A quad DC source switched three-phase multilevel DC-link inverter topology.

The concept of an isolated DC source cascaded multilevel inverter finds good solutions for generating quality output voltage for low-medium power applications. It shapes the output voltage from three levels into a number of steps closer to a sinusoidal shape using small DC sources or batteries. Several advantages have been sighted like lower voltage stress and bearing noise, and lesser THD. However, a common issue in the MLIs is the total components required which increase with the rise in voltage levels. This paper proposes a three-phase MLI design having several isolated quad voltage source modules including an H-Bridge inverter. The design suggested claims reduced switching components for current conduction paths showing improved output quality. The operational features of the suggested MLI have been analyzed using Matlab/Simulink software, furthermore, an experimental module is constructed for demonstrating the effectiveness of the simulated results.

Experimental design and analysis of advanced three phase converter for PV application with WCO-P&O MPPT controller.

Photovoltaic (PV)-based power generation systems are becoming increasingly popular as a due to its high performance and cleanliness. Several factors influence the performance of a PV system, including shadowing effects. PV systems employ MPPT methodologies to obtain the power from PV array. Conventional MPPTs works well under normal conditions when there is no shadow effects or partial shading. The presence of partial shading affects the system performance and generates several power peaks. This complicates the process of finding out of the global peak (GMPP) with improved tracking efficiency and reduced settling time including conversion efficiency. This work proposes three hybrid MPPT techniques: Water Cycle Optimisation-Perturb and Observe (WCO-PO), Artificial Neural Network Supported Adaptable Stepped-Scaled Perturb and Observe (ANN-ASSPO), Grey Wolf Optimisation-Modified Fast Terminal Sliding Mode Controller (GWO-MFTSMC), and two conventional MPPT techniques WCO and P&O have been implemented. The proposed system utilizes interleaved boost converter with three phase. The performances of proposed hybrid MPPTs strategies were compared in terms of output voltage, output current and extracted power. The comparison also includes conversion efficiency and average settling time. To analyse the performances, four different cases have been used to test the efficacy of hybrid MPPTs under changing climatic conditions. The MATLAB/Simulink tool has been used to analyze the PV system performances. In the three hybrid MPPT techniques, WCO-PO has performed better when compared to other two hybrid MPPTs in terms of conversion efficiency (99.56%) and settling time (1.4 m).

Batch adsorption studies for chromium removal.

The adsorption of hexavalent chromium (Cr (VI)) on pongamia (Pongamia pinnata) leaf powder was investigated in the present study. Crude pongamia leaf powder (CPLP) and nitric acid treated pongamia leaf powder (APLP) were used as adsorbents. CPLP did not show remarkable adsorption efficiency but APLP had good adsorption capacity and adsorption removal efficiency. The parameters studied included the contact time, initial solute concentration and pH. The optimum pH for removal of chromium was found to be 2 for both CPLP and APLP. The best contact time for maximum chromium adsorption was 165 minutes for CPLP and APLP. CPLP and APLP showed good adsorption capacity and adsorption removal efficiency at an initial chromium concentration of 5 mg/L. The adsorption was found to follow Langmuir and Freundlich isotherms for CPLP and APLP but they showed good curve fit for Freundlich isotherm.

Quantitative DNCB epicutaneous sensitization in leprosy patients and controls.

Status of non-specific cell mediated immunity in 49 leprosy patients classified according to Ridley & Jopling scale and 16 non leprous controls was studied using epicutaneous sensitization with DNCB and quantitatively grading the degree of sensitization with DNCB and quantitatively grading the degree of sensitization and Mx. test with 1 TU PPD. The effect of dapsone administration on CMI responses was also observed. There was no gross depression of CMI responses as made out by epicutaneous sensitization to DNCB but quantitative grading of responses revealed a subtle depression of CMI responses progressively increasing from II to LL end of spectrum. Mx. testing with 1 Tu PPD did not appear to be a good parameter to study the CMI status. Dapsone administration did not alter the CMI responses.

Efficacy of co-trimoxazole in Donovanosis. A preliminary report.

Co-trimoxazole (Septrin, Wellcome) was prescribed in a dose of two tablets twice daily for the treatment of 10 patients with Donovanosis. All the patients responded well to this treatment, and the ulcers healed completely within 10 days in eight patients and within 14 days in the remaining two. Ten days' treatment with 40 tablets of co-trimoxazole is suggested as sufficient to treat Donovanosis. No adverse reactions were noted in any patient.

Leucocyte migration inhibition test in leprosy patients across the spectrum of leprosy.

The leucocyte migration inhibition test (LMIT) using Dharmendra's antigen was performed in 21 cases of leprosy classified according to Ridley Jopling Scale (1966). The degree of migration correlated well with the classification as expected thus confirming the immunological validity of Ridley-Jopling classification.