一类新的时滞混沌系统及其最小能量引导控制

提出了一类时滞混沌系统.从最大Lyapunov指数、相图和分叉图3个方面,揭示这类系统随其参数变化所产生的丰富动力学行为,并发现了大幅度拟周期(弱混沌)振荡现象,分析了这种振荡在工业中的危害以及可能的用途.提出了异时滞的高维混沌系统间的同步控制问题,并提出一种基于变增益反馈的最小能量控制法,用线性反馈控制器实现了快速的引导控制.因为反馈增益由一个小量随着同步误差的减小逐渐增大,本文提出的控制器可以有效减小控制所需的能耗.     

凸多面体不确定随机时滞系统的参数依赖状态反馈控制

考虑了凸多面体不确定随机时滞系统的参数依赖状态反馈控制问题.把参数相关的Lyapunov-Krasovskii泛函方法和自由权矩阵方法相结合,得到了基于线性矩阵不等式(LMI)的时滞相关及参数相关的鲁棒镇定的充分条件.由于在引入自由权矩阵时,减少了所用的自由矩阵数目,使得给出的参数依赖的控制器更易于实现.最后用例子说明了结果的有效性.     

Reliable control for linear systems with time-varying delays and parameter uncertainties

In this paper, reliable control for linear systems with time-varying delays and parameter uncertainties is considered. By constructing newly augmented Lyapunov–Krasovskii functionals and utilizing some mathematical techniques such as Leibnitz's rule, Schur's complement, reciprocally convex combination, and so on, a reliable controller design method for linear systems with time-varying delays and parameter uncertainties will be suggested in Theorem 1. Based on the result of Theorem 1, a non-reliable stabilization criterion will be presented in Corollary 1. Theorem 1 and Corollary 1 are derived within the framework of linear matrix inequalities(LMIs) which can be easily solved by utilizing various optimization algorithms. Two numerical examples are included to show the effectiveness and necessity of the proposed results.     

A critical analysis of weld heat input measurement through a water-cooled stationary anode calorimeter

Comprehensive models of heat transfer require specification of the total amount of heat received by the workpiece. The objective of this work was to critically examine the use of a water-cooled stationary anode calorimeter to obtain both arc efficiency and total heat input into the workpiece. For simplicity and clarity, this last quantity is called the gross heat input. The effects of current, material type and water flow rate on the calorimeter performance were determined experimentally. Some measures for reducing errors in calorimetry were evaluated. Improvements were made to reduce heat losses from the top surface of the test coupon and boost heat removal from the opposite surface. A sensitivity test was conducted to estimate the effect of measurement inaccuracies. The results demonstrate the effectiveness of calorimetry for measuring gross heat input in arc welding.     

Homing a robot with range-only measurements under unknown drifts

The problem of homing a mobile robot to a given reference location under unknown relative and absolute positions is addressed in this paper. This problem is easy to solve when all the positions and kinematic variables are known or are observable, but remains a challenge when only range is measured. Its complexity further increases when variable and unknown drifts are added to the motion, which is typical for marine vehicles. Based on the range measurements, it is possible to drive the robot arbitrarily close to the reference. This paper presents a complete solution and demonstrates the validity of the approach based on the Lyapunov theory. The use of models, which are often affected by uncertainties and/or unmodeled terms, is intended to be minimal and only some constraints are imposed on the speed of the robot. We derive a control law that makes the robot converge asymptotically to the reference and prove its stability theoretically. Nevertheless, as it is well known, practical limitations on the actuation can weaken some properties of convergence, namely when the system dynamics require increasing actuation along the approach trajectory. We will demonstrate that the robot reaches a positively invariant set around the reference whose upper bound is determined. Finally, we conclude our work by presenting simulation and experimental data and by demonstrating the validity and the robustness of the method.     

风险分析及不确定性因素临界点的求法

推荐一种建立在最小二乘法原理基础上的求得不确定性因素临界点的方法。为了便于电算，对计算公式进行了推导，并将推导结果编入了程序。这样，计算机在完成敏感度分析后即自动进行临界点的计算，并可在瞬间完成，简便易行，结果可靠。     

矿业海外投资的风险因素分析

在海外投资矿业受很多不确定性因素的影响,风险因素较多。针对我国目前存在的风险控制现状,研究这些风险因素,对于合理开发矿业项目,有效防范矿业开发风险,确保我国经济安全运行具有重要意义。     

考虑多重不确定性因素的售电公司购售电决策模型

售电公司参与市场交易面临着负荷、现货价格及需求响应等多重不确定性,综合考虑多重不确定性因素并根据其特点进行建模有利于提高购售电决策的有效性.首先,提出分时电价下计及用电成本满意度和用电舒适满意度的可转移负荷响应优化模型;其次,考虑用户响应行为的不确定性,建立基于模糊隶属度函数和消费者心理学的可削减负荷响应模型;然后,分...     

考虑双重不确定性的公交时刻表分布鲁棒优化模型

城市公交系统由于受外界干扰,其需求和运行环境在时空上呈现高度不确定性,给日常运营组织带来了巨大挑战.为增强公交系统对于客流需求和运行场景双重不确定性的应对能力,提出一种权衡服务质量和服务鲁棒性的单一线路时刻表优化方法.方法采用离散场景集刻画需求的不确定性,并以滞留人数的期望值和条件风险值最小化为目标,综合考虑多方面约束,构建多场景耦合的分布鲁棒优化模型(DRO).为方便模型求解,运用模糊集描述场景发生概率的不确定性,再借助对偶理论和常规线性化方法将原模型转化为等价的混合整数线性规划形式.最后通过实际案例对方法进行分析,结果表明:等价转换得到的线性形式可由GUROBI优化软件快速求得最优解; DRO模型所得时刻表能有效应对双重不确定性;随着不确定性的上升,分布鲁棒优化方法相较于传统随机规划方法体现出更强的鲁棒性,可以切实改善公交系统运营的稳定性.