An image encryption scheme based on time-delay and hyperchaotic system

In this paper, a novel image encryption scheme based on time-delay and hyperchaotic system is suggested. The time-delay phenomenon is commonly observed in daily life and is incorporated in the generation of pseudo-random chaotic sequences. To further increase the degree of randomness, the output of the hyperchaotic system is processed before appending to the generated sequence. A novel permutation function for shuffling the position index, together with the double diffusion operations in both forward and reverse directions, is employed to enhance the encryption performance. Experimental results and security analyses show that the proposed scheme has a large key space and can resist known-plaintext and chosen-plaintext attacks. Moreover, the encryption scheme can be easily modified to adopt other hyperchaotic systems under the same structure.     

激光驱动复合飞片冲击起爆HNS-Ⅳ实验研究

激光驱动飞片冲击起爆技术具有很强的抗电磁干扰能力和可以直接起爆钝感炸药等优点,能够满足现代战场对火工系统的高安全性和高可靠性要求。HNS-Ⅳ是最适合激光驱动飞片冲击起爆技术的药剂。本文中在6种不同激光能量下,测试了Al/Al₂O₃/Al复合飞片和Al单层飞片对HNS-Ⅳ药剂(装药密度为1.5 g/cm3)的冲击起爆情况。实验实现了激光驱动飞片对HNS-Ⅳ的成功起爆。在217~245 mJ激光能量范围内,激光驱动Al/Al₂O₃/Al复合飞片均可成功完全起爆HNS-Ⅳ药柱。Al单层飞片均未成功起爆HNS-Ⅳ药柱。飞片冲击压力对激光驱动飞片冲击起爆HNS-Ⅳ起决定作用。     

涉及极点重级与分担值的亚纯函数正规定则

运用分担值的思想证明了涉及极点重数的亚纯函数族的正规定则,所得结论推广了相关文献的主要结果.     

On the existence of positive least energy solutions for a coupled Schrödinger system with critical exponent

In this paper, we consider the following coupled Schrödinger system with critical exponent: where is a smooth bounded domain, λ > 0,μ≥0, and . Under certain conditions on λ and μ, we show that this problem has at least one positive least energy solution. Copyright © 2016 John Wiley & Sons, Ltd.     

Moduli spaces of arrangements of 10 projective lines with quadruple points

We classify moduli spaces of arrangements of 10 lines with quadruple points. We show that moduli spaces of arrangements of 10 lines with quadruple points may consist of more than 2 disconnected components, namely 3 or 4 distinct points. We also present defining equations to those arrangements whose moduli spaces are still reducible after taking quotients of complex conjugations.     

Nonlinear vibration analysis of double-walled carbon nanotubes based on nonlocal elasticity theory

The nonlinear free vibration of double-walled carbon nanotubes based on the nonlocal elasticity theory is studied in this paper. The nonlinear equations of motion of the double-walled carbon nanotubes are derived by using Euler beam theory and Hamilton principle, with considering the von Kármán type geometric nonlinearity and the nonlinear van der Waals forces. The surrounding elastic medium is formulated as the Winkler model. The harmonic balance method and Davidon–Fletcher–Powell method are utilized for the analysis and simulation of the nonlinear vibration. The simulation results show that the nonlocal parameter, aspect ratio and surrounding elastic medium play more important roles in the nonlinear noncoaxial vibration than those in the coaxial vibration of the double-walled carbon nanotubes. The noncoaxial vibration amplitudes of only considering nonlinear van der Waals forces are larger than those of considering both geometric nonlinearity and nonlinear van der Waals forces.     

A Kuznetsov Formula for Kloosterman Sums on GLn

We prove a Kuznetsov sum formula for Kloosterman sums on GL _n corresponding to the big Bruhat cell. Using this formula, a weighted sum of Kloosterman sums can be expressed in spectral decomposition. A non-trivial estimate of the spectral side might lead to a proof of cancellations in sums of Kloosterman sums on GL _n.     

具有色多项式∑n＋2／k[k n＋2—k]（λ）k＋1的图

本文讨论了色项式为∑/k≤n 2(n 2)/k[k n 2-k](λ）k 1的图的结构,给出了具有这种色多项式的全部色等价图。     

A Polynomial Time Approximation Scheme for Optimal Product-Requirement Communication Spanning Trees

Given an undirected graph with nonnegative edge lengths and nonnegative vertex weights, the routing requirement of a pair of vertices is assumed to be the product of their weights. The routing cost for a pair of vertices on a given spanning tree is defined as the length of the path between them multiplied by their routing requirement. The optimal product-requirement communication spanning tree is the spanning tree with minimum total routing cost summed over all pairs of vertices. This problem arises in network design and computational biology. For the special case that all vertex weights are identical, it has been shown that the problem is NP-hard and that there is a polynomial time approximation scheme for it. In this paper we show that the generalized problem also admits a polynomial time approximation scheme.