927 resultados para Two-Phase Start-up Demonstration Test


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The purpose of this thesis is to study how Russian entrepreneurs perceive Finnish institutional environment and innovation support policies provided in the country, as well as to present a practical example in form of a case study of one technology oriented start-up firm which was established in Finland by Russian entrepreneurs. The empirical research of the thesis is conducted qualitatively in two parts. First part is conducted through online questionnaire with open questions in order to review the perceptions of Russian entrepreneurs in general. Second part is based on personal interviews with case company’s founders with the focus on the process of establishing the company in Finland. In the first part of the empirical research, five Russian start-up firms were contacted, and four responses were received. All of these responses were qualified for further analysis. The findings of the first part of the research reveal that Russian entrepreneurs have rather positive attitudes towards Finnish institutional innovation support policies. However, most of the entrepreneurs stated that they are unlikely to create their presence in Finland. As an outcome of the second part of the research, the process of establishing a case company in Finland is illustrated. In order to be able to establish companies in Finland, Russian entrepreneurs who have a permanent residence outside European Economic Area (EEA) are required to apply for a permission to perform business operations in the country. In addition, the established company must engage in improving the economical stand of the country by creating new work places, raising tax revenues, develop technologies and generate innovations in the country.

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This paper presents an experimental research about the behavior of two-phase flows in inclined pipes. The inclination angle varied from 5° to 45° and the slurry solid concentration varied up to 15%. It was concluded that the head losses of the downward sloping pipe flow are always lower than the head losses of the horizontal flow and these are always lower than the head losses of the upward sloping pipe flow, regardless the concentration and inclination angle. It was possible to develop empirical equations to calculate the head losses of the horizontal flow and the upward and downward sloping pipe flows.

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Heat transfer effectiveness in nuclear rod bundles is of great importance to nuclear reactor safety and economics. An important design parameter is the Critical Heat Flux (CHF), which limits the transferred heat from the fuel to the coolant. The CHF is determined by flow behaviour, especially the turbulence created inside the fuel rod bundle. Adiabatic experiments can be used to characterize the flow behaviour separately from the heat transfer phenomena in diabatic flow. To enhance the turbulence, mixing vanes are attached to spacer grids, which hold the rods in place. The vanes either make the flow swirl around a single sub-channel or induce cross-mixing between adjacent sub-channels. In adiabatic two-phase conditions an important phenomenon that can be investigated is the effect of the spacer on canceling the lift force, which collects the small bubbles to the rod surfaces leading to decreased CHF in diabatic conditions and thus limits the reactor power. Computational Fluid Dynamics (CFD) can be used to simulate the flow numerically and to test how different spacer configurations affect the flow. Experimental data is needed to validate and verify the used CFD models. Especially the modeling of turbulence is challenging even for single-phase flow inside the complex sub-channel geometry. In two-phase flow other factors such as bubble dynamics further complicate the modeling. To investigate the spacer grid effect on two-phase flow, and to provide further experimental data for CFD validation, a series of experiments was run on an adiabatic sub-channel flow loop using a duct-type spacer grid with different configurations. Utilizing the wire-mesh sensor technology, the facility gives high resolution experimental data in both time and space. The experimental results indicate that the duct-type spacer grid is less effective in canceling the lift force effect than the egg-crate type spacer tested earlier.

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A two-phase anaerobic biodigestor was employed in order to analyze methane production with different manipueira organic loading rates. The acidogenic phase was carried out in a batch process whereas the methanogenic in an up-flow anaerobic fixed bed reactor with continuous feeding. The organic loading rates varied from 0.33 up to 8.48g of Chemical Demand Oxygen (COD)/L.day. The highest content of methane, 80.9%, was obtained with organic loading rate of 0.33g and the lowest, 56.8%, with 8.48gCOD/L.d. The highest reduction of COD, 88.89%, was obtained with organic loading rate of 2.25g and the lowest, 54.95%, with 8.48gCOD/L.d. From these data it was possible to realize that anaerobic biodigestion can be managed in at least two ways, i.e., for energy production (methane) or for organic loading reduction. The organic loading rate should be calculated as part of the purpose of the treatment to be accomplished.

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The role of star-up firms in economy and the importance of venture capital investors for the growth of start-up firms have been highlighted in recent years. The growth challenges of start-up firms consist of fast changing environment, the availability of venture capital funding and the development of firm management in the growth phase. A growing number of studies have focused on management accounting systems and venture capital in start-up and growth firm context. In this thesis the role of management accounting systems and venture capital investors is considered in the growth phase of firm development. The theoretical objective of this thesis is to construct a theoretical framework in order to describe the importance of management accounting systems and venture capital investors in start-up firms. The practice orientated objective of this thesis is to study the application of management accounting systems and management accounting based information in start-up firms in high-technology industry as well as the impact of venture capital for management accounting system design. In addition, the growth challenges of start-up firms are studied in order to understand the context in which management accounting systems are used. The research approach of theoretical part is conceptual as the theoretical framework is constructed by combining literature on firm growth, management accounting and venture finance in order to analyse the phenomenon. The action-orientated research approach is appropriate for analysing and describing of the studied phenomenon through empirical evidence. The empirical evidence was collected through interviews with three experts in start-up firm accelerator centers, four representatives of start-up firms and one venture capital investor. The results indicate that the growth challenges of stat-up firms are not related to the development of management accounting systems. Managers of start-up firms expressed a positive attitude towards management accounting systems that improve efficiency of operations. In start-up firms flexible and adjustable management accounting practices, such as budgets, cash flow calculations and future-orientated analysis tools, are applied that support planning and coordination of operations. The results indicate that venture capital investors affect the provision and the quality of management accounting information during the investment process. In addition, venture capital investors enhance the use of management accounting information for internal coordination in start-up firms. By applying the theoretical framework in the analysis, it can be stated that by acting as support function management accounting systems facilitate start-up firms development.

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Unit Commitment Problem (UCP) in power system refers to the problem of determining the on/ off status of generating units that minimize the operating cost during a given time horizon. Since various system and generation constraints are to be satisfied while finding the optimum schedule, UCP turns to be a constrained optimization problem in power system scheduling. Numerical solutions developed are limited for small systems and heuristic methodologies find difficulty in handling stochastic cost functions associated with practical systems. This paper models Unit Commitment as a multi stage decision making task and an efficient Reinforcement Learning solution is formulated considering minimum up time /down time constraints. The correctness and efficiency of the developed solutions are verified for standard test systems

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We present a variable time step, fully adaptive in space, hybrid method for the accurate simulation of incompressible two-phase flows in the presence of surface tension in two dimensions. The method is based on the hybrid level set/front-tracking approach proposed in [H. D. Ceniceros and A. M. Roma, J. Comput. Phys., 205, 391400, 2005]. Geometric, interfacial quantities are computed from front-tracking via the immersed-boundary setting while the signed distance (level set) function, which is evaluated fast and to machine precision, is used as a fluid indicator. The surface tension force is obtained by employing the mixed Eulerian/Lagrangian representation introduced in [S. Shin, S. I. Abdel-Khalik, V. Daru and D. Juric, J. Comput. Phys., 203, 493-516, 2005] whose success for greatly reducing parasitic currents has been demonstrated. The use of our accurate fluid indicator together with effective Lagrangian marker control enhance this parasitic current reduction by several orders of magnitude. To resolve accurately and efficiently sharp gradients and salient flow features we employ dynamic, adaptive mesh refinements. This spatial adaption is used in concert with a dynamic control of the distribution of the Lagrangian nodes along the fluid interface and a variable time step, linearly implicit time integration scheme. We present numerical examples designed to test the capabilities and performance of the proposed approach as well as three applications: the long-time evolution of a fluid interface undergoing Rayleigh-Taylor instability, an example of bubble ascending dynamics, and a drop impacting on a free interface whose dynamics we compare with both existing numerical and experimental data.

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We design and investigate a sequential discontinuous Galerkin method to approximate two-phase immiscible incompressible flows in heterogeneous porous media with discontinuous capillary pressures. The nonlinear interface conditions are enforced weakly through an adequate design of the penalties on interelement jumps of the pressure and the saturation. An accurate reconstruction of the total velocity is considered in the Raviart-Thomas(-Nedelec) finite element spaces, together with diffusivity-dependent weighted averages to cope with degeneracies in the saturation equation and with media heterogeneities. The proposed method is assessed on one-dimensional test cases exhibiting rough solutions, degeneracies, and capillary barriers. Stable and accurate solutions are obtained without limiters. (C) 2010 Elsevier B.V. All rights reserved.

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In this study, gaseous emissions and particles are measured during start-up and stop periods for an over-fed boiler and an under-fed boiler. Both gaseous and particulate matter emissions are continuously measured in the laboratory. The measurement of gaseous emissions includes oxygen (O2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxide and (NO). The emissions rates are calculated from measured emissions concentrations and flue gas flow. The behaviours of the boilers during start-up and stop periods are analysed and the emissions are characterised in terms of CO, NO, TOC and particles (PM2.5 mass and number). The duration of the characterised periods vary between two boilers due to the difference in type of ignition and combustion control. The under-fed boiler B produces higher emissions during start-up periods than the over-fed boiler A. More hydrocarbon and particles are emitted by the under-fed boiler during stop periods. Accumulated mass of CO and TOC during start-up and stop periods contribute a major portion of the total mass emitted during whole operation. However, accumulated mass of NO and PM during start-up and stop periods are not significant as the duration of emission peak is relatively short.

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The e-business market is one of the fastest growing markets in Brazil, with e-business sales accounting for BRL 14.8 billion in 2010 and a growth of 40% per year (+1000% over the past 7 years). Sales-event clubs and collective bargaining websites are one of the most dynamic segments of the e-business market: the number of new players is increasing rapidly, with over 1200 collective bargaining websites currently operating in Brazil. In that context, growth and differentiation seem to be two key success factors for Coquelux. According to webshopper (23rd Edition, e-bit), growth can be achieved by targeting middle and low-income consumers from class C, who represent 50% of the total e-commerce sales. But Coquelux, which is specialized in desire and luxury brands, has built its reputation and competitive advantage through its “exclusivity”, by targeting wealthier consumers from classes A and B who are attracted by its fashionable and high-end positioning. The evolution (growth?) of this market and the development of its competition naturally raise a strategic question for Coquelux’s managers: can Coquelux grow and still maintain its competitive advantage? Should it grow by expanding its consumer base to class C? If so, how? Consumers from classes A, B or C must be targeted through the same online communication channels. Recent studies from the ABEP/ABIPEME emphasized the importance of social networks as a tool for converting new clients and gaining their loyalty, regardless of their social class. However, high-income and low-income e-consumers do not have the same consumption habits, do not respond to the same type of marketing strategies, and most importantly, do not share the same values. Thus, it seems difficult to expand Coquelux’s consumer base to class C without changing its marketing strategies and altering its image Three options were identified for Coquelux: reinforcing its leadership on the luxury segment and focusing on a small niche market (1), which would threaten its survival in the long run; completely changing its strategy and competing for a mass market through commercial brands (2), which requires major financial investments that managers don’t have access to; or finding an intermediary solution (3). This thesis’ recommendation for the third option consists in focusing on premium brands (rather than luxury) in order to increase sales volume (Coquelux’s most profitable sales happened with local desire brands) with products that appeal to class B but also attract the emerging class C which is looking for brand recognition. It could thus implement a slow entry strategy towards the mass market without damaging its main competitive advantage.

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Em um esforço continuo de sobrevivência, corporações buscam meios para expandir seus negócios, seja dentro de seus mercados atuantes, ou na exploração de novos mercados. Para alcançar esse objetivo, inovações são realizadas pelos funcionários que, por meio de suas iniciativas, praticam o empreendedorismo coorporativo. São diversas formas em que o empreendedorismo corporativo se manifesta, dentre elas por meio de aquisições. Ao comprar uma outra empresa, a empresa compradora tem como motivação a busca de alguns atributos que complementem seus objetivos iniciais. Após a compra, o processo de integração entre as duas empresas é, por muitas vezes, complicado e penoso. O objetivo desse estudo é o de identificar quais são essas motivações de compra, os problemas enfrentados durante a integração entre as duas empresas, e quais são as lições aprendidas por grandes/médias corporações quando adquirem Start-ups. Muitos estudos atualmente tratam de temas relacionados à aquisição de empresas, porém, quando se trata de Start-ups, pouca literatura é encontrada. Os resultados dessa pesquisa são fruto de entrevistas com os gestores e empreendedores que participaram do processo de aquisição da SAMURAI pela Momentum e da Save-me pela Buscapé – empresas brasileiras. Os resultados são seis sugestões que devem ser consideradas por grandes/medias corporações antes e durante o processo de aquisição de uma strat-up: (i) A base de clientes da empresa comprada deve ser cuidadosamente considerada; (ii) um contato muito próximo entre os gestores das duas empresas é crucial antes da realização da aquisição; (iii) a contratação de uma empresa de consultoria em aquisições pode ser primordial durante o processo de integração; (iv) o empreendedor tem um papel de central importância para o future da nova empresa formada após a aquisição; (v) a forma como a integração entre as duas empresas ocorrerá após a compra deve ser cuidadosamente escolhida e (iv) a criação de uma corporate venture deve ser levada em consideração.

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The partitioning of Green Fluorescent Protein (GFP) in poly(ethylene glycol)/Na-poly(acrylate) aqueous two-phase systems (PEG/NaPA-ATPS) has been investigated. The aqueous two-phase systems are formed by mixing the polymers with a salt and a protein solution. The protein partitioning in the two-phase system was investigated at 25 degrees C. The concentration of the GFP was measured by fluorimetry. It was found that the partitioning of GFP depends on the salt type, pH and concentration of PEG. The data indicates that GFP partitions more strongly to the PEG phase in presence of Na2SO4 relative to NaCl. Furthermore, the GFP partitions more to the PEG phase at higher pH. The partition to the PEG phase is strongly favoured in systems with larger tie-line lengths (i.e. systems with higher polymer concentrations). The molecular weight of PEG is important since the partition coefficient (K) of GFP gradually decreases with increasing PEG size, from K ca. 300-400 for PEG 400 to K equal to 1.19 for PEG 8000. A separation process was developed where GFP was separated from a homogenate in two extraction steps: the GFP is first partitioned to the PEG phase in a PEG 3000/NaPA 8000 system containing 3 wt% Na2SO4, where the K value of GFP was 8. The GFP is then re-extracted to a salt phase formed by mixing the previous top-phase with a Na2SO4 solution. The K-value of GFP in this back-extraction was 0.22. The total recovery based on the start material was 74%. (c) 2008 Elsevier B.V. All rights reserved.

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Um biodigestor anaeróbio de duas fases foi utilizado para se analisar a produção de metano com diferentes cargas de entrada de manipueira. A fase acidogênica foi realizada em processo de batelada e a metanogênica em biodigestor anaeróbio de fluxo ascendente e leito fixo com alimentação contínua. As cargas orgânicas de entrada variaram de 0,33 a 8,48 gDQO (Demanda Química de Oxigênio)/L.dia. A maior porcentagem de metano encontrada foi de 80,9%, com carga orgânica de 0,33g e a menor, 56,8%, obtida com 8,49gDQO/L.d. A maior taxa de redução de DQO foi de 88,89%, obtida com carga orgânica de 2,25g e a menor, 54,95%, com 8,48gDQO/L.d. Analisando-se os dados apresentados verificou-se que a biodigestão anaeróbia pode ser conduzida, pelo menos, de duas maneiras, ou seja, para produção de energia (metano) ou para redução de carga orgânica. A carga orgânica de entrada deve ser calculada em função do objetivo a ser alcançado com a biodigestão anaeróbia.

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Um dos resíduos gerados no processamento da mandioca (Manihot esculenta) é a manipueira, passível de tratamento por biodigestão anaeróbia. Este trabalho objetivou estudar o processo de partida de um biodigestor tipo plug-flow, tratando manipueira de duas maneiras: diminuindo-se gradativamente o tempo de retenção hidráulica (TRH) até se chegar ao tempo pré-estabelecido, quatro dias; ou mantendo-se o TRH fixo em quatro dias e aumentando-se gradativamente a concentração do afluente. O biodigestor, com capacidade 1980 mL, foi mantido a temperatura de 32ºC ± 1. Empregou-se como substrato manipueira e ajustou-se o pH entre 5,5 e 6,0. A primeira etapa foi caracterizada empregando-se TRH de 16,6; 13,6; 11,6 e 9,6 dias e 3,1; 2,0; 2,3 e 2,9 g DQO L-1 d-1 de carga orgânica, respectivamente. Na segunda etapa manteve-se TRH fixo, 4 dias, porém cargas orgânicas de 0,48, 0,86, 1,65 e 2,46 g DQO L-1 d-1. Determinaram-se no afluente e efluente, sólidos totais (ST) e sólidos voláteis (SV), demanda química de oxigênio (DQO), alcalinidade e acidez volátil. Na primeira etapa, melhores resultados foram observados trabalhando com TRH 9,6 dias e carga orgânica 2,9 g DQO L-1 d-1, quando houve redução de DQO, ST e SV de 60%, 44% e 60%, respectivamente. Na segunda etapa o TRH de 4 dias apresentou melhores resultados empregando-se carga orgânica de 0,86 g DQO L-1 d-1, houve redução de 71%, 58% e 79% de DQO, ST e SV, respectivamente. A partida do biodigestor plug-flow tratando manipueira, pode ser realizada tanto diminuindo-se o TRH, quanto mantendo-o fixo e aumentado-se a concentração do afluente.

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This study evaluated the ethanol addition as a strategy for start-up and acclimation of a pilot scale (1300 L) anaerobic sequencing batch biofilm reactor (AnSBBR) for the treatment of municipal landfill leachate with seasonal biodegradability variations. The treatment was carried out at ambient temperature (23.8 ± 2.1 °C) in the landfill area. In a first attempt, the leachate collected directly from landfill showed to be predominantly recalcitrant to anaerobic treatment and the acclimation was not possible. In a second attempt, adding ethanol to leachate, the reactor was successfully acclimated. After acclimation, without ethanol addition, the CODTotal influent ranged from 4970 to 13040 mg L-1 and the removal efficiencies ranged from 12.1% to 70.7%. A final test was carried out increasing the ammonia and free-ammonia concentration from 2486 mgN L-1 and 184 mgN L-1 to 4519 mgN L-1 and 634 mgN L-1, respectively, with no expressive inhibition verified. The start-up strategy was found to be feasible, providing the acclimation of the biomass in the AnSBBR, and maintaining the biomass active even when the leachate was recalcitrant. © 2013 Elsevier Ltd. All rights reserved.