爆轰法合成碳包覆镍纳米颗粒的研究

 采用自制的负氧平衡复合炸药前驱体,在密闭容器中充氮气保护下爆轰合成了碳包覆镍纳米颗粒。利用X射线衍射、X射线荧光、透射电镜和拉曼光谱等技术,对爆炸产物的组成成分、结构形貌等进行了观测。结果表明,爆轰产物主要由具有面心立方结构的镍晶核和碳元素构成,此外还含有其它微量元素;合成的纳米颗粒呈球形或椭球形状,颗粒尺寸主要分布在10~25 nm范围,包覆的碳壳厚度约1~2 nm,核壳结构完备。结合观测结果,对爆轰法合成碳包覆纳米颗粒的形成机制进行了简单的讨论。     

关于超音速多普勒效应的思考

超音速多普勒效应由于其不便于测量,基本停留在纯理论分析阶段,导致人们产生了一些错误的观点.本文通过逻辑分析、计算机软件模拟等手段,对超音速多普勒效应的音频时序进行了分析研究,找出了错误观点产生的原因,作出了相应的解释,并对错误观点进行了修正,提供了解决方案.     

一类非线性波动方程位势井深度函数的连续性

本文研究一类非线性波动方程位势井深度函数的连续性.通过引入位势井深度函数并给出其性质,给出了位势井深度函数连续性的证明.而位势井深度函数连续性保证了在其基础上得到的位势井族有意义.     

结构抗震计算不同方法之对比研究

利用有限元软件ANSYS对3种不同层高的钢框架模型进行同等烈度条件下抗震分析, 并进行 底部剪力法、反应谱法和时程分析法的对比研究, 得到相应位移应力曲线、3种抗震计算方 法各自的特点及适用条件. 通过观察时程曲线和震动动画过程, 可使学生对抗震计算有直观 认识和深入理解.     

爆炸焊接界面波的数值模拟

借助动力学分析软件ANSYS/LS-DYNA 11.0,运用光滑粒子流体动力学方法(SPH方法),建立以Johnson-Cook材料模型和Grüneisen状态方程为基础的热塑性流体力学模型,对同种钢板爆炸焊接界面波进行了数值模拟.结果表明,运用SPH方法可以得到清晰的爆炸焊接界面波形貌.与实验结果的比较表明:模拟误...     

舰船辐射噪声模拟发射系统的设计研究

本文依据典型舰船噪声的频谱特性规律,设计研制了一套舰船辐射噪声发射系统实验样机,包括信号结构设计、换能器选择配置、系统构成设计等,本噪声模拟发射系统具有100Hz～16kHz频带噪声的模拟发射功能,包括线谱、连续谱成分,频谱分配和谱线形式可调可控,信号总声源级动态范围达60dB。     

GISAXS and SAXS studies on the spatial structures of Co nanowire arrays

The spatial structures of magnetic Co nanowire array embedded in anodic aluminium membranes were investigated by grazing incidence small angle X-ray scattering (GISAXS) and conventional small angle X-ray scattering (SAXS) techniques. Compared with SEM observation, the GISAXS and SAXS measurements can get more overall structural information in a large-area scale. In this study, the two-dimensional GISAXS pattern was well reconstructed by using the IsGISAXS program. The results demonstrate that the hexagonal lattice formed by the Co nanowires is distorted (a ≈ 105 nm, b ≈ 95 nm). These Co nanowires are isolated into many structure domains with different orientations with a size of about 2 μm. The SAXS results have also confirmed that the nanopore structures in the AAM can be retained after depositing Co nanowires although the Co nanowires can not completely but only just fill up the nanopores. These results are helpful for understanding the global structure of the Co nanowire array.     

Study of radiation background at the north crossing point of the BEPCⅡ in collision mode

Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.     

Fast computation of observed cross section for ψ′ → PP decays

It has been conjectured that the relative phase between strong and electromagnetic amplitudes is universally -90° in charmonium decays. ψ′ decaying into a pseudoscalar pair provides a possibility to test this conjecture. However, the experimentally observed cross section for such a process is depicted by the two-fold integral, which takes into account the initial state radiative (ISR) correction and energy spread effect. Using the generalized linear regression approach, a complex energy-dependent factor is ...