Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little...Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little is known about the impact of the rate of current change on working memory.In this study,we aimed to investigate the effects of two types of tACS with different rates of current change on working memory performance and brain activity.We applied a randomized,single-blind design and divided 81 young participants who received triangular wave tACS,sinusoidal wave tACS,or sham stimulation into three groups.Participants performed n-back tasks,and electroencephalograms were recorded before,during,and after active or sham stimulation.Compared to the baseline,working memory performance(accuracy and response time)improved after stimulation under all stimulation conditions.According to drift-diffusion model analysis,triangular wave tACS significantly increased the efficiency of non-target information processing.In addition,compared with sham conditions,triangular wave tACS reduced alpha power oscillations in the occipital lobe throughout the encoding period,while sinusoidal wave tACS increased theta power in the central frontal region only during the later encoding period.The brain network connectivity results showed that triangular wave tACS improved the clustering coefficient,local efficiency,and node degree intensity in the early encoding stage,and these parameters were positively correlated with the non-target drift rate and decision starting point.Our findings on how tACS modulates working memory indicate that triangular wave tACS significantly enhances brain network connectivity during the early encoding stage,demonstrating an improvement in the efficiency of working memory processing.In contrast,sinusoidal wave tACS increased the theta power during the later encoding stage,suggesting its potential critical role in late-stage information processing.These findings provide valuable insights into the potential mechanisms by which tACS modulates working memory.展开更多
Surface irregularities,such as hills and ridges,can significantly amplify ground motion caused by earthquakes.Therefore,in this study,we propose an analytical solution model to investigate the interaction between an a...Surface irregularities,such as hills and ridges,can significantly amplify ground motion caused by earthquakes.Therefore,in this study,we propose an analytical solution model to investigate the interaction between an asymmetric triangular hill on Earth and SH waves.Firstly,based on the development of wave functions and regional matching techniques,we introduce a semi-circular artificial auxiliary boundary,dividing the solution model into a semi-infinite body containing a semi-circular depression and an asymmetric fan-shaped region.Secondly,we derive the domain function form applicable to solving asymmetric problems.Utilizing the theory of complex variables,we establish a well-posed matrix for solving domain functions within the same coordinate system.Numerical results demonstrate that the scattering of SH waves by a protuberance is jointly influenced by the geometric parameters of the hill and the angle of incidence.Additionally,the frequency of the incident wave also has a certain degree of impact on the displacement amplitude.This study elucidates the scattering mechanism of SH waves by complex boundaries,providing a theoretical reference for building site selection and seismic design.In practical problems,the asymmetric assumption is more applicable than the symmetry assumption.展开更多
This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stabl...This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stable configuration is essential for the continuous observation of gravitational waves(GWs).However,the motion near the collinear libration points is highly unstable.This problem is examined by output regulation theory.Using the tracking aspect,the equilateral triangular array formation is established in two periods and the fuel consumption is calculated.Furthermore,the natural evolution of the formation without control input is analyzed,and the effective stability duration is quantified to determine the timing of control interventions.Finally,to observe the GWs in same direction with different frequency bands,scale reconfiguration is employed.展开更多
To address the problem of subdividing inflexible rectangular grid models and their poor definition of velocity interfaces,we propose a complex structure triangular net for a minimum traveltime ray tracing global algor...To address the problem of subdividing inflexible rectangular grid models and their poor definition of velocity interfaces,we propose a complex structure triangular net for a minimum traveltime ray tracing global algorithm.Our procedure is：（1） Subdivide a triangle grid based on the Delaunay triangular subdivision criterion and the relationships of the points,lines,and the surfaces in the subdividing area.（2） Define the topology relationships and related concepts of triangular unit ray tracing.（3） The source point and wave arrival points at any time compose the propagating plane wave and the minimum traveltime and secondary source positions are calculated during the plane wave propagation.We adopt the hyperbolic approximation global algorithm for secondary source retrieving.（4） By minimum traveltime ray tracing,collect the path from receiver to source points with the neighborhood point＇s traveltime and the direction of the secondary source.Numerical simulation examples are given to test the algorithm.The results show that the triangular net ray tracing method demonstrates model subdivision flexibility,precise velocity discontinuity interfaces,and accurate computations.展开更多
In this paper, antiplane response of an isosceles triangular hill to incident SH waves is studied based on the method of complex function and by using moving coordinate system. The standing wave function, which can sa...In this paper, antiplane response of an isosceles triangular hill to incident SH waves is studied based on the method of complex function and by using moving coordinate system. The standing wave function, which can satisfy the governing equation and boundary condition, is provided. Furthermore, numerical examples are presented; the influences of wave number and angle of the incident waves and the angle of the hill’s peak on ground motion are discussed.展开更多
The influence of local landforms on ground motion is an important problem. The antiplane response of a scalene triangular hill to incident SH waves is studied in this paper by using a complex function, moving coordina...The influence of local landforms on ground motion is an important problem. The antiplane response of a scalene triangular hill to incident SH waves is studied in this paper by using a complex function, moving coordinates and auxiliary functions. First, the model is divided into two domains： a scalene triangular hill with a semi-circular bottom; and a half space with a semi-circular canyon. Wave functions that satisfy the zero-stress condition at the triangular wedges and at the horizontal surface are constructed in both domains. Then, considering the displacement continuity and stress equilibrium, algebraic equations are established. Finally, numerical examples are provided to illustrate the influence of the geometry of the hill and the characteristics of the incident waves on the ground motions.展开更多
Damage depth is an important dynamic parameter for describing the degree of material damage and is also a key fundamental issue in the field of impact compression technology.The present work is dedicated to the damage...Damage depth is an important dynamic parameter for describing the degree of material damage and is also a key fundamental issue in the field of impact compression technology.The present work is dedicated to the damage depth of shock-melted metal in microspall under triangular wave loading,and an improved model of damage depth considering the material's compressibility and relative movement is proposed.The damage depth obtained from the proposed model is in good agreement with the laser-driven shock loading experiment.Compared with the previous model,the proposed model can predict the damage depth of shock-melted metal in microspall more accurately.Furthermore,two-groups of the smoothed particle hydrodynamics(SPH)simulations are carried out to investigate the effects of peak stress and decay length of the incident triangular wave on the damage depth,respectively.As the decay length increases,the damage depth increases linearly.As the peak stress increases,the damage depth increases nonlinearly,and the increase in damage depth gradually slows down.The results of the SPH simulations adequately reproduce the results of the proposed model in terms of the damage depth.Finally,it is found that the threshold stress criterion can reflect the macroscopic characteristics of microspall of melted metal.展开更多
Scattering of SH-waves on the triangular hill joined by semi-cylindrical canyon in half-space is studied using the method of complex function and moving coordinates. The model being studied is divided into two domains...Scattering of SH-waves on the triangular hill joined by semi-cylindrical canyon in half-space is studied using the method of complex function and moving coordinates. The model being studied is divided into two domains. The wave functions satisfying the required condition at each wedge are constructed in each equation. The equations are solved with Fourier expansion. Numerical results are provided to discuss the influence of scattering of SH-waves.展开更多
Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach. In this paper, the propagation of elastic waves in a two-dirnensional hybrid triangular lat...Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach. In this paper, the propagation of elastic waves in a two-dirnensional hybrid triangular lattice structure consisting of stainless steel cylinders in air is investigated theoretically. The band structure is calculated with the plane wave expansion （PWE） method. The hybrid triangular Bravais lattice is formed by two kinds of triangular lattices. Different from ordinary triangular lattices, the band gap opens at low frequency （between the first and the second bands） regime because of lifting the bands degeneracy at high symmetry points of the Brillouin zone. The location and width of the band gaps can be tuned by the position of the additional rods.展开更多
Internal solitary waves have been found to disintegrate into a series of solitons over variablebathymetry, with important applications for offshore engineering. Considering realisticbackground stratification in the So...Internal solitary waves have been found to disintegrate into a series of solitons over variablebathymetry, with important applications for offshore engineering. Considering realisticbackground stratification in the South China Sea, internal solitary waves propagating over a stepare studied here. By assuming disintegrated solitons propagate independently, a theoreticalmodel, namely a triangular temporal-distribution law based on the Korteweg–de Vries theory, isproposed to describe the fission process of internal solitary waves undergoing disintegration. Aparameter is then introduced to quantify the accuracy of the theoretical model. The resultsindicate that the triangular law predicts the fission process better for a longer travelling distanceand a larger amplitude of internal solitary waves.展开更多
In this paper, based on new auxiliary nonlinear ordinary differential equation with a sixtb-aegree nonnneal term, we study the （2＋l ）-dimensional Davey-Stewartson equation and new types of travelling wave solutions...In this paper, based on new auxiliary nonlinear ordinary differential equation with a sixtb-aegree nonnneal term, we study the （2＋l ）-dimensional Davey-Stewartson equation and new types of travelling wave solutions are obtained, which include new bell and kink profile solitary wave solutions, triangular periodic wave solutions, and singular solutions. The method used here can be also extended to many other nonlinear partial differential equations.展开更多
基金supported by the Key-Area Research and Development Program of Guangdong Province(2023B0303030002)the Beijing Natural Science Foundation(IS23114,7242274)+4 种基金the China Postdoctoral Science Foundation(2023TQ0027 and 2024M754099)the STI 2030-Major Projects(2022ZD0208500)the National Natural Science Foundation of China(62336002,82071912,62406025,82202291,62373056,62306035)the Beijing Nova Program(20230484465)the Shenzhen Basic Research Program(JCYJ20241202124804007).
文摘Working memory is an executive memory process that includes encoding,maintenance,and retrieval.These processes can be modulated by transcranial alternating current stimulation(tACS)with sinusoidal waves.However,little is known about the impact of the rate of current change on working memory.In this study,we aimed to investigate the effects of two types of tACS with different rates of current change on working memory performance and brain activity.We applied a randomized,single-blind design and divided 81 young participants who received triangular wave tACS,sinusoidal wave tACS,or sham stimulation into three groups.Participants performed n-back tasks,and electroencephalograms were recorded before,during,and after active or sham stimulation.Compared to the baseline,working memory performance(accuracy and response time)improved after stimulation under all stimulation conditions.According to drift-diffusion model analysis,triangular wave tACS significantly increased the efficiency of non-target information processing.In addition,compared with sham conditions,triangular wave tACS reduced alpha power oscillations in the occipital lobe throughout the encoding period,while sinusoidal wave tACS increased theta power in the central frontal region only during the later encoding period.The brain network connectivity results showed that triangular wave tACS improved the clustering coefficient,local efficiency,and node degree intensity in the early encoding stage,and these parameters were positively correlated with the non-target drift rate and decision starting point.Our findings on how tACS modulates working memory indicate that triangular wave tACS significantly enhances brain network connectivity during the early encoding stage,demonstrating an improvement in the efficiency of working memory processing.In contrast,sinusoidal wave tACS increased the theta power during the later encoding stage,suggesting its potential critical role in late-stage information processing.These findings provide valuable insights into the potential mechanisms by which tACS modulates working memory.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3003601)Joint Funds of the National Natural Science Foundation of China Project on Earthquake Science(Grant No.U2239252)the program of the Innovative Research Team in China Earthquake Administration.
文摘Surface irregularities,such as hills and ridges,can significantly amplify ground motion caused by earthquakes.Therefore,in this study,we propose an analytical solution model to investigate the interaction between an asymmetric triangular hill on Earth and SH waves.Firstly,based on the development of wave functions and regional matching techniques,we introduce a semi-circular artificial auxiliary boundary,dividing the solution model into a semi-infinite body containing a semi-circular depression and an asymmetric fan-shaped region.Secondly,we derive the domain function form applicable to solving asymmetric problems.Utilizing the theory of complex variables,we establish a well-posed matrix for solving domain functions within the same coordinate system.Numerical results demonstrate that the scattering of SH waves by a protuberance is jointly influenced by the geometric parameters of the hill and the angle of incidence.Additionally,the frequency of the incident wave also has a certain degree of impact on the displacement amplitude.This study elucidates the scattering mechanism of SH waves by complex boundaries,providing a theoretical reference for building site selection and seismic design.In practical problems,the asymmetric assumption is more applicable than the symmetry assumption.
基金supported by the China Scholarship Council(CSC)(No.202206290131)。
文摘This paper presents an analysis of an equilateral triangular array formation initialization for space-based gravitational wave observatory(GWO)near Lagrange points in the circular-restricted three-body problem.A stable configuration is essential for the continuous observation of gravitational waves(GWs).However,the motion near the collinear libration points is highly unstable.This problem is examined by output regulation theory.Using the tracking aspect,the equilateral triangular array formation is established in two periods and the fuel consumption is calculated.Furthermore,the natural evolution of the formation without control input is analyzed,and the effective stability duration is quantified to determine the timing of control interventions.Finally,to observe the GWs in same direction with different frequency bands,scale reconfiguration is employed.
基金the National Natural Science Foundation of China(Grant Nos.50974081,50774051, 51034003)the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(Grant No.200958)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT0843)the Open Research Fund Program of the State Key Laboratory of Coal Resources and Safe Mining(China University of Mining and Technology, Beijing)(No.2007-07)
文摘To address the problem of subdividing inflexible rectangular grid models and their poor definition of velocity interfaces,we propose a complex structure triangular net for a minimum traveltime ray tracing global algorithm.Our procedure is：（1） Subdivide a triangle grid based on the Delaunay triangular subdivision criterion and the relationships of the points,lines,and the surfaces in the subdividing area.（2） Define the topology relationships and related concepts of triangular unit ray tracing.（3） The source point and wave arrival points at any time compose the propagating plane wave and the minimum traveltime and secondary source positions are calculated during the plane wave propagation.We adopt the hyperbolic approximation global algorithm for secondary source retrieving.（4） By minimum traveltime ray tracing,collect the path from receiver to source points with the neighborhood point＇s traveltime and the direction of the secondary source.Numerical simulation examples are given to test the algorithm.The results show that the triangular net ray tracing method demonstrates model subdivision flexibility,precise velocity discontinuity interfaces,and accurate computations.
文摘In this paper, antiplane response of an isosceles triangular hill to incident SH waves is studied based on the method of complex function and by using moving coordinate system. The standing wave function, which can satisfy the governing equation and boundary condition, is provided. Furthermore, numerical examples are presented; the influences of wave number and angle of the incident waves and the angle of the hill’s peak on ground motion are discussed.
文摘The influence of local landforms on ground motion is an important problem. The antiplane response of a scalene triangular hill to incident SH waves is studied in this paper by using a complex function, moving coordinates and auxiliary functions. First, the model is divided into two domains： a scalene triangular hill with a semi-circular bottom; and a half space with a semi-circular canyon. Wave functions that satisfy the zero-stress condition at the triangular wedges and at the horizontal surface are constructed in both domains. Then, considering the displacement continuity and stress equilibrium, algebraic equations are established. Finally, numerical examples are provided to illustrate the influence of the geometry of the hill and the characteristics of the incident waves on the ground motions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1530261 and 11572054)the Science Challenge Project,China(Grant No.TZ2016001).
文摘Damage depth is an important dynamic parameter for describing the degree of material damage and is also a key fundamental issue in the field of impact compression technology.The present work is dedicated to the damage depth of shock-melted metal in microspall under triangular wave loading,and an improved model of damage depth considering the material's compressibility and relative movement is proposed.The damage depth obtained from the proposed model is in good agreement with the laser-driven shock loading experiment.Compared with the previous model,the proposed model can predict the damage depth of shock-melted metal in microspall more accurately.Furthermore,two-groups of the smoothed particle hydrodynamics(SPH)simulations are carried out to investigate the effects of peak stress and decay length of the incident triangular wave on the damage depth,respectively.As the decay length increases,the damage depth increases linearly.As the peak stress increases,the damage depth increases nonlinearly,and the increase in damage depth gradually slows down.The results of the SPH simulations adequately reproduce the results of the proposed model in terms of the damage depth.Finally,it is found that the threshold stress criterion can reflect the macroscopic characteristics of microspall of melted metal.
文摘Scattering of SH-waves on the triangular hill joined by semi-cylindrical canyon in half-space is studied using the method of complex function and moving coordinates. The model being studied is divided into two domains. The wave functions satisfying the required condition at each wedge are constructed in each equation. The equations are solved with Fourier expansion. Numerical results are provided to discuss the influence of scattering of SH-waves.
基金supported by the National Natural Science Foundation of China(No.10632020).
文摘Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach. In this paper, the propagation of elastic waves in a two-dirnensional hybrid triangular lattice structure consisting of stainless steel cylinders in air is investigated theoretically. The band structure is calculated with the plane wave expansion （PWE） method. The hybrid triangular Bravais lattice is formed by two kinds of triangular lattices. Different from ordinary triangular lattices, the band gap opens at low frequency （between the first and the second bands） regime because of lifting the bands degeneracy at high symmetry points of the Brillouin zone. The location and width of the band gaps can be tuned by the position of the additional rods.
基金supported by the National Natural Science Foundation of China (11572332 and 11602274)the National Key R&D Program of China (2017YFC1404202)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB22040203)
文摘Internal solitary waves have been found to disintegrate into a series of solitons over variablebathymetry, with important applications for offshore engineering. Considering realisticbackground stratification in the South China Sea, internal solitary waves propagating over a stepare studied here. By assuming disintegrated solitons propagate independently, a theoreticalmodel, namely a triangular temporal-distribution law based on the Korteweg–de Vries theory, isproposed to describe the fission process of internal solitary waves undergoing disintegration. Aparameter is then introduced to quantify the accuracy of the theoretical model. The resultsindicate that the triangular law predicts the fission process better for a longer travelling distanceand a larger amplitude of internal solitary waves.
基金The project supported by National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province of China
文摘In this paper, based on new auxiliary nonlinear ordinary differential equation with a sixtb-aegree nonnneal term, we study the （2＋l ）-dimensional Davey-Stewartson equation and new types of travelling wave solutions are obtained, which include new bell and kink profile solitary wave solutions, triangular periodic wave solutions, and singular solutions. The method used here can be also extended to many other nonlinear partial differential equations.
