The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electroc...The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.展开更多
The positron lifetime spectra of severalAl_(93.3-x)Fe_(4.3)V_(0.7)Si_(1.7)Mm_x (x = 0.5%, 1.0%, 3.0%, atom fraction) alloys with differentcontent of misch metal prepared by rapid solidification were measured, and the ...The positron lifetime spectra of severalAl_(93.3-x)Fe_(4.3)V_(0.7)Si_(1.7)Mm_x (x = 0.5%, 1.0%, 3.0%, atom fraction) alloys with differentcontent of misch metal prepared by rapid solidification were measured, and the variations on theinterfacial defects with the content of misch metal were revealed by an analysis of the lifetimeresults. The interface characteristics derived from the lifetime results could be used to give asatisfactory interpretation of the dependence of mechanical properties on the content of mischmetal.展开更多
欧洲血管外科学会(ESVS)于2021年在《European Journal of Vascular and Endovascular Surgery》发表了该协会首个静脉血栓诊疗领域的指南:《欧洲血管外科学会(ESVS)2021年静脉血栓管理临床实践指南》,该指南包括了下肢深静脉血栓形成(D...欧洲血管外科学会(ESVS)于2021年在《European Journal of Vascular and Endovascular Surgery》发表了该协会首个静脉血栓诊疗领域的指南:《欧洲血管外科学会(ESVS)2021年静脉血栓管理临床实践指南》,该指南包括了下肢深静脉血栓形成(DVT)、上肢DVT、浅静脉血栓形成(SVT)以及特殊部位血栓形成等方面,共给予了72条推荐意见;同时,除了关于治疗方法的推荐,还包括了健康经济学以及特殊患者人群的相关问题。该指南中的建议是通过对目前可以得到的研究证据进行分析及评估制定的,会对临床实践有较大的借鉴意义,但是,随着技术、证据以及知识的发展,指南可能需要不断更新。笔者团队根据指南更新的循证医学证据,结合临床中的热点问题,对指南给出的推荐意见做重点解读,以期更好地理解指南原则及实用建议。展开更多
基金co-supported by the National Key R&D Program of China(No.2020YFC2201001)the Shenzhen Science and Technology Program(No.20210623091808026).
文摘The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.
基金This work is supported by the National Natural Science Foundation of China (No. 59771020)
文摘The positron lifetime spectra of severalAl_(93.3-x)Fe_(4.3)V_(0.7)Si_(1.7)Mm_x (x = 0.5%, 1.0%, 3.0%, atom fraction) alloys with differentcontent of misch metal prepared by rapid solidification were measured, and the variations on theinterfacial defects with the content of misch metal were revealed by an analysis of the lifetimeresults. The interface characteristics derived from the lifetime results could be used to give asatisfactory interpretation of the dependence of mechanical properties on the content of mischmetal.
文摘欧洲血管外科学会(ESVS)于2021年在《European Journal of Vascular and Endovascular Surgery》发表了该协会首个静脉血栓诊疗领域的指南:《欧洲血管外科学会(ESVS)2021年静脉血栓管理临床实践指南》,该指南包括了下肢深静脉血栓形成(DVT)、上肢DVT、浅静脉血栓形成(SVT)以及特殊部位血栓形成等方面,共给予了72条推荐意见;同时,除了关于治疗方法的推荐,还包括了健康经济学以及特殊患者人群的相关问题。该指南中的建议是通过对目前可以得到的研究证据进行分析及评估制定的,会对临床实践有较大的借鉴意义,但是,随着技术、证据以及知识的发展,指南可能需要不断更新。笔者团队根据指南更新的循证医学证据,结合临床中的热点问题,对指南给出的推荐意见做重点解读,以期更好地理解指南原则及实用建议。
