scholarly journals A Preventive Strategy of Voltage Stability based on Characteristic Analysis

2019 ◽  
Vol 115 ◽  
pp. 01001
Author(s):  
Zhen Hu ◽  
Ding Wang ◽  
Yangwu Shen ◽  
Daojun Chen ◽  
Yongyan Liu

The purpose of voltage stability prevention and control strategy is to minimize the impact of expected accidents on the whole power grid while ensuring safe power supply. In this paper, it is expected that the accident has a large impact on the system voltage and makes the voltage margin of each node low. in order to not only adjust the node voltage, but also reduce the disturbance impact, a voltage stability prevention and control strategy is proposed based on the characteristic analysis.

2020 ◽  
Vol 77 (11) ◽  
pp. 1154-1160
Author(s):  
Danijela Ilic ◽  
Goran Videnovic ◽  
Ruzica Kozomara ◽  
Sonja Radakovic ◽  
Zoran Vlahovic ◽  
...  

Background/Aim. Non-melanoma skin cancers (NMSC) are ones of the most rapidly increasing cancers worldwide. Although NMSCs have a relatively low mortality rate, they are an important public health concern and the most costly cancers in many countries. The two main objectives in this study were: first, to analyze the trend of age-standardized incidence rate of NMSCs in Serbia and second, to assess the need for national prevention and control strategy based on analyzed trend. Methods. From the Serbian Cancer Registry, we extracted all cases of NMSCs registered in central Serbia from January 1, 1999 to December 31, 2015. Joinpoint regression analysis was used to define trends and annual percentage change (APC). Results. NMSCs significantly increased for both genders with APC of +2.32% (p < 0.001). Significantly increasing trend of incidence rates was higher in women (APC, +2.63%; p < 0.0001) than in men (APC, +2.01%; p < 0.001). Conclusion. Our results show a continuously increasing incidence rate of NMCS in Serbia. Without the national preventive strategy, current sporadic activities are highly unlikely to result in reducing the growing trends


Author(s):  
Gavin H. West ◽  
Laura S. Welch

This chapter describes the hazards for construction workers, with a particular focus on injuries as well as exposures to hazardous chemicals and dusts. A section describes hazardous exposures to lead and other heavy metals. Another section describes noise exposure. The impact of musculoskeletal disorders among construction workers is then discussed. A section on respiratory diseases focuses on asbestosis, silicosis, chronic obstructive pulmonary disease, and asthma. Exposures known to cause dermatitis and cancer are reviewed. There is a discussion of engineered nanomaterials as a potential emerging hazard. Various approaches to prevention and control, including regulations and health services, are described.


2021 ◽  
Vol 10 (7) ◽  
pp. 479
Author(s):  
Yihang Li ◽  
Liyan Xu

The COVID-19 pandemic is a major challenge for society as a whole, and analyzing the impact of the spread of the epidemic and government control measures on the travel patterns of urban residents can provide powerful help for city managers to designate top-level epidemic prevention policies and specific epidemic prevention measures. This study investigates whether it is more appropriate to use groups of POIs with similar pedestrian flow patterns as the unit of study rather than functional categories of POIs. In this study, we analyzed the hour-by-hour pedestrian flow data of key locations in Beijing before, during, and after the strict epidemic prevention and control period, and we found that the pedestrian flow patterns differed greatly in different periods by using a composite clustering index; we interpreted the clustering results from two perspectives: groups of pedestrian flow patterns and functional categories. The results show that depending on the specific stage of epidemic prevention and control, the number of unique pedestrian flow patterns decreased from four before the epidemic to two during the strict control stage and then increased to six during the initial resumption of work. The restrictions on movement are correlated with most of the visitations, and the release of restrictions led to an increase in the variety of unique pedestrian flow patterns compared to that in the pre-restriction period, even though the overall number of visitations decreased, indicating that social restrictions led to differences in the flow patterns of POIs and increased social distance.


2020 ◽  
Author(s):  
Denise van Hout ◽  
Paul Hutchinson ◽  
Marta Wanat ◽  
Caitlin Pilbeam ◽  
Herman Goossens ◽  
...  

ABSTRACTBackgroundWorking under pandemic conditions exposes health care workers (HCWs) to infection risk and psychological strain. Protecting the physical and psychological health of HCWs is a key priority. This study assessed the perceptions of European hospital HCWs of local infection prevention and control (IPC) procedures during the COVID-19 pandemic and the impact on their emotional wellbeing.MethodsWe performed two rounds of an international cross-sectional survey, between 31 March and 17 April 2020 via existing research networks (round 1), and between 14 May and 31 August 2020 via online convenience sampling (round 2). Main outcome measures were (1) behavioural determinants of HCW adherence with IPC procedures, (2) WHO-5 Well-Being Index, a validated scale of 0-100 reflecting emotional wellbeing. The WHO-5 was interpreted as a score below or above 50 points, a cut-off score used in previous literature to screen for depression.Results2,289 HCWs (round 1: n=190, round 2: n=2,099) from 40 countries in Europe participated. Mean age of respondents was 42 (±11) years, 66% were female, 47% and 39% were medical doctors and nurses, respectively. 74% (n=1699) of HCWs were directly treating patients with COVID-19, of which 32% (n=527) reported they were fearful of caring for these patients. HCWs reported high levels of concern about COVID-19 infection risk to themselves (71%) and their family (82%) as a result of their job. 40% of HCWs considered that getting infected with COVID-19 was not within their control. This was more common among junior than senior HCWs (46% versus 38%, P value <.01). Sufficient COVID-19-specific IPC training, confidence in PPE use and institutional trust were positively associated with the feeling that becoming infected with COVID-19 was within their control. Female HCWs were more likely than males to report a WHO-5 score below 50 points (aOR 1.5 (95% confidence interval (CI) 1.2-1.8).ConclusionsIn Europe, the COVID-19 pandemic has had a differential impact on those providing direct COVID-19 patient care, junior staff and women. Health facilities must be aware of these differential impacts, build trust and provide tailored support for this vital workforce during the current COVID-19 pandemic.


2020 ◽  
Vol 8 ◽  
Author(s):  
Zhong Sun ◽  
Guozhong He ◽  
Ninghao Huang ◽  
Hongyu Chen ◽  
Shuwei Zhang ◽  
...  

Background: COVID-19 developed into a global pandemic in 2020 and poses challenges regarding the prevention and control capabilities of countries. A large number of inbound travelers from other regions could lead to a renewed outbreak of COVID-19 in the local regions. Globally, as a result of the imbalance in the control of the epidemic, all countries are facing the risk of a renewed COVID-19 outbreak brought about by travelers from epidemic areas. Therefore, studies on a proper management of the inbound travelers are urgent.Methods: We collected a total of 4,733,414 inbound travelers and 174 COVID-19 diagnosed patients in Yunnan province from 21 January 2020 to 20 February 2020. Data on place of origin, travel history, age, and gender, as well as whether they had suspected clinical manifestations for inbound travelers in Yunnan were collected. The impact of inbound travelers on the local epidemic was analyzed with a collinear statistical analysis and the effect of the control measures on the epidemic was evaluated with a sophisticated modeling approach.Results: Of the 174 COVID-19 patients, 60.9% were not from Yunnan, and 76.4% had a history of travel in Hubei. The amount of new daily cases in Yunnan was significant correlated with the number of inbound travelers from Hubei and suspected cases among them. Using Susceptible–Exposed–Infectious–Recovered (SEIR) model analysis, we found that the prevention and control measures dropped the local R0 down to 1.07 in Yunnan province.Conclusions: Our preliminary analysis showed that the proper management of inbound travelers from outbreak areas has a significantly positive effect on the prevention and control of the virus. In the process of resettlement, some effective measures taken by Yunnan province may provide an important reference for preventing the renewed COVID-19 outbreak in other regions.


2020 ◽  
Vol 5 ◽  
pp. 755-765
Author(s):  
Ofosuhene O. Apenteng ◽  
Prince P. Osei ◽  
Bismark Oduro ◽  
Mavis Pearl Kwabla ◽  
Noor Azina Ismail

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Yanyan Zuo ◽  
Rui Sun ◽  
Jiuyu Zang ◽  
Mingyin Zheng

Taking a hybrid electric vehicle using double-row planetary gear power coupling mechanism as a research object, this study proposes a coordinated control algorithm of “torque distribution, engine torque monitoring, and motor torque compensation” in an attempt to realize coordinated control for driving mode switching. Characteristic analysis of the power coupling mechanism was carried out, and the control strategy model in MATLAB/Simulink was built. Subsequently, the analysis of mode switching from the electric mode into joint driving mode was simulated. In addition, a multibody dynamics model of the power coupling mechanism was established and the simulation analysis during mode switching process was carried out. The results show that the proposed coordinated control strategy serves to effectively reduce the torque fluctuation and the impact degree during the mode switching process and improve the ride comfort of the vehicle. In the meantime, the time-domain and frequency-domain characteristics of gear meshing force and bearing restraint force indicate that the mode switching process of the dynamic coupling mechanism is quite stable and this control strategy contributes to improving the characteristics such as vibration and noise.


Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 39
Author(s):  
Jianfei Zhao ◽  
Minqi Hua ◽  
Tingzhang Liu ◽  
Tao Yu

Aiming at the function and technical requirements of high-power photovoltaic cell simulation, high-performance programmable logic power supply and dc motor simulation, a high frequency isolation hybrid topology and control strategy based on current-source/voltage-source converter was studied and proposed. Firstly, according to the performance requirements of photovoltaic cell analog power supply, the control strategy requirements of the high-precision wide-range hybrid topology were proposed. Secondly, the working principle of the new hybrid topology was analyzed. At the same time, the equivalent model of the new hybrid topology was simplified and established, and the overall control strategy of the hybrid topology based on current compensation and sliding mode variable structure was proposed. Finally, simulation and experimental research on the hybrid topology was carried out, and the experimental test of photovoltaic cell simulation was completed. The simulation and experimental results show that the hybrid topology and control strategy proposed in this paper has the characteristics of wide-range output regulation, fast dynamic response, high efficiency and high power factor, and can be used for high performance photovoltaic cell simulation, programmable logic power supply and DC motor simulation.


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