Optimal passive filter design for effective utilization of cables and transformers under non-sinusoidal conditions

Transformers and cables have overheating and reduced loading capabilities under non-sinusoidal conditions due to the fact that their losses increases with not only rms value but also frequency of the load current. In this paper, it is aimed to employ passive filters for effective utilization of the cables and transformers in the harmonically contaminated power systems. To attain this goal, an optimal passive filter design approach is provided to maximize the power factor definition, which takes into account frequency-dependent losses of the power transmission and distribution equipment, under non-sinusoidal conditions. The obtained simulation results show that the proposed approach has a considerable advantage on the reduction of the total transmission loss and the transformer loading capability under non-sinusoidal conditions when compared to the traditional optimal filter design approach, which aims to maximize classical power factor definition. On the other hand, for the simulated system cases, both approaches lead to almost the same current carrying (or loading) capability value of the cables. © 2014 IEEE.This work is supported by Turkish Republic Ministry of Science, Industry and Technology and BEST Transformers Co. under the project number of 01008.STZ.2011 - 2

An algorithm for optimal sizing of the capacitor banks under non-sinusoidal and unbalanced conditions

In non-sinusoidal and unbalanced systems, optimal sizing of the capacitor banks is not a straightforward task as in sinusoidal and balanced systems. In this paper, by means of qualitative and quantitative analysis, it is interpreted that the classical capacitor selection algorithm widely implemented in Reactive Power Control (RPC) relays does not achieve optimal power factor improvement in non-sinusoidal and unbalanced systems. Accordingly, a computationally efficient algorithm is proposed to find the optimal capacitor bank for smart RPC relays. It is further shown in a simulated test case by using Matlab software that the proposed algorithm provides better power factor improvement when compared with the classical algorithm. It is also figured out from the simulation results that both algorithms cause almost the same harmonic distortion and unbalance deterioration levels in the system

A filter design approach to maximize ampacity of cables in nonsinusoidal power systems

This paper presents an optimal design of the C-type passive filters for the effective utilization of the power cables under nonsinusoidal conditions based on maximization of the harmonic derating factor (HDF) of a power cable, where maintaining the load true power factor at an acceptable range is desired. According to IEEE Standard 519, the total harmonic distortions of the voltage and current measured at the point of common coupling are taken into account as main constraints of the proposed approach. The presented numerical results show that the proposed approach provides higher current carrying capacity, or ampacity of the cables under nonsinusoidal conditions when compared to the traditional approaches based on minimization of the current total harmonic distortion and maximization of the true load power factor. A numerical case study is presented to demonstrate the proposed approach

Optimal design of single-tuned passive filters using response surface methodology

This paper presents an approach based on Response Surface Methodology (RSM) to find the optimal parameters of the single-tuned passive filters for harmonic mitigation. The main advantages of RSM can be underlined as easy implementation and effective computation. Using RSM, the single-tuned harmonic filter is designed to minimize voltage total harmonic distortion (THDV) and current total harmonic distortion (THDI). Power factor (PF) is also incorporated in the design procedure as a constraint. To show the validity of the proposed approach, RSM and Classical Direct Search (Grid Search) methods are evaluated for a typical industrial power system

Clinical decision analysis: Incorporating the evidence with patient preferences

Decision analysis has become an increasingly popular decision-making tool with a multitude of clinical applications. Incorporating patient and expert preferences with available literature, it allows users to apply evidence-based medicine to make informed decisions when confronted with difficult clinical scenarios. A decision tree depicts potential alternatives and outcomes involved with a given decision. Probabilities and utilities are used to quantify the various options and help determine the best course of action. Sensitivity analysis allows users to explore the uncertainty of data on expected clinical outcomes. The decision maker can thereafter establish a preferred method of treatment and explore variables which influence the final clinical outcome. The present paper reviews the technique of decision analysis with particular focus on its application to clinical decision making

CSF oligoclonal bands in multiple sclerosis

Objective: To study the significance of oligoclonal bands in neurological disorders, specifically in Multiple Sclerosis (MS). Methods: The study was designed to assess the sensitivity and specificity of the test methodology of CSF electrophoresis by performing the retrospective analysis of CSF samples sent for oligoclonal bands (OCB). A total of 603 samples were received by the Clinical Laboratories, Department of Pathology of The Aga Khan University, during a period of 54 months (January 1993-June 1997). All of these samples were analyzed by performing CSF protein electrophoresis. One hundred thirty three out of 603 samples showed evidence of OCB. Out of these, 24 patients were registered with Section of Neurology, Department of Medicine, The Aga Khan University Hospital. These 24 patients were finally selected for analysis. Relevant clinical details such as age, sex and clinical presentations were recorded. Results: Fifteen (62%) out of 24 patients with positive OCB were diagnosed as cases of MS. Four (17%) patients were diagnosed to have subacute sclerosing panencephalitis (SSPE). Five (21%) patients were having other inflammatory neurological disorders. Conclusion: The overall relative sensitivity and specificity for multiple sclerosis were found to be 100% and 62.5% respectively. Lack of specificity was attributed to the fact that OCB were positive in other neurological disorders as well

Luxury brands on Instagram: A netnographic approach

The present research concerns a netnography study from June 1st 2020 to January 1st 2021on Instagram communication of six luxury brands: Louis Vuitton, Prada, Gucci, Dior, Chanel and Burberry. Five variables were taken into consideration: number of followers, number of posts, average comments, average likes and engagement rate. This qualitative study reflects the impact of digital transformation on the luxury market. Overall, results demonstrate luxury brands similarities in their Instagram communication strategy - Louis Vuitton and Gucci; Dior and Chanel; Prada and Burberry. With our findings, we were able to associate these luxury brands with the core dimensions of brand coolness. Implications of these findings are discussed with future research directions suggested.info:eu-repo/semantics/publishedVersio

Indigenous Uses of Some Important Ethnomedicinal Herbs of Ayubia National Park, Abbottabad, Pakistan

This paper is based on the results of an ethno botanical research project conducted in Ayubia National Park. The people of the park have always used the medicinal herbs for various ailments and are dependent on the plants in their surroundings for food, shelter, health, medicines, fodder and various cultural purposes. A total of 21 important herbs belonging to 19 Families were recorded which were used medicinally by the local inhabitants. About 100 informants were interviewed in this regard. The precious ethno botanical knowledge is disappearing very fast, so this study could be helpful in conserving the precious knowledge. Podophyllum emodi Wall. ex Royle and Viola canescens Wall. ex Roxb. are found vulnerable to harvesting