In this paper a control scheme for three phase seven level cascaded H-bridge inverter for grid tied PV system is presented. As power generation from PV depends on varing environmental conditions, for extractraction of maximum power from PV array, fuzzy MPPT controller is incorporated with each PV array. It gives fast and accurate response. To maintain the grid current sinusoidal under varying conditions, a digital PI controller scheme is adopted. A MATLAB/Simulink model is developed for this purpose and results are presented. At last THD analysis is carried out in order to validate the performance of the overall system. As discussed, with this control strategy the balanced grid current is obtained keeping THD values with in the specified range of IEEE-519 standard.
<p>This paper, introduced an expression of Economic Efficiency Measure (EEM) to permit quick evaluation for replacement of faulty induction motor with alternative (new or refurbished motor) for lowest life-cycle cost based on efficiency and rated-load conditions. This approach, simplifies the process for evaluating the energy efficiency to mere proportionate factor called as EEM. During the operating phase, the motor losses correspond to extra energy consumption, based on various parameters like motor operating conditions, operating hours, operating costs, fault factor, depreciation factor and fixed costs. The approach is effective in addressing the global issue on replacement of the faulty motor that needs a comprehensive analysis and mathematical expression. Compared to other alternatives the EEM provides a simple but effective and reliable means to asses, the feasibility of replacing or refurbishing the faulty motor. A detail analysis here would establish how much the present approach is effective in determining the replacement for a faulty induction motor either by a new one or refurbished one of corresponding rating.<strong></strong></p>
Introduction: In view of the present Coronavirus Disease 2019 (COVID-19) pandemic it is of utmost importance to look out for the ‘trojan horse’ that is the asymptomatic population who are potential for spreading the disease. Healthcare Workers (HCWs) are the most vulnerable group. The possibility of having the infection does not always correlate well with the symptoms. It urges the need for development of certain special plans beyond continuous surveillance and symptom monitoring. Aim: To explore asymptomatic COVID-19 infection among HCWs as a potential source of transmission. Materials and Methods: This hospital-based cross-sectional study was conducted at Medical College and Hospital, Kolkata , West Bengal, India, from June 2020 to September 2020. The data were collected from 714 HCWs over a period of three months of study period, with the help of a standard questionnaire and blood sample was analysed by serological assessment of Immunoglobulin G (IgG) for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by EUROIMMUN Kit, EnzymeLinked Immunosorbent Assay (ELISA). Epi info software 7, available from the World Health Organization (WHO) site was used to manage and analyse the data. Results: The mean age was 35.30±11.79 years. Out of 714 people, 54.8% (391/714) were male and 45.2% (323/714) were female. In this survey, 9.16% of HCWs in COVID-19 designated duties were IgG positive; whereas 21.89% of HCWs designated in other parts of area were detected to be IgG positive. Seroprevalence was least amongst nursing staffs with 5.41% (8/148); among doctor’s it was 9.62% (41/426). Most interestingly among ward boys and cleaners this prevalence was found to be 29.90% (29/97) being the highest. Overall seroprevalence for IgG against SARS-CoV-2 was found to be 12.75% (91/714). Conclusion: This serosurvey at this tertiary COVID-19 care facility is a unique venture to look for the possible sources of super-spread. The high rate of sero-positivity among ward boys and cleaners might be due to their lack of knowledge and training regarding steps to prevent a droplet borne pandemic. This study also points out that if adequate precautions are taken, infectivity is not to an alarming extent, even in a fullfledged COVID-19 care hospital.
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