Dear Editor,This letter investigates global stabilization of uncertain nonlinear systems via adaptive event-triggered output feedback.Uncertainties lie in both system nonlinearities and measurement sensitivity.To this...Dear Editor,This letter investigates global stabilization of uncertain nonlinear systems via adaptive event-triggered output feedback.Uncertainties lie in both system nonlinearities and measurement sensitivity.To this end,a dynamic high gain is introduced to cope with the influence of large uncertainties,the unknown measurement sensitivity and the execution error,while a time-varying threshold event-triggering mechanism is constructed to effectively exclude the Zeno phenomenon.As such,the adaptive event-triggered control ensures globally bounded and convergent of system states.The design method is demonstrated using a controlled pendulum example.展开更多
The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the We...The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the Wenchuan Ms8.0 earthquake, we calculated the coulomb failure stress change. The inverted coulomb stress changes based on the Nishimura and Chenji models both show that the Lushan MT. 0 earth- quake occurred in the increased area of coulomb failure stress induced by the Wenchuan Ms8. 0 earthquake. The coulomb failure stress increased by approximately 0. 135 - 0. 152 bar in the source of the Lushan M7.0 earthquake, which is far more than the stress triggering threshold. Therefore, the Lushan M7.0 earthquake was most likely triggered by the coulomb failure stress change.展开更多
Recently published results of field and laboratory experiments on the seismic/acoustic response to injection of direct current （DC） pulses into the Earth crust or stressed rock samples raised a question on a possibi...Recently published results of field and laboratory experiments on the seismic/acoustic response to injection of direct current （DC） pulses into the Earth crust or stressed rock samples raised a question on a possibility of electrical earthquake triggering. A physical mechanism of the considered phenomenon is not clear yet in view of the very low current density （10-7-10-s A/m^2） generated by the pulsed power systems at the epicenter depth （5-10 km） of local earthquakes occurred just after the current injection. The paper describes results of laboratory ＂earthquake＂ triggering by DC pulses under conditions of a spring-block model simulated the seismogenic fault. It is experimentally shown that the electric triggering of the laboratory ＂earthquake＂ （sharp slip of a movable block of the spring-block system） is possible only within a range of subcritical state of the system, when the shear stress between the movable and fixed blocks obtains 0.98-0.99 of its critical value. The threshold of electric triggering action is about 20 A/m^2 that is 7-8 orders of magnitude higher than estimated electric current density for Bishkek test site （Northern Tien Shan, Kirghizia） where the seismic response to the man-made electric action was observed. In this connection, the electric triggering phenomena may be explained by contraction of electric current in the narrow conductive areas of the faults and the corresponding increase in current density or by involving the secondary triggering mechanisms like electromagnetic stimulation of conductive fluid migration into the fault area resulted in decrease in the fault strength properties.展开更多
BACKGROUND Borderline form of empty follicle syndrome is a condition in which only a few mature or immature oocytes are recovered after meticulous follicular aspiration,despite adequate ovarian response to stimulation...BACKGROUND Borderline form of empty follicle syndrome is a condition in which only a few mature or immature oocytes are recovered after meticulous follicular aspiration,despite adequate ovarian response to stimulation.It is a rare phenomenon with an unclear cause.Currently,the condition still lacks effective treatment.CASE SUMMARY A patient with secondary infertility who had undergone three cycles of assisted reproductive technique(ART)is described.With regard to good follicular response,two oocytes were obtained in the first two ART cycles,but no embryo was formed.In the third ART cycle,which is the subject of this study,ovulation was induced by dual trigger of a supernormal dose of human chorionic gonadotropin(HCG)combined with a delayed oocyte retrieval approach.The method involved administration of gonadotropin-releasing hormone agonist,recombinant HCG,and urinary HCG 39 h before ovum pick-up.Ten oocytes were recovered,two out of three mature eggs were fertilized after intracytoplasmic sperm injection,resulting in two embryos that were subsequently cryopreserved.The case report guidelines have been used herein to present the first case of this novel dual trigger method.CONCLUSION This approach provides a new treatment option for patients with a similar condition in the future.This study can also inspire further investigation on the effects of variousβ-HCG serum levels 36 h after intramuscular HCG administration.展开更多
Mass movement in Sri Lanka is mainly triggered by heavy rainfall. International literature is rich of works defining rainfall intensity-duration models to identify the rainfall threshold for various types of Mass move...Mass movement in Sri Lanka is mainly triggered by heavy rainfall. International literature is rich of works defining rainfall intensity-duration models to identify the rainfall threshold for various types of Mass movement. However, studies have not focused to establish a relationship between intensity and duration of rainfall in Sri Lanka. Therefore, this study focused to establish rainfall intensity-duration models to identify the rainfall threshold for mass movements in Badulla district in Sri Lanka, where forty four (44) rainfall events that resulted in same number of landslides during the last three decades were considered. Results indicate the rainfall threshold relationship fits to the log linear model of the exponential function, I = α·D-β. The constructed I-D curve revealed that short duration (54 mm/h) in rainfall events can potentially trigger the landslide. However, long-duration (>8 h) and low-intensity (<25 mm/h) in rainfall events may also trigger mass movements in Badulla. As per the results, most mass movements occur during northeast monsoons and inter-monsoons. In general, higher mean rainfall intensities trigger the debris flows, while long-duration rainfall events can trigger both landslides and debris flow. When compared to Sri Lankan mass movements triggering threshold intensities are fairly higher than the global threshold values. It confirms that within Badulla, mass movements are triggered by very high intense and/or long duration rainfalls events only. Further, time series analysis of the rainfall events shows an upward trend of extreme rainfall events, which increased landslide occurring frequency in last six (6) years.展开更多
在普通双触发巨灾看跌期权支付结构中融入基于在险价值(value at risk,VaR)的风险比率,以体现保险公司累积巨灾赔付损失对巨灾期权行权收益的影响和保险公司的风险承受水平。首先,在金融与巨灾乘积概率空间下推导出融合风险比率巨灾看...在普通双触发巨灾看跌期权支付结构中融入基于在险价值(value at risk,VaR)的风险比率,以体现保险公司累积巨灾赔付损失对巨灾期权行权收益的影响和保险公司的风险承受水平。首先,在金融与巨灾乘积概率空间下推导出融合风险比率巨灾看跌期权的定价公式;其次,基于超阈值模型(peak over threshold,POT)模型拟合我国台风的巨灾损失分布以体现巨灾损失的厚尾性特征;最后,利用蒙特卡罗模拟方法对影响巨灾看跌期权的相关因素进行敏感性分析,并与普通巨灾期权进行比较。展开更多
基金supported by the National Natural Science Foundation of China(62203283)Shandong Provincial Natural Science Foundation(ZR2022QF009,ZR2023QA063)the China Postdoctoral Science Foundation(2022M711981).
文摘Dear Editor,This letter investigates global stabilization of uncertain nonlinear systems via adaptive event-triggered output feedback.Uncertainties lie in both system nonlinearities and measurement sensitivity.To this end,a dynamic high gain is introduced to cope with the influence of large uncertainties,the unknown measurement sensitivity and the execution error,while a time-varying threshold event-triggering mechanism is constructed to effectively exclude the Zeno phenomenon.As such,the adaptive event-triggered control ensures globally bounded and convergent of system states.The design method is demonstrated using a controlled pendulum example.
基金supported by the Director Foundation of Institute of SeismologyChina Earthquake Administration(201056088)
文摘The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the Wenchuan Ms8.0 earthquake, we calculated the coulomb failure stress change. The inverted coulomb stress changes based on the Nishimura and Chenji models both show that the Lushan MT. 0 earth- quake occurred in the increased area of coulomb failure stress induced by the Wenchuan Ms8. 0 earthquake. The coulomb failure stress increased by approximately 0. 135 - 0. 152 bar in the source of the Lushan M7.0 earthquake, which is far more than the stress triggering threshold. Therefore, the Lushan M7.0 earthquake was most likely triggered by the coulomb failure stress change.
基金funded by Russian Foundation for Basic Research according to research project No.15-55-53104National Natural Science Foundation of China according to International cooperation project No.41511130032
文摘Recently published results of field and laboratory experiments on the seismic/acoustic response to injection of direct current （DC） pulses into the Earth crust or stressed rock samples raised a question on a possibility of electrical earthquake triggering. A physical mechanism of the considered phenomenon is not clear yet in view of the very low current density （10-7-10-s A/m^2） generated by the pulsed power systems at the epicenter depth （5-10 km） of local earthquakes occurred just after the current injection. The paper describes results of laboratory ＂earthquake＂ triggering by DC pulses under conditions of a spring-block model simulated the seismogenic fault. It is experimentally shown that the electric triggering of the laboratory ＂earthquake＂ （sharp slip of a movable block of the spring-block system） is possible only within a range of subcritical state of the system, when the shear stress between the movable and fixed blocks obtains 0.98-0.99 of its critical value. The threshold of electric triggering action is about 20 A/m^2 that is 7-8 orders of magnitude higher than estimated electric current density for Bishkek test site （Northern Tien Shan, Kirghizia） where the seismic response to the man-made electric action was observed. In this connection, the electric triggering phenomena may be explained by contraction of electric current in the narrow conductive areas of the faults and the corresponding increase in current density or by involving the secondary triggering mechanisms like electromagnetic stimulation of conductive fluid migration into the fault area resulted in decrease in the fault strength properties.
文摘BACKGROUND Borderline form of empty follicle syndrome is a condition in which only a few mature or immature oocytes are recovered after meticulous follicular aspiration,despite adequate ovarian response to stimulation.It is a rare phenomenon with an unclear cause.Currently,the condition still lacks effective treatment.CASE SUMMARY A patient with secondary infertility who had undergone three cycles of assisted reproductive technique(ART)is described.With regard to good follicular response,two oocytes were obtained in the first two ART cycles,but no embryo was formed.In the third ART cycle,which is the subject of this study,ovulation was induced by dual trigger of a supernormal dose of human chorionic gonadotropin(HCG)combined with a delayed oocyte retrieval approach.The method involved administration of gonadotropin-releasing hormone agonist,recombinant HCG,and urinary HCG 39 h before ovum pick-up.Ten oocytes were recovered,two out of three mature eggs were fertilized after intracytoplasmic sperm injection,resulting in two embryos that were subsequently cryopreserved.The case report guidelines have been used herein to present the first case of this novel dual trigger method.CONCLUSION This approach provides a new treatment option for patients with a similar condition in the future.This study can also inspire further investigation on the effects of variousβ-HCG serum levels 36 h after intramuscular HCG administration.
文摘Mass movement in Sri Lanka is mainly triggered by heavy rainfall. International literature is rich of works defining rainfall intensity-duration models to identify the rainfall threshold for various types of Mass movement. However, studies have not focused to establish a relationship between intensity and duration of rainfall in Sri Lanka. Therefore, this study focused to establish rainfall intensity-duration models to identify the rainfall threshold for mass movements in Badulla district in Sri Lanka, where forty four (44) rainfall events that resulted in same number of landslides during the last three decades were considered. Results indicate the rainfall threshold relationship fits to the log linear model of the exponential function, I = α·D-β. The constructed I-D curve revealed that short duration (54 mm/h) in rainfall events can potentially trigger the landslide. However, long-duration (>8 h) and low-intensity (<25 mm/h) in rainfall events may also trigger mass movements in Badulla. As per the results, most mass movements occur during northeast monsoons and inter-monsoons. In general, higher mean rainfall intensities trigger the debris flows, while long-duration rainfall events can trigger both landslides and debris flow. When compared to Sri Lankan mass movements triggering threshold intensities are fairly higher than the global threshold values. It confirms that within Badulla, mass movements are triggered by very high intense and/or long duration rainfalls events only. Further, time series analysis of the rainfall events shows an upward trend of extreme rainfall events, which increased landslide occurring frequency in last six (6) years.
文摘在普通双触发巨灾看跌期权支付结构中融入基于在险价值(value at risk,VaR)的风险比率,以体现保险公司累积巨灾赔付损失对巨灾期权行权收益的影响和保险公司的风险承受水平。首先,在金融与巨灾乘积概率空间下推导出融合风险比率巨灾看跌期权的定价公式;其次,基于超阈值模型(peak over threshold,POT)模型拟合我国台风的巨灾损失分布以体现巨灾损失的厚尾性特征;最后,利用蒙特卡罗模拟方法对影响巨灾看跌期权的相关因素进行敏感性分析,并与普通巨灾期权进行比较。
