圆柱涡激振动的结构-尾流振子耦合模型研究

建立了一个新的结构一尾流振子耦合模型, 流场近尾迹动力学特征被模化为非线性阻尼振子, 采用van der Pol方程描述.以控制体中结构与近尾迹流体间受力互为反作用关系来实现流固耦合, 采用该模型进行了二维结构涡激振动计算, 得到了合理的振幅随来流流速的变化规律和共振幅值, 并正确地预计了共振振幅值 A~*_(max) 随着质量阻尼参数(m~*+ C_A)ζ的变化规律, 给出了预测A*_(max) 值的拟合公式, 采用该模型计算了三维柔性结构在均匀来流和简谐波形来流作用下的VIV响应.结构在均匀来流作用下振动呈现由驻波向行波的变化过程, 并最后稳定为行波振动形态, 在简谐波形来流作用下, 结构呈现混合振动形态, 幅值随时间呈周期变化

Metallic glass nanofilms

In this paper, we report for the first time the spontaneous formation of Zr-based metallic glass nanofilms by developed dynamic forced-shear-rupture technique of hat-shaped specimens. The obtained nanofilms have about 100 nm thickness and other two geometrical dimensions can reach micrometer scales. Their glassy nature and structural stability were solidly identified. It was found that electrons with the wavelength of less than 0.165 Å could make the metallic glass nanofilms transparent. Furthermore, it is clearly shown that shearbanding instability still afflicts such 100-nm-thick metallic glass nanofilms.

Xe~(23+)离子辐照Al_2O_3的光谱特性

本工作研究460 keV、3 MeV和308 MeV Xe23+辐照Al2O3单晶样品的光致发光特性。从经过460 keV Xe23+辐照后样品的光致发光测试结果可看到,波长为380、413和450 nm的发光峰明显增强,在390和564 nm处出现了新的发光峰。从3 MeV的Xe23+辐照后样品谱的变化可看到,在较低剂量条件下,516 nm(2.4 eV)和564 nm(2.2 eV)处的发光峰随辐照剂量增加而增强,且当剂量增到1×1016cm-2时,564 nm处的发光峰消失,只有516 nm(2.4 eV)处的发光峰较强。从308 MeV Xe23+辐照后样品的光致发光谱中可看到,357 nm(3.47 eV)和516 nm(2.4 eV)处的发光峰随着剂量增加明显增强。辐照后样品的FTIR谱显示:波数在460~510 cm-1和630 cm-1附近的吸收是Al2O3振动模式,经离子辐照后,吸收带展宽;1 000~1 300 cm-1间为Al—O—Al桥氧键的伸缩振动模式,高能辐照后的吸收带向低波数方向移动。

基于RS-485总线和MCU的频率合成器设计

本文主要介绍一款基于RS-485总线和MCU的频率合成器,重点介绍了频率合成器的总体结构,RS-485总线接口电路,高集成度频率合成芯片AD9850的外围硬件电路和控制软件。该合成器输出频率范围:5~40MHz,最小频率步进为≤20Hz,输出正弦波或方波幅度800mV。该频率合成器具有结构简单,精度高,控制灵活的特点。

~(139)Ce的多准粒子激发态

利用能量为50MeV的12C束流,通过反应130Te(12C,3n)布居了139Ce的高自旋态．基于标准在束核谱学实验测量结果,扩展并更新了139Ce的能级纲图．139Ce的能级结构具有球形原子核的典型特征,其高自旋态由单粒子激发形成．利用经验壳模型计算了139Ce的多准粒子激发态能量,研究了其高自旋激发态的多准粒子特性．

黄土高原南部全新世黄土-古土壤序列若干元素分布特征及意义

IEECAS SKLLQG

Study of multi-quasiparticle excited states in Ce-139

High-spin states in Ce-139 have been populated using the Te-130(C-12, 3n) reaction at beam energy of 50MeV. The level scheme of Ce-139 has been revised and extended greatly up to E=5765.0keV. The level structure of Ce-139 shows typical characteristics of spherical nucleus, and the high-spin states were formed by the excitations of valence nucleons. Energies of the yrast and near yrast high-spin states in Ce-139 have been calculated by the empirical shell model, and the multi-quasiparticle nature of high-spin excited states has been discussed.

低速~(40)Ar~(17+)离子入射金属Be表面发射的近红外光谱线和X射线谱；Infrared Light and X-ray Emissions of ~(40)Ar~(17+) Impacting on Be Surface ；

用速度不同的(动能EK=272和357keV,速度v=1.14×106和1.72×106m/s)的高电荷态离子40Ar17+分别入射金属Be表面,同时测量这种相互作用过程中产生的近红外光谱线和X射线谱。实验结果表明,在低速范围内(速度小于玻尔速度vBohr=2.19×106m/s),速度较小的40Ar17+离子在到达金属的表面临界距离Rc到进入表面(2—3原子层)的进程中,形成了较多的高激发态Ar原子,其退激辐射较强的光谱线,进而验证了经典过垒模型。