Lie symmetries and conserved quantities of controllable nonholonomic dynamical systems

This paper concentrates on studying the Lie symmetries and conserved quantities of controllable nonholonomic dynamical systems. Based on the infinitesimal transformation, we establish the Lie symmetric determining equations and restrictive equations and give three definitions of Lie symmetries before the structure equations and conserved quantities of the Lie symmetries are obtained. Then we make a study of the inverse problems. Finally, an example is presented for illustrating the results.     

间隔不变性与相对论拉格朗日力学

文章证明由时空和速度间隔不变性可以导出相对论哈密顿和拉格朗日力学，由此说明哈密顿或拉格朗日为洛仑兹不变量是时空和速度间隔不变性的必然结果。     

工科物理如何讲力学量算符

通过分析对波函数的作用引入动量算符，以哈密顿量为例证明或验证力学量算符的性质，用本征值和状态展开系数的模方表示力学量的平均值，说明力学量用算符表达是微观体系测量的不确定性和统计特征的要求。     

Luminescent Properties and Mechanism of Gd1-x-yAlO3Eux,REy

GAP:Eu,Re(Gd1-x-yAlO3Eux,REy?A，RE=Pr or Ce) powders were prepared by a nitrate-citrate process. It is found that luminescent intensity decreases when GAP:Eu is co-doped with Pr or Ce. The phenomena of spectra prove that there is a resonant energy transfer between Eu and Pr, by the absorption and emission of lower-energy phonon, and also Ce sensitizer decreases the activator energy level from host→Eu. The two factors are considered to be the main reasons for decrease of the luminescent intensity for the co-doped GAP:Eu,Re.     

Nonlinear Correlations of Protein Sequences and Symmetries of Their Structures

We investigate the nonlinear correlations of protein sequences by using the nonlinear prediction method developed in nonlinear dynamical theory. It is found that a lot of protein sequences show strong nonlinear correlations and have deterministic structures. Further investigations show that the strong nonlinear correlations of these protein sequences are due to the symmetries of their tertiary structures. Furthermore, the correlation lengths of the sequences are related to the degrees of the symmetries. These results support the duplication mechanism of protein evolution and also reveal one aspect how amino acid sequences encode their spatial structures.     

二甲酸二脂系玻璃化转变的力学谱研究

本文用最近发明的液态低频力学谱方法对二甲酸二脂系列样品进行了测量,验证了该方法的可信性与有效性,并且表明它能够提供物质变化的丰富信息.研究结果还表明,随着分子内部自由度的增加、二甲酸二脂系列的玻璃化转变温度表现出先减小然后又增加、但脆性是先增加后减小的有趣又难以理解反常趋势.     

多孔NiTi形状记忆合金阻尼性能的测量和应用

本文利用苏州职业大学测试技术研究所设计改进的LMR-1型低频力学驰豫谱测量系统(低频扭摆式内耗仪)强迫振动方式,在0℃～200℃温度范围内测量了不同成分和孔隙率NiTi合金的内耗和模量性质,为设计多孔NiTi合金在耗能减振方面的应用提供依据.     

Design of phase plates for shaping partially coherent beams by simulated annealing

Taking the Gaussian Schell-model beam as a typical example of partially coherent beams, this paper applies the simulated annealing （SA） algorithm to the design of phase plates for shaping partially coherent beams. A flow diagram is presented to illustrate the procedure of phase optimization by the SA algorithm. Numerical examples demonstrate the advantages of the SA algorithm in shaping partially coherent beams. An uniform flat-topped beam profile with maximum reconstruction error RE 〈 1.74% is achieved. A further extension of the approach is discussed.     

光谱开关与多色光场的奇点光学效应

推导出多色高斯光束和高斯-谢尔模型光束通过杨氏实验双缝传输的谱强度公式.对完全空间相干光和部分空间相干光照明杨氏实验装置出现的光谱开关作了详细研究,并判断其是否属于奇点光学效应. 结果表明：多色场奇点光学效应的判据应当是光谱开关出现时的谱强度极小值S_min=0,而不是总光强极小值I_min=0. 当用多色高斯-谢尔模型光束照明杨氏实验装置时,在近场和远场产生的光谱开关都不属于奇点光学效应. 当用多色高斯光束照明杨氏实验装置时,只有远场产 关键词： 光谱开关 奇点光学效应 完全相干和部分相干 多色光场     

Si中30度部分位错弯结运动特性的分子模拟

首先使用分子动力学方法(MD)得出了左弯结(LK)和右弯结(RK)在不同温度和剪应力作用下的速度特性和运动过程.然后利用基于紧束缚势(TB)的nudged elastic band(NEB)方法计算LK和RK的迁移势垒.由计算结果得出,单个LK或RK的势垒很高,运动速度相对较慢;LK中的多弯结对结构和由RK分解产生的右弯结-重构缺陷(RC)能够加速位错运动;其中,RC能促进30°部分位错更快地迁移.