Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by ...Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor,usually no interaction between them is consid-ered in pure liquid model.In this study,the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami.For model-ing the earthquake,firstly the initial stress field to generate the earthquake is set up,and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault.It is dif-ferent from seismic dislocation theory in which the relative slip on the fault is specified in advance.The modeling results reveal that P,SP and the surface wave can be found at the sea surface besides the tsunami wave.The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes,and its maximum amplitude is 0.55 m,which is 2 times as large as that of the sea floor.Tsunami warning information can be taken from the surface wave on the sea surface,which is much earlier than that obtained from the seismograph stations on land.The tsunami speed on the open sea with 3 km depth is 175.8 m/s,which is a little greater than that pre-dicted by long wave theory,(gh)1/2=171.5 m,and its wavelength and amplitude in average are 32 km and 2 m,respectively.After the tsunami propagates to the continental shelf,its speed and wavelength is reduced,but its amplitude become greater,especially,it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore,respectively.The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/s2 and 16.5 m/s2,respectively,the later is 2.8 times the former,and therefore,sea water is a good shock absorber.The acceleration at the sea shore is about 1/10 as large as at the epicenter.The maximum vertical velocity at the epicenter is 1.4 times that on the fault.The maximum vertical displacement at the fault is less than that at the epicenter.The difference between them is the amplitude of the tsunami at the epicenter.The time of the maximum displacement to occur on the fault is not at the beginning of the fault slipping but retards 23 s.展开更多
<div style="text-align:justify;"> This study demonstrates mathematical analysis of biodegradation processes of xenobiotic polymers. A model for microbial population is based on the fact that growth rat...<div style="text-align:justify;"> This study demonstrates mathematical analysis of biodegradation processes of xenobiotic polymers. A model for microbial population is based on the fact that growth rate of microorganisms is proportional to the microbial population and consumption rate of parts of carbon sources. The model is paired with a model for weight distribution. Those models lead to inverse problems for a molecular factor and a time factor of degradation rate. Solution of the inverse problems allows us to simulate the biodegra-dation process. </div>展开更多
目的研究比较以问题为基础的学习模式(Problem Based Learrning,PBL)与以授课为基础的传统学习模式(Lecture Based Learning,LBL)在急诊重症监护临床示教中的应用效果。方法选取2020年7月—2021年6月南华大学附属长沙中心医院100名医护...目的研究比较以问题为基础的学习模式(Problem Based Learrning,PBL)与以授课为基础的传统学习模式(Lecture Based Learning,LBL)在急诊重症监护临床示教中的应用效果。方法选取2020年7月—2021年6月南华大学附属长沙中心医院100名医护人员作为研究对象,将其分为PBL组和LBL组,探讨PBL学习模式和LBL学习模式在急诊重症监护临床示教中的应用效果情况。结果PBL组笔试考试和客观结构化临床考试得分为(95.28±2.19)分、(94.45±3.08)分,LBL组得分为(89.15±2.38)分、(82.79±2.23)分,差异有统计学意义(t=9.494、15.337,P均<0.05)。与LBL组相比,PBL组自主学习能力、积极性、理论联系实际、团队动力和注意力等自我评价方面均明显更优,寻求真相能力、分析能力、求知欲能力、系统化能力和认知成熟度等思维能力均明显更优,差异有统计学意义(P均<0.05)。结论PBL学习模式能够有效提升急诊重症监护临床示教中的应用效果。展开更多
基金National Natural Science Foundation of China (40521002 and 40474013).
文摘Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor,usually no interaction between them is consid-ered in pure liquid model.In this study,the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami.For model-ing the earthquake,firstly the initial stress field to generate the earthquake is set up,and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault.It is dif-ferent from seismic dislocation theory in which the relative slip on the fault is specified in advance.The modeling results reveal that P,SP and the surface wave can be found at the sea surface besides the tsunami wave.The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes,and its maximum amplitude is 0.55 m,which is 2 times as large as that of the sea floor.Tsunami warning information can be taken from the surface wave on the sea surface,which is much earlier than that obtained from the seismograph stations on land.The tsunami speed on the open sea with 3 km depth is 175.8 m/s,which is a little greater than that pre-dicted by long wave theory,(gh)1/2=171.5 m,and its wavelength and amplitude in average are 32 km and 2 m,respectively.After the tsunami propagates to the continental shelf,its speed and wavelength is reduced,but its amplitude become greater,especially,it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore,respectively.The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/s2 and 16.5 m/s2,respectively,the later is 2.8 times the former,and therefore,sea water is a good shock absorber.The acceleration at the sea shore is about 1/10 as large as at the epicenter.The maximum vertical velocity at the epicenter is 1.4 times that on the fault.The maximum vertical displacement at the fault is less than that at the epicenter.The difference between them is the amplitude of the tsunami at the epicenter.The time of the maximum displacement to occur on the fault is not at the beginning of the fault slipping but retards 23 s.
文摘<div style="text-align:justify;"> This study demonstrates mathematical analysis of biodegradation processes of xenobiotic polymers. A model for microbial population is based on the fact that growth rate of microorganisms is proportional to the microbial population and consumption rate of parts of carbon sources. The model is paired with a model for weight distribution. Those models lead to inverse problems for a molecular factor and a time factor of degradation rate. Solution of the inverse problems allows us to simulate the biodegra-dation process. </div>
文摘目的研究比较以问题为基础的学习模式(Problem Based Learrning,PBL)与以授课为基础的传统学习模式(Lecture Based Learning,LBL)在急诊重症监护临床示教中的应用效果。方法选取2020年7月—2021年6月南华大学附属长沙中心医院100名医护人员作为研究对象,将其分为PBL组和LBL组,探讨PBL学习模式和LBL学习模式在急诊重症监护临床示教中的应用效果情况。结果PBL组笔试考试和客观结构化临床考试得分为(95.28±2.19)分、(94.45±3.08)分,LBL组得分为(89.15±2.38)分、(82.79±2.23)分,差异有统计学意义(t=9.494、15.337,P均<0.05)。与LBL组相比,PBL组自主学习能力、积极性、理论联系实际、团队动力和注意力等自我评价方面均明显更优,寻求真相能力、分析能力、求知欲能力、系统化能力和认知成熟度等思维能力均明显更优,差异有统计学意义(P均<0.05)。结论PBL学习模式能够有效提升急诊重症监护临床示教中的应用效果。
