Добірка наукової літератури з теми "Reologické parametry"

The aim of this research was the investigation of winter wheat varieties, the kernel hardness and the dough features. We determined the kernel hardness with two dynamic methods. We measured the parameters of flour. The correlations among hardness index and the examined flour parameters were also significant (r=0.816-0.876). We found strong correlation between the grinding energy (eg) and water absorption (r=0.878) of the flour. Hardness Index – wet gluten (r=0.833), and Hardness Index – water absorption (r=0.876), Hardness Index – P value of alveograph (r=0.816) showed also positive correlations. We found correlation the water absorption and P value of alveograph (r=0.873).

In this paper, the modeling, analysis and monitoring of a room-and-pillar mining technology in an Estonian underground mines is presented. Technology is based on continuous miner as the primary production machine. Many technical and economic parameters o f production, including loss of useful minerals, depend on a correct choice of the sizes for these elements. Without the account o f reological properties o f covered rocks, in particular the character of change o f their long strength, the account of the sizes of rooms and pillars on a certain determined term is impossible. For the modeling, the existing room- and-pillars determination method by IMS and with formulas by V. Undusk, Visual Basic for Application in Excel, Maplnfo, and Fast Lagrangian Analysis of Continua was used. Model allows determining the parameters of spontaneous collapse of the pillars and\ surface subsidence, optimized the working parameters for continuous mining. Proposed method suits for stability analysis, failure prognosis and monitoring.

The aim of this study was to develop granules from Phyllanthus niruri spray-dried extract using dry and wet granulation and to assess techniques to enable the production of granules with improved technological characteristics and yields. Granules were characterized by granulometry, reological parameters, compression and hygroscopic behavior. Independent of the granulation technique, technologically developed granules presented particle diameter, bulk and tapped densities and compressibility indexes suitable for a solid dosage form. The compression behavior showed plastic and fragmentary deformation for granules produced by the dry granulation technique and predominantly plastic deformation for wet granulation. Concerning the humidity sorption, the study showed that granules absorb less humidity than the spray-dried extract. However, granules with Eudragit® E 100 were the least hygroscopic.

Chocolate is a complex rheological system in which non-fat cocoa particles and sugar particles are enveloped by crystal matrix of cocoa butter. Physical properties of chocolate depend on ingredient composition, method of production and properly performed pre-crystallization phase. In this work, chocolate was produced in an unconventional way, i.e. in a ball mill applying variable refining time (30, 60 and 90 min) and pre-crystallization temperature in chocolate masses (26, 28 and 30?C). Two types of chocolate were produced: chocolate with 20% of powdered cow?s milk (R1) and chocolate with 20% of soya milk powder (R2). The quality of chocolate was followed by comparing nutritive composition, 23 polyphenol content, hardness of chocolate, solid triglyceride content (SFC) and rheological parameters (Casson yield flow (Pa), Casson viscosity (Pas), the area of the thixotropic loop, elastic modulus and creep curves). The aim of this paper is determining changes caused by replacing cow?s milk with soya milk powder in respect of nutritive, rheological and sensory properties, as well as defining optimal parameters: precrystallization temperature and refining time of soya milk chocolate in order to obtain suitable sensory and physical properties identical to those of milk chocolate mass. The results show that replacing powdered cow?s milk with soya milk powder affects the increase in nutritive value of soya milk chocolate. R2 chocolate mass showed the increase in essential amino acids and fatty acids. This chocolate mass also showed the increase in total polyphenols by 28.1% comparing to R1 chocolate mass. By comparing viscosity, yield stress, shear stress and the area of the thixotropic loop, it can be observed that R1 chocolate mass represents a more organized and simpler system than the mass with soya milk (R2), as it shows lower values for all the above mentioned parameters, regardless of the refining time and pre-crystallization temperature. Viscoelastic behavior of R2 is also evident, as a consequence of soya protein presence. In order to maintain optimal hardness as well as melting resistance of chocolate, in case of R2 chocolate mass it is necessary to apply pre-crystallization temperature of 26?C, while for the chocolate mass R1 it is 30?C.

Grape skin is considered a valuable by-product for antioxidant and antibacterial agent preparation. The grape skin contains some active compounds, such as, dietary fiber, polyphenols, flavonols, and resveratrol; it is commonly used as a nutritional supplement. The main aim of this study was to establish the optimum dose of grape skin flour, to be used as a functional ingredient in the bakery products industry, from both chemical and rheological point of view. The laboratory experiments evaluated the functional potential of wheat flour enriched with grape skin flour, in different proportions, by examining the chemical composition and rheological behaviour of the doughs. Protein, crude fibre, fat, ash and mineral contents were determined. Using �H-NMR spectral technique, the fatty acids composition was determined, especially the concentrations of short-chain saturated fatty acids (C4-C8), di-unsaturated fatty acids, mono-unsaturated fatty acids and long-chain saturated fatty acids (]C8). 1H-NMR spectra were recorded on a Bruker Ascend 400 MHz spectrometer. The rheological behaviour was analyzed using the predefined Chopin + protocol on Mixolab, an equipment of CHOPIN Technologies. Grape skin flour was incorporated into wheat flour at three different levels, 5, 10 and 15% and it was found that incorporation up to a 15% level into the formulation of wheat flour yielded an acceptable product in terms of rheological parameters, with improved chemical, nutritional and functional properties.

The results of three-year trials (1999 to 2001) conducted with six winter wheat varieties in which was investigated the effect of sites, years and varieties on the final grain yield and technological quality showed statistically significant differences (LSD, 95%) among sites in grain yield and these parameters of quality: test volume mass, wet gluten content, sedimentation test, protein content, falling number and flour water absorption capacity. As to the quality, the Žatec site showed itself as generally most suitable, and the Jaroměřice site as the least suitable one. Climate conditions showed a statistically significant effect (LSD, 95%) on grain yield and all quality parameters, beside the percentage of complete grains and swelling capacity of gluten and falling number, which were insignificant. The most favourable weather conditions, a lot of precipitation and high temperature in the course of ripening from three years were proved in the year 2000. Among the varieties were statistically significant differences (LSD, 95%) in grain yield and these parameters of quality: test volume mass, thousand grain weight, ash content, percentage of complete grains, sedimentation test, protein content, reologic properties of dough and baking tests. From the six varieties the best profits were shown from variety Sulamit (loaf volume 595 ml/100 g of flour), the worst was Semper (loaf volume 543 ml/100 g of flour) and Vlasta (loaf volume 532 ml/100 g of flour). The best grain yield was in 2001 (average of sites 8.84 t/ha) and the variety Semper had the highest grain yield of 9.17 t/ha, that is higher at 13.41% compared with Sulamit (7.94 t/ha).

Wheat is one of the most important cereals in the world and the bread made of its flour belongs to the everyday life of human mankind.The Hungarian standard relating to the laboratory production of wheat flour (MSZ 6367/9-1989) does not mention the type of laboratory mill used for milling, and it only builds up some general criteria, such as: the laboratory mill should be provided with four differently nicked barrels, a sieve with appropriate hole sizes, and also with the separated collections of the pilot flour and the bran. Our study was started at this point and the answers for the following questions were aimed to be found: do the flour patterns studied and produced with different grinding and sievingtechniques, widely used in laboratory mills of the same wheat pattern show any alterations after the impact of the formula production as regards chemical constitutions and reologic parameters. Various flours and whole grains of the wheat patterns sieved with different particle sizes were studied in this experiment. In producing this pattern two different mill types of FQC 109 and CHOPIN CD 1 as well as two different grinder types such as PERTEN 3100 and type of RETSCH 200 were applied. There were 3 different corn sizes of 160; 250; 800 μms used in the partition of the fractions. To study the differences the following measurements were conducted: dry matter, ash, protein content, wet gluten content, gluten index, gluten expansiveness, farinographic value, falling number and amilographic rate.The results this research confirm that the quality of wheat flour can be modified by different methods of pattern production. In all cases the differences can be explained by the flour-bran ratio, and in some of the cases the higher germ content of the fractions also played a role. The results show differences between the various types of mills and grinders, too.

Tato diplomová práce se zabývá aktuálními poznatky, společně s optimalizací oscilačních měření pomocí hybridního reometru, ale hlavně pozorováním změn reologických parametrů v čase past mleté granulované vysokopecní strusky aktivované různými aktivačními roztoky s koncentrací alkálií M: 4 and 7.5 moldm. Výsledky byly pro diskuzi podpořeny výstupy z Vicatovy metody a izotermické kalorimetrie. Nejprve bylo zjištěno, že limit lineární viskoelastické oblasti se zmenšuje v čase. Dále bylo pozorováno, že v time sweep testech vykazovala struska aktivovaná křemičitany nejnižší hodnoty komplexního modulu a struska aktivovaná hydroxidy o koncentraci 4 moldm nejvyšší hodnoty a ostatní pasty vykazovaly hodnoty mezi těmito dvěma extrémy a měly mezi sebou porovnatelné hodnoty. Podobný trend byl pozorován u vývoje kritické meze oscilačního napětí, získaného z amplitude sweep testů (přerušovaně a nepřerušovaně). Oba výše zmíněné parametry, komplexní modul a mez napětí, se vyvíjely v čase. Výsledky všech testů jasně ukázaly, že povrchová chemie hraje roli ve výsledném reologickém chování. Odsud, povaha a koncentrace aktivátoru ovlivňují reologické vlastnosti skrze efekty Na a K iontů, stejně tak skrze koncentraci, která má dopad na elektickou dvojnou vrstvu. Reologické chování může být také ovlivněno dalšími faktory, např. viskozitou aktivačního roztoku a celkovou kinetikou hydratačního procesu.

Orientador: Cesar Costapinto Santana
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A industria química e também a área de prospeção de petróleo utilizam freqüentemente muitas suspensões sólido-líquido de comportamento reológico não-newtoniano com tensão residual, que é um valor crítico abaixo do qual o fluido escoa sem deformação. Essa característica exige o uso de modelos reológicos mais sofisticados para descrever o seu comportamento fluido-dinâmico. As circunstâncias normalmente verificadas na prática requerem que as correlações usadas para descrição do fenômeno acima citado sejam capazes de prever o comportamento do escoamento abrangendo as condições dos regimes laminar, transição e turbulento. O presente trabalho apresenta uma formulação matemática que visa obter correlações que atendam a necessidade das aplicações práticas. Para tanto, realizou-se o estudo detalhado da utilização de um modelo reológico a três parâmetros( Modelo de Robertson & Stiff) para a análise do escoamento anular em tubulações, tendo sido elaboradas novas definições de números de Reynolds e de Número de Hedstrom. Para o escoamento laminar são apresentadas correlações para o coeficiente de atrito em função do Número de Reynolds de Robertson & Stiff, contendo um parâmetro adicional que considera a influência da tensão residual. Nessas correlações tembém estão incluídos parâmetros constantes para cada geometria de escoamento. Na região de escoamento de transição, o trabalho apresenta uma formulação matemática inédita, utilizando o modelo reológico de transição ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Several solid-liquid suspensions frequently encountered in chemical industry and also in oil well drilling operations exhibit a non-Newtonian behavior with an yield stress, a critical value of stress below which they do not flow. Due to the real conditions usually verified, it is important to master calculations techniques involve the laminar also the transitional and turbulent flow regimes. This thesis consists of an unpublished work presenting an inedit mathematical formulation in order to propose correlations of practical use. The realized study of the annular flow between concentric pipes was based on Robertson and Stiff¿s rheological model, which is a three parameters equation, and on new definitions of Reynolds and Hedstrom numbers. The proposed correlations to the factor friction to Robertson and Stiffi¿s Reynolds number in laminar flow involves one additional parameter considering the yield stress effects and a second one including also he flow geometry. The transitional flow study resulted in a inedit theorical formulation usisng Robertson and rheological model that enables the transitional point or region prediction. This procedure led to a system of highly non-linear equations and its numerical model that enables the transitional point or region predction. This procedure led to a system of highly non-lnear equation and its numericar solution is presented in a table ...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Mestrado
Mestre em Engenharia Química

Název: Vliv operační techniky u diagnózy "Ruptura LCA" na vybrané reologické parametry. Title: Influence of surgical technique in ACL rupture on selected rheological parameters of the knee. Cíl práce: Zhodnocení a porovnání změn reologických vlastností kolenního kloubu u ruptury předního zkříženého vazu před a po jejím chirurgickém ošetření a v průběhu rekonvalescence. Metoda: Experimentálního in vivo měření pasivního odporu kolenního kloubu při vynuceném pohybu do flexe a extenze metodou bioreometrie. Zhodnocení specifických reologických vlastností, které vystihují momentální stav kolenního kloubu. Vyhodnocení naměřených dat pomocí grafického znázornění sumárních reologických charakteristik - bioreogramu. Výsledky: Výsledky odhalují průběh rekonvalescence u pacientů po plastice předního zkříženého vazu. Tento průběh zachycuje specifické změny reologických charakteristik kolenního kloubu během tří měsíců, které byly patrné při vyhodnocování bioreogramů. Byly zjištěny změny tvaru křivek, které vypovídají o změnách tuhosti, disipované energie a tím i "účinnosti" kolenního kloubu během léčebného procesu. Výsledky naznačily možnost budoucího hodnocení poruch kolene právě metodou bioreometrie. Klíčová slova: bioreogram, bioreometrie, kolenní kloub, přední zkřížený vaz, rekonstrukce kolenního kloubu,...

Název: Vliv chirurgického ošetření poraněné nitrokloubní chrupavky kolenního kloubu na vybrané reologické parametry Title: Influence of surgical treatment injured arthral cartilage of the knee joint on selected rheological parameters Cíle práce: Cílem diplomové práce je pomocí bioreodiagnostiky porovnat změny reologických vlastností kolenního kloubu po poškození chrupavky a po jejím chirurgickém ošetření. Získat přehled o problematice poranění chrupavky kolenního kloubu a možnostech chirurgického ošetření. Metoda: Měření bylo provedeno pomocí bioreometru, naměřené hodnoty zpracovány a vyhodnoceny ve formě bioreogramů. Bioreometr měří in vivo mechanický odpor vznikající v kolenním kloubu během pasivního pohybu do flexe a extenze kolena. Práce je zpracována na třech jedincích s diagnostikovanou lézí chrupavky kolenního kloubu. Výsledky: Výsledky odhalily změny v charakteru tvaru a vlastností bioreogramů před a po chirurgickém ošetření kloubní chrupavky. Bioreogramy zachycují vývoj reologických vlastností kolenních kloubů v průběhu všech tří měření a poukazují na možnost detekce jejich změn. Klíčová slova: kolenní kloub, chrupavka kolena, reologie, bioreometrie, bioreogram Alžběta Starková, 13. 4. 2010