Methodological Choices in the Content Analysis of Textbooks for Measuring Alignment With Standards

With the recent adoption of the Common Core standards in many states, there is a need for quality information about textbook alignment to standards. While there are many existing content analysis procedures, these generally have little, if any, validity or reliability evidence. One exception is the Surveys of Enacted Curriculum (SEC), which has been widely used to analyze the alignment among standards, assessments, and teachers’ instruction. However, the SEC can be time‐consuming and expensive when used for this purpose. This study extends the SEC to the analysis of entire mathematics textbooks and investigates whether the results of SEC alignment analyses are affected if the content analysis procedure is simplified. The results indicate that analyzing only every fifth item produces nearly identical alignment results with no effect on the reliability of content analyses.     

创建neighbor-joining进化树的快速算法

为了改善Saitou和Nei提出的neighbor-joining进化树算法(SN)及Studier和Keppler的改进算法(SK),降低计算的时间复杂度,设计了一种快速算法.该算法涉及3种技术第一,引入一个线性数组A[N],用于存储距离矩阵每一行的值,以减少许多重复计算;第二,A[i]的值在算法开始时全部计算,在迭代步中间只进行更新3个变化的值;第三,设计了一个紧凑的公式用于计算OTUs之间的边长,并对该公式进行了证明.实验结果表明随着节点数的增多,该算法比SN算法快几十倍到上百倍,比SK算法快2倍以上;在一台桌面计算机上,该算法能在3min左右创建具有2000个节点的进化树.以空间换时间,减少最内层循环的计算量是设计多重循环算法的基本思路.     

传递对准中基准信息时间延迟的估计与补偿

针对传递对准过程中基准信息时间延迟对传递对准精度的影响,给出了一种基于角速率积分最小方差曲线拟合的时间延迟估计方法.首先,记录一段时间内主、子惯导陀螺传感器的输出数据,并对该数据进行积分.然后,定义基准信息可能存在的时间延迟的最大范围,并在该范围内对主惯导数据进行逐点移位,计算曲线各对应点的差的平方并求和.最后,通过最...     

物体表面不同角度采集的三维图像配准的一种新算法

提出了一种能有效实现物体表面三维图像数据配准的算法.该算法利用了三维数据采集时的三维点的阵列信息,这些三维点的阵列信息在采集原始三维数据时可以很容易获得,同时,还利用了三维数据矢量/顶点相似特征作为数据匹配的基础.采用迭代最小均方误差算法来自适应优化变换矩阵参数.这些方法可以有效地提高三维图像配准的性能,加快匹配过程的运算速度.实验结果表明该算法可以获得较好的配准后三维图像的主观效果.尽管该方法主要针对人头模型,但经过少许修改后即可适用于其他物体.     

玻色--爱因斯坦凝聚--2001年诺贝尔物理奖评介

评介了实现玻色-爱因斯坦凝聚的物理思想、可能应用和进展.     

美国“SEC”一致性分析范式的诠秤与启示——基础教育中评价与课程标准一致性的视角

美国在基于课程标准的教育改革以及学校教学要求偏低的现实背景下，致力于研制“SEC”（Surveys of Enacted Curriculum）等一致性分析范式，即分析评价与课程标准一致性程度的理念、程序和方法，推动了美国学校基于课程标准的评价实践。该范式对我国课程评价的启示在于：要认识到评价与课程标准一致性策略是调适课程运行偏差的重要手段；要立足本土化，研制评价与课程标准一致性分析的程序和方法。     

Controllable high repetition rate gain-switched Nd:YVO4 microchip laser

We demonstrated a monolithic, compact, diode-pumped gain-switched Nd:YVO4 laser at 1.064 μm wavelength with controllable repetition rate of 1 Hz to 25 kHz. Stable gain-switched pulse train with maximum repetition rate of 25 kHz and pulse width of 16 ns was obtained.     

唱好高音的几个重要因素

基于专业教学经验的总结，对唱好高音的问题提出了自己的看法，认为唱好高音必须运用采取的方法是：真正打开喉龙；正确运用气息；声音“走向”正确无误；科学运用混合共鸣等。     

Building parallel corpora by automatic title alignment using length-based and text-based approaches

Cross-lingual semantic interoperability has drawn significant attention in recent digital library and World Wide Web research as the information in languages other than English has grown exponentially. Cross-lingual information retrieval (CLIR) across different European languages, such as English, Spanish, and French, has been widely explored; however, CLIR across European languages and Oriental languages is still in the initial stage. To cross language boundary, corpus-based approach is promising to overcome the limitation of the knowledge-based and controlled vocabulary approaches but collecting parallel corpora between European language and Oriental language is not an easy task. Length-based and text-based approaches are two major approaches to align parallel documents. In this paper, we investigate several techniques using these approaches and compare their performances in aligning English and Chinese titles of parallel documents available on the Web.