Frequencies Dominations for Different Rating of Distribution Transformer under Transients

Power transients faults on high voltage lines are prominently due to high frequency transients. These transients affect the predicted life and efficiency of equipment. The Fast Fourier Transform (FFT) is helpful in analysing the effect of high frequencies and Frequency Response Analysis (FRA) provide support in diagnosis and detection of deformation in a transformers. The major aim of this study is to analyse the incorporation of frequencies based on resonating core of a particular transformer. Using transfer function method an impedance change in transformer has been observed when equipment is subjected to high voltage transients. The effect of change in impedance is that it degrade the life of a core with respect to time. In this paper, research that has been done already on Transformers of different ratings i.e. 100, 50 and 30 kVA are studied and then an experiment is performed on 50-kVA transformer. It was concluded that the core of a transformer having rating equal or less than 50 kVA practically shows single resonance behavior while above 50 kVA for instance 100-kVA transformer core resonates twice. In actual, result defines the core deviating frequency with respect to the rating of a transformer

Wages and Immigrant Occupational Composition in Sweden

This paper examines the relationship between immigrant occupational composition and wages in Sweden. Effects of changes in proportion of immigrant workers in different occupations on the wage levels of both natives and immigrants are estimated. Our results suggest that increases in immigrant density have only small effects on wages and that the negative relationship between wages and the proportion of immigrant workers in an occupation, observed in data, is almost entirely accounted for by measured and unmeasured worker skills. These results suggest that wage differences across occupations with different densities of immigrants are mainly due to quality sorting and to a lesser extent due to the existence of discrimination.immigrants, refugees, occupational composition, quality sorting, wages

Immigrant composition and wages in Canada

This paper examines the relationship between immigrant-composition and wages of different occupations and different industries in Canada. It reports the effects of change in proportion of immigrants on the wage level in 1996 for both male and female Canadians and immigrants. First all immigrants are considered homogeneous and thereafter they are distinguished according to a wide array of criterion and a full spectrum of results are presented. These results suggest that for immigrants the aggregate relationship of income with immigrant composition is fairly small, unless they are subcategorised into specific groups (e.g. non-white immigrants, immigration after 1990). The corresponding wage penalties for Canadians are more uniform across the different subgroup specifications and decomposition of the data

Stability of Gravastars with Exterior Regular Black Holes

This paper examines the stability of thin-shell gravastars in the context of regular spacetimes (Bardeen and Bardeen-de Sitter black holes). We apply cut and paste approach to construct gravastars through the matching of interior non-singular de Sitter geometry with exterior regular black hole. This model contains three regions, i.e., interior, thin-shell and exterior. The interior and exterior regions are connected at thin-shell. We investigate physical viability of the developed model by the energy conditions and explore its stability by using radial perturbation about the equilibrium shell radius. It is found that thin-shell gravastars show large stable regions for the Bardeen-de Sitter black hole as compared to the Bardeen black hole. It is concluded that stable regions exist near the formation of expected event horizon.Comment: 17 pages, 5 figure

Financial model for private finance initiative projects applied to school buildings

Private Finance Initiative (PFI) has become a major procurement method in the UK and worldwide. The number of signed PFI deals is growing, but competition is restricted to those companies that are able to afford the initial investment. The bidding cost of PFI projects are high, and bidding companies are not compensated if the client does not award them the project. This is the reason behind several recent high-profile tender xvithdra« als. and is considered a major barrier for private companies wanting to take part in the bidding process. There is an obvious need for a tool to enable construction organizations to participate in PFI projects; one that can support these organizations in a decision-making process that is compatible with their project selection strategies, and will allow them to bid for PFI projects with clearer goals and reduced costs. A computer-based financial model was developed to predict the cost and cash flow of PFI projects, enabling project teams to assess investment decisions at the tendering stage. The proposed model consists of four modules to identify the required building area, predict the construction cost, distribute the occupancy cost, and predict the cash flow of the project. The output of the model provides the project investment results, such as the Net Present Value (NPV), Internal Rate of Return (IRR), Debt Service Coverage Ratio (DSCR), payback period and investment growth ratio. The model can predict the unitary payment but also allows the user to define the unitary payment. The reports of the model contain the cash flow and investment ratio for both types of unitary payment. The model attempts to provide the information required to assess the feasibility and affordability of the project. It gives the private sector the chance to assess the project before they spend unrecoupable funds on the project. It allows the public sector to determine the project cost, cash flow, unitary charge, and provide the information to be used for the Public Sector Comparator. The data required for the development of the model was collected from different sources. The model was initially developed on spreadsheet software: the final version was transformed into a web-based model using the Hypertext Preprocessor (PHP) and Javascript programming languages. The completed model was then sent to many practitioners for validation and assessment of both the concept and numerical application. The responses received show the valuable role the model could play in PFI projects.Ministry of Higher Education, Saudi Arabi

The Relationship Between Leptin and PCOS

Background: The ob gene produces a leptin hormone that works as a satiety signal to the hypothalamus. Leptin may have a role in polycystic ovary syndrome (PCOS) via its role on obesity and insulin resistance. Materials and Methods: A prospective, retrospectives cross- sectional study included 78 females student aged 17-25 years. The retrospective data included clinical, anthropometric and hormonal profile of each subject. Leptin concentration was measured by enzyme absorbent by BioVendor Human Leptin ELISA. Statistical analysis was performed by IBM SPSS Statistics 21.0 for Windows XP (IBM, USA). Results: leptin found to be significantly higher in those women with PCOS than in women without PCOS (p-value 0.037). Also, Overweight/Obese subjects had higher leptin level (22.85 ng/ml) than non-overweight/non-obese subjects (8.82 ng/ml) with (p-value <0.05). OW/Ob group showed higher frequency of family history of PCOS and diabetes, irregular menstrual cycle (IP) and high Ferriman-Gallwey score. Leptin is significantly correlated with insulin, testosterone, BMI, DHEAS, progesterone, FAI and PCOS. Conclusion: PCOS, overweight and obese subjects exhibit high leptin level