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基于非线性干扰观测器的无人平台有限时间镇定控制

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北京理工大学学报 2017年第8期37卷 824-829页

作者：华玉龙任华林孙伟郭晓林迟宝山装甲兵工程学院机械工程系北京100072 浙江万里扬股份有限公司浙江金华321025

研究了存在模型不确定性和外界干扰工况下的非完全对称无人平台有限时间镇定控制问题.考虑模型参数矩阵的非对角线元素存在非零项,仅通过一次微分同胚变换即将原模型化为级联系统形式,简化了计算步骤;基于此级联系统借助终端滑模和反步... 详细信息

研究了存在模型不确定性和外界干扰工况下的非完全对称无人平台有限时间镇定控制问题.考虑模型参数矩阵的非对角线元素存在非零项,仅通过一次微分同胚变换即将原模型化为级联系统形式,简化了计算步骤;基于此级联系统借助终端滑模和反步控制方法设计了有限时间收敛控制器,解决了传统反步滑模控制器收敛速度缓慢的问题;通过引入1阶低通滤波器,对镇定控制器结构进行了优化,避免了执行器陷入"饱和";基于非线性干扰观测器对外界干扰及系统不确定性进行平滑估计和补偿,无需明确知道估计误差的上界即有效提高了控制器的鲁棒性.最后基于Lyapunov理论证明了闭环系统具有均方意义稳定性并进行了数值仿真,仿真结果验证了控制器的有效性和鲁棒性.

关键词：非完全对称无人平台有限时间镇定控制全局微分同胚变换终端滑模控制非线性干扰观测器

Dynamical Predictability of Leading Interannual Variability Modes of the Asian-Australian Monsoon in Climate Models

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Advances in Atmospheric Sciences 2023年第11期40卷 1998-2012,I0002,I0003页

作者： lin WANG Hong-Li REN Fang ZHOU Nick DUNSTONE Xiangde XU State Key Laboratory of Severe Weather and Institute of Tibetan Plateau MeteorologyChinese Academy of Meteorological SciencesBeijing 100081China Department of Atmospheric Science School of Environmental StudiesChina University of GeosciencesWuhan 430074China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and TechnologyNanjing 210044China Met Office Hadley Centre FitzRoy RoadExeterDevonEX13PBUnited Kingdom

The dynamical prediction of the Asian-Australian monsoon(AAM)has been an important and long-standing issue in climate *** this study,the predictability of the first two leading modes of the AAM is studied using retrospective prediction datasets from the seasonal forecasting models in four operational centers *** show that the model predictability of the leading AAM modes is sensitive to how they are defined in different seasonal sequences,especially for the second *** first AAM mode,from various seasonal sequences,coincides with the El Niño phase transition in the eastern-central *** second mode,initialized from boreal summer and autumn,leads El Niño by about one year but can exist during the decay phase of El Niño when initialized from boreal winter and *** findings hint that ENSO,as an early signal,is conducive to better performance of model predictions in capturing the spatiotemporal variations of the leading AAM ***,the persistence barrier of ENSO in spring leads to poor forecasting skills of spatial *** multimodel ensemble(MME)mean shows some advantage in capturing the spatiotemporal variations of the AAM modes but does not provide a significant improvement in predicting its temporal features compared to the best individual models in predicting its temporal *** BCC_CSM1.1M shows promising skill in predicting the two AAM indices associated with two leading AAM *** predictability demonstrated in this study is potentially useful for AAM prediction in operational and climate services.

关键词： Asian-Australian monsoon(AAM) leading interannual variability modes El Niño seasonal forecasting models multimodel ensemble(MME)

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星载真实孔径雷达波谱仪的海浪谱反演仿真

电子学报 2010年第12期38卷 2867-2874页

作者：林文明董晓龙周玉驰中国科学院空间科学与应用研究中心北京100190 中国科学院研究生院北京100049

本文概述了星载雷达测量海浪方向谱的原理及相应的系统配置,并介绍一种端到端的系统仿真方法,分析系统在不同配置和海况下的波谱反演性能.仿真结果表明,星载雷达波谱仪能够以较高精度测量有效波高大于2.0m的风浪和中低风速条件下的涌浪... 详细信息

本文概述了星载雷达测量海浪方向谱的原理及相应的系统配置,并介绍一种端到端的系统仿真方法,分析系统在不同配置和海况下的波谱反演性能.仿真结果表明,星载雷达波谱仪能够以较高精度测量有效波高大于2.0m的风浪和中低风速条件下的涌浪(有效波高大于0.8m).最小可检测波长为40m,波长为200m时测量精度优于20m;平均之后波谱测量的方向精度优于20°.同时证明,10°入射角的波束配置优于6°入射角.

关键词：真实孔径雷达波谱仪方向谱调制谱相关系数

Online traffic-aware linked VM placement in cloud data centers

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Science China(Information Sciences) 2020年第7期63卷 182-204页

作者： Liwei lin David S.L.WEI Ruhui MA Jian LI Haibing GUAN Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiao Tong University Department of Computer & Information Sciences Fordham University

In cloud computing, virtual machine(VM) placement plays a crucial role in data center(DC)management, as different ways of VM placement may require different system resources. As Cisco research reveals that virtualization of DC increases traffic within the DC and causes network bandwidth to become scarce resource, recent researches have been focusing on traffic-aware VM placement. However, previous traffic-aware VM placement schemes treat the VM placement as a static process in that they do not take into account the impact of the current placement decision on the subsequent placement. In this paper,we thus propose a novel online traffic-aware VM placement scheme. Our scheme views VM placement as a context-sensitive dynamic process in that the decision of every step of the placement is made aiming at helping the subsequent steps of placement to reduce the required network bandwidth in the long run. In our scheme, we consider not only inter-VM traffic but also the bandwidth constraint of a physical machine(PM) when making a VM placement decision. To realize our objective, we put those VMs with close end time in the same or close proximity PMs so that when the VMs are terminated, one can make enough room for the future arrivals so as to not only minimize the number of active PMs but also reduce networking costs. We conduct extensive simulations to verify the superiority of our scheme in terms of networking costs and energy consumption. Simulation results show that our scheme outperforms improved-best-fit-decreasing(IBFD) scheme, a revised best-fit version that takes inter-VM traffic into account, by 30%–40% on network cost under various scenarios. Our scheme also promises 10%–25% power savings compared with IBFD.

关键词： linked VMs traffic-aware online VM placement cloud data center energy efficient

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曲线轨道钢轨扭转振动频率响应特性研究

振动工程学报 2018年第4期31卷 644-653页

作者：杜林林刘维宁刘卫丰马龙祥北京交通大学土木建筑工程学院隧道与地下工程系北京100044 西南交通大学土木工程学院地下工程系四川成都610031

将曲线轨道视为周期性离散支承结构,根据周期性结构的振动特性,将曲线轨道动力响应的求解问题转化在一个基本元之内进行研究,将固定谐振荷载视为速度为零的移动谐振荷载,通过引入移动谐振荷载作用下曲线轨道钢轨的频域数学模态及广义波... 详细信息

将曲线轨道视为周期性离散支承结构,根据周期性结构的振动特性,将曲线轨道动力响应的求解问题转化在一个基本元之内进行研究,将固定谐振荷载视为速度为零的移动谐振荷载,通过引入移动谐振荷载作用下曲线轨道钢轨的频域数学模态及广义波数,得出曲线轨道钢轨扭转振动频域响应的级数表达。在频域内采用模态叠加法表示钢轨的扭转振动,进而求解得出不同激振频率下钢轨的扭转振动频域响应,得到曲线轨道扭转振动频率响应函数。针对曲线轨道扭转振动频响特性,分析了扣件支点扭转刚度、扭转阻尼系数、扣件支点间距以及曲线半径等因素对频响函数的影响。

关键词：曲线轨道弯扭耦合周期结构频域模态叠加法频响函数

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紧耦合INS/视觉相对位姿测量方法

中国惯性技术学报 2011年第6期19卷 686-691页

作者：王龙董新民张宗麟空军工程大学工程学院西安710038

研究了一种紧耦合INS/视觉相对位姿测量方法在无人机自主空中加油中的应用。该方法直接将特征点的图像坐标作为滤波器输入,避免了求解复杂的非线性位姿方程,尤其是特征点提取不全时,该方法具有较强的鲁棒性。引入相对惯导误差建立了增... 详细信息

研究了一种紧耦合INS/视觉相对位姿测量方法在无人机自主空中加油中的应用。该方法直接将特征点的图像坐标作为滤波器输入,避免了求解复杂的非线性位姿方程,尤其是特征点提取不全时,该方法具有较强的鲁棒性。引入相对惯导误差建立了增广状态模型,根据杆臂效应详细推导了紧、松两种耦合模式的量测方程。采用扩展卡尔曼滤波算法估计误差状态,并校正惯导输出获取精确的相对位姿信息。仿真结果表明,与松耦合模式相比,紧耦合在提高系统实时性的同时可获得更高的测量精度,位置误差小于0.1 m,姿态角误差小于3'。

关键词：紧耦合惯性导航机器视觉相对位姿扩展卡尔曼滤波

对多波次目标直接分配到弹的反导火力规划方法

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系统工程与电子技术 2014年第11期36卷 2206-2212页

作者：李龙跃刘付显赵麟锋空军工程大学防空反导学院陕西西安710051

火力规划是反导力量作战运用的重中之重,对多波次目标的反导火力安排与分配是一个复杂的不确定多约束优化问题。在对反导火力规划问题分析的基础上,给出了弹-目分配时机、模型思路和假设。分拦截任务分配和弹-目分配两步建立了反导火力... 详细信息

火力规划是反导力量作战运用的重中之重,对多波次目标的反导火力安排与分配是一个复杂的不确定多约束优化问题。在对反导火力规划问题分析的基础上,给出了弹-目分配时机、模型思路和假设。分拦截任务分配和弹-目分配两步建立了反导火力规划模型,拦截任务分配中,通过时间段分解将同时需要求解的多个问题转换为多个子时间段的一个问题;弹-目分配中,基于航路捷径、目标落点的不同,拦截弹拦截有利度计算是关键环节。模型突破以往研究目标不考虑时间约束的局限,建立起弹-目-时间对应分配关系,提供一种新的、动态的反导火力规划方法,仿真实例体现了模型较好的工程应用前景。

关键词：反导火力规划弹-目-时间分配时间段分解航路捷径与落点

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关于最大度确定的树的谱半径

华东师范大学学报（自然科学版） 2007年第3期 75-81页

作者：徐芹林祺束金龙华东师范大学数学系上海200062

讨论了点数和最大度均固定的一类树的谱半径,分别给出了这类树的谱半径的上界和下界,并分别刻画了达到上下界的极图。

关键词：树最大度谱半径

Experimental investigation of vibration pretreatment-microwave curing process for carbon fiber reinforced resin matrix composites

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Journal of Central South University 2024年第6期31卷 1838-1855页

作者： ZHANG De-chao ZHAN Li-hua MA Bo-lin YAO Shun-ming GUO Jin-zhan GUAN Cheng-long LIU Shu Light Alloys Research Institute Central South UniversityChangsha 410083China College of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China

The vibration pretreatment-microwave curing process is an efficient,low energy consumption,and high-quality out-of-autoclave curing process for carbon fiber resin matrix *** study aims to investigate the impact of vibration pretreatment temperature on the fiber weight content,microscopic morphology and mechanical properties of the composite laminates by using optical digital microscopy,universal tensile testing machine and thermo-gravimetric ***,the combined mode of Bragg fiber grating sensor and temperature measurement fiber was employed to explore the effect of vibration pretreatment on the strain process during microwave *** study results revealed that the change in vibration pretreatment temperature had a slight impact on the fiber weight content when the vibration acceleration remained *** metallographic and interlaminar strength of the specimen formed at a vibration pretreatment temperature of 80℃ demonstrated a porosity of 0.414% and a 10.69% decrease in interlaminar shear strength compared to autoclave ***,the introduction of the vibration energy field during the microwave curing process led to a significant reduction in residual strain in both the 0°and 90°fiber directions,when the laminate was cooled to 60℃.

关键词： vibration microwave curing porosity interlaminar shear strength thermo-gravimetric analysis curing strain