The study on the chaotic motion of a nonlinear dynamic system

ｎｔｒｏｄｕｃｔｉｏｎＩｎｒｅｃｅｎｔｙｅａｒｓ,ｃｈａｏｓｉｎｎｏｎｌｉｎｅａｒｄｙｎａｍｉｃｓｙｓｔｅｍｓｈａｓｂｅｎａｒｏｕｓｉｎｇｍｏｒｅａｎｄｍｏｒｅｉｎｔｅｒｅｓｔ［１～３］．Ｔｈｅｃｈａｏｔｉｃｍｏｔｉｏｎｉｓｒｅｇａｒｄｅｄａｓａｎａ...     

The asymptotic solution of a dynamic buckling problem in elastic columns

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｔｒａｉｇｈｔｃｏｌｕｍｎｉｓａｋｉｎｄｏｆｓｔｒｕｃｔｕｒａｌｃｏｍｐｏｎｅｎｔｓｏｆｔｅｎｕｓｅｄｉｎｅｎｇｉｎｅｒｉｎｇ,ｉｔｓｄｙｎａｍｉｃｂｕｃｋｌｉｎｇｈａｓｂｅｎｐａｉｄｍｕｃｈａｔｅｎｔｉｏｎｔｏｆｏｒ...     

The double mode model of the chaotic motion for a large deflection plate

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｌａｓｔｄｅｃａｄｅｈａｓｗｉｔｎｅｓｅｄｔｈｅｉｎｃｒｅａｓｉｎｇａｄｖａｎｃｅｓｉｎｔｈｅｓｔｕｄｙｏｆｃｈａｏｔｉｃｖｉｂｒａｔｉｏｎｏｆｍｅｃｈａｎｉｃａｌｓｙｓｔｅｍｓ．Ｈｏｗｅｖｅｒ,ｇｒｅａｔａｔｅｎｔｉｏ...     

如何计算太阳的寿命

 天体物理学的理论认为,恒星的演化过程可分为如下几个阶段：恒星的诞生（引力收缩阶段）,主序星阶段,红巨星阶段和红巨星以后的演化阶段．现有恒星的９０％以上都正处在主序星阶段,我们的太阳就是一颗主序星．主序星是壮年时期的恒星,在它内部进行着氢聚变为氦的热核反应,反应释放的热能正好和恒星向外部空间的辐射相平衡,因此恒星的温度基本维持不变,此时恒星由于自吸引而收缩的作用和恒星内部的压力相平衡,所以恒星的体积也基本不变,这是恒星一生中最为稳定的时期,也是生命史上历时最长的时期．太阳的寿命理应指它从诞生到死亡的时间长度,一则因为它在主序星阶段时间最长,更重要的是,当它从主序星过渡到红巨星时.     

弹性直杆中一类动力屈曲问题的渐近解

对于弹性杆受刚性块轴向撞击的动力屈曲问题而言,由于轴向载荷形式较为复杂,问题将归结为关于非线性偏微分方程组解的讨论,至今仍未能得到一个理论上的解析解,为此,讨论了有限长理想弹性直杆的此类动力屈曲问题,采用小参数的摄动展开和变分法,成功地得到了这一问题的一个理论上的近似解,并给出了相应的算例,从中得到了一些有益的结论.     

分子络合物的键能研究

本文提出一个定量表达分子络合物中给体和受体作用能的计算模式.根据此模式对约350种分子络合物的生成热进行计算,计算值和实验值吻合良好.在此键能计算模式的基础上,还对给体电离势、配位中心和位阻效应等问题展开讨论.     

The propagation of solitary waves in a nonlinear elastic rod

In this paper, the inverse scattering method is used to analyse strain sohtarv waves bed nonlinear clastic rod. Properties of solitary waves and their influence on solid structures are discussed in detail. Some quantitative results are given.     

The TSHB technique for material testing at high rates of strain

The material testing technique of Torsional Split Hopkinson Bar (TSHB) is investigated in this paper. It can solve nearly all the problems of Split Hopkinson Pressure Bar (SHPB). Furthermore, accurate experimental results can be obtained in large deformation condition. In this paper some dynamic stress-strain curves of some engineering materials are also given which are obtained from a TSHB apparatus made by ourselves.Projects Supported by the Science Fund of the Chinese Academia Sinica.     

Laser-Chirp Controlled Terahertz Wave Generation from Air Plasma

We report the laser-chirp controlled terahertz(THz) wave generation from two-color-laser-induced air plasma.Our experimental results reveal that the THz wave is affected by both the laser energy and chirp,leading to radiation minima that can be quantitatively reconstructed using the linear-dipole-array model.The phase difference between the two colors,determined by the chirp and intensity of the laser,can account for the radiation minima.Furthermore,we observe an asynchronous variation in the ge...     

共价有机骨架材料修饰碳糊电极电化学检测铜离子

利用溶剂热反应合成共价有机骨架材料TpBD-COF，通过扫描电子显微镜和红外光谱表征其形貌和结构。按照一定比例将石墨粉、 TpBD-COF、离子液体(BPPF6)和石蜡油混合研磨，制备COF-2-BPPF6-CPE碳糊电极，采用循环伏安法(CV)和差分脉冲伏安法(DPV)评估修饰电极的电化学性能。在pH 3.50的邻苯二甲酸氢钾缓冲溶液中，Cu²⁺在修饰电极上有灵敏的电流响应。COF修饰碳糊电极对Cu²⁺有更高的峰电流，且峰电流与Cu²⁺浓度在1～200μmol/L呈线性关系(R2=0.9997)，检出限为0.13μmol/L。利用该修饰电极，采用标准加入法对水样中的Cu²⁺进行测定，回收率为100.6%～101.2%，表明其可用于检测水体中的Cu²⁺。