Performance And Degradation Evaluation Of Grid-Connected Photovoltaic Systems At UTeM

Four grid-connected solar Photovoltaic (PV) systems were installed at Universiti Teknikal Malaysia Melaka (UTeM), namely Thin-Film (TF), Heterojunction with intrinsic thin layer (HIT), Poly crystalline, and Mono crystalline with the total capacity of 24 kWp since October 2013. Hence, it is important to evaluate the performance and the degradation of UTeM’s PV systems. In this regard, this research aims to evaluate the performance and the degradation of three of the four grid- connected PV systems located at UTeM, Melaka. The analysis presented in this study consists of the data recorded at 5 – minute intervals between January 2014 and December 2015. Meteorological parameters such as solar radiation and ambient temperature, module temperature, and solar generation were obtained from research laboratory of solar PV systems, smart grids, UTeM. The annual performance of the PV systems had been evaluated in terms of capacity factor, availability factor, reference yield, array yield, final yield, performance ratio, system losses, and array capture losses. The annual degradation rates of the PV systems were calculated using Power-Irradiance (P-G) technique. The average performance ratio of Thin-Film PV system for 2014 was 93.6% and 89.2% in 2015, while the average performance ratio of HIT PV system in 2014 was 85% and 82.3% in 2015, and the average performance ratio of Mono crystalline PV system in 2014 was 81.3% and 78.7% in 2015. The average degradation rates for two years of operation of Thin-Film, HIT, and Mono crystalline PV systems were 5.32%, 5.1%, and 3.65%, respectively. This study provides the insight for the system installer and investor in relation to the performance and degradation of various types of PV module technologies installed under Malaysia environment

Investigating the Impact of Partial Shading on Photovoltaic Panels and Enhancing their Efficiency using the Python

This research project focuses on investigating the impact of partial shading on photovoltaic (PV) panels and proposes methods to enhance their efficiency using Python programming. Partial shading can significantly reduce the performance of PV panels by creating imbalances in current and voltage outputs. By leveraging Python's computational capabilities, this study aims to develop simulation models and algorithms that accurately capture the behavior of shaded PV panels. The objectives of this research include building a comprehensive understanding of partial shading effects, developing a Python-based simulation framework, analyzing the impact of different shading patterns on PV panel efficiency, investigating novel techniques to enhance efficiency using Python, and evaluating proposed approaches through simulations and experimental validation. Through this investigation, we aim to contribute to the development of improved strategies for the design and operation of PV systems. By mitigating the negative effects of shading and enhancing PV panel efficiency, we can further promote the adoption of sustainable solar energy solutions. The outcomes of this research have the potential to advance the field of solar energy and facilitate a greener and cleaner future. Also, this paper aims to investigate the impact of partial shading on photovoltaic (PV) panels and explores methods to enhance their efficiency using Python. Partial shading can significantly reduce the overall output of PV systems, leading to suboptimal performance. By analyzing shading patterns and implementing intelligent algorithms, we can optimize PV panel configuration and improve their efficiency. In this study, the Python programming language will be utilized to develop simulation models, perform data analysis, and propose solutions for increasing the efficiency of shaded PV panels

Modelling Of Malaysian Reference Networks For Photovoltaic And Battery Energy Storage Systems Integration Studies

The thesis aims to develop and model six optimal Malaysian Medium Voltage (MV) Reference Networks (RNs) for the investigation of network performance under various future development scenarios. These include the integration of Photovoltaic (PV) system and Battery Energy Storage System (BESS) into the six MV RNs. The integration of PV system into the Malaysian MV distribution network is seen as one of the promising options to reduce carbon footprints for a low-carbon future. However, the integration of PV system into the existing MV distribution networks could cause reverse power flow problem. This reverse power flow may result in the increase of total network losses, voltage rise, and thermal violation of network components. Hence, one of the objectives of this thesis is to quantify the impact of PV integration with different PV locations, PV variability profiles, time resolution of PV profiles, and PV penetration levels on the optimal Malaysian MV RNs. In addition, the integration of PV system comes with other challenges such as PV output fluctuation, mismatch between PV generation and load demand, and network overvoltage. These issues will affect the power quality and the performance of the Malaysian MV distribution network. Therefore, this thesis also aims to identify the possible applications of BESS that could be used together with PV system to mitigate the potential network issues. The results on the optimal MV RNs show that the RNs with 11kV feeders have lower network losses as compared to the RNs with 33 and 11kV feeders. In addition, the losses in the rural RNs are higher than the urban and sub-urban RNs. The results also show that the utilization of optimal cables and transformers can reduce the network losses of between 3.52% to 19.22%. This translates into the increase of profit to the utility company of between RM 29 to RM 59884 per annum for the six RNs. Furthermore, the findings suggest that the total network losses are reduced between 3 to 7 times when the PV system is located at the end of 11kV feeder for the six RNs. The simulation results for PV variability study show that rural RNs with longer feeder need the highest number of voltage step changes (around 7300 annually) to maintain the voltage magnitude within the acceptable range. In addition, the time resolution case study suggests that one-minute interval PV generation profile is the most appropriate time resolution that could be used to analyze the MV total network losses for the urban, sub-urban, and rural RNs. The findings also emphasized the fact that once the PV penetration level threshold was achieved, the total network losses, voltage rise, and thermal violation of transformers will begin to increase. Finally, the BESS simulation results show the ability of lithium-ion BESS models to reduce the network maximum demand of between 4.84% to 52.71%. The BESS also helps to mitigate the issues which are caused by PV system integration through power output smoothening, demand following, and alleviating overvoltage problem

Performance Evaluation Of Various Solar Photovoltaic Module Technologies Under Tropical Climate Conditions At Melaka, Malaysia

The system performance of a grid-connected solar photovoltaic system is one of the most important parameters to monitor the health of the system. This study aims to evaluate the performance of three (3) PV module technologies, namely Thin-Film (TF), Heterojunction with Intrinsic Thin layer (HIT) and monocrystalline which are installed at Universiti Teknikal Malaysia Melaka (UTeM) under Malaysia tropical climate conditions. Actual annual solar resources and PV system’s energy output were recorded for two (2) consecutive years, i.e., 2014-2015 using the weather station and solar monitoring system installed in the laboratory. The annual average final yield of the PV systems ranged from 1452-1579.5 kWh/kWp/year. The average annual performance ratio of the 3 PV systems ranged from 80-91.4% while the average annual capacity factor of the 3 PV systems ranged from 16.5-18%. The average annual system losses of the 3 PV systems ranged from 154.46-302.15 kWh/kWp while the average annual array capture losses of the 3 PV systems ranged from -6.36-59.71 kWh/kWp. Outdoor assessment shows that the thin-film PV system had the highest performance ratio and capacity factor. Furthermore, the thin-film PV system produced the lowest system losses and array capture losses, compared to HIT and monocrystalline PV system

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Ki-67 expression as an indicator of invasiveness in patients with breast cancer

Background: Tumor markers have a key role in guiding breast cancer management protocols and predicting prognosis. Objective: The aim of the study is to explore the role of Ki-67 expression in breast cancer and correlate it to well-known indicators of invasiveness such as age, tumor size, grade, hormonal receptors, and lymph nodes involvement. Materials and Methods: This retrospective study was conducted on (214) patients who were newly diagnosed with breast cancer and referred to Azadi Teaching Hospital/Duhok-Iraq, from November 1st, 2016, to October 31st, 2017. Data regarding patient's demographics, tumor size, histological type and grade, nuclear grade, and lymph node involvement were obtained from medical records. Patients underwent either mastectomy with axillary lymph node dissection or breast conservation surgery. Collected specimens were sent for histopathological examination and immunohistochemistry assessments of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), and Ki67 expressions. Results: Our study showed that histological grade, nuclear grade, mitotic index, and HER2 status were positively correlated to Ki67 index (P < 0.05). Furthermore, ER and PR status showed a negative correlation to Ki67 index (P < 0.05). Age, tumor size, and the number of lymph nodes involved displayed no significant correlation to Ki67 level (P = 0.080, 0.738, and 0.888), respectively. Conclusion: Results of this study confirmed that Ki67 index are significantly correlated with tumor grade, ER, PR, and HER2 status. However, Ki67 expression association with other clinic-pathological parameters such as age, tumor size, or lymph node involvement is not recognized and requires further studies

Fluid dynamic and acoustic optimization methodology of a formula-student race car engine exhaust system using multilevel numerical CFD models

In this work a multilevel CFD analysis have been applied for the design of an engine exhaust system include manifold and muffler with improved characteristics of noise reduction and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model and 3D tools. Once the best configuration has been defined, the 1D-3D approach has been adopted to confirm the prediction carried out by means of the simplified approach, studying also the impact of the new configuration on the engine performances

Properties of Modified Warm-Mix Asphalt Mixtures Containing Different Percentages of Reclaimed Asphalt Pavement

The Rapid reduction of energy resources and the escalated effects of global warming have created a strong motivation to find some new techniques in the field of paving construction. Adopting new technologies, such as warm-mix asphalt (WMA) or the recycling process of asphalt can be very helpful for the economy and have a significant impact on the environmental footprint. Thus, this research aimed to study the mechanical and durable characteristics of modified WMA mixtures using (1.0%, 1.5%, and 2.0%) Sasobit REDUX®, (0.3%, 0.4%, and 0.5%) Aspha-Min®, and (0.07%, 0.1%, and 0.125) ZycoTherm® additives corresponding to three percentages of reclaimed asphalt pavement (RAP) (20%, 40%, and 60%). Three mixing temperatures have been conducted in this study to generate WMA mixtures at (135 °C, 125 °C, and 115 °C) corresponding to three compacting temperatures (125 °C, 115 °C, and 105 °C). The mechanical properties of the developed WMA mixtures have been evaluated using the Superpave volumetric properties (air voids, voids filled with asphalt, and voids in mineral aggregate), while the durable properties have been investigated using the resilient modulus test (MR) at 25 °C, resilient modulus ratio (RMR), and Hamburg wheel-track test in terms of permanent deformation, moisture susceptibility, and rutting resistance. To make the WMA mixtures accept high quantities of RAP (>25%), an insignificant increase in the amounts of WMA additives was needed to produce mixtures carrying sustainability labels. Results indicated that all the used additives had pushed the WMA mixtures to achieve considerable mechanical properties, whereas the best properties for the WMA mixtures containing 0%, 20%, 40%, and 60% of RAP have been achieved by mixing with (1.0% Sasobit REDUX® @ 125 °C), (1.0% Sasobit REDUX® or 0.3% Aspha-Min® @ 135 °C), (1.5% Sasobit REDUX® @ 125 °C), and (2.0% Sasobit REDUX® or 0.5% Aspha-Min® @ 135 °C), respectively. On another hand, the best durable properties have been achieved by mixing the mentioned WMA mixtures containing 0%, 20%, 40%, and 60% of RAP with 0.07%, 0.07%, 0.1%, and 0.125% of ZycoTherm® at 153 °C, respectively. Using such additives in the recycled WMA mixtures made it possible to activate waste recycling in the paving industry

Pancreatic surgery outcomes: multicentre prospective snapshot study in 67 countries

Background: Pancreatic surgery remains associated with high morbidity rates. Although postoperative mortality appears to have improved with specialization, the outcomes reported in the literature reflect the activity of highly specialized centres. The aim of this study was to evaluate the outcomes following pancreatic surgery worldwide.Methods: This was an international, prospective, multicentre, cross-sectional snapshot study of consecutive patients undergoing pancreatic operations worldwide in a 3-month interval in 2021. The primary outcome was postoperative mortality within 90 days of surgery. Multivariable logistic regression was used to explore relationships with Human Development Index (HDI) and other parameters.Results: A total of 4223 patients from 67 countries were analysed. A complication of any severity was detected in 68.7 percent of patients (2901 of 4223). Major complication rates (Clavien-Dindo grade at least IIIa) were 24, 18, and 27 percent, and mortality rates were 10, 5, and 5 per cent in low-to-middle-, high-, and very high-HDI countries respectively. The 90-day postoperative mortality rate was 5.4 per cent (229 of 4223) overall, but was significantly higher in the low-to-middle-HDI group (adjusted OR 2.88, 95 per cent c.i. 1.80 to 4.48). The overall failure-to-rescue rate was 21 percent; however, it was 41 per cent in low-to-middle-compared with 19 per cent in very high-HDI countries.Conclusion: Excess mortality in low-to-middle-HDI countries could be attributable to failure to rescue of patients from severe complications. The authors call for a collaborative response from international and regional associations of pancreatic surgeons to address management related to death from postoperative complications to tackle the global disparities in the outcomes of pancreatic surgery (NCT04652271; ISRCTN95140761)