A review on some classes of algebraic systems

ABSTRACT

In this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory.     

基于双线性内插算法的多路视频的缩放设计

基于双线性内插算法,设计改进了一种以FPGA为硬件平台的多路视频信号的图像缩放装置.把与期望位置相邻的两行像素缓存在RAM中,先对垂直方向进行插值运算,再对水平方向进行插值运算.利用FPGA并行处理的优势实现多路视频信号的实时缩放.     

基于Laguerre滤波器等价设计的IIR宽带波束形成

常规IIR宽带波束形成器可以获得比FIR宽带波束形成器更好的性能,但其需要多极点的自适应调整过程,存在稳定性无法保证,计算复杂度较高等问题.本文提出一种新的基于IIR滤波器的宽带波束形成算法.该算法基于高阶Laguerre宽带波束形成器,利用双线性变换和函数束方法设计相应的低阶等价IIR宽带波束形成器.仿真实验及理论分析表明,该方法无需常规IIR宽带波束形成器的多极点自适应调整过程,在保证算法稳定性的同时,减少了计算复杂度,并提高了输出信干噪比(SINR).     

Three-stage least squares-based iterative estimation algorithms for bilinear state-space systems based on the bilinear state estimator

Because of the product item of the control input and the state vector, the identification of bilinear systems is difficult. This paper considers the combined parameter and state estimation problems of bilinear state-space systems. On the basis of the observability canonical form and the model transformation, an identification model with a linear combination of the system parameters is obtained. Using the hierarchical principle, the identification model is decomposed into three submodels with fewer variables, and a three-stage least squares-based iterative (3S-LSI) algorithm is presented to estimate the system parameters. Furthermore, we derive a state estimator (SE) for estimating the unknown states, and present an SE-3S-LSI algorithm for estimating the unknown parameters and states simultaneously. After that, the least squares-based iterative algorithm is presented as a comparison. By analyzing the estimation results and the calculation amount, these two algorithms can identify the bilinear system effectively but the 3S-LSI algorithm can improve the computational efficiency. The simulation results indicate the effectiveness of the proposed algorithms.     

钒自给能探测器延迟信号数字处理算法与实验研究

钒自给能探测器（VSPND）输出电流信号的慢响应特性严重影响反应堆内中子通量的实时测量，不利于反应堆的控制和安全管理。采用反函数计算或各种补偿方法改进其响应特性，有利于VSPND的使用。本文研究了前向差分变换法、后向差分变换法、阶跃响应不变法及双线性变换法等4种数字处理算法，提出了两次处理的方法，有效缩短了VSPND输出信号的响应时间，时间常数由325.47 s减少到7 s以内，其中阶跃响应不变法算法的时间常数最小为5.2 s。设计了数字实验系统，验证了算法的正确性，为该探测器用于反应堆内中子通量测量的快速响应提供了可行性。     

大型直缝焊管三点弯曲JCO成形及弹复解析

采用三点弯曲JCO成形方法制造大型直缝焊管的技术关键是板坯每道次弯曲角的弹复控制,其成形角的精度直接制约着成形管坯的椭圆度.针对管线钢材料的特点,采用双线性硬化材料模型,基于小变形假设,建立了每道次弯曲成形及弹复计算模型,得到了对应任一凸模行程处板料中性层上任一质点卸载前后的转角和挠度数学表达式.理论和实验数据均表明,弯曲角和成形角之间非常接近线性关系,验证了理论解析的正确性.     

On the reachability of a class of continuous bilinear systems

Abstract

It is well known that using differential geometric methods, the reachability of nonlinear systems can be checked via Lie algebra. Normally, the resultant checking condition is state dependent and requires complicated recursive Lie bracket operations. In this paper, it is shown that for dyadic bilinear systems, the reachability property is actually state independent, and hence a global property of the system. Specifically, it is proved that the Lie algebra condition is equivalent to the rank conditions of two constant matrices. As examples, the reachability of two real‐world systems is examined through the new checking condition.     

基于B+树的动态数据持有性证明方案

针对云存储环境下的数据持有性证明（PDP）方案效率较低、不能很好支持全动态更新的问题，设计了一种基于B⁺树的动态数据持有性证明方案。该方案引入双线性对技术和数据版本表，支持用户进行数据块级的细粒度动态操作并能保护用户的数据隐私。通过优化系统模型并设计节点索引值，使第三方检测机构能识别错误数据并进行精确定位。理论分析及实验结果表明，与基于Merkel哈希树（MHT）的方案相比，所提方案能够显著降低系统构造认证数据结构的时间开销，并且简化了动态更新过程，提高了第三方检测机构的验证效率。     

基于身份代理权可撤销的代理签名

代理签名体制中代理签名权的撤销问题至关重要,SONG等人提出一种可撤销代理权的代理签名方案。提出了一种新的基于身份的可撤销代理权的代理签名方案,原始签名者在发现代理签名者不诚实时,可以通过可信中心TA及时有效地撤销代理签名者的代理签名权,且在该方案中将用户个人信息作为身份标识,大大减少了密钥的存储和管理开销。