Based on the explicit finite element(FE) method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional(2D) FE nonlinear an...Based on the explicit finite element(FE) method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional(2D) FE nonlinear analytical model for Fuzhou Basin was established.The peak ground motion acceleration(PGA) and focusing effect with depth were analyzed.Meanwhile,the results by wave propagation of one-dimensional(1D) layered medium equivalent linearization method were added for contrast.The results show that:1) PGA at different depths are obviously amplified compared to the input ground motion,amplification effect of both funnel-shaped depression and upheaval areas(based on the shape of bedrock surface) present especially remarkable.The 2D results indicate that the PGA displays a non-monotonic decreasing with depth and a greater focusing effect of some particular layers,while the 1D results turn out that the PGA decreases with depth,except that PGA at few particular depth increases abruptly; 2) To the funnel-shaped depression areas,PGA amplification effect above 8 m depth shows relatively larger,to the upheaval areas,PGA amplification effect from 15 m to 25 m depth seems more significant.However,the regularities of the PGA amplification effect could hardly be found in the rest areas; 3) It appears a higher regression rate of PGA amplification coefficient with depth when under a smaller input motion; 4) The frequency spectral characteristic of input motion has noticeable effects on PGA amplification tendency.展开更多
The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The ...The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The formation of acousticmetamaterial is designed into a cylindrical structure with three layers of ludox,cork and fluid rubber,which can produce a focusingphenomenon when acoustic waves propagate in air.For these strange phenomena,a scientific description is given theorietically.It can also be concluded that when the frequency of the incident acoustic wave increases?the number of peripheral bandsoutside the focusing poles will increase periodically.Besides,there are numerous groups of multipolar focusing phenomena inhigh frequency.The design of this acoustic metamaterial is successful through theorietical and experimental verification,therefore,it can be applied to acoustic communication and test.展开更多
We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach.With increasing laser intensity,the Coulomb focusing（CF） effects are found to become stron...We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach.With increasing laser intensity,the Coulomb focusing（CF） effects are found to become stronger in both parallel and perpendicular directions with respect to the polarization plane.The dependence of CF effects on tunnel exit,initial transverse momentum distribution and laser electric field is analyzed.It was revealed that the effects of tunnel exit are most prominent with variation of the laser intensity,and the other two factors both play non-negligible roles.Our results provide a deeper insight to the recent experiments of Coulomb asymmetry[Shafir D,et al.,2013 Phys.Rev.Lett.111 023005 and Li M,et al,2013 Phys.Rev.Lett.111 023006].展开更多
The spreading effect of atmospheric pressure microplasma jets(APμPJ)on the surface of materials will increase the etching area,and controlling the diameter of the jet can improve the precision of surface treatment.In...The spreading effect of atmospheric pressure microplasma jets(APμPJ)on the surface of materials will increase the etching area,and controlling the diameter of the jet can improve the precision of surface treatment.In this work,a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen(N_(2))shielding gas on helium(He)from gas dynamics.In addition,by etching the polyethylene terephthalate fllm,the relationship between the etching effect and aerodynamic analysis is verifled.The simulation results are similar to the experimental results,indicating that N2 shielding gas has a focusing effect which is related to the N_(2)flow rate,distance difference between the inner and outer tubes,and outer tube nozzle diameter.It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.展开更多
Ischemic stroke is a leading cause of death and has a remarkable social and economical impact, which rises with the increasing age of the industrial population. Unfortunately, treatment strat- egies for cerebral ische...Ischemic stroke is a leading cause of death and has a remarkable social and economical impact, which rises with the increasing age of the industrial population. Unfortunately, treatment strat- egies for cerebral ischemia still remain very limited. Acute reper- fusion therapies with either systemic thrombolysis using rt-PA （recombinant tissue plasminogen activator） or interventional recanalization procedures were shown to be highly effective. In addition, there is also a long-existing concept to modulate stroke-associated pathophysiological events such as exitotox- icity, peri-infarct depolarizations, apoptosis and inflammation （Dirnagl et al., 1999）.展开更多
Plasma-based optical elements can withstand laser intensities several orders of magnitude higher than traditional optical elements,making them highly promising for manipulating relativistic intensity laser pulses.In t...Plasma-based optical elements can withstand laser intensities several orders of magnitude higher than traditional optical elements,making them highly promising for manipulating relativistic intensity laser pulses.In this work,we propose and demonstrate a novel microstructured plasma target,inspired by the design of traditional Fresnel zone plates.The specific target structure causes diffraction of the input laser at each zone,resulting in constructive interference and facilitating effective focusing of the input laser pulse.Three-dimensional particle-in-cell simulation results show that the microstructured plasma target can focus Gaussian laser pulses with an intensity of the order of 10^(22) W/cm^(2)to an intensity exceeding 10^(24) W/cm^(2)with the laser focus spot size approaching the diffraction limit of-0.73μm and laser fluence enhancement by a factor of 46.It is also found that when the microstructured plasma target is modified into a reflective element,laser intensities up to 10^(25) W/cm^(2)may be achieved.This extremely high-intensity tightly focused laser pulse can trigger intense photon radiation when interacting with targets,(e.g.,wire plasma targets),with potential applications in laboratory astrophysics,as well as providing the opportunity to explore phenomena such as vacuum birefringence and quantum electrodynamical cascades.展开更多
The damage properties of Focused Ion Beam(FIB) milling Si3N4 thin film are investigated by the detailed analyzing images of nanoholes and simulation of Monte Carlo. The damage depth in the Si3N4 thin film for two diff...The damage properties of Focused Ion Beam(FIB) milling Si3N4 thin film are investigated by the detailed analyzing images of nanoholes and simulation of Monte Carlo. The damage depth in the Si3N4 thin film for two different ion species(Gallium and Arsenic) under various parameters(ion energy, angle of incidence) are investigated by Monte Carlo method. The simulations show the damage depth increases with the increasing ion energy, the damage depth is dependent on the angle of incident ion, the curves of the damage depth for Ga ion and As ion at 30 keV nearly superpose, while the damage depth for Ga with 90 keV ion is more than that for As ion with the same energy.展开更多
The thermal effects induced by a moderate intensity focused ultrasound and enhanced by combined laser pulses for bio-tissues and tissue-phantom are studied experimentally and theoretically. At first, the heating effec...The thermal effects induced by a moderate intensity focused ultrasound and enhanced by combined laser pulses for bio-tissues and tissue-phantom are studied experimentally and theoretically. At first, the heating effects of bio-tissues and tissue-phantom induced by ultrasound and enhanced by laser are measured experimentally. The heating processes induced by attenuations of focused ultrasonic waves and cavitation effects of the focused ultrasound and combined laser are analyzed theoretically. By analyzing the mechanisms of these effects, it is found that the laser nucleation makes the cavitation bubble generation more easily, which can effectively enhance the ultrasonic cavitation effects, and then enhance the thermal effects of the samples. On the other hand, to evaluate quantitatively the heating processes induced by the focused ultrasound and enhanced by the pulsed laser, by fitting the theoretical calculations to the experimental results, the corresponding cavitation bubbles and rising temperatures induced by the focused ultrasound with and without laser can be estimated approximately.展开更多
基金Project(2011CB013601) supported by the National Basic Research Program of ChinaProject(51378258) supported by the National Natural Science Foundation of China
文摘Based on the explicit finite element(FE) method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional(2D) FE nonlinear analytical model for Fuzhou Basin was established.The peak ground motion acceleration(PGA) and focusing effect with depth were analyzed.Meanwhile,the results by wave propagation of one-dimensional(1D) layered medium equivalent linearization method were added for contrast.The results show that:1) PGA at different depths are obviously amplified compared to the input ground motion,amplification effect of both funnel-shaped depression and upheaval areas(based on the shape of bedrock surface) present especially remarkable.The 2D results indicate that the PGA displays a non-monotonic decreasing with depth and a greater focusing effect of some particular layers,while the 1D results turn out that the PGA decreases with depth,except that PGA at few particular depth increases abruptly; 2) To the funnel-shaped depression areas,PGA amplification effect above 8 m depth shows relatively larger,to the upheaval areas,PGA amplification effect from 15 m to 25 m depth seems more significant.However,the regularities of the PGA amplification effect could hardly be found in the rest areas; 3) It appears a higher regression rate of PGA amplification coefficient with depth when under a smaller input motion; 4) The frequency spectral characteristic of input motion has noticeable effects on PGA amplification tendency.
基金National Natural Science Foundation of China(No.61671414)Natural Science Foundation for Young Scientists of Shanxi Province,China(No.201601D202035)
文摘The acoustic focusing effect of metamaterial has a wide range of applications in medicine,acoustic imaging,signal detection,etc.This paper presents an acoustic metamaterial applied to the acoustic focusing effect.The formation of acousticmetamaterial is designed into a cylindrical structure with three layers of ludox,cork and fluid rubber,which can produce a focusingphenomenon when acoustic waves propagate in air.For these strange phenomena,a scientific description is given theorietically.It can also be concluded that when the frequency of the incident acoustic wave increases?the number of peripheral bandsoutside the focusing poles will increase periodically.Besides,there are numerous groups of multipolar focusing phenomena inhigh frequency.The design of this acoustic metamaterial is successful through theorietical and experimental verification,therefore,it can be applied to acoustic communication and test.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11547218,11564020,and 11504314)
文摘We investigate atomic above-threshold ionization in elliptically polarized strong laser fields with a semiclassical approach.With increasing laser intensity,the Coulomb focusing（CF） effects are found to become stronger in both parallel and perpendicular directions with respect to the polarization plane.The dependence of CF effects on tunnel exit,initial transverse momentum distribution and laser electric field is analyzed.It was revealed that the effects of tunnel exit are most prominent with variation of the laser intensity,and the other two factors both play non-negligible roles.Our results provide a deeper insight to the recent experiments of Coulomb asymmetry[Shafir D,et al.,2013 Phys.Rev.Lett.111 023005 and Li M,et al,2013 Phys.Rev.Lett.111 023006].
基金supported by National Natural Science Foundation of China(No.51905002)Anhui Provincial Natural Science Foundation(Nos.2008085QE230,2108085ME174)+2 种基金Open Project of Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials(No.GFST2021KF06)Open Project of Anhui Province Key Laboratory of Special and Heavy Load Robot(No.TZJQRO03-2021)Open Project of Anhui Province Engineering Laboratory of Intelligent Demolition Equipment(No.APELIDE2021B001)。
文摘The spreading effect of atmospheric pressure microplasma jets(APμPJ)on the surface of materials will increase the etching area,and controlling the diameter of the jet can improve the precision of surface treatment.In this work,a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen(N_(2))shielding gas on helium(He)from gas dynamics.In addition,by etching the polyethylene terephthalate fllm,the relationship between the etching effect and aerodynamic analysis is verifled.The simulation results are similar to the experimental results,indicating that N2 shielding gas has a focusing effect which is related to the N_(2)flow rate,distance difference between the inner and outer tubes,and outer tube nozzle diameter.It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.
文摘Ischemic stroke is a leading cause of death and has a remarkable social and economical impact, which rises with the increasing age of the industrial population. Unfortunately, treatment strat- egies for cerebral ischemia still remain very limited. Acute reper- fusion therapies with either systemic thrombolysis using rt-PA （recombinant tissue plasminogen activator） or interventional recanalization procedures were shown to be highly effective. In addition, there is also a long-existing concept to modulate stroke-associated pathophysiological events such as exitotox- icity, peri-infarct depolarizations, apoptosis and inflammation （Dirnagl et al., 1999）.
基金supported by the National Natural Science Foundation of China(Grant Nos.12375244 and 12135009)the Natural Science Foundation of Hunan Province of China(Grant No.2025JJ30002).
文摘Plasma-based optical elements can withstand laser intensities several orders of magnitude higher than traditional optical elements,making them highly promising for manipulating relativistic intensity laser pulses.In this work,we propose and demonstrate a novel microstructured plasma target,inspired by the design of traditional Fresnel zone plates.The specific target structure causes diffraction of the input laser at each zone,resulting in constructive interference and facilitating effective focusing of the input laser pulse.Three-dimensional particle-in-cell simulation results show that the microstructured plasma target can focus Gaussian laser pulses with an intensity of the order of 10^(22) W/cm^(2)to an intensity exceeding 10^(24) W/cm^(2)with the laser focus spot size approaching the diffraction limit of-0.73μm and laser fluence enhancement by a factor of 46.It is also found that when the microstructured plasma target is modified into a reflective element,laser intensities up to 10^(25) W/cm^(2)may be achieved.This extremely high-intensity tightly focused laser pulse can trigger intense photon radiation when interacting with targets,(e.g.,wire plasma targets),with potential applications in laboratory astrophysics,as well as providing the opportunity to explore phenomena such as vacuum birefringence and quantum electrodynamical cascades.
基金Science Foundation of Yunnan Province , China(2004A00229 M)
文摘The damage properties of Focused Ion Beam(FIB) milling Si3N4 thin film are investigated by the detailed analyzing images of nanoholes and simulation of Monte Carlo. The damage depth in the Si3N4 thin film for two different ion species(Gallium and Arsenic) under various parameters(ion energy, angle of incidence) are investigated by Monte Carlo method. The simulations show the damage depth increases with the increasing ion energy, the damage depth is dependent on the angle of incident ion, the curves of the damage depth for Ga ion and As ion at 30 keV nearly superpose, while the damage depth for Ga with 90 keV ion is more than that for As ion with the same energy.
基金supported by the National Natural Science Foundation of China(11304160)Special Funds for Quality Supervision,Inspection and Quarantine Research in Public Interest of China(201510068)
文摘The thermal effects induced by a moderate intensity focused ultrasound and enhanced by combined laser pulses for bio-tissues and tissue-phantom are studied experimentally and theoretically. At first, the heating effects of bio-tissues and tissue-phantom induced by ultrasound and enhanced by laser are measured experimentally. The heating processes induced by attenuations of focused ultrasonic waves and cavitation effects of the focused ultrasound and combined laser are analyzed theoretically. By analyzing the mechanisms of these effects, it is found that the laser nucleation makes the cavitation bubble generation more easily, which can effectively enhance the ultrasonic cavitation effects, and then enhance the thermal effects of the samples. On the other hand, to evaluate quantitatively the heating processes induced by the focused ultrasound and enhanced by the pulsed laser, by fitting the theoretical calculations to the experimental results, the corresponding cavitation bubbles and rising temperatures induced by the focused ultrasound with and without laser can be estimated approximately.
