关于无穷维耗散非线性动力系统全局吸引子的存在性

证明了一类非线性发展型方程的全局吸引子的存在性，作为这个结果的应用，考虑了带有弱导数项的非线性反应扩散方程，并证明了该方程具有全局吸引子．由于方程不具有正则性，需要采用新的方法．     

关于u~5-Klein Gordon方程H''''强解序列的振荡与集中

对ｕ５－ＫｌｅｉｎＧｏｒｄｏｎ方程，构造了一列具有紧支集的Ｈ强解序列．它在极限过程中，相对具有同样初值的线性波动方程，会产生新的振荡和集中．这种现象对非线性项的指数Ｐ小于５的半线性波动方程是不会出现的     

快速液体衰减反转回复序列技术在脑梗死诊？…

目的探讨快速液体衰减反转回复序列(FASTFLAIR)技术原理及其对脑梗死的诊断价 值。方法对71例脑梗死患者进行FASTFLAIR序列及常规快速自旋回波(FSE)序列扫描，FAST FLAIR序列与FSE序列T2加权像(丁2WI)比较。结果在71例脑梗死病例中，FASTFLAIR像显示病 灶210个，T2WI像显示150个。FASTFLAIR像显示病灶较T2WI像清楚明确。结论FASTFLAIR序 列对脑梗死病灶的显示优于FSET2加权序列，特别是对脑表面或脑室周围病灶的显示，应作为常 规FSE序列的重要补充。     

汽车半主动磁流变悬架的自适应相对控制研究

为了提高汽车的运行平顺性和操纵稳定性,以磁流变减振器为控制对象,提出了采用自适应神经网络相对控制方法的半主动悬架系统。在试验测试和理论分析的基础上,通过数据拟合得到磁流变减振器阻尼力的非线性Bingham模型,建立了基于该磁流变减振器的半主动悬架模型,并用该模型进行了自适应神经网络相对控制方法的研究。以模拟道路谱作为输入,以车身俯仰角加速度和车辆悬架前、后侧弹簧的垂向变形量之差作为控制量,把车身质心垂向加速度、前后悬架动行程作为评价指标来进行仿真研究。仿真结果表明,设计的半主动悬架与被动悬架相比,其平顺性与稳定性均得到了良好的改善,且对运行工况的改变有一定的适应性,对系统参数摄动也具有很强的鲁棒性。     

Data based model free hysteresis identification for a nonlinear structure

In the last two decades, the damage detection for civil engineering structures has been widely treated as a modal analysis problem and most of the currently available vibration-based system identification approaches are based on modal parameters, namely the natural frequencies, mode shapes and damping ratios, and/or their derivations, which are suitable for linear systems. Nonlinearity is generic in engineering structures. For example, the initiation and development of cracks in civil engineering structures as typical structural damages are nonlinear process. One of the major challenges in damage detection, early warning and damage prognosis is to obtain reasonably accurate identification of nonlinear performance such as hysteresis which is the direct indicator of damage initiation and development under dynamic excitations. In this study, a general data-based identification approach for hysteretic performance in form of nonlinear restoring force using structural dynamic responses and complete and incomplete excitation measurement time series was proposed and validated with a 4-story frame structure equipped with smart devices of magneto-rheological (MR) damper to simulate nonlinear performance. Firstly, as an optimization method, the least-squares technique was employed to identify the system matrices of an equivalent linear system of the nonlinear structure model basing on the excitation force and the corresponding vibration measurements with impact test when complete and incomplete excitations; and secondly, the nonlinear restoring force of the structure was identified and compared with the test measurements finally. Results show that the proposed data-based approach is capable of identifying the nonlinear behavior of engineering structures and can be employed to evaluate the damage initiation and development of different structure under dynamic loads.     

Vibration Control of Jacket Platforms with Magnetorheological Damper and Experimental Validation

Magnetorheological (MR) dampers have been proposed to control the vibration of offshore platforms in this paper. The semi-active control strategy based on fuzzy control algorithm was adopted to determine the optimal output control force based on the responses of jacket platforms. A typical jacket platform in Mexico Gulf was selected as the numerical example to investigate the effectiveness of the proposed control method. Furthermore, a model experiment was performed to validate the results of the numerical simulation. The experimental model of the jacket platform was designed based on dynamical similarity criterion by the scale of 1:50. Both of the numerical and experimental results show that the semi-active control system with the MR damper can reduce vibrations of jacket platforms effectively and at the same time the control effect is stable.     

DT-MRI数据集的一种拓扑可视化方法

引入了扩散张量磁共振数据集的拓扑可视化方法.将扩散张量磁共振薄层的3D扩散张量投影为2D,仅考虑平面内的扩散.对这个2D张量场进行拓扑分析,提取出对应的拓扑结构.矢冠轴位上的胼胝体、丘脑等脑组织拓扑结果表明,拓扑方法可以精确且综合地表现出脑组织的根本结构.与简单的纤维跟踪相比,基于拓扑的可视化结果更加清晰,用简单的点和线表示扩散张量场的复杂结构,能够突出场的连通性.     

多参数广义Wiener过程像集的一致Hausdorff维数

得到了多参数广义Wiener过程像集的一致Hausdorff维数在一定条件下,a.s.()E∈B(R N +)有(2)/(β)dimE≤dim( AW～U (E))≤(2)/(α)dimE     

火箭弹MR/GPS制导系统应用仿真

研究MR／GPS制导方案在实行过程中可能遇到的问题。针对制导信号较弱、附加干扰噪声大的特点，运用小波强制滤波的方法，设计了小波滤波器；提出基于MR／GPS系统的弹体滚转测量方案并进行了仿真；对弹道控制的脉冲点火策略进行了研究。仿真结果表明：小波滤波的效果较好、有用信号能量损失小；基于MR的滚转测量方案易于实现，但需进行必要的修正。     

导管架式海洋平台模型结构磁流变阻尼隔震数值分析

对渤海JZ20-2MUQ导管架式海洋平台1：10比例模型结构进行数值分析．首先，对模型结构进行了参数影响分析，确定了隔震橡胶垫的基本参数；然后，根据阻尼器性能试验结果，确定了磁流变阻尼器的基本设计参数；最后，采用多种地震作用对模型结构进行了时程分析．结果表明：磁流变阻尼隔震控制方案有效地减少了导管架结构的振动、甲板层的加速度和隔震层的层间变形．为模型结构的试验研究提供了合理的设计参数，并验证了方案的可行性．