Low-temperature phase formation in the SrF2–LaF3 system

Phase formation in the SrF₂–LaF₃ system was studied at temperatures ranging from 300°C to 450°C using nitrate flux. The solubility of LaF₃ in SrF₂ decreases with decreasing temperature. The equilibrium width of the solid solution region Sr_1−xLa_xF_2+x at 400°C, it is 44.6 ± 0.4 mol% LaF₃ (x = 0.446), at 350°C — 38.3 ± 0.7 mol% LaF₃ (x = 0.383), and decreases almost to zero at 300°C.     

同步数据流语言高阶运算消去的可信翻译

Lustre是一种广泛应用于工业界核心安全级控制系统的同步数据流语言,采用形式化验证的方法实现Lustre到C的编译器可以有效地提高编译器的可信度.基于这种方法,开展了从Lustre*(一种类Lustre语言)到C子集Clight的可信编译器的研究.由于Lustre*与Clight之间巨大的语言差异,整个编译过程划分为多个层次,每个层次完成特定的翻译工作.阐述了其中高阶运算消去的翻译算法,翻译过程采用辅助定理证明工具Coq实现,并进行严格的正确性证明.     

具有属性析取扩展特征的内逆P-信息智能挖掘

逆P-集合(inverse packet sets)是由内逆P-集合P-F(internal inverse packet set(X)F)与外逆P-集合XF(outerinverse packet setXF)构成的集合对;或者,((X)F,(X)F)是逆P-集合;逆P-集合具有动态特性.它是研究另一类动态信息与应用的新模型.逆P-集合中元素的属性满足属性析取.利用内逆P-集合的结构,给出了元素的属性析取扩展形式与特征、属性析取扩展条件下的内逆P-信息智能挖掘,以及挖掘定理与智能挖掘原理;给出了满足内逆P-推理与非完整信息条件下的完整信息的智能挖掘-发现.利用这些结果,给出了具有属性析取扩展特征的信息智能挖掘的应用.     

随机背包公钥密码的分析与改进

针对随机背包公钥密码方案,提出一种私钥恢复攻击方法.发现Wang等人所构造的随机背包公钥方案实际上是隐含使用了一个特殊的超递增背包.通过使用普通超递增背包代替该特殊超递增背包,将超递增背包隐藏在随机选择的背包中,对原方案进行了改进,提出一种新的基于中国剩余定理的背包公钥密码方案.改进后的方案消除了原方案存在的设计缺陷,能够抵抗针对原方案提出的格规约攻击、低密度攻击以及shamir攻击.     

基于网络编码的无线网络容量分析

无线网络容量一直是无线网络领域的研究热点,而网络编码通过赋予中间节点对接收数据包进行编码、组合的能力,可以有效提高网络容量,达到最大流—最小割定理确定的理论上限.本文在Gupta和Kumar提出的信号干扰噪声比模型基础上,首先分析网络节点均匀分布时发送节点与目的节点进行多跳传输的无线网络容量计算方法;接着推导出了基于网络编码的无线网络容量计算公式,并利用MATLAB中求解线性规划问题的函数linprog()求解网络最大流及各链路流量,以此求出无线网络容量上界.通过对无线网络容量上界进行MATLAB仿真,得到如下结论:无线网络容量上界随节点数量的增加呈现先增加后减少的趋势;且当节点数量趋于无穷大时,网络容量趋于零;与传统的存储转发模式相比,采用网络编码有利于提高网络容量.     

Input‐output triggered control using ‐stability over finite horizons

This paper investigates stability of nonlinear control systems under intermittent information. Following recent results in the literature, we replace the traditional periodic paradigm, where the up‐to‐date information is transmitted and control laws are executed in a periodic fashion, with the event‐triggered paradigm. Building on the small gain theorem, we develop input–output triggered control algorithms yielding stable closed‐loop systems. In other words, based on the currently available (but outdated) measurements of the outputs and external inputs of a plant, a mechanism triggering when to obtain new measurements and update the control inputs is provided. Depending on the noise in the environment, the developed algorithm yields stable, asymptotically stable, and ‐stable (with bias) closed‐loop systems. Control loops are modeled as interconnections of hybrid systems for which novel results on ‐stability are presented. The prediction of a triggering event is achieved by employing ‐gains over a finite horizon. By resorting to convex programming, a method to compute ‐gains over a finite horizon is devised. Finally, our approach is successfully applied to a trajectory tracking problem for unicycles. Copyright © 2014 John Wiley & Sons, Ltd.     

On the Controllability of Nonlocal Second‐Order Impulsive Neutral Stochastic Integro‐Differential Equations with Infinite Delay

In this paper, we investigate the controllability for a class of nonlocal second‐order impulsive neutral stochastic integro‐differential equations with infinite delay in Hilbert spaces. More precisely, a set of sufficient conditions for the controllability results of nonlocal second‐order impulsive neutral stochastic integro‐differential equations with infinite delay are derived by means of the Banach fixed point theorem combined with theories of a strongly continuous cosine family of bounded linear operators. As an application, an example is provided to illustrate the obtained theory.     

新型指令滤波反步及高超声速飞行器的应用

非线性严反馈系统的控制中,由于迭代和系统的设计过程,反步法成为研究热点之一。然而,由于需要推导虚拟控制的解析导数,传统反步法存在"计算膨胀"问题,当被控对象的系统阶数较高或模型较复杂时,"计算膨胀"问题更为严重,这限制了反步法在实际工程中的应用。因此,提出一类新型的指令滤波反步法,避免传统反步法中"计算膨胀"问题。该方法采用输入状态稳定性(Input-to-State Stability,ISS)和小增益定理保证闭环系统的稳定性,为严反馈系统的控制器设计提供了简洁有效的方式。针对高超声速飞行器巡航段纵向的速度和高度跟踪问题,综合指令滤波反步法和动态逆方法设计有效的状态反馈控制器,最后在数值仿真中验证了所设计的控制器能实现高超声速飞行器在爬升机动中对速度和高度的稳定跟踪。     

A comment on the “Robust stability analysis of fractional order interval polynomials”, by Nusret Tan et al.

It is shown that Theorem 3 in the article mentioned in the title is not true and some modification is suggested to eliminate the mistake.     

Complete controllability for abstract measure differential systems

In this paper, we investigate the complete controllability for abstract measure differential systems. Firstly, we introduce several new concepts about complete controllability for abstract measure differential systems. Then, on the basis of the Sadovskii fixed‐point theorem, we give sufficient conditions for complete controllability for a class of abstract measure differential systems. The compactness of the semigroup generated by some operator is unnecessary in this paper, and we show that our results, dealing with complete controllability problem for an ordinary differential system in infinite‐dimensional Banach space, are also less conservative than that in the previous literature. Copyright © 2012 John Wiley & Sons, Ltd.