974 resultados para boundary work


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In this paper, the steady laminar viscous hypersonic flow of an electrically conducting fluid in the region of the stagnation point of an insulating blunt body in the presence of a radial magnetic field is studied by similarity solution approach, taking into account the variation of the product of density and viscosity across the boundary layer. The two coupled non-linear ordinary differential equations are solved simultaneously using Runge-Kutta-Gill method. It has been found that the effect of the variation of the product of density and viscosity on skin friction coefficient and Nusselt number is appreciable. The skin friction coefficient increases but Nusselt number decreases as the magnetic field or the total enthalpy at the wall increases

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A quartic profile in terms of the normal distance from the wall has been taken and coefficients are evaluated by satisfying one more boundary condition on the wall than the usual one. By doing so, the limitations about the Reynolds number of the quartic profile adopted by Lew (1949) has been removed. The Kármán (1921) Momentum Integral Equation has been used to evaluate the various characteristics of the flow. A comparative study of Lew's quartic profile and exponential profile together with the quartic profile of the present paper has been undertaken and the graphs for the various characteristics of the flow for a number of Mach numbers and suction coefficients have been drawn. At the end, certain conclusions of general nature about the velocity profiles have been recorded.

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In this paper we have discussed the boundary layer on a plate with suction. The problem is solved near the leading edge as well as far downstream. A linear suction law is assumed near the leading edge for simplicity, whereas no restriction is placed on the suction law in the region downstream. An explict expression for boundary layer thickness in terms of suction speed and distance from leading edge is derived. It is found that the thickness of the boundary layer depends on the derivative of the suction speed. The skin friction also has been evaluated. Though near the leading edge a linear law of suction is assumed, the method used in the paper can be easily generalised for any other power law, for example, we may use a power series expansion for the function defining the suction velocity.

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This article reports on a cross-sectional case study of a large construction project in which Electronic document management (EDM) was used. Attitudes towards EDM from the perspective of individual end users were investigated. Responses from a survey were combined with data from system usage log files to obtain an overview of attitudes prevalent in different user segments of the total population of 334 users. The survey was followed by semi-structured interviews with representative users. A strong majority of users from all segments of the project group considered EDM as a valuable aid in their work processes, despite certain functional limitations of the system used and the complexity of the information mass. Based on the study a model describing the key factors affecting end user EDM adoption is proposed. The model draws on insight from earlier studies of EDM enabled projects and theoretical frameworks on technology acceptance and success of information systems, as well as the insights gained from the case study.

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Aspects of large-scale organized structures in sink flow turbulent and reverse-transitional boundary layers are studied experimentally using hot-wire anemometry. Each of the present sink flow boundary layers is in a state of 'perfect equilibrium' or 'exact self-preservation' in the sense of Townsend (The Structure of Turbulent Shear Flow, 1st and 2nd edns, 1956, 1976, Cambridge University Press) and Rotta (Progr. Aeronaut. Sci., vol. 2, 1962, pp. 1-220) and conforms to the notion of 'pure wall-flow' (Coles, J. Aerosp. Sci., vol. 24, 1957, pp. 495-506), at least for the turbulent cases. It is found that the characteristic inclination angle of the structure undergoes a systematic decrease with the increase in strength of the streamwise favourable pressure gradient. Detectable wall-normal extent of the structure is found to be typically half of the boundary layer thickness. Streamwise extent of the structure shows marked increase as the favourable pressure gradient is made progressively severe. Proposals for the typical eddy forms in sink flow turbulent and reverse-transitional flows are presented, and the possibility of structural self-organization (i.e. individual hairpin vortices forming streamwise coherent hairpin packets) in these flows is also discussed. It is further indicated that these structural ideas may be used to explain, from a structural viewpoint, the phenomenon of soft relaminarization or reverse transition of turbulent boundary layers when subjected to strong streamwise favourable pressure gradients. Taylor's 'frozen turbulence' hypothesis is experimentally shown to be valid for flows in the present study even though large streamwise accelerations are involved, the flow being even reverse transitional in some cases. Possible conditions, which are required to be satisfied for the safe use of Taylor's hypothesis in pressure-gradient-driven flows, are also outlined. Measured convection velocities are found to be fairly close to the local mean velocities (typically 90% or more) suggesting that the structure gets convected downstream almost along with the mean flow.

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This paper summarizes literature explaining workplace bullying and focuses on organisational antecedents of bullying. In order to better understand the logic behind bullying, a model discussing different types of explanations is put forward. Thus, explanations for and factors associated with bullying are classified into three groups, i.e. enabling structures or necessary antecedents (e.g. perceived power imbalances, low perceived costs, and dissatisfaction and frustration), motivating structures or incentives (e.g. internal competition, reward systems, and expected benefits), and precipitating processes or triggering circumstances (e.g. downsizing and restructuring, organisational changes, changes in the composition of the workgroup). The paper concludes that bullying is often an interaction between structures and processes from all three groupings.

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This paper argues that workplace bullying can in some cases be a form of organisational politics, that is, a deliberate, competitive strategy from the perspective of the individual perpetrator. A cross-sectional study conducted among business professionals revealed that there was a correlation between a politicised and competitive climate and bullying. This finding implies that globalisation, increased pressures for efficiency, and restructuring, which limits the number of management positions and thereby contributes to increased internal competition, may lead to more bullying. The findings have important implications for management, since the possible political aspects of bullying must be taken into account in order to be able to undertake successful prevention and intervention measures.

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This study explores the relationship between Intellectual Capital and Maintenance of Work Ability. Intellectual Capital is the central framework for analysing the increasing knowledge-intensiveness of business life. It is characteristic of Intellectual Capital that the intersection of human capital, internal structures and external structures is essential. Maintenance of Work Ability, on the other hand, has been the leading paradigm for Finnish occupational health and safety activities since the late 1980s. It is also a holistic approach that emphasises the interdependence of competence, work community, work environment and health as the key to work-related wellbeing. This thesis consists of five essays that scrutinise the focal phenomena both theoretically and empirically. The conceptual model that results from the first research essay provides a general framework for the whole thesis. The case study in the second essay supports a division of intangible assets into generative and commercially exploitable intangibles introduced in the first essay and further into the primary and secondary dimension of generative intangibles. Further scrutiny of the interaction of generative intangible assets in essay three reveals that employees’ wellbeing enhances the readiness to contribute to the knowledge creation process. The fourth essay shows that the MWA framework could benefit knowledge-intensive work but this would require a different approach than has been commonly adopted in Finland. In essay five, deeper analysis of the MWA framework shows that its potential results from comprehensive support of the functioning of an organisation. The general conclusion of this thesis is that organisations must take care of their employees’ wellbeing in order to secure innovativeness that is the key to surviving in today’s competitive business environment.

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The successful interaction between leaders and their followers is central to the overall functioning of a company. The increasingly multinational nature of modern business and the resulting multicultural and increasingly heterogeneous workforce imposes specific challenges to the development of high-quality work relationships. The Western multinational companies that have started operations in China are facing these challenges. This study examines the quality of leader-follower relationships between Western expatriate leaders and their Chinese followers as well as between Chinese leaders and their Chinese followers in Western-owned subsidiaries in China. The focus is on the influence of personal, interpersonal and behavioural factors (personality, values, cultural knowledge, perceived and actual similarity, interactional justice, and follower performance) and the work-related implications of these relationships (job attitudes and organisational citizenship behaviour). One interesting finding of this study is that Chinese followers have higher perceptions of their Western than their Chinese leaders. The results also indicate that Chinese and Western leaders’ perceptions of their followers are not influenced favourably by the same follower characteristics. In a similar vein, Chinese followers value different traits in Western versus Chinese leaders. These results, as well as the numerous more specific findings of the study, have practical implications for international human resource management and areas such as selection, placement and training. Due to the different effect of personal and interpersonal factors across groups, it is difficult to achieve the “perfect match” between leader and follower characteristics that simultaneously contribute to high-quality relationships for Chinese and Western leaders as well as for followers. However, the results indicate that the ability of organisations to enhance the quality of leader-follower relations by selecting and matching people with suitable characteristics may provide an effective means for organisations to increase positive job attitudes and hence influence work-related outcomes.