68 research outputs found

    Optimizing Lead-free MASnBr3 Perovskite Solar Cells for High-Efficiency and Long-Term Stability Using Graphene and Advanced Interface Layers

    Get PDF
    Perovskite solar cells (PSCs) have garnered significant attention in the scientific community due to their rapid increase in performance. Inorganic perovskite devices have been noted for their high performance and long-term stability. This study introduces a device optimization process guided by modeling to produce high-efficiency PSCs using lead-free n-i-p methylammonium tin bromide (MASnBr3) materials. We have thoroughly examined the impact of both the absorber and interface layers on the optimized structure. Our approach utilized graphene as the interface layer between the hole transport and absorber layers. We employed zinc oxide (ZnO)/Al and 3C-SiC as interface layers between the absorber and electron transport layers. The optimization process involved adjusting the thicknesses of the absorber layer and interface layers and minimizing defect densities. Our proposed optimized device structure, ZnO/3C-SiC/MASnBr3/graphene/CuO/Au, demonstrates theoretical power conversion efficiencies of 31.97%, fill factors of 89.38%, a current density of 32.54 mA/cm2, a voltage of 1.112 V, and a quantum efficiency of 94%. This research underscores the ability of MASnBr3 as a nontoxic perovskite material for sustainable energy from renewable sources' applications

    A Model for Maintenance Planning and Process Quality Control Optimization Based on EWMA and CUSUM Control Charts

    Get PDF
    The performance of a production system is highly dependent on the smooth operation of various equipment and processes. Thus, reducing failures of the equipment and processes in a cost-effective manner improves overall performance; this is often achieved by carrying out maintenance and quality control policies. In this study, an integrated optimization method that addresses both maintenance strategies and quality control practices is proposed using an exponentially weighted moving average (EWMA) chart, in which both corrective and preventive maintenance policies are considered. The integrated model has been proposed to find optimal decision variables of both the process quality decision parameters and the optimal interval of preventive maintenance (i.e., Ns, Hs, L, λ, and t_PM) to result in overall optimal expected hourly total system costs. A case study is then utilized to investigate the impact of cost criteria on the proposed integrated model and to compare the proposed model with a model using the cumulative sum (CUSUM) control chart. The improved model outputs indicate that there is a reduction of 34.6% in the total expected costs compared with those of the other model using the CUSUM chart. Finally, an analysis of sensitivity to present the effectiveness of the model parameters and the main variables in the overall costs of the system is provided

    A New Association Analysis-Based Method for Enhancing Maintenance and Repair in Manufacturing

    Get PDF
    Maintenance and quality of products are absolutely crucial for any organization to succeed in the industrial and manufacturing engineering. Current research studies have confirmed the presence of a high correlation between these two factors, namely maintenance and quality of products, in industrial organizations. Nevertheless, no extensive research has been conducted in order to study the link between maintenance and the quality of products in manufacturing. In this paper, we conduct a study in this domain and examine the relationship patterns between maintenance and the quality of product using manufacturing data on maintenance and the product quality. Specifically, we employ association analysis and association rule mining with large and extensive sets of product quality, repair, and maintenance data. Our main objective is to discover interesting and non-trivial associations for feature failure resulting in the repair or maintenance of a product with unapproved quality. The results of evaluation are quite interesting. The resulting association rules with high values of confidence and lift suggest some essential associations between the product features and the failure; such findings have not been known and used before. This can help quality engineers and maintenance teams to enhance maintenance and repair operations and lower the overall cost of manufacturing

    A dual source fed eleven level switched capacitor multilevel inverter with voltage boosting capability

    Get PDF
    This work introduces an 11-level switched-capacitor multilevel inverter (SCMLI) designed for solar photo-voltaic (PV) applications, capitalizing on the growing popularity of multilevel inverters due to their superior power quality. With a 1.67-times boosting capability, the proposed SCMLI employs 10 switches, 2 DC supplies, and 2 capacitors to achieve an 11-level output voltage waveform. The topology requires only seven driver circuits, incorporating 2 bidirectional switches and 3 complementary pairs of switches. The proposed inverter has intrinsic capacitor self-balancing features since the capacitors are connected across the DC voltage source at different times throughout a basic cycle to charge the capacitors at a level of input voltage. A thorough comparison between the topology and recently developed SCMLI’s has been presented. The comparison demonstrates the effectiveness in terms of switches, capacitors, sources, efficiency, total standing voltage (TSV), and boosting capacity. To experimentally validate its performance, the suggested SCMLI undergoes testing using a frequency-based switching method. The topology exhibits low total harmonic distortion (THD) of 7.65% in its output voltage waveform and 0.89% in the output current waveform

    Egyptian Needs and the Water Resources Under the Agreements Among the Nile River Basin Countries

    Get PDF
    Abstract: Water is Egypt issue today, and its danger is increasing in the future years. Egypt is considered one of the poorest 35 countries in the world,its ownership of freshwater resources, where Egyptian citizen share in 1947year was reached about 2604 m 3 / year, it decreased over the years following that reached 860 m 3 / year in 2003, possibly the individual share will decrease to 582 m 3 / year in 2025, due to the available water resources for agriculture is limited, the future demand increasing for the purposes of horizontal and vertical expansion in cultivated area, the low efficiency of availability use of it, in addition to the obstacles in the traditional sources use, and as a result of the increase in population with demand for water is increased,and the available renewable water resources are constant, which led to increase the water problem in Egypt, Therefore, the study aimed to Identify the current available of Egyptian needs, water resources, individual share average of water, and identify the periods of abundance,scarcity and water poverty through the presentation of the various water agreements among the Nile River Basin countries, The study proved that total water needs reached about 69

    Longitudinal changes in peri-papillary retinal nerve fiber layer thickness in patients with unilateral branch retinal vein occlusion

    Get PDF
    Background: Associations between retinal venous occlusion (RVO), elevated intraocular pressure, and glaucoma have been reported. Further investigations into structural alterations in the fellow eyes of individuals with unilateral RVO have revealed that the peripapillary retinal nerve fiber layer is thinner than in healthy eyes, suggesting that there may be systemic risk factors common to both RVO and glaucoma. We aimed to evaluate changes in peripapillary retinal nerve fiber layer thickness (pRNFLT) among individuals with unilateral branch retinal vein occlusion (BRVO). Methods: This prospective observational study recruited 30 individuals (60 eyes) with newly diagnosed unilateral BRVO and macular edema, and a control group of 30 healthy individuals (30 eyes) with no abnormalities on fundus examination or concurrent systemic comorbidities. After baseline measurements, the participants were reassessed at 6, 12, and 24 months by measuring global and sectoral pRNFLT using spectral-domain optical coherence tomography. Results: The mean age and sex distributions were comparable between the patient and control groups (both P > 0.05). When compared to fellow eyes, global and sectoral pRNFLT in eyes with BRVO were significantly higher at baseline (all P < 0.05). Over time, pRNFLT decreased dramatically, and by the conclusion of the two-year follow-up, there was a significant reduction from baseline in the affected eyes (all P < 0.05). Likewise, affected eyes experienced a significant improvement in best-corrected distance visual acuity and central macular thickness over the two-year follow-up (both P Less than or equal to 0.001). Comparing the global and all-sector pRNFLT of fellow eyes in the patient group with those of normal eyes in the control group, there were no significant differences at any visit, except in the temporal sector, which revealed a significant reduction in pRNFLT at 24 months in the fellow eyes of patients with unilateral BRVO (P = 0.02).   Conclusions: Patients with unilateral BRVO experienced a significant reduction in pRNFLT in the affected eyes and, to a lesser extent, in the fellow eyes, compared with that of the control arm, suggesting that they are prone to retinal nerve fiber layer damage. The reduction in pRNFLT in the normal fellow eyes of patients with BRVO may be attributed to age or concurrent systemic comorbidities. Further studies with long follow-up periods are required to shed light on the etiology of functional and structural changes in both the retinal nerve fiber layer and ganglion cell complex in the normal and affected eyes of patients with unilateral BRVO

    Male Oxidative Stress Infertility (MOSI): Proposed Terminology and Clinical Practice Guidelines for Management of Idiopathic Male Infertility

    Get PDF
    Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm’s potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause

    Global, regional, and national burden of traumatic brain injury and spinal cord injury, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016.

    Get PDF
    Traumatic brain injury (TBI) and spinal cord injury (SCI) are increasingly recognised as global health priorities in view of the preventability of most injuries and the complex and expensive medical care they necessitate. We aimed to measure the incidence, prevalence, and years of life lived with disability (YLDs) for TBI and SCI from all causes of injury in every country, to describe how these measures have changed between 1990 and 2016, and to estimate the proportion of TBI and SCI cases caused by different types of injury. METHODS: We used results from the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016 to measure the global, regional, and national burden of TBI and SCI by age and sex. We measured the incidence and prevalence of all causes of injury requiring medical care in inpatient and outpatient records, literature studies, and survey data. By use of clinical record data, we estimated the proportion of each cause of injury that required medical care that would result in TBI or SCI being considered as the nature of injury. We used literature studies to establish standardised mortality ratios and applied differential equations to convert incidence to prevalence of long-term disability. Finally, we applied GBD disability weights to calculate YLDs. We used a Bayesian meta-regression tool for epidemiological modelling, used cause-specific mortality rates for non-fatal estimation, and adjusted our results for disability experienced with comorbid conditions. We also analysed results on the basis of the Socio-demographic Index, a compound measure of income per capita, education, and fertility. FINDINGS: In 2016, there were 27·08 million (95% uncertainty interval [UI] 24·30-30·30 million) new cases of TBI and 0·93 million (0·78-1·16 million) new cases of SCI, with age-standardised incidence rates of 369 (331-412) per 100 000 population for TBI and 13 (11-16) per 100 000 for SCI. In 2016, the number of prevalent cases of TBI was 55·50 million (53·40-57·62 million) and of SCI was 27·04 million (24·98-30·15 million). From 1990 to 2016, the age-standardised prevalence of TBI increased by 8·4% (95% UI 7·7 to 9·2), whereas that of SCI did not change significantly (-0·2% [-2·1 to 2·7]). Age-standardised incidence rates increased by 3·6% (1·8 to 5·5) for TBI, but did not change significantly for SCI (-3·6% [-7·4 to 4·0]). TBI caused 8·1 million (95% UI 6·0-10·4 million) YLDs and SCI caused 9·5 million (6·7-12·4 million) YLDs in 2016, corresponding to age-standardised rates of 111 (82-141) per 100 000 for TBI and 130 (90-170) per 100 000 for SCI. Falls and road injuries were the leading causes of new cases of TBI and SCI in most regions. INTERPRETATION: TBI and SCI constitute a considerable portion of the global injury burden and are caused primarily by falls and road injuries. The increase in incidence of TBI over time might continue in view of increases in population density, population ageing, and increasing use of motor vehicles, motorcycles, and bicycles. The number of individuals living with SCI is expected to increase in view of population growth, which is concerning because of the specialised care that people with SCI can require. Our study was limited by data sparsity in some regions, and it will be important to invest greater resources in collection of data for TBI and SCI to improve the accuracy of future assessments

    Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016

    Get PDF
    BACKGROUND: Measurement of changes in health across locations is useful to compare and contrast changing epidemiological patterns against health system performance and identify specific needs for resource allocation in research, policy development, and programme decision making. Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we drew from two widely used summary measures to monitor such changes in population health: disability-adjusted life-years (DALYs) and healthy life expectancy (HALE). We used these measures to track trends and benchmark progress compared with expected trends on the basis of the Socio-demographic Index (SDI). METHODS: We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2016. We calculated DALYs by summing years of life lost and years of life lived with disability for each location, age group, sex, and year. We estimated HALE using age-specific death rates and years of life lived with disability per capita. We explored how DALYs and HALE differed from expected trends when compared with the SDI: the geometric mean of income per person, educational attainment in the population older than age 15 years, and total fertility rate. FINDINGS: The highest globally observed HALE at birth for both women and men was in Singapore, at 75·2 years (95% uncertainty interval 71·9-78·6) for females and 72·0 years (68·8-75·1) for males. The lowest for females was in the Central African Republic (45·6 years [42·0-49·5]) and for males was in Lesotho (41·5 years [39·0-44·0]). From 1990 to 2016, global HALE increased by an average of 6·24 years (5·97-6·48) for both sexes combined. Global HALE increased by 6·04 years (5·74-6·27) for males and 6·49 years (6·08-6·77) for females, whereas HALE at age 65 years increased by 1·78 years (1·61-1·93) for males and 1·96 years (1·69-2·13) for females. Total global DALYs remained largely unchanged from 1990 to 2016 (-2·3% [-5·9 to 0·9]), with decreases in communicable, maternal, neonatal, and nutritional (CMNN) disease DALYs offset by increased DALYs due to non-communicable diseases (NCDs). The exemplars, calculated as the five lowest ratios of observed to expected age-standardised DALY rates in 2016, were Nicaragua, Costa Rica, the Maldives, Peru, and Israel. The leading three causes of DALYs globally were ischaemic heart disease, cerebrovascular disease, and lower respiratory infections, comprising 16·1% of all DALYs. Total DALYs and age-standardised DALY rates due to most CMNN causes decreased from 1990 to 2016. Conversely, the total DALY burden rose for most NCDs; however, age-standardised DALY rates due to NCDs declined globally. INTERPRETATION: At a global level, DALYs and HALE continue to show improvements. At the same time, we observe that many populations are facing growing functional health loss. Rising SDI was associated with increases in cumulative years of life lived with disability and decreases in CMNN DALYs offset by increased NCD DALYs. Relative compression of morbidity highlights the importance of continued health interventions, which has changed in most locations in pace with the gross domestic product per person, education, and family planning. The analysis of DALYs and HALE and their relationship to SDI represents a robust framework with which to benchmark location-specific health performance. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform health policies, health system improvement initiatives, targeted prevention efforts, and development assistance for health, including financial and research investments for all countries, regardless of their level of sociodemographic development. The presence of countries that substantially outperform others suggests the need for increased scrutiny for proven examples of best practices, which can help to extend gains, whereas the presence of underperforming countries suggests the need for devotion of extra attention to health systems that need more robust support. FUNDING: Bill & Melinda Gates Foundation

    Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.

    Get PDF
    The Global Burden of Diseases, Injuries and Risk Factors 2017 includes a comprehensive assessment of incidence, prevalence, and years lived with disability (YLDs) for 354 causes in 195 countries and territories from 1990 to 2017. Previous GBD studies have shown how the decline of mortality rates from 1990 to 2016 has led to an increase in life expectancy, an ageing global population, and an expansion of the non-fatal burden of disease and injury. These studies have also shown how a substantial portion of the world's population experiences non-fatal health loss with considerable heterogeneity among different causes, locations, ages, and sexes. Ongoing objectives of the GBD study include increasing the level of estimation detail, improving analytical strategies, and increasing the amount of high-quality data. METHODS: We estimated incidence and prevalence for 354 diseases and injuries and 3484 sequelae. We used an updated and extensive body of literature studies, survey data, surveillance data, inpatient admission records, outpatient visit records, and health insurance claims, and additionally used results from cause of death models to inform estimates using a total of 68 781 data sources. Newly available clinical data from India, Iran, Japan, Jordan, Nepal, China, Brazil, Norway, and Italy were incorporated, as well as updated claims data from the USA and new claims data from Taiwan (province of China) and Singapore. We used DisMod-MR 2.1, a Bayesian meta-regression tool, as the main method of estimation, ensuring consistency between rates of incidence, prevalence, remission, and cause of death for each condition. YLDs were estimated as the product of a prevalence estimate and a disability weight for health states of each mutually exclusive sequela, adjusted for comorbidity. We updated the Socio-demographic Index (SDI), a summary development indicator of income per capita, years of schooling, and total fertility rate. Additionally, we calculated differences between male and female YLDs to identify divergent trends across sexes. GBD 2017 complies with the Guidelines for Accurate and Transparent Health Estimates Reporting
    corecore