爆炸应力波与裂纹作用实验研究

为研究爆炸应力波与裂纹相互作用机理,利用透射式爆炸动态焦散线光学实验系统研究了预制水平静态裂纹和切缝药包炮孔爆破产生的水平运动裂纹受正入射爆炸动载作用后动态特性的变化规律。结果表明:正入射爆炸应力波与静止裂纹作用时,爆炸应力波P波使得裂纹先闭合后张开,S波在裂纹壁面形成波浪状散斑上下交替向外扩展;运动裂纹尖端应力场对静止裂纹的起裂和扩展有重要影响。后爆孔爆炸应力波对先爆孔产生的水平定向运动裂纹尖端动力学特性影响显著。当爆炸应力波与运动裂纹同向时,P波使得裂纹扩展速度和应力强度因子KI^d先减小后增大,S波促进了裂纹的扩展,波与裂纹作用之后,裂纹扩展速度增大;当爆炸应力波与运动裂纹反向时,P波抑制了运动裂纹的扩展,波与裂纹作用之后,裂纹扩展速度和应力强度因子KI^d均逐渐降低。     

粤东柘林湾浮游植物与生态因子的灰关联-回归分析

应用灰关联方法对 2 0 0 1年 1 0月至 2 0 0 2年 7月柘林湾海域的海水采样结果进行数据分析 ,在磷酸盐、硅酸盐等 1 1项生态因子中找出影响浮游植物密度的关键因子 .根据这个结果 ,进一步建立了以这些关键因子为自变量的线性回归模型 ,模型最后的分析结果和灰关联分析的结果一致 ,即 Fe、水温、浊度是影响柘林湾浮游植物密度的关键因子 .     

Globalexponential stability of an epidemic model with saturated and periodic incidence rate

This paper is concerned with a SIR model with saturated and periodic incidence rate and saturated treatment function. By using differential inequality technique, we employ a novel argument to show that the disease‐free equilibrium is globally exponentially stable. The obtained results improve and supplement existing ones. We also use numerical simulations to demonstrate our theoretical results. Copyright © 2015 John Wiley & Sons, Ltd.     

高斯光束斜入射法布里-珀罗干涉腔后的反射光强分布

基于多光束干涉原理,推导了高斯光束斜入射法布里-珀罗干涉仪后的反射光强表达式.在此基础之上数值研究了入射角对高斯光束的反射特性的影响.研究结果表明:当法布里-珀罗干涉腔的腔长满足反共振时,随着入射角的增大,反射光的光强分散,峰值强度下降后呈现出幅度衰减的波动;峰值位置随着入射角的增大,呈现出幅度越来越小的振荡偏移;光斑大小随入射角的增大,呈现出幅度减小的振荡.     

双圈拟阵

Sim■es Pereira于1992年提出双圈拟阵.本文讨论了(i)双圈拟阵及其秩函数;(ii)次模函数在双圈拟阵中的应用;(iii)双圈拟阵B(G)的横贯拟阵.主要结果:1°由圈矩阵Bf=[I,Bf12]和圈秩的概念,推出M(f0)为双圈拟阵;2°证明了双圈拟阵B(G)等于由子集族{Av∶v∈V(G)},e与v在G中相关联}所确定的横贯拟阵;3°用不同于Matthews(1977)的方法证明了(iii).     

Radiation damage in polymer films from grazing‐incidence X‐ray scattering measurements

Grazing‐incidence X‐ray scattering (GIXS) is widely used to analyze the crystallinity and nanoscale structure in thin polymer films. However, ionizing radiation will generate free radicals that initiate crosslinking and/or chain scission, and structural damage will impact the ordering kinetics, thermodynamics, and crystallinity in many polymers. We report a simple methodology to screen for beam damage that is based on lithographic principles: films are exposed to patterns of X‐ray radiation, and changes in polymer structure are revealed by immersing the film in a solvent that dissolves the shortest chains. The experiments are implemented with high throughput using the standard beam line instrumentation and a typical GIXS configuration. The extent of damage (at a fixed radiation dose) depends on a range of intrinsic material properties and experimental variables, including the polymer chemistry and molecular weight, exposure environment, film thickness, and angle of incidence. The solubility switch for common polymers is detected within 10–60 s at ambient temperature, and we verified that this first indication of damage corresponds with the onset of network formation in glassy polystyrene and a loss of crystallinity in polyalkylthiophenes. Therefore, grazing‐incidence X‐ray “patterning” offers an efficient approach to determine the appropriate data acquisition times for any GIXS experiment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1074–1086     

K-Theory for the Integer Heisenberg Groups

We give a closed formula for topological K-theory of the homogeneous space N/, where is the standard integer lattice in the simply connected Heisenberg Lie group N of dimension 2n+1, n . The main tools in our calculations are obtained by computing diagonal forms for certain incidence matrices that arise naturally in combinatorics.     

Eight and seven point degenerations of Miquel's Theorem in Laguerre planes

For M?bius planes Schaeffer [9] has proved that all seven point degenerations of Miquel's Theorem characterize miquelian M?bius planes. For Laguerre planes we have several degenerations of Miquel's Theorem with eight and seven points. We prove that all except one of these degenerations characterize miquelian Laguerre planes. The remaining degeneration characterizes elation Laguerre planes. Received 14 September 2001; revised 1 September 2002.     

一种时间分辨三通道软X射线光谱仪

报道了时间分辨的三通道软X射线光谱仪研制工作，重点介绍了研制的三通道能谱仪的工作原理以及210 eV，420 eV和900 eV三个能区的设计参数，谱仪在上海神光Ⅱ高功率激光器三倍频实验中进行了多次实时考核，取得较好实验结果，将多道平面镜、滤光片成功配接于高时间分辨X射线条纹相机上，使该谱仪在亚千电子伏能区内，可同时进行三个波段软X射线的时间和空间分辨测量，提供的实验结果也表明：X射线平面镜结合滤光片的分光技术可应用于高时间分辨的X射线条纹相机上，从而获得高达10 ps的时间分辨. 关键词： 软X射线条纹相机 平面镜 滤光片 掠入射     

Wave propagation in stereo-lithographical (STL) bone replicas at oblique incidence

Comparisons between predictions of a Biot-Allard model allowing for angle-dependent elasticity and angle-and-porosity dependent tortuosity and transmission data obtained at normal incidence on water-saturated replica bones are extended to oblique incidence. The model includes two parameters which are adjusted for best fit at normal incidence. Using the same parameter values, it is found that predictions of the variation of transmitted waveforms with angle through two types of bone replica are in reasonable agreement with data despite the fact that scattering is not included in the theory.