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Studium chování betonů při působení vysokých teplot
Čonka, Ladislav ; Sitek,, Libor (oponent) ; Bodnárová, Lenka (vedoucí práce)
Diplomová práce je zaměřena na aktuální problematiku odolnosti betonů vůči působení vysokých teplot. V teoretické části byly zpracovány změny, probíhající v jednotlivých složkách betonů a změny, ovlivňující fyzikálně – mechanické vlastnosti betonu a barevné změny projevující se působením vysoké. Diplomová práce je zaměřena na aktuální problematiku odolnosti betonů vůči působení vysokých teplot. V teoretické části byly zpracovány změny, probíhající v jednotlivých složkách betonů a změny, ovlivňující fyzikálně – mechanické vlastnosti betonu a barevné změny projevující se působením vysoké.
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Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications
Fajtl, Zdeněk ; Omelka, Ladislav (oponent) ; Polovka, Martin (vedoucí práce)
Fruit juices belong to the most popular drinks worldwide. Besides vitamins and minerals they represent rich source of phenolic compounds recognized for their antioxidant activity. Increasing consumer’s demands towards high quality and safe food products push their producers to increase the production and qualitative standards of the products. Recent innovations in juices production resulted in modification of production conditions, comprising the modification of composition (e.g., addition of fruit pulp and/or small fruit pieces) innovations in packaging materials and the production atmosphere modification. In the diploma thesis, the effects of production conditions of fresh orange juices with pulp and pineapple juices and their modification, as well as the effect of conditions of their long-term storage on selected qualitative characteristics (antioxidant activity, color changes and concentration of selected phytochemicals) are assessed and evaluated dominantly by EPR and UV-VIS spectroscopy. Results obtained were processed by multivariate statistics in order to evaluate the effects of sample origin and season or production technology on the monitored characteristics and overall quality of fruit juices. Results obtained indicated that pasteurization influence the quality of the product, although the slight pasteurization was applied, as in comparison to the fresh – non-pasteurized samples, slight decrease of values of the monitored parameters was observed. However, as regards the post-pasteurization changes, significant influence of the production atmosphere on the monitored qualitative parameters of juices was noticed, proving that replacement of oxygen by inert gases prolongs significantly the juices shelf live. Kinetic study of the changes of the monitored parameters upon the storage period indicate that in majority of cases, gradual worsening of all the monitored parameters was observed, without respect on technology of juice processing. In the samples processed under the modified atmosphere, generally the retardation of the decrease as a result of inert atmosphere application in dependence on type of production gas was noticed. This trend was particularly obvious for longer storage periods, whereas in the beginning of storage (6 - 7 weeks after production), the observed trends were unambiguous. Thus, it can be supposed that this “protecting” effect of inert atmosphere is influenced by the physico-chemical properties of gases, mostly by their solubility in the liquid juice medium. It was also proved, that the properties of juices, are significantly affected by the effects of season and raw juice origin. As follows from the results of statistical analysis, the year of production is strong discriminant factor as on the basis of all the monitored characteristics, absolute discrimination of the samples by canonical discrimination analysis was achieved. As regards raw material origin, only partial differentiation, although with high classification score was obtained. As regards the effect of production technology, the partially successful differentiation of samples according to the inert gas applied was obtained. The obtained results will help the juice producer in optimization of the juice production conditions in order to obtain the product with maximum beneficial properties kept during the whole expiration period. Its length can also be optimized on the basis of the presented results.
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Studium chování betonů při působení vysokých teplot
Čonka, Ladislav ; Sitek,, Libor (oponent) ; Bodnárová, Lenka (vedoucí práce)
Diplomová práce je zaměřena na aktuální problematiku odolnosti betonů vůči působení vysokých teplot. V teoretické části byly zpracovány změny, probíhající v jednotlivých složkách betonů a změny, ovlivňující fyzikálně – mechanické vlastnosti betonu a barevné změny projevující se působením vysoké. Diplomová práce je zaměřena na aktuální problematiku odolnosti betonů vůči působení vysokých teplot. V teoretické části byly zpracovány změny, probíhající v jednotlivých složkách betonů a změny, ovlivňující fyzikálně – mechanické vlastnosti betonu a barevné změny projevující se působením vysoké.
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Analýza vývoje barevných změn krajiny
Uhrovičová, Alena ; Vacek, Oldřich (vedoucí práce) ; Klára, Klára (oponent)
Tato práce popisuje působení barev na člověka a pozoruje zastoupení jednotlivých
barev v krajině. Zabývá se psychologií a vnímáním těchto barev člověkem. Prostor je dán
fenologii, která zkoumá každoročně se opakující projevy orgánů rostlin u jednotlivých
vývojových fází. V práci je taktéž popsána fytocenologie, neboli mapování výskytu druhů a
hodnocení pokryvnosti porostu. Vcelku konkrétně jsou zde vysvětleny i barevné modely.
Metodická část je zaměřena na sledování barevné proměny vybraného místa, ležícího
v oblasti Šumavy, v průběhu jednoho vegetačního období. Tato proměna je zdokumentována
pomocí 12 fotografií a následně ověřena a vyhodnocena prostřednictvím metody analýzy
časosběrných snímků. Cílem snímkování je navrhnout objektivní způsob hodnocení
barevných změn, které se během vegetačního roku v krajině odehrávají. Hypotézou ověříme,
zda lze sezonní změny v krajině objektivně hodnotit.
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Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications
Fajtl, Zdeněk ; Omelka, Ladislav (oponent) ; Polovka, Martin (vedoucí práce)
Fruit juices belong to the most popular drinks worldwide. Besides vitamins and minerals they represent rich source of phenolic compounds recognized for their antioxidant activity. Increasing consumer’s demands towards high quality and safe food products push their producers to increase the production and qualitative standards of the products. Recent innovations in juices production resulted in modification of production conditions, comprising the modification of composition (e.g., addition of fruit pulp and/or small fruit pieces) innovations in packaging materials and the production atmosphere modification. In the diploma thesis, the effects of production conditions of fresh orange juices with pulp and pineapple juices and their modification, as well as the effect of conditions of their long-term storage on selected qualitative characteristics (antioxidant activity, color changes and concentration of selected phytochemicals) are assessed and evaluated dominantly by EPR and UV-VIS spectroscopy. Results obtained were processed by multivariate statistics in order to evaluate the effects of sample origin and season or production technology on the monitored characteristics and overall quality of fruit juices. Results obtained indicated that pasteurization influence the quality of the product, although the slight pasteurization was applied, as in comparison to the fresh – non-pasteurized samples, slight decrease of values of the monitored parameters was observed. However, as regards the post-pasteurization changes, significant influence of the production atmosphere on the monitored qualitative parameters of juices was noticed, proving that replacement of oxygen by inert gases prolongs significantly the juices shelf live. Kinetic study of the changes of the monitored parameters upon the storage period indicate that in majority of cases, gradual worsening of all the monitored parameters was observed, without respect on technology of juice processing. In the samples processed under the modified atmosphere, generally the retardation of the decrease as a result of inert atmosphere application in dependence on type of production gas was noticed. This trend was particularly obvious for longer storage periods, whereas in the beginning of storage (6 - 7 weeks after production), the observed trends were unambiguous. Thus, it can be supposed that this “protecting” effect of inert atmosphere is influenced by the physico-chemical properties of gases, mostly by their solubility in the liquid juice medium. It was also proved, that the properties of juices, are significantly affected by the effects of season and raw juice origin. As follows from the results of statistical analysis, the year of production is strong discriminant factor as on the basis of all the monitored characteristics, absolute discrimination of the samples by canonical discrimination analysis was achieved. As regards raw material origin, only partial differentiation, although with high classification score was obtained. As regards the effect of production technology, the partially successful differentiation of samples according to the inert gas applied was obtained. The obtained results will help the juice producer in optimization of the juice production conditions in order to obtain the product with maximum beneficial properties kept during the whole expiration period. Its length can also be optimized on the basis of the presented results.
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