MODELING, DESIGN, AND IMPLEMENTATION OF HIGH GAIN POWER ELECTRONIC DC-DC CONVERTERS FOR NANOGRID APPLICATIONS

Nanogrids are nothing but power distribution systems that are based on renewable energy sources and are apt for low-power home applications. Nanogrids are considered to be the building cells of a Microgrid. Nanogrid is intended for feeding domestic loads (of the order of 100 W to 5 kW) from renewable energy sources such as wind farms, roof-top solar photovoltaic, biomass, and fuel cell, etc. Nonetheless, the voltages produced by these renewable energy sources are small and not sufficient enough to be utilized in all the applications. Hence, it is necessary to include high gain and high-efficiency DC-DC converters in the system. To interface the generators and the loads, power electronic converters are employed within a Nanogrid. The power system grid is also linked to the Nanogrid using these converters. The most fundamental characteristics of the high-gain DC-DC converters are high efficiency, high-voltage gain, and low voltage/current stress on switching components. A comprehensive literature review of various boosting methods is disseminated in this research work. After a detailed investigation, five new DC-DC power converter topologies have been designed and developed to achieve high gain factors with reduced switch ratings and low cost for use in Nanogrids. The proposed converters cannot only reduce voltage/current stresses across the switching components significantly but also achieve a higher voltage gain at moderate duty cycles with a lesser number of components. Moreover, the proposed converters are designed in such a way that they can maintain a continuous input current, and hence making them useful for power conversion in the battery, fuel cell, and solar PV applications. By using boosting technique five novel high voltage gain DC-DC converters are developed and presented in the dissertation, namely: 1. modified Switched Inductor Boost Converter (mSIBC) with reduced switch voltage stress, 2. Transformer-less Boost Converter (TBC) with reduced voltage stress, 3. Switched-Inductor based DC-DC Converter with reduced switch current stress, 4. Novel High Gain Active Switched Network-Based Converter, and 5. Double Stage Converter with low current stress for Nanogrid The detailed theoretical analysis of the voltage conversion ratio, parameter design, continuous and discontinuous conduction mode, and advantages are presented. In addition, a detailed comparative study of each converter topology is also given. The functionality of the proposed power converters is tested in real-time by developing Laboratory prototypes of the proposed converters and the theoretical analysis is validated by obtaining the experimental results. The proposed converter configurations are simulated in MATLAB as well, to verify the theoretical analysis. Simulation results of all the proposed converters are presented indicating clear evidence of the expected predictions in close proximity with experimental results

Association of depression with sexual function in women with history of recurrent pregnancy Loss:descriptive-correlational study in Tehran, Iran

Purpose: The present study aimed to investigate the relationship between depression and sexual function in women with recurrent pregnancy loss. Methods: In a cross-sectional correlational study, 130 consecutive patients with history of recurrent pregnancy loss were included who referred to Avicenna Fertility Center in Tehran, Iran during November 2018-February 2019. The outcomes were sexual dysfunction (Assessed with the Female Sexual Function Index) and depression (Evaluated with the Beck's Depression Inventory). The study data were analyzed by using Mann-Whitney and Kruskal-Wallis tests. Results: The study findings revealed that 40.8% of the participants suffered from some degrees of depression. The data analysis revealed that depression had a significant inverse correlation with sexual function and its domains (r = - 0.392, p < 0.001, R2= 0.15). The spouse' education level and economic status demonstrated a significant relationship with women's sexual function (p = 0.01, p = 0.033). A significant relationship was also detected between women's depression and economic status (p = 0.028). Conclusions: The study findings showed that women with RPL who had severe depression indicated lower score of sexual function. Since psychological and sexual problems are not reported to health care providers due to giving priority to fertility issues or considering such issues as taboos, the assessment of sexual and mental health needs to be part of the consultation in women with history of RPL, whether the patient seeks help for depression and sexual dysfunction or not

Modelling, analysis, and implementation of a switched-inductor based DC/DC converter with reduced switch current stress

This paper proposes a technique for switch current stress reduction in a Switched Inductor DC-DC Boost Converter (SIBC). The proposed technique comes up with a low-cost design, high voltage conversion ratio with a less duty cycle value, and lower current stress without increasing the component count. This topology is basically a transformer-less design where one diode of the traditional switched inductor configuration has been replaced with a switch, which is in parallel with the existing switch, resulting in a design that can incorporate active switches with a low current rating, since the total input current is equally shared by them. The detailed modes of operation in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) and steady-state analysis, the non-idealities' effect on voltage gain, design approach, and a comparative study with other DC-DC converters for some significant performance characteristics are provided. The experimental validations for the performance and working of the 500 W designed prototype are presented.This publication was made possible by Qatar University-Marubeni Concept to Prototype Development Research grant no. M-CTP-CENG-2020-2 from the Qatar University.Scopu

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

A Single Inductor, Single Switch High Gain DC-DC Boost Converter

Switched capacitor-based voltage multiplier cell (VMC) is generally employed to increase the output voltage of the dc-dc converter. The proposed converter is a new high gain dc-dc boost converter which utilizes only a single switch and a single inductor with switched capacitors to increase the voltage at the output. The other good features of this converter are high reduced voltage stress on the switch and capacitors. The Mathematical analysis is done in continuous current mode using ideal assumptions. The comparative assessment of the proposed converter is carried out with other recently published boost converters. The simulation is carried out using PLECS software tool which validates the working of the converter and theoretical results

Double stage converter with low current stress for low to high voltage conversion in nanogrid

A low to high voltage conversion technique has been proposed in this paper using double stages of switched inductors for nanogrid applications. The proposed converter topology utilizes fewer components, achieves high voltage gain at a small value duty ratio, and has high efficiency. Moreover, the proposed converter provides a reduced switch current stress to obtain a stable constant boosted DC voltage. Therefore, it requires low-current rating switches and hence leads to cost reduction. Additionally, the load and the source end are connected to the same ground. The principle of operation, theoretical waveforms in Continuous Conduction Mode (CCM), and Discontinuous Conduction Mode (DCM) with steady-state analysis are discussed. A detailed discussion about the effect of non-idealities on the high voltage conversion, the design of components, and a comparison of the performance characteristics such as the number of components, Voltage Gain in CCM, switch current stress, normalized switch voltage stress, and efficiency of the proposed converter topology with other converters are presented. The experimental results of the 500W laboratory prototype are also shown to validate the operation of the proposed converter.This publication was made possible by Qatar University- Marubeni Concept to Prototype Development Research grant # [M-CTP-CENG-2020-2] from the Qatar University. The statements made herein are solely the responsibility of the authors. Open Access funding is provided by the Qatar National Library.Scopu

A Novel Modified Switched Inductor Boost Converter with Reduced Switch Voltage Stress

Recently, switched inductor (SI) and switched capacitor techniques in dc-dc converter are recommended to achieve high voltage by using the principle of parallel charging and series discharging of reactive elements. It is noteworthy that four diodes, one high-voltage rating switch, and two inductors are required to design classical SI boost converter (SIBC). Moreover, in classical SIBC, the switch voltage stress is equal to the output voltage. In this article, modified SIBC (mSIBC) is proposed with reduced voltage stress across active switches. The proposed mSIBC configuration in this article is transformerless and simply derived by replacing the one diode of the classical SI structure with an active switch. As a result, mSIBC required low-voltage rating active switches, since the total output voltage is shared into two active switches. Moreover, the proposed mSIBC is low in cost, provides higher efficiency, and requires the same number of components compared with the classical SIBC. The continuous conduction mode and discontinuous conduction mode analysis, the effect of nonidealities on voltage gain, design methodology, and comparison are presented in detail. The operation and performance of the designed 500-W mSIBC are experimentally validated under different perturbations.Manuscript received July 14, 2019; revised October 15, 2019 and December 13, 2019; accepted January 3, 2020. Date of publication February 5, 2020; date of current version October 30, 2020. This work was supported by Qatar University High Impact under Grant QUHI-CENG-19/20-2, from the Qatar University. The publication charges are funded by the Qatar National Library. The statements made herein are solely the responsibility of the authors. (Corresponding author: Atif Iqbal.) S. Sadaf, M. Meraj, A. Iqbal, and N. Al-Emadi are with the Department of Electrical Engineering, Qatar University, Doha 2713, Qatar (e-mail: [email protected]; [email protected]; [email protected]; [email protected]).Scopu

A Novel Modified Switched Inductor Boost Converter with Reduced Switch Voltage Stress

DC-DC power converters are necessary to step-up the voltage or current with high conversion ratio for many applications e.g. photovoltaic and fuel cell energy conversion, uninterruptible power supply, DC microgrid, automobile, high intensity discharged lamp ballast, hybrid vehicle, etc. in order to use low voltage sources. In this project, a modified SIBC (mSIBC) is proposed with reduced voltage stress across active switches. The proposed mSIBC configuration is transformer-less and simply derived by replacing one diode of the classical switched inductor structure with an active switch. As a result, mSIBC required low voltage rating active switches, as the total output voltage is shared between two active switches. Moreover, the proposed mSIBC is low in cost, provides higher efficiency and required the same number of components compared to the classical SIBC. The experimental results are presented which validated the theoretical analysis and functionality, and the efficiency of the designed converter is 97.17%. The proposed mSIBC converter provides higher voltage conversion ratio compared to classical converters e.g. boost, buck-boost, cuk, and SEPIC. The newly designed configurations will aid the intermediate power stage between the renewable sources and utility grid or high voltage DC or AC load. Since, the total output voltage is distributed among the two active switches, low voltage rating switches can be employed to design the power circuit of the proposed converter. The classical boost converter or recently proposed switched inductor based boost converter can be replaced by the proposed mSIBC converter in real-time applications such as DC microgrid, DC-DC charger, battery backup system, UPS, EV, an electric utility grid. The proposed power circuitry is Cost effective, Compact in size, easily diagnostic, highly efficient and reliable

New High Gain 2LC-Y Multilevel-Boost-Converter (2LC-Y MBC) Topologies for Renewable Energy Conversion: Members of X-Y Converter Family

This paper presents a new high gain 2LC-Y Multilevel-Boost-Converter or 2LC-Y MBC topologies for renewable energy conversion. Four new topologies 2LC-L MBC, 2LC-2L MBC, 2LC-2LC MBC, and 2LC-2LCm MBC are developed by combination of the voltage multiplier characteristics and the traditional 2LC-Y topologies of XY family (2LC-L, 2LC-2L, 2LC-2LC, and 2LC-2LCm) to achieve high voltage gain. These topologies are beneficial when used in applications where low to high voltage conversion is required, which makes it suitable for renewable energy applications like photovoltaic systems, fuel-cell system, hybrid vehicle, HVDC, and DC drives etc. Additionally, a stack of multiple capacitors present at the output side makes the proposed topologies highly suitable for utility grid using multilevel inverter (MLI). The operating principle of proposed 2LC-2LCm MBC topology is explained in detail and voltage gain analysis of the proposed converters is presented. Moreover, all the proposed topologies are compared with each others in terms of voltage gain. The simulation results validated the operation of the proposed converter and perfectly matching with the theoretical analysis. - 2019 IEEE.ACKNOWLEDGMENT This publication was made possible by High Impact grant # [QUHI-CENG-19/20-2] from the Qatar University. The statements made herein are solely the responsibility of the authors.Scopu