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A degradação oxidativa dos lipídeos é um fator preponderante que limita a vida útil dos alimentos, reduzindo suas qualidades nutricionais e organolépticas. A utilização de antioxidantes durante o processo de fabricação pode diminuir consideravelmente a extensão da oxidação lipídica, desencadeada pela reação de radicais livres. A crescente preocupação pelo consumo de alimentos mais saudáveis e livres de aditivos sintéticos tem recebido maior atenção pelas indústrias, que atualmente tem procurado por alternativas mais naturais, como o uso de antioxidantes provenientes de especiarias, como uma forma promissora de substituição dos compostos sintéticos. O objetivo deste trabalho foi estudar as condições de obtenção de extratos hidroalcoólicos de cravo (Syzygium aromaticum), canela (Cinnamomum verum) e pimenta dedo-de-moça (Capsicum annuum) e sua aplicação em óleos de soja refinado, armazenado em embalagens de vidro, em comparação com amostras adicionadas de antioxidante sintético TBHQ e amostras livres de antioxidantes (controle), durante sete meses, simulando a comercialização em supermercados. Foram verificados também as propriedades antioxidantes dos extratos de especiarias produzidos nas condições selecionadas através das metodologias de DPPH e ABTS. O estudo do efeito da temperatura de extração e do grau de hidratação do etanol sobre o rendimento de compostos fenólicos totais dos extratos destas especiarias foi realizado com aplicação de planejamento experimental e metodologia de superfícies de resposta. As condições para uma extração eficiente dos compostos fenólicos do cravo, da canela e da pimenta foram o emprego de etanol a 49,5 % (v/v). As melhores temperaturas estiveram entre 45 a 50 °C para o cravo e canela, e 60 °C para a pimenta. Os extratos de cravo, canela e pimenta dedo-de-moça preparados nas condições otimizadas, foram adicionados nas proporções de 50 mg kg-1, 100 mg kg-1, 150 mg kg-1 e 200 mg kg-1 às amostras de óleo de soja refinado e submetido a um teste acelerado em estufa a 65 °C juntamente com amostras adicionadas nas mesmas proporções de TBHQ e amostras isentas de antioxidantes (controle), para verificação da concentração mais eficiente no retardar a oxidação. Em seguida, após os resultados do teste de estufa, os óleos adicionados de 100 mg kg-1 de extratos, TBHQ, e isento de antioxidantes foram acondicionados em embalagens de vidro transparente de 250 mL e armazenados sob condições de comercialização (incidência de luz fluorescente por 15 horas / 24 horas e 331,71 Lux). Os resultados de Índice de Peróxido, Acidez e Absortividade na faixa do ultravioleta evidenciaram que os extratos foram capazes de oferecer proteção antioxidante ao óleo de soja refinado em diferentes níveis, sendo que o tratamento adicionado de extrato de cravo foi o que mais se destacou na inibição da oxidação lipídica do óleo de soja, seguido do extrato adicionado de canela e pimenta (p<0,05). / Lipid deterioration is a major cause of shorter food shelf life, reducing its nutritional and organoleptical quality. The use of antioxidants during the manufacturing process can significantly decrease the extent of lipid oxidation reactions triggered by free radicals. The growing concern about the consumption of healthier foods and free from synthetic additives has received increased attention by the industry, which is currently looking for more natural alternatives, such as the use of antioxidants from herbs and spices, as a promising replacement of synthetic compounds. The objective of this work was to study the conditions for obtaining hydroalcoholic extracts of cloves (Syzygium aromaticum), cinnamon (Cinnamomum verum) and red pepper (Capsicum annuum) and its application in soybean oil refined, stored in glass containers, compared with samples added of synthetic antioxidant TBHQ and samples free antioxidant (control) during 7 months simulating marketing conditions in supermarkets. Extracts were analyzed by DPPH and ABTS methods. The study of the effect of extraction temperature and the degree of hydration of ethanol on the yield of total phenolic compounds of the extracts of these spices was carried out with application of experimental design and response surface methodology. The best solvent concentration for efficient extraction of phenolic compounds from clove, cinnamon and pepper was 49.5% ethanol (v / v). The best temperatures were between 45 and 50°C for cloves and cinnamon, and 60 ° C for pepper. The extracts of clove, cinnamon and red pepper prepared under optimized conditions were added in concentration of 50 mg kg-1 , 100 mg kg-1, 150 mg kg-1 and 200 mg kg-1 to samples of refined soybean oil and subjected to an accelerated storage test at 65°C with samples containing the same concentrations of TBHQ and samples free of antioxidant (control) in order to check the most efficient concentrations to slow the oxidation. The best extracts concentration 100 mg kg-1 from the Schaal oven test was added to oil packed in glass containers against oil with 100 mg kg-1 of TBHQ, and oils free of antioxidants and stored under normal commercialization conditions (fluorescence light exposure for 15 hours / 24 hours and 333,71 Lux). Peroxide, acid values and absorptivity in the ultraviolet range showed that the extracts were able to offer antioxidant protection to soybean oil at different levels. Clove extract, showed the best performance in the inhibition soybean oil oxidation, followed by cinnamon and pepper (p<0,05).

<p>Cilj ovog rada je ispitivanje mogućnosti primene koncepta neuronskih mreža i postupka odzivne povr&scaron;ine za modelovanje cross-flow mikrofiltracije suspenzija kvasca. Drugi cilj je bio ispitivanje pobolj&scaron;anja procesa primenom Kenics statičkog me&scaron;ača kao promotora turbulencije. Primena statičkog me&scaron;ača ispitana je i sa energetskog stanovi&scaron;ta, a ne samo sa aspekta povećanja fluksa permeata. Svi eksperimenti izvedeni su u uslovima recirkulacije i koncentrisanja napojne suspenzije.</p><p>Dobijeni rezultati ukazuju da se pobolj&scaron;anje mikrofiltracije može se ostvariti primenom statičkog me&scaron;ača bez primene dodatne opreme. Tokom eksperimentalnog rada porast fluksa iznosio je između 89,32% i 258,86% u uslovima recirkulacije napojne suspenzije u zavisnosti od odabranih eksperimentalnih uslova, dok je u uslovima koncentrisanja napojne suspenzije porast fluksa imao vrednosti od 100% do 540% u istom eksperimentalnom opsegu.</p><p>Koncept neuronskih mreža daje veoma dobre rezultate fitovanja posmatranih odziva.<br />Pored primene ovog koncepta ispitana je i mogućnost procene uticaja pojedinih<br />eksperimentalnih promenljivih na odzive primenom jednačine Garsona i metode jačine sinapsi koje povezuju neurone. Rezulati ovog ispitivanja u saglasnosti su sa regresionom analizom.</p><p>Za detaljniju analizu uticaja eksperimentalnih promenljivih na posmatrane odzive primenjen je postupak odzivne povr&scaron;ine funkcije. Prvi korak u ovom segmentu istraživanja bio je određivanje uticaja srednjeg prečnika pora membrane na proces mikrofiltracije. Najbolji rezultati dobijeni su za membranu srednjeg prečnika 200 nm, po&scaron;to kod većih prečnika pora dolazi do izraženijeg unutra&scaron;njeg prljanja koje rezultuje manjim vrednostima fluksa permeata tokom proces mikroflitracije.</p><p>Dalja istraživanja usmerena su na ispitivanje uticaja pojedinih eksperimentalnih promenljivih ali i njihovih interakcija za odabranu membranu (srednji prečnik pora 200 nm). Rezultati fitovanja eksperimentalnih podataka dobijeni za jednu membranu bolji su u poređenju sa rezultatima kada su fitovani eksperimentalni rezultati za sve tri kori&scaron;tene membrane. Sa energetske tačke gledi&scaron;ta primećeno je da je najbolje raditi u umerenom opsegu protoka napojne suspenzije. Kao kranji cilj primene postupka odzivne povr&scaron;ine urađena je optimizacija vrednosti eksperimentalnih promenljivih, primenom postupka željene funkcije. Optimalni uslovi rada dobijeni u uslovima recirkulacije napojene suspenzije su transmembranski pritisak 0,2 bara, koncentracija napojne suspenzije 7,54 g/l i protok 108,52 l/h za maksimalne vrednosti specifične redukcije potro&scaron;nje energije. Sa sruge strane u uslovima koncentrisanja napojne suspenzije eksperimentalne promenljive imale su vrednosti transmembranski pritisak 1 bar, koncentracija napojne suspenzije 7,50 g/l i protok 176 l/h za maksimalne vrednosti specifične redukcije potro&scaron;nje energije.</p> / <p>The aim of this work was to investigate<br />possibilities of applying neural network and<br />response surface methodology for modeling crossflow<br />microfiltration of yeast suspensions. Another<br />aim was to investigate the improvement of process<br />using Kenics static mixer as turbulence promoter.<br />Experimental work was performed on 200, 450 and<br />800 nm tubular ceramic membranes. The use of<br />static mixer was also examined from an energetic<br />point of view not only its influence on permeate<br />flux. All experiments were done in recirculation and<br />concentration mode.<br />The results clearly show that the<br />improvement of cross-flow microfiltration of yeast<br />suspensions performances can be done with static<br />mixer without any additional equipment. In<br />experimental work, flux increase had values<br />between 89.32% and 258.86% for recirculation of<br />feed suspension depending on experimental values<br />of selected variables while in concentration mode<br />this improvement was in range between 100% and<br />540% for the same range of experimental variables.<br />Neural networks had excellent predictive<br />capabilities for this kind of process. Besides<br />examination of predictive capabilities of neural<br />networks influence of each variable was examined<br />by applying Garson equation and connection<br />weights method. Results of this analysis were in<br />fairly good agreement with regression analysis.<br />For more detailed analysis of variables influence on<br />the selected responses response surface<br />methodology was implemented. First step was to<br />investigate the influence of membrane pore size on<br />the process of microfiltration. The results suggested<br />that the best way to conduct microfiltration of yeast<br />suspensions is by using the membrane with mean<br />pore size of 200 nm, because bigger mean pore size<br />can lead to more prominent internal fouling that<br />causes smaller flux values.<br />Further investigations of microfiltration<br />process were done in order to investigate influences<br />of variables as well as their interactions and it was<br />done for the membrane with pore size of 200 nm.<br />Results for this membrane considering regression<br />analysis were considerably better compared with<br />results obtained for modeling all three membranes.<br />From the energetic point of view it was concluded<br />that it is optimal to use moderate feed flows to<br />achieve best results with implementation of static<br />mixer.<br />As the final goal of response surface<br />methodology optimization of process variables was<br />done by applying desirability function approach.<br />Optimal values of process variables for<br />recirculation of feed suspension were<br />trasmembrane pressure 0.2 bar, concentration 7.54<br />g/l and feed flow 108.52 l/h for maximal values of<br />specific energy reduction. On the other side for<br />concentration of feed suspension these variables<br />had values of 1 bar, 7.50 g/l and 176 l/h</p>

Joint probability methods for assessing storm surge flood risk involve the use of a collection of hydrodynamic storm simulations to fit a response surface model describing the functional relationship between storm surge and storm parameters like central pressure deficit and the radius of maximum wind speed. However, in areas with a sufficiently low probability of flooding, few storms in the simulated storm suite may produce surge, with most storms leaving the location dry with zero flooding. Analysts could treat these zero-depth, “non-wetting” storms as either truncated or censored data. If non-wetting storms are excluded from the training set used to fit the storm surge response surface, the resulting suite of wetting storms may have too few observations to produce a good fit; in the worst case, the model may no longer be identifiable. If non-wetting storms are censored using a constant value, this could skew the response surface fit. The problem is that non-wetting storms are indistinguishable, but some storms may have been closer to wetting than others for a given location. To address these issues, this thesis proposes the concept of a negative surge, or “pseudo-surge”, value with the intent to describe how close a storm came to causing surge at a location. Optimal pseudo-surge values are determined by their ability to improve the predictive performance of the response surface via minimization of a modified least squares error function. We compare flood depth exceedance estimates generated with and without pseudo-surge to determine the value of perfect information. Though not uniformly reducing flood depth exceedance estimate bias, pseudo-surge values do make improvements for some regions where <40% of simulated storms produced wetting. Furthermore, pseudo-surge values show potential to replace a post-processing heuristic implemented in the state-of-the-art response surface methodology that corrects flood depth exceedance estimates for locations where very few storms cause wetting.

Finite element simulation of thermoplastic components is gaining importance as the companies aim to avoid overdesign of the components. Cost of the component can be minimized by using an adequate amount of material for its application. Life of the component, in a particular application, can be predicted as early as during its design phase with the help of computer simulations. To achieve reliable simulation results, an accurate material model which can predict the material behaviour is vital. Most material models consist of a number of material parameters that needs to be fed into them. These material parameters can be identified with the inputs from physical tests. The accuracy of the data extracted from the physical tests, however, remains the base for the aforementioned process. The report deals with the implementation of optical measurement technique such as Digital Image Correlation (DIC) in contrast with the conventional extensometers. A tensile test is conducted on a glass fibre reinforced thermoplastic specimen, according to ISO 527-2/1A, to extract the experimental data with the help of DIC technique. The material behavior is reproduced within a finite element analysis software package LS-DYNA, with the combination of elastoplastic model called *MAT_024 and stress state dependent damage and failure model called GISSMO. The tensile test is performed under quasi-static condition to rule out the strain rate dependency of the thermoplastic material. The mesh sensitivity of the damage model is taken into account with the element size regularization. The thesis concerns setting up a routine for material parameter identification of thermoplastics by full-field calibration (FFC) approach. Also, comparison of the strain field in the specimen, obtained through the newly set up routine against the regular non-FFC i.e. extensometer measurement routine. The major objective being, through the comparisons, a qualitative assessment of the two routines in terms of calibration time vs. gain in simulation accuracy. Material models obtained through both the routines are implemented in three-point and four-point bending simulations. The predicted material behaviors are evaluated against experimental tests.

Biocatalytic membrane reactors combine the highly efficient biotransformation capability of enzymes with the selective filtration performance of membrane filters. Common strategies to immobilize enzymes on polymeric membranes are based on chemical coupling reactions. Still, they are associated with drawbacks such as long reaction times, high costs, and the use of potentially toxic or hazardous reagents. In this study, a reagent-free immobilization method based on electron beam irradiation was investigated, which allows much faster, cleaner, and cheaper fabrication of enzyme membrane reactors. Two industrial lipase enzymes were coupled onto a polyvinylidene fluoride (PVDF) flat sheet membrane to create self-cleaning surfaces. The response surface methodology (RSM) in the design-of-experiments approach was applied to investigate the effects of three numerical factors on enzyme activity, yielding a maximum activity of 823 118 U m2 (enzyme concentration: 8.4 g L1, impregnation time: 5 min, irradiation dose: 80 kGy). The lipolytic membranes were used in fouling tests with olive oil (1 g L1 in 2 mM sodium dodecyl sulfate), resulting in 100% regeneration of filtration performance after 3 h of self-cleaning in an aqueous buffer (pH 8, 37 C). Reusability with three consecutive cycles demonstrates regeneration of 95%. Comprehensive membrane characterization was performed by determining enzyme kinetic parameters, permeance monitoring, X-ray photoelectron spectroscopy, FTIR spectroscopy, scanning electron microscopy, and zeta potential, as well as water contact angle measurements.

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Catalytic pyrolysis technology is one of the thermochemical platforms used to produce high quality bio-oil and chemicals from biomass feedstocks. In the catalytic pyrolysis process, the biomass is rapidly heated under inert atmosphere in the presence of an acid catalyst or zeolite to promote deoxygenation and cracking of the primary vapors into hydrocarbons and small oxygenates. This dissertation examines the utilization of conventional fluid catalytic cracking (FCC) catalyst in the fractional catalytic pyrolysis of hybrid poplar wood. The influence of Y-zeolite content, steam treatment, addition of ZSM-5 additive, process conditions (temperature, weight hourly space velocity (WHSV) and vapor residence time) and recycling of the non-condensable gases (NCG) on the product distribution and the quality of the bio-oil were investigated. The first part of the study demonstrates the influence of catalytic property of FCC catalyst on the product distribution and quality of the bio-oil. It was found that FCC catalyst with higher Y-zeolite content produces higher coke yield and lower organic liquid fraction (OLF). Conversely, FCC catalyst with lower Y-zeolite content results in lower coke yield and higher OLF. The results showed that higher Y-zeolite content extensively cracks dehydrated products from cellulose decomposition and demethoxylates phenolic compounds from lignin degradation. The Y-zeolite promoted both deoxygenation and coke forming reactions due to its high catalytic activity and large pore size. Higher Y-zeolite content increased the quality of the bio-oil with respect to higher heating value (HHV), pH, density, and viscosity. The steam treatment at 732 oC and 788 oC decreased the total BET surface area of the FCC catalyst. The findings suggest that steam treatment reduces the coking tendency of the FCC catalyst and enhances the yield of the OLF. Analysis of the bio-oils showed that the steamed FCC catalyst produces bio-oil with lower viscosity and density. Gas chromatography and 13C-NMR spectrometry suggest that steam treatment affect the catalyst selectivity in the formation of CO, CO2, H2, CH4, C2-C5 hydrocarbons and aromatic hydrocarbons. The addition of ZSM-5 additive to the FCC catalyst was found to alter the characteristic/functionality of the catalytic medium. The product slate showed decrease in coke yield and increase in OLF with increase in ZSM-5 additive. The FCC/ZSM-5 additive hybrid catalysts produced bio-oils with relatively lower viscosity and higher pH value. The formation of CO2, CH4, and H2 decreased whilst C5 and aromatic hydrocarbons increased with increase in ZSM-5 additive level. The second part of the work assesses the effect of operating conditions on the catalytic pyrolysis process. The response surface methodology study showed reaction temperature to be the most influential statistically significant independent variable on char/coke yield, concentration of non-condensable gases, carbon content, oxygen content, pH and viscosity of the bio-oils. The WHSV was the most important statistically significant independent variable that affects the yield of organic liquid and water. Adequate and statistically significant models were generated for the prediction of the responses with the exception of viscosity. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The experiments with the model fluidizing gases showed that CO/N2, CO2/N2, CO/CO2/N2 and H2/N2 increase the liquid yield and CO2/N2 decrease char/coke yield. The results showed that recycling of NCG increases the higher heating value and the pH of the bio-oil as well as decreases the viscosity and density. The concept of recycling the NCG in the catalytic cracking of biomass vapors with FCC catalyst improved the overall process. The evaluation of the reactivity of conventional FCC catalyst towards bio-based molecules provide essential direction for FCC catalyst formulation and design for the production of high quality bio-oils from catalytic pyrolysis of biomass. / Ph. D.

This dissertation presents an empirical approach to identifying decisions for adapting cognitive radio parameters with no a priori knowledge of the environment. Cognitively inspired radios, attempt to combine observed metrics of system performance with artificial intelligence decision-making algorithms. Current architectures trend towards hybrid combinations of heuristics, such as genetic algorithms (GA) and experiential methods, such as case-based reasoning (CBR). A weakness in the GA is its reliance on limited mathematical models for estimating bit error rate, packet error rate, throughput, and signal-to-noise ratio. The CBR approach is similarly limited by its dependency on past experiences. Both methods have potential to suffer in environments not previously encountered. In contrast, the statistical methods identify performance estimation models based on exercising defined experimental designs. This represents an experiential decision-making process formed in the present rather than the past. There are three core contributions from this empirical framework: 1) it enables a new approach to decision making based on empirical estimation models of system performance, 2) it provides a systematic method for initializing cognitive engine configuration parameters, and 3) it facilitates deeper understanding of system behavior by quantifying parameter significance, and interaction effects. Ultimately, this understanding enables simplification of system models by identifying insignificant parameters. This dissertation defines an abstract framework that enables application of statistical approaches to cognitive radio systems regardless of its platform or application space. Specifically, it assesses factorial design of experiments and response surface methodology (RSM) to an over-the-air wireless radio link. Results are compared to a benchmark GA cognitive engine. The framework is then used for identifying software-defined radio initialization settings. Taguchi designs, a related statistical method, are implemented to identify initialization settings of a GA. / Ph. D.