The project suggests the development of a low cost fuel cell inverter system. The approach consists of a three-terminal push-pull inverter to boost the fuel cell voltage. High-frequency ac link conversion offers a possible way to reduce the number of power stages, in the form of a cycloconverter. The design minimizes overall system cost including energy storage and management. The design provides low-ripple current-controlled interfacing to the fuel-cell stack, an intermediate-voltage battery energy storage buffer, and an ac-link output inverter. The circuit is based on square-wave cycloconverter technology, combined with a simple approach that produces a patent-pending “PWM cycloconverter” modulation process. Modulation technique includes multiple carrier PWM which is a direct extension of conventional PWM. The approach keeps the number of stages and magnetic elements low while providing galvanic isolation. The design provides excellent performance with a minimum filter components and a simple control.
This book mainly emphasizes on novel optimization techniques namely ‘Circular Method of Optimization’ and ‘Spherical Method of Optimization’. The author has programmed these techniques in MATLAB 7.7. Circular Method of Optimization mainly concerns with the constraint optimization problem with two independent variables and Spherical Method of Optimization mainly concerns with three independent variable problems. These techniques were implemented on Class A chopper and then the results were implemented on actual hardware of the same circuit. Finally the software and hardware results were compared to prove the usefulness of these techniques.
Family Bignoniaceae comprises about 120 genera and 800 species. It is noted that plants belonging to Bignoniaceae are used medicinally in traditional medicine for their significant bioactivities. It was deemed of interest to subject one of these plants namely Mayodendron igneum Kurz to bioactivity-guided fractionation for exploring the main phytoconstituents responsible for its bioactivity since there were few reports concerning this subject in literature. M. igneum grows wildly in China. It is planted as a vegetable for its high nutritional value and as an ornamental plant for its spectacular flowers. Biological screening of different extracts of M. igneum Kurz for antioxidant and hepatoprotective activities revealed that both ethyl acetate and ethanol extracts exhibited the strongest activity. Fractionation of these active extracts led to isolation of phenolic compounds. Biological screening of different extracts of M. igneum for in vitro cytotoxic activity revealed that petroleum ether extract exhibited the strongest activity. GC/MS analysis of lipoidal matter of petroleum ether extract was studied. Fractionation of petroleum ether extract yields terpenoidal compounds.
In this book we have studied the out-of-plane, c-axis resistivity, ?c(T), of Ca doped Y(Ca)Ba2Cu3O7-? high-Tc superconductors (cuprates). Our aim was to model the c-axis resistivity by considering the full impact of the pseudogap (PG) in the electronic density of states (EDOS) in cuprates and to understand the role of the k (wave vector) on hopping integral along the c-direction. We have used the formalism developed by T. Xiang et al. (Phys. Rev. B 73, 134510 (2006)) to fit the experimental resistivity data for high quality single crystals of Y(Ca)Ba2Cu3O7-? over a wide range of hole content in the CuO2 plane, p. We have found systematic behavior of maximum pseudogap energy scale, ?, with doping. It is also found that the coefficient, ?c, determining the extent of linearity of ?c(T) is also strongly p-dependent. The analysis also reveals that the formalism developed by T. Xiang et al., fails to produce reliable estimates of ? and ?c for the overdoped compounds. The extrapolated values of ?(p) tends to vanish at p ~ 0.2. We have discussed the various features of the analysis in detail in this monograph.
The agricultural workers of Sorbhug area of Barpeta District using excessive amount of pesticide in their cultivated land.A monitoring was conducted in the area on exposed workers who sprayed pesticide and compared to control groups. Work practice and hygienic measure taken at the time of spraying operation was taken in to consideration In health risk assessment process different toxicological symptoms were observed as in the control group such as depression, cold ,watery and itchy eyes,dizzyness,feeling tired, ulcerative colitis ,sinus problem, stomach problem, vomiting,headache,first heart rate, blurred vision. Training of agricultural workers, restricted use of pesticides,workshop; alternative use of pesticide like herbal pesticide are recommended.