基于两级模糊控制的交叉路口多相位控制

用模糊控制方法对交叉路口的交通信号进行控制,提出一种面向城市交叉路口的交通信号两级模糊控制系统.该系统能够分散处理交通信息参数,有效减少模糊规则数,易于提取模糊规则,实现相位顺序、绿信比和周期均随着交通状况的变化而自适应变化;并利用混沌优化对模糊控制器的隶属度函数进行优化搜索,从而提高交叉路口的通行效率,减少车辆的延误...     

基于Smith预估模糊PID复合控制器的研究

针对空调房间温度被控对象的大滞后大惯性,本文提出一种预估并联型模糊PID复合控制策略。根据偏差大小及时调整模糊和PID控制的比例,利用Smith预估器进行时间补偿控制,同时在模糊控制器上并联一个积分器以消除稳态误差。在模型匹配和失配情况下进行仿真研究,结果表明：该控制器不仅具有鲁棒性好、控制精度高以及响应速度快的特点,尤其在模型失配时具有良好的稳定性,而且对于大时滞系统是一种实用而简便的控制方法。     

欠驱动三连杆机器人的混杂控制方法

针对第二关节为被动关节的欠驱动三连杆机器人,提出一种混杂控制方法．欠驱动三连杆机器人的运动空间分为3个阶段：退化阶段、摇起阶段和平衡阶段．首先,在退化阶段,对第三关节构造Lyapunov函数,并针对此函数设计控制律使其连杆相对于前一连杆自然伸展,使系统退化为类Pendubot机器人;同时基于能量不断增加的思想设计第一关节控制律,以节省后阶段的能量控制时间．其次,在摇起阶段,保持第三关节控制律形式不变;通过仅控制系统能量和同时控制系统能量、角速度两种方法设计第一关节控制律,使系统进入平衡区．最后,对退化后的系统采用线性控制将其稳定在竖直向上不稳定平衡点上．数值仿真结果表明文中所提方法具有控制时间短,所需力矩小等优点．     

基于输出时滞方法的采样数据系统故障估计

从时滞系统角度率先研究了一类非均匀采样数据系统的故障估计问题.首先,基于输出时滞方法将采样数据系统建模成具有时变时滞输出的连续时间系统;然后,通过分析自适应诊断观测器不再适用于此类连续时滞系统的原因,提出了一种能够保证估计误差指数收敛的增广故障估计滤波器设计新方法;并进一步研究了具有噪声干扰的采样数据系统的时变故障估计问题;最后,通过对某型飞控系统的仿真实验结果验证了所提方法的有效性.     

具有双控制输入通道高阶不确定非线性系统控制设计

本文研究了一类高阶不确定非线性系统的全局渐近稳定控制设计问题.不同于现有结果,本文所研究的高阶非线性系统具有两个控制输入通道,即控制输入直接作用于两个一维子系统.这导致已有的控制设计方法不能或难以用来解决该类控制设计问题,因此,寻求新的控制设计方法,用以解决多控制输入通道高阶非线性系统的控制设计问题,是一个很有意义的研究课题.本文首先引入一个有效的反馈变换,从而在非线性系统满足适当假设条件下,成功地将该类系统的控制设计问题转化为规范的单控制输入通道情况下的控制设计问题.进而借助于已有结果,特别是增加幂次积分方法,给出所研究非线性系统的全局渐近稳定控制器的设计方法.尽管本文所研究的系统是具有多控制输入通道高阶非线性系统的特殊情况,所得结果具有一定的局限性,但对更一般情况具有借鉴和指导作用.最后,仿真算例验证了本文理论结果的有效性.     

A generalized regression model based on hybrid empirical mode decomposition and support vector regression with back-propagation neural network for mid-short-term load forecasting

Since load forecasting plays a decisive role in the safe and stable operation of power systems, it is particularly important to explore forecasting methods accurately. In this article, the hybrid empirical mode decomposition (EMD) and support vector regression (SVR) with back-propagation neural network (BPNN), namely the EMDHR-SVR-BPNN model, is proposed. Information theory is mainly used to solve the data tendency problem, and the EMD method is used to solve the data volatility problem. There is no interaction between these two methods; thus these two models can complement each other through generalized regression of orthogonal decomposition. Taking the load data from the New South Wales (NSW, Australia) market as an example, the obtained simulation results are compared with other models. It is concluded that the proposed EMDHR-SVR-BPNN model not only improves the forecasting accuracy but also has good fitting ability. It can reflect the changing tendency of data in a timely manner, providing a strong basis for the electricity generation of the power sector in the future, thus reducing electricity waste. The proposed EMDHR-SVR-BPNN model has potential for employment in mid-short term load forecasting.     

月球轨道器交会对接同波束VLBI测量差分相时延实时解算

同波束VLBI技术是解决月球轨道交会对接地面高精度引导的重要手段．传统的多频点同波束VLBI实时解算算法成功解算差分相位整周模糊度的概率较低,而事后统计修正求解整周模糊度的算法存在较大的时间滞后,从而直接影响月球轨道交会对接两个航天器地面定轨、定位的精度以及实时性．在此背景下,本文研究了应用于月球交会对接条件下的同波束VLBI差分相时延实时解算算法．首先给出了多频点同波束VLBI解算差分相时延及整周模糊度的原理,根据差分相关相位整周模糊和差分相时延实时及事后解算结果,对整周模糊度产生的原因进行分析通过求解精确差分群时延值、采用匹配搜索算法以及差分相位连接条件对传统实时解算算法进行改进,提出一种新的差分相时延实时解算算法．利用SELENE同波束VLBI观测数据进行实时解算．结果表明该算法成功解算模糊度的准确度达到95．49％,相对于传统解算算法准确度提高了5．45％．     

Claims provisions in liability insurance

The settlement delay for very large claims in liability insurance may extend to quite a few years; a delay often years in automobile third-party liability is by no means an exception. The companies consequently have to set aside huge amounts as provisions for outstanding claims. As the total provision may attain 100 times the underwriting profit, an underestimation of this provision of a few per cent could mean short-term bankruptcy for the company. A precise forecast of those outstanding liabilities is therefore of crucial importance Owing to the special nature of the information set (a triangular array of cumulative payments, called the‘run-off triangle’), actuaries have in the past neglected the time series analysis approach and devised their own forecasting models. Those methods are reviewed, and illustrated by a real-life example. Two new autoregressive methods are proposed.     

可移动可弯曲输送机转向油缸控制方法研究

以可移动可弯曲输送机为研究对象,对输送机转弯过程中油缸的控制方法进行探讨。建立整机虚拟样机后,依次记录牵引车转弯角度;计算牵引车轨迹;计算各转向油缸对应伸出时间与位移;控制器控制辅助转向;最后完成轨迹跟踪。仿真分析证明该控制方法正确可行。     

A semiparametric method for predicting bankruptcy

Bankruptcy prediction methods based on a semiparametric logit model are proposed for simple random (prospective) and case–control (choice‐based; retrospective) data. The unknown parameters and prediction probabilities in the model are estimated by the local likelihood approach, and the resulting estimators are analyzed through their asymptotic biases and variances. The semiparametric bankruptcy prediction methods using these two types of data are shown to be essentially equivalent. Thus our proposed prediction model can be directly applied to data sampled from the two important designs. One real data example and simulations confirm that our prediction method is more powerful than alternatives, in the sense of yielding smaller out‐of‐sample error rates. Copyright © 2007 John Wiley & Sons, Ltd.     

非线性随机动力学与控制研究进展及展望

随机动力学系用概率与统计方法研究自然界、工程及社会中各种随机动力学过程与现象。经一个世纪的发展，非线性随机动力学与控制已有相当的理论方法，主要是扩散过程理论方法。本文概述该理论方法，特别是作者提出与发展的非线性随机动力学与控制的Hamilton理论体系框架。最后建议各领域随机动力学与控制研究者进行跨学科的合作研究。     

弹道中段目标回波平动补偿与微多普勒提取

该文针对弹道目标回波微多普勒过大或过小时平动补偿和微多普勒提取问题,提出了一种时域处理方法.该方法通过多级延迟共轭相乘处理实现平动补偿,通过调整延迟时间实现微多普勒缩放,并根据信号能量差异使用Hough变换进行各信号分量的逐次分离和微多普勒的逐次提取.理论分析和仿真实验均表明:本文方法可以有效进行多分量弹道目标复合运动回波信号平动补偿和微多普勒提取,显著提高雷达探测微动结构的能力.     

基于形式化测试的实时系统变更后安全性验证

变更后系统实现的安全性验证是安全攸关系统维护过程中必不可少的环节,也是其面临的主要挑战之一.软件模型检测和程序验证是目前常用的作用于代码层面的自动化安全性验证技术.本文站在系统行为角度,基于形式化方法,提出了一种将变更后系统实现的安全性验证问题归结为一致性测试的方法,尝试通过自动生成的一致性测试用例在系统行为级别上判定系统实现是否安全.为此,首先以时间输入输出自动机及其语义模型为基础,构建了该方法的证明体系,证明了该方法的正确性;其次,建立了变更后系统实现安全性验证的回归测试生成框架.相对于其它实时系统测试方法,这种测试方法不仅可以发现实时系统中常规的不一致性缺陷,而且为变更后系统实现在运行时是否满足指定的安全性属性提供了依据.最后,以轨道交通系统中的列车自动防护功能的变更情景为案例研究,说明了方法的具体应用.     

Statistical surveillance of cyclical processes with application to turns in business cycles

On‐line monitoring of cyclical processes is studied. An important application is early prediction of the next turn in business cycles by an alarm for a turn in a leading index. Three likelihood‐based methods for detection of a turn are compared in detail. One of the methods is based on a hidden Markov model. The two others are based on the theory of statistical surveillance. One of these is free from parametric assumptions of the curve. Evaluations are made of the effect of different specifications of the curve and the transitions. The methods are made comparable by alarm limits, which give the same median time to the first false alarm, but also other approaches for comparability are discussed. Results are given on the expected delay time to a correct alarm, the probability of detection of a turning point within a specified time, and the predictive value of an alarm. Copyright © 2005 John Wiley & Sons, Ltd.     

Subset threshold autoregression

We develop in this paper an efficient way to select the best subset threshold autoregressive model. The proposed method uses a stochastic search idea. Differing from most conventional approaches, our method does not require us to fix the delay or the threshold parameters in advance. By adopting the Markov chain Monte Carlo techniques, we can identify the best subset model from a very large of number of possible models, and at the same time estimate the unknown parameters. A simulation experiment shows that the method is very effective. In its application to the US unemployment rate, the stochastic search method successfully selects lag one as the time delay and five best models from more than 4000 choices. Copyright © 2003 John Wiley & Sons, Ltd.     

GPS连续运行参考站网络分析及网络参数估计

本文分析了各种构网方式对网络模糊度解算效率的影响;阐述了最优双差观测值和观测方程的双差映射生成方法;本文在考虑网络参数的各种相关性的基础上,建立了整网卡尔曼滤波方程来整体估计网络参数,并使用LAMBDA方法解算具有奇异方差阵的模糊度。使用成都GPS综合服务网的子网数据验证了该模糊度算法,使用该网的实时数据计算了天顶对流层延迟网络参数,并与Gamit估值进行了对比。     

Stochastic stability of quasi-integrable Hamiltonian systems with time delay by using Lyapunov function method

The asymptotic Lyapunov stability of one quasi-integrable Hamiltonian system with time-delayed feedback control is studied by using Lyapunov functions and stochastic averaging method. First, a quasi-integrable Hamiltonian system with time-delayed feedback control subjected to Gaussian white noise excitation is approximated by a quasi-integrable Hamiltonian system without time delay. Then, stochastic averaging method for quasi-integrable Hamiltonian system is used to reduce the dimension of the original syst...     

Modeling interval trendlines: Symbolic singular spectrum analysis for interval time series

In this article we propose an extension of singular spectrum analysis for interval-valued time series. The proposed methods can be used to decompose and forecast the dynamics governing a set-valued stochastic process. The resulting components on which the interval time series is decomposed can be understood as interval trendlines, cycles, or noise. Forecasting can be conducted through a linear recurrent method, and we devised generalizations of the decomposition method for the multivariate setting. The performance of the proposed methods is showcased in a simulation study. We apply the proposed methods so to track the dynamics governing the Argentina Stock Market (MERVAL) in real time, in a case study over a period of turbulence that led to discussions of the government of Argentina with the International Monetary Fund.     

基于制造定制的产品工时定额快速计算方法

为了保证制造定制生产方式下能够有效、快速、精确的确定产品的工时定额,提出了一种快速制定工时定额的方法.该方法通过成组技术和模块化思想对定制产品进行模块划分;并综合考虑了实际操作和知识经验对制定时间定额的因影响作用,在时间模块的基础上建立作业模块和补偿模块;采用不同的技术手段制定其时间定额,再构建时间模块数学模型;通过时间模块的快速组合计算产品的工时定额.最后,通过实例证明了其可行性及有效性.该方法可以拓展到设计定制、装配定制等多种定制形式下的工时定额的高效制定,具有较强的通用性.     

WMN路由协议的改进与应用研究

提出了一种适用于无线Mesh网络的AODV协议的改进方案,即在相对静止的节点内构造一个基于DSDV路由的驱动表。NS-2仿真表明,改进后的AODV—D协议更适应于拓扑变化快的环境。在复杂度没有明显增加的前提下,AODV—D协议降低了平均端到端时延和丢包率,大大提高了网络性能。