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.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / RESUMO O presente trabalho propÃs investigar a tecnologia de eletrocoagulaÃÃo (EC) para o tratamento de efluente tÃxtil utilizando corrente contÃnua pulsada (CCP) e eletrodos de aÃo inoxidÃvel 304. O efluente utilizado foi coletado em uma indÃstria tÃxtil fabricante de redes localizada no municÃpio de Jaguaruana-CE. A Metodologia de SuperfÃcie de Resposta Box-Behnken foi utilizada para analisar e otimizar as condiÃÃes operacionais, visando a mÃxima remoÃÃo de cor, turbidez e demanda quÃmica de oxigÃnio (DQO) do efluente tÃxtil. Os experimentos foram realizados com um volume reacional de 2,6 L, em modo batelada. A cinÃtica de degradaÃÃo de DQO foi estudada atravÃs do ajuste de regressÃo nÃo linear, obedecendo ao modelo de cinÃtica de segunda ordem. Diante dos resultados obtidos a configuraÃÃo Ãtima considerada foi: velocidade de agitaÃÃo=200 rpm, frequÃncia dos pulsos elÃtricos=1000 Hz e espaÃamento entre os eletrodos=1 mm, em 50 minutos de EC. Nestas condiÃÃes foram obtidas remoÃÃes de cor, turbidez e DQO, respectivamente de 98,94%, 85,87% e 81,23%, adequando o valor de DQO ao padrÃo de lanÃamento exigido pela Portaria n 154/2002 da SuperintendÃncia Estadual do Meio Ambiente (SEMACE). Em adiÃÃo, verificou-se que o processo de EC tambÃm foi eficaz para a reduÃÃo de sÃlidos suspensos totais, nitrogÃnio total, sulfato e sulfeto, como tambÃm para a reduÃÃo da toxicidade aguda frente à Lactuca sativa, elevando os valores do Ãndice de Crescimento Relativo (ICR) e Ãndice de GerminaÃÃo (IG) inicialmente registrados para o efluente bruto. A concentraÃÃo de Ãons cloreto nÃo decresceu durante a EC, apresentando-se como um aspecto favorÃvel para a reutilizaÃÃo do efluente tratado no prÃprio processo produtivo tÃxtil, o qual demanda uma elevada concentraÃÃo de cloreto de sÃdio (NaCl). / The present work proposed to investigate the electrocoagulation technology (EC) for the treatment of textile effluent using pulsed direct current (CCP) and stainless steel electrodes 304. The effluent used was collected in a textile manufacturer networks in the municipality of Jaguaruana -CE. The Response Surface Methodology Box-Behnken was used to analyze and optimize the operating conditions, aimed at maximum removal of color, turbidity and chemical oxygen demand (COD) of the textile effluent. The experiments were performed with a reaction volume of 2.6 L in batch mode. The COD degradation kinetics was studied using non-linear regression fit, according to the second order kinetics model. Based on these results the optimal configuration was considered: agitation speed = 200 rpm, frequency of electrical pulses = 1000 Hz and spacing between electrodes = 1 mm, in 50 minutes of EC. Under these conditions color removals were obtained, turbidity and COD, respectively 98.94%, 85.87% and 81.23%, adjusting the COD value to discharge standard required by Ordinance No. 154/2002 of the State Superintendent of Half Environment (SEMACE). In addition, it was found that the CS process is also effective for reduction of total suspended solids, total nitrogen, sulfide and sulfate, as well as for the reduction of acute toxicity Lactuca sativa forward, raising the value of the Growth Index Relative (ICR) and germination index (GI) initially recorded for the raw wastewater. The concentration of chloride ions has not decreased during the EC, presenting itself as a favorable aspect for the reuse of treated effluent in own textile production process, which demands a high concentration of sodium chloride (NaCl).

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.

Though still in relative infancy, the field of flapping flight has potential to have a far-reaching impact on human life. Nature presents a myriad of examples of successful uses of this locomotion. Human efforts in flapping flight have seen substantial improvement in recent times. Wing kinematics are a key aspect of this study. This study summarizes previous wing trajectory generators and presents a new trajectory generation method built upon previous methods. This includes a novel means of commanding unequal half-stroke durations subject to robotic trajectory continuity requirements. Additionally, previous optimization methods are improved upon. Experimental optimization is performed using the new trajectory generation method and a more traditional means. Methods for quantifying and compensating for sensor time-dependence are also discussed. Results show that the Polar Fourier Series trajectory generator advanced rapidly through the optimization process, especially during the initial phase of experimentation. The Modified Berman and Wang trajectory generator moved through the design space more slowly due to the increased number of kinematic parameters. When optimizing lift only, the trajectory generators produced similar results and kinematic forms. The findings suggest that the objective statement should be modified to reward efficiency while maintaining a certain amount of lift. It is expected that the difference between the capabilities of the two trajectory generators will become more apparent under such conditions.

[pt] Metal Organic Frameworks(MOFs) são compostos de coordenação que possuem íons ou clusters metálicos ligados a espécies orgânicas, formando uma rede porosa, cristalina e de elevada área superficial. Essas características despertaram interesse no desenvolvimento de materiais oriundos de MOFs e, possivelmente, utilizá-los como catalisadores na produção de combustíveis líquidos. Nesta pesquisa, a síntese do Co-MOF-71 foi realizada pelo método solvotérmico, misturando ácido tereftálico, obtido a partir da despolimerização por hidrólise alcalina do polietileno tereftalato (PET) reciclável, e nitrato de cobalto hexahidratado, em solução de N,N-dimetilformamida, etanol e água. Após reação a temperatura de 110, 130 e 150 graus C, o material foi caracterizado quanto a sua resistência térmica, através da análise termogravimétrica, a cristalinidade, na análise de difração de raios X, e, de forma qualitativa, a composição elementar, avaliada na análise de microscopia eletrônica de varredura com energia dispersiva. O planejamento de experimentos de Box-Behnken foi elaborado, variando-se três fatores (temperatura, concentração de ácido tereftálico e quantidade de cobalto), totalizando quinze reações. A Co-MOF-71 foi calcinada em atmosfera inerte de N2 a 500 graus C para gerar uma matriz carbônica contendo cobalto, da qual a área superficial específica foi medida por adsorção-dessorção de N2, aplicando-se o método de Brunauer-Emmett-Teller. Um modelo polinomial de segunda ordem foi aplicado, com sua respectiva análise de variância (ANOVA) e os efeitos das variáveis de entrada foram classificados, constatando que a temperatura não exerceu influência significativa na faixa aplicada. Em seguida, o modelo foi atualizado, atingindo coeficiente de determinação (R2) de 87,39 por cento, revelando o teor de ácido tereftálico como o efeito mais expressivo. Além disso, a superfície de resposta confirmou que o cenário de maior área superficial é alcançado ao adicionar excesso de ligante orgânico no sistema, consistente com o melhor resultado experimental (82 m2.g-1). / [en] MOFs (Metal-organic frameworks) are special compounds that can be an interesting alternative for heterogeneous catalysis, due their singularities like a porous and crystalline structure with high specific area. This work proposes an environmentally favorable production route of Co-MOF-71 derived material, starting with the depolymerization of PET from plastic waste to obtain terephthalic acid, which is the source of ligand BDC (1,4-benzenodicarboxylate). The synthesis of Co-MOF-71 was performed by solvothermal method and, optimizing the research, Box-Behnken design were developed with three independent variables: amount of terephthalic acid, cobalt content, and temperature. The samples were characterized by XRD, TGA, and SEM analysis before and after calcination at 500 degrees C. Finally, the specific surface area was measured by N2 adsorption-desorption, and a second-order polynomial model was suggested, with its respective analysis of variance (ANOVA), indicating that temperature has no significant influence in the applied range. Then, the model was updated, reaching the coefficient of determination (R2 ) of 87.39 percent and presenting the terephthalic acid content as the most relevant effect. Additionally, the response surface confirmed the scenario of higher surface area with excess BDC in the system, consistent with the best experimental result (82 m2 / g).

Cellulose nanocrystals (CNCs) are frequently prepared by sulfuric acid hydrolysis of a purified cellulose starting material. CNC yields, however, are generally low, often below 20%. This study employs response surface methodology to optimize the hydrolysis conditions for maximum CNC yield. Two experimental designs were tested and compared: the central composite design (CCD) and the Box–Behnken design (BBD). The three factors for the experimental design were acid concentration, hydrolysis temperature, and hydrolysis time. The responses quantified were CNC yield, sulfate group density, ζ-potential, z-average diameter, and Peak 1 value. The CCD proved suboptimal for this purpose because of the extreme reaction conditions at some of its corners, specifically (1,1,1) and (–1,–1, –1). Both models predicted maximum CNC yields in excess of 65% at similar sulfuric acid concentrations (~59 wt %) and hydrolysis temperatures (~65 °C). With the BBD, the hydrolysis temperature for maximum yield lay slightly outside the design space. All three factors were statistically significant for CNC yield with the CCD, whereas with the BBD, the hydrolysis time in the range 60–150 min was statistically insignificant. With both designs, the sulfate group density was a linear function of the acid concentration and hydrolysis temperature and maximal at the highest acid concentration and hydrolysis temperature of the design space. Both designs showed the hydrolysis time to be statistically insignificant for the ζ-potential of CNCs and yielded potentially data-overfitting regression models. With the BBD, the acid concentration significantly affected both the z-average diameter and Peak 1 value of CNCs. However, whereas the z-average diameter was more strongly affected by the hydrolysis temperature than the hydrolysis time, the Peak 1 value was more strongly affected by the hydrolysis time. The CCD did not yield a valid regression model for the Peak 1 data and a potentially data-overfitting model for the z-average diameter data. A future optimization study should use the BBD but slightly higher hydrolysis temperatures and shorter hydrolysis times than used with the BBD in this study (45–65 °C and 60–150 min, respectively). / Master of Science

The methodology of the design of experimnet has become an integral part of the optimisation of manufacturing processes in recent decades. Problems regarding designs of experiments are still up to date, especially because of a variety of approaches to collecting and evaluating data. Scientists in different research and development areas often do not take into account possible shortcommings or even essential assumptions of selected design and/or its evaluation methods. This disertation thesis summarizes theoretical bases of selected designs of experiments. Describes several applications of central composite design on responses regarding wire electrical discharge machining process. And compares different designs of experiment for response surfaces of five parameters with regards to algoritmic selection of statistically signifficant parameters.