关系数据库中近似查询的自动采样改进方法研究

海量数据的传统精确查询易导致负载过大,而通过改进数据库近似查询自动采样,预先运行样本查询,然后根据每一个元组在样本关系表中出现的次数,将每个元组需要的存储信息作为元组的属性添加进数据表中,并通过DBMS在整个自动抽样过程对它们进行管理,对所得的结果进行分类并统计,得出每次采样过程中某个元组出现的次数,实验表明方法是有效的。     

英语教学与自主学习能力的培养

英语教学中应该重视学生自主学习能力的培养,因为一个成功的学习者首先应该是个独立的学习者。文章分析了学生培养自主学习能力的必要性,阐述了自主学习的内涵,并且对自主学习的心理发展、动机、策略等内在条件和教育指导这一外在条件分别进行了论述。最后提出了如何通过学习者训练来培养学生的英语自主学习能力的途径和方法。     

高效太阳能热水器研究

从光学、传热和结构等几个方面指出了太阳能家用热水器的主要缺点,分析了多纬度热水自动跟踪高效太阳能热水器的工作原理,并对多纬度热水自动跟踪高效太阳能热水器进行了较深入地研究.     

PLC器件在电子技术课程设计中的应用

课程设计是针对一门课程的综合训练,对学生运用理论知识解决实际问题及培养创新能力等方面有着重要作用。PLC控制技术在生产实践中应用极其广泛,对机电类专业学生进行这方面的训练是十分必要的,我们结合电子技术课程设计教学实践,采用PLC设计出教学用的自控系统,辅助教学效果显著。     

一种新的彩色图像边缘检测算法

自动阀值选取是彩色图像边缘检测的难点和关键问题,首先从人类的视觉特性出发,分析了人类视觉系统的亮度感知门限函数,利用数学建模方法和色度学方面的研究成果,给出人类视觉系统对彩色图像边缘所能识别的最小彩色差函数。利用小波边缘检测原理,给出一种能根据不同彩色背景自动选取阀值的小波边缘检测算法. 仿真实验证明算法有较好的自适应性和良好的边缘识别性能。     

A Comparison of Stimulus-Stimulus Pairing,Standard Echoic Training,and Control Procedures on the Vocal Behavior of Children With Autism

An alternating treatments design was employed to compare the effect of stimulus-stimulus pairing, standard echoic training, and a control condition on the vocal behavior of 3 preschoolers with autism. Data were recorded during pre- and postsession observations. During the stimulus-stimulus pairing condition, the experimenter''s vocal model was paired with the delivery of a preferred item. During the standard echoic training condition, the experimenter presented a vocal model and delivered a preferred item contingent on an echoic response. During the control condition, the experimenter presented a vocal model and, after a 10-s delay, presented a preferred edible item. Results from the post-session observations during the stimulus-stimulus pairing condition showed an immediate but temporary increase in the target sound for 1 participant only. Implications and suggestions for future research are provided.     

The Role of Modeling and Automatic Reinforcement in the Construction of the Passive Voice

Language acquisition has been a contentious topic among linguists, psycholinguists, and behaviorists for decades. Although numerous theories of language acquisition have surfaced, none have sufficiently accounted for the subtleties of the language that children acquire. The present study attempts to explain the role of modeling and automatic reinforcement in the acquisition of the passive voice. Six children, ages 3 to 5, participated in this study. The results indicated that the children began using the passive voice only after the experimenter modeled passive sentences. Furthermore, the usage of the passive voice increased with repeated exposure to the experimenter''s verbal behavior. Given that the children were not explicitly reinforced, it is proposed that their behavior was automatically reinforced for using the passive voice.     

利用语法树和算符优先法构造的自动计算系统

针对编程过程中常见的公式更改及扩充情况，设计了一种基于语法树和算符优先法的计算系统，可提供公式输入、界面维护以及动态计算的完整功能．     

基于MATLAB教学平台的自动控制理论教学改革探索

文章分析了自动控制理论课程的特点和传统教学模式中存在的问题，讨论了控制系统仿真软件MATLAB在控制理论课程教学中的应用和由此带来的改革效应，并在教学过程中进行了实践探索。     

试论最小假设模型运用于外语阅读教学

M cKoon和Ratc liff(1992)提出的最小假设模型区分了自动推理和策略推理;自动推理是该模型的核心,有助于阅读理解的顺利进行。本文旨在探讨这一模型运用于外语阅读教学时可能存在的问题。