Professors Mohazzbi and Luo [1] published “Despite several attempts have been made to explain the twin paradox … none of the explanations … resolved the paradox. If the paradox can be ever resolved, it requires a m...Professors Mohazzbi and Luo [1] published “Despite several attempts have been made to explain the twin paradox … none of the explanations … resolved the paradox. If the paradox can be ever resolved, it requires a much deeper understanding … of the theory of relativity”. The deeper understanding of resolving the paradox is by applying more explicit definitions of proper time interval, Lorentz transform, time dilation, and aging time.展开更多
Time-resolved particle image velocimetry（TRPIV） experiments are performed to investigate the coherent structure＇s performance of riblets in a turbulent boundary layer（TBL） at a friction Reynolds number of 185. To...Time-resolved particle image velocimetry（TRPIV） experiments are performed to investigate the coherent structure＇s performance of riblets in a turbulent boundary layer（TBL） at a friction Reynolds number of 185. To visualize the energetic large-scale coherent structures（CSs） over a smooth surface and riblets, the proper orthogonal decomposition（POD） and finite-time Lyapunov exponent（FTLE） are used to identify the CSs in the TBL. Spatial-temporal correlation is implemented to obtain the characters and transport properties of typical CSs in the FTLE fields. The results demonstrate that the generic flow structures, such as hairpin-like vortices, are also observed in the boundary layer flow over the riblets, consistent with its smooth counterpart. Low-order POD modes are more sensitive to the riblets in comparison with the high-order ones,and the wall-normal movement of the most energy-containing structures are suppressed over riblets. The spatial correlation analysis of the FTLE fields indicates that the evolution process of the hairpin vortex over riblets are inhibited. An apparent decrease of the convection velocity over riblets is noted, which is believed to reduce the ejection/sweep motions associated with high shear stress from the viscous sublayer. These reductions exhibit inhibition of momentum transfer among the structures near the wall in the TBL flows.展开更多
Making use of the maximum entropy method, we study the most probable source function in heavy ion collisions. An anisotropic Gaussian source is deduced by simply assuming that the particles are emitted within a finite...Making use of the maximum entropy method, we study the most probable source function in heavy ion collisions. An anisotropic Gaussian source is deduced by simply assuming that the particles are emitted within a finite proper-time. The general relations between the most probable source function and the minimal assumptions are discussed, which are instructive in constructing a self-consistent source function from observed Hanbury-Brown/Twiss（HBT） correlations.展开更多
目的对腹部手术全麻苏醒期躁动的相关因素进行分析,筛选出独立危险因素。方法观察腹部手术术后患者意识恢复情况,记录患者性别、年龄、体重、疾病类别、术前睡眠时间、麻醉时间、吸入麻醉用量、吸入麻醉停用时间、术中输液量、输血量、...目的对腹部手术全麻苏醒期躁动的相关因素进行分析,筛选出独立危险因素。方法观察腹部手术术后患者意识恢复情况,记录患者性别、年龄、体重、疾病类别、术前睡眠时间、麻醉时间、吸入麻醉用量、吸入麻醉停用时间、术中输液量、输血量、失血量、尿量。用Logistic回归分析研究影响全麻苏醒期躁动的相关因素。结果共有142例患者纳入分析,全麻苏醒期躁动发生率17.61%。年龄(B=-0.059,P=0.007,OR=0.943,95%CI of OR:0.902～0.986)和术前睡眠时间(B=-0.786,P=0.000,OR=0.455,95%CI of OR:0.317～0.655)对全麻苏醒期躁动具有显著影响。结论年龄和术前睡眠时间是影响腹部手术患者全麻苏醒期躁动的独立危险因素。展开更多
文摘Professors Mohazzbi and Luo [1] published “Despite several attempts have been made to explain the twin paradox … none of the explanations … resolved the paradox. If the paradox can be ever resolved, it requires a much deeper understanding … of the theory of relativity”. The deeper understanding of resolving the paradox is by applying more explicit definitions of proper time interval, Lorentz transform, time dilation, and aging time.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11332006,11732010,11572221,and 11502066)the Natural Science Foundation of Tianjin City(Grant No.18JCQNJC5100)
文摘Time-resolved particle image velocimetry（TRPIV） experiments are performed to investigate the coherent structure＇s performance of riblets in a turbulent boundary layer（TBL） at a friction Reynolds number of 185. To visualize the energetic large-scale coherent structures（CSs） over a smooth surface and riblets, the proper orthogonal decomposition（POD） and finite-time Lyapunov exponent（FTLE） are used to identify the CSs in the TBL. Spatial-temporal correlation is implemented to obtain the characters and transport properties of typical CSs in the FTLE fields. The results demonstrate that the generic flow structures, such as hairpin-like vortices, are also observed in the boundary layer flow over the riblets, consistent with its smooth counterpart. Low-order POD modes are more sensitive to the riblets in comparison with the high-order ones,and the wall-normal movement of the most energy-containing structures are suppressed over riblets. The spatial correlation analysis of the FTLE fields indicates that the evolution process of the hairpin vortex over riblets are inhibited. An apparent decrease of the convection velocity over riblets is noted, which is believed to reduce the ejection/sweep motions associated with high shear stress from the viscous sublayer. These reductions exhibit inhibition of momentum transfer among the structures near the wall in the TBL flows.
基金Supported by National Natural Science Foundation of China (10835005, 90503001, 90103019)
文摘Making use of the maximum entropy method, we study the most probable source function in heavy ion collisions. An anisotropic Gaussian source is deduced by simply assuming that the particles are emitted within a finite proper-time. The general relations between the most probable source function and the minimal assumptions are discussed, which are instructive in constructing a self-consistent source function from observed Hanbury-Brown/Twiss（HBT） correlations.
文摘目的对腹部手术全麻苏醒期躁动的相关因素进行分析,筛选出独立危险因素。方法观察腹部手术术后患者意识恢复情况,记录患者性别、年龄、体重、疾病类别、术前睡眠时间、麻醉时间、吸入麻醉用量、吸入麻醉停用时间、术中输液量、输血量、失血量、尿量。用Logistic回归分析研究影响全麻苏醒期躁动的相关因素。结果共有142例患者纳入分析,全麻苏醒期躁动发生率17.61%。年龄(B=-0.059,P=0.007,OR=0.943,95%CI of OR:0.902～0.986)和术前睡眠时间(B=-0.786,P=0.000,OR=0.455,95%CI of OR:0.317～0.655)对全麻苏醒期躁动具有显著影响。结论年龄和术前睡眠时间是影响腹部手术患者全麻苏醒期躁动的独立危险因素。
