基于OLPP符号表示的时间序列分类算法

基于符号表示的时间序列分类方法是时间序列数据挖掘的关键技术.大部分现有方法主要针对单个时间序列样本进行符号表示,没有考虑样本间的近邻关系对符号化分类的影响.对此提出一种基于正交局部保持映射(Orthogonal Locality Preserving Projection,OLPP)的时间序列符号表示方法.使用OLPP...     

生成符号网络函数的新方法

本文提出一个生成符号网络函数的新方法:广义特征多项式法。该方法具有计算量小和精度高等优点,它优于现有的其它各种解决同类问题的方法。     

Approximately bisimilar symbolic models for randomly switched stochastic systems

In the past few years there has been a growing interest in the use of symbolic models for control systems. The main reason is the possibility to leverage algorithmic techniques over symbolic models to synthesize controllers that are valid for the concrete control systems. Such controllers can enforce complex logical specifications that are otherwise hard (if not impossible) to establish on the concrete models with classical control techniques. Examples of such specifications include those expressible via linear temporal logic or as automata on infinite strings. A relevant goal in this research line is in the identification of classes of systems that admit symbolic models: in particular, continuous-time systems with stochastic or hybrid dynamics have been only recently considered, due to their rather general and complex dynamics. In this work we make progress in this direction by enlarging the class of stochastic hybrid systems admitting finite, symbolic models: specifically, we show that randomly switched stochastic systems, satisfying some incremental stability assumption, admit such models.     

An on-line SAX and HMM-based anomaly detection and visualization tool for early disturbance discovery in a dynamic industrial process

In order to achieve an optimum and successful operation of an industrial process, it is important firstly to detect upsets, equipment malfunctions or other abnormal events as early as possible and secondly to identify and remove the cause of those events. Univariate and multivariate statistical process control methods have been widely applied in process industries for early fault detection and localization.The primary objective of the proposed research is the design of an anomaly detection and visualization tool that is able to present to the shift operator – and to the various levels of plant operation and company management – an early, global, accurate and consolidated presentation of the operation of major subgroups or of the whole plant, aided by a graphical form.Piecewise Aggregate Approximation (PAA) and Symbolic Aggregate Approximation (SAX) are considered as two of the most popular representations for time series data mining, including clustering, classification, pattern discovery and visualization in time series datasets. However SAX is preferred since it is able to transform a time series into a set of discrete symbols, e.g. into alphabet letters, being thus far more appropriate for a graphical representation of the corresponding information, especially for the shift operator. The methods are applied on individual time records of each process variable, as well as on entire groups of time records of process variables in combination with Hidden Markov Models. In this way, the proposed visualization tool is not only associated with a process defect, but it allows also identifying which specific abnormal situation occurred and if this has also occurred in the past. Case studies based on the benchmark Tennessee Eastman process demonstrate the effectiveness of the proposed approach. The results indicate that the proposed visualization tool captures meaningful information hidden in the observations and shows superior monitoring performance.     

A symbolic model checking approach to verifying satellite onboard software

This paper discusses the use of symbolic model checking technology to verify the design of an embedded satellite software control system called the attitude and orbit control system (AOCS). This system is mission critical because it is responsible for maintaining the attitude of the satellite and for performing fault detection, isolation, and recovery decisions. An executable AOCS implementation by Space Systems Finland has been provided in Ada source code form, and we use the input language of the symbolic model checker NuSMV 2 to model the implementation at a detailed level. We describe the modeling techniques and abstractions used to alleviate the state space explosion due to the handling of timers and the large number of system components controlled by the AOCS. The required behavior has been specified as extended state machine diagrams and translated to temporal logic properties. Besides well-known LTL and CTL model checking algorithms, we adapt a previously unexplored form of the liveness-to-safety approach to the problem. The latter new technique turns out to successfully prove all desired properties of the system, outperforming both the LTL and CTL implementations of NuSMV 2.     

Thermoelastic Analysis of Functionally Graded Rotating Disks with Variable Thickness Involving Non-Uniform Heat Source

The research aims to investigate thermoelastic behavior of functionally graded rotating disks with variable thickness involving a non-uniform heat source. We assume material properties and thickness of rotating disks to vary in the radial direction. Axisymmetric thermal loads including non-uniform heat source, heat flux, and temperature boundary conditions are considered. To conduct corresponding simulations, two user subroutines are edited and incorporated into the commercial finite-element code ABAQUS. For verification, analytical formulations are derived and solved uniquely by symbolic calculations using the computing software Mathematica. The developed finite-element technique is then verified with very good agreement between results by ABAQUS and Mathematica.     

当代城市空间的符号价值

随着中国发达地区城市由生产社会向消费社会的转型,空间呈现商品化的发展态势,空间符号价值的重要性也日益突显出来。一方面,城市空间所象征的个性和品位、身份和地位、生活方式等符号意义逐渐成为大众空间消费过程中所关注的重点;另一方面,空间符号的消费强化了空间的社会属性,并为城市带来新的发展契机。     

实用主义代码70后中国建筑师之建筑数字观

文章指出,70后中国建筑师站在计算机带来的新技术变迁的时代前沿从电脑普及化到电脑计算化,首当其冲受到技术革命带来的设计方法和过程改变的洗礼,从而对数字设计具有敏锐触觉。70后受到的教育延续布扎体系,深悉建筑本质：几何形态、空间、质感,光线和建构。＂建房子＂的迫切需求让70后的数字时代的建筑观具有强烈实用主义的特征,这样的特征给在中国建筑实践和教育中崛起的70后带来了产生新建筑形态语言和思潮可能的机会。     

营造之后的解读辽宁营口鲅鱼圈金泰文化艺术广场综合设计

文章简要分析了营口鲅鱼圈金泰文化艺术广场,一个聚合了大剧院、图书馆、文化广场、标志塔为一体的综合性项目的设计和建造过程,阐述了高质量完成政府类大型公共项目的方法,并对该项目的设计理念进行解读.