双屈服面法测量金属材料动高压屈服强度的若干改进

在J.R.Asay等提出的双屈服面法（简称AC方法）测量动态屈服强度的基础上,对实验设计和数据处理做了部分改进。在实验设计方面,在满足实验物理设计的前提下,将 AC方法的卸载实验装置(双层飞片和双台阶样品)简化为单飞片和单台阶样品,以简化波系作用,并减少了声速测量不确定度的引入因素。在数据处理方面,发现由Lagrange声速和工程应变关系曲线外推求预冲击态的体积声速容易引入较大的不确定度,而通过Lagrange声速和粒子速度关系曲线可以更清晰地得到塑性卸载起始点,使图解法和积分法得到的屈服强度值趋于一致。利用改进后的AC方法,得到了低温退火后LY12铝在20.0 GPa预冲击压力下的屈服强度为0.6 GPa。     

分段爆破地震强度的试验研究

在爆破实验中,通过调整段数、分段炸药量、炸药总量、间隔时间、孔网参数、岩石波阻等爆破相关因素,以改变各分段爆破地震波持续时间、段别间爆破地震波重叠程度来研究爆破地震强度与爆破相关因素间的相互关系。阐明了爆破地震波传播规律及其破坏行为特征,以及各个爆破相关因素对爆破地震强度的影响程度。获得了确定段数等爆破参数的规则,从而为生产实践设计最佳爆破参数提供理论依据。     

The Maximal Graded Left Quotient Algebra of a Graded Algebra1)

We construct the maximal graded left quotient algebra of every graded algebra A without homogeneous total right zero divisors as the direct limit of graded homomorphisms （of left A-modules） from graded dense left ideals of A into a graded left quotient algebra of A. In the case of a superalgebra, and with some extra hypothesis, we prove that the component in the neutral element of the group of the maximal graded left quotient algebra coincides with the maximal left quotient algebra of the component in the neutral element of the group of the superalgebra.     

中国海洋经济可持续发展能力省际空间差异研究——基于组合综合评价方法

海洋经济可持续发展是实现海洋经济强国发展战略的重要手段,定量评价海洋经济可持续发展水平及其特征是合理开发海洋资源、发展海洋经济的重要保证.在构建我国海洋经济可持续发展能力评价指标体系基础上,运用组合综合评价方法定量分析我国11个沿海地区海洋经济可持续发展类型及其发展对策.     

流体力学半径对估算胶体微球聚集速率常数的影响

胶体粒子聚集速率常数实验值远低于理论值一直是被普遍关注的问题.聚集速率常数的理论推导是基于粒子的几何半径来考虑的,但决定粒子扩散速率及聚集速率的应该是粒子的流体力学半径(大于几何半径),因而它是使聚集速率常数实验值低于理论值的因素之一.影响流体力学半径的因素很多,其中,带电粒子在溶液中因表面存在双电层,会明显增大流体力学半径,造成聚集速率减慢.而双电层的厚度又随溶液中离子强度的不同而改变.本工作在聚集速率的公式中引入了修正因子,即几何半径与其流体力学半径之比,以修正由于用几何半径代替流体力学半径带来的误差.其中几何半径和流体力学半径可以分别用扫描电镜(SEM)和动态光散射(DLS)来测定.以两种粒径的聚苯乙烯带电微球为例,考察了在不同离子强度下,该误差的大小.结果发现,对于半径为30 nm的微球,用流体力学半径计算的慢聚集速率常数比理论值偏低约8%.该误差随离子强度增加而减少.对于快聚集情况,流体力学半径对聚集速率基本没有影响.     

用模糊集方法计算工程质量等级确定质量系数

采用工程模糊集理论方法,用科学合理的数字来衡量工程质量.提出将专家定量评分法与定性评议法科学地统一起来,使权重的确定更为合理与科学.同时,用实例进行实证分析.     

Limits on light emission from silicon

Although silicon is an indirect semiconductor, light emission from silicon is governed by the same gener- alized Planck＇s radiation law as the emission from direct semiconductors. The emission intensity is given by the absorptance of the volume in which there is a difference of the quasi Fermi energies. A difference of the Fermi energies may result h＇om the absorption of external light （photoluminescence） or from the injection of electrons and holes via selective contacts （electroluminescence）. The quantum efficiency may be larger than 0.5 for carrier densities below 10^15 cm^-3. At larger densities, non-radiative recombination, in particular Auger recombination dominates. At all carrier densities, the relation between emission intensity and difference of the quasi Fermi energies is maintained. Since this difference is equal to the voltage of a properly designed solar cell, luminescence is the key indicator of material quality for solar cells.     

Bonding Interface Imaging and Shear Strength Prediction by Ultrasound1

The propagation of a longitudinal ultrasonic wave normally incident upon an adhesively bonded structure is stud- ied. The structure consists of adherend and adhesive layers with finite thickness. Interfaces between adherend and adhesive are regarded as distributed springs. Theoretical and experimental results show that resonant frequencies of the bonded structure vary sensitively with the interface stiffness constants and adhesive thickness, and these interface characteristics are inversed by the simulation annealing （SA） method. Furthermore, the distribution image of interface stiffnesses is compared with the state of fracture interface, and quantitative prediction of shear strength is achieved based on the distribution of interface stiffnesses and adhesive thicknesses by using a back- propagation neutral network. The average relative error of the shear strength from prediction to real value is 10.7%.