A secure authentication with key agreement scheme using ECC for satellite communication systems

Recently, Liu et al came up with an authentication with key agreement scheme for securing communication over the low‐earth‐orbit satellite communication systems. However, this paper demonstrates that this scheme cannot provide perfect forward secrecy or defend against the smart card stolen attack, and has some very bad design defects, making it unpractical. Thus, to design a truly secure authentication scheme for satellite communication systems, this paper presents a new scheme, making use of the advantages of elliptic curve cryptography and symmetric cryptography. The security analyses by the widely used BAN logic and heuristic discussions demonstrate that our new scheme possesses perfect security properties and can defend against various well‐known malicious attacks. Moreover, our new scheme allows users to update passwords locally in accordance with their wishes, achieving a good user experience.     

超光滑加工的后置处理算法研究

为了精确控制超光滑加工过程中磨头的运动轨迹,从而实现光学元件材料去除的均匀稳定,研究了超光滑加工的后置处理算法。分析了超光滑加工工艺的特点和相应的超光滑机床的机械结构,建立了机床的坐标系统,构造了机床的运动学模型。对于光学元件母线为任意平面曲线的情况,研究了磨头运动轨迹的等误差直线逼近算法。在曲率半径为290mm,相对口径为1∶2.9的凹球面上进行了超光滑加工实验。结果表明,利用所述算法可以精确地控制磨头的运动轨迹,从而保证材料去除的稳定性。     

α-苯甲胺基-β-(3-吲哚基)-丙酸甲酯的合成

以L-色氨酸为原料经过4步得到α-苯甲胺基-β-(3-吲哚基)-丙酸甲酯,它是一种具有潜在的抗肿瘤活性的吲哚二酮哌嗪化合物的中间体,首先通过“酰氯法”合成L-色氨酸甲酯盐酸盐,再脱去盐酸,与苯甲醛发生缩合反应形成希夫碱,最后选择性还原,得目的产物,得率54.9%.     

方位远探测声波测井仪数据采集控制软件设计*

方位远探测声波测井技术在近年来得到了快速发展,数据采集控制软件是测井仪器系统的重要功能模块,其主要功能是完成地面采集控制平台与井下仪器的实时命令控制与数据传输。方位远探测声波测井仪数据采集控制软件模块以仪器库的形式挂接到成像测井系统,软件主要由仪器初始化、数据采集、数据分析及处理、仪器参数设置、下发命令封装、文件操作、实时波形绘图显示、实时波形处理、数据回放、帮助系统等部分组成。在程序设计中采用了多线程编程技术,提高与测井主控平台进行交互的时效性以及程序的响应速度。实验室及现场测试表明,方位远探测声波测井仪数据采集控制软件的总体及各个功能模块运行稳定,能够完成现场应用过程中对仪器的控制、数据读取、数据分析及处理、文件记录以及与现场测井采集控制平台的数据接口等需求,为仪器的进一步功能优化升级和现场应用提供了基础。     

An end‐to‐end alternative to TCP PEPs: Initial Spreading,a TCP fast start‐up mechanism

While Transmission Control Protocol (TCP) Performance Enhancing Proxy (PEP) solutions have long been undisputed to solve the inherent satellite problems, the improvement of the regular end‐to‐end TCP congestion avoidance algorithms and the recent emphasis on the PEPs drawbacks have opened the question of the PEPs sustainability. Nevertheless, with a vast majority of Internet connections shorter than ten segments, TCP PEPs continue to be required to counter the poor efficiency of the end‐to‐end TCP start‐up mechanisms. To reduce the PEPs dependency, designing a new fast start‐up TCP mechanism is therefore a major concern. But, while enlarging the Initial Window (IW) up to ten segments is, without any doubt, the fastest solution to deal with a short‐lived connection in an uncongested network, numerous researchers are concerned about the impact of the large initial burst on an already congested network. Based on traffic observations and real experiments, Initial Spreading has been designed to remove those concerns whatever the load and type of networks. It offers performance similar to a large IW in uncongested network and outperforms existing end‐to‐end solutions in congested networks. In this paper, we show that Initial Spreading, taking care of the satellite specificities, is an efficient end‐to‐end alternative to the TCP PEPs. Copyright © 2015 John Wiley & Sons, Ltd.     

一种基于CMA和DDLMS算法的双模式盲均衡算法

为进一步改进盲均衡算法收敛速度慢、稳态误差大、计算复杂度高等问题,提出一种切换模式和加权模式联合CMA(Constant Modulus Algorithm)+DDLMS(Direct Decision Least Mean Square)双模式盲均衡算法.综合切换双模式盲均衡算法和加权双模式盲均衡算法的优缺点,对切换...     

基于隐马尔可夫模型的P2P流量控制管理系统

首先介绍P2P流量的现状,说明现在对于P2P流量要采取疏堵结合的原则。接着介绍P12P流量的管理策略和控制P2P流量的技术,并在对隐马尔可夫模型做了简单介绍之后提出一种基于隐马尔可夫模型的P2P流量控制管理系统。该系统表现出了良好的灵活性和可扩展性。     

均压环螺栓补装工具的研制

均压环是改善绝缘子串电压分布的环状金具。装在均压环上的螺栓,受大风天气及高压输电线路来回摆动的影响,时间久了会造成螺栓的脱落,从而影响线路的使用。为了解决带电作业情况下远距离安装均压环上脱落的螺栓或螺母,设计研制了均压环螺栓补装工具。通过现场应用发现,研制的工具设计合理,结构紧凑,使用方便。     

基于区分性GMM文本无关的话者识别的研究

说话人识别的关键在于如何为集合中的每一个人建立一个能表征该说话人个性特征的声学模型,建模方法将会严重影响系统的性能。基于当今与文本无关的话者识别的主流模型——高斯混合模型（Gaussian Mixture Model,GMM）的基础上,从声学的角度剖析了男女发音的差别,以增加说话人之间的差异性为出发点,引入竞争性思想和通用背景模型（Universal Background Model,UBM）,提出了具有区分性的GMM的建模方法,克服了传统GMM需要大量训练样本的局限性和UBM将说话人强制服从统一分布的弱点。最后实验的对比结果表明,具有区分性的GMM相比传统的高斯混合模型在识别率上有所提高。