34 research outputs found
A Hybrid Efficient PV-Battery Powered LED Lighting Scheme
As we all know now a day�s developing countries across Asia and Africa are hit with the serious energy crisis. So To fulfill the power demand people started looking towards renewable sources of energy such as solar and wind energy. In this paper fully controlled, flexible and self-adjusting LED lighting PV-Battery powered scheme using a pulse-width modulation (PWM) switching and controlled by a dual-loop error driven, time de-scaled, WM proportional-integral-derivative (WM-PID) control scheme for the PV-battery interfaced to the LED load. It decreases the amplitude of transient voltage and minimize inrush current for balancing common DC bus to the LED load. The new adjustable controller uses a directed dual-loop error-driven, error-time descaled controller for the PWM switching along with MOSFET/IGBT switches. The dual-action regulator uses error driven weighted modified (WM-PID) proportional-integral-derivative controller with quick response auxiliary derivative loops to achieve efficient control action
STUDYING THE PHENOMENON OF POVERTY IN THE COUNTRYSIDE OF THE DAHHAR DISTRICT IN YEMEN
This research aimed to study poverty in rural Yemen through the percentage, gap, and severity in addition to the standard economic analysis. The study showed that the poverty percent reached 97%, while the gap and severity reached 64, and 45% respectively. A study of the probability distribution of poverty indicators showed that the poverty percent ranged from a minimum of 95.4% to a high of 98.6% at a 95% confidence level. The poverty gap ranged from a low of 59.8% to a high of 68.2% at 95% confidence. The severity of poverty ranged from a minimum of 40.7% to a high of 49.3% at 95% confidence. These results of the study are emphasized on the need for the implementation of several policies. Among these two most important are (1) expanding the activity of NGOs to reduce poverty and hunger, (2) focusing on sustainable development and increasing the economic size of the agricultural sector and its relative importance to poverty reduction. To reduce poverty in the rural areas of the Republic of Yemen, the study recommends (1) the expansion of the activities of civil societies under government supervision to increase their ability to reduce poverty and hunger, (2) the provision of the necessary funding for the expansion of small investment projects that are commensurate with the capabilities and qualifications of poor families and (3) focusing on sustainable development of the agricultural sector is relative importance in reducing poverty
Measuring Impact of Air and Agricultural Soil Pollution on Social Development in Saudi Arabia
This research aimed to measure the impact of air and agricultural soil pollution on social development in Saudi Arabia from the period 1995–2019 by using social development indicators, concentrating on the percentages of expenditure on education and health, and the Human Development Index. In addition, this study uses multiple regressions in estimating the model to study the impact of air pollution and agricultural soil on social development. Results of the study showed that a 10% change in the number of chemical fertilizers and pesticides used in Saudi agriculture leads to a change in the total number of inpatients by 0.7% and 0.5%, respectively. It was also found that an increased percentage of health expenditure to total government spending by 10% leads to a decrease in the total number of patients in the hospital by 1.8%. An increase in air pollution, expressed as a 10% increase in CO2 emissions, increases the total number of hospitalized patients by 11.1%. The increasing total number of patients by 10% leads to a decrease in the total productivity of the worker, as an indicator of 1.8%. Furthermore, a change of 10% in the ratio of education expenditure to total government expenditure leads to a change in the same direction of the Human Development Index by 9.6%. In light of these results, it can be recommended that the country need to reduce air pollution by expanding the use of natural gas in the industrial and transportation sectors, in addition to reducing the use of nitrogenous fertilizers and pesticides in Saudi agriculture through the expansion of clean farming and good agricultural practices
Development model for supply chain network design by demand uncertainty and mode selection
It is necessary to consider the impact of demand uncertainty to model the comprehensive approach for supply chain network design. This paper presents four echelons, multiple commodity, and strategic–tactical model for designing supply chain network. Uncertain demand, transportation mode selection with lead time configuration has been considered. A numerical example has been implemented to verify the applicability of model. Finally, the simulation results and sensitivity analysis confirm that the proposed developed model is a suitable decision framework for designing the supply chain network
Evaluating the effectiveness of integrated benders decomposition algorithm and epsilon constraint method for multi-objective facility location problem under demand uncertainty
One of the most challenging issues in multi-objective problems is finding Pareto optimal points. This paper describes an algorithm based on Benders Decomposition Algorithm (BDA) which tries to find Pareto solutions. For this aim, a multi-objective facility location allocation model is proposed. In this case, an integrated BDA and epsilon constraint method are proposed and it is shown that how Pareto points in multi-objective facility location model can be found. Results are compared with the classic form of BDA and the weighted sum method for demand uncertainty and deterministic demands. To do this, Monte Carlo method with uniform function is used, then the stability of the proposed method towards demand uncertainty is shown. In order to evaluate the proposed algorithm, some performance metrics including the number of Pareto points, mean ideal points, and maximum spread are used, then the t-test analysis is done which points out that there is a significant difference between aforementioned algorithms
Biological activities of Pereskia bleo extracts
The aim of this study is to screen the hexane, dicholoromethane, ethyl acetate and methanol extracts of Pereskia bleo (PB) for their antibacterial, anti-oxidant and anti-cancer properties using disc diffusion method, DPPH assay and MTT cytotoxicity test, respectively. It is found that hexane and methanol extracts showed highly and moderately, respectively, considerable antibacterial activity towards two Gram-negative bacteria, P. aeruginosa 60690 and S. choleraesuis. Ethyl acetate extract showed a week narrow spectrum activity (= 35% of streptomycin activity). The highest antibacterial activity on MRSA is obtained by DCM extract. Hexane extract was the most effective DPPH radical scavenger (37.55%). Ethyl acetate and DCM extracts were less effective free radical scavenger (16.1%). None of the extracts were cytotoxic significantly towards MCF-7, HT-29 and CEM-SS cell lines after 72 h incubation time (IC50 > 30 μg mL-1). It could be concluded that antibacterial activity of P. bleo is the most promising biological activity attributed to this plant
Microbiologically-influenced corrosion of the electroless-deposited NiP-TiNi – Coating
In this study, we reveal the microbiologically influenced corrosion (MIC) behavior of the new electroless NiP-TiNi nanocomposite coating in simulated seawater using the electrochemical impedance spectroscopy (EIS) technique after different periods of incubation time (7, 10, 14, 21, 28 days) in a sulfate-reducing bacteria (SRB) medium. The biofilm formation and the corrosion products were characterized using the scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The EIS results revealed the carbon steel (CS)/NiP-TiNi and NiP-TiNi/SRB biofilm interfaces' characteristics after different incubation times in the SRB media. EIS measurements revealed that the NiP-TiNi nanocomposite coating's MIC resistances are superior relative to API X80 carbon steel and a TiNi-free NiP coating, with ∼93% of corrosion inhibition efficiency after 28 days of incubation
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
Dağıtım Sistemleri için Kendinden Ayarlanabilir FACTS Cihazı ve Denetleyicisi
In this paper, a FACTS based dynamic switched C-type filter (DSCTF) compensator scheme for
distribution systems is presented with different load characteristics and control strategies. In order to
suppress power quality problems and increase overall energy utilization efficiency; design and digital
realization of the DSCTF consisting of dynamic control strategies are studied. Matlab/Simulink
Software Environment is employed to validate the effectiveness of FACTS DSCTF device. It has been
shown that the proposed FACTS-DSCTF is effective to mitigate power quality and energy utilization
problems as well as in compensating voltage disturbances and current harmonics.Bu çalışmada, dağıtım sistemleri için FACTS tabanlı dinamik anahtarlamalı C-tipi filtre (DSCTF)
kompanzatörü, farklı denetim stratejileri ve yük karakteristikleri ile sunulmaktadır. Enerji kullanım
verimini artırmak ve güç kalitesi problemlerini bastırmak için dinamik denetim stratejilerini içeren
DSCTF nin tasarımı ve dijital gerçekleştirilmesi çalışılmıştır. FACTS DSCTF cihazının etkinliğini doğrulamak
için Matlab/Simulink yazılım ortamı kullanılmıştır. Önerilen FACTS-DSCTF in güç kalitesi ve enerji
kullanım problemlerini azaltmanın yanı sıra gerilim bozukluklarını ve akım harmoniklerini de
kompanzasyonunda etkili olduğunu göstermektedir
A GA-ANFIS Self Regulating Scheme for Induction Motor Filter Compensation
Abstract The paper presents a Novel Green Plug-Filter Co mpensation Scheme developed by the Second Author and controlled by an integrated Genetics algorith m (GA) with Adaptive Neuro-Fu zzy Inference System (ANFIS) controller developed by the First Author for gain adjusting of a PID tri-loop stage control scheme applied on single phase Induction motor. A Tri Loop dynamic error controlled technique is used to reduce inrush current conditions, improve energy utilizat ion, ensure soft starting, reduce inrush current as well as effectively ensure motor dynamic speed tacking.The proposed technique is used to adjust the feeding of PWM switching of GP-FC by finding the optimal control gain settings that dynamically minimize the global dynamic error. Digital simu lations are provided to validate the effectiveness of this device in improving the power quality and system stability