DEA两个基本模型研究概述

主要探讨了DEA中的两个基本模型．首先,简要回顾了有关DEA模型的研究进展;接着,介绍了DEA研究中常用的两个基本模型：CCR模型及BCC模型,以及基于CCR模型的其他相关模型;最后,对CCR模型和BCC模型做了比较分析,并指出CCR模型和BCC模型各自的生产可行性／可能性集合是不同的．因此,CCR模型的边界具有线性特征,而BCC模型的边界具有分段线性特征,并呈现凹特性．     

化学教学中引领学生模型认知的思考与探索

《高中化学课程标准(征求意见稿)》中学科核心素养部分的"模型认知"是指"基于模型的认知",其中的模型包括实物模型和非实物的形式模型两大类,形式模型又包括数学模型、图像模型和语义模型等情况;模型的建构有根据原型进行建模、针对问题解决建模和从理论出发建模等路径.化学教学要引领学生模型认知,应该帮助学生树立模型意识,体会模型价值,并指导他们用适合自己的方式进行模型表达,以促进学生逐渐将模型认知固化为自己学习的一种重要方式.     

基于结构方程模型改进ARMA模型参数估计

自回归移动平均模型（ARMA模型）是目前最常用的拟合平稳序列的模型,分为AR模型、MA模型和ARMA模型三大类。通常将自回归模型（AR）、移动平均模型（MA）或自回归移动平均模型（ARMA）,称作ARIMA模型体系,是一个重要的预测工具,成为时间序列分析中许多基本思想的基础。针对时间序列数据分析中ARMA模型的识别、建立和估计问题,提出一种将SEM结构方程应用于ARMA模型参数估计的改进算法,以加快计算的收敛速度和提高模型参数估计的精确度。通过将时间序列数据的协方差式子进行变换,发现其结果满足结构方程对变量协方差的要求。结果表明,可以将SEM结构方程应用于ARMA模型来处理时间序列模型数据。     

“模型认知”是重要思维方式

“模型认知”是重要的化学学科思维方式,要从化学模型、化学认识模型等视角理解“模型认知”的内涵.从化学模型视角看,“模型认知”包含运用化学模型化学表征的能力、运用化学模型解释和论证的能力、运用化学模型预测和验证的能力、构建和优化化学模型的能力等;从化学认识模型视角看,“模型认识”包含运用化学认识模型将知识功能化,基于化学认识模型发展学生的自我评价、自我调控能力等.     

科学教育中模型定义及其分类研究述评

模型和建模研究目前已成为国际科学教育的重要研究议题之一,越来越多国家的科学教育标准强调模型和建模的作用,并将其纳入学业要求中。深入理解模型是科学教育研究者和教师有效开展模型和建模研究及进行模型相关教学的重要基础。模型定义和模型分类是认识模型的两个重要方面。模型定义的核心内容为模型是事物的表征,事物的内涵广泛,包括实物、事件、过程、概念、观点和系统等。基于模型功能的视角可以将模型分为八类:尺度模型、类比模型、图像和符号模型、数学模型、不表示数学关系的图表和表格、理论模型、概念-过程模型、系统模型。每类模型的功能和适用范围各不相同,但都可以用于理科教学之中。     

理解“模型认知”素养的不同视角

"模型认知"是化学学科核心素养的重要方面,应从化学模型、认识模型两个视角理解其内涵。从化学模型视角看,"模型认知"包含运用化学模型表征的能力、运用化学模型解释和论证的能力、运用化学模型预测和验证的能力、构建和优化化学模型的能力等;从认识模型视角看,"模型认知"包含运用认识模型将知识认识化、思路化、功能化,运用认识模型助推能力的发展,学习过程中运用认识模型进行自我评价、自我调控等。     

注塑成型充填阶段模拟中的黏度模型比较

阐述了常用的热塑性塑料幂律模型、二阶模流模型、Cross模型和Carreau模型等黏性模型表达式和特点。利用仿真的方法得出不同模型下熔体的填充速度、剪切率、剪切应力与温度这4个参数随时间变化曲线,再利用试验的方法采样得到实测值。把仿真值和实验值相对比,得到不同黏性模型的适用场合。结果表明,幂律模型和Carreau模型描述熔体填充速度时比较准确,在填充初始时描述剪切应力和温度变化率时可应用二阶模流模型、Cross模型或Carreau模型,填充后期采用幂律模型更加准确。该结果为合理选取热塑性塑料注射成型CAE填充模拟时材料的黏性模型提供了依据。     

模型认知解读及教学思考——以化学学科为例

模型是人们为了某种特定目的而对认识对象所作的一种简化的描述。按照代表和反映原型的方式,模型可以分为物质模型和思想模型。模型的认知功能主要包括描述、解释、预见、判断。在模型认知的教学中,可以将模型展示与模型建构相结合,提升学生的思维能力;将模型观察与模型制作相结合,提升学生的实践能力;将模型建构与模型演变相结合,培养学生的科学精神;将模型建构与问题解决相结合,培养学生的解题能力。     

三维线框模型生成全参数化模型方法研究

针对船体母型船模型由原先的线框模型转化为CATIA全参数化模型的相关问题,以SPD设计软件输出线框模型数据为基础,运用CATIA CAA二次开发技术手段,对转化生成全参数化模型方法进行了研究。开发软件工具高效处理面片模型,读取零件属性数据,以面片模型为基础,匹配属性数据作为输入参数,自动构建板架模型。实现了原有线框模型到CATIA平台全参数化模型的转化。     

谈应用物理模型解题

高中物理模型,按不同的标准可以分为无数种,但从运动轨迹上分,不外乎直线运动模型和曲线运动模型.由于直线运动模型较为普遍,本文就以贯穿高中物理始终的曲线运动的两种原始模型,即平抛运动模型和圆周运动模型为基本模型来谈谈应用物理模型解题.     

Standard Deviation for Small Samples

Neater representations for variance are given for small sample sizes, especially for 3 and 4. With these representations, variance can be calculated without a calculator if sample sizes are small and observations are integers, and an upper bound for the standard deviation is immediate. Accessible proofs of lower and upper bounds are presented for a broad spectrum of readers.     

Dumbing down educational research: a response to John Wilson

The scheme offers operational guides based upon identifiable behaviours in a number of technical subjects classified, for rating purposes, with cognitive, affective and motor‐manipulative taxonomies. Two dimensions are postulated for each taxonomy, (i) complexity and (ii) extensiveness. The stages are briefly illustrated by reference to skilled performance in a number of crafts. Instructions for using the rating schedule to derive three profiles relevant to attainment are provided. Interpretations of profiles are suggested, including a tentative method for aggregating numerical scores for comparison with established examination grades at ‘O’ level and CSE. The results from a trial run with a simple version of the scheme are reported and discussed.

     

On the Estimation of Nonlinear Mixed-Effects Models and Latent Curve Models for Longitudinal Data

Nonlinear models are effective tools for the analysis of longitudinal data. These models provide a flexible means for describing data that follow complex forms of change. Exponential and logistic functions that include a parameter to represent an asymptote, for instance, are useful for describing responses that tend to level off with time. There are forms of nonlinear latent curve models and nonlinear mixed-effects model that are equivalent, and so given the same set of data, growth function, distributional assumptions, and method of estimation, the 2 models yield equivalent results. There are also forms that are strikingly different and can yield different interpretations for a given set of data. This article discusses cases in which nonlinear mixed-effects models and nonlinear latent curve models are equivalent and those in which they are different and clarifies the estimation needs of the different models. Examples based on empirical data help to illustrate these points.     

和谐社会与当代大学生诚信建设

诚信是为人之本，是中华民族的传统美德，是构建和谐社会的重要基石。诚信建设对于构建和谐社会具有重大的意义。培养诚信品质是构建和谐社会对当代大学生提出的时代要求。针对当代大学生诚信缺失现象，在构建和谐社会背景下，开展大学生诚信建设应将加强诚信教育、构建良好的诚信氛围、建立健全诚信体制结合起来。     

Service‐Learning in Supply Chain Management: Benefits,Challenges and Best Practices

Service‐learning (SL) is a pedagogical approach in which students are assigned a course‐related project in a not‐for‐profit organization, and are tasked to apply course content to execute the project. While the benefits are multifarious, only recently have supply chain management (SCM) courses adapted this innovative teaching methodology. The present article aims to popularize this pedagogical concept by providing a detailed overview of the background, development, implementation, and success of an SL project in an undergraduate SCM course; this serves as a “how to” guide for instructors interested in implementing the approach. Compelling evidence for the value of SL is provided by data assessing the students’ learning experiences, and benefits for participating organizations are demonstrated. Caveats and challenges are noted, and ensuing best practices for SL are presented.     

对“研究型教师”研究的反思

“研究型教师”是目前我国教育界讨论的热点问题之一,其研究内容主要涉及到什么是研究型教师、研究型教师的素质结构和怎样培养研究型教师等。研究存在的问题是,对研究型教师的要求过于理想化;研究型教师的角色定位不准;研究型教师的研究内容不明;培养策略过于泛化,未能体现出教师专业成长规律等。     

为“汉字”重新定义

"文字是有声语言的书面表达形式"、"文字是有声语言的辅助交际工具",等等,是我们常见的汉字定义,似乎也成了一种共识。申小龙教授提出"汉字是汉民族思维和交际最重要的书面符号系统",突显人文性是该定义的最大贡献,也是对前人"单线进化论"误区和盲端的指正,但它似乎也糅入了模糊概念。笔者立于伟人们的肩上,对汉字定义作了修正。希望在纲举目张之词的定义背后给人们带来更多的思考和启示;另一面,也希望辞书界为该词下一个合理定义,以更好地指导语用。     

Use of probabilistic and deterministic measures to identify unfavorable earthquake records

This study introduces measures to identify resonant （concentration of energy in a single or a few frequencies） or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometric properties of the power spectral density function （PSDF） of the ground acceleration are developed first. Subsequently, deterministic measures for the frequency content of the ground acceleration are also developed. These measures are then used for identifying resonance and criticality in stochastic earthquake models and 110 acceleration records measured at rock, stiff, medium and soft soil sites. The unfavorable earthquake record for a given structure is defined as the record having a narrow frequency content and dominant frequency close to the structure fundamental natural frequency. Accordingly, the measures developed in this study may provide a basis for selecting records that are capable of producing the highest structural response. Numerical verifications are provided on damage caused to structures by identified resonant records.     

论高校和谐班级及其构建

高校是和谐社会的一个组成部分是直接向和谐社会培养输送高素质人才的基地,是促进和谐社会建设的一支重要力量;班级是高校的基层组织,是实施教学、管理的重要平台,是贯彻落实学校各项工作的纽带和落脚点;和谐的高校由和谐的班级构成,构建和谐班级是构建和谐高校的基础和动力,如何寻求更好的班级构建途径,是构建高校和谐校园的一项基础工程。     

平面体波在各向异性媒质中的传播

Combining the linear transformation and the solution technique for the cubic equation,a general closed-form analyti solution for bulk waves in orthotropic anisotropic materials is obtained.This method is straightforward and general.Degenerated cases include transversely isotropic,cubic,and isotropic materials.Numerical computations are carried out on a fiber-reinforced composite plate modeled as a transversely isotropic media.The fibers are parallel to the top and bottom surfaces of the plate ,and they are rotated counterclockwise around the plate normal through different angles.The two-dimensional slowness curves corresponding to different rotations are presented graphically.The wave propagation characteristics displayed in slowness surfaces for different fiber orientation are analyzed.