USB密码钥匙漏洞分析及防御策略的研究

随着我国网络银行业务的不断普及,网络上的金融犯罪也日益猖獗.因此,以PKI系统为基础的安全身份认证体系也在逐步得到广泛的关注.PKI系统的一个关键安全因素是私钥的保密,但用于存储证书和私钥的USB密码钥匙仍然存在着安全漏洞,使得系统很可能成为木马攻击的对象.首先分析了基于USB密码钥匙的PKI系统的工作原理及其存在的安全漏洞,其次针对这些漏洞提出切实可行的防御策略.     

A Unified Approach to Model-Reference Adaptive Systems Part I: Theory

A unified approach to model-reference adaptive control systems is presented. A linearized error equation for each adaptive system is derived about some operating point and converted into the standard form for plotting root loci. The contribution made here is to convert the selection of an adaptive technique and the choosing of adaptive coefficients for some desired system performance from a "mystical art" to standard control techniquess.     

A fuzzy sliding-mode controller design for a synchronous reluctancemotor drive

A new method for controlling a synchronous reluctance drive system using a sliding mode with fuzzy controller design is presented. The fuzzy controller is used to adjust the sliding line of the sliding-mode controller. Using this method, the system has a fast response and a good disturbance rejection capability. In addition, the chattering of the speed is reduced. In this work, the mathematical model of the motor is described first. Then, the design procedures for a high performance drive system using a sliding mode with fuzzy control are explained. Next, the system enhanced by a high performance 32 bit digital signal processor (DSP) and simple hardware circuits is shown. Both the current-loop and speed-loop controllers are executed by the DSP. Finally, some experimental and computer simulation results are presented. The experimental results validate the simulation results     

一种基于LMI的航空发动机输出反馈PI控制

基于LMI(LinearMatrixInequality,线性矩阵不等式),提出一种航空发动机PI输出反馈控制器设计方法。利用被控对象中控制向量2范数上界的限制,提出了一种改进ILMI(IterativeLMI)算法,用于解决控制受约束的航空发动机PI控制器的一种LMI描述求解问题。以某型双转子涡喷发动机为被控对象,基于LMI进行了PI输出反馈控制器的设计,并分区域在飞行包线进行了航空发动机控制系统仿真验证。结果表明,所得控制器满足预期设计要求,同时具有一定鲁棒性。     

Unmanned space vehicle navigation by GPS

In this paper, flight-path deviation in the navigation of unmanned space vehicles by global positioning system (GPS) is analyzed. A new method to calculate flight-path deviation by means of coordinate transforming is presented and the software of navigation and control is designed. This software is practical and effective for navigation by GPS with some characteristics including high-speed, high accuracy, real-time positioning and the use of digital mapping technique     

飞机／发动机推力矢量综合控制方法的探讨

根据已有研究成果,给出了飞机/发动机推力矢量综合控制系统的结构与控制逻辑,提出了研制飞机/发动机推力矢量综合控制系统对矢量喷管控制的要求和实现方法,最后对研制工作提出了建议.     

一个新的实时光学图像识别系统

本文描述了一个新的实时光学图像识别系统。该系统主要是激光二极管、多换能器声光器件、电荷耦合器件以及光学透镜组成的。这个系统既不需要相干光输入图像,也不需要基准图像的付氏变换金息图。不同波段成像系统输出的实时视频图像信号和事先记录的或实时截获的基准图像均可施加给本系统。文中给出了理论分析以说明工作原理。实验结果证实这种非相干光相关器具有完成实时图像识别的能力。事实上,某些图像识别任务碰到的图像位移、尺寸、旋转不变性问题,本系统可容易地予以解决。     

Maneuvering Target Tracking with Hypothesis Testing

A new approach is proposed for maneuvering target tracking.Target motion is described by nonlinear models in a sphericalcoordinate system. States of these models are estimated byquantization, multiple hypothesis testing, and a suboptimumdecoding algorithm of information theory. This approach does notrequire linearization of nonlinear models. Hence it is superior toclassical estimation techniques, such as the extended Kalman filter.Simulation results, some of which are presented here, haveshown the superiority of the proposed approach over target trackingwith the extended Kalman filter.     

跨声速风洞全模颤振试验技术

介绍了跨声速全模颤振试验的发展现状和存在的问题。探讨了全模颤振试验对风洞和支撑系统等试验设备的要求。对于风洞,主要从风洞洞体和流场等方面分析了进行颤振试验所需要具备的性能,并以中国空气动力研究与发展中心的2.4m跨声速风洞为例,介绍了进行颤振试验必须要采取的控制措施。对于支撑系统,则从模型运动自由度、支撑系统稳定性和支撑系统频率等方面的要求,阐述了设计支撑系统的困难,并简要分析了目前国内外发展的多种全模颤振支撑系统的结构原理及其优缺点。然后介绍了系统安全的保证措施,包括支撑系统稳定性分析、风洞紧急停车控制系统和模型保护装置等。最后根据飞行器发展的需求,探讨了今后需要完善和发展的几个主要问题。     

基于火箭橇的北斗动态定位精度鉴定方法

介绍了几种现有的以GPS/北斗为主要代表的卫星导航系统的动态定位精度 鉴定方法,分析了这几种方法在模拟实际使用环境、鉴定精度等方面的优缺点,提出了 一种基于火箭橇试验平台的北斗导航定位系统动态定位精度鉴定方法。该方法能够很好 地模拟北斗导航定位系统实际工作环境（速度、加速度、振动和天线角度等）,解决高 动态、高精度北斗导航定位系统动态定位精度鉴定问题,并对该方法的原理和实施方法 作了详细的论述,最后分析了该方法的不确定度及误差,并提出了改进措施。     

A Postdetection Method of Measuring Predetection RF Signal-to-Noise Ratio

A method of determining the predetection signal-to-noise power ratio in a radio receiving system by measurement of average postdetection signal-plus-noise and noise-only voltages (dc output of the detector) is described. The principle has actually been known for many years, but does not seem to be well known or widely used, possibly because of some associated computational difficulties. Some digital computer tabulated results are presented which remove these difficulties, and measurement techniques are discussed. The calculation of expected signal-to-noise ratio for radio and radar systems is briefly reviewed.     

三维机身外形快速生成及表面分块

 本文提出了纵向放样线作锥线链的最小二乘法拟合,剖面外廓线作圆弧、椭圆弧及直线混合融合计算的三维机身外形生成方法。在SIEMENS 7.760机上建立了包含计算机绘图在内的FORTRAN程序。可以方便而快速地生成构形复杂的三维机身外形及气动力面元法分析所需的表面小块。几个算例证实了本法的通用性、快速性及简便性。程序发展后可能作为CAD中的图象主尺寸系统。     

适合航天飞机应用的星体跟踪器

本文推导了航天飞机采用新型探测器件——电荷耦合器件CCD（ChargeCoupled DeVices）组成的星体跟踪器进行姿态稳定的公式。并提供一种适合航天飞机应用的星体跟踪器原理样机。     

Modeling the influence of inter-blade connections and variable rotor speed on the aeromechanical stability of a helicopter

A method of modeling the effect of inter-blade connections and variable rotor speed on the aeromechanical stability of helicopters is presented. The model incorporates twelve degrees of freedom. The new effects that are investigated in the present study result in a system of equations of motion that the usual Multiblade Coordinate Transformation (MCT) cannot deal with. Therefore, suitable coordinate transformations are defined: The Modified Multiblade Coordinate Transformation (MMCT) and the Extended Multiblade Coordinate Transformation (EMCT). These transformations are derived and their implementation is presented. A large part of the derivation is carried out using a symbolic algebra software. An eigenvalue analysis of the final linearized transformed equations defines the aeromechanical stability. Finally some preliminary results are presented that help in validating the model and pointing out the importance inter-blade connections and variable rotor speed can have on the dynamics of the system.     

一种用于ISA总线计算机1553B接口模块的设计

介绍一种用于ＩＳＡ总线计算机的低成本的１５５３Ｂ总线接口模块的设计,该设计使得１５５３Ｂ终端具有与美国ＤＤＣ－ＩＤＥＡ产品类同的功能,可进行１５５３Ｂ产品或系统的开发、仿真。简要介绍了模块的硬件设计和软件配置,罗列了其设计特点。     

巡航导弹飞行撞地概率的一种计算方法

研究了巡航导弹飞行高度控制系统对应的高度控制误差和地形起伏误差,在综合这两种误差的基础上,提供了一种飞行撞地概率的计算方法,并给出了飞行高度与之对应的撞地概率计算实例。计算和分析得出,参考航迹高度取现行标准值的某型巡航导弹撞地概率太大,需通过减小高度探测控制系统的误差或者增大参考航迹的规划高度来降低撞地概率。     

带弹性阻尼支承的转子系统丢失叶片瞬态响应试验研究

本文对带弹性阻尼支承的转子系统由于丢失叶片产生的瞬态响应给出了系统的实验研究结果。进行了不同转速和不同挤压油膜阻尼器(SFD)油膜间隙情况下转子上施加不同的突加不平衡量的实验。在阻尼器处由极限圆表征的不稳定门限值可以确定;全面地观察到转子系统由于非线性引起的一些特殊现象,如“锁死”、双稳态跳跃和亚协调进动等。分析了SFD抑制转子系统不稳定的有效性和能力。      

某超高速转子系统减振结构研究

为解决某超高速转子系统的失稳碰摩问题,以干摩擦阻尼耗散转子涡动能量理论为依据,采用一种自由安装式干摩擦片减振结构(干摩擦阻尼器).该结构在转轴上安装波形弹性垫片及干摩擦片,通过螺母预紧力矩向波形弹性垫片及各干摩擦片提供轴向正压力.干摩擦片随转子振动并产生相对运动,从而耗散转子涡动能量,达到减振、增强转子稳定性的目的.通...     

喷气发动机转速数字控制器优化设计

喷气发动机转速数字控制系统的构成和动态模型如图1所示。数字控制器由微机编程实现。该闭环系统由PID控制器进行串联校正、角度负反馈为位置反馈校正。