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Search Results: 1 - 10 of 904 matches for " Urban "
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Optimization of the Tilted Fibre Bragg Gratings for the Fibre Accelerometric Sensor  [PDF]
Frantisek Urban
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.27006

The presentation shows the principle and construction of the fibre optic accelerometric sensor. The sensor element is based on the use of the tilted fibre Bragg grating (TFBG) that is imprinted to the bend insensitive single-mode telecommunication grade fibre. The fibre section with TFBG is then coupled to the evaluation fibre circuit with the cladding-core mode conversion element that provides the core re-coupling of the optical power injected by TFBG to the fibre cladding. The cladding-core mode conversion efficiency is sensitive to the acceleration generated fibre bending. It is shown that the sensitivity of the device depends on the rate of the main core reflection versus cladding ghost reflection induced by the grating. The analysis of the core reflection power coupling on the angle of the grating tilt and the analysis of the cladding ghost reflection power coupling on the angle of the grating tilt is presented and the optimal parameters of the tilt and refractive index modulation are derived. The presentation gives the experimental results of the TFBG sensor prepared according to the optimization process.

DarcyTools: A Computer Code for Hydrogeological Analysis of Nuclear Waste Repositories in Fractured Rock  [PDF]
Urban Svensson, Michel Ferry
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26044

A computer code for simulation of groundwater flow and transport is described. Both porous and fractured media are handled by the code. The main intended application is the analysis of a deep repository for nuclear waste and for this reason flow and transport in a sparsely fractured rock is in focus. The mathematical and numerical models are described in some detail. In short, one may say that the code is based on the traditional conservation and state laws, but also embodies a number of submodels (subgrid processes, permafrost, etc). An unstructured Cartesian grid and a finite volume approach are the key elements in the discretization of the basic equations. A multigrid solver is part of the code as well as a parallelization option based on the SPMD (Single-Program Multiple-Data) method. The main application areas are summarized and an application to a deep repository is discussed in some more detail.

Demonstration of a Dynamic Braking System for Reduced Runaway Speed of Hydraulic Turbines  [PDF]
Urban Lundin, Johan Bladh
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.512007
Abstract: Reducing the overspeed during load rejection would benefit the mechanical and hydraulic systems in a hydropower station. This paper presents some selected results of a pilot installation of a dynamic braking system. The 4 MW dump load was installed and tested on a 10 MW Francis turbine unit. The results show that the overspeed reduction is obtained and compares well with simulation results. Further, a reduction in vibration levels is positive as well as the reduced time for stopping and possible resynchronization. It is argued that a similar system with continuous cooling could be used as an attractive alternative to spillway capacity.
Ananthidium, um gênero novo de Dianthidiini neotropical (Hymenoptera, Apoidea, Megachilidae)
Urban, Danuncia;
Revista Brasileira de Zoologia , 1990, DOI: 10.1590/S0101-81751990000200006
Abstract: ananthidium gen.n. is described the type species, anthidium inerme friese, 1908, is redescribed with notes on its variations and ananthidium dilmae sp.n., from belo horizonte, mg, brazil, is described.
Espécies novas de Anthodioctes Holmberg e notas sobre alguns Dianthidiini (Hymenoptera, Megachilidae)
Urban, Danuncia;
Revista Brasileira de Zoologia , 2002, DOI: 10.1590/S0101-81752002000600014
Abstract: the following new species are presented: anthodioctes rosanae sp. nov. and anthodioctes ayalai sp. nov. from méxico and anthodioctes misiutae sp. nov. from brazil. the male of moureanthidium bahianum urban, 1995 and the female of ananthidium dilmae urban, 1990 are described by the first time. notes and new occurrences of anthodioctes lunatus (smith, 1854) are given.
Sovereign Wealth Funds - new players on global financial markets
Dariusz Urban
Comparative Economic Research , 2009, DOI: 10.2478/v10103-009-0007-6
Abstract: The objective of this paper is analysis of Sovereign Wealth Funds, which are becoming increasingly important players in the international monetary and financial system. Those funds are attracting growing attention not only due to last investment activities in brand-name global firms, but also due to lack of transparency and information about themselves. The article consists of two part. In the first part of the paper based on the latest literature the author presents definitions of Sovereign Wealth Funds and main factors responsible for the rise and growth of those funds. The second part of the paper deals with investment characteristics made by the largest of them. The main conclusion of this paper is that empirical analysis do not prove the thesis that investment made by SWF's has a political background. The latest available data suggest that those funds avoid investing in sensitive sectors like defense, aerospace, high technology and transportation.
Vegetation of the ale Cemetery (Ljubljana)
Urban ilc
Hacquetia , 2009, DOI: 10.2478/v10028-009-0003-1
Abstract: The paper presents results of a vegetation survey of the cemetery of Ljubljana as a specific urban habitat with a high diversity of vegetation types. Seventeen different plant communities were found, mostly weed (hoe weed and garden communities), trampled and ruderal communities. This indicates frequently disturbed habitat with different microclimatic conditions than those in the surroundings.
R. Urban
Abstract: . We consider the Green functions $\mathcal G$ for second-order coercive differential operators on homogeneous manifolds of negative curvature, being a semi-direct product of a~nilpotent Lie group $N$ and $A=\R^+$. Estimates for derivatives of the Green functions $\mathcal G$ with respect to the $N$ and $A$-variables are obtained. This paper completes a previous work of the author (see \cite{pota, ejde}) where estimates for derivatives of the Green functions for the noncoercive operators has been obtained. Here we show how to use the previous methods and results from \cite{pota} in order to get analogous estimates for coercive operators.AMS subject classification 22E25, 43A85, 53C30, 31B25.Keywords Green function, second-order differential operators, $NA$ groups, Bessel process, evolutions on nilpotent Lie groups. Download Adobe PDF Compressed Postscript
Entrepreneurial cognitions: Linking willingness and ability expert scripts to self-efficacy and new venture creation decisions
Boris Urban
South African Journal of Industrial Psychology , 2008, DOI: 10.4102/sajip.v34i3.747
Abstract: In bringing the concept of expert scripts to bear upon the venture creation decision and following a script-scenario construction model the existence and degree of mastery of scripts are inferred from a selection of items consisting of paired script recognition and distracter cues. These cognition cues are then linked to motivation, operationalised with the general self-effcacy construct. Individuals with varying demographics who met qualifying criteria from an unrestricted range of businesses and industries (n = 161) were surveyed. Moderate support was found to consistently recognise and select statements that evidence expert entrepreneurial scripts. Associations with self-effcacy were modest, suggesting weak links between entrepreneurial cognition and motivation.
Entrepreneurial networking differences: An ethnic in-group and out-group analysis
Boris Urban
South African Journal of Industrial Psychology , 2011, DOI: 10.4102/sajip.v37i1.826
Abstract: Orientation: Researching entrepreneurship using a network perspective is important, as social networks are assets for small business owners struggling to survive in competitive markets. Research purpose: The research question of this study has focused on what we can learn about entrepreneurial networking, considering that there is an under-explored and unarticulated set of networking principles and practices which have not been previously analysed in terms of a multiethnic country context. Motivation for the study: Often the lack of network use is reported as a feature of entrepreneurs, who have less opportunity to utilise formal social capital features. Social networks provided by extended family, community-based or organisational relationships are often theorised to supplement the effects of education, experience and financial capital. Research design, approach and method: Based on hypothesised differences in networking ties, network assistance and support relationships, a survey was used to collect data on quantitative measures. Descriptive statistics were calculated and differential tests were conducted to test the hypotheses. Main findings: Results indicate that entrepreneurial networking is largely independent on group composition. Generally at least some aspects of networking are generic and as a consequence, a more integrated view of networking can be adopted. Practical/managerial implications: The practical value of the present study points to several areas of interest to entrepreneurs, policy makers and educators, through demonstrating the multifaceted nature of entrepreneurial networks for different groups and their explanatory potential in understanding networking. Contribution/value-add: Despite the importance of entrepreneurial networking, little empirical or theoretical research has examined the dynamics of networking in a developing country context such as South Africa, which has lower than expected total entrepreneurship activity. How to cite this article: Urban, B. (2011). Entrepreneurial networking differences: An ethnic in-group and out-group analysis. SA Journal of Industrial Psychology/SA Tydskrif vir Bedryfsielkunde, 37(1), Art. #826, 14 pages. doi:10.4102/sajip.v37i1.826
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