Development of a China test cryomodule for ILC

Research and development of a 1.3 GHz 9-cell cavity test cryomodule were carried out by a collaboration group between IHEP (Institute of High Energy Physics) and TIPC (Technical Institute of Physics and Chemistry) in China. The cryomodule is a "test model" for the ILC cryomodule, and a key component of a superconducting accelerator test unit which will be built in the near future, also can be used as a horizontal test facility for 1.3~GHz 9-cell cavities. This paper presents the development status of the cryomodule, including structure design, cryogenic flow diagram, thermal and mechanical simulations, heat load estimation and etc.     

Comparison of Nd:YAG Ceramic Laser Pumped at 885nm and 808nm

Laser performance of 1064 nm domestic Nd：YAG ceramic lasers for 885 nm direct pumping and 808 nm traditional pumping are compared. Higher slope efficiency of 34% and maximum output power of 16.5 W are obtained for the 885nm pump with a 6ram length 1 at.% Nd：YAG ceramic. The advantages for 885nm direct pumping are discussed in detail. This pumping scheme for highly doping a Nd：YAG ceramic laser is considered as an available way to generate high power and good beam quality simultaneously.     

底物中硅原子对苦杏仁醇腈酶催化不对称转氰反应的影响

 对比研究了不同条件下苦杏仁醇腈酶催化乙酰基三甲基硅烷及其碳结构类似物3,3-二甲基-2-丁酮的转氰反应. 结果表明,苦杏仁醇腈酶催化乙酰基三甲基硅烷转氰反应的初速率及对映体选择性均高于其碳结构类似物在同一条件下的对应值. 动力学研究结果表明,苦杏仁醇腈酶催化乙酰基三甲基硅烷转氰反应的表观动力学参数为Km=27.12 mmol/L和vmax=7.05 mmol/(L·h),活化能为51.92 kJ/mol. 苦杏仁醇腈酶催化3,3-二甲基-2-丁酮转氰反应的表观动力学参数为Km=146.58 mmol/L和vmax=2.52 mmol/(L·h),活化能为75.04 kJ/mol. 根据硅原子的特性及酶反应机理合理解释了实验结果.     

抗氧化微量元素与心血管疾病的防治

综述了硒、锌、铜等微量元素与心血管疾病存在相关性的各项动物及临床干预试验。许多研究证明,通过参与抗氧化酶的构成及自身作用或协同作用,抗氧化微量元素能抵御脂质过氧化物的堆积,降低血小板的聚集性,从而与抗氧化维生素一起防止心血管疾病的发生。     

常见连续型统计分布的一点注记

正态分布是概率论与数理统计中最重要的一个分布,本文讨论了常见的连续型统计分布与标准正态分布间的关系,结果表明:几乎所有的常见连续型统计分布都是标准正态分布的函数.     

High Frequency PMN-PT 1-3 Composite Transducer for Ultrasonic Imaging Application

Development of PMN-PT single crystal/epoxy 1-3 composites for high-frequency ultrasonic transducers application is presented. The composite was fabricated by using a DRIE dry etching process with a 45% volume fraction of PMN-PT. A 35 MHz ultrasound flat transducer was fabricated with the composite, which was found to have an effective electromechanical coupling coefficient of 0.81, an insertion loss of 18 db, and a -6 dB bandwidth as high as 100%. Tungsten wire phantom image shows that the transducer had an axial resolution of 30 μm, which was in good agreement with the theoretical expectation. The initial results showed that the PMN-PT/epoxy 1-3 composite has many attractive properties over conventional piezoelectric materials for medical imaging applications.     

Mn(SiO2)3(M=Fe,Co,Ni;n=1-3)团簇的几何结构、光电性质及磁性

基于密度泛函理论中的广义梯度近似系统研究M_n(SiO₂)₃(M=Fe,Co,Ni;n=1-3)团簇的几何结构、光电性质和磁学性质.结果表明:Fe,Co原子相对于Ni原子更易于在(SiO₂)₃团簇上聚集;通过分析团簇的分裂途径及其产物,发现稳定性较好的氧化硅是一种很好的用于负载过渡金属"岛膜"的载体材料;M_n(SiO₂)₃团簇的能隙恰好位于近红外光谱范围内.通过磁性分析发现,该复合团簇的磁矩主要局域在过渡金属原子周围,而且,Fe₂(SiO₂)₃和Co₃(SiO₂)₃具有相对较大的磁矩,这主要源于过渡金属原子的d轨道间相互耦合.能隙和磁性两方面性质进一步肯定了二氧化硅磁性复合材料在医学界被用作光动力靶向治疗的可观前景.     

基于模块化外包的项目调度问题研究——以三峡工程TCP/C1-3-1A-1项目为例

全球化下的市场竞争促使企业在全球范围进行资源整合,外包决策由此成为影响项目调度的重要因素。以三峡三期工程TCP/C1-3-1A-1项目为例,运用设计结构矩阵构建了模块化项目网络,并分两个层次对外包模块进行初选,在此基础上建立了基于模块化外包的项目调度模型。求解结果表明,由于模块化外包消除了承包商的资源瓶颈,降低了资源闲置率,并由此产生了良好的协同效应,因此可以有效地提高项目收益,并大大压缩项目工期。     

One-pot Copper Nanoparticle-catalyzed Synthesis of Imidazo[1,2-α]pyridines Under Solvent-free Conditions

A direct and efficient approach to synthesize imidazo[1,2-α]pyridines through three-component one-pot reaction of 2-aminopyridine,aldehyde and terminal alkyne catalyzed by Cu-nanoparticles under solvent-free conditions has been developed.This method provides a rapid access to substituted imidazo[1,2-α]pyridines with good yields（up to 85％）.     

激光扫描匹配方法研究综述

激光扫描匹配是利用激光雷达进行导航、定位与地图构建的基础,本文对各类激光扫描匹配方法进行了综述。将现有方法归纳为基于点的扫描匹配方法、基于特征的扫描匹配方法和基于数学特性的扫描匹配方法 3类,系统总结了相应类型的常见方法;对典型的算法及其改进算法进行了梳理,并指出了存在的主要问题和发展趋势;介绍了激光扫描匹配方法性能评价和对比的最新研究进展,最后,展望了激光扫描匹配技术未来的研究方向。