Aim To assess simultaneously various risk states of a system. Methods\ Using the catastrophe and fuzzy theory, the energy and uncertainty in a system are set as two control variables and the function of the system is...Aim To assess simultaneously various risk states of a system. Methods\ Using the catastrophe and fuzzy theory, the energy and uncertainty in a system are set as two control variables and the function of the system is used as the state variable for analysis. Results and Conclusion\ A risk analysis model named the cusp model is presented. Various states regarding the safety of the system such as the accident state, no accident state and miss state can be represented at will on the cusp model.展开更多
A simplified mechanical model of pillar-hang wall was established in asymmetric mining and instability of the system was discussed by means of potential energy principle and cusp catastrophe theory. The necessary-suff...A simplified mechanical model of pillar-hang wall was established in asymmetric mining and instability of the system was discussed by means of potential energy principle and cusp catastrophe theory. The necessary-sufficient condition and the jump value of displacement of pillar and the released energy expressions were derived, which established foundation for quantifying of the instability of system. The results show that instability of the system is related to load and its stiffness distribution. The critical load increases with the increasing relative stiffness, and the system is more stable. On the contrary, the instability of system is likely to occur, and the released energy is larger in instability process, and the harm is more tremendous accordingly. Furthermore, an example was calculated, and the estimated results are in good agreement with the practical experience, which provide basis for mining order and arranging stope.展开更多
A method of slope reliability analysis was developed by imposing a state equation on the limit equilibrium theory, given the basis of a fixed safety factor technique. Among the many problems of reliability analysis, t...A method of slope reliability analysis was developed by imposing a state equation on the limit equilibrium theory, given the basis of a fixed safety factor technique. Among the many problems of reliability analysis, the most important problem is to find a performance function. We have created a new method of building a limit state equation for planar slip surfaces by applying the mathematical cusp catastrophe theory. This new technique overcomes the defects in the traditional rigid limit equilibrium theory and offers a new way for studying the reliability problem of planar slip surfaces. Consequently, we applied the technique to a case of an open-pit mine and compared our results with that of the traditional approach. From the results we conclude that both methods are essentially consistent, but the reliability index calculated by the traditional model is lower than that from the catastrophic model. The catastrophe model takes into consideration two possible situations of a slope being in the limit equilibrium condition, i.e., it may or may not slip. In the traditional method, however, a slope is definitely considered as slipping when it meets the condition of a limit equilibrium. We conclude that the catastrophe model has more actual and instructive importance compared to the traditional model.展开更多
The energy transfer between ions （protons） and low frequency waves （LFWs） in the frequency range f1 from 0.3 to 10 Hz is observed by Cluster crossing the high-altitude polar cusp. The energy transfer between low f...The energy transfer between ions （protons） and low frequency waves （LFWs） in the frequency range f1 from 0.3 to 10 Hz is observed by Cluster crossing the high-altitude polar cusp. The energy transfer between low frequency waves and ions has two means. One is that the energy is transferred from low frequency waves to ions and ions energy increases, The other is that the energy is transferred from ions to low frequency waves and the ion energy decreases. lon gyratory motion plays an important role in the energy transfer processes. The electromagnetic field of f1 LFWs can accelerate or decelerate protons along the direction of ambient magnetic field and warm or refrigerate protons in the parallel and perpendicular directions of ambient magnetic field, The peak values of proton number densities have the corresponding peak values of electromagnetic energy of low-frequency waves. This implies that the kinetic Alfven waves and solitary kinetic Alfven waves possibly exist in the high-altitude cusp region.展开更多
Background: Perimembranous ventricular septal defect combined with right coronary cusp bulge generally should be treated with surgical thoracotomy, owing to the potential aortic regurgitation. However, the minimally i...Background: Perimembranous ventricular septal defect combined with right coronary cusp bulge generally should be treated with surgical thoracotomy, owing to the potential aortic regurgitation. However, the minimally invasive method of transcatheter closure has always attracted the attention of cardiologists and patients. The present study aimed to apply transcatheter occlusion in treating ventricular septal defect with right coronary cusp bulge and further evaluate the clinical effect through follow-up. Materials and methods: A total of 40 children diagnosed as having a ventricular septal defect with right coronary cusp bulge, examined using transthoracic echocardiography and cardiovascular angiography, were enrolled in this study. The ventricular septal defects were closed by placing occluders through transcatheter occlusion treatment. During the operation process, the children underwent angiography and transthoracic echocardiography examinations to check the position of the occlude and the extent of aortic regurgitation. The influence of occlusion on the conduction system was evaluated using a surface electrocardiogram. The children were followed up after their procedures. Results: All 40 patients were immediately and successfully occluded. Three patients with filament residual shunts were observed during the operations. No major surgical complications occurred during the perioperative period. During the follow-up period, the positions of all the occluders were good, the residual shunts in the three patients disappeared, and no new or aggravated aortic regurgitation occurred. Electrocardiogram did not reveal any atrioventricular blocks. Only one patient suffered from an incomplete right bundle branch block. Conclusions: Children diagnosed with ventricular septal defect combined with right coronary cusp bulge could be considered for transcatheter occlusion. With appropriate indications and methods, the effect may be favorable.展开更多
A Chinese Antarctic Magnetometer （CAM） chain from Zhongshan Station （ZHS） to Dome-A （DMA） has been established since February 2009. A regular magnetometer is operated at ZHS, and four low power magnetometers are...A Chinese Antarctic Magnetometer （CAM） chain from Zhongshan Station （ZHS） to Dome-A （DMA） has been established since February 2009. A regular magnetometer is operated at ZHS, and four low power magnetometers are operated along the interior route from ZHS to DMA in the cusp latitude, extending over a distance of 1260 km. These stations fill an important void in the Antarctic magnetometer network. Furthermore, the CAM chain is magnetically conjugated with the Arctic region reaching from the Svalbard archipelago to Daneborg, on the east coast of Greenland. Conjugate measurements using the Arctic and Antarctic magnetometers provide excellent opportunities to investigate phenomena related to the coupling of the solar wind to the magnetosphere and ionosphere, such as magnetic impulse events, flux transfer events, traveling convection vortices and ultra-low frequency waves.展开更多
Magnetic mirror used as an efficient tool to confine plasma has been widely adopted in many different areas especially in recent cusped field thrusters. In order to check the influence of magnetic mirror effect on the...Magnetic mirror used as an efficient tool to confine plasma has been widely adopted in many different areas especially in recent cusped field thrusters. In order to check the influence of magnetic mirror effect on the plasma distribution in a cusped field thruster, three different radii of the discharge channel(6 mm, 4 mm, and 2 mm) in a cusped field thruster are investigated by using Particle-in-Cell Plus Monte Carlo(PIC-MCC) simulated method, under the condition of a fixed axial length of the discharge channel and the same operating parameters. It is found that magnetic cusps inside the small radius discharge channel cannot confine electrons very well. Thus, the electric field is hard to establish. With the reduction of the discharge channel’s diameter, more electrons will escape from cusps to the centerline area near the anode due to a lower magnetic mirror ratio. Meanwhile, the leak width of the cusped magnetic field will increase at the cusp. By increasing the magnetic field strength in a small radius model of a cusped field thruster, the negative effect caused by the weak magnetic mirror effect can be partially compensated. Therefore, according to engineering design, the increase of magnetic field strength can contribute to obtaining a good performance, when the radial distance between the magnets and the inner surface of the discharge channel is relatively big.展开更多
The cylindrical Hall thruster has the good prospect of serving as a miniaturized electric propulsion device.A 2 D-3 V particle-in-cell plus Monte Carlo（PIC-MCC） method is used to study the effect of the magnetic cus...The cylindrical Hall thruster has the good prospect of serving as a miniaturized electric propulsion device.A 2 D-3 V particle-in-cell plus Monte Carlo（PIC-MCC） method is used to study the effect of the magnetic cusp on discharge characteristics of a cylindrical Hall thruster.The simulation results show that the main ionization region and the main potential drop of the thruster are located at the upstream of the discharge channel.When the magnetic cusp moves toward the anode side,the main ionization region is compressed and weakened,moving upstream correspondingly.The ionization near the cusp is enhanced,and the interaction between the plasma and the wall increases.The simulation results suggest that the magnetic cusp should be located near the channel exit.展开更多
文摘Aim To assess simultaneously various risk states of a system. Methods\ Using the catastrophe and fuzzy theory, the energy and uncertainty in a system are set as two control variables and the function of the system is used as the state variable for analysis. Results and Conclusion\ A risk analysis model named the cusp model is presented. Various states regarding the safety of the system such as the accident state, no accident state and miss state can be represented at will on the cusp model.
文摘A simplified mechanical model of pillar-hang wall was established in asymmetric mining and instability of the system was discussed by means of potential energy principle and cusp catastrophe theory. The necessary-sufficient condition and the jump value of displacement of pillar and the released energy expressions were derived, which established foundation for quantifying of the instability of system. The results show that instability of the system is related to load and its stiffness distribution. The critical load increases with the increasing relative stiffness, and the system is more stable. On the contrary, the instability of system is likely to occur, and the released energy is larger in instability process, and the harm is more tremendous accordingly. Furthermore, an example was calculated, and the estimated results are in good agreement with the practical experience, which provide basis for mining order and arranging stope.
基金financial support from Changjiang Scholars and Innovative Research Team in University, and research project of ‘SUST Spring Bud’
文摘A method of slope reliability analysis was developed by imposing a state equation on the limit equilibrium theory, given the basis of a fixed safety factor technique. Among the many problems of reliability analysis, the most important problem is to find a performance function. We have created a new method of building a limit state equation for planar slip surfaces by applying the mathematical cusp catastrophe theory. This new technique overcomes the defects in the traditional rigid limit equilibrium theory and offers a new way for studying the reliability problem of planar slip surfaces. Consequently, we applied the technique to a case of an open-pit mine and compared our results with that of the traditional approach. From the results we conclude that both methods are essentially consistent, but the reliability index calculated by the traditional model is lower than that from the catastrophic model. The catastrophe model takes into consideration two possible situations of a slope being in the limit equilibrium condition, i.e., it may or may not slip. In the traditional method, however, a slope is definitely considered as slipping when it meets the condition of a limit equilibrium. We conclude that the catastrophe model has more actual and instructive importance compared to the traditional model.
基金Supported by the National Natural Science Foundation of China under Grant No 40390150, and the Postdoctoral Science Foundation of High Education of China.
文摘The energy transfer between ions （protons） and low frequency waves （LFWs） in the frequency range f1 from 0.3 to 10 Hz is observed by Cluster crossing the high-altitude polar cusp. The energy transfer between low frequency waves and ions has two means. One is that the energy is transferred from low frequency waves to ions and ions energy increases, The other is that the energy is transferred from ions to low frequency waves and the ion energy decreases. lon gyratory motion plays an important role in the energy transfer processes. The electromagnetic field of f1 LFWs can accelerate or decelerate protons along the direction of ambient magnetic field and warm or refrigerate protons in the parallel and perpendicular directions of ambient magnetic field, The peak values of proton number densities have the corresponding peak values of electromagnetic energy of low-frequency waves. This implies that the kinetic Alfven waves and solitary kinetic Alfven waves possibly exist in the high-altitude cusp region.
基金supported by the National Science Foundation of China(Grant number 81470443)
文摘Background: Perimembranous ventricular septal defect combined with right coronary cusp bulge generally should be treated with surgical thoracotomy, owing to the potential aortic regurgitation. However, the minimally invasive method of transcatheter closure has always attracted the attention of cardiologists and patients. The present study aimed to apply transcatheter occlusion in treating ventricular septal defect with right coronary cusp bulge and further evaluate the clinical effect through follow-up. Materials and methods: A total of 40 children diagnosed as having a ventricular septal defect with right coronary cusp bulge, examined using transthoracic echocardiography and cardiovascular angiography, were enrolled in this study. The ventricular septal defects were closed by placing occluders through transcatheter occlusion treatment. During the operation process, the children underwent angiography and transthoracic echocardiography examinations to check the position of the occlude and the extent of aortic regurgitation. The influence of occlusion on the conduction system was evaluated using a surface electrocardiogram. The children were followed up after their procedures. Results: All 40 patients were immediately and successfully occluded. Three patients with filament residual shunts were observed during the operations. No major surgical complications occurred during the perioperative period. During the follow-up period, the positions of all the occluders were good, the residual shunts in the three patients disappeared, and no new or aggravated aortic regurgitation occurred. Electrocardiogram did not reveal any atrioventricular blocks. Only one patient suffered from an incomplete right bundle branch block. Conclusions: Children diagnosed with ventricular septal defect combined with right coronary cusp bulge could be considered for transcatheter occlusion. With appropriate indications and methods, the effect may be favorable.
基金supported by the CNSF project(Grant nos.41574164,41431072)the International Cooperation Project(Grant no.IC201509)of the Chinese Arctic and Antarctic Administration,State Oceanic Administration
文摘A Chinese Antarctic Magnetometer （CAM） chain from Zhongshan Station （ZHS） to Dome-A （DMA） has been established since February 2009. A regular magnetometer is operated at ZHS, and four low power magnetometers are operated along the interior route from ZHS to DMA in the cusp latitude, extending over a distance of 1260 km. These stations fill an important void in the Antarctic magnetometer network. Furthermore, the CAM chain is magnetically conjugated with the Arctic region reaching from the Svalbard archipelago to Daneborg, on the east coast of Greenland. Conjugate measurements using the Arctic and Antarctic magnetometers provide excellent opportunities to investigate phenomena related to the coupling of the solar wind to the magnetosphere and ionosphere, such as magnetic impulse events, flux transfer events, traveling convection vortices and ultra-low frequency waves.
基金supported by the National Natural Science Foundation of China(Grant No.51006028)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51121004)
文摘Magnetic mirror used as an efficient tool to confine plasma has been widely adopted in many different areas especially in recent cusped field thrusters. In order to check the influence of magnetic mirror effect on the plasma distribution in a cusped field thruster, three different radii of the discharge channel(6 mm, 4 mm, and 2 mm) in a cusped field thruster are investigated by using Particle-in-Cell Plus Monte Carlo(PIC-MCC) simulated method, under the condition of a fixed axial length of the discharge channel and the same operating parameters. It is found that magnetic cusps inside the small radius discharge channel cannot confine electrons very well. Thus, the electric field is hard to establish. With the reduction of the discharge channel’s diameter, more electrons will escape from cusps to the centerline area near the anode due to a lower magnetic mirror ratio. Meanwhile, the leak width of the cusped magnetic field will increase at the cusp. By increasing the magnetic field strength in a small radius model of a cusped field thruster, the negative effect caused by the weak magnetic mirror effect can be partially compensated. Therefore, according to engineering design, the increase of magnetic field strength can contribute to obtaining a good performance, when the radial distance between the magnets and the inner surface of the discharge channel is relatively big.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11505041 and 51776047)
文摘The cylindrical Hall thruster has the good prospect of serving as a miniaturized electric propulsion device.A 2 D-3 V particle-in-cell plus Monte Carlo（PIC-MCC） method is used to study the effect of the magnetic cusp on discharge characteristics of a cylindrical Hall thruster.The simulation results show that the main ionization region and the main potential drop of the thruster are located at the upstream of the discharge channel.When the magnetic cusp moves toward the anode side,the main ionization region is compressed and weakened,moving upstream correspondingly.The ionization near the cusp is enhanced,and the interaction between the plasma and the wall increases.The simulation results suggest that the magnetic cusp should be located near the channel exit.
