Suboptimal reliable guaranteed cost control for continuous-time systems with multi-criterion constraints

The suboptimal reliable guaranteed cost control （RGCC） with multi-criterion constraints is investigated for a class of uncertain continuous-time systems with sensor faults. A fauk model in sensors, which considers outage or partial degradation of sensors, is adopted. The influence of the disturbance on the quadratic stability of the closed-loop systems is analyzed. The reliable state-feedback controller is developed by a linear matrix inequalities （LMIs） approach, to minimize the upper bound of a quadratic cost fimction under the conditions that all the closed-loop poles be placed in a specified disk, and that the prescribed level of H∞ disturbance attenuation and the upper bound constraints of control inputs＇ magnitudes be guaranteed. Thus, with the above muki-criterion constraints, the resulting closed-loop system can provide satisfactory stability, transient property, a disturbance rejection level and minimized quadratic cost performance despite possible sensor faults.     

Delay-dependent robust control for uncertain discrete singular systems with time-varying delay

The design problem of delay-dependent robust control For uncertain discrete singular systems with time-varying delay is addressed in this paper. The uncertainty is assumed to be norm-bounded. By establishing a finite sum inequality based on quadratic terms, a new delay-dependent robust stability condition is derived and expressed in terms of linear matrix inequalities （LMIs）. A suitable robust state feedback control law is presented, which guarantees that the resultant closed-loop system is regular, causal and stable for all admissible uncertainties. Numerical examples are given to demonstrate the applicability of the proposed method.     

Input-output approach to robust stability and stabilization for uncertain singular systems with time-varying discrete and distributed delays

Based on input-output approach, the robust stability and stabilization problems for uncertain singular systemswith time-varying delays are investigated. The parameter uncertainties are assumed to be norm-bounded and the time-varying delays include both discrete delay and distributed delay. By introducing a new input-output model, the time-delay system is embedded in a family of systems with a forward system without time delay and a dynamical feedback uncertainty. A sufficient and necessary condition, which guarantees the system regular, impulse-free and stable for all admissible uncertainties, is obtained. Based on the strict linear matrix inequality, the desired robust state feedback controller is also obtained. Finally, a numerical example is provided to demonstrate the application of the proposed method.     

线性遗产视角下黄河文化遗产的特征及保护策略

黄河文化遗产类型多样、数量庞大,形成了体量巨大的文化遗产集群,其发生发展的物质基础、依托的线性要素、文化内涵等均有相同之处,具有线性遗产的特征。“黄河文化遗产系统保护”既是黄河流域生态保护与高质量发展这一国家战略的重要内容、黄河文化遗产保护的基本要求和关键理念,也是科学、高效的保护策略。但是,黄河文化遗产的保护存在诸多问题,包括内涵不清,多头并管、各自为政,点状、分散的保护理念和模式与黄河文化遗产的特征不适宜,合力不足等。为此,有必要设置专门的黄河文化遗产管理机构、多举措推动黄河文化遗产的系统保护、以“增权”提升公众参与的动力和能力,从而提高黄河文化遗产的保护水平及效果。     

《线性代数》课程教学改革的实践与思考

《线性代数》在自然科学与社会科学的各个领域发挥着越来越重要的作用,但大学里的课堂教学与现实中的实际应用存在着一定的脱节。本文从线性代数课程的教学现状出发,提出了在教学内容、教学方法及教学手段上进行改革的一些建议。     

Evaluation of the optimum pre-stressing pressure and wall thickness determination of thick-walled spherical vessels under internal pressure

In the present study, in the first part for a spherical vessel with known dimensions and working pressure, two methods of hoop and equivalent stress optimization across the wall thickness are employed to determine the best autofrettage pressure. In the next part for a predefined working pressure the minimum wall thickness of the vessel is calculated using two other design criteria i.e. (A) optimizing the hoop stress, and (B) assuming a suitable percent for the penetration of yielding within the wall thickness. Finally, the optimum thickness and the necessary strengthening pressure are extracted and different plots are introduced for different types of structural materials under different internal pressures.     

线性相关模型及其估计

根据社会经济研究领域中相关变量及其观测数据的特点,吸收回归分析中模型描述分析的思想,提出相关模型描述分析的方法,用于讨论线性模型及其估计的方法。     

Mathematical models for academic webs: Linear relationship or non-linear power law?

Previous studies of academic web interlinking have tended to hypothesise that the relationship between the research of a university and links to or from its web site should follow a linear trend, yet the typical distribution of web data, in general, seems to be a non-linear power law. This paper assesses whether a linear trend or a power law is the most appropriate method with which to model the relationship between research and web site size or outlinks. Following linear regression, analysis of the confidence intervals for the logarithmic graphs, and analysis of the outliers, the results suggest that a linear trend is more appropriate than a non-linear power law.     

利用MATLAB设计线性二次型最优控制器

本文通过实例介绍用MATLAB设计线性二次型最优控制问题的基本方法，并研究了参数变化对最优控制系统设计的影响。     

线性变换与其伴随变换的性质讨论

文章主要讨论了线性变换与其伴随变换的关系及伴随变换的相关性质.