The Physical Vapour Deposition (PVD) magnetron sputtering process is one of the widely used techniques for depositing thin film coatings on substrates for various applications such as integrated circuit fabrication, decorative coatings, and hard coatings for tooling. In the area of coatings on cutting tools, tool life can be improved drastically with the application of hard coatings. Application of coatings on cutting tools for various machining techniques, such as continuous and interrupted cutting, requires different coating characteristics, these being highly dependent on the process parameters under which they were formed. To efficiently optimise and customise the deposited coating characteristics, PVD process modelling using RSM methodology was proposed. The aim of this research is to develop a PVD magnetron sputtering process model which can predict the relationship between the process input parameters and resultant coating characteristics and performance. Response Surface Methodology (RSM) was used, this being one of the most practical and cost effective techniques to develop a process model. Even though RSM has been used for the optimisation of the sputtering process, published RSM modelling work on the application of hard coating process on cutting tool is lacking. This research investigated the deposition of TiAlN coatings onto tungsten carbide cutting tool inserts using PVD magnetron sputtering process. The input parameters evaluated were substrate temperature, substrate bias voltage, and sputtering power; the out put responses being coating hardness, coating roughness, and flank wear (coating performance). In addition to that, coating microstructures were investigated to explain the behaviour of the developed model. Coating microstructural phenomena assessed were; crystallite grain size, XRD peak intensity ratio I111/I200 and atomic number percentage ratio of Al/Ti. Design Expert 7.0.3 software was used for the RSM analysis. Three process models (hardness, roughness, performance) were successfully developed and validated. The modelling validation runs were within the 90% prediction interval of the developed models and their residual errors compared to the predicted values were less than 10%. The models were also qualitatively validated by justifying the behaviour of the output responses (hardness, roughness, and flank wear) and microstructures (Al/Ti ratio, crystallographic peak ratio I111/1200, and grain size) with respect to the variation of the input variables based on the published work by researchers and practitioners in this field. The significant parameters that influenced the coating hardness, roughness, and performance (flank wear) were also identified. Coating hardness was influenced by the substrate bias voltage, sputtering power, and substrate temperature; coating roughness was influenced by sputtering power and substrate bias; and coating performance was influenced by substrate bias. The analysis also discovered that there was a significant interaction between the substrate temperature and the sputtering power which significantly influenced coating hardness, roughness, and performance; this interaction phenomenon has not been reported in previously published literature. The correlation study between coating characteristics, microstructures and the coating performance (flank wear) suggested that the coating performance correlated most significantly to the coating hardness with Pearson coefficient of determination value (R2) of 0.7311. The study also suggested some correlation between coating performance with atomic percentage ratio of Al/Ti and grain size with R2 value of 0.4762 and 0.4109 respectively.

Des agrégats à base des boues de phosphate de la zone de Gantour ( Youssoufia,Maroc) sont cuits à des températures comprises entre 900 et 1200°C, et examinés par différentes techniques (DRX, MEB, analyses thermique et dilatométrique, et spectroscopie d’impédance). Les propriétés physiques des agrégats (retrait, absorption d’eau et résistance à la compression) sont mesurées et corrélées, dans certains cas, aux facteurs expérimentaux(température, temps de cuisson, teneur de l’additif), et ce en utilisant la méthodologie de la recherche expérimentale.Les agrégats amendés à l’argile smectitique sont le siège de formation de la gehlénite. Dans ce cas, la fluorapatite a partiellement résisté au traitement thermique, et a été le siège d’une ségrégation localisée. Les mesures d'impédance ont bien mis en évidence l'étape principale du frittage, lequel s’est produit par écoulement de la masse fondue. En se basant sur les valeurs de la densité, les granulats cuits à 900 et à 1100°C pouvaient bien être considérés comme des agrégats légers.Les études menées sur les agrégats des mélanges : argile kaolinitique-boue, cendre boue,et argile kaolinitique-cendre-boue ont montré la présence de la labradorite, et d’une masse fondue, qui semblait se former, entre autres, de la fusion de la fluorapatite. Par ailleurs,l'utilisation de la méthodologie de la recherche expérimentale a permis d'évaluer le poids des effets des facteurs expérimentaux sur les propriétés physiques des agrégats. Des granulats légers (1,02 < densité < 2,1 g/cm3) et résistants sont préparés avec succès dans les conditions expérimentales adoptées. Les granulats ayant le meilleur rapport résistance / densité sont ceux du mélange ternaire.Concernant le volet application, les résultats ont montré que l’utilisation des agrégats en construction est possible et que l’association d’agrégats légers au sol a permis d’activer la croissance des plants de la luzerne. D’un autre côté, l'absorption du phosphore par les racines(1,45 mg/g maximum) des plantes était meilleure dans le cas du mélange contenant de l’argile. / Phosphate sludge generated from beneficiation plants of Moroccan phosphate rocks was investigated at the range [900-1200°C] by X-ray diffraction, scanning electron microscopy, thermal analysis dilatometric analysis and impedance spectroscopy. Mixtures of the phosphates ludge and amendments such as a swelling clay (up to 30 wt.% of the clay), a kaolinitic clay (up to 40 wt.% of the sludge) and a fly ash (65.5 wt.% of the ash) were investigated and their properties (shrinkage, density, water absorption and compressive strength) were measured as a function of temperature and clay addition. The results showed that gehlénite neoformed from lime of decomposed carbonates and breakdown products of clay minerals in the first mixture while labradorite/anorthite was the only neoformed phase in the other blends. Also fluoroapatite (original mineral) resisted heating until fusion in almost samples. A new approach based on the methodology of the experimental design was adopted to assess the effect of the processing factors on the studied properties. The measured properties were mainly controlled by temperature, and the effect of clay addition was less regular. Considering the mixtures densities lightweight agglomerates can be produced at specific conditions. On the other hand, the release ability of phosphorus by LWAs in the presence ofalfalfa plants has been performed. It was found that due to the release of phosphorus by soil embedded pellets the growth of alfalfa plants improved. The sintering process of blends of phosphate sludge and a naturally occurring clay material (0-30 wt.%) was investigated in the range 650-1100°C by using impedance spectroscopy. The results showed that the sintering process was effective between 750 and 1000°C and occurred by melt flow.

A estabilidade oxidativa em óleos e emulsões é influenciada pela ação simultânea de diversos fatores. Entretanto, a avaliação do efeito antioxidante de novos compostos tem sido conduzida utilizando-se valores fixos para esses fatores. Portanto, o objetivo deste estudo foi aplicar técnicas fatoriais para desenvolver modelos de oxidação lipídica nos quais os principais fatores pudessem variar simultaneamente. A oxidação de óleo de linhaça removido de seus componentes minoritários, determinada pela concentração de hidroperóxidos e malonaldeído (TBARS), foi avaliada em função da variação conjunta da temperatura (40 - 60 oC), concentração de ferro (0,0 - 1,0 mmol/L FeSO47H2O) e de ascorbil palmitato (0,0 - 1,5 mmol/L). Os maiores valores observados para os marcadores foram obtidos a 40oC, sendo altamente dependentes da relação \"ferro / ascorbil palmitato\". Adicionando-se 1,4707 mmol/L de ferro e 1,5839 mmol/L de ascorbil palmitato, a amplitude de formação de hidroperóxidos aumentou em 57%. Uma emulsão foi preparada com 1% do mesmo óleo de linhaça removido de seus componentes minoritários, utilizando-se um emulsificante aniônico sob alta pressão. A variação da temperatura, pH e concentração de ferro, cobre, ácido ascórbico, ascorbil palmitato e cloreto de sódio nos marcadores químicos da oxidação (hidroperóxidos e TBARS) foi avaliada através de um planejamento fracionário do tipo Plackett-Burman para seleção de variáveis. A seguir, o efeito das concentrações de ferro (0,0 - 1,0 mmol/L FeSO47H2O), ácido ascórbico (0,0 - 2,0 mmol/L) e pH (3,0 - 7,0) na estabilidade oxidativa das emulsões foi avaliado utilizando-se um Delineamento Composto Central. Os maiores valores dos marcadores foram obtidos adicionando-se 0,885 mmol/L de ferro e 1,700 mmol/L de ácido ascórbico à emulsão mantida a 30ºC sob pH 5,51. A atividade antioxidante de seis compostos foi avaliada em ambos os modelos (óleo puro e emulsão), sendo que uma melhor discriminação entre as amostras foi observada nos sistemas otimizados. A utilização de técnicas fatoriais mostrou-se eficiente na avaliação conjunta de vários fatores que influenciam a estabilidade oxidativa de óleos e emulsões, e proporcionou um melhor poder de discriminação na atividade antioxidante de compostos naturais e artificiais. / The oxidative stability in bulk oils and emulsions is affected by many factors. However, assessment of the antioxidant effect of new compounds has been carried out under fixed conditions. Thus, the objective of this study was to apply factorial techniques to develop lipid oxidation models in which the main factors vary simultaneously. Oxidation of flaxseed oil stripped of its minor components determined by the concentration of hydroperoxides and malonaldehyde (TBARS) was evaluated according to the combined variation of temperature (40 - 60 oC), iron concentration (0,0 - 1,0 mmol/L FeSO47H2O) and ascorbyl palmitate concentration (0,0 - 1,5 mmol/L). The highest observed values to these markers were obtained at 40oC, being greatly dependent on the \"iron / ascorbyl palmitate\" ratio. Addition of 1,4707 mmol/L of iron and 1,5839 mmol/L of ascorbyl palmitate increased the hydroperoxide formation by 57%. An emulsion was prepared with 1% of the same stripped flaxseed oil and an anionic emulsifier under high pressure. The variation of temperature, pH and iron, copper, ascorbic acid, ascorbyl palmitate and sodium chloride concentration on the chemical markers of oxidation (hydroperoxides and TBARS) was evaluated using a Plackett-Burman design to screen the variables. Following, the effect of iron concentration (0,0 - 1,0 mmol/L FeSO47H2O), ascorbyl palmitate concentration (0,0 - 2,0 mmol/L) and pH (3.0 - 7,0) on the oxidative stability of the emulsion was evaluated using a Central Composite Design. The highest observed values to these markers were obtained adding 0,885 mmol/L of iron and 1,700 mmol/L of ascorbic acid to the emulsion under 30ºC and pH 5,51. The antioxidant activity of six compounds was evaluated using both models (bulk oil and emulsion), in which a better discrimination was observed for the samples in the optimized systems. The application of factorial techniques was efficient on the joint assessment of several factors that affect the oxidative stability of oils and emulsions, and provided a better discrimination power on the antioxidant activity of natural and artificial compounds.

Made available in DSpace on 2014-06-11T19:31:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-03Bitstream added on 2014-06-13T20:21:44Z : No. of bitstreams: 1 ernandes_fmpg_dr_sjrp.pdf: 1963066 bytes, checksum: 42dcae2ecfe9dfb358788c6490a13653 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal produto da fermentação de açúcares por Zymomonas mobilis é o etanol quando glicose e frutose são utilizadas como fontes de carbono. Entretanto, quando sacarose é empregada na fermentação, o rendimento do etanol diminui devido à formação de subprodutos como levana, sorbitol, acetaldeído, ácido acético, pequenas quantidades de alguns álcoois superiores e fenol. A utilização de produtos agroindustriais, como o caldo e melaço de cana-deaçúcar, é uma alternativa para reduzir o custo final dos produtos de fermentação devido à disponibilidade de aquisição e composição química desses substratos. Este trabalho teve como objetivo utilizar substratos alternativos e otimizar as condições de fermentação para a produção de etanol, levana e sorbitol por Zymomonas mobilis CCT 4494. Também foi considerado o efeito da variação do substrato e de sais minerais adicionados nos meios de produção (sintético, caldo e melaços de cana-de-açúcar). Para a obtenção dos produtos de fermentação, foi aplicada a metodologia de superfície de resposta, seguindo um planejamento fatorial do tipo 27-2, de acordo com o modelo proposto por Box e Hunter, onde as variáveis independentes estudadas foram: pH inicial do meio de cultivo, temperatura de incubação, concentração do substrato e efeito da adição de KCl, K2SO4, MgSO4, CaCl2. Durante a realização das fermentações foi observado que a bactéria Zymomonas mobilis CCT 4494 se adaptou nos meios de fermentação contendo altas concentrações de sacarose e suportou a variação do pH e da temperatura de fermentação. O aumento da concentração da fonte de carbono favoreceu a formação dos produtos levana e etanol, entretanto, não houve produção de sorbitol. O meio sintético proporcionou maior rendimento de levana e etanol, enquanto que, os meios alternativos caldo e melaços de cana-de-açúcar... / The main product from fermentation of sugars by Zymomonas mobilis is ethanol when glucose and fructose are used as carbon sources. However, when sucrose is used in the fermentation medium, ethanol yield decreases due to the formation of by-products such as levan, sorbitol, acetaldehyde, acetic acid, small amounts of some superior alcohols and phenol. The use of agro industrial by products, such as sugarcane juice and molasses, is an alternative to reduce the final cost of fermentation products due to the constant availability and to the chemical composition of these by substrates. This study had the aim of using alternative substrates and of optimizing fermentation conditions for the production of ethanol, levan and sorbitol by Zymomonas mobilis CCT 4494. The effect of variation of substrate and mineral salts added to the production media (synthetic, sugarcane juice and molasses) was also considered. To obtain the fermentation products, response surface methodology was employed, following a 27-2 factorial planning, according to the model proposed by Box and Hunter, where the independent variables studied were: initial medium pH, incubation temperature, substrate concentration and effect of the addition of KCl, K2SO4, MgSO4, CaCl2. During the fermentations, it was noted that the bacteria Zymomonas mobilis CCT 4494 well adapted in the media containing high concentrations of sucrose and tolerated pH and temperature variations. The increase of carbon source concentration favored the formation of levan and ethanol, however, there was no sorbitol production. The synthetic medium offered higher levan and ethanol yield, whereas alternative media sugarcane juice and molasses, favored cellular growth. Among the independent variables analyzed with the best medium (synthetic) for biosynthesis of the biopolymer and ethanol, the ones that significantly (p<0.05) affected were KCl, K2SO4, CaCl2... (Complete abstract click electronic access below)

A estabilidade oxidativa em óleos e emulsões é influenciada pela ação simultânea de diversos fatores. Entretanto, a avaliação do efeito antioxidante de novos compostos tem sido conduzida utilizando-se valores fixos para esses fatores. Portanto, o objetivo deste estudo foi aplicar técnicas fatoriais para desenvolver modelos de oxidação lipídica nos quais os principais fatores pudessem variar simultaneamente. A oxidação de óleo de linhaça removido de seus componentes minoritários, determinada pela concentração de hidroperóxidos e malonaldeído (TBARS), foi avaliada em função da variação conjunta da temperatura (40 - 60 oC), concentração de ferro (0,0 - 1,0 mmol/L FeSO47H2O) e de ascorbil palmitato (0,0 - 1,5 mmol/L). Os maiores valores observados para os marcadores foram obtidos a 40oC, sendo altamente dependentes da relação \"ferro / ascorbil palmitato\". Adicionando-se 1,4707 mmol/L de ferro e 1,5839 mmol/L de ascorbil palmitato, a amplitude de formação de hidroperóxidos aumentou em 57%. Uma emulsão foi preparada com 1% do mesmo óleo de linhaça removido de seus componentes minoritários, utilizando-se um emulsificante aniônico sob alta pressão. A variação da temperatura, pH e concentração de ferro, cobre, ácido ascórbico, ascorbil palmitato e cloreto de sódio nos marcadores químicos da oxidação (hidroperóxidos e TBARS) foi avaliada através de um planejamento fracionário do tipo Plackett-Burman para seleção de variáveis. A seguir, o efeito das concentrações de ferro (0,0 - 1,0 mmol/L FeSO47H2O), ácido ascórbico (0,0 - 2,0 mmol/L) e pH (3,0 - 7,0) na estabilidade oxidativa das emulsões foi avaliado utilizando-se um Delineamento Composto Central. Os maiores valores dos marcadores foram obtidos adicionando-se 0,885 mmol/L de ferro e 1,700 mmol/L de ácido ascórbico à emulsão mantida a 30ºC sob pH 5,51. A atividade antioxidante de seis compostos foi avaliada em ambos os modelos (óleo puro e emulsão), sendo que uma melhor discriminação entre as amostras foi observada nos sistemas otimizados. A utilização de técnicas fatoriais mostrou-se eficiente na avaliação conjunta de vários fatores que influenciam a estabilidade oxidativa de óleos e emulsões, e proporcionou um melhor poder de discriminação na atividade antioxidante de compostos naturais e artificiais. / The oxidative stability in bulk oils and emulsions is affected by many factors. However, assessment of the antioxidant effect of new compounds has been carried out under fixed conditions. Thus, the objective of this study was to apply factorial techniques to develop lipid oxidation models in which the main factors vary simultaneously. Oxidation of flaxseed oil stripped of its minor components determined by the concentration of hydroperoxides and malonaldehyde (TBARS) was evaluated according to the combined variation of temperature (40 - 60 oC), iron concentration (0,0 - 1,0 mmol/L FeSO47H2O) and ascorbyl palmitate concentration (0,0 - 1,5 mmol/L). The highest observed values to these markers were obtained at 40oC, being greatly dependent on the \"iron / ascorbyl palmitate\" ratio. Addition of 1,4707 mmol/L of iron and 1,5839 mmol/L of ascorbyl palmitate increased the hydroperoxide formation by 57%. An emulsion was prepared with 1% of the same stripped flaxseed oil and an anionic emulsifier under high pressure. The variation of temperature, pH and iron, copper, ascorbic acid, ascorbyl palmitate and sodium chloride concentration on the chemical markers of oxidation (hydroperoxides and TBARS) was evaluated using a Plackett-Burman design to screen the variables. Following, the effect of iron concentration (0,0 - 1,0 mmol/L FeSO47H2O), ascorbyl palmitate concentration (0,0 - 2,0 mmol/L) and pH (3.0 - 7,0) on the oxidative stability of the emulsion was evaluated using a Central Composite Design. The highest observed values to these markers were obtained adding 0,885 mmol/L of iron and 1,700 mmol/L of ascorbic acid to the emulsion under 30ºC and pH 5,51. The antioxidant activity of six compounds was evaluated using both models (bulk oil and emulsion), in which a better discrimination was observed for the samples in the optimized systems. The application of factorial techniques was efficient on the joint assessment of several factors that affect the oxidative stability of oils and emulsions, and provided a better discrimination power on the antioxidant activity of natural and artificial compounds.

<p>Cilj ovog rada je ispitivanje uticaja procesnih<br />parametara (transmembranski pritisak, protok i<br />koncentracija suspenzije) na vrednost fluksa<br />permeata, sa i bez prisustva statičkog me&scaron;ača,<br />tokom procesa mikrofiltracije suspenzija<br />p&scaron;eničnog skroba na keramičkim membranama<br />različitih veličina pora (200 nm i 500 nm).<br />Mikrofiltracija je izvođena u uslovima<br />recirkulacije i koncentrisanja napojne suspenzije.<br />Za modelovanje zavisnosti procesa mikrofiltracije<br />suspenzija skroba od procesnih parametara<br />primenjen je postupak odzivne povr&scaron;ine.<br />Ispitivanjem mikrofiltracije suspenzija p&scaron;eničnog<br />skroba na membranama sa različitim srednjim<br />prečnikom pora (200 i 500 nm) uočeno je da sa<br />povećanjem veličine pora vrednost fluksa<br />permeata opada.<br />U posmatranom eksperimentalnom opsegu<br />procesnih parametara postignuto je relativno<br />povećanje stacionarnog fluksa od 25% do 50% u<br />uslovima recirkulacije napojne suspenzije, dok je<br />u uslovima koncentrisanja napojne suspenzije<br />relativno povećanje srednjeg fluksa iznosilo od<br />20% do 80%. Porast fluksa do kojeg dolazi<br />postavljanjem statičkog me&scaron;ača u kanal membrane</p><p>uslovljen je uspostavljanjem turbulentnih uslova<br />proticanja i karakterističnog kretanja fluida duž<br />kanala membrane, koja je posledica<br />karakterističnog povezivanja helikoidnih<br />elemenata Kenics statičkog me&scaron;ača.<br />Kako u uslovima recirkulacije napojne sme&scaron;e,<br />tako i u uslovima koncentrisanja, vrednost<br />relativne specifične potro&scaron;nje energije zavisi skoro<br />isključivo od vrednosti protoka napojne sme&scaron;e. Sa<br />povećanjem protoka specifična potro&scaron;nja energije<br />u prisustvu statičkog me&scaron;ača naglo raste i<br />relativno povećanje protoka nije dovoljno da bi<br />kompenzovalo gubitak hidrauličke snage. U<br />opsegu protoka od 80 do 100 L/h su obezbeđene<br />pozitivne vrednosti relativne promene specifične<br />potro&scaron;nje energije, te je upotreba statičkog me&scaron;ača<br />opravdana sa ekonomskog aspekta.<br />Optimizacija eksperimentalnih uslova urađena je<br />postupkom istovremene maksimizacije fluksa<br />permeata u sistemima sa statičkim me&scaron;ačem i<br />relativne promene specifične potro&scaron;nje energije.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />recirkulacije napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri maksimalnoj<br />vrednosti transmembranskog pritiska od 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 6 g/L.<br />Optimalni uslovi izvođenja procesa mikrofiltracije<br />suspenzija p&scaron;eničnog skroba u uslovima<br />koncentrisanja napojne suspenzije ukazuju da je<br />proces potrebno izvoditi pri vrednosti<br />transmembranskog pritiska od 0,85 do 0,9 bara,<br />protocima od 85 do 100 L/h i koncentraciji od 5<br />do 7 g/L.<br />Pored ispitivanja na laboratorijskoj<br />aparaturi, cilj ovog rada je bio i ispitivanje uticaja<br />procesnih parametara na proces mikrofiltracije<br />suspenzija skroba u poluindustrijskim uslovima<br />(na jednokanalnoj i vi&scaron;ekanalnoj membrani<br />srednjeg prečnika pora 200 nm), odnosno &scaron;ireg<br />opseg vrednosti transmembranskog pritiska i<br />protoka suspenzije na pomenute odzive u<br />uslovima koncentrisanja napojne suspenzije.</p> / <p> The aim of this study was to investigate the effect of<br /> process parameters (transmembrane pressure, flow<br /> rate and suspension concentration) on the permeate<br /> flux in the system with and without the presence of<br /> static mixer. Microfiltration of wheat starch<br /> suspensions was performed in recirculation and<br /> concentration mode using ceramic membranes with<br /> different pore size (200 nm and 500 nm). Response<br /> surface methodology was applied for modeling<br /> cross-flow microfiltration of starch suspensions.<br /> During investigation of starch suspension<br /> microfiltration process on membranes with different<br /> pore size diameter (200 and 500 nm) it was<br /> observed that with increasing pore size the permeate<br /> flux declined.<br /> In the experimental range of process parameters,<br /> flux increase had values between 25% and 50% in<br /> recirculation mode, while in concentration mode<br /> this improvement was in range between 20% and 80%. The increase in flux that occurs by placing a</p> <p> static mixer in the membrane channel was caused<br /> by the establishment of turbulent flow conditions<br /> and the characteristic flow of fluid along the<br /> membrane channel, which is a consequence of the<br /> characteristic geometry of Kenics static mixer.<br /> Both in recirculation and concentration mode, the<br /> reduction of specific energy consumption depends<br /> almost exclusively on the value of the suspension<br /> flow rate. Specific energy consumption increased<br /> rapidly with increasing flow rate in the presence of<br /> static mixers and flux improvement is not high<br /> enough to compensate the loss of hydraulic<br /> dissipated power. The flow rate in the range from<br /> 80 to 100 L/h provided positive values of the<br /> reduction of specific energy consumption and the<br /> use of static mixers was justified from the<br /> economical point of view.<br /> Optimization of experimental conditions was done<br /> by a procedure of simultaneous maximization of<br /> permeate flux in systems with static mixers and<br /> reduction of specific energy consumption. Optimal<br /> conditions of the wheat starch suspension<br /> microfiltration in recirculation mode indicate that<br /> the process should be conducted at the maximum<br /> value of transmembrane pressure of 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 6<br /> g/L.<br /> Optimal conditions of the wheat starch suspension<br /> microfiltration in concentration mode indicate that<br /> the process should be conducted when the value of<br /> transmembrane pressure from 0.85 to 0.9 bar, flow<br /> rates from 85 to 100 L/h and concentration of 5 to 7<br /> g/L.<br /> Apart from investigations in laboratory conditions,<br /> the aim of this study was to examine the influence<br /> of process parameters on the starch suspensions<br /> microfiltration in the pilot plant (one channel and<br /> multichannel membrane with pore diameter 200<br /> nm) and wider range of transmembrane pressure<br /> and suspension flow rate on the mentioned<br /> responses in concentration mode.</p>

Modern engineering design tends to use computer simulations such as Finite Element Analysis (FEA) to replace physical experiments when evaluating a quality response, e.g., the stress level in a phone packaging process. The use of computer models has certain advantages over running physical experiments, such as being cost effective, easy to try out different design alternatives, and having greater impact on product design. However, due to the complexity of FEA codes, it could be computationally expensive to calculate the quality response function over a large number of combinations of design and environmental factors. Traditional experimental design and response surface methodology, which were developed for physical experiments with the presence of random errors, are not very effective in dealing with deterministic FEA simulation outputs. In this thesis, we will utilize a spatial statistical method (i.e., Kriging model) for analyzing deterministic computer simulation-based experiments. Subsequently, we will devise a sequential strategy, which allows us to explore the whole response surface in an efficient way. The overall number of computer experiments will be remarkably reduced compared with the traditional response surface methodology. The proposed methodology is illustrated using an electronic packaging example.

No description available.

In this work, an active flow control method is studied numerically by using a synthetic jet over a NACA 0015 airfoil. Unsteady, turbulent flows over the NACA 0015 airfoil are computed using a Navier-Stokes solver. The Spalart-Allmaras turbulence model is employed in all computations. Unsteady flow solutions are computed in parallel using Parallel Virtual Machine library routines in a computer cluster. The synthetic jet is implemented to the flow solver as a boundary condition. Response Surface Methodology is employed for the optimization of synthetic jet parameters at various angles of attack. The synthetic jet parameters / the jet velocity, the jet location, the jet angle and the jet frequency are optimized to maximize the lift to drag ratio. The optimization study is performed for a constant value of jet power coefficient. The jet slot size is used as a dependent parameter in the optimization studies. The optimization study has shown that the jet velocity and the jet location are the dominant synthetic jet parameters. The optimum synthetic jet angle is observed to be increasing as the angle of attack increases. The optimum jet location is observed to be moving through the leading edge as angle of attack increases for the separated flows. It is observed that the application of the synthetic jet delays the flow separation on the suction side of the airfoil and increases the lift to drag ratio significantly especially at post stall angles of attack. The application of the synthetic jet is observed to be less effective for attached flows.

Active flow control by a jet over a 12.5% thick elliptic profile is investigated numerically. Unsteady flowfields are calculated with a Navier Stokes solver. The numerical method is first validated without the jet and with the presence of steady-blowing and pulsating jets. Three jet types, namely steady, pulsating and synthetic jets, are next compared with each other and it is shown that the most drag reduction is achieved by a synthetic jet and the most lift enhancement is achieved by a steady jet. The influences of the jet location, the jet velocity, the jet frequency, the jet slot length and the jet angle on the flowfield is parametrically studied. It is shown that the jet location and the jet velocity are the most effective parameters. The jet parameters are optimized to minimize the drag coefficient while keeping the jet power constant. The drag is reduced by 32.5% for the angle of attack 0 and by 24% for the angle of attack 4.