线性时滞不确定系统的时滞相关鲁棒镇定

讨论了同时具有输入时滞与状态时滞的不确定线性系统的时滞相关鲁棒镇定问题.运用矩阵分解思想和Lyapunov-Karsovskii泛函方法,在处理V的导数时添加一个恰当的0项,引入自由权矩阵,基于LMI方法获得了系统经无记忆状态反馈后可鲁棒镇定的时滞相关充分条件,同时获得了具体的控制器设计方法.数值例子说明所得结论具有较小的保守性.     

浮桥运动响应分析的非线性间隙单元构造与应用

因浮桥接头动力响应的复杂性, 至今仍未找到一种通用的方法模拟接头的动力特性, 使得对浮桥进行建模并求解其的动态响应时存在较大困难。利用杆单元模拟接头的抗拉和抗压特性, 并利用梁单元的抗弯特性, 把两者结合组成非线性混合单元, 可以较好地模拟接头的特性和求解浮桥的动态响应。对数值计算和已有的模型试验结果的分析发现, 在快速通载时非线性连接浮桥会发生位移波堆积效应。     

基于协同仿真技术的车辆非线性平顺性分析

汽车悬架中存在多种非线性因素,采用非线性模型的时域求解可获得更准确的平顺性分析结果.考虑到单一软件的局限性,本文采用协同仿真技术分析非线性车辆模型的平顺性.用机械系统软件ADAMS建立汽车多体模型,并用MATLAB/Si mulink的S函数建立路面模型、轮胎模型和驾驶员模型.以随机生成的路面不平度数据为输入,在Si mulink环境下建立协同仿真模型并完成车辆非线性模型的时域求解.给出了平顺性协同仿真算例,并根据响应量时间历程数据计算了簧载质量加权加速度均方根值和车轮动载均方根值.平顺性分析结果表明该协同仿真方法合理、可靠,满足非线性车辆模型的平顺性时域分析需要.     

Al、Ga离子对ZnO压敏电阻阀片电气性能的调控

为获取高性能氧化锌压敏电阻阀片,研究了采用镓离子、铝离子共同掺杂的氧化锌压敏电阻的电气性能。测试了氧化锌压敏电阻的小电流区以及高场区的伏安特性曲线。在固定的铝离子掺杂浓度下,随着镓离子掺杂浓度的增加,氧化锌压敏电阻的电压梯度以及非线性系数均表现出了先上升后下降的变化趋势,除此之外,泄漏电流表现出了先下降后上升的变化趋势。当硝酸铝和硝酸镓掺杂摩尔分数分别为0.1%和0.72%时,氧化锌压敏电阻可以获取最佳的电气性能,此时压敏电阻表现出了低残压、高非线性系数以及低泄漏电流的特性。该研究有助于装配电气性能优异的氧化锌压敏电阻。     

非线性退化扩散方程解的爆破

考虑一类非线性退化抛物型方程初边值问题,利用特征函数和Jensen不等式,在一定条件下,证得方程的解在有限时刻爆破.     

一类具高阶非线性项的发展方程的准确周期解

本文导出了具高阶非线性项的Lienard方程的准确周期解并从理论上给予了证明,然后利用这些公式得到一大批具高阶非线性项的发展方程的各种Jacobi椭圆函数型的准确周期解,由此避免了一大类非线性发展方程求周期解时求解过程的重复。     

Inorganic/Organic Double‐Network Gels Containing Ionic Liquids

Highly robust ion gels, termed double‐network (DN) ion gels, composed of inorganic/organic interpenetrating networks and a large amount of ionic liquids (ILs), are fabricated. The DN ion gels with an 80 wt% IL content show extraordinarily high mechanical strength: more than 28 MPa of compressive fracture stress. In the DN ion gel preparation, a brittle inorganic network of physically bonded silica nanoparticles and a ductile organic network of polydimethylacrylamide (PDMAAm) are formed in the IL. Because of the different reaction mechanisms of the inorganic/organic networks, the DN ion gels can be formed by an easy and free‐shapeable one‐pot synthesis. They can be prepared in a controllable manner by manipulating the formation order of the inorganic and organic networks via not only multistep but also single‐step processes. When silica particles form a network prior to the PDMAAm network formation, DN ion gels can be prepared. The brittle silica particle network in the DN ion gel, serving as sacrificial bonds, easily ruptures under loading to dissipate energy, while the ductile PDMAAm network maintains the shape of the material by the rubber elasticity. Given the reversible physical bonding between the silica particles, the DN ion gels exhibit a significant degree of self‐recovery by annealing.     

Bad-scenario-set robust scheduling for a job shop to hedge against processing time uncertainty

This paper proposed two robust scheduling formulations in real manufacturing systems based on the concept of bad scenario set to hedge against processing time uncertainty, which is described by discrete scenarios. Two proposed robust scheduling formulations are applied to an uncertain job-shop scheduling problem with the makespan as the performance criterion. The united-scenario neighbourhood (UN) structure is constructed based on bad scenario set for the scenario job-shop scheduling problem. A tabu search (TS) algorithm with the UN structure is developed to solve the proposed robust scheduling problem. An extensive experiment was conducted. The computational results show that the first robust scheduling formulation could be preferred to the second one for the discussed problem. It is also verified that the obtained robust solutions could hedge against the processing time uncertainty through decreasing the number of bad scenarios and the degree of performance degradation on bad scenarios. Moreover, the computational results demonstrate that the developed TS algorithm is competitive for the proposed robust scheduling formulations.     

具有两参数的非线性非局部扰动发展方程奇摄动问题

本文研究了一类具有非线性非局部扰动发展方程的奇摄动问题.利用奇摄动方法,对该问题解的结构在两个小参数相互关联的情形和适当的条件下展开了全面研究.首先,构造了问题的外部解;然后在区域的边界邻域构造局部坐标系,再在该邻域中引入多尺度变量,得到问题解的边界层校正项,另外,通过引入伸长变量构造了初始层校正项;最后,利用不动点定理,证明了问题的解的一致有效的渐近展开式.用上述方法得到的各次近似解,具有便于求解、精度高等特点.     

采用磁流变阻尼器的汽车悬架系统的杂交建模

利用线性回归方法,对磁流变阻尼器阻尼力与速度、加速度间的函数关系作了线性与非线性的区分,采用神经网络对非线性部分进行建模,并结合线性部分构建了磁流变阻尼器的模型。在此基础上,融合汽车悬架的先验知识模型,建立了采用磁流变阻尼器的4自由度1/2车辆半主动悬架系统的杂交模型。最后利用SANTANA 2000型轿车的参数进行仿真,并与基于磁流变阻尼器非线性滞回模型的建模方法作了比较,结果表明:杂交建模方式结构简单、计算量小、模型准确、便于进行系统主要动力学特性的分析。