基于四维度因子分析的电缆试验策略研究

本文通过对10k V配网交联乙烯电力电缆故障的主要来源的简述,介绍了某供电局电缆振荡波测试现状,在面对大数量测试对象和有限试验数量的矛盾分析,以问题为导向为原则,从基础数据方面,提出了四维度方式的试验策略,进行实际应用,印证其有效性。

基于异维变异的差分混合粒子群算法

针对粒子群(Particle Swarm Optimization,PSO)算法和差分进化(Differential Evolution,DE)算法存在容易陷入局部极值、进化后期收敛速度慢和收敛精度低的局限性,提出了一种基于异维变异的差分混合粒子群(UDEPSO)算法。首先,为了提高群体多样性,使用熵度量初始化粒子;其次,在粒子迭代的过程中,根据粒子的分布特点,引入异维变异学习策略和维度因子以引导粒子及时跳出局部极值达到最优解;最后,将所提算法在10个典型的测试函数上进行了仿真,其在9个测试函数的收敛精度和标准差上取得了显著的效果,远优于PSO算法、DEPSO算法以及CDEPSO算法。实验结果表明,UDEPSO算法在优化收敛精度和效率上具有较强的优势。

旅游地社区恢复力认知测度与影响因子分析——以千岛湖为例

人是社会—生态系统的主要决定性因素,旅游地社区恢复力提高是旅游地可持续治理的关键。运用通径分析方法,从治理、社会、经济及生态系统4个维度建立社区恢复力认知测度模型,定量测度千岛湖社区认知恢复力,识别脆弱性及应对能力认知对社区恢复力的复杂影响。结果表明:(1)社区恢复力认知可提取8个因子,政府治理在社区恢复力中的作用最为显著,是社区恢复力提高的主导力量。(2)千岛湖恢复力认知综合平均值为2.42,处于中等偏下水平。社会子系统恢复力认知值最高,生态和经济子系统恢复力认知值最低,系统发展应关注生态资本的积累与保护以及经济发展的多样性与稳定性。(3)社区脆弱性、个体和政府应对能力的各变量对社区总恢复力及各维度认知呈现出错综复杂的关系,政府应对能力对总恢复力及各维度认知的影响相对最强,个体应对能力对多数恢复力认知维度未产生明显影响。需进一步发挥个体作用,促进个体和政府的共同参与,提高社区恢复力。

Caustics study of the effect of glass fibres on dynamic fracture of hardened cement paste

The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.

Functional ergodic limits for occupation time processes of site-dependent branching Brownian motions in R

We consider a kind of site-dependent branching Brownian motions whose branching laws depend on the site-branching factor σ（·）. We focus on the functional ergodic limits for the occupation time processes of the models in IR. It is proved that the limiting process has the form of λζ（·）, where A is the Lebesgue measure on R and ζ（·） is a real-valued process which is non-degenerate if and only if cr is integrable. When ζ（·） is non-degenerate, it is strictly positive for t 〉 0. Moreover, ζ converges to 0 in finite-dimensional distributions if the integral of a tends to infinity.

Application of the extended traction boundary element-free method to the fracture of two-dimensional infinite magnetoelectroelastic solid

A novel extended traction boundary element-free method is proposed to analyze the crack problems of two-dimensional infinite magnetoelectroelastic solid.An extended traction boundary integral equation only involving Cauchy singularity is firstly derived.Then,the extended dislocation densities on the crack surface are expressed as the combination of a characteristic term and unknown weight functions,and the radial point interpolation method is adopted to approximate the unknown weight functions.The numerical scheme of the extended traction boundary element-free method is further established,and an effective numerical procedure is used to evaluate the Cauchy singular integrals.Finally,the stress intensity factor,electric displacement intensity factor and magnetic induction intensity factor are computed for some selected crack problems that contain straight,curved and branched cracks,and good numerical results are obtained.At the same time,the fracture properties of these crack problems are discussed.