Book industry statistics from the R. R. Bowker Company

The R. R. Bowker Company has been compiling and publishing statistics on the book industry for more than a century. The history of this effort is reported, with details on how the collection, classification, and publication of data have evolved. Bowker provides statistics on book title output, booksellers (retail and wholesale), and libraries. Jean Peters is the librarian at the Frederic G. Melcher Library, Cahners Publishing Company, formerly the library of the R. R. Bowker Company.     

Alternative technologies and social studies textbooks

In order to determine the potential of alternative technologies in social studies education, we must understand the goals of such education, the capabilities of the technologies, and teachers’ and students’ responses to new technologies. The author suggests that the new technologies can contribute to the goals of learning about the past, learning about democratic life and institutions, and making students knowledgeable as consumers and producers of information. One major obstacle is a lack of time and money for teachers to experiment with the technologies. Stephen T. Kerr is professor of education in the College of Education at the University of Washington. His research focuses on the application of new technologies in schools and other educational environments, and particularly on the ways in which technology affects the social structure (roles and expectations, instructional patterns, organization) of those institutions. He has done work on human-computer interaction, as well as on how new communication technologies have changed the educational system of the former USSR.     

三维影相的新算法——修正的直接线性变换

通过引入摄影机镜头的内、外方位元素的约束条件,导出了一种修正的DLT(MDLT)方法。该方法用于影片和录相的实测,得到一些有意义的结果。当测量的标定控制点点数较少(6～8个),且这些点的位置在空间和成像面分布不均匀时,用MDLT计算的结果比DLT的结果要好,误差可降低80％以上。     

Assessing the Utility of Item Response Models: Computerized Adaptive Testing

How has Item Response Theory helped solve problems in the development and use of computer-adaptive tests? Do we need to balance item content with computer-adaptive tests? Could we use IRT to evaluate unusual responses to computer-delivered tests?     

数字图书馆的研究内容和方向

在我国 ,数字图书馆的研究和建设 ,必须鼓励跨学科的合作和国际合作 ;国家的资助要保持数字图书馆项目 (研究类、应用类和内容建设类 )间的平衡 ;要从具体的应用环境出发 ,建设有特色的数字图书馆 ,不能盲目追求大、全、新 ;应重视元数据的研究。参考文献 1。表 4。