用自适应脉冲微扰引导混沌系统到周期解

用自适应脉冲微扰方法控制的系统的某个系统变量作为驱动,设计了一种自适应控制器方法对两个或多个响应混沌系统进行脉冲微扰,引导这些系统从混沌运动到低周期运动,实现同时控制多个混沌系统到不同的周期态. 当选择相同的自适应控制器输入变量实施脉冲微扰时,还可控制两个或多个混沌系统达到不同的周期态同步. 通过对R?ssler混沌系统的仿真研究证实了方法的有效性. 关键词： 混沌控制 系统参量 自适应控制器 脉冲微扰 周期态同步     

三硝基苯磺酸离子选择电极的制备和应用

三硝基苯磺酸是氨基酸分析常用试剂,在水溶液中它是稳定的一价阴离子。Sarantonis曾研制液膜型三硝基苯磺酸离子选择电极,间接测定氨基酸的浓度,其电极的线性响应范围为1.1×10~(-1)～5.1×10~(-5)mol·L~(-1)。     

新型三唑类抗真菌化合物的三维定量构效关系研究

采用比较分子力场分析法(CoMFA)和比较分子相似性指数分析法(CoMSIA), 系统研究了40个新型三唑类化合物抗真菌活性的三维定量构效关系. 在CoMFA研究中, 研究了两种药效构象对模型的影响, 并考察了网格点步长对统计结果的影响. 在CoMSIA研究中, 系统考察了各种分子场组合、网格点步长和衰减因子对模型统计结果的影响, 发现立体场、静电场、疏水场和氢键受体场的组合得到最佳模型. 所建立CoMFA和CoMSIA模型的交叉相关系数q²值分别为0.718和0.655, 并都具有较强的预测能力. CoMFA和CoMSIA模型的三维等值线图直观地解释了化合物的构效关系, 阐明了化合物结构中苯环上各位置取代基对抗真菌活性的影响, 为进一步结构优化提供了重要依据.     

单向耦合下两个不同Lorenz系统的广义同步

对单向耦合下两个不同的Lorenz系统的广义同步进行了研究,利用辅助系统方法,基于稳定性理论和响应系统的有界性,得到了它们达到广义同步时的充分条件,并根据响应系统的修正系统具有零渐近稳定平衡点、非零渐近稳定平衡点和轨道渐近稳定周期解的情况,将广义同步分为第一类、第二类和第三类;利用Routh-Hurwitz定理,对修正系统平衡点的稳定性进行了分析,给出了单向耦合下两个不同Lorenz系统具有第一类、第二类广义同步的充分条件.数值仿真表明了该方法的有效性与可行性.     

Generalized spatiotemporal chaos synchronization of the Ginzburg-Landau equation

In this paper, the generalized synchronization of two unidirectionally coupled Ginzburg-Landau equations is studied theoretically. It is demonstrated that the drive-response system has bounded attraction domain and compact attractors. It is derived that the correction equation has asymptotically stable zero solutions under certain conditions and that the sufficient conditions for smooth generalized synchronization and Hölder continuous generalized synchronization exist in the coupling system. Numerical result analysis shows the correctness of theory.     

空心六边形镍钴硫化物/RGO复合物的合成及其超级电容性能

通过两步法制备了一种空心六边形镍钴硫化物(HHNCS)与还原氧化石墨烯(RGO)的纳米复合材料HHNCS/RGO。利用XRD,SEM,TEM和Raman光谱等对复合物进行表征,发现镍钴硫化物为空心六边形结构,并且均匀地附着在RGO的表面。该纳米复合物用作超级电容器电极表现出优异的电化学性能。在电流密度为1 A·g-1时比电容为927 F·g-1;当电流密度增大到20 A·g-1时,比电容仍高达724 F·g-1,表明材料拥有较好的倍率性能。此外,在电流密度5 A·g-1下循环2 000次后比电容保留有初始值的93%,显示出优异的循环稳定性。HHNCS/RGO优异的电容性能主要是由于RGO的存在不仅增强了材料的导电性,而且作为理想的载体分散HHNCS纳米片。HHNCS/RGO纳米复合物优异的电化学性能使其在超级电容器电极材料领域具有应用前景。     

Effects of the curvature radius of a cylindrical shell on the stress intensity factors of surface cracks

The effects of the curvature radius of a cylindrical shell on stress intensity factors are investigated in circumferential (inner and outer) semielliptical surface cracks in a cylindrical shell. What is new in this paper is to have given: (1) The stress intensity factors for surface cracks in a cylindircal shell are determined by photoelastic technique. (2) By a special method photoelastic slices are handled for obtaining a clear caustic curve, and the stress intensity factors for surface cracks in a cylindrical shell are determined by the caustic method. (3) An approximate equation of curvature correction factor F_c is proposed. (4) Effects of the curvature radius R of a cylindrical shell on the stress intensity factors of surface cracks are obtained. The results of this paper are in fair agreement with already existing analytical results. The approximate equation of curvature correction factor F_c can be widely used for engineering purposes.     

关于非线性系统两类广义混沌同步存在性的研究

研究了非线性系统两类广义混沌同步的存在性.即在响应系统的修正方程在具有渐近稳定平衡点或渐近稳定周期轨道的情况下,满足一定的条件,可将广义同步化流形存在性问题转化为Lipschitz函数族的压缩不动点问题,理论上严格证明了该广义同步化流形的指数吸引性.数值仿真证实了理论的正确性及有效性. 关键词： 广义同步化流形 压缩不动点 指数吸引性     

Amino acid derivatives of pyropheophorbide-α ethers as photosensitizer: Synthesis and photodynamic activity

Ten new water-soluble amino acid conjugates of pyropheophorbide-α ethers 4a-4j were synthesized and investigated for their in vitro photodynamic antitumor activity. The results showed that all compounds exhibited higher phototoxicity and lower dark toxicity against three kinds of tumor cell lines than BPD-MA. In particular, themost phototoxic compound 4d and 4j individually showed IC₅₀ values of 41 nmol/L and 33 nmol/L against HCT116 cell, which represented 7.8- and 9.7-fold increase of antitumor potency compared to BPD-MA, respectively, suggesting that they were promising photosensitizers for PDT applications because of their strong absorption at long wavelength (λ_max>650 nm), high phototoxicity, low dark cytotoxicity and good water-solubility.     

关于非自治系统三类广义同步存在性的研究

研究了两个单向耦合的非自治系统三类广义同步的存在性.在响应系统的修正方程具有渐近稳定平衡点、渐近稳定周期轨道或渐近稳定拟周期轨道的情况下,满足一定的条件,可将广义同步化流形存在性问题转化为Lipschitz函数族的压缩不动点问题,并且理论证明了该广义同步化流形的指数吸引性.同时,以Duffing系统为例进行了数值仿真,其结果与理论推导相一致. 关键词： 广义同步化流形 压缩不动点 指数吸引性