7 research outputs found
A Multiobjective Artificial-Hummingbird-Algorithm-Based Framework for Optimal Reactive Power Dispatch Considering Renewable Energy Sources
No full textThis paper proposes a new artificial hummingbird algorithm (AHA)-based framework to investigate the optimal reactive power dispatch (ORPD) problem which is a critical problem in the capacity of power systems. This paper aims to improve the performance of power systems by minimizing two distinct objective functions namely active power loss in the transmission network and total voltage deviation at the load buses subjected to various constraints within multiobjective framework. The proposed AHA-based framework maps the inherent flight and foraging capabilities exhibited by hummingbirds in nature to determine the best settings for the control variables (i.e., voltages at generation buses, the tap positions of on-load tap-changing transformers (OLTCs) and the size of switchable shunt VAR compensators) to minimize the overall objective functions. A multiobjective optimal reactive power dispatch framework (MO-ORPD) considering renewable energy sources (RES) and load uncertainties is also proposed to minimize the individual objectives simultaneously. The competency and robustness of the proposed AHA-based framework is validated and tested on IEEE 14 bus and IEEE 39 bus test systems to solve the ORPD problem. Eventually, the results are compared with other well-known optimization techniques in the literature. Box plots and statistical tests using SPSS are performed and validated to justify the effectiveness of the proposed framework
Hybrid Weighted Least Square Multi-Verse Optimizer (WLS–MVO) Framework for Real-Time Estimation of Harmonics in Non-Linear Loads
No full textThe electric power quality has become a serious concern for electric utilities and end users owing to its undesirable effects on system capabilities and performance. Harmonic levels on power systems have been pronounced to a greater extent with the continuous growth in the application of solid-state and reactive power compensatory devices. Harmonics are the key constituents that are mainly responsible for power quality deterioration. Power system harmonics need to be correctly estimated and filtered to increase power quality. This research work focuses on accurate estimation of power system harmonics with the proposed hybrid weighted least-square multi-verse optimizer (WLS–MVO) based framework. Multi-verse optimizer replicates the phenomenon of the formation of new universes as described by multi-verse theory to solve complex real-world optimization problems. The proposed WLS–MVO framework is tested and validated by estimating the harmonics present in multiple test signals with different noise levels. Amplitudes and phases of harmonics present in the polluted signal were estimated, and the framework computational time was compared with the previously developed technique’s results which are reported in the literature. There was 80% reduction in computational time and 82% improvement in terms of accuracy in estimating harmonics using WLS–MVO as compared to previously developed techniques. The performance of the developed framework is further validated by estimating the harmonics present in the real-time voltage and current waveforms obtained from axial flux permanent magnet generator (AFPMSG), uninterruptible power supply (UPS), and light-emitting diode (LED). The purposed technique technique outperforms the already-developed techniques, in terms of accuracy and computational time
Alleviation of Heat Stress in Tomato by Exogenous Application of Sulfur
No full textTemperature is a key factor influencing plant growth and productivity, however sudden increases in temperature can cause severe consequences in terms of crop performance. We evaluated the influence of elementary sulfur application on the physiology and growth of two tomato genotypes (“Ahmar” and “Roma”) grown in two growth chambers (at 25 and 45 °C). Plants were sprayed with 2, 4, 6, and 8 ppm sulfur 45 days after sowing (untreated plants were kept as control). Plants of the “Roma” cultivar receiving 6 ppm sulfur exhibited maximal shoot and root biomass values followed by those receiving 4 ppm under both temperature conditions. Maximal CO2 index, photosynthetic rate, transpiration rate, and greenness index values (188.1 µmol mol−1, 36.3 µmol CO2 m−2 s−1, 1.8 µmol H2O m−2 s−1, and 95 SPAD, respectively) were observed in plants of “Roma” cultivar grown at 25 °C, indicating positive influences of sulfur on tomato physiology. Similarly, sulfur maximized proline, nitrogen, phosphorus, and potassium contents in leaves of both genotypes at both temperatures. The differences between control and sulfur-treated plants grown under heat stress indicate a possible role of sulfur in mitigating heat stress. Overall, our results suggest that 6 ppm of sulfur is the best dose to alleviate tomato heat stress and enhance the morphological, physiological, and biochemical attributes of tomato plants
Exogenous Application of Mg, Zn and B Influences Phyto-Nutritional Composition of Leaves and Fruits of Loquat (Eriobotrya japonica Lindl.)
No full textThis study was conducted to analyze the effect of magnesium (Mg), zinc (Zn) and boron (B) on the level of macronutrients (Na, Mg, K, Ca), micronutrients (Zn, B, Mo, Mn, Fe, Co, Ni, Cu), and heavy metals (Cd, As, Hg, Pb) in loquat leaves and fruit tissues (peel, pulp, and seed) using inductively coupled plasma-mass spectrometry (ICP-MS). Fruits were obtained from a loquat orchard located in Fujian (Yun Xiao/Zhangzhou). The results revealed that the foliar application of Mg increased the concentrations of Mg, K, Ca, Zn, B, Mn, Ni, and Cu in leaves; Mg, Ca, Zn, B, Mo, and Mn in fruit pulp; and Na, K, B, Mo, Co, Ni, and Cu in seeds. Zinc increased Mg, K, Ca, Zn, B, Ni, and Cu in leaves; Fe, Co and Ni in fruit peel; K, B, Mn, Fe, and Co in fruit pulp; and Na and K in seeds. Similarly, B application increased the concentrations of Na, Mg, K, Ca, and B in leaves; Ca and Ni in fruit peel; Na, Mg, Ca, Zn, B, Mn, Fe, and Co in fruit pulp; and Na, K, Ca, Zn, B, Mo, Mn, Co, and Ni in loquat seeds. Overall, mineral concentrations detected in the leaves and fruit tissues of loquats were greatly influenced by the application of Mg, Zn and B. Although heavy metal concentrations in fruit pulp were increased by the foliar application of B, the fruits were under safe limits for human consumption
Meta-analysis of randomized controlled trials only exploring the role of single incision laparoscopic surgery versus conventional multiport laparoscopic surgery for colorectal resections
No full textBurnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey
No full textBackground: 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
Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey
No full textBackground: 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
