多变量混沌时间序列局部多项式预测方法及应用

为了改善混沌时间序列的预测精度,提出了一种新的多变量混沌时间序列的局部多项式预测方法.它首先利用多变量时间序列的相空间重构理论重构相空间,并据此利用多项式函数构造预测模型,该模型根据嵌入维数构造数据矩阵,进行模型的参数估计和计算一步预测值,最后根据平均根统计量推断预测效果.Lorenz系统的模拟仿真和上海综合股价指数的局部预测结果表明:用多变量混沌时间序列局部多项式预测法进行预测的误差小,且比单变量混沌时间序列局部多项式预测法的预测精度高.     

国家考试演变的被会化趋势与体现国家意志

从分析国家考试管理一些变化轨迹立论,指出其社会化发展趋势,探究其产生的根源,并阐述考试的演变过程中如何体现国家意志的问题。     

认知诊断十年:基于CiteSpace的知识图谱分析

借助CiteSpace可视化软件,对Web of Science数据库中认知诊断研究近十年的成果进行知识图谱分析。结果发现:(1)认知诊断研究覆盖国家较少,美国为核心国家,中国不断逼近核心地位;(2)跨国际机构合作较为薄弱,有待加强;(3)认知诊断知识基础包括认知诊断模型、Q矩阵校准和模型-数据拟合等方面,CDCAT研究在2013年后迅速增加;(4)研究理论较多,应用研究缺乏,应不断提升认知诊断在教学、考试中的价值,助力智慧教育的实现。     

Knock prediction for dual fuel engines by using a simplified combustion model

INTRODUCTIONDuetodwindlingfueloilreservesandthedesireforreducedpollutantemissions,naturalgas,whichisdominantlycomposedofmethane,hasbeennowwidelyusedasanalternativefuelininternalcombustionengines .Aconventionaldieselenginecanbeconvertedwithoutexcessiveincr…     

High cycle fatigue life prediction and reliability analysis of aeroengine blades

Based on the nonlinear continuum damage model(CDM) developed by Chaboche,a modified model for high cycle fatigue of TC4 alloy was proposed.Unsymmetrical cycle fatigue tests were conducted on rod specimens at room temperature.Then the material parameters needed in the CDM were obtained by the fatigue tests,and the stress distribution of the specimen was calculated by FE method.Compared with the linear damage model(LDM),the damage results and the life prediction of the CDM show a better agreement with the test and they are more precise than the LDM.By applying the CDM developed in this study to the life prediction of aeroengine blades,it is concluded that the root is the most dangerous region of the whole blade and the shortest life is 58 211 cycles.Finally,the Cox proportional hazard model of survival analysis was applied to the analysis of the fatigue reliability.The Cox model takes the covariates into consideration,which include diameter,weight,mean stress and tensile strength.The result shows that the mean stress is the only factor that accelerates the fracture process.     

黄冈红色旅游文化软开发分析

红色旅游文化的开发包括硬开发和软开发,软开发是红色旅游文化深度开发的必然趋势,也是红色旅游持续发展的必由之路。国家红色旅游进入了新的发展阶段,黄冈要继续抢抓机遇,站在文化的高度来思考红色旅游文化建设,研究和谋划黄冈红色旅游文化深度软开发问题。     

透过第30届奥运会田径奖牌演变看中国竞技田径的走势

本文运用文献资料、数理统计、归纳总结等方法,通过对第30届奥运会田径比赛奖牌分布的归纳分析及与第28、29届奥运会田径比赛奖牌分布情况的比较,以及我国田径项目所取得的成绩分析,总结我国竞技田径的发展态势。     

Making DDL Engaging Through Advance Organizers and Prediction Activities

This paper addresses some of the requirements of the advance organizers and prediction activities for DDL(Data-Driv en Learning) based on multi-modal corpora for learning English as a second language.It analyzes preliminary advantages and dis advantages of using multi-modal corpora for DDL and focuses on key methodological issues related to self-guided learning and corpus operation.Pedagogical suggestions are provided on how to make the multi-modal corpora based DDL engaging in accor dance with Krashen’ s Language Input Hypothesis with the assistance of advance organizers and prediction activities.     

基于灰色分析的公安情报分析研究

随着公安信息化进程的加快,产生大量情报数据,基于其中吸毒人数数据建立灰色Verhulst模型,将灰色分析引入公安情报分析中,可以为公安情报分析提供数量依据,使得公安情报分析方法更加符合实际需要,从而得出的结论更加准确和可靠。     

高校科技英语类文章的阅读技巧

科技英语类文章在英语阅读材料中居于偏难的程度,其句式严谨,语言具有逻辑性,同时词汇专业性强,不过,再长再难的句子,仔细推敲,还是有一定的阅读技巧,该文按照信息获取,分类,整合的步骤,介绍了一种行之相对有效的方法,可以缓解读者对于此类文章的困扰。