Control configuration selection for bilinear systems via generalised Hankel interaction index array

Decentralised and partially decentralised control strategies are very popular in practice. To come up with a suitable decentralised or partially decentralised control structure, it is important to select the appropriate input and output pairs for control design. This procedure is called control configuration selection. It is well known that a suitable control configuration selection is an important prerequisite for a successful industrial control. In this paper the problem of control configuration selection for multiple-input and multiple-output (MIMO) bilinear processes is addressed. First, the concept of the cross-gramian is developed for bilinear systems. The conditions for the existence of generalised cross-gramian are derived. It is shown that if the cross-gramian exists it is the solution to the generalised Sylvester equation. To obtain the cross-gramian in a more computationally efficient way, an iterative method for solving the generalised Sylvester equation is proposed. The generalised cross-gramian is used to form the generalised Hankel interaction index array. The generalised Hankel interaction index array is used for control configuration selection of MIMO bilinear processes. Most of the results on control configuration selection, which have been proposed so far, can only support linear systems. The proposed method supports bilinear processes, takes the effects of dynamics of the process into account and can be used to propose a richer (sparse or block diagonal) controller structure. More importantly, since for each element of generalised Hankel interaction index array just one generalised Sylvester equation is needed to be solved, the proposed control configuration selection method is computationally more efficient than its gramian-based counterparts.     

The Schur stability via the Hurwitz stability analysis using a biquadratic transformation

In this note, it is shown that instead of a bilinear transformation, a biquadratic transformation can be used to determine the Schur stability of a given discrete-time polynomial by determining the Hurwitz stability of the corresponding continuous-time polynomial. However, using a biquadratic transformation, the analysis is not limited by any restriction on the root positions. Several numerical examples are provided to illustrate the procedure.     

Design of bilinear observer for singular bilinear systems

A bilinear observer is proposed for a class of singular bilinear system subject to unknown input disturbance.Based on singular value decomposition technique, the existence of the solution to the decomposed system is presented.Then a bilinear observer is proposed for the decomposed system based on an algebraic Riccati equation, and the domain of attraction of the state estimation error is derived. Finally, a detailed design procedure is given to design a bilinear observer for a model of flexible joint robot, which demonstrates the effectiveness of the proposed method.     

Robust nonlinear generalised predictive control for a class of uncertain nonlinear systems via an integral sliding mode approach

In this paper, a robust nonlinear generalised predictive control (GPC) method is proposed by combining an integral sliding mode approach. The composite controller can guarantee zero steady-state error for a class of uncertain nonlinear systems in the presence of both matched and unmatched disturbances. Indeed, it is well known that the traditional GPC based on Taylor series expansion cannot completely reject unknown disturbance and achieve offset-free tracking performance. To deal with this problem, the existing approaches are enhanced by avoiding the use of the disturbance observer and modifying the gain function of the nonlinear integral sliding surface. This modified strategy appears to be more capable of achieving both the disturbance rejection and the nominal prescribed specifications for matched disturbance. Simulation results demonstrate the effectiveness of the proposed approach.     

On the stability of bilinear free systems

Problems of stability of stationary and nonstationary free bilinear discrete systems over a field GF(p) are investigated. Criteria of asymptotic stability of a system status are found, and some properties of the above-mentioned notions are studied.     

Design of a bilinear fault detection observer for singular bilinear systems

A bilinear fault detection observer is proposed for a class of continuous time singular bilinear systems subject to unknown input disturbance and fault. By singular value decomposition on the original system, a bilinear fault detection observer is proposed for the decomposed system via an algebraic Riccati equation, and the domain of attraction of the state estimation error is estimated. A design procedure is presented to determine the fault detection threshold. A model of flexible joint robot is used to demonstrate the effectiveness of the proposed method.     

基于双线性建模及隐马尔可夫模型的步态识别算法

针对存在两个未知隐含特性的步态识别问题提出了一种新的识别算法,将特性分别看作“内容”和“风格”,对图像序列以状态确定的连续HMM EM估计“内容”类型,引入非对称双线性模型理论对结果建模,通过SVD和NN聚类实现对“风格”的归类判定。实验选择人体两侧轮廓到质心垂线距离作为步态特征,通过在CASIA步态库上的实验证明,该算法能有效提高判别率,对未知风格或内容类型判断有较好的适应性。同时对影响步态识别准确性的其他因素也做了讨论。     

无双线性对的无证书安全签密方案

已有的无双线性对的无证书签密方案,大都存在着机密性漏洞和签名选择性伪造问题。针对此问题,基于有限乘法交换群上的离散对数难题,提出一种无双线性对的无证书签密方案,并进行了安全分析和证明。指出采用随机预言模型的证明方法可能忽略不解决DL难题时对签密方案的攻击,不能证明破解签密方案的难度与解决DL难题相等价。通过对参数的数学分析,证明了破解本签密方案的必要条件是解决DL难题,不存在不解决DL难题攻击本签密方案的多项式时间算法。与已知所有方案相比,所提方案安全性更高。     

基于精确线性化的MIMO双线性系统预测函数控制

针对典型多输入多输出双线性系统, 提出了基于非线性过程精确反馈解耦线性化的预测函数控制方法这是一种分层的控制策略, 首先设计一个静态的非线性状态反馈, 使得闭环系统是输入输出解耦和线性的;然后设计一组单输入单输出预测函数控制器, 下层为上层预测函数控制提供一组单输入单输出模型, 而上层预测函数控制以其固有的鲁棒性来补偿参数变化和解耦线性化的近似性, 并以纸机加压网前箱为例进行了仿真实验, 结果是令人满意的.     

无双线性对的无证书签名方案的分析及改进

对王圣宝等(王圣宝,刘文浩,谢琪.无双线性配对的无证书签名方案.通信学报,2012,33(4)：93-98)提出的不使用双线性配对运算的无证书签名方案进行安全性分析,指出该方案无法抵抗积极不诚实的恶意密钥生成中心(KGC)攻击,并给出了该攻击方式的具体攻击方法。针对这种攻击方式,提出了改进方案,并对改进的方案进行了安全性分析。分析结果表明,改进后的方案在保持原方案高效性的同时,能抵抗恶意KGC攻击,具有更高的安全性,并且改进后的方案不再需要使用安全通道,降低了通信复杂度。     

Comparing digital implementation via the bilinear and step-invariant transformations

From an analog system K, digital systems K_d and K_bt are often obtained via the step-invariant and bilinear transformations, respectively. For the case when K is stable, it is shown that under certain conditions, K_bt converges to K_d in ?_p-induced norms as the sampling period tends to zero for 1?p?∞. Furthermore, K_bt converges to K_d in the graph metric as the sampling period tends to zero no matter whether K is stable or not.     

Stability analysis for time delay control of nonlinear systems in discrete-time domain with a standard discretisation method

This paper provides stability analysis results for discretised time delay control (TDC) as implemented in a sampled data system with the standard form of zero-order hold. We first substantiate stability issues in discrete-time TDC using an example and propose sufficient stability criteria in the sense of Lyapunov. Important parameters significantly affecting the overall system stability are the sampling period, the desired trajectory and the selection of the reference model dynamics.     

Design of sampled-data control for multiple-time delayed generalised neural networks based on delay-partitioning approach

In this paper, we addressed the problem of stability analysis for a class of generalised mixed delayed neural networks by delay-partitioning approach. A novel integral inequality is developed by employing Wirtinger's integral inequality and Leibniz–Newton formula. By constructing an augmented Lyapunov–Krasovskii functional with triple and quadruple integral terms and using some standard integral inequality techniques, asymptotic stability criterion is obtained to the concerned neural networks. By converting the sampling period into a bounded time-varying delays, the error dynamics of the considered generalised neural networks are derived in terms of a dynamic system with sampling. Finally, numerical examples are given to show that the proposed method is less conservative than existing ones.     

Business process redesign at CompuNet—standardizing top-quality service through IT

CompuNet, founded in 1984 in Cologne, Germany, has been regarded as the leader in reselling, networking, maintaining and supporting personal computers in Germany. As a multi-vendor system integrator and maintenance company, CompuNet has recently managed several business process reengineering (BPR) efforts to proactively prepare itself for the competitive environment in fast developing system service market. The case provides background information on the company and its strategic positioning. The study focuses on two successful IT-based BPR initiatives that stress CompuNet's shift from a sales to service orientation, concluding with an in-depth case discussion and a brief outlook.     

Digital workplace transformation: Subtraction logic as deinstitutionalising the taken-for-granted

Digital technology enables the transformation of work and workplaces. Previous digital workplace transformation (DWT) literature has shown how organisations add new digital technologies to create new workplace routines. However, such an emphasis on addition may hinder scholarship from recognising that some established workplace technologies and routines must disappear for new ones to emerge. Adopting the concept of deinstitutionalisation, we examine the rationale for and the process of how an organisation abandons workplace routines that conflict with its intended DWT. Referring to this as subtraction logic, we advance two contributions. First, we conceptualise how deinstitutionalisation of established workplace routines and technologies unfolds in DWT by outlining a process model that synthesises addition and subtraction. Second, we highlight the underlying rationales for DWT. With these insights, we shift the gaze from the dominant addition logic, which advocates for appropriating new digital technologies, to the equally important value of subtraction, i.e., removing existing workplace technologies (or inscribed institutional rules) to abandon workplace routines that conflict with the intended DWT. Hence, our study highlights the oft-ignored subtraction logic in DWT.     

基于Takagi-Sugeno模糊双线性模型的连续搅拌反应釜H∞控制

本文研究了一类连续搅拌反应釜(CSTR)系统的H1控制问题. 系统中的非线性动态特性可采用Takagi-Sugeno(T-S)模糊双线性模型进行描述. 通过引入两个自由矩阵, 给出一个新的保证闭环模糊双线性系统在H1性能指标下全局渐近稳定的充分条件和控制器设计方法, 并且该条件最终可归结为求解一组线性矩阵不等式的可行性问题. CSTR系统的仿真结果表明设计方法的有效性.     

广义霍夫变换的改进

提出基于广义霍夫变换（Generalized Hough Transformation,GHT）的改进算法．与传统方法比较,新方法将参考点设在形状边界上,可以减少内存的需要,并且用于寻找峰值的速度也大大提高．理论上,改进后的算法对内存的需要是一个基于形状描述复杂度的函数,越是精确和高级的形状和特征描述,意味着节省的内存空间越大．最后,将改进的GHT应用于物体形状识别,取得一些实验性效果．     

BPMN到BPEL2.0的模型转换方法

随着WSBPEL2.0规范标准的提出,现有的BPMN到BPEL的组件转换方法已不再适用。为了适应BPEL的变化,对组件的转换进行改动和扩展,对错误处理活动在语义上提供支持,并且提供了显式的事务特性支持。这种设计已经在中国科学院软件研究所软件工程中心研制的OnceBPD建模工具中得到实现,并在实际运用中检验了其可用性。     

水平线在半脆弱性数字水印中的应用

提出一种利用图像自身特征——水平线作为水印的半脆弱数字水印算法。通过考虑人类视觉系统的掩蔽特征,较好地解决水印的透明性与鲁棒性问题,对嵌入前的水印采用Arnold变换,以提高水印的安全性。水印在提取时无需借助原始图像,在定位篡改区域时无需原水印。实验结果表明,该方法在水印透明性与鲁棒性方面具有较好的性能,并能大致确定篡改区域。