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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.
61

Obtenção de cerveja super concentrada com a utilização de xarope de milho como adjunto de malte / Obtaining super concentrated beer using corn syrup as adjunct of malt

Orerves Martinez Castro 06 May 2014 (has links)
Este trabalho teve por objetivo a utilização de xarope de milho na elaboração de cerveja super concentrada. Para atingir este propósito foram realizados ensaios em escala de 5 litros, testando três proporções quanto à relação de extrato de malte e de xarope de milho. Para seguir a legislação brasileira de acordo com o Decreto 6.871, de 2009, foram propostos para a realização dos experimentos as proporções de 70/30, 55/45 e 20/80 de malte:xarope de milho. Na proporção 20/80, definida pelo referido Decreto como cerveja de milho foram avaliadas diferentes variantes para obter diferentes concentrações alcoólicas, obtendo resultados inadequados. As fermentações foram conduzidas em regime descontínuo alimentado, com a adição do xarope por cargas, e foi utilizada uma levedura com alta eficiência fermentativa que tem demonstrado alta tolerância a concentrações de álcool, classificada como PPB - 01. Para comparar com os mostos experimentais, foram elaborados mostos padrões nas proporções 70/30 e 55/45. Em escala piloto foi elaborada uma prova de cerveja super concentrada, para as proporções 70/30 e 55/45, malte/milho. Foram avaliados os parâmetros cinéticos dos processos. As eficiências de formação de álcool e de consumo de extrato foram acima dos 90%, o que garantiu um bom processo fermentativo. As cervejas obtidas na escala piloto foram submetidas a análises sensoriais e comparadas com uma cerveja comercial, obtendo ótimos resultados. As duas proporções aprovadas proporcionaram economia de energia térmica e elétrica, quando comparadas com as cervejas padrões. Os resultados obtidos no projeto demonstraram que é possível a aplicação desta tecnologia, aumentando a produtividade utilizando os mesmos equipamentos e obtendo benefícios energéticos, econômicos e meio ambientais. / The aim of this project was the use of corn syrup to develop super concentrated beer. Accomplishing this purpose was made initially two repeat experiments on a scale of 5 liters and testing three variants as regards the relationship of malt extract and corn. Following the Brazilian law in accordance with the Decree 6.871, 2009, was proposed for the realization of experiments the proportions of 70/30, 55/45 and 20/80 from malt and corn. In the proportion 20/80, defined by Decree as corn beer, were evaluated different variants for obtaining different alcohol concentrations, obtaining inadequate results. Fermentations were conducted in fed batch regime with the addition of the syrup in pulses, and was used one yeast with high efficiency of fermentation and tolerating of alcohol high concentrations, classified as PPB - 01. To compare with the experimental worts, were prepared standards worts for proportions 70/30 and 55/45. In pilot scale, were made experiments of super concentrated beer to the proportions 70/30 and 55/45, malt/corn. The kinetic parameters of the processes were evaluated. The efficiencies of formation of alcohol and consumption of extract were above 90%, which ensured a good fermentation. The experimental beers obtained in pilot scale were subjected to sensory analysis compared with a beer sold in trade, getting great results. The two proportions approved had saving thermal and electrical energy, when compared with standards beers. The results obtained in the project demonstrated that it is possible to apply this technology, increasing equipment productivity and getting energy, economic and environmental benefits.
62

Fate of β-Lactoglobulin, α-Lactalbumin, and Casein Proteins in Ultrafiltered Concentrated Milk after Ultra-high Temperature Processing

Alleyne, Mark Christopher 01 May 1994 (has links)
The problem of age gelation in ultra-high temperature (U1IT) sterilized milk retentate (ultrafiltered 3x concentrated) is investigated in this work. Transmission electron microscopy (1EM), utilizing the microcube encapsulation technique and protocols for immunolocalization of milk proteins, provides insight into the phenomenon of age gelation ofUHT-sterilized, ultrafiltered (UF) milk retentate. Primary antibodies (specific for the native as well as the complexed forms of milk proteins) and secondary antibodies (conjugated to gold probes) are used to elucidate the positions of the milk proteins in various samples of milk from the stage of milking through UHT sterilization and storage for 12 months, by which time gelation had occurred. The movement of the milk proteins is charted and these data are used to determine the role of the proteins in age gelation of UHT-sterilized UF milk retentate. Heat-denatured β-lactoglobulin and α-lactalbumin form complexes within the serum as well as with the casein components of the micelles. UHT sterilization not only denatures β-lactoglobulin and α-lactalbumin, but catalyzes the reaction of these whey proteins and K-casein, leading to the successful formation of the complex. Complexing of β-lactoglobulin and K-casein competitively weakens the complex of K-casein to other casein fractions of the micelle. This leads to migration of K-casein from the micelle to the serum, compromising the role of K-casein in stabilizing the casein proteins within the micellar moiety. The time-dependent loss of K-casein from the micelle would expose the calcium-insoluble micellar αs1-casein and β-casein to the serum calcium. Subsequent to this, some αs1-casein and β-casein are also released from the micelles, and gelation of the milk occurs. No information was obtained on location of αs2-casein. The release of K-casein from the micelles thus apparently represents the critical factor in the phenomenon of age gelation in UHT-sterilized milk concentrates.
63

LASER-TESTING RIG : Measurement System for evaluation of Shape of concentrating reflector for solar collector Absolicon X10

Gaynullin, Bakhram January 2009 (has links)
This Thesis project is a part of the all-round automation of production of concentrating solar PV/T systems Absolicon X10. ABSOLICON Solar Concentrator AB has been invented and started production of the prospective solar concentrated system Absolicon X10. The aims of this Thesis project are designing, assembling, calibrating and putting in operation the automatic measurement system intended to evaluate the shape of concentrating parabolic reflectors.On the basis of the requirements of the company administration and needs of real production process the operation conditions for the Laser testing rig were formulated. The basic concept to use laser radiation was defined.At the first step, the complex design of the whole system was made and division on the parts was defined. After the preliminary conducted simulations the function and operation conditions of the all parts were formulated.At the next steps, the detailed design of all the parts was conducted. Most components were ordered from respective companies. Some of the mechanical components were made in the workshop of the company. All parts of the Laser-testing rig were assembled and tested. Software part, which controls the Laser-testing rig work, was created on the LabVIEW basis. To tune and test software part the special simulator was designed and assembled.When all parts were assembled in the complete system, the Laser-testing rig was tested, calibrated and tuned.In the workshop of Absolicon AB, the trial measurements were conducted and Laser-testing rig was installed in the production line at the plant in Soleftea.
64

Stålbalkars bärförmåga vid intryckning - orsakad av lokal momentbelastning

Hedmark, Per January 2007 (has links)
<p>This master thesis deals with steel girders subjected to patch loading caused by concentrated moments. There exist no good methods to calculate by hand the ultimate resistance for this load case. In “tunnplåtshandboken”, (Handbook for sheet metal, which is published by SSAB), one calculation method is presented. It’s however fairly difficult to use, because of many calculation steps and many graphs. This study concentrates on how to calculate the resistance for this load case in a better way. The load case arises for example when a small steel plate (attachment) is welded to the flange above the web of a girder and the attachment is pulled in a direction parallel to the beam. It’s possible view the load as two components, a moment and a horizontal load. The moment will push the attachment into the girder and finally yielding in combination with web buckling will govern the ultimate resistance. In this report, only the moment part of the load is studied.</p><p>This study was made in three steps. First an FE-model was built. This model was verified against physical tests on patch loading from a force acting perpendicular to the beam axis. This approach was taken because no tests were found for the load case with a local moment. As step number two the FE-model was numerically adjusted to work for tests with patch loading caused by a local moment. A number of experiments were made, for which two parameters were varied, the thickness of the web and the length of the attachment. The loaded attachment was made very stiff, because it should not be deformed in order to simulate a sharp concentrated moment. In the last step a hand calculation model was developed for the investigated load case.</p><p>The FE-model that was created for comparison to the physical experiments gave resistances 10 % below the resistances, from the physical tests. This was mainly due to the sensitivity of the girder to initial imperfections and that the most severe buckling mode was used in the modeling of the imperfections.</p><p>The handcalculation model was developed to imitate the one for patch loading in EN 1993-1- 5 (EC3), because it may then work as an addition to EC3. The model was developed in three steps: yield resistance, critical elastic buckling load and the resistance function. The model for yield resistance is analytical and has a form equivalent to the one in EC3. The expressions for the critical elastic buckling load were taken as simple as possible, since they are the main area of this study. The method essentially uses the same equations as EC3 except from two small changes. The results are on the safe side but the safety margin increases when the length of the loaded attachment decreases and the slenderness of the web panel increase. Consequently formulas for calculating the critical load may be improved. The chosen reduction function was slightly increased compared to the function in EC3 but the results will still have a good safety margin. The complete model gives results where the safety margin increases as the length of the loaded attachment decreases. The calculation model was designed to be easy to use. In comparison to the FE-analysis, all the tested beams except a few with low slenderness gave results on the safe side.</p> / <p>Detta examensarbete behandlar stålbalkar utsatta för lokal intryckning orsakade av en lokal momentbelastning. För lastfallet finns ännu inga bra handräkningsmetoder, i plåthandboken som ges ut av SSAB finns en beräkningsmetod presenterad. Den är väldigt krånglig med många beräkningssteg och diagram. Denna studie är inriktad på att utreda hur man kan räkna på belastningsfallet på ett enklare och bättre sätt. Lastfallet uppkommer t.ex. då en lastögla svetsas till flänsen rakt över livet på en balk. Om lastöglan dras parallellt med balkens riktning så kan belastningen ses som två komponenter, ett moment och en horisontalkraft. Momentet kommer att trycka in lastöglan i balken och till slut blir det ett brott p.g.a. en blandning av att materialet flyter och att livet bucklar. I den här rapporten behandlas bara momentdelen av lasten.</p><p>Studien är gjord i tre steg. Först byggdes en FE-modell i Abaqus. Denna modell verifierades mot fysiska försök på lokal intryckning från en vertikal kraft, eftersom inga försök hittades på intryckning av ett lokalt moment. Som steg nummer två anpassades FE-modellen till försök med lokal intryckning från ett moment. Ett antal experiment gjordes med variation av två parametrar, livplåtens tjocklek och lastöglans längd. Lastöglan var väldigt styv eftersom den bara skulle skapa momentbelastningen. Sista steget var att utifrån resultaten ta fram en beräkningsmodell för lastfallet.</p><p>FE-modellen som skapades för testerna visade sig ge bärförmågor ca 10% under bärförmågan från de fysiska försöken. Detta berodde mycket på att balken var känslig för hur initialimperfektionerna såg ut och att första bucklingsmodens form användes vid modelleringen av de geometriska imperfektionerna.</p><p>Beräkningsmodellen utvecklades så att den skulle efterlikna den som gäller för lokal intryckning från vertikal last i EN 1993-1-5. Detta för att modellen skulle kunna användas som ett tillägg till EK3. Modellen utvecklades i tre delar, flytbärförmågan, kritiska bucklingslasten och reduktionsfaktorn för buckling. Modellen för flytbärförmågan togs fram analytiskt och fick en form som efterliknar den i EK3. Beräkningsmetoden för den kritiska bucklingslasten använder sig i princip av formlerna i EK3 förutom två små ändringar. Reduktionsfunktionen som valdes är en liten ökning av funktionen i EK3 men resultaten ligger ändå med bra marginal på säkra sidan. Den kompletta beräkningsmodellen ger resultat där säkerhetsmarginalen ökar vid minskande längd på lastöglan. Den har utformats så att den är lätt att använda och vid jämförelse med FE-försök gav beräkningsmodellen resultat på säkra sidan för alla balkar förutom några få av balkarna med låg slankhet. </p>
65

A local error analysis of the boundary concentrated FEM

Eibner, Tino, Melenk, Jens Markus 01 September 2006 (has links) (PDF)
The boundary concentrated finite element method is a variant of the hp-version of the FEM that is particularly suited for the numerical treatment of elliptic boundary value problems with smooth coefficients and boundary conditions with low regularity or non-smooth geometries. In this paper we consider the case of the discretization of a Dirichlet problem with exact solution $u \in H^{1+\delta}(\Omega)$ and investigate the local error in various norms. We show that for a $\beta > 0$ these norms behave as $O(N^{−\delta−\beta})$, where $N$ denotes the dimension of the underlying finite element space. Furthermore, we present a new Gauss-Lobatto based interpolation operator that is adapted to the case non-uniform polynomial degree distributions.
66

Colloidal Behaviour of Casein Micelles with Concentration

Krishnankutty Nair, Pulari 14 September 2012 (has links)
Structure function changes of casein micelles were studied as a function of concentration using a non invasive concentration method, osmotic stressing. A combination of serum analysis, light scattering and rheological measurements were used to characterize the physico-chemical properties of casein micelles. In heated and unheated milk, rheological studies indicated that casein micelles behave as hard spheres of similar volume fractions, if the viscosity changes in the serum phase and the particle particle interactions are taken into account. The differences in the distribution of the heat induced complexes between colloidal and soluble phase affected the colloidal properties of casein micelles. Above 70 g L-1 protein, the protein particles were no longer free diffusing. Re-dilution of the suspensions showed no irreversible aggregation. The data suggested that in the range of concentration studied casein micelles behave as hard spheres. Age gelation was also investigated on heated and unheated concentrated milk. In unheated concentrated milk proteolysis played an important role in imparting an increase in viscosity by causing aggregation of the casein micelles. On the other hand, in heated milk, there was a significant effect of the whey protein aggregates, which increased their interaction with the casein micelles over time. This effect, together with proteolysis caused age gelation in heated concentrated milk. The method of concentration used in this research, osmotic stressing, was then compared to ultrafiltration. It was demostrated that these two methods are not equivalent, as shear and mixing during ultrafiltration cause rearrangements to the casein micells. The differences were clearly demonstrated by adding soluble caseins to the milk before or after concentration. This project brings a better understanding on the effects of concentration on the structure-function of casein micelles and the interactions occurring in milk proteins during concentration.
67

Emissions From Concentrated Animal Feeding Operations During Wet and Dry Periods in the Southeastern United States

Winchester, Jesse N. F. 01 May 2015 (has links)
Air quality modeling is a recent development in atmospheric science dedicated to simulating the characteristics of surface emissions within the context of a variety of meteorological conditions. In western Kentucky, there are several concentrated animal feeding operations (CAFOs) that emit a variety of gases, including sulfur dioxide (SO2). The hypothesis was that the concentration and spread of SO2 emissions from these sources would differ between wet and dry periods over the CAFO locations. In this thesis, point emissions from locations representing CAFOs in western Kentucky and the transit of SO2throughout the southeastern U.S. were simulated in multiple sensitivity experiments using the Weather Research and Forecasting model with Chemistry (WRFChem). Simulations were performed for the convective precipitation events that occurred over western Kentucky between July 7 and July 13, 2012. The spatial coverage of SO2 emissions originating from the locations was reduced during precipitation events and expanded during dry periods. The average concentration of SO2 over the study area was also higher during the breaks between precipitation events than during times when precipitation was occurring. The highest concentrations of SO2 exceeding 1,000 pptv remained within close range of the emission locations for the majority of the simulations, except for when local surface winds were blowing at higher speeds. Most emissions from the locations remained limited to the surface and 850 mb levels.
68

Rheological Characterization Of Tahin/pekmez (sesame Paste/concentrated Grape Juice) Blends

Arslan, Elif 01 January 2004 (has links) (PDF)
The aim of this study was to determine the rheological properties of tahin/pekmez blends at different tahin concentrations (20-32%) and temperatures (35-65 &deg / C) by using a concentric cylinder rotational viscometer. Samples were sheared with seven different rotational speeds at an increasing order. The shear rates (0.75-63.9 s-1) were calculated by the Power-law Approximation method. Tahin/pekmez blends were found to exhibit non-Newtonian, shear thinning behavior at all temperatures and tahin concentrations. The experimental data of apparent viscosity versus shear rate were successfully described by the Power-law model. The model parameters / flow behavior index, n varied in the range of 0.7-0.85, whereas the values for the consistency coefficient, K, were in the range of 282-2547 mPa.sn. Apparent viscosity and consistency coefficient of blends increased with increasing tahin concentration and decreasing temperature. Temperature dependency of K was described by an Arrhenius-type equation. Activation energies (Ea) of the blends appeared in the range of 13376-28592 J/mol as the tahin concentration was increased from 20% to 32%. The effect of temperature on n was found to be significant but did not follow any descriptive trend. The relationship between K and tahin concentration was explained by exponential and power functions while tahin concentration had no significant effect on flow behavior index. Power function was found to be superior in explaining the variation of Ea with tahin concentration. A mathematical model was formulated to determine the combined effect of temperature, tahin concentration and shear rate on apparent viscosity.
69

Detection and isolation of thermophilic acidophilic bacteria from fuit juices

Duvenage, Wineen 03 1900 (has links)
Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2006. / Fruit juices were until recently considered to only be susceptible to spoilage by yeasts, mycelial fungi and lactic acid bacteria. Spoilage by these organisms was prevented by the acidic pH of fruit juices and the heat-treatment applied during the hot-fill-hold process. Despite these control measures, an increasing number of spoilage cases of fruit juices, fruit juice products and acidic vegetables due to contamination by thermophilic acidophilic bacteria (TAB) have been reported. The genus Alicyclobacillus, containing TAB were first classified as Bacillus, but were reclassified in 1992. Species of Alicyclobacillus are Gram-positive, rod-shaped, endospore-forming bacteria. The unique characteristic of these organisms is the presence of ω-alicyclic fatty acids, such as ω-cyclohexane and ω-cycloheptane, as the major components of the cellular membrane. This organism has been shown to survive pasteurisation conditions of 95°C for 2 min and grows within a pH range of 2.5 to 6.0 and temperatures between 25° and 60°C. The genus currently consists of 11 species, with A. acidoterrestris, A. acidocaldarius and A. pomorum being the only species associated with the spoilage of fruit juices and fruit juice products. The aim of this study was to evaluate culture-dependent and culture-independent approaches for the detection and isolation of Alicyclobacillus spp. from pasteurised South African fruit juices and concentrates. The culture-dependent approach was evaluated by comparing five different growth media, for growth and recovery of A. acidoterrestris, A. acidocaldarius and A. pomorum at different incubation temperatures, from sterile saline solution (SSS) (0.85% (m/v) NaCl), diluted and undiluted fruit juice concentrates. The five media evaluated included potato dextrose agar (PDA), orange serum agar (OSA), K-agar, yeast extract (YSG)-agar and Bacillus acidocaldarius medium (BAM). The culture-independent approach was used to identify the micro-organisms present in fruit juices and concentrates from different South African manufacturers before and after pasteurisation, using polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) and DNA sequencing. Spread plates of PDA at pH 3.7 and incubation temperature of 50°C for 3 days was found to be the best isolation media for species of Alicyclobacillus from fruit juice and fruit juice concentrate. With the inclusion of a heat shock treatment at 80°C for 10 min the growth media of preference for spores of Alicyclobacillus from fruit juice concentrates was OSA at pH 5.5 and an incubation temperature of 50°C for 3 days. The culture-dependent approach could detect cells or endospores at a minimum concentration of 104 cfu.ml-1 in SSS and diluted fruit juices. PCR-based DGGE analysis was more sensitive and detected cells of Alicyclobacillus spp. from fruit juices and concentrates at a minimum concentration of 103 cfu.ml-1. Alicyclobacillus acidoterrestris was found to be present in South African apple juice, pear juice, white grape juice and aloe vera juice. White grape juice was also found to contain A. pomorum. Other organisms present in the orange, apple, mango and pear juices were two uncultured bacteria that were identified as members of the genus Bacillus, and one uncultured bacterium closely related to Alcaligenus faecalis. This study confirmed the presence of TAB in pasteurised South African fruit juices and concentrates and emphasises the need for the rapid and accurate detection of TAB in food products.
70

Avaliação sensorial e físico-química do suco de laranja proveniente das etapas do proessamento do suco concentrado e congelado

Machado, Talita Vieira [UNESP] 17 December 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-17Bitstream added on 2014-06-13T19:50:28Z : No. of bitstreams: 1 machado_tv_me_arafcf.pdf: 1444727 bytes, checksum: 17c3368b3a744fcea057101e3e3dc459 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O suco de laranja é um produto de grande importância para a economia nacional, tendo papel relevante na pauta de exportações brasileiras. Em torno de 80% da laranja produzida no Brasil é processada na forma de suco de laranja concentrado e congelado (frozen concentrated orange juice-FCOJ). Durante o processamento do suco, podem ocorrer alterações das características do suco influenciando sua aceitação pelo consumidor. Os objetivos desse trabalho foram reunir informações referentes às características da laranja e à produção, à exportação, ao consumo de FCOJ, às etapas do processamento, às alterações sensoriais e físico-químicas que podem ocorrer durante o processamento, e avaliar a aceitação sensorial e a estabilidade físico-química do suco de laranja proveniente das etapas do processamento do suco concentrado e congelado. Uma equipe de 101 julgadores avaliou a cor, a impressão global, o aroma, o sabor e a textura do suco das etapas de extração, de filtração, de concentração, de resfriamento e de mistura de duas coletas, processados no início e no final da safra de 2009 da laranja da variedade Pêra-Rio. A estabilidade físico-química do suco de laranja proveniente das etapas do processamento do suco concentrado e congelado também foi avaliada no decorrer da safra de 2009, em cinco coletas. Foram realizadas análises do teor de sólidos solúveis, da acidez total titulável, de açúcares redutores, de açúcares totais, de ácido ascórbico, além do ratio e pH nos sucos das etapas de extração, filtração, concentração, resfriamento e mistura. Os sucos das etapas de extração e de filtração foram os mais aceitos pelos julgadores em relação aos atributos impressão global, aroma e sabor, e apresentaram maior intenção de compra entre os termos “provavelmente compraria” e “certamente compraria”. O suco da etapa de mistura, apesar... / The orange juice is a great importance product to the Brazilian economy, having a relevant role in Brazilian exports. Around 80% of oranges produced in Brazil are processed in the form of frozen concentrated orange juice (FCOJ). During the juice processing can result changes of the juice characteristics, influencing consumer acceptance. The aim of this work was to gather information regarding of orange characteristics and its production, exports and consumption of FCOJ, the processing steps and changes in sensory and physical-chemical properties that may occur during processing and to evaluate the sensorial acceptance and physical-chemistry stability of the juice coming from different steps of the concentrate juice processing. A group of 101 judges evaluated the color, the overall impression, aroma, flavor and texture of the juice from the steps of extraction, filtration, concentration, cooling and blend of two collections, processed at the beginning and end of the crop of pêra-rio orange variety in 2009. The physical-chemistry stability of the juice coming from the steps of processing of the concentrated juice was also evaluated during the 2009 harvest, in five collections. Were analyzed the soluble solids content (SS), total titratable acidity (TTA), reducing sugars (RS), total sugars (TS), ascorbic acid (AA), besides the ratio and pH in the juices of extraction, filtration, concentration, cooling and blend steps. The juices of the extraction and filtration steps were the most accepted for the attributes of overall impression, aroma and flavor, and showed higher purchase intention between “probably would purchase” and “definitely would purchase”. The juice of the blend step, despite being added essences to provide better aroma and flavor, had an average accepting less than that of the juice of cooling and concentration steps, which was not added essences, in both collections... (Complete abstract click electronic access below)

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