对象散全息元件产生的正交象散特性的研究

本文从理论上分析了用全息方法制作具有象散特征的一种光学元件——象散全息元件——的可能性,并得到实验上的证明.对由象散全息元件在空间正交方向上产生的象散特性作了较为仔细的研究,给出了实验结果.若用此元件代替普通象散系统,将具有使用方便,经济等优点.     

大学物理实验教学改革探索——谈“少台套大循环”教学模式与管理

教学改革的最终目标都是为了有益于学生的全面发展以及实践能力的提高。以大学物理实验改革为例,介绍了＂少台套大循环＂的实验改革与教学管理方法。经过两年多＂少台套大循环＂的运行,这种改革不仅提高了学生的实验操作能力,而且在教学资源有效配置方面探索出一种可行的运行模式。     

A type of conserved quantity of Mei symmetry of Nielsen equations for a holonomic system

A type of structural equation and conserved quantity which are directly induced by Mei symmetry of Nielsen equations for a holonomic system are studied.Under the infinitesimal transformation of the groups,from the definition and the criterion of Mei symmetry,a type of structural equation and conserved quantity for the system by proposition 2 are obtained,and the inferences in two special cases are given.Finally,an example is given to illustrate the application of the results.     

Preparation of Nd-doped BiFeO3 films and their electrical properties

The Nd-doped BiFeO₃ thin films were prepared on SnO₂(FTO) substrates spin-coated by the sol–gel method using Nd(NO₃)₃·6H₂O, Fe(NO₃)₃·9H₂O and Bi(NO₃)₃·5H₂O as raw materials. The microstructure and electric properties of the BiFeO₃ thin films were characterized and tested. The results indicate that the diffraction peak of the Nd-doped BiFeO₃ films is shifted towards right as the doping amounts are increased. The structure is transformed from the rhombohedral to pseudotetragonal phase. The crystal grain is changed from an elliptical to irregular polyhedron. Structure transition occurring in the Bi_0.85Nd_0.15FeO₃ films gives rise to the largest Pr of 64 μC/cm². The leakage conductance of the Nd doped thin films is reduced. The dielectric constant and dielectric loss of Bi_0.85Nd_0.15FeO₃ thin film at 10 kHz are 190 and 0.017 respectively.     

相对论性力学系统的Birkhoff对称性与守恒量

提出了相对论性力学系统的一种新的对称性,并给出了此对称性导致的守恒量.提出了相对论性力学系统的Birkhoff对称性,即对应于相对论性力学系统的一组Birkhoff动力学函数的运动微分方程的解都满足从另一组Birkhoff动力学函数得到的运动微分方程.证明了与两组Birkhoff动力学函数分别给出的相对论性Birkhoff方程相关联的系数矩阵的各次幂的迹是系统的一个守恒量,从而将Currie和Saletan提出的力学系统的等效Lagrange函数定理拓展到了相对论性Birkhoff动力学系统.给出了两个例子以说明结果的正确性.     

热采耦合数学模型定量化研究及数值模拟

针对稠油油藏开发过程的薄弱环节,提出了油藏热质传递过程的黑箱分析法和白箱分析法,建立了包含蒸汽相的稠油热采耦合黑箱模型和白箱模型,使得储层温度场模型得以完整化和系统化。应用CMG软件进行数值模拟,验证了所建数学模型的合理性,并得到了孔隙度对油藏温度的影响关系。最后,对油藏热流体的指进现象进行了机理分析,并总结了热流体指进现象的产生范围。     

Conformal invariance and conserved quantities of Birkhoff systems under second-class Mei symmetry

This paper proposes a new concept of the conformal invariance and the conserved quantities for Birkhoff systems under second-class Mei symmetry.The definition about conformal invariance of Birkhoff systems under second-class Mei symmetry is given.The conformal factor in the determining equations is found.The relationship between Birkhoff system’s conformal invariance and second-class Mei symmetry are discussed.The necessary and sufficient conditions of conformal invariance,which are simultaneously of second-class symmetry,are given.And Birkhoff system’s conformal invariance may lead to corresponding Mei conserved quantities,which is deduced directly from the second-class Mei symmetry when the conformal invariance satisfies some conditions.Lastly,an example is provided to illustrate the application of the result.     

非完整系统Tzénoff方程的Mei对称性和守恒量

研究了在群的无限小变换下非完整系统Tzénoff方程的Mei对称性，给出了非完整系统Tzénoff方程Mei对称性的定义和判据方程.给出了这种Mei对称性导致Lie对称性的充要条件，通过特殊Mei对称性条件下的Lie对称性，找到了非完整系统Tzénoff方程的Hojman守恒量.     

The Lagrangian and the Lie symmetries of charged particle motion in homogeneous electromagnetic field

In this paper, a constant of motion of charged particle motion in homogeneous electromagnetic field is derived from Newton's equations and the characteristics of partial differential equation, the related Lagrangian is also given by means of the obtained constant of motion. By discussing the Lie symmetry for this classical system, this paper obtains the general expression of the conserved quantity. It is shown that the conserved quantity is the same as the constant of motion in essence.     

A New Type of Conserved Quantity of Mei Symmetry for Relativistic Variable Mass Mechanical System in Phase Space

In this paper, a new type of conserved quantity directly deduced from the Mei symmetry for relativistic variable mass system in phase space is studied. The definition and the criterion of the Mei symmetry for the system are given. The conditions for existence and the form of the new conserved quantity are obtained. Finally, an example is given to illustrate the application of the results.