纳米晶CuCr合金的制备及其截流值研究

通过高能球磨和真空热压技术制备了致密度大于98%的纳米晶CuCr合金,通过XRD,SEM和TEM研究了其显微组织和结构.结果表明,其晶粒尺寸小于50 nm.在模拟电路上研究了其真空电弧稳定性和截流值,纳米晶CuCr合金的真空电弧稳定性好于常规CuCr合金,其截流值为常规CuCr合金的17%～35%.     

曲轴用仿SAE1548钢的研制

仿SAE1548钢是在美国SAEJ403-2001标准含锰碳素钢的基础上,对化学成份进行了调整,并规定了多项技术指标形成的一个新钢种,其主要应用于发动机曲轴。此钢种经本钢研制生产三年来在工艺技术等方面取得成功经验。     

High precision magnetometer for geomagnetic exploration onboard of the China Seismo-Electromagnetic Satellite

The China Seismo-Electromagnetic Satellite (CSES) is the first platform of China’s earthquake observation system in space and the first satellite of China’s geophysical field detection missions. The high precision magnetometer (HPM), which contains two fluxgate sensors and a coupled dark state magnetometer (CDSM), measures the vector of the Earth’s magnetic field with a bandwidth from DC to 15 Hz. The two fluxgate sensors are in a gradiometer configuration in order to reduce satellite interferences. Additionally, the CDSM sensor measures the scalar value of the magnetic field with higher accuracy and stability. Several data processing and calibration methods have been prepared to get accurate vector magnetic field data. This includes the calibration of each of the three sensors, the absolute vector correction algorithm, the spacecraft magnetic interference elimination and the coordinate transformation method. Also the instrument performances based on ground calibration activities are shown in this article.     

内压直管对称循环弯曲棘轮效应实验研究

利用多轴疲劳实验机及自行设计的准三点弯曲实验装置，对20钢直管在不同内压与不同循环弯曲载荷下进行棘轮应变测试。棘轮应变由应变计检测，直管径向变形由自行设计的径向位移引伸计检测。实验发现，内压直管在一定循环弯曲载荷作用下，将首先沿环向产生棘轮应变，随着载荷的增加，轴向也将产生棘轮应变，但较环向小。随着棘轮应变的产生，直管圆截面变为椭圆截面。无论是不同试件，还是同一试件的多载荷步实验，均发现相同内压下，循环弯曲载荷增大，棘轮应变速率增大；相同循环弯曲载荷下，内压增大，棘轮应变速率增大。多载荷步加载时，以往棘轮应变会降低应有的棘轮应变速率，尤其在较大的载荷下先发生棘轮应变后，这种影响十分明显。利用直管准三点弯曲实验装置，确定内压直管循环弯曲的棘轮边界。     

子模型技术在大型球罐支撑区应力分析及结构优化中的应用

利用壳到体子模型法对大型球罐U形柱支撑区进行应力分析,保证该区域的计算精度。通过在U形柱内设置加强筋板,改变U形柱的刚度,讨论U形柱刚度对连接区应力状况的影响,发现U形柱刚度越大,球壳与支柱连接处最大应力强度水平越高,而支柱最大应力强度水平越低。基于分析设计的等强度原则,对加强筋板的尺寸及安装位置进行优化设计,使U形柱具有合理的刚度,以保证球壳在支柱支撑处的最大应力强度水平与支柱的最大应力强度水平相近。     

毛细管电动色谱法用于DNA水解产物碱基测定

采用毛细管电动色谱法对小牛胸腺脱氧核糖核酸(DNA)水解产物中各碱基含量进行定量测量.结果表明:四种碱基的检测限均可达到10-6mol/L数量级,符合生物样品中含量测定的要求.     

准等强度原则下压力容器不连续区的优化设计

提出一种压力容器不连续区基于分析设计的准等强度设计原则。以高压球壳接管整体补强锻件为例,建立准等强度原则下的优化数学模型,利用有限元程序ANSYS提供的参数化设计语言APDL及优化模块OPT,进行优化计算,实现压力容器不连续区分析设计意义上的结构优化设计。     

从压力容器有限元分析结果中分解一次弯曲应力的一种方法

在压力容器分析设计中,如何将有限元分析得到的总应力场分解成规范中定义的各类应力是应用中最为关心且必须解决的关键问题.在深入分析基于一次结构的应力分类两步法的基础上,提出利用叠加原理构建一次结构的方法,该方法不必将原有限元模型分割为一次结构,而是根据结构与载荷特点通过适当的分步加载获得一次结构及相应的一次弯曲应力.以与筒体连接的平板封头为例,讨论该方法的实施步骤.与极限载荷分析结果进行比较,文中方法给出结果稍显保守.     

Effect of chain length on the conformation and friction behaviour of DNA

Four double-stranded DNA films with different chain lengths were prepared on 3-aminopropyltriethoxysilane (APS)-modified mica surfaces in the NaCl solution with concentration ranging from 0.001 to 0.1 M. By using an atomic force microscope, the force-distance curves and friction behaviour of each DNA film were studied in the NaCl solution that was used in the sample preparation. When adsorbed on mica as films in salt solution, the conformation of DNA molecules would be a combination of loops and “train-like”. As the chain length increased from 50 to 20000 bp, the extension rate of DNA film increased from 7.1 to 11.5 in 0.001 mol/L NaCl solution, which suggested that the DNA molecule with long chain likely resulted in more extended conformation. In addition, under low normal load, low NaCl concentration could increase the friction of DNA film and the chain length revealed insignificant effect on the friction force of DNA film. Therefore, long chain DNA with low salt concentration is more conducive to the nanopore sequencing process, since extended conformation can make DNA molecules easier to reach into nanopore and the high friction can reduce the translocation speed. These results may benefit the development of the third-generation sequencing technique based on nanopore.     

获取固定管板换热器管板一次弯曲应力的一种方法及其应用

利用载荷分解施加,提出一种构建固定管板换热器管板一次结构、获取一次弯曲应力的方法,一次结构中可保留简体对管板转动的有利多余约束.以一台甲醇合成塔为例,结合非一次结构法设计存在的问题,利用所提出的方法进行了有限元设计计算.计算表明,该方法给出的许用载荷与极限载荷分析法给出的许用载荷相当,方法可行.值得注意的是,如果应力评...