994 resultados para VVER-440 reactors
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Tavoitteeni tässä tutkimuksessa oli selvittää, miten kirjallisuustieteellisiä proosa-anayysin käsitteitä opetetaan opetussuunnitelman mukaisissa lukion äidinkielen ja kirjallisuuden oppikirjoissa ja miten hyvin kokelaat hallitsivat kertoja-käsitteen tekstitaidon ylioppilaskokeessa keväällä 2007. Samalla pohdin, minkälainen kirjallisuustieteellinen käsitteistö palvelisi tekstianalyysin opetusta koulussa, koska Lukion opetussuunnitelman perusteet 2003 ja äidinkielen ylioppilaskoe edellyttävät äidinkielen ja kirjallisuuden opetukselta ja oppilailta käsitteiden käyttöä. Tutkimusaineistonani olivat kaikki kuusi käytössä olevaa lukion äidinkielen ja kirjallisuuden oppikirjaa ja 440 kpl kevään 2007 äidinkielen tekstitaidon ylioppilaskokeen vastaustekstiä. Oppikirjoja tarkastelin soveltamalla niiden arviointiin Lev S. Vygotskin ajatuksia arkikäsitteiden ja tieteellisten käsitteiden opettamisesta ja Hans Aeblin esittämiä teoreettisia malleja käsitteiden opettamisesta ja oppimisesta. Tutkimukseni osoittaa, että opetussuunnitelmassa mainittujen proosa-analyysin käsitteiden kertoja, näkökulma, motiivi, aihe ja teema opetus on epätäsmällistä. Oppikirjoissa ei ole otettu huomioon sitä, että käsitteenoppiminen on monivaiheinen prosessi. Myöskään problematiikkaa, joka aiheutuu kyseisten käsitteiden määrittelyn kirjavuudesta ja käytöstä sekä arkikielen käsitteinä että tieteellisinä käsitteinä, ei oppikirjoissa käsitellä. Sama näkyy ylioppilaskoeaineistossa: oppilaat eivät hallitse käsitettä kertoja tieteellisenä käsitteenä. Tietoisuus kirjallisuustieteellisten käsitteiden määrittelyn problematiikasta ja arkikäsitteiden ja tieteellisten käsitteiden ontologisista kategorioista on onnistuneen käsitteenoppimisen edellytys. Kirjallisuustieteelliset käsitteet ovat metakäsitteitä, jotka edellyttävät oppilaiden metakäsitteellisen tietoisuuden ja motivaation hyödyntämistä opetuksessa, jossa olisi sovellettava monipuolisesti eri oppimiskäsitysten parhaita puolia hyödyntäviä lähestymistapoja, erilaisia pedagogisia diskursseja. Koulujen kirjallisuudenopetusta suunniteltaessa ja kirjallisuustieteellisiä käsitteitä opetettaessa on otettava huomioon niin kirjallisuustieteen kuin kasvatustieteen näkökulma. Opetussuunnitelman ja ylioppilaskokeen asettama vaatimus käsitteiden käytöstä on kohtuuton, mikäli ei sovita, miten käsitteet määritellään ja mitä käsitteitä kokelaiden oletetaan ylioppilaskokeessa hallitsevan. Kirjallisuustieteellisten käsitteiden puutteellisen opetuksen oppikirjoissa ja niiden epämääräisen käytön ylioppilaskokeen tehtävänannoissa ja arvioinnissa voi kärjistyneimmillään nähdä oppilaan oikeusturvakysymyksenä
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Although the production of liquid fuels from coal, natural gas (CTL and GTL processes) and other carbon sources has been discovered 90 years ago, the interest was renewed in the last years motivated by stranded gas reserves and by petroleum market instability. This review intends to show the scenario of these technologies nowadays, discussing the applied technologies, the steps in an industrial plant, the ways to produce syngas and liquid fuels, the catalysts used, the type of reactors and the operating plants with their respective capacities, besides the technical, economical and environmental viability, challenges and perspectives for Brazil.
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A didactic experiment is proposed aimed to extend the Flow Injection Analysis (FIA) based methodology to the area of physical chemistry/chemical reactors for undergraduate labs. Our prime objective was to describe the use of a gradient chamber for determination of the rate constant for the reaction between crystal violet and the hydroxide ion. The study was complemented by determining the effect of temperature on the rate constant. The kinetic parameters, activation energy and reaction rate constant are determined based on an assumption of rate orders. The main didactic advantages of the proposed experimental set-up are the use of less reagents, contributing to a more environmental friendly experiment. The experiment illustrates also the reduction of associated errors and time by using automated analysis owing to decreased operator manipulation.
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The immobilization of laccase on chitosan by cross-linking and application of the immobilized laccase in the bioconversion of phenolic compounds in batch and fixed bed reactors were studied. The process for immobilization of enzyme was optimized using a rotational central composite design. The optimized conditions to generate immobilized laccase with maximal activity were determined to be a glutaraldehyde concentration of 1.0% (v/v), a pH of 6.0, an immobilization time of 5.0 hours and an enzyme concentration of 5.2 g L-1. In packed bed reactors, the activity of the immobilized enzyme is maintained for a longer time in the bioconversion of 2,6-dimethoxyphenol than in the bioconversion of syringaldazine.
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Catalytic steam reforming of ethanol (SRE) is a promising route for the production of renewable hydrogen (H2). This article reviews the influence of doping supported-catalysts used in SRE on the conversion of ethanol, selectivity for H2, and stability during long reaction periods. In addition, promising new technologies such as membrane reactors and electrochemical reforming for performing SRE are presented.
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Nanoemulsions composed of a medium-chain triglyceride oil core stabilized by rapeseed or sunflower lecithins were prepared by spontaneous emulsification and high-pressure homogenization. These nanoemulsions are compared with formulations stabilized by egg lecithin. Nanoemulsions obtained by high-pressure homogenization display larger droplet size (230 to 440 nm) compared with those obtained by spontaneous emulsification (190 to 310 nm). The zeta potentials of the emulsions were negative and below -25 mV. Zeta potential inversion occurred between pH 3.0 and 4.0. The results demonstrate the feasibility of preparing lipid emulsions comprising rapeseed or sunflower lecithins by spontaneous emulsification and high-pressure homogenization.
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This article describes the development of a new catalytic reactor designed to operate with nanoparticle-embedded polymer thin films. Stabilization of metal nanoparticles in films that serve as catalysts in organic reactions is relatively new; therefore, the development of reactors to facilitate their use is necessary. We describe in detail the preparation of the GDCR reactor-type "dip catalyst" and its evaluation in the Suzuki - Miyaura cross-coupling reaction of phenylboronic acid and 4-bromoanisole catalyzed by palladium nanoparticle-embedded cellulose acetate thin film (CA/PD(0)). Compared with earlier prototypes, GDCR reactor showed excellent results when operating with CA/PD(0) thin films.
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The mild anodization (MA) reactor is exemplified for its operational simplicity and its excellent control over the experimental parameters that are involved in the anodization process. This method provides porous anodic alumina films with a regular cell-arrangement structure. This offers a better cost-benefit ratio than the other equipment configurations that are used to fabricate nanoporous structures (i.e., ion beam lithography). Conversely, the hard anodization (HA) reactor produces oxides at a rate that is 25 to 35 times faster than the MA reactor. The produced oxides also have greater layer thicknesses and interpore distance, and with a uniform nanopore spatial order (> 1000). In contrast to MA reactors, the construction of an HA reactor requires special components to maintain anodisation at a high potential regime. Herein, we describe and compare both reactors from a technical viewpoint.
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Soitinnus: piano.
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Airlift reactors are pneumatically agitated reactors that have been widely used in chemical, petrochemical, and bioprocess industries, such as fermentation and wastewater treatment. Computational Fluid Dynamics (CFD) has become more popular approach for design, scale-up and performance evaluation of such reactors. In the present work numerical simulations for internal-loop airlift reactors were performed using the transient Eulerian model with CFD package, ANSYS Fluent 12.1. The turbulence in the liquid phase is described using κ- ε the model. Global hydrodynamic parameters like gas holdup, gas velocity and liquid velocity have been investigated for a range of superficial gas velocities, both with 2D and 3D simulations. Moreover, the study of geometry and scale influence on the reactor have been considered. The results suggest that both, geometry and scale have significant effects on the hydrodynamic parameters, which may have substantial effects on the reactor performance. Grid refinement and time-step size effect have been discussed. Numerical calculations with gas-liquid-solid three-phase flow system have been carried out to investigate the effect of solid loading, solid particle size and solid density on the hydrodynamic characteristics of internal loop airlift reactor with different superficial gas velocities. It was observed that averaged gas holdup is significantly decreased with increasing slurry concentration. Simulations show that the riser gas holdup decreases with increase in solid particle diameter. In addition, it was found that the averaged solid holdup increases in the riser section with the increase of solid density. These produced results reveal that CFD have excellent potential to simulate two-phase and three-phase flow system.
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Chemical looping combustion (CLC) provides a promising technology to help cut carbon dioxide emissions. CLC is based on separated oxidation and reduction processes. Oxygen carrier, which is made from metal and supporting material, is in continuous recirculation between the air and fuel reactors. The CLC process does not require separation unit for carbon dioxide. The fuel reactor can produce an almost pure carbon dioxide feed which decrease costs of carbon capture and storage (CCS). The CLC method is one of the most promising ones for energy efficient carbon capture. A large amount of literature was examined for this study and from it the most promising methods and designs were chosen. These methods and designs were combined as reactor system design which was then sized during the making of this thesis. Sizing was done with a mathematical model that was further improved during the study.
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Tässä kirjallisuustyössä tutustutaan kolmeen kaupallisissa painevesilaitoksissa käytettyyn höyrystinkonstruktioon: U-putkipystyhöyrystimeen, U-putkivaakahöyrystimeen ja läpivirtaushöyrystimeen. Työssä tutustutaan näiden ratkaisujen erityispiirteisiin ja vertaillaan niitä keskenään.
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A mancha-alvo, causada pelo fungo Corynespora cassiicola, é a principal doença da parte área do tomateiro na região Norte do Brasil. No Estado do Amazonas o patógeno em plantas de pepino, causa severos danos à produção tanto em cultivo protegido quanto em campo aberto. O objetivo deste trabalho foi avaliar a reação de dez genótipos de pepino a C. cassiicola. O experimento foi conduzido em casa de vegetação em delineamento inteiramente ao acaso com dez tratamentos e dez repetições. Foram avaliados a cultivar Aodai e os híbridos tipo japonês General Lee F1, Hokushim, Japonês Híbrido F1 (Soudai), Jóia, Marketmore 76 (verde comprido), Natsubayashi, Natsu Suzumi, Sprint 440 II e Tsuyataro. Os isolados do patógeno foram obtidos a partir de folhas de plantas de pepino naturalmente infectadas, e multiplicado em meio de cultura BDA. As plantas foram inoculadas nas duas primeiras folhas definitivas com suspensão de inóculo na concentração 104 conídios mL-1 e mantidas em câmara úmida por 48 horas. A severidade foi avaliada e calculada a área abaixo da curva de progresso da doença (AACPD) para cada tratamento. Houve variação na reação dos genótipos ao patógeno e a cultivar Aodai apresentou menor AACPD considerada como resistente. Os híbridos Hokuchim, Soudai, Verde Comprido e Natsubayashi apresentaram menores valores de AACPD entre os híbridos avaliados em contraposição ao Tsuyataro o mais suscetível.
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Bound in: Dissertatio historica de paroecia Alandiae Lemland, eique annexa Lumparland / Daniel Ferdinandus Mallén. Aboae : typis Frenckellianis, [1792]
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O objetivo deste trabalho foi comparar três diferentes intervalos de tempo para difusão do bórax, visando a preservação de lâminas de sumaúma. O tratamento foi a aplicação por aspersão de 30 ml de solução, a 4% de concentração de bórax. Na pesquisa, optou-se pela retenção de 0,500% de equivalente de ácido bórico (EAB), com base na massa das lâminas secas. Avaliou-se a retenção nos tempos de difusão de 15, 150 e 270 minutos. Por meio da análise química quantitativa, foram verificados os níveis de retenção por espectrofotometria, obtendo-se 0,462, 0,457 e 0,440% de EAB, respectivamente, para os tratamentos de 15, 150 e 270 minutos, que não diferiram estatisticamente entre si pelo teste Tukey (p<0,05). Os resultados indicam uma boa difusão do bórax aos 15 minutos, o que demonstrou ser uma alternativa como tratamento preservante de madeira.