359 research outputs found
A Selective Harmonic Elimination Method for Five-Level Converters for Distributed Generation
No full textIn distributed generation, high power capability and high efficiency are very important requirements. For this reason, this paper proposes a new analytical procedure for selective harmonic elimination in five-level inverters operating at fundamental frequency. For each modulation index, the proposed method calculates all possible switching angles eliminating a specified odd harmonic from the output voltage. The method has limited computational complexity, simple and cost-effective real-time implementation, and full capability of integration with closed loop control. Simulation and experimental results highlight full elimination of selected harmonic
Current Status of Philanthropy in India
No full textThe paper makes an attempt to provide an overview of philanthropy in India. On the one hand, it describes, though briefly, the historical growth of philanthropy and on the other hand it provides a contemporary picture as well. It also deals with the legal framework with which philanthropic institutions function in this country. Further, it provides a glimpse of the tax laws vis-à-vis donations (giving) and also discusses the legal status of the philanthropic institutions
Optimal Low Switching Frequency Pulsewidth Modulation of Current-Fed Three-Level Converter for Solar Power Integration
No full textLarge-scale photovoltaic energy conversion systems have been installed at many places across the world and they handle higher power levels. In high power conversion, low device switching frequency operation is preferred in order to satisfy the thermal constraints of semiconductor devices and also to improve efficiency. However, low device switching frequency operation leads to higher total harmonic distortion (THD) of the converter output currents. Synchronous optimal pulsewidth modulation (SOP) is an emerging low device switching frequency modulation technique, which has been successfully implemented for voltage source inverters without compromising on THD. The goal of our research is to propose, analyze, and implement a modified SOP technique for current source inverter topologies. The additional switching constraints for these inverter topologies have been included in the modified SOP technique. The experimental results obtained from a low-power prototype demonstrated its effectiveness
Galactocerebroside and other secondary metabolites of sea mouse Chloeia parva1-4
No full textDepartment of Chemistry, University College of Science, University of Calcutta, 92, A. P. C. Road,
Kolkata-700 009, India
E-mail: [email protected] Fax : 91-33-23519755
Manuscript received 15 October 2003
Novel galactocerebrosides derived from 2-amino-4-alkene-1,3-diol along with fatty acid methyl esters (FAME), cholesterol, ceramides, 1-O-acylglycerols and 1-O-alkylglycerols have been isolated from a sea mouse Cllloeia parva. The structure of galactocerebrosides is established from one-dimensional [1H, homodecoupling and 13C (NDC and DEPT-135)] NMR spectral studies of the metabolite and its acetate as well as two-dimensional (COSY -90, X-H correlation optimized for IJC-ll) NMR spectral studies of the latter. The remaining components isolated have been characterized from chemical studies and detailed NMR spectral analyses of parent materials and products derived thereof. The lengths of the alkyl and acyl chains in galactocerebrosides, FAME, ceramides, 1-O-acylglycerols and 1-O-alkylglycerols are established by gas chromatographic analysis of appropriate derivatives
Longevity: Trends, uncertainty and the implications for pension systems
No full textThis paper presents historical trends in life expectancy in the United Kingdom and other countries and discusses how these trends might evolve over the coming decades. The paper argues that the expected increases in longevity are likely to have significant implications for the structure of pension systems in the future. Individuals, businesses and governments have already responded to these expected increases – for example by working longer, closing defined-benefit pension schemes or introducing parametric reforms to the state pension system – and are likely to change their behaviours further in the future. The issue is complicated by the fact that future longevity trends are uncertain. This makes it more difficult to allocate longevity risk efficiently and fairly across the different economic agents, while making it also more difficult to guarantee the sustainability of the system overall. The paper shows though that innovative solutions to this challenge are being developed, from businesses moving towards hybrid defined-benefit/defined-contribution pension schemes, to governments introducing mechanisms which automatically split the financial burden arising from future increases in life expectancy between state and individual, to businesses taking advantage of new products being developed to transfer any risk to the capital markets. --Pensions,Uncertainty,Financial markets,Longevity,Pension liabilities
Back to the drawing board: The economic crisis and its implications for pension provision in the United Kingdom
No full textThis paper focuses on an issue, which so far has received relatively little attention by policy makers and the media, namely that the economic crisis has highlighted inherent weaknesses in existing pension systems in many countries. Using the example of the UK, the paper argues that the economic crisis will usher in further changes to the future provision of pensions, with the role of the private and public sectors likely to evolve in the years ahead. To support this argument, the paper first presents the pension landscape in the UK prior to the crisis, which was dominated by the closure of defined benefit pension schemes in the private sector and the government’s reform efforts. The paper then describes the impact of the economic crisis from both a macroeconomic and financial perspective on all aspects of the pension system, from the government’s deteriorating public finances to the collapsing funding position of occupational defined-benefit and defined-contribution schemes. The paper concludes by suggesting that the crisis has left the British pension system in a weakened state and that it is unlikely that it will return to its “pre-crisis” status once the economy recovers from the crisis. --Economic crisis,Pension finances,Pension systems,Defined benefit pensions,Pension liabilities,Government policy,Financial markets
Plastids in Variegated Leaves
No full textThe chloroplast is a unique organelle in photosynthetic eukaryotes, essential for fulfilling the complex and diverse functions required in green plant tissues. To support these functions, chloroplasts must be fully developed and operational. Their development is regulated by an intricate network of external and intrinsic factors. Despite the necessity of functional chloroplasts, many plant species exhibit variegated phenotypes characterized by leaves containing pale green, yellowish, or white segments, which often lack functional chloroplasts. The physiological and ecological advantages of this phenomenon remain unclear, as leaf variegation is typically perceived as detrimental to optimal photosynthetic efficiency. However, under specific adverse environmental conditions, the adaptive benefits of variegation may outweigh the drawbacks associated with the absence of fully developed chloroplasts. To gain a deeper understanding of the molecular origins and physiological implications of variegation, it is essential to investigate the ultrastructure of plastids in non-photosynthetically active leaf cells under physiological and various stress conditions. Therefore, this chapter focuses on the histological differences between the mesophyll tissue of uniformly green leaves and the yellow or white sectors of variegated leaves. Numerous ultrastructural studies suggest that the plastids in the non-green leaf sectors represent a distinct type of plastid, referred to as “albinoplasts.” The primary objective of this chapter is to highlight the key ultrastructural differences between normal plastids and the albinoplasts observed in the non green leaf sectors. This analysis considers a broad spectrum of molecular factors contributing to variegated phenotypes in both dicotyledonous and monocotyledonous plant species
Management of a 3-year-old child with ambiguous genitalia
No full textTrue hermaphrodites have characteristics tissue both sex in the form of presence of vagina uterus, fallopian tubes and ovaries as in female and presence of testis seminiferous tubules but penis as in penoscrotal hypospadias and bifid scrotal sac confuses as well developed labia majora. Determination of sex as per parents view in our social set up. The case was provisionally diagnosed as intersex. Total abdominal hysterectomy, bilateral salphingo-oophorectomy and colpectomy were conducted. A 3-year-old child referred by a pediatrician to Nalanda Medical College, child surgical department for investigation and management of his ambiguous genitalia having following features like, urine was not passing from the tip of penis; penis along with apparently looking female genitalia was taken under treatment. Examination under general anesthesia showed a presence of both male/female internal genitalia and gonads with features of external genitalia of both sexes. After total abdominal hysterectomy and human chorionic gonadotrophin treatment growth of phallus and testicle was noted. The child was made male after extirpation of female genitals. This case illustrates that gender correction can be made as per patients consent in adult but at this stage social customs and parents consent dictated the treatment
OPTIMAL PULSE WIDTH MODULATION OF MULTILEVEL INVERTERS FOR MEDIUM VOLTAGE DRIVES
No full textPh.DDOCTOR OF PHILOSOPH
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