Performance analysis of real-time PSO tuned PI controller for regulating voltage and frequency in an AC microgrid

In this study, a control strategy based on the self-tuning method and synchronous reference frame (SRF) with PI regulator is proposed to achieve optimum quality of power in an autonomous micro grid (MG). The MGS is based on multiple distributed generation (DG) connected with 120 kV power grid. The proposed system is first simulated with fixed gain values for PI controller which are not optimal for sudden changes in the system i.e. transition of MG to islanding mode, load variations. So, the particle swarm optimization (PSO) has been utilized for tuning of PI controller parameters which ensure flexible performance and superior quality of power. The principal parameters considered in this study are, regulation of voltage and frequency, steady-state and dynamic response and harmonic distortion, mainly when microgrid is islanded. The performance of PI and PI-PSO is compared in this study by simulating AC microgrid in the MATLAB/Simulink environment. Summarized results of the system are provided to authenticate viability of proposed arrangement. The proposed controller performs intelligently while regulating voltage and frequency of the MGS and utility system.

Design of a charge controller circuit with Maximum Power Point Tracker (MPPT) for Photovoltaic system

This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering, 2012.Cataloged from PDF version of thesis report.Includes bibliographical references (page 63).This thesis, aim to design and simulation of a simple but effective charge controller with maximum power point tracker for photovoltaic system. It provides theoretical studies of photovoltaic systems and modeling techniques using equivalent electric circuits. As, the system employs the maximum power point tracker (MPPT), it is consists of various MPPT algorithms and control methods. P-Spice and MATLAB simulations verify the DC-DC converter design and hardware implementation. The results validate that MPPT can significantly increase the efficiency and the performance of PV.Rahman, ShusmitaOni, Nadia SultanaQuazi Abdullah Ibn MasudB. Electrical and Electronic Engineerin

Allocation of distributed generation and battery switching stations for electric vehicle using whale optimiser algorithm

With the increasing demand for electrical vehicles (EVs) in the existing distribution system due to road traffic sustainability, fuel costs reduction, and environmental improvement by the promotion of low carbons in transportation, system planners need to minimise energy losses and improve voltage profile of the grid. Few studies resolved these issues via optimum placement of distributed generation (DG) and battery switching station (BSS) units in distribution system; however, these techniques considered only active power loss minimisation with various methodological limitations. Therefore, a new application of whale optimiser algorithm (WOA) is proposed to solve these limitations. The simultaneous placement based approach of the units has been adopted to minimise active and reactive energy losses of 33- and 69-bus distribution systems. System performance has been analyzed based on multiple technical criteria, such as system loading factor, voltage profile improvement, and active and reactive power loss reduction indices. The results of WOA have been proven to be superior to those of artificial bee colony and gravitational search algorithms. Therefore, the proposed methodology can guide energy planners in determining optimal allocation of multiple DG and BSS units in their systems,; in addition to the expected energy loss reduction within the system, BSS, and DG planning and operational constraints

Teledentistry: Limitation and Challenges

Dentistry is the top listed most risky jobs in this pandemic Covid 19 situation, as dentist contain close face-to-face contact with the patients which increase the potential transmission of the (SARS)-CoV-2 virus from human to human through direct contact via oro-pharyngeal droplets and indirect contacts with fomites where dental professionals are highly vulnerable to get infected from the coronavirus. Thus, dental practice has mostly been suspended during this period. Teledentistry introduces a novel solution to resume dental practice by providing dental treatment, guidance, and education through teleconsultation, telediagnosis and telemonitoring through Information Technology (IT) instead of direct contact with patients. But there are some major challenges like lack of government initiatives, compensation strategy, legal issues, technical base, co-ordination among doctors, along with patients’ co-operation and limitations in telediagnosis. This technical note highlighted these limitations and challenges to make a concern to the dentist as at least teledentistry can accompaniment the existing threaten dental system during this living pandemic

Women’s Preferences for Maternal Healthcare Services in Bangladesh: Evidence from a Discrete Choice Experiment

Despite substantial improvements in several maternal health indicators, childbearing and birthing remain a dangerous experience for many women in Bangladesh. This study assessed the relative importance of maternal healthcare service characteristics to Bangladeshi women when choosing a health facility to deliver their babies. The study used a mixed-methods approach. Qualitative methods (expert interviews, focus group discussions) were initially employed to identify and develop the characteristics which most influence a women’s decision making when selecting a maternal health service facility. A discrete choice experiment (DCE) was then constructed to elicit women’s preferences. Women were shown choice scenarios representing hypothetical health facilities with nine attributes outlined. The women were then asked to rank the attributes they considered most important in the delivery of their future babies. A Hierarchical Bayes method was used to measure mean utility parameters. A total of 601 women completed the DCE survey. The model demonstrated significant predictive strength for actual facility choice for maternal health services. The most important attributes were the following: consistent access to a female doctor, the availability of branded drugs, respectful provider attitudes, a continuum of maternal healthcare including the availability of a c-section delivery and lower waiting times. Attended maternal healthcare utilisation rates are low despite the access to primary healthcare facilities. Further implementation of quality improvements in maternal healthcare facilities should be prioritised

Where backyard poultry raisers seek care for sick poultry: implications for avian influenza prevention in Bangladesh

Abstract Background In Bangladesh, backyard poultry raisers lack awareness of avian influenza and infrequently follow government recommendations for its prevention. Identifying where poultry raisers seek care for their ill poultry might help the government better plan how to disseminate avian influenza prevention and control recommendations. Methods In order to identify where backyard poultry raisers seek care for their ill poultry, we conducted in-depth and informal interviews: 70 with backyard poultry raisers and six with local poultry healthcare providers in two villages, and five with government veterinary professionals at the sub-district and union levels in two districts during June–August 2009. Results Most (86% [60/70]) raisers sought care for their backyard poultry locally, 14% used home remedies only and none sought care from government veterinary professionals. The local poultry care providers provided advice and medications (n = 6). Four local care providers had shops in the village market where raisers sought healthcare for their poultry and the remaining two visited rural households to provide poultry healthcare services. Five of the six local care providers did not have formal training in veterinary medicine. Local care providers either did not know about avian influenza or considered avian influenza to be a disease common among commercial but not backyard poultry. The government professionals had degrees in veterinary medicine and experience with avian influenza and its prevention. They had their offices at the sub-district or union level and lacked staffing to reach the backyard raisers at the village level. Conclusions The local poultry care providers provided front line healthcare to backyard poultry in villages and were a potential source of information for the rural raisers. Integration of these local poultry care providers in the government’s avian influenza control programs is a potentially useful approach to increase poultry raisers’ and local poultry care providers’ awareness about avian influenza

Contaminated Turmeric Is a Potential Source of Lead Exposure for Children in Rural Bangladesh

Background. During the conduct of a cohort study intended to study the associations between mixed metal exposures and child health outcomes, we found that 78% of 309 children aged 20–40 months evaluated in the Munshiganj District of Bangladesh had blood lead concentrations ≥5 µg/dL and 27% had concentrations ≥10 µg/dL. Hypothesis. Environmental sources such as spices (e.g., turmeric, which has already faced recalls in Bangladesh due to high lead levels) may be a potential route of lead exposure. Methods. We conducted visits to the homes of 28 children randomly selected from among high and low blood lead concentration groups. During the visits, we administered a structured questionnaire and obtained soil, dust, rice, and spice samples. We obtained water samples from community water sources, as well as environmental samples from neighborhood businesses. Results. Lead concentrations in many turmeric samples were elevated, with lead concentrations as high as 483 ppm. Analyses showed high bioaccessibility of lead. Conclusions. Contamination of turmeric powder is a potentially important source of lead exposure in this population

Cost of illness for severe and non-severe diarrhea borne by households in a low-income urban community of Bangladesh: A cross-sectional study

The illness cost borne by households, known as out-of-pocket expenditure, was 74% of the total health expenditure in Bangladesh in 2017. Calculating economic burden of diarrhea of low-income urban community is important to identify potential cost savings strategies and prioritize policy decision to improve the quality of life of this population. This study aimed to estimate cost of illness and monthly percent expenditure borne by households due diarrhea in a low-income urban settlement of Dhaka, Bangladesh. We conducted this study in East Arichpur area of Tongi township in Dhaka, Bangladesh from September 17, 2015 to July 26, 2016. We used the World Health Organization (WHO) definition of three or more loose stool in 24 hours to enroll patients and enrolled 106 severe patients and 158 non-severe patients from Tongi General Hospital, local pharmacy and study community. The team enrolled patients between the first to third day of the illness (≤ 72 hours) and continued daily follow-up by phone until recovery. We considered direct and indirect costs to calculate cost-per-episode. We applied the published incidence rate to estimate the annual cost of diarrhea. The estimated average cost of illness for patient with severe diarrhea was US$27.39 [95$ 6.36 [95% CI: 5.19, 7.55] (499 BDT), 4% of the average monthly income of households. A single diarrheal episode substantially affects financial condition of low-income urban community residents: a severe episode can cost almost equivalent to 4.35 days (17%) and a non-severe episode can cost almost equivalent to 1 day (4%) of household’s income. Preventing diarrhea preserves health and supports financial livelihoods

Biosynthesis of silver nanoparticles from Cymbopogon citratus leaf extract and evaluation of their antimicrobial properties

Background: Silver nanoparticles (AgNPs) are toxic to microorganisms and can potentially kill multidrug-resistant bacteria. Nanoparticles can be synthesized in many ways, such as physical or chemical methods. Recently, it has been found that plant molecules can perform the same reduction reactions necessary for the production of nanoparticles but in a much more efficient way. Results: Here, green chemistry was employed to synthesize AgNPs using leaf extracts of Cymbopogon citratus. The effects of different parameters such as temperature, pH, and the volume of plant extract were also tested using their absorbance pattern at different wavelengths. The Surface Plasmon Resonance (SPR) changed with the changes in parameters. Changes in temperature from 20 °C to 60 °C have changed the highest absorbance from 0.972 to 3.893 with an SPR of 470 nm. At higher pH (11.1), the particles become highly unstable and have irregular shapes and sizes. The peak shifts to the right at a lower pH level (3.97), indicating a smaller but unstable compound. We have also investigated the effect of the volume of plant extracts on the reaction time. The sample with the highest amount of plant extract showed the most absorbance with a value of 0.963 at λmax, calculated to be 470 nm. The total formation of the AgNPs was observed visually with a color change from yellow to brownish-black. UV-visible spectroscopy was used to monitor the quantitative formation of AgNPs, showing a signature peak in absorbance between 400 and 500 nm. We have estimated the size of the nanoparticles as 47 nm by comparing the experimental data with the theoretical value using Mieplot. The biosynthesized AgNPs showed enhanced antibacterial activity against several multidrug-resistant bacteria, determined based on the minimal inhibitory concentration and zone of inhibition. Conclusion: The findings of this study indicate that an aqueous extract of C. citratus can synthesize AgNPs when silver nitrate is used as a precursor, and AgNPs act as antimicrobial property enhancers, which can be used to treat antibiotic-resistant bacteria. Hence, mass production and green synthesis of AgNPs from C. citratus will be able to increase the overall health of the general population. Moreover, it will enormously reduce the costs for drug development and provide employment options in the remotely located source areas. Finally, our findings will influence further studies in this field to better understand the properties and applications of AgNPs and ultimately contribute to improving planetary health by increasing immunity with high biocompatibility and less drug toxicity