Acta Physica Sinica 

About: Acta Physica Sinica is an academic journal published by Science Press. The journal publishes majorly in the area(s): Laser & Chaotic. It has an ISSN identifier of 1000-3290. It is also open access. Over the lifetime, 16210 publications have been published receiving 60065 citations. The journal is also known as: Wuli Xuebao & 物理学报.

Bound state in superconductors with paramagnetic impurities

Abstract: A generalized canonical transformation and a SCF method have been used to investigate the influence of isolated impurity atoms on the properties of superconductors. It has been found that a bound state of excitation exists around a paramagnetic impurity with its energy level in the energy gap. An analytical expression has been obtained for the corresponding wave function. The effect of electromagnetic absorption due to the bound state should appear as a precursory peak. The possible experimental verifications of the bound state through tunnelling effect and infrared absorption are discussed.Futhermore, the excitations of continuous spectra around a nonmagnetic impurity and the spatial variation of the energy gap parameter have been considered.

On some variational principles in the theory of elasticity and the theory of plasticity

Abstract: In this paper, some general variational principles in the theory of elasticity and the theory of plasticity are established. Consider an elastic body in equilibrium with small displacement. By regarding u, v, w, e x , e y , e z , y yz , y xz , y xy , σ x,σ y, σ z,τ yz ,τ xz ,τ xy as fifteen independent functions, and letting their variations be free from any restriction, we establish two variational principles, called the principle of generalized complementary energy and the principle of generalized potential energy. Each principle is equivalent to the four sets o?fundamental equations of the theory of elasticity, namely, the equations of equilibrium, the stress strain relations, the strain displacement relations and the appropriate boundary conditions. Special cases of these principles are examined. These principles are next expressed in other forms, where u, v, w, σ x ,σ y , σ z ,τ yz ,τ xz ,τ xy are regarded as nine independent functions with their variations free from any restrictions. Next we consider the bending of a thin elastic plate with supported edges under large deflection. By regarding M x , M y , M xy , N x , N y , N xy , u, v, w as nine independent functions with the restriction that w should vanish along the contour of the plate, we establish a variational principle, called the principle of generalized potential energy, which is equivalent to the three sets of fundamental equations in the theory of bending of thin plate, namely, the equations of equilibrium, the displacement stress relations (strain stress relations) and the appropriate boundary conditions. This principle is next expressed in another form which is more convenient for application. As an illustration, von Karman's equations for the large deflection of thin plate are derived from this principle. In von Karman's equations, one unknown is the deflection and the other unknown is the membrane stress function. Therefore it is impossible to derive von Karman's equations either from the principle of minimum potential energy or from the principle of complementary energy. Finally we consider the equilibrium of a plastic body with small displacement. In the case of the deformation type of stress strain relations, we establish two variational principles, each of which is equivalent to the equations of equilibrium, a certain type of stress strain relations and the appropriate boundary conditions. In these variational principles, u, v, w and their variations are free from any restriction, and σ x ,σ y , σ z ,τ yz ,τ xz ,τ xy and their variations satisfy a certain yield condition. In the case of the flow type of stress strain relations, we get two similar variational principles, in which u, v, w and their variations are free from any restriction, σ x ,σ y , σ z , τ yz ,τ xz ,τ xy and their variations satisfy a certain yield condition and σ x ,σ y , σ z , τ yz ,τ xz ,τ xy have no variations.

Trial equation method and its applications to nonlinear evolution equations

Abstract: A new method, that is, trial equation method, was given to obtain the exact trav eling wave solutions for nonlinear evolution equations. As an example, a class o f fifth-order nonlinear evolution equations was discussed. Its exact traveling w ave solutions, which included rational form solutions, solitary wave solutions, triangle function periodic solutions, polynomial type Jacobian elliptic function periodic solutions and fractional type Jacobian elliptic function periodic solu tions, were given.

Multiple velocity difference model and its stability analysis

Abstract: Based on the full velocity difference (FVD) model proposed by Jiang and Wu, we present an extended car_following model, called the multiple velocity difference (MVD) model. We attempt to enhance the stability of the traffic flow by using the velocity differences of multiple vehicles. It can be found that the critical value of the sensitivity in the MVD model decreases and the stable region is apparently enlarged, compared with the FVD model. Additionally, the simulated results suggest that the MVD model can suppress the traffic jam effectively.

Large deflection of a circular clamped plate under uniform pressure

Abstract: The problem of large deflection of a clamped circular plate under uniform pressure is studied by the method of successive approximation in terms of the parameter representing the ratio of the center deflection to the thickness. The tedious numerical computations, involved in Way's power series solution are thus avoided. The yielding condition at the edge checks very well with the experimental results given by McPherson, Ramberg and Levy. The method may be easily extended to any other boundary conditions and loading details.