Fast Lagrangian analysis of continua(FLAC) was used to study the influence of pore pressure on the mechanical behavior of rock specimen in plane strain direct shear, the distribution of yielded elements, the distribut...Fast Lagrangian analysis of continua(FLAC) was used to study the influence of pore pressure on the mechanical behavior of rock specimen in plane strain direct shear, the distribution of yielded elements, the distribution of displacement and velocity across shear band as well as the snap-back (elastic rebound) instability. The effective stress law was used to represent the weakening of rock containing pore fluid under pressure. Numerical results show that rock specimen becomes soft (lower strength and hardening modulus) as pore pressure increases, leading to higher displacement skip across shear band. Higher pore pressure results in larger area of plastic zone, higher concentration of shear strain, more apparent precursor to snap-back (unstable failure) and slower snap-back. For higher pore pressure, the formation of shear band-elastic body system and the snap-back are earlier; the distance of snap-back decreases; the capacity of snap-back decreases, leading to lower elastic strain energy liberated beyond the instability and lower earthquake or rockburst magnitude. In the process of snap-back, the velocity skip across shear band is lower for rock specimen at higher pore pressure, showing the slower velocity of snap-back.展开更多
In this paper, we investigate the complex dynamics of two-species Ricker-type discrete-time competitive model. We perform a local stability analysis for the fixed points and we will discuss about its persistence for b...In this paper, we investigate the complex dynamics of two-species Ricker-type discrete-time competitive model. We perform a local stability analysis for the fixed points and we will discuss about its persistence for boundary fixed points. This system inherits the dynamics of one-dimensional Ricker model such as cascade of period-doubling bifurcation, periodic windows and chaos. We explore the existence of chaos for the equilibrium points for a specific case of this system using Marotto theorem and proving the existence of snap-back repeller. We use several dynamical systems tools to demonstrate the qualitative behaviors of the system.展开更多
The RC-IGBT（reverse conducting insulated gate bipolar transistor） is a new kind of power semiconductor device which has many advantages such as smaller chip size,higher power density,lower manufacturing cost,softer ...The RC-IGBT（reverse conducting insulated gate bipolar transistor） is a new kind of power semiconductor device which has many advantages such as smaller chip size,higher power density,lower manufacturing cost,softer turn off behavior,and better reliability.However,its performance has a number of drawbacks,such as the snap-back effect.In this paper,an introduction about the snap-back effect of the RC-IGBT is given firstly. Then the physical explanations are presented with two simplified models.After that,some numerical simulations are carried out to verify the correctness of the models.展开更多
Based on the continuity of the derivatives of the Non-Uniform Rational B-Splines (NURBS) curve and the Jaumann strain measure, the present paper adopted the position coordinates of the control points as the degrees of...Based on the continuity of the derivatives of the Non-Uniform Rational B-Splines (NURBS) curve and the Jaumann strain measure, the present paper adopted the position coordinates of the control points as the degrees of freedom and developed a planar rotation-free Euler-Bernoulli beam element for isogeometric analysis, where the derivatives of the field variables with respect to the arc-length were expressed as the sum of the weighted sum of the position coordinates of the control points, and the NURBS basis functions were used as the weight functions. Furthermore, the concept of bending strip was used to involve the rigid connection between multiple patches. Several typical examples with geometric nonlinearities were used to demonstrate the accuracy and effectiveness of the proposed algorithm. The presented formulation fully accounts for the geometric nonlinearities and can be used to study the snap-through and snap-back phenomena of flexible beams.展开更多
The chaotic behavior of one-dimensional, 2-segment and 3-segmentpiecewise-linear maps is examined by using the concept of snap-back repellers introduced by Marottoand the parameters conditions of existence for snap-ba...The chaotic behavior of one-dimensional, 2-segment and 3-segmentpiecewise-linear maps is examined by using the concept of snap-back repellers introduced by Marottoand the parameters conditions of existence for snap-back repeller are obtained. Simulation resultsare presented to show the snap-back repeller, some periodic points and attracting interval cycleswith chaotic intervals.展开更多
基金Project(50309004) supported by the National Natural Science Foundation of China
文摘Fast Lagrangian analysis of continua(FLAC) was used to study the influence of pore pressure on the mechanical behavior of rock specimen in plane strain direct shear, the distribution of yielded elements, the distribution of displacement and velocity across shear band as well as the snap-back (elastic rebound) instability. The effective stress law was used to represent the weakening of rock containing pore fluid under pressure. Numerical results show that rock specimen becomes soft (lower strength and hardening modulus) as pore pressure increases, leading to higher displacement skip across shear band. Higher pore pressure results in larger area of plastic zone, higher concentration of shear strain, more apparent precursor to snap-back (unstable failure) and slower snap-back. For higher pore pressure, the formation of shear band-elastic body system and the snap-back are earlier; the distance of snap-back decreases; the capacity of snap-back decreases, leading to lower elastic strain energy liberated beyond the instability and lower earthquake or rockburst magnitude. In the process of snap-back, the velocity skip across shear band is lower for rock specimen at higher pore pressure, showing the slower velocity of snap-back.
文摘In this paper, we investigate the complex dynamics of two-species Ricker-type discrete-time competitive model. We perform a local stability analysis for the fixed points and we will discuss about its persistence for boundary fixed points. This system inherits the dynamics of one-dimensional Ricker model such as cascade of period-doubling bifurcation, periodic windows and chaos. We explore the existence of chaos for the equilibrium points for a specific case of this system using Marotto theorem and proving the existence of snap-back repeller. We use several dynamical systems tools to demonstrate the qualitative behaviors of the system.
基金Project supported by the National Major Science and Technology Special Project of China(No.2011ZX02504-002)
文摘The RC-IGBT（reverse conducting insulated gate bipolar transistor） is a new kind of power semiconductor device which has many advantages such as smaller chip size,higher power density,lower manufacturing cost,softer turn off behavior,and better reliability.However,its performance has a number of drawbacks,such as the snap-back effect.In this paper,an introduction about the snap-back effect of the RC-IGBT is given firstly. Then the physical explanations are presented with two simplified models.After that,some numerical simulations are carried out to verify the correctness of the models.
基金Project supported by the National Natural Science Foundation of China(Nos.11572132 and 11572137)
文摘Based on the continuity of the derivatives of the Non-Uniform Rational B-Splines (NURBS) curve and the Jaumann strain measure, the present paper adopted the position coordinates of the control points as the degrees of freedom and developed a planar rotation-free Euler-Bernoulli beam element for isogeometric analysis, where the derivatives of the field variables with respect to the arc-length were expressed as the sum of the weighted sum of the position coordinates of the control points, and the NURBS basis functions were used as the weight functions. Furthermore, the concept of bending strip was used to involve the rigid connection between multiple patches. Several typical examples with geometric nonlinearities were used to demonstrate the accuracy and effectiveness of the proposed algorithm. The presented formulation fully accounts for the geometric nonlinearities and can be used to study the snap-through and snap-back phenomena of flexible beams.
基金Supported by the National Natural Science Foundation of China "Tian Yuan" (A0324626)
文摘The chaotic behavior of one-dimensional, 2-segment and 3-segmentpiecewise-linear maps is examined by using the concept of snap-back repellers introduced by Marottoand the parameters conditions of existence for snap-back repeller are obtained. Simulation resultsare presented to show the snap-back repeller, some periodic points and attracting interval cycleswith chaotic intervals.
