With regard to the lower density and energy of electrons in pulsed discharge plasma （PDP） at atmosphere, leading to the lower energy utilization of plasma, we propose a MgO cathode to enhance the plasma intensity ac...With regard to the lower density and energy of electrons in pulsed discharge plasma （PDP） at atmosphere, leading to the lower energy utilization of plasma, we propose a MgO cathode to enhance the plasma intensity according to field emission principle. The MgO cathode is prepared by an electro-depositing MgO film on a stainless steel plate. This way, the positive charges come to the cathode and accumulate on the surface of the MgO film, leading to the enhancement of the electric field intensity between the cathode and MgO film, and result in the strong emission of secondary electrons from the MgO cathode. As a result, the intensity of plasma can be enhanced. Herein, the effect of the MgO cathode on the intensity of PDP is investigated. It was shown that the discharge peak current was improved by 20% compared with that of without the MgO cathode. With increasing the MgO film thickness, discharge intensity, including the peak current, transforming charge and spectrum intensity first increased and then decreased. Higher enhancement of peak current, transforming charge and spectrum intensity were acquired with a higher peak voltage. Compared to a cathode without MgO film, the ozone production is higher with MgO cathode employed. The research proposes a novel approach for improving the intensity of discharge plasma, and also provides a reference for further application of PDP.展开更多
目的分析肺癌患者术后并发肺部感染(postoperative pulmonary infection in patients with lung cancer,PPILC)的危险因素。方法回顾性分析中山大学肿瘤防治中心2018年1-12月收治的472例行肺癌手术患者的资料,包括临床基本资料和实验室...目的分析肺癌患者术后并发肺部感染(postoperative pulmonary infection in patients with lung cancer,PPILC)的危险因素。方法回顾性分析中山大学肿瘤防治中心2018年1-12月收治的472例行肺癌手术患者的资料,包括临床基本资料和实验室检查结果等,应用单因素分析和logistic回归分析患者术后并发肺部感染的风险因素。结果10.6%的肺癌患者术后并发肺部感染;多因素分析结果显示:术前存在肺通气功能障碍、手术时间长、术后3天内需予辅助吸痰、行二次手术、氧分压低是患者术后并发肺部感染的独立危险因素(P<0.05)。结论医护人员应重点关注合并以上危险因素患者术后肺部感染的防治,尽早干预改善患者肺功能、咳痰能力等,以期改善患者预后。展开更多
As a typical clean and renewable energy, wind power is becoming more and more widely used in electrical industry. However, its characteristics of random and intermittent have brought serious problems to the power syst...As a typical clean and renewable energy, wind power is becoming more and more widely used in electrical industry. However, its characteristics of random and intermittent have brought serious problems to the power system, such as voltage fluctuation and insufficient reactive power. Based on the K-means clustering algorithm, this paper classifies the doubly-fed induction generators （DFIG） according to the operation of propeller pitch angle control. At the same time, to obtain the optimal parameter, advanced particle swarm optimization （PSO） is used. Then the dynamic model of DFIG under the network fault condition is built. What is more, the role that crowbar circuit plays in low voltage ride through （LVRT） is discussed. Finally, simulations in DigSILENT verify the model.展开更多
基金National Natural Science Foundation Committee of China (No. 51477025) for the financial support of this work
文摘With regard to the lower density and energy of electrons in pulsed discharge plasma （PDP） at atmosphere, leading to the lower energy utilization of plasma, we propose a MgO cathode to enhance the plasma intensity according to field emission principle. The MgO cathode is prepared by an electro-depositing MgO film on a stainless steel plate. This way, the positive charges come to the cathode and accumulate on the surface of the MgO film, leading to the enhancement of the electric field intensity between the cathode and MgO film, and result in the strong emission of secondary electrons from the MgO cathode. As a result, the intensity of plasma can be enhanced. Herein, the effect of the MgO cathode on the intensity of PDP is investigated. It was shown that the discharge peak current was improved by 20% compared with that of without the MgO cathode. With increasing the MgO film thickness, discharge intensity, including the peak current, transforming charge and spectrum intensity first increased and then decreased. Higher enhancement of peak current, transforming charge and spectrum intensity were acquired with a higher peak voltage. Compared to a cathode without MgO film, the ozone production is higher with MgO cathode employed. The research proposes a novel approach for improving the intensity of discharge plasma, and also provides a reference for further application of PDP.
文摘目的分析肺癌患者术后并发肺部感染(postoperative pulmonary infection in patients with lung cancer,PPILC)的危险因素。方法回顾性分析中山大学肿瘤防治中心2018年1-12月收治的472例行肺癌手术患者的资料,包括临床基本资料和实验室检查结果等,应用单因素分析和logistic回归分析患者术后并发肺部感染的风险因素。结果10.6%的肺癌患者术后并发肺部感染;多因素分析结果显示:术前存在肺通气功能障碍、手术时间长、术后3天内需予辅助吸痰、行二次手术、氧分压低是患者术后并发肺部感染的独立危险因素(P<0.05)。结论医护人员应重点关注合并以上危险因素患者术后肺部感染的防治,尽早干预改善患者肺功能、咳痰能力等,以期改善患者预后。
文摘As a typical clean and renewable energy, wind power is becoming more and more widely used in electrical industry. However, its characteristics of random and intermittent have brought serious problems to the power system, such as voltage fluctuation and insufficient reactive power. Based on the K-means clustering algorithm, this paper classifies the doubly-fed induction generators （DFIG） according to the operation of propeller pitch angle control. At the same time, to obtain the optimal parameter, advanced particle swarm optimization （PSO） is used. Then the dynamic model of DFIG under the network fault condition is built. What is more, the role that crowbar circuit plays in low voltage ride through （LVRT） is discussed. Finally, simulations in DigSILENT verify the model.
