冲击载荷下磁流变阻尼器结构优化设计

应用于火炮反后坐装置中的磁流变阻尼器工作在高冲击、高速环境下,对磁流变阻尼器的设计指标和性能提出了更高的要求.针对冲击试验中,磁流变阻尼器表现出的阻尼力可调动态范闱的不足,利用Herschel-Bulkley的磁流变液非线性结构特性的平行平板恒流模型,采用多目标规划方法,提出了火炮反后坐装置应用中的磁流变阻尼器优化设计方法.最后分析了磁流变阻尼器磁路设计准则,结合优化设计尺寸,对阻尼器活塞磁场进行了有限元分析.结果表明,磁流变阻尼器阻尼通道处能产生足够大的磁场强度且分布均匀.     

具有输出时延的网络控制系统故障检测

考虑一类具有长时延的网络控制系统,假定其传感器到控制器之间存在输出时延,对其进行故障检测研究.建立具有时延补偿功能的故障观测器,得到状态估计误差方程.基于离散切换系统理论,将观测器系统的稳定条件归结为一个线性矩阵不等式.当系统正常时,只要给定的矩阵不等式条件成立,该观测器系统就是渐近稳定的.当系统发生故障时,观测器残差能够迅速发生跳变,从而检测出故障的发生.仿真示例验证了方法的有效性.     

A piecewise analysis method to stability analysis of linear continuous/discrete systems with time‐varying delay

The delay‐dependent stability problem of linear continuous/discrete systems with time‐varying delay is investigated based on a piecewise analysis method (PAM). In the method, the variation interval of the time delay is firstly divided into several subintervals. By checking the variation of the Lyapunov functional in every subinterval, some new delay‐dependent stability criteria are derived. Several numerical examples show that our method can lead to much less conservative results than those in the existing references. Moreover, when the number of the divided subintervals increases, the corresponding criteria can provide an improvement on the results. Copyright © 2008 John Wiley & Sons, Ltd.     

基于条件李亚普诺夫指数的混沌系统的脉冲同步研究

基于条件李亚普诺夫指数,对混沌系统的脉冲同步形式和同步范围进行了研究,突破了传统的基本假设．计算机仿真证明了该方法的有效性和正确性．此外,作为该方法的重要基础,本文给出脉冲同步系统的条件李亚普诺夫指数计算方法．     

用过期“双迫”发射药改制射钉枪药的研究

文章分析了将过期“双迫”药改制成射钉枪药的可行性．实验表明,改制可采用球形药工艺,制品能满足射钉枪的使用要求．     

Minimizing Energy Barrier in Intermediate Connection Layer for Monolithic Tandem WPeLEDs with Wide Color Gamut

Perovskite light-emitting diodes (PeLEDs) show promising prospects in the wide color gamut display owing to their ultra-narrow full width at half maximum (FWHM). However, up to now, all perovskite white LEDs integrated by standard red, green, and blue perovskite emitters, namely, monolithic white PeLEDs (WPeLEDs), have been rarely reported, owing to facing some issues, e.g., solvent incompatibility in solution technique, ion exchange, and energy transfer between different emission centers. Herein, centered on these issues, an optimal intermediate connection layer (ICL) of Po-T2T/LiF/Ag/HAT-CN/MoO₃ is adopted to successfully develop monolithic tandem multicolor PeLEDs and WPeLEDs for the first time. The multicolor PeLEDs can achieve the best external quantum efficiency of 1.8% and the highest luminance of 4844 cd m⁻². Besides, the red/green/blue (R/G/B) monolithic tandem WPeLED shows a standard white International Commission on Illumination coordinate of (0.33, 0.33) and achieves an extremely wide color gamut reaching  National Television Standards Committee of 130%. This study is the first to realize the standard R/G/B co-electroluminescence in a monolithic perovskite device and offers a feasible strategy for developing wide-color gamut perovskite displays.     

Blind omnidirectional image quality assessment with representative features and viewport oriented statistical features

With the development of information technologies, various types of streaming images are generated, such as videos, graphics, Virtual Reality (VR)/omnidirectional images (OIs), etc. Among them, the OIs usually have a broader view and a higher resolution, which provides human an immersive visual experience in a head-mounted display. However, the current image quality assessment works cannot achieve good performance without considering representative human visual features and visual viewing characteristics of OIs, which limited OIs’ further development. Motivated by the above problem, this work proposes a blind omnidirectional image quality assessment (BOIQA) model based on representative features and viewport oriented statistical features. Specifically, we apply the local binary pattern operator to encoder the cross-channel color information, and apply the weighted LBP to extract the structural features. Then the local natural scene statistics (NSS) features are extracted by using the viewport sampling to boost the performance. Finally, we apply support vector regression to predict the OIs’ quality score, and experimental results on CVIQD2018 and OIQA2018 Databases prove that the proposed model achieves better performance than state-of-the-art OIQA models.     

<Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> fault detection for linear singular systems with time-varying delay

This paper deals with the problem of H _∞ fault detection for a kind of linear singular systems with time-varying delay. A generalized form of observer-based fault detection filter (FDF) is first used as a residual generator. Then the design of H _∞-FDF is formulated in the framework of H _∞ filtering. By applying Lyapunov-Kravoskii function approach, delay-dependent conditions on the existence of the H _∞-FDF, which ensure asymptotic stability and a prescribed H _∞ performance level, are derived. With the aid of a cone complementarity linearization technique, an iterative algorithm is proposed to calculate the parameter matrices of the H _∞-FDF in terms of linear matrix inequalities. A numerical example is given to illustrate the effectiveness of the proposed algorithm.     

一种减少测距误差的传感器网络定位算法

接收信号强度(RSSI)常被作为无线传感器网络定位算法的测距技术,通常,获取的RSSI信号序列中同时存在随机误差和粗差两种误差,利用以往常用的算法都难以消除混合误差对RSSI测量统计数据的影响;在分析两种误差特征的基础上,提出了一种基于统计中值的加权定位算法,算法在去除粗差的基础上,能在一定程度上平滑了随机误差,算法不仅提高了定位的精度,同时提高了节点的覆盖率;理论分析和仿真结果都表明算法具有较高的定位精度和覆盖率,最优情况下定位精度较原先算法能够提高6.99%,而不可定位节点比例下降8.05%。