一种制造网格环境下的用户代理的签名方案

为提高制造网格环境下用户代理签名的安全性和性能,构建了一种密钥进化的基于身份的签名方案.在该方案中,使用前向安全来解决用户代理的私钥泄漏问题,并在随机Oracle模型下,基于计算Diffie-Hellman假设,形式化证明其安全性;引入基于身份密码学来改进效率,并基于完全二叉树构建,计算复杂度最多是总时间周期的对数;由用户代理自身来更新签名密钥,真正避免了网格用户必须经常在线;而且私钥更新具有前向安全性,当前的私钥泄漏,不会影响以前时间段签名的安全.     

Contourlet域手写签名鉴别特征提取

手写签名验证是一种根据手写笔迹判断书写人身份的一门科学和技术。与联机签名鉴定相比,脱机签名鉴别受设备约束少,具有更广的实用范围。然而,由于脱机签名鉴定丢失了书写过程中的动态信息,鉴定难度大。本文针对脱机手写签名鉴定的特点,提出了基于Contourlet和分形维的特征选取方法,将传统的结构特征与统计特征有机结合起来。运用K-L变换对已提取的特征向量进行降维,最后输入支持向量机进行真伪鉴别。实验结果表明了本文算法的高识别性。     

基于移动代理的复合服务安全方案

给出了用于基于移动代理(Agent)的服务复合的安全方案.该方案以双线性对为基础,利用有隙Dif-fle-Hellman问题的难解性,构造了一个新的数字签名方案,在进行数字签名时不要求移动Agent携带签名密钥,避免签名密钥被窃取.此外,该方案也保证了移动Agent所携带的服务操作参数信息的完整性.同时因其基于身份的特点,在验证Agent生成的签名和Agent的数据完整性时不需要与认证中心或密钥分发中心进行通信.     

面向协同设计的高效自证明多重签名方案

为解决协同设计环境中现有多重签名方案存在的工作效率较低和资源占有率偏高等问题,提出并实现了一种基于椭圆曲线密码体制的高效多重签名方案.通过引入公钥自证明思想和预计算步骤,将用户身份认证和数字签名验证有机结合在一起,无需繁琐的身份鉴别认证操作,也无需可信数字认证中心,只需要一次操作即可直接完成数字签名的验证工作.分析及实验表明,该方案结构简单,能有效抵抗目前已知的各种攻击,具有较高的工作效率、较低的资源占有率和较强的安全性.     

基于高效短签名的自动售货机安全交易协议

基于物联网和大数据技术的自动售货机是目前"新零售"的一个热门方向。针对当前自动售货机存在的漏洞会严重影响厂商利益和用户隐私安全这一问题,设计了一种由App客户端、云管理中心和自动售货机组成的售货系统,提出一个高效安全的基于身份的短签名方案,并以此为基础设计了一种基于高效短签名的自动售货机安全交易协议,实现了自动售货机的安全控制和管理。通过对自动售货机自动出货过程进行测试,仿真结果表明签名过程数据量小、计算速度快,协议具有较高的效率和安全性。     

网格化制造模式中基于身份的认证协议研究

为解决当前网格安全基础设施过程繁琐,导致网格化制造规模受限的问题,提出了网格化制造身份认证层次结构.该结构完全摒弃了数字证书,紧密结合了网格制造化环境.基于该结构,进一步提出了网格化制造模式中基于身份的加密与签名方案和基于身份的认证协议.仿真实验表明,基于身份的认证协议比安全套接层认证协议更轻量、更高效,大大减轻了用户端负担,有助于网格化制造规模的扩大.     

前向安全的新型门限数字签名方案

为得到电子商务中高效、安全的数字签名方案,在改进后的Schnorr签名方案的基础上,提出一种新型门限数字签名方案,其最大特点是满足成员单独签名并具有前向安全性。为防止签名权力被滥用,方案采取二次分割的方式对密钥进行分配,成员必须与签名中心合作才能完成签名,确保方案具备可审计性并能抵御成员合谋攻击;为提升方案的鲁棒性,成员与服务器在签名过程中执行Joint-Shamir-RSS协议,共享关键随机参数k,保证了签名过程的安全性并使得方案能够抵御外部攻击。与同类方案相比,所提方案具有密钥分发简单、签名过程高效、可动态增删成员等优点。     

锅炉给水泵不同形式轴封的能效和投资回报分析

锅炉给水泵的轴封系统主要采用机械密封,此外,浮动环密封和迷宫密封的使用也很普遍。本文在分析浮动环密封和迷宫密封结构形式、机理和特点的基础上,分别基于最小泄漏损失和最低投资原则设计了两种用于锅炉给水泵的轴封方案,并利用理论计算的方法分析、对比了两种方案的能量损耗及投资回报。结果表明:应用浮动环密封的锅炉给水泵轴封系统相对迷宫密封,能量损失更小、初始投资高但运行能耗成本低,在电机和汽轮机两种驱动条件下,分别运行2.2月和5.3年的时间后,两者的总成本将趋于相等。本文研究成果可为锅炉给水泵轴封系统的选择提供指导。     

面向网络化制造环境的多功能门限数字签名

为了保证网络化制造环境中信息交换的基本安全需求,提出一个全新的多功能门限数字签名方案.该方案通过结合门限、信息隐藏和指定验证者三种方法,使其不但具有门限签名的功能,可以满足特殊情况下的多人签名,而且能够隐藏信息、指定信息恢复者和签名验证者,实现以多用户协作的方式对共享信息的真实性和来源进行认证.在随机预言模型下,证明了方案的安全性,并给出严谨的数学推导和安全强度下限.最后,通过与相关方法的对比,说明了该方案的有效性.     

基于手写签名的电子公文安全认证方案设计

针对基于数字签名的电子公文安全认证中存在的不安全因素,提出一个基于手写签名的电子公文安全认证方案.该方案把人体生物特征即在线手写签名和数字签名相结合进行身份认证,可以有效抵御认证过程中潜在的各种攻击,同时利用信息隐藏技术进行安全通信,为电子公文安全提供可靠保障.     

CAD系统中签名管理的设计与实现

利用公开密钥数字签名技术 ,针对 CAD系统中签名的要求提出了一种有效的解决方案 ,即集中式密钥管理技术 ,并给出了相应的实现方法。     

可调向心涡轮增压器调节机构优化设计

提出了一种新型的增压器调节机构设计方案,该设计方案取消了传统增压器调节机构中的喷嘴座或定距套结构,利用3个固定导叶来控制喷嘴环的宽度。该设计方案力图减小蜗壳或导叶流道中由于特定结构所导致的局部扰动,减小其流动损失,提高涡轮效率。对该设计方案与喷嘴座结构方案、定距套结构方案进行了相同工况的数值计算,通过计算结果的对比,从理论上验证了设计方案的可行性。     

A novel instrumented ring for the measurement of grip force adjustments during precision grip tasks

A wide range of scientific and clinical research studies use the measurement of grip force to quantify hand function and activities during daily living. Many applications of instrumented objects can be found in the biomechanical and neurophysiological literature. However, these were found not to be suitable for the measurement of grip force and force modulations during precision grip independently from the hand orientation. The low-cost precision grip force transducer described here is capable of recording magnitude, direction and modulation of the force exerted on a closed ring. The design is based on a standard proving ring, onto which a second set of strain gauges is applied. The outputs of both Wheatstone bridges yield a unique signature for every position under a two-point load. The tested aluminium ring had an outer diameter of 83 mm, a wall thickness of 3 mm and a height of 12 mm. With eight single bending strain gauges used, the maximum load was 100 N. During a grip task, tremor components from d.c. to 45 Hz could be detected. The newly developed ring might therefore find a use in many biomechanical and neurophysiological studies as a tool for measuring grip force and its fine modulations.     

Real-time synchronization method based on dual ring fieldbus in CNC system

As the popularization of dual ring fieldbus, the optimized dual ring synchronization methods are still in short. The current synchronization methods are generally established in traditional industrial fieldbus, in which transmission is commonly considered in single track, the two-way transmitting cannot take full effect, and would result in unwanted idle load on equipment lines. In stamp-transferring part, the synchronizing algorithm is not properly processed to diminish the latency, so the real-time performance of entire system cannot be ensured. To support the synchronization control of stations in the CNC system, a real-time time synchronization method for dual ring fieldbus in the CNC system is designed in this paper. In this method a synchronizing message transmission scheme based on dual ring architecture and the synchronization algorithm between master and secondary stations are integrated. In the scheme, the clock models of both master and secondary stations are optimized with corresponding modules and the stamp data transmission based on the dual ring fieldbus is devised exclusively, so the transmitting efficiency improves with less idle work. In the algorithm, all the secondary stations can accomplish the consistent state with master station by updating clock discrepancy information in one communication cycle, and it takes the advantage of two-way transmitting and makes the best use of dual ring structure, so the real-time performance of the system can be promoted while retaining the precision of synchronization. To evaluate the performance, the costs of the method and errors during synchronizing are noted and analyzed based on the actual running environment in the industrial fieldbus. The results show that it reduces communication cost and ensures the smoothness of the system with low lag effects under heavy load. The proposed time synchronization method optimizes the architecture of sync message transmission in dual ring fieldbus, and improves the efficiency of time synchronization in the stations of CNC system.     

无可信PKG的基于身份的批量群签名

针对密钥托管困难的问题，对已有的基于身份的群签名的密钥生成算法及签名方案进行了改进，提出了无可信密钥生成中心（PKG）的基于身份的批量群签名方案，其主要利用了椭圆曲线上的双线性映射及批量签名的思想。研究结果表明，与已有相关文献相比，该方案在效率、安全性等方面都有了明显的提高。     

一种基于负熵的舰船轴频电场信号检测方法

轴频电场是运动舰船在海水中产生的一种重要的物理场,它具有明显的线谱特征,是很难被隐身的舰船特征信号。运用Q-Q图法和Epps-Pulley方法对实测的海洋环境电场的高斯性进行了检验,检验结果表明环境电场具有良好的高斯性,在此基础上,将负熵准则应用于舰船轴频电场信号检测中,利用目标信号和环境噪声在负熵域上的显著差别,使用浮动门限将目标准确地检测出来。实测数据的处理结果证明了方法的有效性和优越性。     

A practical method for finite element ring rolling simulation using the ALE flow formulation

Finite element ring rolling simulation by conventional Lagrangian codes carries an excessive computational cost. The main reason for this is the large number of incremental stages typically required to complete a full simulation. The nature of ring rolling however means that the amount of deformation taking place in a given increment is relatively small compared with typical metal forming processes. This paper describes measures that make the analysis of ring rolling a practicable proposition. The resulting model is based on a threefold approach, comprising the finite element flow formulation, an arbitrary Lagrangian Eulerian update strategy, and a novel iterative solution scheme called the successive preconditioned conjugate gradient method. The approach exploits the slowly evolving nature of the problem with the effect of reducing the time penalty for each deformation increment. In addition, a number of issues specific to ring rolling have been addressed including the problem of how the mandrel interface is dealt with for arbitrarily shaped rollers. The importance of addressing this particular issue is also illustrated. The method is validated by comparison with earlier experimental work and previously developed models for both pure radial, and radial–axial ring rolling.