变长码的抗误码扩散能力分析

给出了一种基于离散无记忆信源模型的分析变长码抗误码扩散能力.该方法通过分析序列中某一时刻某个码字出现的概率,以及该码字发生错误后正好变成与该码字同码长的另一码字的概率,得到该时刻不发生误码扩散的概率.而整个序列不发生误码的概率为该概率的序列长次幂.模拟计算结果显示,该方法可在不增加平均码长和码方差的情况下,选择出抗误码扩散能力最好的码组.     

具有高阶代数免疫的弹性函数

构造了一类具有一阶弹性的函数.该函数是级联4个具有一对拟线性变量的子函数得到的.给出了新函数代数次数不增加的充分必要条件,代数免疫阶不增加的必要条件.选取的初始函数不满足代数次数和代数免疫不增加的必要条件,那么得到函数和初始函数相比,代数免疫至少增加1阶,代数次数增加1次,并且具有1阶弹性.     

k-Edge Failure Resilient Network Design

We design a network that supports a feasible multicommodity flow even after the failures of any k edges. We present a mixed-integer linear program (MILP), a cutting plane algorithm, and a column-and-cut algorithm. The algorithms add constraints to repair vulnerabilities in partial network designs. Empirical studies on previously unsolved instances of SNDlib demonstrate their effectiveness.     

Numerical recovery strategies for parallel resilient Krylov linear solvers

As the computational power of high‐performance computing systems continues to increase by using a huge number of cores or specialized processing units, high‐performance computing applications are increasingly prone to faults. In this paper, we present a new class of numerical fault tolerance algorithms to cope with node crashes in parallel distributed environments. This new resilient scheme is designed at application level and does not require extra resources, that is, computational unit or computing time, when no fault occurs. In the framework of iterative methods for the solution of sparse linear systems, we present numerical algorithms to extract relevant information from available data after a fault, assuming a separate mechanism ensures the fault detection. After data extraction, a well‐chosen part of missing data is regenerated through interpolation strategies to constitute meaningful inputs to restart the iterative scheme. We have developed these methods, referred to as interpolation–restart techniques, for Krylov subspace linear solvers. After a fault, lost entries of the current iterate computed by the solver are interpolated to define a new initial guess to restart the Krylov method. A well‐suited initial guess is computed by using the entries of the faulty iterate available on surviving nodes. We present two interpolation policies that preserve key numerical properties of well‐known linear solvers, namely, the monotonic decrease of the A‐norm of the error of the conjugate gradient or the residual norm decrease of generalized minimal residual algorithm for solving. The qualitative numerical behavior of the resulting scheme has been validated with sequential simulations, when the number of faults and the amount of data losses are varied. Finally, the computational costs associated with the recovery mechanism have been evaluated through parallel experiments. Copyright © 2016 John Wiley & Sons, Ltd.     

具有高非线性度和最优代数次数的弹性函数的构造

具有良好的非线性度和最优代数次数的弹性布尔函数在流密码和分组密码设计和分析中起着至关重要的作用.本文通过修改Maiorana-McFarland(M-M)类Bent函数,利用不同的低阶弹性函数,给出构造高非线性度弹性布尔函数的一种新方法,所构造的函数具有严格几乎最优的非线性度和最优的代数次数.     

Fabrication of Polypropylene (PP)/Poly Trimethylene Terephthalate (PTT)/Nanoclay Nanocomposite Fibers with Tailored Properties

Abstract

The main aim of this study was to deal with one of the major drawbacks of polypropylene (PP) fibers, i.e., low resiliency and low dyeability, by incorporating polytrimethylene terephthalate (PTT) fibrils, as a dispersed material, and organoclay, as a nano-filler, into the PP polymer matrix. The presence of 10?wt% of PTT and 0.5–1?wt% organoclay in the PP nanocomposite fibers led to an approximately 18.5% and 45.5% increase in the resilience behavior and dye uptake, respectively, compared to pure PP fibers, without using highly toxic carriers. The lowest mean diameter of the nano-fibrils was 75?nm for the hot drawn nanocomposite fiber samples as measured by scanning electron microscopy (SEM). The results of DSC indicated that the presence of both PTT and organoclay significantly influenced the crystallinity of the PP which also confirmed their nucleating effects in the nanocomposite fiber.     

一阶弹性函数次数的最优化

研究了S.Maitra提出的一阶弹性函数进行次数最优化的一种方法.对次数优化过程中非线性度的影响进行分析,给出了决定非线性度变化相应的判定定理,在对函数进行次数最优化的同时,使得非线性度增加4或者保持不变.     

Fabrication of Polypropylene/Poly (Trimethylene Terephthalate) Blend Fibers with Highly Improved Resiliency and Preserved Mechanical Properties

The main aim of this study was to deal with one of the major drawbacks of polypropylene (PP) fibers, i.e. low resiliency, by incorporating poly (trimethylene terephthalate) (PTT) nano-fibrils as a dispersed material into the PP polymer matrix. Thanks to the special helical shape of the PTT polymer backbone, the incorporated nano-fibrils of the PTT polymer strengthened the resiliency of the blend fibers. The presence of 10 and 15?wt% of PTT in the blend fibers led to an approximately 20% increase in the resilience behavior, compared to pure PP fibers, with the mechanical properties of the PP matrix preserved. The development of the fibrillar structures during the different steps of the melt spinning process was confirmed by scanning electron microscopy (SEM), and the lowest mean diameter of the nano-fibrils was 64?nm for the hot drawn blend fiber samples consisting of 10?wt% of PTT. In summary, we suggest the optimized blend fiber samples produced in this research will be a promising candidate for a wide range of engineering applications.     

流密码中的布尔函数设计研究进展

密码函数,主要包括单输出布尔函数和多输出布尔函数,在流密码及分组密码系统中扮演着重要角色.在基于线性反馈移位寄存器的流密码系统中为了抵抗各种攻击,一个好的密码函数需要满足以下指标:较高的非线性度、平衡性、低阶相关免疫性、高的代数次数,高代数免疫阶等等.主要总结了近年来在高非线性度弹性密码函数,具有最优代数免疫度的函数和具有良好自相关性质的函数等研究方面的进展,并对其后续工作进行了展望.     

染整加工对氨纶弹力织物弹性的影响

文章探讨了染整加工过程中各主要工艺参数(如温度、时间、碱浓度等)对含氨纶弹力织物的各项性能的影响,并分析染整加工与其弹性性能之间的关系.研究表明含氨纶弹力织物在高温碱性条件下,弹性损伤较为严重;双氧水漂白后织物的强力和弹性损伤较次氯酸钠漂白小;丝光烧碱浓度以不大于240 g/L为宜,此时,织物弹性损伤较小,织物的弹性回复率保持在85%左右.热定型可使含氨纶弹力织物获得较好的定形效果,但当定形温度上升到180℃时,对织物弹性回复率和强力损伤很大,且随定型温度的升高和处理时间的延长,织物有明显的泛黄现象,热定型以温度不大于180℃,时间30～90 s为宜.