39 resultados para Two-Phase Start-up Demonstration Test


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The purpose of this research is to profile the characteristics and entrepreneurial motivations of graduate entrepreneurs from black and minority ethnic (BME) communities. The authors found that: BME graduate entrepreneurs were diverse in terms of their characteristics: size, gender, ethnicity and when they started the business. Almost all interviewees had worked for someone before they started their business. The two most compelling motivations for start up were 'being your own boss', especially for Indians and Bangladeshis; and making more money (31%), in particular for African Caribbeans. Over half of interviewees started a business in a sector in which they had prior experience, knowledge or skills. Two thirds of interviewees obtained advice from family and friends, while just over a third had completed any kind of training or course. This study has provided an insight into characteristics and entrepreneurial motivations of BME graduate entrepreneurs. Though the results of this study are indicative, there is a compelling case for further research into this relatively unexplored group.

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The possible evaporation of lubricant in fluid film bearings has been investigated theoretically and by experiment using a radial flow hydrostatic bearing supplied with liquid refrigerant R114. Good correlation between measured and theoretical values was obtained using a bespoke computational fluid dynamic model in which the flow was assumed to be laminar and adiabatic. The effects of viscous dissipation and vapour generation within the fluid film are fully accounted for by applying a fourth order Runge-Kutta routine to satisfy the radial and filmwise transverse constraints of momentum, energy and mass conservation. The results indicate that the radial velocity profile remains parabolic while the flow remains in the liquid phase and that the radial rate of enthalpy generation is then constant across the film at a given radius. The results also show that evaporation will commence at a radial location determined by geometry and flow conditions and in fluid layers adjacent to the solid boundaries. Evaporation is shown to progress in the radial direction and the load carrying capacity of such a bearing is reduced significantly. Expressions for the viscosity of the liquid/vapour mixture found in the literature survey have not been tested against experimental data. A new formulation is proposed in which the suitable choice of a characteristic constant yields close representation to any of these expressions. Operating constraints imposed by the design of the experimental apparatus limited the extent of the surface over which evaporation could be obtained, and prevented clear identification of the most suitable relationship for the viscosity of the liquid/vapour mixture. The theoretical model was extended to examine the development of two phase flow in a rotating shaft face seal of uniform thickness. Previous theoretical analyses have been based on the assumption that the radial velocity profile of the flow is always parabolic, and that the tangential component of velocity varies linearly from the value at the rotating surface, to zero at the stationary surface. The computational fluid dynamic analysis shows that viscous shear and dissipation in the fluid adjacent to the rotating surface leads to developing evaporation with a consequent reduction in tangential shear forces. The tangential velocity profile is predicted to decay rapidly through the film, exhibiting a profile entirely different to that assumed by previous investigators. Progressive evaporation takes place close to the moving wall and does not occur completely at a single radial location, as has been claimed in earlier work.

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Objectives The creation of more high-growth firms continues to be a key component of enterprise policy throughout the countries of the OECD. In the UK the developing enterprise policy framework highlights the importance of supporting businesses with growth potential. The difficulty, of course, is the ability of those delivering business support policies to accurately identify those businesses, especially at start-up, which will benefit from interventions and experiences an enhanced growth performance. This paper has a core objective of presenting new data on the number of high growth firms in the UK and providing an assessment of their economic significance. Approach This paper uses a specially created longitudinal firm-level database based on the Inter-Departmental Business Register (IDBR) held by the Office of National Statistics (ONS) for all private sector businesses in the UK for the period 1997-2008 to investigate the share of high-growth firms (including a sub-set of start-up more commonly referred to as gazelles) in successive cohorts of start-ups. We apply OECD definitions of high growth and gazelles to this database and are able to quantify for the first time their number (disaggregated by sector, region, size) and importance (employment and sales). Prior Work However, what is lacking at the core of this policy focus is any comprehensive statistical analysis of the scale and nature of high-growth firms in cohorts of new and established businesses. The evidence base in response to the question “Why do high-growth firms matter?” is surprisingly weak. Important work in this area has been initiated by Bartelsman et al., (2003),Hoffman and Jünge (2006) and Henreksen and Johansson (2009) but to date work in the UK has been limited (BERR, 2008b). Results We report that there are ~11,500 high growth firms in the UK in both 2005 and 2008. The share of high growth start-ups in the UK in 2005 (6.3%) was, contrary to the widely held perception in policy circles, higher than in the United States (5.2%). Of particular interest in the analysis are the growth trajectories (pattern of growth) of these firms as well as the extent to which they are restricted to technology-based or knowledge-based sectors. Implications and Value Using hitherto unused population data for the first time we have answered a fundamental research and policy question on the number and scale of high growth firms in the UK. We draw the conclusion that this ‘rare’ event does not readily lend itself to policy intervention on the grounds that the significant effort needed to identify such businesses ex ante would appear unjustified even if it was possible.

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The simulation of two-phase flow for an experimental airlift reactor (32-l volume) using commercially available software from Fluent Incorporated is presented here (http://www.fluent.co.uk). Data from the simulation is compared with the experimental data obtained by the tracking of a magnetic particle and analysis of the pressure drop to determine the gas hold-up. Comparisons between vertical velocity and gas hold-up were made for a series of experiments where the superficial gas velocity in the riser was adjusted between 0.01 and 0.075 m s-1. © 2003 Elsevier B.V. All rights reserved.

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Mixing phenomena observed when the flow rate in a single loop of the primary circuit is changed can influence the operation of pressurized water reactor (PWR) by inducing local gradients of boron concentration or coolant temperature. Analysis of one-dimensional Laser Doppler Anemometry (LDA) measurements during the start-up and shutdown of pump on a single loop of the ROCOM test facility has been performed. The effect of a step change and a ramped change in the flow rate on the axial and azimuthal velocities was examined. Numerical simulations were also performed for the step change in the flow rate that gave quantitative agreement with the axial velocities. Phenomenological agreement was made on the turbulent kinetic energy; however, observed values were a factor of 2.5 less than the turbulent kinetic energy derived from the measurements. © 2007.

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Objective: The purpose of this study was to determine the extent to which mobility indices (such as walking speed and postural sway), motor initiation, and cognitive function, specifically executive functions, including spatial planning, visual attention, and within participant variability, differentially predicted collisions in the near and far sides of the road with increasing age. Methods: Adults aged over 45 years participated in cognitive tests measuring executive function and visual attention (using Useful Field of View; UFoV®), mobility assessments (walking speed, sit-to-stand, self-reported mobility, and postural sway assessed using motion capture cameras), and gave road crossing choices in a two-way filmed real traffic pedestrian simulation. Results: A stepwise regression model of walking speed, start-up delay variability, and processing speed) explained 49.4% of the variance in near-side crossing errors. Walking speed, start-up delay measures (average & variability), and spatial planning explained 54.8% of the variance in far-side unsafe crossing errors. Start-up delay was predicted by walking speed only (explained 30.5%). Conclusion: Walking speed and start-up delay measures were consistent predictors of unsafe crossing behaviours. Cognitive measures, however, differentially predicted near-side errors (processing speed), and far-side errors (spatial planning). These findings offer potential contributions for identifying and rehabilitating at-risk older pedestrians.

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Despite the importance of new firms to the economy, determinants of start-ups have mainly been examined at a country level and discussion of regional entrepreneurial activity has received less attention. Since there are significant variations in entrepreneurship rates across and within countries, such an investigation at a regional level would help in gaining an in depth understanding of the impact of the individual level resource endowments and neighbourhood characteristics on an individual’s decision to engage in entrepreneurial activity. The main aim of the thesis is to explore various theories of entrepreneurship and develop integrated frameworks for examining the determinants of entrepreneurial activity at a neighbourhood level in the East Midlands region in England. The specific objectives of the thesis are to examine how the individual level resources and the neighbourhood characteristics: (i) combine to influence an individual to engage in the different stages of the entrepreneurial process, (ii) influence natives and migrants to engage in start up activity and (iii) influence women and men to become self-employed and ambitious entrepreneurs. In terms of the methodology, the empirical analysis is based on two databases combined: 2006 to 2009 GEM East Midlands region and the English Index of Multiple Deprivation dataset. Based on the critical review of the literature on entrepreneurship the thesis develop theoretical frameworks which led to formulate hypotheses related to the differentiated impact of both individual and neighbourhood level factors on the propensity of an individual to be involved in entrepreneurial activity. The findings indicate that the determinants of entrepreneurial activity vary with human, financial and the local environment factors affecting the entrepreneurial process. Finally, the thesis calls for caution when developing and applying generic and specific policy measures aimed at promoting entry into entrepreneurship.

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The present research represents a coherent approach to understanding the root causes of ethnic group differences in ability test performance. Two studies were conducted, each of which was designed to address a key knowledge gap in the ethnic bias literature. In Study 1, both the LR Method of Differential Item Functioning (DIF) detection and Mixture Latent Variable Modelling were used to investigate the degree to which Differential Test Functioning (DTF) could explain ethnic group test performance differences in a large, previously unpublished dataset. Though mean test score differences were observed between a number of ethnic groups, neither technique was able to identify ethnic DTF. This calls into question the practical application of DTF to understanding these group differences. Study 2 investigated whether a number of non-cognitive factors might explain ethnic group test performance differences on a variety of ability tests. Two factors – test familiarity and trait optimism – were able to explain a large proportion of ethnic group test score differences. Furthermore, test familiarity was found to mediate the relationship between socio-economic factors – particularly participant educational level and familial social status – and test performance, suggesting that test familiarity develops over time through the mechanism of exposure to ability testing in other contexts. These findings represent a substantial contribution to the field’s understanding of two key issues surrounding ethnic test performance differences. The author calls for a new line of research into these performance facilitating and debilitating factors, before recommendations are offered for practitioners to ensure fairer deployment of ability testing in high-stakes selection processes.

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The existence of adequate financial capital at start-up as well as during the lifetime of a firm is considered to be vital not only for its survival but also for its effective trading and growth, as it can act as a buffer against unforeseen difficulties (Cooper, Gimeno-Gascon, & Woo, 1994; Chandler & Hanks, 1998; Venkataraman & Van de Ven, 1998; Cassar, 2004). Inadequate or inappropriate capital structure is often the most common reason for a large proportion of small business failures (Chaganti, DeCarolis, & Deeds, 1995).