. The results in triplicate experiments confirmed vanillin yield of 386 mg/L after validation, which was in agreement with the prediction of the model. The maximum vanillin yield of 384.40 mg/L was predicted when corn steep liquor, ferulic acid concentration and pH were 7.72 g/L, 2.33 g/L, and 9.34 respectively. Fermentation system in a bioreactor has been proven to be an efficient system for the study of controlled fermentation variables when compared to a shake flask study. The influence of agitation, aeration, time and pH were analysed by Taguchi orthogonal array design for the upscale of acetoin in a bioreactor. The optimized parameters in 1.3L of fermentation vessel were as follows: 300 rpm agitation, 1.5 slpm aeration; 2 days’ fermentation time and 6.5 pH value. Agitation with above 70% was the most contributing factor and other variables were less than 30% in the percentage analysis of variance of each fermentation variables in the batch study of acetoin. A fourfold gain in acetoin titre (42.30 g/L) was obtained with the same substrate concentration in a lab-scale bioreactor on scaling up when compared with the shake flask batch study. The validated acetoin concentration of 41.72 g/L was obtained after a triplicate experiment to confirm the possibility of reproducing acetoin using the optimized conditions. Many separation techniques have been proven to recover value-added products from fermentation broth with a preference for several methods above other and new techniques that are emerging. Supercritical fluids separation using CO2 is one such technique. The feasibility of acetoin concentration and recovery was studied in supercritical CO2 pilot plant with pressure ranges of 100 to 300 bar, CO2 feed rate of 5 to 15 kg/h, at a process temperature of 37 and 80 °C in simulated and fermentation broth, respectively. The validated conditions for the fractionation of acetoin by supercritical fluid extraction (SFE) were determined as follows: extraction pressure, 300 bar; CO2 feed rate, 15 kg/h; extraction temperature 37 °C; and fractionation time of 30 minutes. At these operating conditions, the percentage recovery of acetoin with respect to the feed solution at the raffinate for the simulated and actual ermentation broth was 77.8% (0.20 g/L) and 77% (0.15 g/L) respectively. A two-fold extract increase was obtained after 30 minutes of fractionation. The study provides the technical feasibility and the base case data which are critical to the development and design of processes for production and recovery of acetoin. The lesson gleaned from this study may be extended to develop processes for the production and recovery of other bioproducts (ethanol and vanillin).

One of the main problems encountered in chemical analysis operations in the field is collecting sufficient sample from the source and transferring that sample to the measurement instrument for fast separation and identification. I have been involved in developing a field-portable gas chromatography-mass spectrometry (GC-MS) system with solid phase microextraction (SPME) sampling for point detection of chemical agents. The objective is to minimize the analysis time between sampling and detection of a potential chemical threat. SPME offers a convenient means for sampling gaseous and liquid samples, concentrating the analytes, and transferring the analytes to the injection port of a GC system for separation and identification. GC-MS has advantages of high efficiency, speed, and applicability for field analysis. Work was done to optimize the SPME fiber coating, capillary column dimensions, and GC operating conditions to provide complete analysis within 3 minutes. Since isothermal operation of the GC was a prior requirement, many components in the chromatograms were unresolved. Therefore, a peak de-convolution algorithm was applied to allow for identification and quantitation of poorly resolved and often completely obscured trace components. Details of the instrumentation and optimization of operating conditions are described in this thesis.

Furthering our understanding of the physics of flapping flight has the potential to benefit the field of micro air vehicles. Advancements in micro air vehicles can benefit applications such as surveillance, reconnaissance, and search and rescue. In this research, flapping kinematics of a ladybug was explored using a direct linear transformation. A flapping mechanism design is presented that was capable of executing ladybug or other species-specific kinematics. The mechanism was based on a differential gear design, had two wings, and could flap in harsh environments. This mechanism served as a test bed for force analysis and optimization studies. The first study was based on a Box-Behnken screening design to explore wing kinematic parameter design space and manually search in the direction of flapping kinematics that optimized the objective of maximum combined lift and thrust. The second study used a Box-Behnken screening design to build a response surface. Using gradient-based techniques, this surface was optimized for maximum combined lift and thrust. Box-Behnken design coupled with response surface methodology was an efficient method for exploring the mechanism force response. Both methods for optimization were capable of successfully improving lift and thrust force outputs. The incorporation of the results of these studies will aid in the design of more efficient micro air vehicles and with the ultimate goal of leading to a better understanding of flapping wing aerodynamics and the development of aerodynamic models.

Flapping flight shows promise for micro air vehicle design because flapping wings provide superior aerodynamic performance than that of fixed wings and rotors at low Reynolds numbers. In these flight regimes, unsteady effects become increasingly important. This thesis explores some of the unsteady effects that provide additional lift to flapping wings through an experiment-based optimization of the kinematics of a flapping wing mechanism in a water tunnel. The mechanism wings and flow environment were scaled to simulate the flight of the hawkmoth (Manduca sexta) at hovering or near-hovering speeds. The optimization was repeated using rigid and flexible wings to evaluate the impact that wing flexibility has on aerodynamic performance of flapping wings. The trajectories that produced the highest lift were compared using particle image velocimetry to characterize the flow features produced during the periods of peak lift. A leading edge vortex was observed with all of the flapping trajectories and both wing types, the strength of which corresponded to the measured amount of lift of the wing. This research furthers our understanding of the lift-generating mechanisms used in nature and can be applied to improve the design of micro air vehicles.