Algebraic approach and coherent states for a relativistic quantum particle in cosmic string spacetime

We study a relativistic quantum particle in cosmic string spacetime in the presence of a magnetic field and a Coulomb-type scalar potential. It is shown that the radial part of this problem possesses the su(1,1)$su(1,1)$ symmetry. We obtain the energy spectrum and eigenfunctions of this problem by using two algebraic methods: the Schrödinger factorization and the tilting transformation. Finally, we give the explicit form of the relativistic coherent states for this problem.     

Proposed sets of critical exponents for randomly branched polymers,using a known string theory model

The critical exponent ν for randomly branched polymers with dimensionality d equal to 3, is known exactly as 1/2. Here, we invoke an already available string theory model to predict the remaining static critical exponents. Utilizing results of Hsu et al. (Comput Phys Commun. 2005;169:114–116), results are added for d = 8. Experiment plus simulation would now be important to confirm, or if necessary to refine, the proposed values.     

Dispersion and attenuation by transmission,reflection, and mode conversion in welded pipes

Torsional wave dispersion and attenuation in an open empty welded pipe are determined from a multi-receiver position reflection experiment. The fundamental torsional wave is dominantly reflected at the free end and the converted non-axisymmetric flexural modes are naturally attenuated. The resulting phase velocity contours are in agreement with theoretical predictions. The transmission losses are quantified and compared to those reflective elements associated with end and weld reflection. At any reflective node, the incident wave is split between back and forward preserved mode scattering (“reflection/transmission”), conversion to other modes plus energy lost by absorption. The ratios for each element are quantified.     

Abnormality in using cyclic fatigue for ranking static fatigue induced slow crack growth behavior of polyethylene pipe grade resins

Slow crack growth behavior in polyethylene pipe grade resins were studied using both static fatigue (stress-rupture) and cyclic fatigue tests. This was done to better understand the applicability of cyclic fatigue in the prediction of slow crack growth ranking determined from the static fatigue test. In all polyethylene pipe grade resins tested at 80 °C, reduced crack growth failure times were exhibited when the cyclic fatigue test was employed. However, when applied to rank the resins through their slow crack failure times, the cyclic fatigue results did not always confirm those obtained from the static fatigue test. That is, in some cases, a resin with higher slow crack resistance ranking (longer failure times) than another resin in static fatigue exhibited lower ranking (shorter failure times) in the cyclic fatigue test. This abnormality of reversal in ranking is not a general observation but does occur. Based on the data obtained so far, when resins with smaller differences between static fatigue and cyclic fatigue slow crack growth failure times are compared with those resins having larger differences, the chances of correctly predicting the ranking obtained from static fatigue using cyclic fatigue tend to decrease. Hence, it is suggested that one needs to practice caution when using cyclic fatigue to predict the static fatigue ranking of resins for slow cracking resistance. Some insight into the cause of such abnormality is discussed with reference to creep-fatigue interactions.     

The real solution to scalar field equation in 5D black string space

After the nontrivial quantum parameters Ω _n and quantum potentials V _n obtained in our previous research, the circumstance of a real scalar wave in the bulk is studied with the similar method of Brevik and Simonsen (Gen. Rel. Grav. 33:1839, 2001). The equation of a massless scalar field is solved numerically under the boundary conditions near the inner horizon r _e and the outer horizon r _c . Unlike the usual wave function Ψ_ωl in 4D, quantum number n introduces a new functions Ψ_{ωl n} , whose potentials are higher and wider with bigger n. Using the tangent approximation, a full boundary value problem about the Schrödinger-like equation is solved. With a convenient replacement of the 5D continuous potential by square barrier, the reflection and transmission coefficients are obtained. If extra dimension does exist and is visible at the neighborhood of black holes, the unique wave function Ψ_{ωl n} may say something to it.     

Multiparticle correlations in resonance-matter formation

The effect of multiparticle correlations on resonance and pion populations, in relativistic nuclear reactions, is calculated in the context of an intranuclear cascade model which includes N-body (N > 2) collisional processes. The resonance-matter population present in the highly-compressed phase of nucleus-nucleus collisions is investigated, in reactions between different intermediate-mass nuclear systems. Received: 29 December 1998 / Revised version: 20 December 1999     

非牛顿流体在环管内的不定常旋转流

本文研究幂律非牛顿流体在环管内的不定常旋转流。该方程是一非线性方程,在部分因子的稳态近似假设之下,方程被线性化,用Laplace积分变换法我们获得了问题的解。文中给出了几组解曲线,它反映了角向速度的时间演化规律与空间分布特征。另外我们专门研究了幂律指数对流场的影响,该参数的敏感性具有一定的数值界限。这一结果,在有关的工程设计中具有重要的意义。     

HARMONIC SOLUTIONS OF SOME SECOND-ORDER NONLINEAR EQUATIONS UNDER A PERIODIC FORCE

In this paper we prove some theorems on the existence of harmonic solutions of somesecond-order nonlinear equations under a periodic force.These theorems extend relevantresults in refs.[1]-[8].     

测量透明管壁厚的理论研究

透明管（如玻璃管）壁厚几何尺寸的公差大小是玻管生产中产品质量优劣的重要指标之一;因此透明管的壁厚测量的精度尤为重要。根据光矢量场的电磁场理论仔细分析了透明管在平面光波中的透射和反射的光学特性;并研究其能量分布。用ＣＣＤ作接收器件,进行非接触测量实验系统实验,将理论值与实验值相比较,提出了精确测量透明管壁厚的可行性方法     

固—液耦合Timoshenko管道的稳定性分析

根据Ｈａｍｉｌｔｏｎ原理的固－液耦合振同分方程用幂级数法计算了Ｔｉｍｏｓｈｅｎｋｏ管道的固有频率和临界流速。给出了管道前三阶固有频率－流速的关系曲线,分析了转动惯量对该输流管道的稳定特性的影响。计算结果表明,转动一对两端简支的固－液合Ｔｉｍｏｓｈｅｎｋｏ管道的静力失稳没有影响,但对其频率特性和动力失稳有影响。