Protein Adsorption Switch Constructed by a Pillar[5]arene‐Based Host–Guest Interaction

The interfacial properties of solid substrates are of importance for protein adsorption. Herein, we report a reversible protein adsorption switch based on the host–guest interaction of the butoxy pillar[5]arene and adipic acid. By the detector of the contact angle (CA), atomic force microscopy (AFM), and luminoscope on the silicon substrate, the intelligent protein switch exhibits excellent adsorptivity for BSA and switch performance by pH regulation.     

A four-wing chaotic attractor generated from a new 3-D quadratic autonomous system

This paper introduces a new 3-D quadratic autonomous system, which can generate two coexisting single-wing chaotic attractors and a pair of diagonal double-wing chaotic attractors. More importantly, the system can generate a four-wing chaotic attractor with very complicated topological structures over a large range of parameters. Some basic dynamical behaviors and the compound structure of the new 3-D system are investigated. Detailed bifurcation analysis illustrates the evolution processes of the system among two coexisting sinks, two coexisting periodic orbits, two coexisting single-wing chaotic attractors, major and minor diagonal double-wing chaotic attractors, and a four-wing chaotic attractor. Poincaré-map analysis shows that the system has extremely rich dynamics. The physical existence of the four-wing chaotic attractor is verified by an electronic circuit. Finally, spectral analysis shows that the system has an extremely broad frequency bandwidth, which is very desirable for engineering applications such as secure communications.     

Hyperchaotic attractors from a linearly controlled Lorenz system

In this paper, a four-dimensional (4D) continuous-time autonomous hyperchaotic system with only one equilibrium is introduced and analyzed. This hyperchaotic system is constructed by adding a linear controller to the second equation of the 3D Lorenz system. Some complex dynamical behaviors of the hyperchaotic system are investigated, revealing many interesting properties: (i) existence of periodic orbit with two zero Lyapunov exponents; (ii) existence of chaotic orbit with two zero Lyapunov exponents; (iii) chaos depending on initial value $w_0$; (iv) chaos with only one equilibrium; and (v) hyperchaos with only one equilibrium. Finally, two complete mathematical characterizations for 4D Hopf bifurcation are derived and studied.     

Estimating the ultimate bound and positively invariant set for the Lorenz system and a unified chaotic system

To estimate the ultimate bound and positively invariant set for a dynamic system is an important but quite challenging task in general. In this paper, we attempt to investigate the ultimate bound and positively invariant set for two specific systems, the Lorenz system and a unified chaotic system. We derive an ellipsoidal estimate of the ultimate bound and positively invariant set for the Lorenz system, for all the positive values of its parameters a, b and c, and obtain the minimum value of volume for the ellipsoid. Comparing with the best results in the current literature [D. Li, J. Lu, X. Wu, G. Chen, Estimating the bounds for the Lorenz family of chaotic systems, Chaos Solitons Fractals 23 (2005) 529-534; X. Liao, On the global basin of attraction and positively invariant set for the Lorenz chaotic system and its application in chaos control and synchronization, Sci. China Ser. E 34 (2004) 1404-1419], our new results fill up the gap of the estimate for the cases of 0<a<1 and 0<b<2 [X. Liao, On the global basin of attraction and positively invariant set for the Lorenz chaotic system and its application in chaos control and synchronization, Sci. China Ser. E 34 (2004) 1404-1419]. Furthermore, the estimation derived here contains the results given in [D. Li, J. Lu, X. Wu, G. Chen, Estimating the bounds for the Lorenz family of chaotic systems, Chaos Solitons Fractals 23 (2005) 529-534] and [X. Liao, On the global basin of attraction and positively invariant set for the Lorenz chaotic system and its application in chaos control and synchronization, Sci. China Ser. E 34 (2004) 1404-1419] as special cases. Along the same line, we also provide estimates of cylindrical and ellipsoidal bounds for a unified chaotic system, for its parameter range , and obtain the minimum value of volume for the ellipsoid. The estimate is more accurate than and also extends the result of [D. Li, J. Lu, X. Wu, G. Chen, Estimating the bounds for the Lorenz family of chaotic systems, Chaos Solitons Fractals 23 (2005) 529-534] and [X. Liao, On the global basin of attraction and positively invariant set for the Lorenz chaotic system and its application in chaos control and synchronization, Sci. China Ser. E 34 (2004) 1404-1419].     

4-氟-3-羟基-1-取代苯基-6-哒嗪酮及其衍生物的合成

报导4-氟-3-羟基-1-取代苯基-6-哒嗪酮及其衍生物的合成,氟代顺丁烯二酸酐和取代苯肼类反应的研究结果及部分化合物的药理实验结果。     

关于Kalman的标准系统分解

本文给出一个反例,指出Kalman关于他本人提出的标准系统分解的原始证明以及后来孙承启先生在《自动化学报》1984年第3期上发表的证明均是错误的。事实上,如何严格地证明(或反证)这一重要结论尚是一个未有彻底解决的问题。     

近最优轨道线性数字滤波器

为了克服Kalman最优线性滤波计算过于复杂的缺点,本文引进“近最优滤波”作为定常离散时间系统中大样本数据过程的一种极限处理,通过使用极限式Kalman增益矩阵,获得一种结构简单使用方便的极限式Kalman最优线性滤波。本文用扩大维数的办法讨论一般的有色噪声过程而把白噪声过程作为特殊情况导出。在近最优α-β-γ轨道滤波器中,我们可以通过对参数的适当选择而克服误差协方差矩阵退化的现象并且由于整个滤波器的结构简单而不致于增大计算量,从而为有色噪声数据过程的线性滤波提供一种可行的途径。在本文中,对有色噪声情形我     

Breaking a chaos-noise-based secure communication scheme

This paper studies the security of a secure communication scheme based on two discrete-time intermittently chaotic systems synchronized via a common random driving signal. Some security defects of the scheme are revealed: 1) The key space can be remarkably reduced; 2) the decryption is insensitive to the mismatch of the secret key; 3) the key-generation process is insecure against known/chosen-plaintext attacks. The first two defects mean that the scheme is not secure enough against brute-force attacks, and the third one means that an attacker can easily break the cryptosystem by approximately estimating the secret key once he has a chance to access a fragment of the generated keystream. Yet it remains to be clarified if intermittent chaos could be used for designing secure chaotic cryptosystems.     

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为了更好地发挥<力学进展>对力学研究的促进作用,编委会决定,选择有发展前景的若干力学研究方向组织专辑评述:即,每次围绕一个方向约请若干国内外知名专家从不同的角度撰写综述评论文章,集中于一期内发表,并提供较详细的重要参考文献,以便向读者展示该方向最新发展的全貌,从而达到开阔学术思想、启发探索兴趣、提供研究导向的目的.     

Suppressing chaos in fractional-order systems by periodic perturbations on system variables

Based on extensive numerical and computer-graphical simulations, it is shown that fractional-order chaotic systems can be stabilized by slightly perturbing the system state variables periodically. In this chaos control scheme, the tunable parameters are chosen empirically. The effectiveness of this chaos control method is demonstrated by fractional-order Lorenz, Chen and Rössler systems, where the underlying initial value problems are numerically integrated by using the Grünwald-Letnikov method.