A Review on Control Strategies and Topologies of Multi Level Converter System

In recent decades, high-performance and medium voltage energy management for academia and industry have been attracted by multi-level converter topologies. In addition, the multi-level principle is used without decreasing the inverter power output to synthesise the harmonic distortion on the output waveform. For the reduction of harmonic distortion in the output waveform, the multi-level principle is used. The following topologies are presented: diode clamped inverters (neutral point clamped), condenser clamped (flying condenser), multi-level cascading (dc source, etc.) and the most effective modulation methods built for this converter category: multi-level, selective harmonic removal and space m vectors. A series of different topologies are given in this paper. Multi-level inverters have been gaining popularity in research teams and in the production of industrial applications for high and medium voltage applications for 20 years. Moreover, compared to a conventional converter, multi-level inverters can generate switched waveforms with reduced harmonic slopes. Recently, multi-level inverters have increased interest in their ability to generate high-quality wave forms at lower frequencies; the multi-level topology used in dynamic restaurant voltages reduces the harmonic distortion of the inverter output waveform without inverter output losses. By integrating control techniques for multi-level inverters, this paper discusses the most common topologies, making their implementations flexible in some power applications in many industrial areas

ANTIDEPRESSANT ACTIVITY OF THYMOQUINONE POSSIBLY THROUGH INVOLVEMENT OF CORTICOTROPIN RELEASING FACTOR

  Objective: Present study aimed to evaluate the antidepressant-like activity of thymoquinone (TQ) in unstressed and stressed condition and to explore the possible underlying mechanism for this activity.Methods: TQ (5, 10, and 20 mg/kg) and fluoxetine per se were administered to the unstressed and stressed mice; immobility periods were observed using forced swim test (FST) and tail suspension test (TST). Effect of corticotropin-releasing factor (CRF)-1 antagonist on antidepressant-like activity was also evaluated. The mechanism of action was also explored by measuring plasma corticosterone levels.Results: TQ (20 mg/kg) and fluoxetine per se significantly decreased immobility periods in stressed mice indicating significant antidepressant-like activity under stress. There was no significant effect on locomotor activity of the mice on treatment with TQ and fluoxetine per se. It significantly decreased plasma corticosterone level. Antalarmin (a CRF-1 receptor antagonist) significantly attenuated TQ induced the antidepressant-like effect in both FST and TST.Conclusion: TQ significantly produced antidepressant-like activity in mice possi‑bly through inhibiting CRF activity and decreasing plasma corticosterone levels.Â

Analysis and design of an auxiliary commutated full bridge DC/DC converter for low voltage and high current applications

The analysis and design of an auxiliary commutated Full Bridge dc/dc converter topology including the effect of leakage inductance of the output transformer is presented in this thesis. In applications where the transformer has high turns-ratio between the primary and secondary windings, the value of leakage inductance is relatively high. This high value of leakage inductance, however, is not large enough to achieve the zero voltage switching (ZVS) of the converter over the entire range of operating load conditions, but can be effectively used in minimizing the circulating current of the auxiliary commutation circuit used for achieving ZVS. The operating principle of the circuit is demonstrated, and the steady state analysis is performed. Based on the analysis, a criterion for optimal design is given

Bioadhesive Buccal Tablets of Aminophylline by Direct Compression Method

Buccal administration of drugs which exhibit a low oral bioavailability is a useful method to achieve higher bioavailability. The objective of present research work is to design and evaluate the prolong release bioadhesive buccal tablet of Aminophylline with goal to increase the bioavalability, reduce dosing frequency and improve patient compliance. Aminophylline is ethylenediamine salt of theophylline. Buccal tablets of aminophylline were prepared by direct compression using different  bioadhesive polymers such as HPMC K4M and Carbopol 934-P. The prepared tablets were subjected to post friability, Hardness thickness, weight variation, drug content and swelling index, bioadhesive strength, In-vitro drug release. Keywords: Aminophylline, HPMC, direct compression method, Swelling index, in-vitro drug release

Transmission Wheeling Pricing in Embedded Cost Using Modified Amp-Mile and MVA Utility Factor Methods

Transmission wheeling pricing is one of the decisive aspects of present open access electricity market. Various methods are available for transmission; however, no method is proved to diverse operating conditions of power system. These methods are not able to quantify the full recovery of embedded cost. All the variables i.e. remaining charges, used circuit capacity are not counted in the existing methods. This Paper explicates two methods, Modified Amp – Mile method and MVA Utility Factor method, to recover embedded cost. Modified Amp-Mile method is customized form of existing Amp-Mile method. In the MVA Utility Factor method, cost allocation is based on marginal participation (MP). It evaluates the cost, using sensitivity analysis of network power. The proposed methods are tested on an IEEE 6 bus system and further verified on Hadoti region real 37 bus system. All the results are presented in Full Recovery Model (FRM) and Partial Recovery Model (PRM)