Deformation due to time harmonic sources in micropolar thermoelastic medium possessing cubic symmetry with two relaxation times

The response of a micropolar thermoelastic medium possessing cubic symmetry with two relaxation times due to time harmonic sources is investigated. Fourier transform is employed and the transform is inverted by using a numerical inversion technique. The components of displacement, stress, microrotation and temperature distribution in the physical domain are obtained numerically. The results of normal displacement, normal force stress, tangential couple stress and temperature distribution are compared for micropolar cubic crystal and micropolar isotropic solid. The numerical results are illustrated graphically for a particular material. Some special cases are also deduced.     

Eigenfrequency analysis of cable structures with inclined cables

The approximate eigenfrequencies for the in-plane vibrations of a cable struc- ture consisting of inclined cables,together with point masses at various points were com- puted.It was discovered that the classical transfer matrix method was inadequate for this task,and hence the larger exterior matrices were used to determine the eigenfrequency equation.Then predictions of the dynamics of the general cable structure based on the asymptotic estimates of the exterior matrices were made.     

Analytical solutions of steady vibration of free rectangular plate on semi-infinite elastic foundation

The method of double Fourier transform was employed in the analysis of the semi-infinite elastic foundation with vertical load.And an integral representations for the displacements of the semi-infinite elastic foundation was presented.The analytical solution of steady vibration of an elastic rectangle plate with four free edges on the semi-infinite elastic foundation was also given by combining the analytical solution of the elastic rectangle plate with the integral representation for displacements of the semi- infinite elastic foundation.Some computational results and the analysis on the influence of parameters were presented.     

Laser-manipulated the multiphoton transitions of a harmonically trapped particle

A single particle magneto-confined in a one-dimensional (1D) quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a $\delta$ potential. The theoretical investigation has demonstrated that for a sufficiently strong $\delta$ pulse the quantum motional stationary state of the particle is one of the eigenstates of the free harmonic oscillator, and it is determined by the site of the laser beam uniquely, namely a quantum state is admissible if and only if the laser site is one of its nodes. The numerical computation shows that all the nodes of the lower energy states with quantum numbers $n \le 20$, except the coordinate origin, are mutually different. So we can manipulate the multiphoton transitions between the quantum states by adjusting the position of the laser $\delta$ pulse and realize the transition from an unknown higher excitation state to a required lower energy state.     

Supplement to the previous application of the first junction condition to a highly symmetric spacetime

Application of the first junction condition to a highly symmetric spacetime was investigated recently in {\it Chin. Phys. Lett.} B {\bf 546} 189 2006, where a partial differential equation arising from the connection of the Robertson--Walker and the Schwarzschild--de Sitter metrics was presented, but no solutions of the equation were provided. Here we provide a proof to the statement that there exist solutions of the equation. In addition, an example of the solution and some analyses associated with this issue are presented. We find that in connecting the two metrics, there are three conditions which should be satisfied. Of these conditions, one condition constrains the place where the two metrics can take the same value for a local system whose mass is provided which marks the boundary of the system, and the other two constrain the transformation form. In realizing the connection of the two metrics, the latter two conditions are required to be satisfied only at the boundary defined by the former condition.     

Noether symmetry and non-Noether conserved quantity of the relativistic holonomic nonconservative systems in general Lie transformations

For a relativistic holonomic nonconservative system, by using the Noether symmetry, a new non-Noether conserved quantity is given under general infinitesimal transformations of groups. On the basis of the theory of invariance of differential equations of motion under general infinitesimal transformations, we construct the relativistic Noether symmetry, Lie symmetry and the condition under which the Noether symmetry is a Lie symmetry under general infinitesimal transformations. By using the Noether symmetry, a new relativistic non-Noether conserved quantity is given which only depends on the variables $t$, $q_s $ and $\dot {q}_s $. An example is given to illustrate the application of the results.     

Low-Energy Kπ Phase Shifts in Chiral SU（3） Quark Model

The low-energy region kaon-pion S- and P-wave phase shifts with isospin I = 1/2 and I = 3/2 are dynamically studied in the chiral SU（3） quark model by solving a resonating group method equation. The model parameters are taken to be the values fitted by the energies of the baryon ground states and the kaon-nucleon elastic scattering phase shifts of different partial waves. As a preliminary study the s-channel qq^- annihilation interactions are not included since they only act in the very short range and are subsequently assumed to be unimportant in the low-energy domain. The numerical results are in qualitative agreement with the experimental data.     

快中子照相胶片成像法的初步实验

利用9Be(d,n)反应在北京大学4.5MV静电加速器上产生小于7MeV能区的快中子,采用胶片法进行了快中子照相的初步实验.对快中子胶片成像法的基本性能进行了初步的测试和研究.用国产的原材料研制了一种适用于快中子照相的关键部件－快中子转换屏.实验结果表明研制的快中子转换屏能够满足快中子照相的需要.A preliminary experiment is conducted with direct film method under the condition that fast neutron is generated by the reaction of 9Be (d,n) on the Peking University 4.5 MV Van de Graff, whose energy is lower than 7 MeV.Basic characteristics of direct-film neutron radiography system is researched with the help of samples in different materials, different thickness and holes of different diameter. The fast neutron converter, which is vital for fast neutron imaging, is produced with the materials made in china. The result indicates that fast neutron converter can meet the requirment of fast neutron imaging; what's more, further research of fast neutron imaging can be conducted on the accelerator and neutron-generator in China.     

掺铥硫氧化钇的特殊余辉性质

迄今为止,稀土长余辉磷光体已见文献或专利公开报道的激活离子主要有适于紫外光激发的三价铈离子(Ce³⁺)和三价镨离子(Pr³⁺)、适于可见光激发的铕离子(Eu³⁺和Eu²⁺)及钐离子(Sm³⁺,Sm²⁺),尚未涉及到铥离子Tm³⁺或Tm²⁺.我们在Tm³⁺离子激活的硫氧化钇体系Y₂O₂S:Tm³⁺中发现了长余辉荧光特性.特别是在该磷光体中还发现了一种非常特殊的余辉现象.     

未知动力学模型的化学反应过程的解析

采用迭代目标转换因子分析法(ITTFA)解析动力学模型未知的化学反应过程中的动力学-光谱数据矩阵,获得了各组分的动力学谱.基于体系中各组分间的等吸收点等光谱特征,提出并建立了一种新的初始迭代矢量的方法.利用该方法解析了动力学模型未知且各组分均有吸收的两步连续反应的模拟数据矩阵,并对最终产物无吸收的水杨酸水溶液电降解反应过程中测得的数据矩阵进行解析,获得了可靠的结果.