Radical Relocation: Adapting Print Collections to an E-Centric World

With the advent of e-journal preservation projects and publisher digitization of journal backfiles, academic libraries have begun to move their corresponding print volumes of these titles to storage to avoid duplication and save space. This article examines the supporting justifications, outreach mechanisms, and logistical procedures undertaken at American University Library to relocate the entire bound journal collection to offsite storage in order to address severe physical space constraints and to support patron use of and preference for electronic journal content. In addition, the article presents preliminary data regarding the use of bound volumes sent to storage and an overall analysis of this transformational project.     

The Dark Side of Collection Management: Deselecting Serials from a Research Library's Storage Facility Using WorldCat Collection Analysis

To address the situation of its nearly full storage facility, the Purdue University Libraries developed guidelines for the deselection of very low–use serial titles and conducted a pilot project to identify material for withdrawal. The library school intern hired to conduct the pilot used WorldCat Collection Analysis to create subject lists of titles to be considered for withdrawal. These lists also contained value-added information about how many benchmark institutions owned and duplicated the local holdings of each title. Working with subject specialists, the intern developed criteria to guide a major serials deselection project. After the success of the internship in six subject areas, the libraries funded a longer-term position to complete the deselection project.     

The Development and Management of a University Microforms Collection

Microforms emerged as a major means of acquiring library resources during the '60s, and libraries acquired a large number of titles in this format. The management of these materials was frequently neglected, however. Further growth in the '70s increased the need for their control. The development and growth of the University of Oklahoma Libraries Microforms Area is described, and reasons for managerial decisions are provided. Construction of a new building led library personnel to design a new Microforms Area with a user-friendly atmosphere. Factors contributing to the successful use of microforms and the need to continue to develop and maintain microform collections are discussed.     

Modelling the lifetime of colour photographs in archival collections

Abstract

Colour photographs are among the most vulnerable materials in archival collections, making the development of tools for assessment of their lifetime in storage of particular interest. However, for this to be possible it is necessary to have a holistic understanding of what affects the lifetime of an object. Based on the existing knowledge of the effect of environmental conditions and material properties on lifetime of prints, this work focuses on the determination of end-of-lifetime using a value-based psychophysical approach. This research, carried out using a series of stakeholder workshops, showed that while assessor background does not significantly affect the end-of-lifetime determination, the nature of the images does. Isochrones, curves linking points of equal lifetime at paired environmental conditions, are defined. Based on these, a practical photographic lifetime calculator is presented, integrating dose-response functions with end-of-lifetime considerations. This tool, based on stock modelling principles, allows collection managers to input material stability data about the chromogenic prints in their collection and then investigate the effect of environmental scenarios on the collection. A case study of a collection at The National Archives, UK is also presented.     

蓄电池双向高频充放电装置研究

蓄电池双向高频充放电装置在储能中应用广泛,成为近年来研究的热点。该装置由双向高频半桥DC-DC拓扑电路和PWM整流器构成。介绍了该装置的组成及原理,对双向高频半桥DC-DC拓扑和控制方式,以及PWM整流器的控制部分进行了分析,最后得出基于实验平台的相关波形。     

数字图书馆资源云存储模型研究

文章在介绍云存储的相关概念及独特优势的基础上,将云存储引入数字图书馆资源存储中,构建了从体系结构、拓扑结构及功能模块三方面的数字图书馆资源云存储方案,指出了云存储在存储安全及图书馆知识产权方面的缺陷。     

知识存取：内涵、特征及其量素

论述图书馆的本质特征是知识存取。知识存取具有系统性、动态性、增值性特征。知识存量是知识增长的静态表征,是系统在特定时点的知识储备水平,反映知识的组织状况和供应能力;知识取量是知识的动态表征,是系统在特定时段的知识流动总量,反映知识的扩散速度和水平;知识质量是知识内在质的规定性,是系统知识现实与潜在价值的总和,反映知识的直接效用和耐用程度;知识变量是知识在存取中的变化值,是系统知识的变化总量,反映知识在存取中转化的程度。知识存取,正是要努力地实现客观知识朝着理想的增函数曲线方向变化。     

环境温度对RE(NiCoMnAl)_5贮氢合金电化学性能的影响

对LaxCe0 .9-x(PrNd) 0 .1 (Ni3 .5 5 Co0 .75 Mn0 .4Al0 .3)合金 (x =0 .4～ 0 .9)在不同温度下( 2 98K～ 333K)的电化学性能进行了系统的研究 .结果表明 ,随着温度由 2 98K升高到 333K ,合金的活化性能得到改善 ;合金的最大放电容量增大 ,并在 313K时达到最大值 (平均提高了 2 2 .9mAh/g) ,而当温度提高到 3 33K时 ,各合金的最大放电容量又大幅度下降 (平均降低了 83 .9mAh/g) ;随着温度的升高 ,合金的高倍率放电性能得到改善 ,但合金的循环稳定性明显降低 (在 1C充放电电流下经2 2 0次充放电循环后的容量保持率平均降低了 4 0 %以上 ) .     

直接接触式换热技术及其在蓄冷中的应用

介绍了直接接触式换热的特点 ,综述并分析了直接触式换热在蓄冷中的应用研究状况 ,指出了存在的问题及其努力的方向 ,最后介绍了上海理工大学有关直接接触式蓄冷技术的研究状况。     

肾脏保存中亚细胞水平上Ca2+浓度的X射线微区分析

应用定量 X射线微区分析技术结合细胞化学技术 ,分析测定用单纯冷冻法保存离体猫肾脏过程中肾脏细胞的胞浆、线粒体、内质网、细胞核等细胞器内的 Ca2 浓度变化 ,并探索钙通道阻滞剂对这种变化的影响 .保存 36h及 72 h后 ,线粒体与胞浆中 Ca的峰背比极显著地提高 ,内质网、细胞核中 Ca颗粒减少 .添加 Verapamil后 ,保存过程中细胞器内 Ca2 无显著变化 .线粒体中的Ca峰背比与胞浆中的呈强的正相关 ,r=0 .990 .实验结果揭示 :保存过程中 ,Ca2 由 Ca库 (内质网等 )进入胞浆中 ,线粒体在胞浆 Ca2 浓度高时摄取 Ca2 ,而钙通道阻滞剂可抑制该过程