本文论述了一种简便易行的非自喷井DST流动期或段塞流压力历史分析新方法(?)FMRH法(Flow Period Maximum Rate Horner Method,流动期最大产量Horner分析方法)。方法基于Jones等人推出的常产量压降试井分析的理论结论,结合DST不同于常产...本文论述了一种简便易行的非自喷井DST流动期或段塞流压力历史分析新方法(?)FMRH法(Flow Period Maximum Rate Horner Method,流动期最大产量Horner分析方法)。方法基于Jones等人推出的常产量压降试井分析的理论结论,结合DST不同于常产量压降试井的生产特点,将DST流动期视为压力恢复的续流期,以流动期的初始产量为常产量进行分析。对实际资料的处理表明,新方法的应用不仅能提高分析效率,而且将提高分析结果的正确性。展开更多
A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical bound...A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.展开更多
Two results on the formation of singularities in solutions to the system of one-dimensional hydromagnetic dynamics are presented.In particular,it is shown that shocks form from a smooth spatial periodic flow in a fini...Two results on the formation of singularities in solutions to the system of one-dimensional hydromagnetic dynamics are presented.In particular,it is shown that shocks form from a smooth spatial periodic flow in a finite time if the initial amounts of entropy and the “magnetic field” in each period are smaller than those of sound waves.A quantitative estimate of blow-up time is also given.展开更多
Objective There are still a high proportion of patients with ST-segment elevation myocardial infarction （STEMI） missing out early reperfusion even in the primary percutaneous coronary intervention （PCI） era. Most ...Objective There are still a high proportion of patients with ST-segment elevation myocardial infarction （STEMI） missing out early reperfusion even in the primary percutaneous coronary intervention （PCI） era. Most of them are stable latecomers, but the optimal time to undergo delayed PCI for stable ones remains controversial. Methods We investigated all STEMI patients who underwent delayed PCI （2-28 days after STEMI） during 2007-2010 in Beijing and excluded patients with hemodynamic instability. The primary outcome was maj or adverse cardiovascular events （MACEs）. Results This study finally enrolled 5,417 STEMI patients and assigned them into three groups according to individual delayed time （Early group, 55.9%; Medium group, 35.4%; Late group, 8.7%）. During 1-year follow-up, MACEs occurred in 319 patients. The incidence of MACEs were respectively 7.1%, 5.6% and 6.7% among three groups. The Medium group had less recurrent myocardial infarction plus cardiac death （hazard ratio, 0.525; 95% confidence interval, 0.294-0.938, P = 0.030） than Late group and less repeat revascularization （hazard ratio, 0.640; 95% confidence interval, 0.463-0.883, P = 0.007） than Early group in pairwise comparisons. We depicted the incidence of major adverse cardiovascular event （MACE） by delayed time as a quadratic curve and found the bottom appeared at day 14. Conclusions The delayed PCI time varied in the real-world practice, but undergoing operations on the second week after STEMI had greater survival benefit and less adverse events for whom without early reperfusion and hemodynamic instability.展开更多
文摘本文论述了一种简便易行的非自喷井DST流动期或段塞流压力历史分析新方法(?)FMRH法(Flow Period Maximum Rate Horner Method,流动期最大产量Horner分析方法)。方法基于Jones等人推出的常产量压降试井分析的理论结论,结合DST不同于常产量压降试井的生产特点,将DST流动期视为压力恢复的续流期,以流动期的初始产量为常产量进行分析。对实际资料的处理表明,新方法的应用不仅能提高分析效率,而且将提高分析结果的正确性。
基金the financial support from the National Natural Science Foundation of China (Nos. 52005297, 52035005)the Key Research and Development Program of Shandong Province, China (No. 2021ZLGX01)。
文摘A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.
文摘Two results on the formation of singularities in solutions to the system of one-dimensional hydromagnetic dynamics are presented.In particular,it is shown that shocks form from a smooth spatial periodic flow in a finite time if the initial amounts of entropy and the “magnetic field” in each period are smaller than those of sound waves.A quantitative estimate of blow-up time is also given.
文摘Objective There are still a high proportion of patients with ST-segment elevation myocardial infarction （STEMI） missing out early reperfusion even in the primary percutaneous coronary intervention （PCI） era. Most of them are stable latecomers, but the optimal time to undergo delayed PCI for stable ones remains controversial. Methods We investigated all STEMI patients who underwent delayed PCI （2-28 days after STEMI） during 2007-2010 in Beijing and excluded patients with hemodynamic instability. The primary outcome was maj or adverse cardiovascular events （MACEs）. Results This study finally enrolled 5,417 STEMI patients and assigned them into three groups according to individual delayed time （Early group, 55.9%; Medium group, 35.4%; Late group, 8.7%）. During 1-year follow-up, MACEs occurred in 319 patients. The incidence of MACEs were respectively 7.1%, 5.6% and 6.7% among three groups. The Medium group had less recurrent myocardial infarction plus cardiac death （hazard ratio, 0.525; 95% confidence interval, 0.294-0.938, P = 0.030） than Late group and less repeat revascularization （hazard ratio, 0.640; 95% confidence interval, 0.463-0.883, P = 0.007） than Early group in pairwise comparisons. We depicted the incidence of major adverse cardiovascular event （MACE） by delayed time as a quadratic curve and found the bottom appeared at day 14. Conclusions The delayed PCI time varied in the real-world practice, but undergoing operations on the second week after STEMI had greater survival benefit and less adverse events for whom without early reperfusion and hemodynamic instability.
