Aiming at machining deeply small holes in TC4 alloy,a series of experiments were carried out on a self-developed multi-axis micro electrical discharge machining(micro-EDM)machine tool.To improve machining efficiency a...Aiming at machining deeply small holes in TC4 alloy,a series of experiments were carried out on a self-developed multi-axis micro electrical discharge machining(micro-EDM)machine tool.To improve machining efficiency and decrease relative wear of electrode in machining deeply small hole in TC4 alloy,many factors in micro-EDM,such as polarity,electrical parameters and supplying ways of working fluid were studied.Experimental results show that positive polarity machining is far superior to negative polarity machining;it is more optimal when open-circuit voltage,pulse width and pulse interval are 130 V,5μs and 15μs respectively on the self developed multi-axis micro-EDM machine tool;when flushing method is applied in micro-EDM,the machining efficiency is higher and relative wear of electrode is smaller.展开更多
Electrochemical drilling(ECD)provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines.The value and fluctuation ...Electrochemical drilling(ECD)provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines.The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD.In particular,when drilling multiple holes,the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among multiple tube electrodes,thereby affecting the machining stability and the maximum feed rate.Thus,an eight-channel flow control system was developed to measure and regulate in real time the electrolyte flowrate supplied into each individual tube electrode.This paper proposes ECD of small holes with real-time flowrate control to improve the uniformity of electrolyte flowrate in each tube electrode and reduce the fluctuations in the electrolyte flowrate.In single-hole drilling,when the electrolyte flowrate was regulated in real time,the hole quality and machining stability were considerably better than without regulation.This is because the electrolyte flowrate remains basically constant,which stabilizes the flow field.Moreover,by considering the hole profile,it was found that an electrolyte flowrate of 200.0 m L/min can be acceptable for ECD of small holes.When the eight-channel flow control system was used in multiple-hole drilling,the uniformity of the electrolyte flowrate in each tube electrode was obviously improved,which led to a more stable process.Additionally,the maximum feed rate can attain 2.40 mm/min in multiple-hole drilling.Based on these findings,a matrix(5×32)of multiple small holes was successfully fabricated with a satisfactory diameter consistency,as the machining stability and machining efficiency had been enhanced.展开更多
For plane singly-connected domains with insulating boundary and four point-sized contacts, C<sub>0</sub> …C<sub>3</sub>, van der Pauw derived a famous equation relating the two trans-...For plane singly-connected domains with insulating boundary and four point-sized contacts, C<sub>0</sub> …C<sub>3</sub>, van der Pauw derived a famous equation relating the two trans-resistances R<sub>01,23</sub>, R<sub>12,30</sub> with the sheet resistance without any other parameters. If the domain has one hole van der Pauw’s equation becomes an inequality with upper and lower bounds, the envelopes. This was conjectured by Szymański et al. in 2013, and only recently it was proven by Miyoshi et al. with elaborate mathematical tools. The present article gives new proofs closer to physical intuition and partly with simpler mathematics. It relies heavily on conformal transformation and it expresses for the first time the trans-resistances and the lower envelope in terms of Jacobi functions, elliptic integrals, and the modular lambda elliptic function. New simple formulae for the asymptotic limit of a very large hole are also given.展开更多
目的探讨不同切口手术联合加速康复外科(enhanced recovery after surgery,ERAS)理念指导下的呼吸功能训练在肺癌患者中的应用效果。方法选择2020年1月至2022年12月在苏州大学附属太仓医院择期行肺癌根治术的患者200例,随机分为4组,每...目的探讨不同切口手术联合加速康复外科(enhanced recovery after surgery,ERAS)理念指导下的呼吸功能训练在肺癌患者中的应用效果。方法选择2020年1月至2022年12月在苏州大学附属太仓医院择期行肺癌根治术的患者200例,随机分为4组,每组50例。A组接受单孔胸腔镜手术,术前ERAS宣教,呼吸训练器和常规呼吸功能训练;B组接受腋下肌肉非损伤性小切口手术,术前ERAS宣教,呼吸训练器和常规呼吸功能训练;C组接受腋下肌肉非损伤性小切口手术,术前常规宣教和常规呼吸功能训练;D组接受单孔胸腔镜手术,术前常规宣教和常规呼吸功能训练。比较4组患者术后恢复情况及术后疼痛评分。结果与其他3组相比,A组患者肺部并发症发生率降低,下床时间更早,置管时间、住院时间均缩短(P<0.05);与B组、C组相比,A组患者术后疼痛显著减轻(P<0.05)。与C组相比,B组患者肺部并发症发生率降低,下床时间、置管时间、住院时间缩短(P<0.05)。手术切口相同组间的术后疼痛差异无统计学意义。结论单孔胸腔镜肺癌手术联合ERAS理念指导下的呼吸功能训练可明显降低患者术后肺部并发症发生率,减轻术后疼痛,加速康复。展开更多
基金Project(2006AA04Z323)supported by High-tech Research and Development Program of China。
文摘Aiming at machining deeply small holes in TC4 alloy,a series of experiments were carried out on a self-developed multi-axis micro electrical discharge machining(micro-EDM)machine tool.To improve machining efficiency and decrease relative wear of electrode in machining deeply small hole in TC4 alloy,many factors in micro-EDM,such as polarity,electrical parameters and supplying ways of working fluid were studied.Experimental results show that positive polarity machining is far superior to negative polarity machining;it is more optimal when open-circuit voltage,pulse width and pulse interval are 130 V,5μs and 15μs respectively on the self developed multi-axis micro-EDM machine tool;when flushing method is applied in micro-EDM,the machining efficiency is higher and relative wear of electrode is smaller.
基金supported by the Joint Funds of the National Natural Science Foundation of China and Guangdong Province(No.U1601201)the National Natural Science Foundation of China for Creative Research Groups(No.51921003)。
文摘Electrochemical drilling(ECD)provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines.The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD.In particular,when drilling multiple holes,the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among multiple tube electrodes,thereby affecting the machining stability and the maximum feed rate.Thus,an eight-channel flow control system was developed to measure and regulate in real time the electrolyte flowrate supplied into each individual tube electrode.This paper proposes ECD of small holes with real-time flowrate control to improve the uniformity of electrolyte flowrate in each tube electrode and reduce the fluctuations in the electrolyte flowrate.In single-hole drilling,when the electrolyte flowrate was regulated in real time,the hole quality and machining stability were considerably better than without regulation.This is because the electrolyte flowrate remains basically constant,which stabilizes the flow field.Moreover,by considering the hole profile,it was found that an electrolyte flowrate of 200.0 m L/min can be acceptable for ECD of small holes.When the eight-channel flow control system was used in multiple-hole drilling,the uniformity of the electrolyte flowrate in each tube electrode was obviously improved,which led to a more stable process.Additionally,the maximum feed rate can attain 2.40 mm/min in multiple-hole drilling.Based on these findings,a matrix(5×32)of multiple small holes was successfully fabricated with a satisfactory diameter consistency,as the machining stability and machining efficiency had been enhanced.
文摘For plane singly-connected domains with insulating boundary and four point-sized contacts, C<sub>0</sub> …C<sub>3</sub>, van der Pauw derived a famous equation relating the two trans-resistances R<sub>01,23</sub>, R<sub>12,30</sub> with the sheet resistance without any other parameters. If the domain has one hole van der Pauw’s equation becomes an inequality with upper and lower bounds, the envelopes. This was conjectured by Szymański et al. in 2013, and only recently it was proven by Miyoshi et al. with elaborate mathematical tools. The present article gives new proofs closer to physical intuition and partly with simpler mathematics. It relies heavily on conformal transformation and it expresses for the first time the trans-resistances and the lower envelope in terms of Jacobi functions, elliptic integrals, and the modular lambda elliptic function. New simple formulae for the asymptotic limit of a very large hole are also given.
文摘目的探讨不同切口手术联合加速康复外科(enhanced recovery after surgery,ERAS)理念指导下的呼吸功能训练在肺癌患者中的应用效果。方法选择2020年1月至2022年12月在苏州大学附属太仓医院择期行肺癌根治术的患者200例,随机分为4组,每组50例。A组接受单孔胸腔镜手术,术前ERAS宣教,呼吸训练器和常规呼吸功能训练;B组接受腋下肌肉非损伤性小切口手术,术前ERAS宣教,呼吸训练器和常规呼吸功能训练;C组接受腋下肌肉非损伤性小切口手术,术前常规宣教和常规呼吸功能训练;D组接受单孔胸腔镜手术,术前常规宣教和常规呼吸功能训练。比较4组患者术后恢复情况及术后疼痛评分。结果与其他3组相比,A组患者肺部并发症发生率降低,下床时间更早,置管时间、住院时间均缩短(P<0.05);与B组、C组相比,A组患者术后疼痛显著减轻(P<0.05)。与C组相比,B组患者肺部并发症发生率降低,下床时间、置管时间、住院时间缩短(P<0.05)。手术切口相同组间的术后疼痛差异无统计学意义。结论单孔胸腔镜肺癌手术联合ERAS理念指导下的呼吸功能训练可明显降低患者术后肺部并发症发生率,减轻术后疼痛,加速康复。
