改进DTW下界函数的距离度量方法研究

动态时间弯曲算法（DTW）是一种常见的时间序列相似性度量方法,对数据挖掘任务起着至关重要的作用。针对现有DTW算法的时间复杂度高、度量精确度一般的特征,提出一种DTW下界函数的提前终止算法（LB_ESDTW）。引入提前终止思想,提高算法的执行效率;再在提前终止算法思想的基础上,与DTW下界函数相结合,提出一种基于提前终止DTW的下界函数算法（LB_ESDTW）。该算法在保证高效的运行时间效率的同时,也使得算法的度量准确率得到了提升。实验结果表明,LB_ESDTW在绝大部分时间序列数据集中,都表现出良好的适应性,针对不同类别的时间序列,都能有良好的度量性能。     

基于局部梯度和二进制模式的时间序列分类算法

时间序列分类问题是时间序列数据挖掘中的一项重要任务, 近些年受到了越来越广泛的关注. 该问题的一个重要组成部分就是时间序列间的相似性度量. 在众多相似性度量算法中, 动态时间规整是一种非常有效的算法,目前已经被广泛应用到视频、音频、手写体识别以及生物信息处理等众多领域. 动态时间规整本质上是一种在边界及时间一致性约束下...     

一种基于包排队方式的网络路径可用带宽探测方法

对IP网络路径带宽的探测是目前网络研究领域的一个热点。本文提出了一种针对端到端的网络、基于包排队方式的双向双步长网络路径可用带宽的探测方法。该探测方法由时延监视和UDP发送两个进程组成，基于包的排队时延来获取路径的可用带宽，并通过采用双向双步长的方法来递增或递减UDP包的发送速率。所提出的探测方法可以明显减少探测次数和运行时间，从而降低探测带来的开销。实验结果显示，所设计的方法和技术是可行的和有效的。     

随机系统中能容忍连续丢包和测量时延的卡尔曼滤波

通过转换原线性系统到能容忍连续丢包和测量时延的随机参数系统,推导了一个最优线性滤波器.给出一个仿真例子,比较已存在的结果,仿真结果表明被提出的线性滤波器有优越的性能.然而,该滤波器不能应用于非线性系统.从应用角度,为非线性系统提出了一个增强型的滤波器.而且,该增强型的滤波器能成功地应用于不可靠的无线传感器网络场景来跟踪移动目标.这些滤波器只依靠测量值的达到概率,而不需要知道某一时刻测量是否接收.仿真说明了被提出的增强型滤波器不仅能改善实时目标跟踪的鲁棒性,而且比标准的扩展卡尔曼滤波器能够提供更精确的估计.     

Measurement designs to improve the computational efficiency of linear system state estimators

A design procedure for the measurement process is proposed to decrease the computational burden of state estimation in linear discrete-time systems. System order reduction is involved, which is achieved by a derived transformation, yielding an alternative system and measurement process representation that includes time delays in both the system and the measurement process. Without loss of filter optimality, measurement designs yielding reductions in the computational requirements of the Kalman filter applied to the reduced order system are derived. A computational comparison is included to show that the proposed method, as opposed to the direct application of the Kalman filter, can yield large reductions in the filter computation time.     

水泥熟料质量软测量模型中的时序分析方法

针对常规水泥熟料质量软测量模型未充分考虑过程变量间时序信息的问题,本文根据水泥生产流程工艺的时滞性、连续性特点,提出了一种时序分析方法,以提高熟料中游离氧化钙含量的软测量准确度.首先根据物料的传输机理,估算出物料在各工艺设备中的停留时间,在此基础上将软测量模型的输入输出变量进行时序匹配,之后采用类高斯函数对各输入变量匹配时刻前后的时序数据进行加权,获得具有时序信息的输入–输出样本对,然后以支持向量机模型结构为例,对引入时序信息后的游离氧化钙含量软测量模型进行训练和测试,并讨论了时序参数对结果的影响.采用某水泥生产线的实际过程数据对本文模型与方法进行验证,结果表明,该模型预测值与实际的游离氧化钙含量吻合良好,能正确预测其变化趋势;将本文模型测量结果与未使用时序信息的常规支持向量机模型对比,结果表明,过程变量间的时序信息有助于提高水泥熟料质量软测量模型的精度.本文提出的时序分析方法为水泥生产等流程工业过程建立软测量模型提供了新思路.     

Differentiator-based time delay control for uncertain robot manipulators

High-quality acceleration signal plays a significant role in fast and precise trajectory tracking of robot manipulators via time delay control (TDC). This paper proposes a fast transient tracking differentiator (FTD) for obtaining the noise-less time derivative from a noisy measurement within the framework of tracking differentiator (TD) design methodology. Global asymptotic convergence of the proposed FTD is proven by Lyapunov's direct method and TD theory. The proposed FTD is cascaded to construct an acceleration estimation and is integrated with the commonly used TDC for an improved trajectory tracking of robot manipulators in the presences of parametric uncertainties and bounded disturbances. Numerical simulations and real-time experimental validation comparisons demonstrate that the proposed approach provides an easy-going model-free improved design for fast and accurate trajectory tracking of robot manipulators with position measurement only.     

Adaptive tracking system for a manoeuvring target using images with correlated noises

An effective scheme is proposed for estimating the state parameters of a manoeuvring target from a noisy image sequence, providing the sequence contains correlated noises and the trajectory of the target is disturbed by an unknown acceleration. For the correlated noises, a first-order difference operator is applied to the original image sequence to generate an artificial measurement sequence with only uncorrelated white noises. For the unknown acceleration, a Kalman filter augmented by a semi-Markov process and the bayesian theory is applied to form an adaptive filter. In the proposed tracking system, the filter first generates an artificial measurement at each sampling time from the observation. It then utilizes an artificial measurement sequence up to the current time instance to predict the a posteriori probability of each possible acceleration state. The weighted average of acceleration, where the weight is the a posteriori probability, is applied to derive the optimal estimates of the state parameters. Several computer simulations with external force applied at unknown times are performed to demonstrate the applicability and superiority of the proposed system.     

Precise evaluation of LCD gray‐to‐gray response time based on a reference pattern synchronous measurement using high speed charge‐coupled device camera

A reference pattern method based on synchronous measurement for evaluating the response time of liquid crystal display was proposed to overcome the shortcomings of the unsmooth response curve induced by the backlight modulation. The feasibility of the method is verified by measurement using a high speed charge‐coupled device camera. The measured gray‐to‐gray response time results are compared with those obtained from standard measurement approach. The results indicate that the proposed method improves the accuracy and repeatability of the response time measurement.     

一种提高溶解氧测定响应速度的方法

研究了溶解氧测定仪的响应时间影响因素,提出了一种提高溶解氧测定的响应速度的方法;利用在电流电压转换电路的精密电阻上并联一个储能电容,该电容在测量系统断电之后,能够继续给溶解氧测定的阴极和阳极提供0.2 V左右的极化电压;在溶解氧进行多次测量的时候,测量系统通电之前被测溶液已经有了一个低电压预极化的过程,可以大幅降低0.68 V极化电压对被测溶液的极化时间。测试结果显示,该方法与没有使用储能电容预极化系统相比,响应时间能减少40%。