The time-dependent Ginzburg-Landau equation for the two-velocity difference model

A thermodynamic theory is formulated to describe the phase transition and critical phenomenon in traffic flow.Based on the two-velocity difference model,the time-dependent Ginzburg-Landau (TDGL) equation under certain condition is derived to describe the traffic flow near the critical point through the nonlinear analytical method.The corresponding two solutions,the uniform and the kink solutions,are given.The coexisting curve,spinodal line and critical point are obtained by the first and second derivatives of the thermodynamic potential.The modified Korteweg de Vries (mKdV) equation around the critical point is derived by using the reductive perturbation method and its kink-antikink solution is also obtained.The relation between the TDGL equation and the mKdV equation is shown.The simulation result is consistent with the nonlinear analytical result.     

固体线胀系数测定仪的改进

介绍一种新的固体线胀系数测量及温度控制方法．当温度测量精度为0．1℃时,在多个工作点上能在1．5min内保持恒温,从而消除了以往电加热方法中,由于忽略被测样品的热平衡时间而引起的误差．还自制了时间响应快的AD590M数字温度计,提高了测量精度．