基于回归算法与多层次分布式智能决策支持系统的设计

讨论了多元线性回归模型及其在区域经济中的应用.在研究一元线性回归模型、未知参数的估计及参数的检验的基础上,详细的讨论了多元线性回归模型、未知参数的估计及其参数的检验问题.重点以某地区国民生产总值数据资料为例介绍多元线性回归算法在区域经济中的应用,可以对区域经济进行很好的计算和预测.     

基于ARMA模型的联机时间序列数据分割算法

自回归移动平均(ARMA)模型近年来被广泛用于时间序列数据的预测、聚类以及相似性查找等.由于现实中的时间序列数据其底层生成机制与结构经常动态发生变化,因而对跨越较长时期的数据建立一个单一静态的ARMA模型并不合适.本文提出一种联机分割算法,首先对数据建立动态的ARMA模型,然后根据模型的预测信息与历史数据的特征信息,判断是否适合继续使用该模型描述后续数据,或者需要对数据进行分割,从而逐段建立ARMA模型.算法能够处理持续数据流,对仿真数据与实际数据的试验结果表明,本文所提出的算法是实用有效的.     

基于时间序列分析的分布式拒绝服务攻击检测

该文分析了分布式拒绝服务(DDoS)攻击的特点,提出了一种基于流连接密度(FCD)时间序列分析的DDoS攻击检测方法,该方法通过拟合FCD时间序列的自适应自回归模型,获得能够在多维空间描述当前流量状态的AAR模型参数向量序列,然后使用经过样本训练的支持向量机(SVM)分类器进行攻击识别;充分考虑了报警的时间间隔及分布情况,提出一种报警可信度评估算法对SVM分类结果进行二次处理,以消除网络流量噪声及分类错误所带来的影响．实验结果显示,该检测方法能够有效检测DDoS攻击,可信度评估算法能够明显减少误报,降低误报率,显著提高检测质量．     

基于分段线性动态时间弯曲的时间序列聚类算法研究

时间序列是一类重要的复杂类型数据，时间序列知识发现正成为知识发现的研究热点之一。欧几里德距离及其扩展作为相似测度被广泛应用于时间序列的比较中，但是这种距离测度时数据没有好的鲁棒性。动态时间弯曲技术是基于非线性动态编程的一种模式匹配算法，但是其计算复杂性相当高。本文提出了基于时间序列分段线性表示的动态时间弯曲算法，通过计算线性分段序列数据之间的最短弯曲路径来获得序列的匹配。对综合控制时间序列数据进行基于不同距离测度的聚类分析对比结果表明本文提出的算法有很高的精度和时振幅差异、嘈声和线性漂移有强的鲁棒性，大大降低计算复杂性，具有良好的应用价值。     

小波与时间序列在数字信号质量监测中的应用

描述了小波和时间序列分析在数字信号质量监测中的应用。与传统监测信号方法不同,这种方法从被测信号的组成成分入手,通过小波变换对原始信号依尺度分解成不同层次,并从其中提取特征信号,同时对其建立自回归滑动平均(ARMA)模型,通过分析ARMA模型的参数得出信号的质量状况。另外还描述了如何根据被分析信号的特征、小波重构信号的能力及计算速度选择合理的小波基的方法。     

一种周期时间序列的预测算法

时间序列分析作为现代数据分析处理的有效方法之一,目前广泛地应用于商业、金融、证券、电信等领域,由于人们生活及消费模式的自然规律性,时间序列往往呈现出明显的周期变化趋势。论文依据移动通信网管测量数据,提出了一种针对周期时间序列的线性预测算法——自循环算法,实验表明预测精度高于传统的线性预测分析方法。     

基于FSS时间序列分析的DDoS检测算法

通过分析分布式拒绝服务(DDoS)攻击的特征和攻击发生时数据流五元组熵值的变化,提出一种基于数据流结构稳定性(FSS)的检测算法。采用AR自回归模型估计FSS时间序列多维特征参数,使用经过样本训练的支持向量机对特征参数进行分类来识别攻击。经实验验证,该算法具备较高的检测质量。     

基于n阶原子模板的时间序列相似匹配算法

本文以时间序列一、二阶原子模式的定义为基础,推导基于n阶原子模式的构造,研究了原子模式之间的偏序相似关系,使得序列能进行细腻的比较,并由此提出了基于模板匹配的算法。实验表明,基于模板匹配的算法与同类方法和传统方法比较在精度上和性能上都有较大优势。     

基于时间序列分析的Web服务器DDoS攻击检测

摘要: 分布式拒绝服务攻击(Distributed Denial of Service, DDoS)的目标是破坏网络服务的有效性,是当前Web服务安全的主要威胁之一。本文提出了一种基于时间序列分析的DDoS攻击检测方法。该方法利用网络流量的自相似性,建立Web流量时间序列变化的自回归模型,通过动态分析Web流量的突变来检测针对Web服务器的DDoS攻击。在此基础上,通过对报警数据的关联分析,获得攻击的时间和位置信息。实验结果表明：该方法能有效检测针对Web服务器的DDoS攻击。     

基于社会网络的个人需求预测算法研究

随着网上社会交互的增长,商业企业正在积累大量以前对它们来讲是无法获得的数据,比如,消费者个体的消费习惯以及人际关系网,分析这些数据不仅可以揭示消费者需求,而且可以用来设计未来的社会计算应用。讨论向量自回归条件异方差模型如何被应用于社会网络的动态信息流的分析。为了管理不确定性,引入一些随机变量,这些随机变量会不断地被预测的各个阶段所积累,但通过使用时间序列分析大大地减轻了这种状况。通过模拟现实场景,使用向量自回归条件异方差模型得到彼此影响的预测结果。仿真结果表明该方法具有较好的预测评估准确率。     

An intelligent decision support system for digital preservation

This paper describes a Service Oriented Architecture (SOA) based on Web services technology designed to assist cultural heritage institutions in the implementation of migration based preservation interventions. The proposed SOA delivers a recommendation service and a method to carry out complex format migrations. The recommendation service is supported by three evaluation components that assess the quality of every migration intervention in terms of its performance (Migration Broker), suitability of involved formats (Format Evaluator) and data loss (Object Evaluator). Throughout the paper the whole workflow between these three components is explained in detail as well as the most relevant tasks that are carried out internally in each of them. The proposed system is also able to produce preservation metadata that can be used by client institutions to document preservation interventions and retain objects’ authenticity. Although the primary goal of this SOA is the implementation of migration based preservation interventions, it can also be used for other purposes such as comparing file formats or evaluating the performance of conversion applications.     

A decision support system methodology for forecasting of time series based on soft computing

Exponential procedures are widely used as forecasting techniques for inventory control and business planning. A number of modifications to the generalized exponential smoothing (Holt-Winters) approach to forecasting univariate time series is presented, which have been adapted into a tool for decision support systems. This methodology unifies the phases of estimation and model selection into just one optimization framework which permits the identification of robust solutions. This procedure may provide forecasts from different versions of exponential smoothing by fitting the updated formulas of Holt-Winters and selects the best method using a fuzzy multicriteria approach. The elements of the set of local minima of the non-linear programming problems allow us to build the membership functions of the conflicting objectives. It is compared to other forecasting methods on the 111 series from the M-competition.     

An intelligent decision support system for management of petroleum-contaminated sites

Groundwater and soil contamination resulted from LNAPLs (light nonaqueous phase liquids) spills and leakage in petroleum industry is currently one of the major environmental concerns in North America. Numerous site remediation technologies have been developed and implemented in the last two decades. They are classified as ex-situ and in-situ remediation techniques. One of the problems associated with ex-situ remediation is the cost of operation. In recent years, in-situ techniques have acquired popularity. However, the selection of the optimal techniques is difficult and insufficient expertise in the process may result in large inflation of expenses. This study presents an expert system (ES) for the management of petroleum contaminated sites in which a variety of artificial intelligence (AI) techniques were used to construct a support tool for site remediation decision-making. This paper presents the knowledge engineering processes of knowledge acquisition, conceptual design, and system implementation. The results from some case studies indicate that the expert system can generate cost-effective remediation alternatives to assist decision-makers.     

面向虚拟采办的智能决策支持系统概念框架

提出一种面向虚拟采办全寿命周期、全系统、全方位决策的智能决策支持系统SBA—IDSS概念框架．作为真实世界采办最终需求的抽象描述,它属于与实现无关的规范性模型体系,由它定义应用领域、用户概念和环境特征．同时它是数字世界中拟实现的初始工程模型,包括与实现无关的设计可行性模型、规划模型及功能顶层分解．该框架支持系统的自组织、自适应智能行为,预期可按需组成模型与仿真、文件、知识、通信及数据驱动的各类实用决策支持系统．该框架通过一项SBA实例的验证,得到可用性的正面评价．     

Evolutionary algorithm enhancement for model predictive control and real-time decision support

Effective decision support and model predictive control of real-time environmental systems require that evolutionary algorithms operate more efficiently. A suite of model predictive control (MPC) genetic algorithms are developed and tested offline to explore their value for reducing combined sewer overflow (CSO) volumes during real-time use in a deep-tunnel sewer system. MPC approaches include the micro-GA, the probability-based compact GA, and domain-specific GA methods that reduce the number of decision variable values analyzed within the sewer hydraulic model, thus reducing algorithm search space. Minimum fitness and constraint values achieved by all GA approaches, as well as computational times required to reach the minimum values, are compared to large population sizes with long convergence times. Optimization results for a subset of the Chicago combined sewer system indicate that genetic algorithm variations with a coarse decision variable representation, eventually transitioning to the entire range of decision variable values, are best suited to address the CSO control problem. Although diversity-enhancing micro-GAs evaluate a larger search space and exhibit shorter convergence times, these representations do not reach minimum fitness and constraint values. The domain-specific GAs prove to be the most efficient for this case study. Further MPC algorithm developments are suggested to continue advancing computational performance of this important class of problems with dynamic strategies that evolve as the external constraint conditions change.     

An evolutionary algorithm-based decision support system for managing flexible manufacturing

The high investment cost of flexible manufacturing systems (FMS) requires their management to be effective and efficient. The effectiveness in managing FMSs includes addressing machine loading, scheduling parts and dispatching vehicles and the quality of the solution. Therefore the problem is inevitably multi-criteria, and decision maker's judgement may contribute to the quality of the solution and the systems's performance. On the other hand, each of these problems of FMS is hard to optimize due to the large and discrete solution spaces (NP-hard). The FMS manager must address each of these problems hierarchically (separately) or simultaneously (aggregately) in a limited time. The efficiency of the management is related to the response time.

Here we propose a decision support system that utilizes an evolutionary algorithm (EA) with a memory of “good” past experiments as the solution engine. Therefore, even in the absence of an expert decision maker the performance of the solution engine and/or the quality of the solutions are maintained.

The experiences of the decision maker(s) are collected in a database (i.e., memory-base) that contains problem characteristics, the modeling parameters of the evolutionary program, and the quality of the solution. The solution engine in the decision support system utilizes the information contained in the memory-base in solving the current problem. The initial population is created based on a memory-based seeding algorithm that incorporates information extracted from the quality solutions available in the database. Therefore, the performance of the engine is designed to improve following each use gradually. The comparisons obtained over a set of randomly generated test problems indicate that EAs with the proposed memory-based seeding perform well. Consequently, the proposed DSS improves not only the effectiveness (better solution) but also the efficiency (shorter response time) of the decision maker(s).     

A model updating strategy for predicting time series with seasonal patterns

Traditional methodologies for time series prediction take the series to be predicted and split it into training, validation, and test sets. The first one serves to construct forecasting models, the second set for model selection, and the third one is used to evaluate the final model. Different time series approaches such as ARIMA and exponential smoothing, as well as regression techniques such as neural networks and support vector regression, have been successfully used to develop forecasting models. A problem that has not yet received proper attention, however, is how to update such forecasting models when new data arrives, i.e. when a new event of the considered time series occurs.This paper presents a strategy to update support vector regression based forecasting models for time series with seasonal patterns. The basic idea of this updating strategy is to add the most recent data to the training set every time a predefined number of observations takes place. This way, information in new data is taken into account in model construction. The proposed strategy outperforms the respective static version in almost all time series studied in this work, considering three different error measures.     

面向不等长多维时间序列的聚类改进算法

针对已有基于模型的多维时间序列（MTS）聚类算法处理不等长MTS速度较慢的问题,提出了一种基于LR分量提取的MTS聚类算法（MUTSCA〈LRCE〉）。首先,采用等频离散化方法符号化MTS;然后,计算用于表达MTS样本各维时间序列之间时序模式的LR向量,对每个LR向量进行排序后从其两端提取固定数目的不同关键分量,所有提取的关键分量拼接形成表示MTS样本的模型向量,该过程将不等长MTS样本集转换为等长的模型向量集;最后,采用k-means算法对生成的等长模型向量集进行聚类分析。在多个公共数据集上的实验结果表明,与基于模型的MTS聚类算法——MUTSCA〈LR〉相比,所提算法能够在保证聚类效果的前提下,显著提高不等长MTS数据集的聚类速度。     

Linear time algorithm for finding a picture''s connected components

An algorithm that identifies the connnected components of a thresholded digitized picture is presented. The time complexity of the algorithm is linear in the number of runs of object pixels in the picture.     

Agent-based intelligent system development for decision support in chemical process industry

This paper presents an agent-based intelligent system to support coordinate manufacturing execution and decision-making in chemical process industry. A multi-agent system (MAS) framework is developed to provide a flexible infrastructure for the integration of chemical process information and process models. The system comprise of a process knowledge base and a group of functional agents. Agents in the system can communicate and cooperate with each other to exchange and share information, and to achieve timely decisions in dealing with various scenarios in process operations and manufacturing management. Process simulation, artificial intelligent technique, rule-based decision supports are integrated in this system for process analysis, process monitoring, process performance prediction and operation suggestion. The implementation of this agent-based system was illustrated with two case studies, including one application in process monitoring and process performance prediction for a chemical process and one application in de-bottlenecking of a site utility system.