低合金结构钢及其焊缝热影响区的韧性损伤演化行为

采用损伤力学方法研究了低合金结构钢及其焊缝热影响区近缝粗晶区的韧性损伤演化行为。从不可逆热力学出发，建立了一般韧性损伤模型。然后用一种新的交流电住损伤测量系统，测得了该钢及其模拟粗晶区的韧性损伤演化规律，得出了相应的损伤演化方程。讨论了应力三轴度对损伤演化和破坏的影响。结果表明，粗晶区及其母材的损伤分别遵循非线性和线性规律；前者的损伤生长速度远高于后者，但其临界损伤值和断裂应变远低于后者。     

单向拉伸界面裂纹的条形损伤－塑性区域模型

本文提出单向拉伸情况下两相介质界面裂纹的条形损伤－塑性区域模型。假设在塑性区端点的应力有界，且使弱相介质达到屈服，损伤区的尺寸和δ＝成正比的条件；可确定损伤区与塑性区的长度及其上的法向和切向接合力，ＣＴＯＤ值等。由此导出的裂尖应力场无ｒ￣（－１／２＋ｊｅ）的强奇异振荡，位移场无ｒ￣（１／２＋ｉｅ）的振荡项。     

纵向涡对近壁湍流结构的影响

在封闭水槽中用氢气泡方法观察了纵向涡对近壁湍流结构的影响，涡的下洗侧出现了展向距离较宽、流动较稳定的快斑区，流向速度快；涡的上洗侧出现了含有慢斑的区域，流动结构复杂，流向速度慢，纵向涡使下洗侧速度较快的流体流向壁面，使上洗侧速度较慢的流体远离壁面。     

单层组合型双曲扭网壳静动力特性分析

作者对常见单层组合型扭网壳的结构性状进行了较为详细的研究,经过大量计算,研究了影响网壳结构静力和动力性状的多种因素,从而得出了组合型扭网壳不同于其它网壳的显著特点,本文的结论可供扭网壳的研究和设计参考。     

Salt‐assisted acetonitrile extraction and HPLC‐QTOF‐MS/MS detection for residues of multiple classes of pesticides in human serum samples

Detecting pesticide residues in human serum is a challenging process. In this study we developed and validated a method for the extraction and recovery of residues of multiple classes of pesticides from serum using one reagent. Salt‐assisted acetonitrile extraction and high‐performance liquid chromatography with quadrupole time of flight tandem mass spectrometry were used to quantitate 34 pesticides classified in nine groups of chemicals in human serum samples, which are frequently detected in food. The recoveries for 33 of analyzed pesticides ranged from 86 to 112% with relative standard deviations below 15%. The limits of quantitation and linearity of 31 of the pesticides were 1 µg/L and >0.990, respectively. The lower limit of quantitation has been reported in the literature particularly for multi‐classes pesticide mixtures in human serum. The salt–acetonitrile reagent was allowed to achieve good recoveries and detection limits, which could be attributed to salt altering the solvent polarity, preferentially collecting the organic phase in the solution, and promoting the extraction. The developed method was applied for two organophosphate pesticide metabolites, diethylphosphate and 3,5,6‐trichloro‐2‐pyridinol, in serum from rats that were fed a nonlethal quantity of chlorpyrifos. The concentrations of these two were 252.18 ± 15.47 and 0.63 ± 0.23 µg/L, respectively.     

Photoelectrochemical properties of MWCNT-TiO2 hybrid materials as a counter electrode for dye-sensitized solar cells

The MWCNT-Ti02 hybrid materials were prepared by a simply mixing method and used as a counter electrode （CE） for dye-sensitized solar cells. Compared with the platinum CE, MWCNT-TiO2 CE has the similar redox voltage and current response in the cyclic voltammetry. The electrochemical catalytic activity was characterized by the electrochemical impedance spectroscopy and Tafel curve, including the equivalent circuit, the exchange current density, the limiting diffusion current density, and the diffusion coefficient of triiodide/iodide redox species. The results indicate that the reduction process from triiodide to iodide is determined by the kinetic-controlled and diffusion-limited processes. The device performance is optimal based on the MWCNT-TiO2 （mass ratio of 2：1） CE, such as the open-circuit voltage of 0.72 V, the short-circuit photocurrent density of 15.71 mA/cm2, the fill factor of 0.68, and the photon-to-electron conversion efficiency of 7.69%.     

808 nm大功率半导体激光器阵列的优化设计

采用激射波长为808 nm的GaAs/AlGaAs梯度折射率波导分别限制单量子阱结构外延片,制备了沟道深度不同的半导体激光器阵列,并对载流子分布进行理论分析和模拟。理论和实验结果表明：引入脊形台面和隔离沟道后,激光器阵列的输出功率、电光转换效率、斜率效率和光谱特性均有显著提高。随着沟道的加深,对电流侧向扩散的限制作用增强,从而提高了阵列性能。     

基于前后向迭代法的3维标量激光漫反射特性

针对激光点对点通信方式的不足,提出了利用海面作为激光漫反射媒介进行组网通信的设想,并对激光入射理想导体表面后产生的散射场进行了的研究。首先利用3维标量锥形波对入射激光束进行了模拟;然后列出了积分方程,并根据矩量法进行了离散;最后通过前后向迭代法求解矩阵方程,得出了3维散射系数,准确地表示了基于理想导体界面的3维标量激光漫反射特性。     

碳气凝胶及活化碳气凝胶电极材料制备与性能

以间苯二酚(R)-甲醛(F)为原料,制备了有机气凝胶和碳气凝胶,并对其进行二氧化碳活化。X射线衍射(XRD)测试表明,二氧化碳渗入到碳气凝胶网络结构发生反应,造成(002)峰和(100)峰减弱;扫描电子显微镜(SEM)测试表明,活化没有破坏碳气凝胶的骨架结构,而是增加了大量的nm尺度微孔,从而大大提高了碳气凝胶的比表面积和微孔比例。在1 mol/L KOH电解液中进行了循环伏安和计时电位扫描测试,电极材料电化学性能稳定,具有较好的可逆性,在1 mA/s电流密度下进行充放电测试,得到活化前电极比电容为103 F/g,活化后由于比表面积的增加,比电容达到371 F/g,是一种理想的电化学电极材料。     

低能质子回旋加速器内部束流测量探头的感生放射性

为满足回旋加速器内部束流测量探头产生低放射性的要求,通过理论分析和蒙特卡罗模拟方法,研究了11 MeV,50 μA质子束轰击铜探头产生的感生放射性,得到各种感生放射性核素的饱和放射性活度,并对结果进行了比较。分析结果表明,采用软件FLUKA进行蒙特卡罗模拟,核反应考虑完全,可同时计算不同照射时间下的直接和间接感生放射性,计算结果准确。应用该方法,质子束轰击不同测量探头产生的感生放射性可以得到详细和准确的分析和预测。