不确定时间序列的相似性匹配研究

确定时间序列的相似性匹配方法都没有考虑数据的不确定性,而现实世界中诸如温度传感器等设备采集到的数据往往是不确定的,并且两条不确定时间序列之间的距离也是不确定的,所以现有的确定时间序列的相似性匹配方法不适用于这些领域。针对此问题,提出了基于统计学的规约算法,并且基于该算法提出了不确定时间序列相似性匹配的两种新型算法。在规约过程中,规约算法优化了不同背景下不确定时间序列的小概率点和奇异点的处理。在匹配过程中,首先提出了圆环匹配算法,它通过构建匹配圆环完成相似性匹配,并且通过多次重启提高相似性匹配的准确度和效率;然后在规约算法的基础上,提出了期望匹配的改进算法,它通过增加包络约束消除期望匹配算法中出现的误判问题。     

不确定时间序列的相似性匹配问题

确定性时间序列的相似性匹配方法都没有考虑数据的不确定性,而现实世界中传感器采集到的数据往往是不确定的,现有的时间序列的相似性匹配方法不适用于这些领域.针对此问题,将不确定性时间序列做预处理,把它分为横向时间维和纵向概率维,首先把给定的不确定时间序列用Haar小波变换进行压缩变换,在此基础上,对得到的不确定性时间序列概率维作纵向处理,提出一种选代表方法,即采用概率最大法、均值法等选出一条确定的时间序列.通过这2种预处理后,对得到的确定性时间序列进行降维和索引,根据查询序列和数据库中的时间序列中的各自的不确定性进行组合,分别提出对应组合的相似性匹配算法.     

不确定时间序列的降维及相似性匹配

不确定时间序列的每个时间点上对应一个可能取值的集合,无法给出其确定值,这种不确定性给时间序列降维处理和相似性匹配带来巨大挑战,现有的时间序列降维方法和相似性匹配算法已经无法适用。针对此问题,提出了描述统计模型,将不确定时间序列归约为3条确定时间序列,通过离散傅里叶变换（discrete Fou-rier transform,DFT）、离散余弦变换（discrete cosine transform,DCT）、离散小波变换（discrete wavelet trans-form,DWT）对模型下不确定时间序列降维;根据模型特点,提出了以观察值区间和区间集中趋势为核心的相似性匹配算法。经过实验验证,描述统计模型下DCT和DWT有良好的降维效果,提出的相似匹配算法与现有算法相比提高了匹配准确率。     

基于序列匹配和极值理论对地震趋势的研究

通过分析造成地震发生的各种因素之间的关系,提出了将极值理论和地震时间序列匹配相结合用于地震趋势研究的基本思想。针对传统地震时间序列匹配算法的不足,提出了将基于形态的时间-震级二维相似性匹配算法和极值理论相结合对未来地震趋势进行分析的方法。该方法采用时间-震级二维相似性匹配的方法寻找最佳地震匹配区域,用极值理论对该区域地震活动的复发周期和发震概率及其概率阈值进行数据处理,从而获得对该地区未来一段时间的地震趋势做出判断。以安徽及周边地区为例,阐述了应用该方法进行研究的一般步骤。     

基于多维分段和动态权重DTW的多元时间序列相似性度量方法

针对常用方法无法准确度量多元时间序列相似程度的问题,提出一种基于多维分段和动态权重动态时间弯曲距离的多元时间序列相似性度量方法.首先对多元时间序列进行多维分段拟合,选取拟合段的斜率、均值和时间跨度作为每一段的特征,在对多元时间序列降维的同时也保留了变量之间的相关性;然后提出一种动态权重动态时间弯曲距离度量方法计算多元时间序列特征矩阵之间的距离,避免了直接使用动态时间弯曲距离造成的畸形匹配问题.最终实验结果也验证了该方法在多种类型的数据集上都能取得较高的度量精度,表明了该方法的有效性.     

基于趋势的时间序列相似性度量和聚类研究

由于时间序列的长度很大,并且不确定时间序列在每个采样点的取值具有不确定性,导致时间序列在相似性匹配和聚类挖掘中时间复杂度很高,为了解决该问题,提出了基于趋势的时间序列相似性度量方法和聚类方法.其中基于趋势的相似性度量方法根据时间序列的整体变化趋势,将时间序列映射为短的趋势符号序列,并利用各趋势的一阶连接性指数和塔尼莫特系数完成相似性度量;基于趋势的聚类方法通过定义趋势高度,并对趋势符号序列迭代进行区间划分和趋势判断,并以此构建趋势树,最后将趋势树根节点中趋势符号相同的序列聚集为一类.实验结果表明:a)五种趋势符号的一阶连接性指数可唯一地表示一条时间序列;b)基于趋势的相似性度量方法在多项式时间内可有效完成时间序列的相似性匹配;c)基于趋势的聚类方法将序列的相似性度量和聚类过程集中在一起,聚类效果显著.     

时间序列相似性分析中滑动窗口宽度的确定

时间序列相似性查找作为一种非平凡问题,大多数有效的求解方法都涉及到对原数据维度的简约。在有效地保持原序列中信息量的前提下,尽可能降低计算复杂度是算法的关键所在。通过讨论滑动窗口在时间序列相似性降维算法中的实际应用情况,从中发现一种自适应确定滑动窗口宽度的新方法。通过对时序特征值分布函数挖掘,发现时间序列中的有效特征点,进而确定一组合适的滑动窗口宽度;最后根据序列的变化情况来决定最优的滑动窗口宽度,对原数据维度进行简约。     

在时间序列相似性问题中滑动窗口的确定

作为一个非平凡命题,大多数时间序列相似性查找方法都涉及到了对原数据的维度简约.在保持原序列中有效信息量的同时,尽量降低计算复杂度是这些算法的关键.讨论滑动窗口在时间序列相似性降维技术中的实际应用,从中发现确定自适应滑动窗口大小的一种新方法.通过对时序特征值分布函数的挖掘,发现时间序列中的若干有效点,从而确定一组合适的滑动窗口大小,并根据序列变化的来决定最佳的滑动窗口.     

基于极值点特征的时间序列相似性查询方法*

为了提高时间序列子序列匹配的准确度和效率,提出了基于极值点特征的时间序列相似性查询方法。首先识别出时间序列中的极值特征点,根据极值点使用多层次极值划分法对长序列进行划分;然后对划分得到的多层次子序列集使用改进的动态时间弯曲方法与查询序列进行相似性匹配;最后找到与查询序列最相似的子序列。实验表明,此方法在保证准确度的情况下大大提高了相似性搜索过程的效率。     

改进的符号化时间序列处理方法

符号化聚集近似是一种有效的时间序列数据离散化降维方法,为了扩展非等维符号化时间序列相似性度量的解决方案,提出了一种新方法。首先将关键点提取技术应用在符号化算法中对时间序列进行降维处理,然后利用文中提出的方法对非等长的时间序列进行局部等维处理,再符号化;最后采用不同的方法进行相似度对比计算。实验结果表明,这种方法是简单而有效的,并且使非等长符号化时间序列的相似性度量及聚类方法得到了拓展。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~