Analysis, Design, and Control of a Single-Phase Single-Stage Grid-Connected Transformerless Solar Inverter

As energy utilization is increasing with the rise in the world’s power demand, the traditional energy sources are depleting at a high pace. It has led to attention drawn towards inexhaustible energy resources. There is a huge augmentation in the power generation from renewable energy sources (RES) like wind, solar, hydropower, biomass, etc. to reduce the stress on conventional energy sources like fossil fuels, oil, gas, etc. There has been a steep increase in interest for wind and solar energy systems. PV energy has been growing swiftly in the past two decades which made it most demanded power generation system based on RES. This worldwide requirement for solar energy has led to an immense amount of innovation and development in the Photovoltaic (PV) market. The Conventional grid-connected PV inverter was either with DC/DC converter or without DC/DC converter. These inverters were isolated using a transformer either on the grid (AC) side as a low-frequency transformer or as a high-frequency transformer on the DC side. Elimination of the transformer leads to a galvanic connection between the grid and PV module. This gives rise to the flow of leakage current which is disastrous for the system when it exceeds a specific value. Thus, minimization of this leakage current after the removal of the transformer has been an interesting topic explored by many researchers. Many topologies have been proposed targeting reduction in this leakage current either by 1.) Directly connecting the PV negative with neutral of utility grid or 2.) Disconnecting the PV panel side from AC side. This generally involved addition of more switches or diodes or supplementary branches to disconnect during the freewheeling period. Generally, the above-mentioned ways lead to a reduction in efficiency due to increased losses or complex circuitry. The motivation of this thesis is to design a transformerless inverter for single-phase PV grid-tied system with a smaller number of devices and still has minimum ground current. It discusses the prevailing inverter topologies in detail and then explains the modes of operation of the proposed inverter. A simple control strategy has been derived and passive elements of the inverter are designed. The simulation results presented have validated the theoretical claims. The experimental results which are similar to simulation results are evidence that the proposed topology is suitable for PV grid-tied systems. Also, the dynamic modeling of the inverter has been done to derive the plant transfer function. Then, the Proportional Resonant (PR) controller has been designed to ensure the flow of sinusoidal current into the grid with zero steady-state error and constant sinusoidal grid voltage irrespective of load change. The simulation and experimental results achieved high performance which makes this topology successful and promising for grid-tied PV systems

Going Beyond Relevance: Role of effort in Information Retrieval

The primary focus of Information Retrieval (IR) systems has been to optimize for Relevance. Existing approaches to rank documents or evaluate IR systems does not account for “user effort”. Currently, judges only determine whether the information provided in a given document would satisfy the underlying information need in a query. The current mechanism of obtaining relevance judgments does not account for time and effort that an end user must put forth to consume its content. While a judge may spend a lot of time assessing a document, an impatient user may not devote the same amount of time and effort to consume its content. This problem is exacerbated on smaller devices like mobile. While on mobile or tablets, with limited interaction, users may not put in too much effort in finding information. This thesis characterizes and incorporates effort in Information Retrieval. Comparison of explicit and implicit relevance judgments across several datasets reveals that certain documents are marked relevant by the judges but are of low utility to an end user. Experiments indicate that document-level effort features can reliably predict the mismatch between dwell time and judging time of documents. Explicit and preference-based judgments were collected to determine which factors associated with effort agreed the most with user satisfaction. The ability to locate relevant information or findability was found to be in highest agreement with preference judgments. Findability judgments were also gathered to study the association of different annotator, query or document related properties with effort judgments. We also investigate how can existing systems be optimized for relevance and effort. Finally, we investigate the role of effort on smaller devices with the help of cost-benefit models

Generating Query Suggestions to Support Task-Based Search

We address the problem of generating query suggestions to support users in completing their underlying tasks (which motivated them to search in the first place). Given an initial query, these query suggestions should provide a coverage of possible subtasks the user might be looking for. We propose a probabilistic modeling framework that obtains keyphrases from multiple sources and generates query suggestions from these keyphrases. Using the test suites of the TREC Tasks track, we evaluate and analyze each component of our model.Comment: Proceedings of the 40th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR '17), 201

Obstetric emergencies: preparedness among nurses for safe motherhood

Background: Obstetric emergencies may turn catastrophic in women’s as well as obstetrician’s life. In the event of real emergency, all prior preparations may fall deficient. Every little contribution towards safe confinement brings about large reductions in maternal mortality and morbidity.Methods: Cross-sectional questionnaire based study carried out on nurses involved in perinatal care of parturient conducted at the Dept of Obstetrics & Gynecology of PCMS & RC, Bhopal.Results: Total study participants were 36 (100% response rate). Majority (83%) were aware about the two leading causes of maternal mortality (PE, PPH). Twenty four (67%) knew the warning signs of eclampsia and 61% knew the signs of eclampsia but only 17% were aware of MgSO4 toxicity. Only 56% could correctly prepare the loading dose of MgSO4. All were aware about PPH; however only17% knew methergine as the drug for active management. Grossly wrong attitude noted only in 27% for PPH and 27% for severe PE. Overall preparedness for emergency was satisfactory in LR and PNC.Conclusions: Though the overall awareness for identifying emergencies (PE, PPH) was satisfactory, lacunae in awareness were noted about components of eclampsia, magnesium toxicity and drugs required for initial management of PE and PPH. Preparedness of nurses in labour room and postnatal ward was fairly good. Regular assessment of awareness & preparedness for obstetric emergencies would be desirable to optimize the overall delivery outcomes especially at peripheral rural centres where nurses are primarily involved in the care of labouring women

Parasitic Protozoans in Some Edible Freshwater Fishes of River Asan, District Morena

In the present thesis, an effort has been made to study the various species of Myxobolus in freshwater fishes. Total 695 fishes belonging to different genera and 8 species are investigated for this purpose. Nine species of Myxobolus have been described. Their incidence, Morphology, and taxonomy are studied and compared. An attempt has been made to study the pathological effects of parasites on different organs viz. skin, muscles and gills. Effect of parasites on the growth of fishes is also noticed. Infection in muscles is caused by Myxobolus cultus, Myxobolus dujardini, Myxobolus cycloid, Myxobolus oviforme, Myxobolus cognati, Myxobolus ellipsoideus, Myxobolus cerebralis. The infection in Muscles is reported in Channa striatus, Clarias batrachus, Heteropneustes fossilis, Labeo rohita, Catla catla, Cirrhinus mrigala and Wallago attu. Gills are infected by Myxobolus oviforme in Clarias batrachus. Myxosporidian infection is noticed in gill lamellae only. Skin and muscles are infected by Myxobolus oviforme in Clarias batrachus and the infection is reported in melanophores. Calcification is reported in gills only while necrosis is only noticed in the skin

Parasitic Protozoans in Some Edible Freshwater Fishes of River Asan, District Morena

In the present thesis, an effort has been made to study the various species of Myxobolus in freshwater fishes. Total 695 fishes belonging to different genera and 8 species are investigated for this purpose. Nine species of Myxobolus have been described. Their incidence, Morphology, and taxonomy are studied and compared. An attempt has been made to study the pathological effects of parasites on different organs viz. skin, muscles and gills. Effect of parasites on the growth of fishes is also noticed. Infection in muscles is caused by Myxobolus cultus, Myxobolus dujardini, Myxobolus cycloid, Myxobolus oviforme, Myxobolus cognati, Myxobolus ellipsoideus, Myxobolus cerebralis. The infection in Muscles is reported in Channa striatus, Clarias batrachus, Heteropneustes fossilis, Labeo rohita, Catla catla, Cirrhinus mrigala and Wallago attu. Gills are infected by Myxobolus oviforme in Clarias batrachus. Myxosporidian infection is noticed in gill lamellae only. Skin and muscles are infected by Myxobolus oviforme in Clarias batrachus and the infection is reported in melanophores. Calcification is reported in gills only while necrosis is only noticed in the skin

A descriptive study to assess the knowledge of coronavirus among nursing students, Sirmaur, Himachal Pradesh

Background: The coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by novel coronavirus and hence this pandemic has a great impact on the education system. Nursing students as part of the health team should know the coronavirus like other communicable diseases. Methods: A quantitative approach and cross-sectional survey research design used to assess the knowledge of Coronavirus among 145 nursing students of district Sirmaur selected through the convenient sampling technique. An online self-structured questionnaire used as a tool for data collection. Descriptive data analysis was done with SPSS (version 23).Results: The result of the study revealed that only 31.7% of students had good knowledge about COVID-19, and 68.3% had average knowledge. Conclusions: There is a need for intervention such as educational programs or pieces of training to educate about the pandemic and its prevention practices to undergraduate students to make our society more secure