Axisymmetric Thermoelastic Interactions without Energy Dissipation in an Unbounded Body with Cylindrical Cavity

The linear theory of thermoelasticity without energy dissipation is employed to study thermoelastic interactions in a homogeneous and isotropic unbounded body containing a cylindrical cavity. The interactions are supposed to be due to a constant step in radial stress or temperature applied to the boundary of the acvity, which is maintained at a constant temperature or zero radial stress (as the case may be). By using the Laplace transform technique, it is found that the interactions consist of two coupled waves both of which propagate with a finite speed but with no attenuation. The discontinuities that occurs at the wavefronts are computed. Numerical results applicable to a copper-like material are presented.     

圆柱壳大开孔问题——单圆孔的理论解

从Ｄｏｎｎｅｌｌ圆柱壳方程出发，利用复变函数与保角映射的方法，将圆柱壳展开面上的开孔边界线保角晨射成单位圆，并在映射平面上给出了逼近大开孔圆柱壳方程解答的完备函数逼近序列，进而利用边界条件和正交函数展开的方法得到了自由孔边应力集中系数的表达式，最后，对具有开孔率的圆柱壳在不同荷载条件下的自由孔口边界上的应力集中的系数进行了计算，此种方法，同时研究圆柱壳开非圆大孔和接管等问题提供了可能性。     

有限长圆柱壳中轴对称弹性瞬态波

有限长的计及剪切变形和转动惯性的弹性圆柱壳的轴对称运动方程经过Laplace变换后转化为一组相空间中的方程。对该方程组作了一些适当的处理后,应用广义射线法,得到了相空间中位移和内力的射线法表达式。采用快速Fourier变换作Laplacl逆变换,即可得到圆柱壳受轴对称冲击载荷时的弹性瞬态波解。     

岩石爆破的粉碎区及其空腔膨胀

本文根据爆炸冲击波的理论分析,讨论了柱形装药和球形装药的粉碎区半径、炮孔近区的压缩比、爆破空腔及其空腔的发展时间。通过分析,给出柱形装药的爆炸近区参数。计算结果表明:2号铵梯岩石炸药柱形装药在岩石介质中产生的粉碎区半径一般是炮孔半径的1.65～3.05倍,球装药在岩石介质中产生的粉碎区半径是球形装药半径的1.28～1.75倍;柱形装药在孔壁处的冲击波波长与炮孔半径属于同一量级;粉碎区内的平均压缩比为1.05～1.10。     

用于抛物柱面空间功率合成天线的功分喇叭阵列

 提出了一种用于偏馈抛物柱面反射天线的功分喇叭。由于改善了口面上的电磁分布,该功分喇叭可以让馈源阵列的栅瓣电平抑制到－28 dB。用FEKO进行仿真发现,与传统用角锥喇叭阵列作为馈源的抛物柱面反射天线相比,使用功分喇叭直线阵列可以使空间功率合成天线的效率从68%提高到80%,同时天线的增益也能增加0.7 dB。     

带有反射腔的双频相对论返波管的粒子模拟

 设计了一种带有反射腔的能在X波段实现稳定双频输出的圆柱结构相对论返波管,采用2.5维相对论全电磁PIC粒子模拟软件行粒子模拟研究。仿真结果表明:在输入电压433 kV、引导磁场2.2 T的条件下,实现了9.53,10.09 GHz的双频稳定输出,平均输出功率340 MW,平均功率效率24.1%。     

Z箍缩驱动器与丝阵负载耦合特性研究

以丝阵内爆零维模型为基础,采用Pspice模拟行为建模方法,建立了丝阵内爆动态电感与Z箍缩驱动器耦合的全电路模型,实现驱动器放电过程与丝阵内爆过程的自洽求解,并研究了丝阵参数、电路参数对内爆过程的影响.结果表明:丝阵负载与驱动器存在强耦合关系,丝阵参数、电路参数对丝阵峰值箍缩电流、内爆时间、内爆动能影响很大;在驱动器参数不变,内爆时间不超过电路固有放电周期1/4的前提下,峰值箍缩电流、内爆时间、内爆动能随丝阵质量的增加而增大,内爆时间随丝阵初始半径的增加而增大;在丝阵参数不变时,随着驱动器等效电容的增大,内爆时间减小,丝阵内爆动能增大,但驱动器储能转化为内爆动能的效率却先增大后减小.对于特定的驱动器,优化的丝阵参数应使内爆过程充分利用驱动器固有放电周期的上升沿,使丝阵快速收缩的时间起点接近电路固有放电周期的四分之一,以获得最大的动能效率. 关键词： Z箍缩驱动器 零维内爆模型 模拟行为建模 耦合特性     

一维固-固结构圆柱声子晶体中弹性波的传输特性

利用一维固-固结构圆柱声子晶体中弹性波横向受限的条件,推导出弹性波在其中各个模式满足的关系式,利用它研究了弹性波各模式的特性.并利用转移矩阵研究了弹性波的传输特性随模式量子数和圆柱半径的变化规律.得出了一些一维固-固结构圆柱声子晶体的新特征,即弹性波的传输特性由模式量子数和圆柱半径决定. 关键词： 圆柱声子晶体 弹性波 受限 模式     

Correlation lengths in quasi-one-dimensional systems via transfer matrices

ABSTRACT

Using transfer matrices up to next-nearest-neighbour interactions, we examine the structural correlations of quasi-one-dimensional systems of hard disks confined by two parallel lines and hard spheres confined in cylinders. Simulations have shown that the non-monotonic and non-smooth growth of the correlation length in these systems accompanies structural crossovers [Fu et al., Soft Matter 13, 3296 (2017)]. Here, we identify the theoretical basis for these behaviours. In particular, we associate kinks in the growth of correlation lengths with eigenvalue crossing and splitting. Understanding the origin of such structural crossovers answers questions raised by earlier studies, and thus bridges the gap between theory and simulations for these reference models.     

Effective responses of nonlinear elliptic cylindrical composites

The higher-order dielectric responses of composites composed of weakly nonlinear elliptic cylindrical inclusions randomly embedded in linear media are investigated. The general formulae for effective DC coefficients are newly derived by the average field method up to the ninth order and then applied to analyze the effects of inclusion shapes on the effective response. The results are directly transformed to the quasi-static AC response of the composites under the sinusoidal external electric field with fundamental and third harmonic frequencies. The more general relationships between the effective DC and AC coefficients are established up to the seventh order and third harmonic, which are applicable to all weakly nonlinear isotropic composites.