Liquid-liquid extraction of Pa-233(V) with Aliquat 336

The extraction of protactinium with Aliquat 336 (methyl-tri-caprylyl ammonium chloride) in toluene, cyclohexane and chloroform from HCl, HNO3, H2SO4, HClO4, HF and mixed HCl-HF media was investigated by radioactive tracer technique. Distribution ratios of protactinium between the aqueous solution and the organic phase were determined as a function of shaking time, concentrations of acid in aqueous solution phase, extractant concentration and type of diluents in the organic phase. Aliquat 336 can almost quantitatively extract protactinium from strong HCl solution. At the same time, small amounts of HF in HCl solutions have a strong effect on Pa distribution.

Strain Regularity and Stiffness Tensor of Reinforcers in Dense Particle Reinforced Composites

针对高体积份数、随机分布、等轴状颗粒增强复合材料 ,研究了材料的应变分布规律 ,给出了基体和增强体应变平均值与材料微观结构参数之间的定量关系。结果表明 ,除应变平均值外 ,应变涨落是影响刚度张量的另一个重要因素 ,研究了应变涨落与材料微观结构参数之间的关系 ,并推导出了复合材料的刚度张量。与实验结果和以往的理论比较 ,预测结果与实验结果吻合良好

Thermodynamical versus log-Poisson distribution in turbulence

The thermodynamical model of intermittency in fully developed turbulence due to Castaing (B. Castaing, J. Phys. II France 6 (1996) 105) is investigated and compared with the log-Poisson model (Z-S, She, E. Leveque, Phys. Rev. Lett. 72 (1994) 336). It is shown that the thermodynamical model obeys general scaling laws and corresponds to the degenerate class of scale-invariant statistics. We also find that its structure function shapes have physical behaviors similar to the log-Poisson's one. The only difference between them lies in the convergence of the log-Poisson's structure functions and divergence of the thermodynamical one. As far as the comparison with experiments on intermittency is concerned, they are indifferent.

Measurement Of Fracture Toughness And Interfacial Shear Strength Of Hard And Brittle Cr Coating On Ductile Steel Substrate

The fracture toughness and interfacial adhesion properties of a coating on its substrate are considered to be crucial intrinsic parameters determining performance and reliability of coating-substrate system. In this work, the fracture toughness and interfacial shear strength of a hard and brittle Cr coating on a normal medium carbon steel substrate were investigated by means of a tensile test. The normal medium carbon steel substrate electroplated with a hard and brittle Cr coating was quasi-statically stretched to induce an array of parallel cracks in the coating. An optical microscope was used to observe the cracking of the coating and the interfacial decohesion between the coating and the substrate during the loading. It was found that the cracking of the coating initiated at critical strain, and then the number of the cracks of the coating per unit axial distance increased with the increase in the tensile strain. At another critical strain, the number of the cracks of the coating became saturated, i.e. the number of cracks per unit axial distance became a constant after this critical strain. Based on the experiment result, the fracture toughness of the brittle coating can be determined using a mechanical model. Interestingly, even when the whole specimen fractured completely under an extreme strain of the substrate, the interfacial decohesion or buckling of the coating on its substrate was completely absent. The test result is different from that appeared in the literature though the identical test method and the brittle coating/ductile metal substrate system are taken. It was found that this difference can be attributed to an important mechanism that the Cr coating on the steel substrate has a good adhesion, and the ultimate interfacial shear strength between the Cr coating and the steel substrate has exceeded the maximum shear flow strength level of the steel substrate. This result also indicates that the maximum shear flow strength level of the ductile steel substrate can be only taken as a lower bound estimate on the ultimate shear strength of the interface. This estimation of the ultimate interfacial shear strength is consistent with the theoretical analysis and prediction presented in the literature.

Alternating Starvation Of Dislocations During Plastic Yielding In Metallic Nanowires

Using molecular dynamics simulations, we show that the mechanical deformation behaviors of single-crystalline nickel nanowires are quite different from their bulk counterparts. Correlation between the obtained stress-strain curves and the visualized defect evolution during deformation processes clearly demonstrates that a sequence of complex dislocation slip events results in a state of dislocation starvation, involving the nucleation and propagation of dislocations until they finally escape from the wires, so that the wires deform elastically until new dislocations are generated. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

USED CARS测量对撞式扩散火焰的温度分布

介绍了用USED CARS技术测量对撞式甲烷/空气扩散火焰前滞止区和尾流区的温度分布剖面。在滞止区富甲烷观察到甲烷燃烧前的热解过程；尾流区温度高于滞止区温度，表明在滞止区有未完全燃烧的中间产物存在，在尾流区发现C_2及CH的光谱也证明了这一点。

发泡镍对肺冲击伤的防护效果及其机理研究

本研究采用激波管,探讨了发泡镍对肺冲击伤的防护效果和防护机理。结果表明,发泡镍可明显减轻肺冲击伤的程度,降低死亡率。发泡镍的防护作用可能与其降低冲击波超压峰值、延长正压上升时间和缩短正压作用时间有关。结果提示发泡镍是一种较为理想的冲击伤防护材料。

爆炸力学实验技术新进展

本文综述了爆炸力学实验和测试技术的最新进展。

激光通过湍流剪切层后的光学性质

本文论述一个由流体力学和光学联系起来的新课题——激光通过湍流剪切层后的相位变化及峰值功率变化。描述了流体力学及光学的有关公式,并认为,某些光学公式可以用流体力学参数去关联。对实验装置及图象分析方法加以叙述,并附上一些实验结果及数据处理结果。

岩石力学性质的研究和爆破技术的改进

<正> 一、前言 炸药爆炸后释放出大量能量,通过爆炸产物气体膨胀对岩石做功,能量以波的形式在岩石中传播,引起岩石变形、破坏、抛掷。爆破工程的任务就是要高效率地利用这种能量对岩石造成理想的块度,抛掷的岩石获得一定的初速,不应破坏的则要完整无损。要做到这些,一方面需对爆炸载荷如何引起岩石的变形、运动和破坏进行系统的实验观察,做出正确的理论分析,加深对爆破机理的认识,为爆破的最优设计打下理论基础,另一方面要有把这种理论变成现实,付诸工程实践的相应技术。

数学机械化问题中的向量加工

<正> 1.多项式算法 数学机械化必须首先解决一类数学问题本身的机械化算法问题。作者通过微分方程机械化的实践,并分析了近年来各数学分支领域机械化的结果,认识到这样一个基本事实:相当多一类数学问题的机器定理证明和公式推导,都是对其问题本身寻求代数表示方法,其核心问题最后归结为多项式算法。因此,多项式算法是一个典型的机械化算法。