995 resultados para Economic flows


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The focus in this thesis is to study both technical and economical possibilities of novel on-line condition monitoring techniques in underground low voltage distribution cable networks. This thesis consists of literature study about fault progression mechanisms in modern low voltage cables, laboratory measurements to determine the base and restrictions of novel on-line condition monitoring methods, and economic evaluation, based on fault statistics and information gathered from Finnish distribution system operators. This thesis is closely related to master’s thesis “Channel Estimation and On-line Diagnosis of LV Distribution Cabling”, which focuses more on the actual condition monitoring methods and signal theory behind them.

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Allergic diseases including food allergy and eczema in an infant in combination with the everyday activities of caring for a family will pose challenges to parents. Only fragments of these challenges are revealed to health care professionals. Families have varying mental, social and economic resources to help them care for an allergic infant, and all such resources are important in determining how families succeed in meeting these challenges and the quality of the infant’s care. This study evaluated the whole burden to the family caused by an infant's allergic disease during the first 24 months of life. As the primary caregiver during this period is usually the mother, her perspective was considered important. Ecocultural theory, which considers families as capable of modifying the positive and negative forces facing them, was taken as the frame of reference. Data were collected as part of an ongoing prospective mother-infant study, and the methods included severity scoring of atopic dermatitis, dietary records, health-related quality of life measurements and assessments of the use of health care services and medications for treating the infant’s eczema, food allergy and asthma. Interviews with mothers were analysed by deductive content analysis on the basis of ecocultural theory and the family empowerment model. The theme “Living an ordinary family life” guided the organization of family activities essential for treating the infant's food allergy and eczema. These activities were sources of both strain and support for the mothers, the allergy-related supporting factors being the mother’s own knowledge of the allergy, hopes for an improvement in the infant’s condition, social support and work. An infant’s food allergy at the age of one year caused considerable strain for the mother in cases where the introduction of new foods into the child’s diet was delayed. This delay was still causing the mother additional strain when the child was 24 months of age. The infants waking at night at the ages of 12 and 24 months because of itching related to eczema caused strain for the mothers. The infants’ health-related quality of life was impaired at ages of 6 and 12 months compared with healthy infants. The principal reasons for impairments were itching, scratching and sleep disturbances at 6 and 12 months and treatment difficulties at 6 months. Problems with getting to sleep were reported at all stages irrespective of eczema and were also present in healthy infants. The economic impact of the treatment of allergic diseases on families during the first 24 months was 131 EUR (2006 value) in cases of eczema and 525 EUR in cases of food allergy. From the societal perspective, the costs of food allergy were a median of 3183 EUR (range 628–11 560 EUR) and of eczema a median of 275 EUR (range 94–1306 EUR). These large variations in costs in food allergy and eczema indicate that disease varies greatly . In conclusion, food allergy and eczema cause extra activities and costs to families which arrange these disease-related activities in such a way that they support the leading family theme “Living an ordinary family life”. Health care professionals should consider this thematic character of family life and disease-related activities in order to ensure that new treatments are sustainable, meaningful and tailored to daily activities. In addition, those mothers who are experiencing difficulties with food allergic infants or infants with eczema should be recognized early and provided with individual encouragement and support from health clinics. In the light of the present results, early detection of symptoms and effective parental guidance can contribute to the well-being and health-related quality of life of the child and family.

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Broschure of Centre for Economic Development, Transport and the Environment.

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Broschure of The Centres for Economic Development, Transport and the Environment.

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Maritime transport moves around 6 billion tonnes of freight every year. The freight consists of liquid bulks (45%), dry bulks (23%) and general cargo (32%). Freight traffic and transports chains vary according to region, commodity and the origin and the destination of freight. In the European Union the ports sector handles over 90% of the trade with third countries. The share of intra-EU trade is approximately 30% of the total transportation and the number of passengers is over 200 million every year. The Baltic Sea has more than 50,000 vessels a year pass the Skaw at the northernmost tip of Denmark on their way into or out of the Baltic. Roughly 60% to 70% of these vessels are cargo vessels and 17% to 25% tankers. Ports and maritime transport play a crucial role in global commerce today. Today’s business environment is changing rapidly, and the constant changes create challenges for the transport industry and maritime traffic. Ports have to adapt to continuous changes in economic structures, logistics demands, and people’s travel and leisure patterns. In order to ensure the competitiveness of sea connections, the ports need to fully enhance multilateral cross-border understanding and cooperation. In this report the focus is on liner traffic between five ports in the Central Baltic Region: Stockholm, Tallinn, Helsinki Turku and Naantali. The report defines the drivers of the demand for cargo and passenger traffic and highlights the most important factors. The economic situation and foreign trade of each county are elaborated on with detailed information about the flows of traffic between the five ports. Based on expert interviews, the main characteristics of each port, including strengths and weaknesses, are presented. The report is based on primary and secondary data. Primary data was received through interviews and mail surveys. Secondary data was attained through a literature research, statistics, data given by the PENTA ports and webpages. The report is divided into two main parts: the drivers creating the demand for transport and the results of current cargo and passenger flows between PENTA ports.

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This thesis presents an approach for formulating and validating a space averaged drag model for coarse mesh simulations of gas-solid flows in fluidized beds using the two-fluid model. Proper modeling for fluid dynamics is central in understanding any industrial multiphase flow. The gas-solid flows in fluidized beds are heterogeneous and usually simulated with the Eulerian description of phases. Such a description requires the usage of fine meshes and small time steps for the proper prediction of its hydrodynamics. Such constraint on the mesh and time step size results in a large number of control volumes and long computational times which are unaffordable for simulations of large scale fluidized beds. If proper closure models are not included, coarse mesh simulations for fluidized beds do not give reasonable results. The coarse mesh simulation fails to resolve the mesoscale structures and results in uniform solids concentration profiles. For a circulating fluidized bed riser, such predicted profiles result in a higher drag force between the gas and solid phase and also overestimated solids mass flux at the outlet. Thus, there is a need to formulate the closure correlations which can accurately predict the hydrodynamics using coarse meshes. This thesis uses the space averaging modeling approach in the formulation of closure models for coarse mesh simulations of the gas-solid flow in fluidized beds using Geldart group B particles. In the analysis of formulating the closure correlation for space averaged drag model, the main parameters for the modeling were found to be the averaging size, solid volume fraction, and distance from the wall. The closure model for the gas-solid drag force was formulated and validated for coarse mesh simulations of the riser, which showed the verification of this modeling approach. Coarse mesh simulations using the corrected drag model resulted in lowered values of solids mass flux. Such an approach is a promising tool in the formulation of appropriate closure models which can be used in coarse mesh simulations of large scale fluidized beds.

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The rapid economic growth in China has resulted in environmental challenges ranging from air pollution to water-related issues. Thus supporting clean technology, or cleantech, that encompasses industries that focus on alternative energy, pollution and recycling, power supplies and conservation has become one of the focal points in the Chinese economic policy for the next decade. Simultaneously, the Finnish government has initiated programs to support the internationalisation of domestic cleantech companies in an attempt to spiral the industry into one of the pillars of Finnish economic growth. This study concentrates on the conjunction of these two themes and studies the challenges faced by Finnish cleantech SMEs in the Chinese market. Consequently, the study answers the following sub questions: 1. What human and financial resource-based challenges do Finnish cleantech SMEs face in the Chinese market and what are their solutions? 2. What knowledge-based challenges do Finnish cleantech SMEs face in the Chinese market and how can these difficulties be resolved? 3. What network-based challenges do Finnish cleantech SMEs face in the Chinese market, how do they relate to the resource- and knowledge-based challenges, and how can these difficulties be resolved? This qualitative study is conducted by analysing four semi structured interviews collected from four Finnish SMEs that operate in China. The findings of the study indicate that in human resources the most important challenges are related to the hiring and retaining of employees. In contrast to extant academic literature results distinguish salary and social status as the main solutions to this challenge. Regarding financial resources it is discovered that cleantech companies enjoy a benign business environment in China and benefit from the Chinese government’s support for cleantech industry. Challenges related to knowledge resources can be grouped into categories with the most interesting knowledge flows being the stream of local market knowledge into to the foreign parent company and the outward flow of manufacturing and business practice information into the target venture. The challenge related to the first flow is gathering relevant information and the main solutions are clustering at the foreign location and hiring knowledge prior to internationalisation. Regarding the second flow the main challenge is related to intellectual property rights and the most interesting solution is the purposeful transformation of explicit knowledge into tacit knowledge. Finally, it is discovered that networks, called guanxi in China, greatly affect the business processes. Within the guanxi system there is the concept of face which was found to affect employee propensity to stay as well as, as a novel academic result, employees’ knowledge sharing intention.

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Brucellosis is an important zoonosis of worldwide distribution. Reliable epidemiologic brucellosis data covering approximately 90% of the cattle population in Brazil have been recently published. Therefore, considering the scarcity of information regarding the economic impact of bovine brucellosis in Brazil, the goal of this study was to estimate economic impact of brucellosis on the Brazilian cattle industry. Several parameters including abortion and perinatal mortality rates, temporary infertility, replacement costs, mortality, veterinary costs, milk and meat losses were considered in the model. Bovine brucellosis in Brazil results in an estimated loss of R$ 420,12 or R$ 226,47 for each individual dairy or beef infected female above 24 months of age, respectively. The total estimated losses in Brazil attributed to bovine brucellosis were estimated to be approximately R$ 892 million (equivalent to about 448 million American dollars). Every 1% increase or decrease in prevalence is expected to increase or decrease the economic burden of brucellosis in approximately 155 million Reais.

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The economic importance of small and medium-sized enterprises (SMEs) and entrepreneurship has increased significantly in recent decades and entrepreneurial activity and SMEs are deemed vital to economic progress. Therefore, it is justifiable to study how small firms and entrepreneurs can enhance their performance and emergence in the turbulent economic environment. The concept of entrepreneurial orientation (EO) has recently attracted considerable attention in the field of entrepreneurship research. EO generally refers to a firm’s propensity to be innovative, to be proactive and to take risks. A majority of EO studies so far have found that adopting EO associated entrepreneurial behaviors will help firms to create or sustain a high level of performance. This dissertation explores the main drivers and performance implications of EO for SMEs in time of economic crisis. Hence the first objective of this dissertation is to examine the performance implications of EO and to test the role of EO on how firms are treated by the crisis at operative level. The second objective is to expand the prevailing understanding of determinants of EO by exploring the relationship between owner's work related values, attitudes, demographic characteristics, firm’s financial resources and EO. EO was found to be a significant and positive factor behind a firm’s long run growth. Hence it can be said that EO has positive implications for firm performance. But on the other hand, during a time of economic crisis the different dimensions of EO had both positive and negative effects on performance of SMEs. The performance implications varied across different stages of the crisis and were also dependent on what measure was used for measuring the performance. The main drivers of EO in SMEs were the personal work related values of the entrepreneur and his/her prior experience as an entrepreneur. The intrinsic work values related to interest, responsibility, challenge, self-development or intellectual stimulation and values related to status, power, achievement and recognition had a positive effect on the level of EO. On the other hand, extrinsic values related to high income, material possessions, benefits such as generous holidays, job security, and comfort through good working conditions decreased the level of EO

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This thesis presents a set of methods and models for estimation of iron and slag flows in the blast furnace hearth and taphole. The main focus was put on predicting taphole flow patterns and estimating the effects of various taphole conditions on the drainage behavior of the blast furnace hearth. All models were based on a general understanding of the typical tap cycle of an industrial blast furnace. Some of the models were evaluated on short-term process data from the reference furnace. A computational fluid dynamics (CFD) model was built and applied to simulate the complicated hearth flows and thus to predict the regions of the hearth exerted to erosion under various operating conditions. Key boundary variables of the CFD model were provided by a simplified drainage model based on the first principles. By examining the evolutions of liquid outflow rates measured from the furnace studied, the drainage model was improved to include the effects of taphole diameter and length. The estimated slag delays showed good agreement with the observed ones. The liquid flows in the taphole were further studied using two different models and the results of both models indicated that it is more likely that separated flow of iron and slag occurs in the taphole when the liquid outflow rates are comparable during tapping. The drainage process was simulated with an integrated model based on an overall balance analysis: The high in-furnace overpressure can compensate for the resistances induced by the liquid flows in the hearth and through the taphole. Finally, a recently developed multiphase CFD model including interfacial forces between immiscible liquids was developed and both the actual iron-slag system and a water-oil system in laboratory scale were simulated. The model was demonstrated to be a useful tool for simulating hearth flows for gaining understanding of the complex phenomena in the drainage of the blast furnace.

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This work presents a new law of the wall formulation for recirculating turbulent flows. An alternative expression for the internal length which can be applied in the separated region is also presented. The formulation is implemented in a numerical code which solves the k-epsilon model through a finite volume method. The theoretical results are compared with the experimental data of Vogel and Eaton (J. of Heat Transfer, Transactions of ASME, vol.107, pp. 922-929, 1985). The paper shows that the present formulation furnishes better results than the standard k-epsilon formulation.

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A non isotropic turbulence model is extended and applied to three dimensional stably stratified flows and dispersion calculations. The model is derived from the algebraic stress model (including wall proximity effects), but it retains the simplicity of the "eddy viscosity" concept of first order models. The "modified k-epsilon" is implemented in a three dimensional numerical code. Once the flow is resolved, the predicted velocity and turbulence fields are interpolated into a second grid and used to solve the concentration equation. To evaluate the model, various steady state numerical solutions are compared with small scale dispersion experiments which were conducted at the wind tunnel of Mitsubishi Heavy Industries, in Japan. Stably stratified flows and plume dispersion over three distinct idealized complex topographies (flat and hilly terrain) are studied. Vertical profiles of velocity and pollutant concentration are shown and discussed. Also, comparisons are made against the results obtained with the standard k-epsilon model.

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Fuel elements of PWR type nuclear reactors consist of rod bundles, arranged in a square array, and held by spacer grids. The coolant flows, mainly, axially along the rods. Although such elements are laterally open, experiments are performed in closed type test sections, originating the appearance of subchannels with different geometries. In the present work, utilizing a test section of two bundles of 4x4 pins each, experiments were performed to determine the friction and the grid drag coefficients for the different subchannels and to observe the effect of the grids in the crossflow, in cases of inlet flow maldistribution.