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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Calibration of traffic models in SIDRA

Ekman, Anna-Karin January 2013 (has links)
This thesis studies calibration of SIDRA Intersection roundabout models. The calibration has been performed with three different methods; manual calibration of gap-acceptance parameters, manual calibration of the parameter environment factor and automatic calibration of the environment factor based on optimization. The main aim has been to evaluate and compare 3 the three methods. One part of the purpose was also to test the possibility of finding a general value of environment factor by testing a few different types of models. SIDRA Intersection is a micro-analytical model used for capacity and performance estimations. The capacity model is based on gap-acceptance theory where follow-up headway and critical gap have a great impact. An application for automatic calibration was developed in Microsoft Excel/VBA. The calibration process is based Differential evolution and the cost function uses root mean square percent error where capacity and average delay are used as performance measures. The application has been tested with a test model at first to make sure the calibration is correct. The application has then been tested on data from a site in Farsta, Stockholm. For this site all three calibration methods, the two manual and the automatic, has been tested. The results show that all three methods performed equally well, with only small differences in precision. The most effective method considering results and time required for process was the manual calibration of environment factor.In the last part of this project the method for manual calibration of environment factor was tested with three more models with different characteristics in order to investigate the possibility of finding one value for environment factor suitable for all approaches. However the tests show difference in environment factor between small and large roundabouts and difficulties to set one value for environment factor for two-lane approaches.
2

Entry-lane capacity analysis of roundabouts in Texas using VISSIM, SIDRA, and the highway capacity manual

Mills, Alison Fayre 29 September 2011 (has links)
Road safety and traffic congestion are two of the critical issues facing the transportation profession today. As a means to promote safety and efficiency at United States intersections modern roundabouts are becoming more and more common. Over the last ten years, roundabouts implementation methodologies have been developed using data collected at U.S. roundabouts. These methodologies were first published in National Cooperative Highway Report 572: Roundabouts in the United States and more recently in the second edition of the national roundabout guidelines. This work attempts to validate the use of these methodologies for roundabouts in the state of Texas and also enhance guidelines for evaluating roundabout operations by exploring the effects of exiting flow, origin-destination patterns, and mean speed on roundabout entry-lane capacity. Capacity results from VISSIM are compared to the Highway Capacity Manual entry-lane capacity curve and results from SIDRA. / text
3

PERFIL AROMÁTICO DE SUCOS E FERMENTADOS DE MAÇÃ EM DIFERENTES ESTÁDIOS DE MATURAÇÃO

Braga, Cíntia Maia 14 February 2013 (has links)
Made available in DSpace on 2017-07-21T18:53:20Z (GMT). No. of bitstreams: 1 Cintia Maia Braga.pdf: 853677 bytes, checksum: 4107ff87848d02112262f112adeb1c1b (MD5) Previous issue date: 2013-02-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apple fermented beverages are produced in Brazil with low commercial quality fruits that do not pass by rating the degree of maturation. An study becomes necessary to determine the aromatic profile of the products processed apples in different stages of maturation knowing that this can change the technological and sensory quality of the product. Thus the aim of this study was to identify and determine the differences between apple juices and apple fermented beverage elaborated with fruits from different varieties and ripening stages in the aroma profile. Analysis of fruit ripeness, preparation of products under different conditions, flavor profile, physico-chemical composition and statistical analysis for verification and determination of the differences between the juice and fermented were perfomed. The physical chemical characteristics attested the raw material ripening of the samples. The sugar content of juices and alcohol content of fermented in general increased with ripening increasing, the opposite of the evolution of acids that in most of the samples decreased with increasing ripening, as happened with the nitrogen content. Ripening stage significantly influenced the aroma composition of apple juice and apple fermented beverages. Esters, aldehydes, acids, alcohols and ketones were identified in all samples by gas chromatographic (GC), however at higher concentrations in samples of fermented mainly made of senescent apples. Regarding the juices, ripe Gala had a prominence relating to aroma concentration over other cultivars. Using a chemometric approach by principal components analysis (PCA) and hierarchical cluster analysis (HCA) were verified that fermented have a higher composition of ten volatile compounds avaliated and fewer concentration of just one compound than apple juices. In this way chemometric approach with GC techniques can be suitable parameters to differentiate apple juice and apple fermented by aroma profiles. / Fermentados de maçãs são produzidos no Brasil com frutas de baixa qualidade comercial que não passam por classificação quanto ao grau de maturação. Sabe-se que isto pode alterar a qualidade tecnológica e sensorial do produto tornando necessário um estudo para determinação do perfil aromático dos produtos processados com maçãs em diferentes estádios de maturação. O objetivo deste estudo foi identificar e determinar as diferenças de perfil aromático entre sucos e fermentados de maçã elaborados com frutas de diferentes cultivares e estádios de maturação. Para isto foram realizadas análises para determinação do estádio de maturação da fruta, determinação do perfil aromático, composição físico-química e análise estatística para verificação e determinação das diferenças entre os sucos e fermentados. O teor de açúcar dos sucos e de álcool dos fermentados em geral aumentaram com o amadurecimento, o oposto da evolução dos ácidos que, na maioria das amostras decresceu com o amadurecimento, tal como aconteceu com o teor de nitrogênio. O estádio de maturação influenciou significativamente a composição aromática de suco e fermentado de maçã. Ésteres, aldeídos, ácidos, álcoois e cetonas foram identificados em todas as amostras por cromatografia gasosa (GC), porém em concentrações mais elevadas em amostras de fermentado, principalmente a partir de maçãs senescentes. Em relação aos sucos, Gala madura teve um destaque com relação à concentração de aromas sobre outras cultivares. Através de uma abordagem quimiométrica por análise de componentes principais (PCA) e análise de agrupamento hierárquico (HCA) foi verificado que os fermentados tem uma maior concentração de dez dos compostos voláteis avaliados e menos concentração de apenas um composto em relação ao suco de maçã. Desta forma abordagem quimiométrica com técnicas de GC podem ser parâmetros adequados para diferenciar suco e fermentado de maçã por perfil aromático.
4

Influência da adição do bagaço imobilizado na evolução dos compostos fenólicos durante o processo fermentativo de mosto de maçã

Bortolini, Débora Gonçalves 02 March 2018 (has links)
Submitted by Eunice Novais (enovais@uepg.br) on 2018-05-08T14:02:58Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Débora Gonçalves Bortolini.pdf: 1564504 bytes, checksum: 39657eb7b03d2fdb74b9f8e842300341 (MD5) / Made available in DSpace on 2018-05-08T14:02:58Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Débora Gonçalves Bortolini.pdf: 1564504 bytes, checksum: 39657eb7b03d2fdb74b9f8e842300341 (MD5) Previous issue date: 2018-03-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A maçã, uma das frutas mais produzidas no mundo, tem sido consumida de diferentes formas, como em frutas in natura, sucos, produtos fermentados como sidras, bebidas destiladas, vinagres, além de geleias e frutas desidratadas. O aumento da escala de produção de sucos e sidras leva ao incremento da geração do bagaço. Este resíduo caracteriza como sendo uma fração rica em fibras, açúcares e compostos fenólicos com atividade antioxidante que não são totalmente extraídos durante o processamento. Portanto, o bagaço apresenta potencial para ser utilizado no melhoramento da qualidade de alimentos e bebidas. O objetivo deste trabalho foi estudar a extração de compostos fenólicos do bagaço de maçã imobilizado durante a fermentação de sidras, bem como, a evolução destes compostos no decorrer da fermentação e seu impacto na qualidade sensorial. Foram utilizadas maçãs da cultivar Fuji para produzir 20 sidras, as quais foram divididas em dois grupos: sidra I, controle ou sem adição de bagaço imobilizado, e sidra II, com adição de bagaço imobilizado. A fermentação das sidras foi interrompida, em duplicata, nos dias 1, 4, 7, 11 e 15 de fermentação, obtendo duas frações: as sidras e os bagaços fermentados, os quais foram submetidos a extrações consecutivas em metanol e acetona para análise da composição fenólica. Foram realizadas análises de nitrogênio total, cor, pH, acidez total, composição fenólica total, atividade antioxidante, além de composição fenólica individual, composição de açúcares, etanol e sorbitol por CLAE. Também foi realizada análise sensorial com 8 julgadores conhecedores do produto, onde foram avaliados os atributos de acidez, amargor, adstringência, cor e qualidade do odor por meio de escalas estruturadas. Foi observado uma redução do pH e aumento da acidez das sidras no decorrer da fermentação. Durante a fermentação foi observado um decréscimo de 40% dos compostos fenólicos totais da sidra I, o que pode estar relacionado à adsorção dos compostos na parede celular de leveduras e a bioconversão de compostos. No entanto, a sidra II apresentou 93 mg/L a mais de compostos fenólicos totais do que a sidra I, devido a extração desses compostos do bagaço, e por conseqüência, maior atividade antioxidante. Flavonoides, especialmente os flavonóis (quercetina-3-rutinosídeo, quercetina-3-Dgalactosídeo, quercetina-3-β-D-glucosídeo, quercetina-3-D-xilosídeo, quercetina-O-α-Larabinofuranosideo e quercetina-3-O-raminosídeo) foram a principal classe de compostos extraída. Além disso, ocorreu uma extração de açúcares, no início da fermentação da sidra II, o que impactou no seu teor alcoólico que foi mais alto do que na sidra I. Foi observado um residual de frutose nas sidras, o qual foi 0,3 g/L superior na sidra II. A cor de ambas as sidras foi amarela (h° próximo 90°), porém, a sidra II apresentou maior luminosidade. Segundo os resultados da análise sensorial, a sidra II foi mais amarga e menos ácida e a cor foi mais clara. A adstringência das duas bebidas não apresentou diferença significativa (p > 0,05). A qualidade do odor foi avaliada por método afetivo, sendo que ambas as sidras receberam notas entre “gostei ligeiramente” e “gostei moderadamente”. Nos bagaços residuais, após a fermentação, como esperado houve uma redução da quantidade de fenóis e da atividade antioxidante. Também foi observado um aumento na quantidade de nitrogênio no resíduo, devido à retenção de leveduras e também pela extração de compostos como açúcares, o que pode concentrar outros constituintes. Portanto, a utilização do bagaço imobilizado na fermentação pode melhorar a qualidade sensorial de sidras, diminuindo a percepção da acidez, aumentando o amargor e melhorando a cor da bebida, sem alterar a percepção da adstringência, além de aumentar a sua composição fenólica e atividade antioxidante. / The apple, one of the fruit more produced in the world, has been consumed in different ways, such as in raw fruits, juices, fermented products such as cider, distilled beverages, vinegar, as well as jams and dried fruits. The increase of the production scale of juices and ciders leads to increase of apple pomace production. This by-product characterizes as a fraction rich in fibers, sugars and phenolic compounds with antioxidant activity which are not totally extracted in the process. Therefore, the apple pomace shows potential to be used to improve the quality of foods and beverages. The aim of this work was to study the extraction of phenolic compounds from apple pomace immobilized during the fermentation of ciders. As well as, the evolution of this compounds during the fermentation and their impact on sensorial quality. It was used apples from Fuji variety to make 20 ciders, which were divided in 2 groups: cider I, control or without apple pomace addition, and cider II, with addition of apple pomace immobilized. The ciders fermentation were stopped, in supplicate, in the 1st, 4th, 7th, 11th and 15th days of fermentation, obtaining 2 fractions: the ciders and the fermented apple pomace, which were submitted to two consecutive extractions of methanol and acetone to phenolic composition analysis. It were carried out analysis od total nitrogen, color, pH, total titratable acidity, total phenolic composition, antioxidant activity, as well as individual phenolic composition, sugars, ethanol and sorbitol by HPLC. It was also carried out sensory analysis with 8 judges that knew the product, where it was evaluated the attributes of sourness, bitterness, astringency, color and odour quality by structured scales. It was observed a decrease of pH and an increase of titratable acidity of the ciders during fermentation. During the fermentation it was observed a reduction of 40% of total phenolic compounds of cider I, which can be relationed with the adsorption of compounds on cell wall of yeasts and the bioconversion of compounds. However, the cider II showed 93mg/L more total phenolic compounds than cider I, due the extraction of this compounds from apple pomace, and consequently, higher antioxidant activity. Flavonoids, especially flavonols (quercetin-3- rutinoside, quercetin-3-D-galactoside, quercetin-3-β-D-glucoside, quercetin-3-D-xyloside, quercetin-O-α-L-arabinofuranoside e quercetin-3-O-rhaminoside) was the main class of compounds extracted. Furthermore, occurred a extraction of sugars, in the beginning of fermentation of cider II, which impacted on their alcoholic degree which was higher on than cider I. It was observed a residual of fructose on ciders which was 0.3 g/L higher on cider II. The color of both ciders were yellow (h° near 90°), however, cider II showed higher lightness. Second the sensorial analysis results, the cider II ware more bitter and less sour, and their color was more light. The astringency for both beverages did not show significative difference (p > 0.05). the odour quality was evaluated by affective method, being the both ciders received notes between “ I liked quickly” and “I liked moderately”. In the residual apple pomaces, after fermentation, as expected had a reduction of the quantity of phenols an antioxidant activity. It was also observed an increase of total nitrogen, due the yeasts cell retention and also by extraction of sugars, which can concentrate other constituents. Therefore, the use of immobilized apple pomace on fermentation can improve the sensorial quality of ciders, reducing the perception of sourness, increasing the bitterness e improving the color of the beverage, without modify the perception of astringency, futhermor uncrease their phenolic composition and antioxidant activity.

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