刚性弹丸撞击下岩石侵彻之理论研究

 对岩石在刚性弹丸撞击下的侵彻问题进行了理论研究。文章包括两个部分。首先,对常用的预测岩石在刚性弹丸撞击下侵彻深度的方程进行了简单回顾和评论;然后,在实验观测的基础上,对最近发表的一些预测在刚性弹丸撞击下,混凝土和土壤的侵彻公式进行了修正,推导出一个较为合理的剪切强度表达式。拟合结果表明：该模型与Frew、Forrestal和Hanchak所得到的石灰岩侵彻的实验数据吻合得很好。     

多原子分子力场的量子化学研究

本文报道了一种由量子化学方法获得的笛卡尔力场F_x矩阵转换成内坐标力场F_r矩阵的方法。利用该方法获得的力场和Wilson-GF矩阵方法对多原子分子和离子的力场、振动模式和频率进行了研究,获得了十分满意的结果。     

ICP-MS multielemental determination of metals potentially released from dental implants and articular prostheses in human biological fluids

A sector field high-resolution (HR)-ICP-MS and an octapole reaction system (ORS)-ICP-MS have been compared for the simultaneous determination of traces of metals (Ti, V, Cr, Co, Ni, and Mo) released from dental implants and articular prostheses in human biological fluids. Optimum sample treatments were evaluated to minimize matrix effects in urine and whole blood. Urine samples were diluted tenfold with ultrapure water, whereas whole blood samples were digested with high-purity nitric acid and hydrogen peroxide and finally diluted tenfold with ultrapure water. In both matrices, internal standardization (Ga and Y) was employed to avoid potential matrix interferences and ICP-MS signal drift. Spectral interferences arising from the plasma gases or the major components of urine and whole blood were identified by (HR)-ICP-MS at 3,000 resolving power. The capabilities of (HR)-ICP-MS and (ORS)-ICP-MS for the removal of such spectral interferences were evaluated and compared. Results indicate that polyatomic interferences, which hamper the determination of such metallic elements in these biological samples, could be overcome by using a resolving power of 3,000. Using (ORS)-ICP-MS, all those elements could be quantified except Ti and V (due to the polyatomic ions ³¹P¹⁶O and ³⁵Cl¹⁶O, respectively). The accuracy of the proposed methodologies by (HR)- and (ORS)-ICP-MS was checked against two reference materials. Good agreement between the given values and the concentrations obtained for all the analytes under scrutiny was found except for Ti and V when analyzed by (ORS)-ICP-MS.     

Matrix effects during phosphorus determination with quadrupole inductively coupled plasma mass spectrometry

A quadrupole inductively coupled plasma mass spectrometer was evaluated for use in the detection of phosphorus. The influences of nitric acid and methanol (simulating the composition of a sample solution after nitric acid digestion) on phosphorus determination were studied using two different measuring methods at different plasma conditions: detection of phosphorus ions at m/z 31 and detection of phosphorus oxide ions at m/z 47. The existence of polyatomic interferences at m/z 31 and 47 was explored. Nitric acid and methanol are shown to be the sources of polyatomic ions and therefore cause poorer detection limits. Better detection limits were achieved in such matrices when phosphorus was detected as ³¹P⁺. The presence of methanol improves the system sensitivity towards phosphorus sevenfold; however, this positive effect is hindered by the high background signal due to carbon-based polyatomic ions. For samples with an organic matrix an appropriate mineralization procedure should be applied (high excess of nitric acid and high temperature) to quantitatively oxidize organic compounds to carbon dioxide, which is easily removed from the sample, in order to achieve correct results.     

Polyatomic gases with dynamic pressure: Kinetic non-linear closure and the shock structure

This paper is concerned with the analysis of polyatomic gases within the framework of kinetic theory. Internal degrees of freedom are modelled using a single continuous variable corresponding to the molecular internal energy. The state of the gas is determined by the 6 fields—5 standard fields (mass density, velocity and temperature) and the dynamic pressure. Using the maximum entropy principle and the non-equilibrium entropy density, it is shown that dynamic pressure appears as a natural measure for deviation from equilibrium state. A proper collision cross section is constructed which obeys the micro-reversibility requirement. The non-linear source term in the balance law for dynamic pressure, and the entropy production rate, are determined using collision operator in the form which generalizes the known results obtained within the framework of extended thermodynamics. They are also compared with the results obtained using BGK approximation. For the proposed model the shock structure problem is thoroughly analyzed and discussed for different values of the parameters in the source term.     

旋转弹空气动力学

本文叙述了旋转弹空气动力学的形成和研究内容;评述了它的研究进展,其中包括我们自己的理论与实验成果;阐述了与旋转弹气动设计有关的几个问题;指出了值得注意的研究动向.      

等离子体质谱法测定地质样品中痕量稀土元素的基体效应及多原子离子干扰的校正研究

采用模拟地质样品中稀土元素间天然组成比的基体匹配校正标准溶液进行外标校正,有效地抑制了地质样品分析中的基体效应;以¹¹⁵In-¹⁰³Rh双内标元素校正,监控和校正分析信号的短期和长期漂移;通过单个稀土元素及钡的氧化物、氢氧化物的测定计算出等效的干扰浓度,进而校正了稀土元素分析中多原子离子干扰.建立了地质样品中痕量稀土元素测定中基体效应及多原子离子干扰的校正方法,通过对5个标准参考物质的分析,定量测定限为0.0090.133μg·g^-1,RSD小于5%.     

动态反应池-电感耦合等离子体质谱法测定土壤中重金属元素

用微波消解/动态反应池-电感耦合等离子体质谱法测定土壤中的重金属。研究了微波消解以及影响测定的因素(多原子离子干扰及盐度等),研究表明:引入动态反应气NH3可有效消除多原子离子干扰;盐度小于2.0 g/L测定结果比较可靠。方法检出限为0.008~0.32μg/L,回收率为92%~109%。已应用于土壤样品的测定。     

Multiple ionization of atoms and molecules impacted by very high-q fast projectiles in the strong coupling regime （q/v 〉 1）

In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime （q/v 〉 1）. The results obtained from this approach are in excellent agreement with the available experimental data. A probable scenario of molecular multiple ionization by fast and very high-q projectiles is discussed. The very small computational time required here and the good agreement with the existing experimental data make it a good candidate for studying the multiple ionization of complex molecules under high linear energy transfers.     

球形弹对金属靶板侵彻问题的数值模拟

基于球形空穴膨胀模型(SCE),采用ABAQUS有限元商业软件并结合自主开发的ABAQUS用户子程序对球形弹侵彻金属靶进行了有限元3D数值模拟。根据空穴膨胀理论,靶体对侵彻弹体的影响可以用一个作用在弹体表面的力函数代替,这样在进行数值模拟时就无需划分靶体网格,也避免了复杂的接触问题,从而使模拟大大简化。模拟过程中考虑到弹体的可变形性和入射时的微小偏航角,并且考虑了弹体在运动过程中和靶体的接触分离效应。模拟结果与文献中的实验结果进行了比较,模拟结果与实验结果吻合得很好。