不确定奇异系统的时滞相关鲁棒H∞滤波器设计

为了设计出全阶的滤波器,同时使得滤波误差动态系统是正则的、无脉冲的,并且满足一定的H_∞性能指标,研究了连续奇异系统的全阶H_∞滤波器的设计问题.利用Lyapunov-Krasovskii泛函及二次型的积分不等式方法获得了滤波误差动态系统的H_∞性能时滞相关的判据,给出了奇异系统的鲁棒H_∞滤波器存在的时滞依赖的充分条件.最后的数值例子说明了该方法的有效性.     

欺骗攻击下一类神经网络的自适应事件触发H∞滤波

本文主要研究了在欺骗攻击下的离散时间神经网络的H_∞滤波器设计问题.考虑到被控系统和滤波器在一个易受外部网络攻击且带宽有限的共享通信网络上进行信息交换,本文提出了自适应事件触发机制来减轻数据传输的通信负担.此外,由于通信网络的开放性和互通互联,通过共享通信网络传输到滤波器的实际输入信息可能会被攻击者注入的虚假信息所改变.在此基础上,利用构造Lyapunov-Krasovskii泛函、线性矩阵不等式等处理技术,本文给出了滤波误差系统渐近稳定的充分条件,并且设计了满足预设性能的H_∞滤波器,最后通过一个仿真实例验证了所提方法的有效性.     

具有遗忘时滞的静态神经网络的H∞状态估计

本文研究了具有遗忘时滞的静态神经网络的H_∞状态估计问题.首先降低了时变时滞可微的条件,然后通过构造合适的Lyapunov-Krasovskii泛函,设计保H_∞性能的状态估计器,使得误差系统实现全局渐近稳定.最后,借助Matlab中线性矩阵不等式工具箱进行数值仿真,验证了结论的有效性.     

模糊多智能体系统的H∞一致跟踪控制

本文研究非线性多智能体系统在有向拓扑下的领导跟随H_∞一致性问题.首先,提出一种新的多项式模糊建模方法来描述由领导者与跟随者构建的偏差动态系统.然后,设计一致控制协议使跟随者渐近跟踪领导者的轨迹.基于多项式李雅普诺夫函数技术,提出松弛的渐近一致的充分条件并确保存在外界干扰时多智能体系统具有H_∞抑制性能.将导出的条件转化为平方和形式并能够进行数值求解.最后,给出一个实例来验证所提出的一致控制协议的有效性.     

具有异步控制器的离散马尔可夫跳变Lur'e系统的稳定性和l2增益性能分析

本文研究了一类具有异步控制器的离散马尔可夫Lur''e跳变系统的稳定性及l₂增益性能.通过引入隐马尔可夫模型（HHM）来描述所设计的控制器和原始系统之间出现的异步现象.利用线性矩阵不等式（LMI）方法分析了闭环系统的稳定性和l₂增益性能.然后提出了一个充分条件使得闭环系统随机稳定,并使得从扰动到系统输出的l₂增益达到最小.同时,通过求解给定条件来设计一个由线性状态反馈和扇形有界非线性输出反馈组成的异步控制器.最后,给出了一个数值仿真例子来验证所提方法的有效性.     

含变时滞输入的挠性航天器姿态复合控制

对含变时滞输入的挠性航天器姿态复合控制问题进行了研究,主要是通过设计一个时滞依赖的H_∞控制和干扰观测器（DOBC）相结合的复合分层控制结构,实现姿态角和姿态角速度的稳定控制.本文所提方法的优势为：1）对振动引起的干扰进行精确补偿,减少了干扰对控制效果的影响;2）设计了时滞依赖的状态控制器,降低了时滞对姿态的影响;3）在泛函求解过程中引入了时滞积分不等式分解系数,从而降低了设计的保守性.最后,通过数值仿真验证了本文设计的控制方法的有效性,并分析了时滞量及时滞积分不等式分解系数对闭环系统性能的影响.     

欺骗攻击环境下带有传感器故障的大规模电网分布式状态估计

本文研究了欺骗攻击环境下带有传感器故障的大规模电网分布式状态估计问题.通过引入拓扑关系来描述分布式传感器节点之间的相互关系,使用随机Bernoulli序列描述欺骗攻击模型及其随机特性.基于Lyapunov方法证明了带有传感器故障的系统在遭受欺骗攻击环境下的均方稳定及H_∞稳定的充分条件,并基于LMI设计了满足H_∞性能指标的分布式状态估计器.最后通过数值仿真验证了所设计估计器的有效性.     

顶点Pk覆盖问题的研究综述

顶点覆盖问题是经典的NP完全问题,在排序、计算机网络等现实生活中有许多的应用.近几年来,许多研究者开始探究它的推广形式——顶点P_k覆盖（VCP_k）问题,即寻找一个顶点子集,从拓扑结构图中删除后使得剩下的顶点导出的子图不包含P_k路,其中P_k是指包含k个顶点的路.本文简单介绍了VCP_k问题的应用背景,归纳了它在近似算法、精确算法、参数化算法3个方面的主要研究进展,并分析了一些主要的方法和技巧.在此基础上,对VCP_k问题及其相关问题的研究前景进行了展望.     

一次强降水风暴回波合并前后双偏振特征分析

基于济南S波段双偏振多普勒天气雷达探测数据,结合卫星、探空和地面实况资料,对2020年8月6日发生在山东曲阜一带的强降水风暴合并前后双偏振参量特征和微物理特征进行分析。结果表明:(1)云带之间产生多次合并,合并后风暴加强发展,产生较大的分钟降水量和累计降水量。(2)新生单体最典型的双偏振特征是具有大的Z_DR和CC,以少许液态粒子为主;新生单体迅速发展过程中上升气流强度明显加强,出现明显的K_DP柱和Z_DR柱,液态粒子浓度明显增大并出现偏大的液态粒子。(3)合并后发展的主要特征是,风暴顶高、强回波区顶高和K_DP柱明显增高,-10℃层高度以下,特别是在风暴底层K_DP值明显增大。(4)合并之后风暴发展最典型的微物理特征是,-10℃层高度之下液态雨滴粒子浓度迅速增大,-10℃层高度之上冰晶或霰粒子层的厚度明显增大。发展旺盛的风暴中、低层有丰富的液态水,风暴高层含有丰富的冰相粒子,从而导致风暴产生高强度降水。     

马尔可夫切换的汽车悬架系统的事件触发H∞滤波

针对具有马尔可夫切换信道的两自由度（2-DOF） 四分之一汽车悬架系统,研究了事件触发 H_∞ 滤波问题.首先,信道切换由马尔可夫链控制;其次,考虑到事件触发的通信方案,由于有限的网络带宽,产生信号量化和随机丢包问题;然后,采用马尔可夫线性跳变系统模型来表示整个滤波网络系统.利用Lyapunov泛函和线性矩阵不等式方法将事件触发 H_∞ 滤波问题转化为凸优化问题,从而设计了切换信道相关的滤波器,使得滤波误差系统在均方意义上是指数稳定的并达到期望的性能水平.最后,通过仿真实例验证了所提出的设计方法的有效性.     

具有DoS攻击的网络控制系统事件触发安全控制

本文主要研究在随机出现的双通道DoS攻击下的网络控制系统基于事件触发的安全控制问题.首先,提出了一个具有补偿策略的DoS攻击模型,且此攻击模型应用于网络系统的传感器-控制器通道和控制器-执行器通道;其次,为了降低通信负担,提出事件触发机制,通过定义一个触发条件,当触发条件满足时,才进行信息传递;最终得到闭环控制系统模型.根据最优控制理论和线性矩阵不等式技术,得到闭环系统以一定概率输入到状态稳定的充分条件,进一步通过一系列矩阵变换处理技巧,通过解线性矩阵不等式方程组得到控制器参数.最后,通过计算机仿真验证了该控制器设计的有效性.     

Water erosion control

Under natural conditions, balanced ecological systems develop in which the soil is protected by a cover of different plants. When man modifies the environment, in his attempts to produce more food, fiber and fuel, the ecological system is changed.This often results in the soil being exposed to the processes of accelerated water erosion. In this way, millions of hectares of land, particularly in the semi arid areas are now eroding.This paper stresses that the most important principle in controlling water erosion is to develop a new balanced system which is not only productive but which is also stable.Water erosion control schemes should therefore be based on the selection and introduction of correct land use.Examples are given of the types of measures that may be needed for cultivated, grazing and forestry lands.In some cases, a change in land use may also have to be supported by the construction of physical conservation measures. Some common examples of such measures are briefly described.     

Wind erosion control

Wind erosion is a serious problem in many parts of the world. It physically removes from the field the most fertile portion of the soil, pollutes the air, fills road ditches, reduces seedling survival and growth, lowers the marketability of many vegetable crops, and creates new desert landforms and landscapes. It is generally worse in arid and semi-arid than in subhumid climates.A wind erosion equation was developed as a result of many investigations on the factors influencing wind erosion. It is a useful guide to the principles of wind erosion control. The functional relationship is expressed as E = % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeyOKbykaaa!37B2!\[f\](I,K,C,L,V), where E is potential average annual soil loss per unit area, I is a soil erodibility index, K is a soil ridge roughness factor, C is a climatic factor, L is the unsheltered median travel distance of wind across a field, and V is an equivalent quantity of vegetative cover.Principles suggested by the wind erosion equation for controlling wind include: stabilizing erodible surface with various materials; producing a rough, cloddy surface; reducing field width or the distance wind travels in crossing an unprotected field with barriers and strip crops; and establishing and maintaining sufficient vegetative cover. This last item is sometimes referred to as the cardinal rule for controlling wind erosion.     

Emissions control and reduction

A brief review of the information available on technological means for reducing anthropogenic emissions of greenhouse gases is provided. No assessment of economic or institutional difficulties for their implementation is attempted. A few cost figures are quoted where available, usually at the single-unit, microeconomic level, and further aggregation of the data is required to estimate global costs. Considerable additional analysis is required to do the latter, since simple summation of micro-level figures will in general not correctly yield macro level costs. It follows that no conclusions can be drawn from the information provided in this paper as to the preferred, most effective strategies for abating emission growths. The review should be viewed as providing a snap-shot picture of the data available as of today that is needed as input to an analysis of means and costs for achieving global scale reduction in emissions levels.     

Human control of climate change

The use of analogies and repeated feedback might help people learn about the dynamics of climate change. In this paper, we study the influence of repeated feedback on the control of a carbon-dioxide (CO₂) concentration to a goal level in a Dynamic Climate Change Simulator (DCCS) using the “bathtub” analogy. DCCS is a simplification of the complex climate system into its essential elements: CO₂ concentration (stock); man-made CO₂ emissions (inflow); and natural CO₂ removal or absorption in the atmosphere (outflow). In a laboratory experiment involving DCCS, we manipulated feedback delays in two ways: the frequency of emission decisions and the rate of CO₂ absorption from the atmosphere (climate dynamics). Our results revealed that participants’ ability to control the CO₂ concentration generally remained poor even in conditions where they were allowed to revise their emission decisions frequently (i.e., every 2?years) and where the climate dynamics were rapid (i.e., 1.6% of CO₂ concentration was removed every year). Participants’ control of the concentration only improved with repeated feedback in conditions of lesser feedback delay. Moreover, the delay due to climate dynamics had a greater effect on participants’ control than the delay due to emission decisions frequency. We provide future research directions and highlight the potential of using simulations like DCCS to help people learn about dynamics of Earth’s climate.     

气象资料的质量控制

气象资料的质量受到各种非气候因素的影响,需要采用各种传统和非传统的方法进行检查、修正,进行质量控制,以确保提供应用的资料应该符合各种要求。     

气象资料的质量控制

气象资料的质量受到各种非气候因素的影响,需要采用各种传统和非传统的方法进行检查、修正,进行质量控制,以确保提供应用的资料应该符合各种要求.     

Quality control algorithms for rainfall measurements

One of the basic requirements for a scientific use of rain data from raingauges, ground and space radars is data quality control. Rain data could be used more intensively in many fields of activity (meteorology, hydrology, etc.), if the achievable data quality could be improved. This depends on the available data quality delivered by the measuring devices and the data quality enhancement procedures. To get an overview of the existing algorithms a literature review and literature pool have been produced. The diverse algorithms have been evaluated to meet VOLTAIRE objectives and sorted in different groups. To test the chosen algorithms an algorithm pool has been established, where the software is collected. A large part of this work presented here is implemented in the scope of the EU-project VOLTAIRE (Validation of multisensors precipitation fields and numerical modeling in Mediterranean test sites).     

多模式智能路灯控制系统

使用AT89S52单片机作为主控芯片,设计了一种多模式智能路灯控制系统,该系统能够根据道路、巷口或定时应用3种情况进行工作模式选择,并根据环境光亮度决定是否启动所设定的工作模式.巷口工作模式时,系统通过红外传感器检测道路上有汽车或行人通过时,将识别信号送入单片机,由单片机控制交通灯开启;道路工作模式时,路灯处于开启状态,以保障行人畅行;定时模式时,通过DS1302定时模块,可以设定路灯的开关时间.此外,该系统还具有自动故障检测功能,功能全面,有较强的实用价值.     

一种领队车输入未知的多车辆纵向协作控制方法

本文考虑了领队车控制输入未知的情况,提出一种多车辆纵向协作控制方法.首先,通过采用精确反馈线性化技术,得到了线性的车辆的动力学模型.然后,采用双向领队跟随通信策略,基于邻居车辆的状态信息,为每辆跟随车设计分布式控制律.考虑在领队车输入有界的情况下,提出了一种有效的多车辆协作控制算法,能够保证多车辆系统以最大的收敛速率达到内部稳定.最后,仿真结果展示了所提出控制器设计算法的有效性和优越性.