金刚石磨粒/Cu-Sn-Ti合金/金属胎体复合节块界面微结构

采用铜锡钛(Cu-Sn-Ti)合金钎料分别利用两种常规钎焊方法进行金刚石磨粒预钎焊处理试验并制备复合节块.通过静压强度试验测试了预钎焊磨粒的静压强度,通过三点抗弯试验测试了复合节块的强度,并使用扫描电镜、能谱仪、X型射线衍射仪分析预钎焊金刚石磨粒和复合节块断口的微结构.结果表明:真空炉中预钎焊后金刚石磨粒表面形貌较好,Cu-Sn-Ti合金钎料与金刚石在预钎焊过程中发生了界面元素扩散,形成化学结合界面,Cu-Sn-Ti合金钎料对金刚石的热损伤较小;预钎焊金刚石磨粒的体积浓度为10; ～40;时复合节块抗弯强度达到791MPa以上,高于常规金刚石节块强度;预钎焊金刚石磨粒与金属胎体在烧结过程中发生了界面元素扩散,形成冶金结合,复合节块界面结合强度高.     

Embedding copper nanoparticle-anchored conductive nano-blocks in polyelectrolyte

Conductive carbon nanotubes （CNTs） or alternatively polyaniline （PANI） nano-blocks was introduced into aqueous solutions of polyvinyl alcohol （PVA） and copper （II） salt, to assist the reduction of copper （II） ions and the anchoring of the resulting copper nanoparticles onto the conductive blocks. The mixture solutions of nano-blocks, copper （lI） salts and PVA were spin-coated onto the cathode surface, forming swollen cathode films （SCFs）. The copper （II） ions in the film assembled onto the surfaces of the conductive blocks and were then reduced under an appropriate voltage. It is important that the copper nanoparticles grew only on the surfaces of the conductive blocks. PVA which acted as the matrix of the composites played a role in stabilizing the resulting copper nanoparticles. Morphologies of these polymeric composite films were studied by various characterization methods. Moreover, the mechanism of migration of copper （II） ions, the formation of these polymeric composites, and the overall procedure were investigated in detail.     

线性互补问题基于模同步块多重分裂方法的收敛性

通过利用不动点迭代来研究线性互补问题,根据基模同步多重分裂迭代方法将其线性互补问题的系数矩阵是点的形式推广到块H+的形式,并且分析了当系数矩阵是块矩阵时线性互补问题解的收敛情况。     

Designing shielded radio-frequency phased-array coils for magnetic resonance imaging

In this paper, an approach to the design of shielded radio-frequency (RF) phased-array coils for magnetic resonance imaging (MRI) is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coil’s winding pattern, the selection of a penalty factor is discussed in detail.     

改进的节块展开方法求解圆柱几何对流扩散方程

为高效求解球床高温气冷堆物理-热工耦合问题,发展改进节块展开法求解圆柱几何下的对流扩散方程.针对圆柱几何和对流扩散方程的特殊性,采用三阶多项式和指数函数作为r向横向积分方程的展开函数,在节块展开法的框架下高效求解对流扩散方程.数值验证表明,改进的节块展开方法具有固有的迎风特性,在使用粗网节块时依然能保持稳定性和较高的计算精度.     

调节索氏抽提器抽提液量的2种措施

介绍了调节索氏抽提器抽提液量的2种措施,第1种是在原有提取管中加一可置入玻璃垫块的框架,第2种是在提取管壁上设置可搁置玻璃垫块的支撑凸点.2种措施均通过增减玻璃垫块的数量来调节抽提液量.     

激光陀螺旋转惯导系统IMU的磁屏蔽设计及优化分析

为了提高激光陀螺旋转惯导系统的环境适应性,需要对惯性测量单元(IMU)进行磁屏蔽设计。对IMU的磁屏蔽效率进行了理论计算和有限元仿真,对磁屏蔽材料的厚度、接缝宽度及接缝处贴片的大小等参数进行了仿真分析。利用赫姆霍兹线圈对IMU进行了磁敏感性测试,实验结果表明:设计的IMU磁屏蔽结构的屏蔽效率在23～30 dB范围内,磁场引起的三个激光陀螺漂移小于0.002°/h/mT,满足高精度单轴旋转惯导系统的实用要求。该方法对旋转惯导系统的结构设计及磁屏蔽设计具有一定的参考意义。     

HIAF BRing及高能外靶实验终端的辐射屏蔽设计

强流重离子加速器（HIAF）是中国科学院近代物理研究所自主研制的一台高能强流重离子加速器,它可以实现p到U的全离子加速。为了保证HIAF运行时的辐射安全,针对该装置的增强器（BRing）及高能外靶实验终端,利用蒙特卡洛程序FLUKA及外推法计算得到了加速p,C及U三种离子时所需的辐射屏蔽。结果表明,加速质子时所需屏蔽厚度最大,并以此为依据给出了全地下结构的屏蔽设计。在此基础上,提出了一种估算高能质子/重离子加速器束流均匀损失时横向屏蔽厚度的方法。结果显示,估算结果与FLUKA计算结果符合较好,验证了该方法的有效性和准确性。High Intensity heavy-ion Accelerator Facility (HIAF) is designed by the Institute of Modern Physics, Chinese Academy of Sciences, which can accelerate particles from proton up to uranium. To guarantee the radiation safety of HIAF during operation, the FLUKA code and extrapolation method were adopted to calculate the shielding thickness. The calculations were based on proton, carbon and uranium particles when losing on the Booster Ring (BRing) and the high-energy experimental terminal. The results indicate that the shielding thickness required for accelerating protons was the largest. Basing on the results, a method for estimating the lateral shielding of a high-energy proton/heavy-ion accelerator was proposed. A good agreement shows between the estimated results and the FLUKA calculated results, the validity and accuracy of the method were verified.     

基于图像块能量梯度的多聚焦图像融合

针对多聚焦图像,提出一种基于图像分块的融合方法。将源图像分为大小相同数量相等的子块,采用能量梯度算子作为对焦评价函数,计算各个图像子块能量梯度匹配度,设置匹配度阈值分离出源图像中的清晰区域。源图像中的清晰区域直接作为融合图像相应的区域,其它区域的处理中,构造与相应子块能量梯度大小相关的图像序列,以及像素点到各个子块中心距离相关的融合函数,然后用融合函数对图像序列融合。实验结果表明该方法有效性和合理性。     

电子垂直入射电离氦原子碰撞机理的理论研究

用3C模型和修正后的3C模型在低能、两个出射电子等能分享几何条件下,对电子垂直入射碰撞电离氦原子的三重微分散射截面进行了理论计算,并把计算结果与实验测量结果进行了比较,系统研究了(e,2e)反应中各种屏蔽效应对氦原子三重微分散射截面的影响,同时对截面中形成各峰的碰撞机理做了详细的探讨.研究结果表明:在入射能较低时,各种屏蔽效应对氦原子的三重微分散射截面幅度以及角分布均存在一定影响,并且形成各峰的碰撞机理直接影响截面的变化规律.