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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.
471

Infiltration in teilweise gefrorene Böden: Experimente und Modellrechnungen

Fritz, Heiko 01 September 2004 (has links)
In der vorliegenden Arbeit wurden Doppelringinfiltrationsexperimente an teilweise gefro­renen Böden durchgeführt. Diese Experimente wurden anschließend mit den zwei computer­ge­stützten Modellen, Erosion 3D / Winter und COUP, nachgestellt, um die Frage zu beantworten, ob es möglich ist, die Infiltration in teilweise gefrorene Böden vorherzusagen. Die Doppelringinfiltrationsexperimente wurden auf einem ackerbaulich genutzten Lehm­boden mit geringer Lagerungsdichte und Bodenfeuchten im Bereich der Feld­kapa­zität, an der nördlichen Grenze des hydrologischen Untersuchungsgebietes „Schäfertal“ durch­ge­führt. Drei Experimente erfolgten bei teilweise gefrorenen und ein Experiment bei unge­frorenem Boden. Bei diesen Experimenten wurde herausgefunden, dass die Endinfiltrationsrate des gefro­renen Bodens mit 7·10-5 m/s gleich der Endinfiltrationsrate des ungefrorenen Bodens war. Während bei dem Infiltrationsexperiment mit ungefrorenem Boden die Endinfiltrations­rate bereits nach 10 bis 20 min erreicht war, wurden bei den Experimenten mit gefrorenen Böden aufgrund der zusätzlichen Sättigung des kryoturbativen Sekundärporenvolumens mehr Zeit benötigt. Zu den im Boden ablaufenden Prozessen bei Zugabe von Infiltrationswasser (Tem­pe­ratur­veränderung, Gefrier- und Auftauprozesse, Veränderung der Porosität) besteht noch Klärungsbedarf. Der für die Modellierung wichtige Eingabeparameter der Anfangsbodenfeuchte konnte bei winterlichen Bedingungen nicht genau bestimmt werden. Gravimetrische Boden­feuchtebestimmungen liefern aufgrund des Eintrags von zusätzlichen Eis- und Schnee-Wasser zu hohe Werte. TDR- und Watermark-Messungen unterschätzen hingegen die Bodenfeuchten, weil sie nur den Anteil des flüssigen Wassers berücksichtigen. Mit Erosion 3D / Winter konnten die Ergebnisse der Infiltrationsexperimente, unter der Voraussetzung, dass die effektive gesättigte hydraulische Leitfähigkeit des ungefrorenen Bodens exakt bekannt war, sehr gut nachgestellt werden. Eine Modellierung der Infiltration in einen teilweise gefrorenen Boden ist damit, zumindest für den untersuchten Boden und die betrachteten meteorologischen Bedingungen, möglich. Das COUP - Modell lieferte dagegen völlig andere Ergebnisse, weil von einem Ein­frieren des infiltrierten Wassers bei negativen Temperaturen ausgegangen wird. Eine Verbesserung der Infiltrationsbeschreibungen könnte hier wahrscheinlich durch die Vorgabe einer größeren Anzahl von Eingabeparametern, die die natürliche Situation besser repräsentieren als die für die Modellierung verwendeten Daten, erfolgen.
472

Análisis de los factores transporte, almacenaje y tecnologías dentro la cadena de frío que influyen en la cadena de valor de las empresas peruanas exportadoras de atunes de aleta amarilla congelados a Ecuador durante el periodo 2014-2018 / Analysis of the cold chain factors that influence the value chain of Peruvian companies that export frozen yellowfin tunas except livers and roe to Ecuador during the 2014-2018 period

Morales Salinas, Juan Daniel, Torres Robles, Celia Elizabeth 14 August 2020 (has links)
Actualmente, los países en vías de desarrollo (PED) vienen siendo blancos de interés de inversión para empresas multinacionales dedicadas al rubro alimentario, estos países cuentan con una amplia oferta de productos alimenticios. No obstante, en el caso de los productos congelados, estos países no suelen ser competitivos, al no contar con la adecuada implementación y gestión de la cadena de frío se obtienen grandes cantidades de desperdicios de comida y, por ende, pérdidas económicas. Perú es considerado un PED por lo cual, pese a tener una importante participación en la oferta de productos pesqueros de la región, no es indiferente a las consecuencias del mal manejo de la cadena de frío y el efecto sobre los márgenes de utilidad de los exportadores. Por ello, para estudiar esta problemática la presente tesis analizó los factores de la cadena de frío que influyeron en la cadena de valor de las empresas peruanas exportadoras de atunes de aleta amarilla congelados a Ecuador durante el periodo 2014-2018. Mediante la metodología con enfoque cualitativo, a través de entrevistas a especialistas del sector y empresas exportadoras de productos congelados. Se pudo determinar que el transporte, almacenaje, uso de tecnologías de información y la participación del estado son las principales variables de interés y relevancia. Asimismo, la trazabilidad sobre el control de temperatura ocasiona una buena gestión de calidad. Se demostró que se debe impulsar y fomentar la industria de frío por parte del gobierno peruano pues la oferta es escasa, por ende, los costos son elevados y hace que el sector no sea atractivo para posibles inversiones. Se recomienda tomar en cuenta para futuros estudios el papel del estado de los PED y su influencia en la implementación de la cadena de frío. / Currently, developing countries have been targets of investment interest for multinational companies dedicated to the food industry. These countries have a wide range of food products. However, in the case of frozen products, developing countries are not usually competitive, as they do not have the proper implementation and management of the cold chain. Large amounts of food waste are obtained and, therefore, economic losses. Peru is considered a developing country for which, despite having an important share in the supply of fishery products in the region, it is not indifferent to the consequences of poor management of the cold chain and the effect on exporters' profit margins. To study this problem, this thesis analyzed the cold chain factors that influenced the value chain of Peruvian companies exporting frozen yellowfin tuna except for livers, roe, and milk to Ecuador during the 2014-2018 period. Through the methodology with a qualitative approach, through interviews with specialists in the sector and companies that export frozen products. It was determined that transportation, storage, use of information technologies, and state participation are the main variables of interest and relevance. Also, traceability on temperature control leads to good quality management. It was shown that the cold industry should be promoted by the Peruvian government since the supply is scarce, therefore, the costs are high and makes the sector unattractive for possible investments. It is recommended to consider for future studies the role of the state of developing countries and their influence on the implementation of the cold chain. / Tesis
473

Water, Heat and Solute processes in Seasonally frozen Soils : Experimental and Modeling Study

Wu, Mousong January 2015 (has links)
Soil freezing and thawing is of importance in transport of water, heat and solute, which has coupled effects. Solute type and solute content in frozen soil could influence the osmotic potential of frozen soil and decrease freezing point, resulting in differences in soil freezing characteristic curves under various solute conditions. Prediction model provides an approach for estimating soil freezing characteristic curves under various water and solute conditions based on soil freezing characteristic curve obtained at certain water and solute conditions. Water, heat and solute transport in seasonally frozen soil is a coupled process strongly linked to evaporation and energy balance of soil surface. High solute content and shallow GWTD provide good conditions for water and solute accumulation in surface layer, which would result in more evaporation during thawing. Also, high solute content in upper layer would cause more liquid water to exist in upper layer, which may enhance evaporation during freezing period. Obvious increase in cumulative evaporation amount was detected for frost tube experiments, 51.0, 96.6, to 114.0 mm when initial solute content increased from 0.2%, 0.4%, to 0.6%, and initial GWTD of 1.5 m. Similar trends were observed for other GWTD and solute treatments. Water and heat transport simulated by the CoupModel combined with GLUE calibration showed good performances, when constrained by certain criteria. Uncertainties were investigated using ensemble of modeling results. Simulated energy partitioning showed intensive oscillations in daily courses during soil freezing/thawing periods and strongly influenced the stability of energy system on surface of soil. The study demonstrated the complexity in water, heat and solute transport in seasonally frozen soil, and the necessity of combining experimental data with numerical model for better understanding the processes as well in decision making for irrigation district water resources management. / 土壤冻融过程对于水热及溶质的运移具有十分重要的影响,并对于寒旱区水文过程的研究有着深远意义。在冻土中,溶质的种类及溶质含量会对土壤溶质势产生影响,并导致冰点的降低,进而影响土壤冻结曲线的变化。本研究通过建立含盐冻土冻结曲线的预报模型,有效地利用一定水盐试验条件下的冻结曲线对未知条件下的冻结曲线进行预测,进而为数值模型实时根据土壤水盐条件获得准确的液态含水量与温度的关系时提供了可行的方法。冻融土壤中的水热盐运移过程与地表的水热平衡有着密切联系,进而影响冻融土壤蒸发过程。试验研究表明,高溶质含量及浅埋深地下水条件为地表的蒸发提供了便利条件,因为高溶质含量土壤冰点降低,同一负温条件下的液态含水量增大,为蒸发提供了可利用水分;而浅埋深地下水对冻融期水盐的表聚提供的方便,进而有助于融化期地表水分的大量蒸发及下层土层水分的大量向上补给。例如,当地下水初始埋深设置在1.5 m时,对于初始含盐量分别为0.2%,0.4% 和0.6% g/g的冻融试验组,冻融期累积蒸发量分别为51.0,96.6和114.0 mm。同样的增加趋势在其它初始地下水埋深设置试验组里也被验证,且初始地下水埋深越浅,累积蒸发量也越大。CoupModel 与GLUE相结合的方法能够有效地根据实测数据对模型进行率定并经过筛选后得出较好的模拟结果集合。通过对筛选的模拟输出集合的不确定性分析,对模型模拟过程的不确定性有了很好的了解。模拟的地表能量分配过程显示,地表能量的日变化过程较为剧烈,并且对地表能量平衡系统的稳定性产生了显著影响。研究通过试验与模拟相结合的方法,展示了季节性冻融土壤中水热盐耦合运移过程的复杂性,同时也表明利用试验取样与数值模型相结合的方法研究冻融土壤中水热盐运移过程的必要性,并为高效的水资源管理决策的制定提供了有效的手段。 / <p>QC 20150518</p>
474

Obtenção e caracterização de Minced Fish de sardinha e sua estabilidade durante a estocagem sob congelamento / Obtaining and characterization of Minced Fish sardines and its stability during storage under freezing

Neiva, Cristiane Rodrigues Pinheiro 06 June 2003 (has links)
É muito elevado o potencial de utilização do pescado na forma de minced fish - MF, servindo de matéria-prima para outros produtos. O MF de sardinha foi avaliado quanto ao rendimento, ao efeito da lavagem sobre a melhoria da cor, à caracterização química e quanto à estabilidade química e sensorial durante estocagem sob congelamento de -17 a -18°C. O rendimento do MF de sardinha lavado com água foi de 55% em relação ao peixe inteiro e próximo do rendimento teórico da parte comestível. A lavagem do MF com água ou água + bicarbonato de sódio proporcionou a obtenção de um produto com cor vantajosamente mais clara e apreciável. Com relação à composição química básica o MF de sardinha lavado com água apresentou maior hidratação e menor teor de cinzas em relação ao controle e semelhantes quantidades de proteína e lípides. Comparado ao controle, o MF de sardinha lavado com água, não apresentou diferença quanto ao perfil de ácidos graxos e pH, o que não ocorreu com o nitrogênio das bases voláteis - N-BVT, que diminuiu, e às substâncias reativas ao ácido tiobarbitúrico - TBARS, que aumentaram. O MF de sardinha lavado com água, contendo ou não antioxidantes artificialmente adicionados, apresentou estabilidade química e sensorial quando mantido sob congelamento, com base nos parâmetros pH, N-BVT, TBARS, odor a ranço e cor, em até 26 semanas de estocagem. Os resultados do presente trabalho são favoráveis à possibilidade de obtenção de MF de sardinha lavado com água e seu emprego como matéria-prima para outros produtos pesqueiros. / The potentiality of fish\'s utilization as minced fish - MF is very high, actually turning into a raw material to other products. The sardine\'s MF was evaluated according to its yield, the washing effect improving the color, its chemical characteristic and chemical and sensorial stability, during frozen storage under -17,-18°C. The yield of sardine\'s MF washed in with water, was 55% related to the whole fish and close to the theoretic yield of eatable portion. The MF\'s washing in water or in water plus sodium bicarbonate provide a product with clearer and more desirable color. Related to the chemical basic composition, sardine\'s MF washed in water, presented better hydration and lower ashes contents than its control, and similar quantity of protein and lipids. Compared to the control, the sardine\'s MF washed in water, had not presented any difference related to the fatty acids profile and pH, that had not happened with the nitrogen of volatile bases - N-BVT, which had been decreased, and the thiobarbituric acid reactant substances - TBARS, that had been increased. The sardine\'s MF washed in water, containing or not added antioxidants, was chemical and sensorial stable when maintained frozen, based on parameters as pH, N-BVT, TBARS, rancidity odor, and color, stored for 26 weeks. The results of this work are propitious to the possibility of achieving sardine\'s MF washed in water, and your utilization as a raw material to others seafoods.
475

Corpo sitiado..., a comunicação invisível: dança, rodas e poéticas

Correia, Fátima Daltro de Castro 11 September 2007 (has links)
Made available in DSpace on 2016-04-26T18:16:22Z (GMT). No. of bitstreams: 1 Fatima Daltro de Castro Correia.pdf: 981156 bytes, checksum: c066fd1d35e52db7caca7f986cb0bf9e (MD5) Previous issue date: 2007-09-11 / The increase of the images media exposition of wheels chair bodies promotes the impression to collaborate for the social inclusion of the body that we nominate deficient. However, the action of the nominations consecrated for the press, as of pcd (person with deficiency), operates exactly in the contrary direction, exposing the deficiency, transforming it into a stigma. The images of wheels chair bodies that are spreadon media are always associates to the question of the overcoming of limits, tying those bodies only to the values in circulation in the sport world. The prominence that the Paraolimpics Games occupies in the media inserts there, in the consolidation of the boarding of these bodies with images that congeal around an uniform way of the deficiencies in an only niche, delimited for the adopted concept of efficiency/productivity. A critical reflection regarding this situation becomes necessary to be able to deal with the dance that this body practises outside the narrow limits imposed for this stigma mechanism. For this, we here adopt the Theory Corpomedia (Katz & Greiner), with which if it presents the hypothesis of that the wheels chair body dancer is a complex system and able to breach with the perverse speech that the frozen images produce. The concept of corpomedia, formulated from the study of the communication between body, and its environments, favor the agreement of the paper that the media exploration has when it congeals the images that produce around the deficiency and not of the deficient one with its singularities. The methodology contemplates a Study of Case, Judite wants to cry, but it does not get it! , created for the wheels chair dancer Edu Oliveira; interviews aiming qualitative research; critical analysis of these interviews, carried through after the presentation of the spectacle in two different cities (Salvador and Votorantim); bibliographical revision of the subject of the deficient body; video registers. The bibliographical research allowed a brief historical panoramic sketch of the access of the wheels chair bodies to the world of dance and its social implications. Conclusion is that that the wheels chair dancer is cultural and biologically implied in a system of construction of images that associates him with a poor body and that they feed who it cognitivaly, with ominous consequences for the process of its social inclusion. From there the urgency in promoting actions that can breach with the media action in course. This is the role for the dance in wheels chair has and, to accomplish it, cannot be remained based in the criteria of the sport. The dance in wheels chair needs to discover its poetical, therefore they are who potencializes an effective social insertion / O aumento da exposição midiática de imagens de corpos cadeirantes promove a impressão de colaborar para a inclusão social do corpo que nomeamos de deficiente. Todavia, a ação das nomeações consagradas pela imprensa, como a de pcd (pessoa com deficiência), opera justamente no sentido contrário, midiatizando a deficiência, transformando-a em um estigma. As imagens de corpos cadeirantes que ganham divulgação estão sempre associadas à questão da superação de limites, vinculando aqueles corpos somente aos valores em circulação no mundo do desporto. O destaque que a Paraolimpíada ocupa na mídia se insere aí, na consolidação da abordagem desses corpos com imagens que se congelam em torno de uma uniformização das deficiências em um nicho único, delimitado pelo conceito de eficiência/produtividade adotado. Faz-se necessária uma reflexão crítica a respeito dessa situação para poder tratar da dança que esse corpo pratica fora dos estreitos limites impostos por esse mecanismo estigmatizador. Para isso, aqui se adota a Teoria Corpomídia (Katz & Greiner), com a qual se apresenta a hipótese de que o corpo do dançarino cadeirante é um sistema complexo e apto a romper com o discurso perverso que as imagens congeladas produzem. O conceito de corpomídia, formulado a partir do estudo da comunicação entre corpo, e seus ambientes, favorece o entendimento do papel que a exploração midiática tem quando congela as imagens que produz em torno da deficiência e não do deficiente com suas singularidades. A metodologia contempla um Estudo de Caso, o do espetáculo Judite quer chorar, mas não consegue! , criado pelo dançarino cadeirante Edu Oliveira; entrevistas com fins de pesquisa qualitativa; análise crítica dessas entrevistas, realizadas após a apresentação do espetáculo em duas cidades diferentes (Salvador e Votorantim); revisão bibliográfica do tema do corpo deficiente; registros em vídeo. A pesquisa bibliográfica permitiu um breve esboço panorâmico/ histórico do acesso dos cadeirantes ao mundo da dança e suas implicações sociais. Concluiu-se que o dançarino cadeirante é cultural e biologicamente implicado em um sistema de construção de imagens que o associam ao corpo coitadinho e que são elas que o alimentam cognitivamente, com conseqüências nefastas para o processo de sua inclusão social. Daí a urgência em promover ações que possam romper com a ação midiática em curso. É esse o papel que a dança em cadeira de rodas tem e, para desempenhá-lo, não pode se manter pautada pelos critérios do desporto. A dança em cadeira de rodas precisa descobrir as suas poéticas, pois são elas que potencializam uma inserção social efetiva
476

Heat transfer process between polymer and cavity wall during injection molding / Wärmeübergang zwischen Polymerwerkstoff und Werkzeugwand beim Spritzgießprozess

Liu, Yao 22 January 2015 (has links) (PDF)
Injection molding is one of the most commonly applied processing methods for plastic components. Heat transfer coefficient (HTC), which describes the heat conducting ability of the interface between a polymer and cavity wall, significantly influences the temperature distribution of a polymer and mold during injection molding and thus affects the process and quality of plastic products. This thesis focuses on HTC under diverse processing situations. On the basis of the heat conducting principle, a theoretical model for calculating HTC was presented. Injection mold specially used for measuring and calculating HTC was designed and fabricated. Experimental injection studies under different processing conditions, especially different surface roughness, were performed for acquiring necessary temperature data. The heat quantity across the interface and HTC between a polymer and cavity wall was calculated on the basis of experimental results. The influence of surface roughness on HTC during injection molding was investigated for the first time. The factors influencing the HTC were analyzed on the basis of the factor weight during injection molding. Subsequently FEM (Finite element method) simulations were carried out with observed and preset value of HTC respectively and the relative crystallinity and part density were obtained. In the comparison between results from simulation and experiment, the result calculated with observed HTC shows better agreement with actually measured value, which can verify the reliability and precision of the injection molding simulation with observed HTC. The results of this thesis is beneficial for understanding the heat transfer process comprehensively, predicting temperature distribution, arranging cooling system, reducing cycle time and improving precision of numerical simulation. / Das Spritzgießen ist eines der am häufigsten angewandten Verarbeitungsverfahren zur Herstellung von Kunststoffkomponenten. Der Wärmedurchgangskoeffizient (WDK), welcher den Wärmeübergang zwischen Kunststoff und Werkzeugwand beschreibt, beeinflusst während des Spritzgießens maßgeblich die Temperaturverteilung im Bauteil und dem Werkzeug und folglich den Prozess und die Qualität der Kunststoffprodukte. Der Inhalt dieser Arbeit beschäftigt sich mit dem WDK unter verschiedenen Prozessbedingungen. Auf Grundlage des Wärmeleitungsprinzips wurde ein theoretisches Modell für die Berechnung des WDK vorgestellt. Es wurde dazu ein Spritzgießwerkzeug konstruiert und hergestellt, welches Messungen zur späteren Berechnung des WDK ermöglicht. Praktische Spritzgießversuche unter verschiedenen Prozessbedingungen, insbesondere unterschiedlicher Oberflächenrauheit, wurden für die Erfassung der erforderlichen Temperaturdaten durchgeführt. Auf Grundlage der experimentellen Ergebnisse wurde der Wärmeübergang zwischen dem Polymer und der Werkzeugwand berechnet. Der Einfluss der Oberflächenrauhigkeit auf den WDK wurde hierbei zum ersten Mal untersucht. Auf Grundlage des Bauteilgewichtes wurden anschließend die Faktoren, die den WDK beeinflussen, berechnet. Des Weiteren wurden FEM-Simulationen (Finite Element Methode) mit dem gemessenen und dem voreingestellten WDK durchgeführt und daraus der Kristallinitätsgrad und die Bauteildichte gewonnen. Der Vergleich zwischen den realen Ergebnissen und der Simulation zeigt, dass die Berechnungen mit dem gemessenen WDK eine bessere Übereinstimmung mit den realen Werten aufweist, was die Zuverlässigkeit und Präzision der Spritzgusssimulation bestätigt. Die Ergebnisse dieser Arbeit tragen zum umfassenden Verständnis des Wärmeübergangs im Spritzgießprozess, zur Vorhersage der Temperaturverteilung, zur Auslegung des Kühlsystems, zur Reduzierung der Zykluszeit und zur Verbesserung der Genauigkeit der numerischen Simulation bei.
477

Otimização no planejamento agregado de produção em indústrias de processamento de suco concentrado congelado de laranja

Munhoz, José Renato 22 June 2009 (has links)
Made available in DSpace on 2016-06-02T19:50:05Z (GMT). No. of bitstreams: 1 2520.pdf: 1207796 bytes, checksum: d7395bbee81744b10cc9081ce73234c4 (MD5) Previous issue date: 2009-06-22 / This work aim at developing models using linear programming, goal programming and robust optimization to support decision making in the frozen concentrated orange juice planning process. The proposed model includes orange harvesting plan, which takes into account oranges maturation curves. This fact leads to a model that incorporates a large portion of the supply chain involved in the frozen concentrated orange juice sector. Another point to highlight is the inclusion of the blending process of different types of juices to match ratio specification of the product. This study uses orange acidity to calculate ratio specification of the product. This study also explores the importance of data uncertainty incorporation to the aggregate production planning for this business and evaluate results from different approaches of robust optimization to this problem. This author is not aware of previous work in the literature with such approach to the orange juice industry. The problem modeling uses blending problem concepts and production planning with multiple products, stages and periods concepts as well. To solve the linear programming, goal programming and robust optimization models, an algebraic modeling language and a state of art optimization solver of mathematical programming problems is used. A case study was developed in an orange juice company located in the São Paulo State. This company has many facilities and a worldwide distribution system, similar to other companies in this sector. The results show that the proposed approach can be used in real situations. / O objetivo deste trabalho é desenvolver modelos de programação linear, programação por metas e otimização robusta para apoiar decisões no processo de planejamento agregado da produção de suco concentrado congelado de laranja. A modelagem proposta incorpora o planejamento de colheita da laranja, levando-se em consideração as curvas de maturação das laranjas. Esse fato conduz a um modelo que incorpora grande parte da cadeia de suprimento envolvida no setor de produção de suco concentrado congelado de laranja. Outro ponto a destacar é a consideração do processo de mistura de diferentes tipos de sucos para a obtenção da especificação de ratio do produto acabado. No caso desse estudo, utiliza-se a acidez da laranja como base de cálculo para a especificação de ratio do produto acabado. Este estudo também explora a importância da incorporação de incerteza a determinados parâmetros envolvidos no processo de planejamento de produção nesse setor e analisa os resultados das diferentes abordagens de otimização robusta para o problema. Sendo que, este autor desconhece trabalhos anteriores na literatura com esta abordagem para a indústria de suco de laranja. A modelagem do problema utiliza conceitos de problemas de mistura e planejamento de produção com múltiplos produtos, estágios e períodos. Para resolver os modelos de programação linear, programação por metas e otimização robusta, utilizou-se uma linguagem de modelagem algébrica e um aplicativo de última geração de solução de problemas de programação matemática. Um estudo de caso foi realizado em uma empresa de suco de laranja localizada no Estado de São Paulo, envolvendo várias plantas e com uma rede de distribuição internacional com características típicas de outras empresas do setor. Os resultados indicam que a abordagem aqui proposta pode ser aplicada em situações reais.
478

Manual para o desenvolvimento de embalagens de alimentos preparados congelados / Handbook for development of packaging for ready-made frozen food

Rodrigues Júnior, Harry 29 February 2016 (has links)
CNPq / Mudanças nos hábitos alimentares, nas políticas de segurança alimentar e nos estilos de vida da população tem modificado os padrões de projeto das embalagens dos alimentos. Estas mudanças são visíveis especialmente nas funções das embalagens que precisam dar conta da diversidade de oferta de alimentos congelados preparados, denominados alimentos preparados. No contexto do desenvolvimento de embalagens, questiona-se a necessidade de aprofundar a pesquisa nas funções das embalagens para essas categorias de produtos, identificando parâmetros que atendam suas especificidades. E ainda, considerando o cenário produtivo, a análise daquelas já disponíveis no mercado. Para mapear o contexto de projeto de produto, esta investigação busca delimitar as principais funções e características exigidas das embalagens de alimentos congelados preparados, bem como os métodos e práticas de projeto e o cenário de regulamentação dos órgãos normatizadores de segurança alimentar dos alimentos embalados. Como resultado dessa investigação foi elaborado um manual de referência para profissionais envolvidos na estratégia e projeto para o segmento - designers industriais e projetistas de embalagens - de modo a integrar ações, normas e métodos de projeto de produto. Uma amostragem desses perfis profissionais esteve envolvida na pesquisa com usuários e avaliação do manual e os resultados apontaram a necessidade de interlocução entre as áreas (de projeto/alimentos), reforçando a carência de materiais de referência que reúnam, de forma objetiva e sistemática, mecanismos de apoio aos responsáveis pelas análises e validações de embalagens para alimentos preparados congelados. / Changes in eating habits, the food security policies and people's lifestyles have modified food packages of design standards. These changes are visible especially in the functions of the packages that need to account for the diversity of supply of prepared frozen foods, prepared foods called. In the development of packaging, we question the need for further research into the functions of packaging for these product categories, identifying parameters that meet their specific requirements. Further, considering the manufacturing scenario, the analysis those already available on the market. To map the product design context, this research seeks to define the main functions and characteristics required of prepared frozen food packaging, as well as the methods and design practices and regulatory setting of the standard-setting bodies for food safety of packaged food. As a result of this investigation has produced a reference manual for professionals involved in strategy and design to the segment - industrial designers and packaging designers - to integrate actions, standards and product design methods. A sampling of these professional profiles has been involved in research with users and manual evaluation and the results showed the need for dialogue between the areas (design / food), reinforcing the lack of reference materials, comprising an objective and systematic way, mechanisms support those responsible for analysis and packaging validations for frozen prepared foods.
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Variation de l'épigénome, du phénotype et des stratégies écologiques pour la persistance d'un vertébré asexué

Leung, Christelle 11 1900 (has links)
La capacité à répondre aux changements environnementaux est cruciale pour l’établissement et la persistance des populations dans un système hétérogène. Les processus sous-jacents à cette capacité peuvent prendre différentes formes. La grande diversité génétique (et phénotypique) découlant de la reproduction sexuée est un des processus permettant à une population de répondre aux différentes conditions environnementales par la survie d’au moins quelques individus. D’autre part, les processus épigénétiques, en permettant la modification du patron d’expression des gènes, contribuent également à la variation phénotypique. Ces variations peuvent survenir accidentellement (épimutations) ou en réponse à un stimulus environnemental (plasticité). Les processus épigénétiques représenteraient ainsi une alternative à la variation génétique pouvant expliquer le succès écologique des organismes génétiquement identiques. Toutefois, les génotypes ne répondent pas tous de la même façon aux conditions environnementales ; certains génotypes sont considérés comme généralistes et peuvent s’acclimater à une vaste gamme de conditions environnementales alors que d’autres sont plutôt spécialistes et restreints à un type d’environnement donné. L’objectif général de cette thèse est de mettre en évidence certains des processus responsables de la persistance des organismes asexués en déterminant les relations entre la variation épigénétique, la variation phénotypique et les stratégies écologiques. Pour ce faire, des hybrides asexués Chrosomus eos-neogaeus, un poisson à reproduction clonale, ont servi de modèle biologique. Se reproduisant par gynogenèse, les lignées clonales (génotypes) doivent faire face aux mêmes variations environnementales que les espèces parentales sexuées. De plus, la répartition géographique de chacune des lignées suggère la présence de génotypes généralistes et spécialistes. L’analyse de ces lignées en milieux naturels et en milieux contrôlés a permis de décortiquer l’influence des variations génétique, environnementale et épigénétique sur la variation phénotypique. Dans un premier temps, les modèles de stratégies généraliste et spécialiste ont été testés de manière empirique : (i) des analyses génétiques ont permis d’inférer les processus historiques expliquant la diversité et la répartition actuelle des lignées clonales ; (ii) l’analyse du patron de ii méthylation de différentes lignées a permis de déterminer l’importance relative des sources de variations épigénétiques selon les fluctuations environnementales et de les associer à une stratégie écologique : une importante influence de l’environnement ou une plus grande stochasticité dans l’établissement des marques épigénétiques étant associées à la plasticité phénotypique ou au bet-hedging, respectivement ; et (iii) le rôle de la plasticité phénotypique dans la diversification de niches écologiques a été souligné par la comparaison de la variation de la morphologie trophique en milieux naturels et contrôlés. D’autre part, le second volet de cette thèse a permis d’associer un coût (détection d’une instabilité développementale) à la plasticité phénotypique et d’élaborer une hypothèse sur l’existence d’un handicap démographique nécessaire afin d’expliquer la situation contre-intuitive concernant la coexistence des organismes gynogènes et de leurs hôtes sexués. La compréhension des différents mécanismes sous-jacents au succès écologique des organismes face aux variations environnementales permet ainsi une meilleure évaluation de leur potentiel évolutif et fournit des outils supplémentaires pour leur protection face à un environnement changeant. / The capacity to cope with environmental changes is crucial to the establishment and persistence of populations. The processes underlying such a capacity can take different forms. The high genetic (and phenotypic) diversity arising from sexual reproduction is one process that allows to cope with different environmental conditions through the survival of at least a few individuals. On the other hand, epigenetic processes, allowing the modification of gene expression, are also responsible for phenotypic variation. Epigenetic changes may occur accidentally (epimutations) or in response to an environmental stimulus (plasticity). Thus, epigenetics would represent an alternative process to genetic variation to explain the ecological success of genetically identical organisms. However, genotypes are not equally capable of coping with environmental changes. Some genotypes are generalists and can acclimatize to a wide range of environmental conditions, whereas other genotypes are specialized and restricted to narrow environmental conditions. The general objective of this thesis is to highlight the processes responsible for the persistence of asexual organisms by determining the relationship between epigenetic processes, phenotypic variation and ecological strategies. To achieve this, the clonal hybrid fish Chrosomus eos-neogaeus were used as a biological model. By reproducing by gynogenesis, the clonal lineages (genotypes) are distributed among the same environments than the sexual parental species. Moreover, the geographical distribution of the lineages suggests the presence of generalist and specialist genotypes. The analysis of these lineages in natural and controlled conditions allowed to disentangling the influence of genetic, environmental and epigenetic variations on phenotypic variation. On the one hand, generalist and specialist strategies were empirically tested: (i) genetic analyses were used to infer the historical processes explaining the diversity and the current distribution of the clonal lineages; (ii) the comparison of methylation patterns in different lineages allowed to determine the dynamism of the epigenetic processes according to environmental fluctuations and to associate them with an ecological strategy: an important environmental or stochastic effect on epigenetic variation being associated with phenotypic iv plasticity or bet-hedging, respectively; and (iii) the role of phenotypic plasticity in niches diversification was highlighted by comparing individuals’ trophic morphology in natural and controlled conditions. On the other hand, the second part of this thesis has allowed to associate a cost (developmental instability) to phenotypic plasticity and to propose a hypothesis about the existence of a demographic handicap necessary to explain the paradox regarding the coexistence of sexual and asexual sperm-dependent organisms. Understanding these different mechanisms underlying the ecological success of organisms in face of environmental heterogeneity allows us to better establish their evolutionary potential and provides additional tools to protect them against changing environments.
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Obtenção e caracterização de Minced Fish de sardinha e sua estabilidade durante a estocagem sob congelamento / Obtaining and characterization of Minced Fish sardines and its stability during storage under freezing

Cristiane Rodrigues Pinheiro Neiva 06 June 2003 (has links)
É muito elevado o potencial de utilização do pescado na forma de minced fish - MF, servindo de matéria-prima para outros produtos. O MF de sardinha foi avaliado quanto ao rendimento, ao efeito da lavagem sobre a melhoria da cor, à caracterização química e quanto à estabilidade química e sensorial durante estocagem sob congelamento de -17 a -18°C. O rendimento do MF de sardinha lavado com água foi de 55% em relação ao peixe inteiro e próximo do rendimento teórico da parte comestível. A lavagem do MF com água ou água + bicarbonato de sódio proporcionou a obtenção de um produto com cor vantajosamente mais clara e apreciável. Com relação à composição química básica o MF de sardinha lavado com água apresentou maior hidratação e menor teor de cinzas em relação ao controle e semelhantes quantidades de proteína e lípides. Comparado ao controle, o MF de sardinha lavado com água, não apresentou diferença quanto ao perfil de ácidos graxos e pH, o que não ocorreu com o nitrogênio das bases voláteis - N-BVT, que diminuiu, e às substâncias reativas ao ácido tiobarbitúrico - TBARS, que aumentaram. O MF de sardinha lavado com água, contendo ou não antioxidantes artificialmente adicionados, apresentou estabilidade química e sensorial quando mantido sob congelamento, com base nos parâmetros pH, N-BVT, TBARS, odor a ranço e cor, em até 26 semanas de estocagem. Os resultados do presente trabalho são favoráveis à possibilidade de obtenção de MF de sardinha lavado com água e seu emprego como matéria-prima para outros produtos pesqueiros. / The potentiality of fish\'s utilization as minced fish - MF is very high, actually turning into a raw material to other products. The sardine\'s MF was evaluated according to its yield, the washing effect improving the color, its chemical characteristic and chemical and sensorial stability, during frozen storage under -17,-18°C. The yield of sardine\'s MF washed in with water, was 55% related to the whole fish and close to the theoretic yield of eatable portion. The MF\'s washing in water or in water plus sodium bicarbonate provide a product with clearer and more desirable color. Related to the chemical basic composition, sardine\'s MF washed in water, presented better hydration and lower ashes contents than its control, and similar quantity of protein and lipids. Compared to the control, the sardine\'s MF washed in water, had not presented any difference related to the fatty acids profile and pH, that had not happened with the nitrogen of volatile bases - N-BVT, which had been decreased, and the thiobarbituric acid reactant substances - TBARS, that had been increased. The sardine\'s MF washed in water, containing or not added antioxidants, was chemical and sensorial stable when maintained frozen, based on parameters as pH, N-BVT, TBARS, rancidity odor, and color, stored for 26 weeks. The results of this work are propitious to the possibility of achieving sardine\'s MF washed in water, and your utilization as a raw material to others seafoods.

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