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REN Kun FU Jian-zhong CHEN Zi-chen 《浙江大学学报(A卷英文版)》2007,8(12):1938-1943
To reduce mechanical vibrations induced by big errors compensation, a new software compensation method based on an improved digital differential analyzer （DDA） interpolator for static and quasi-static errors of machine tools is proposed. Based on principle of traditional DDA interpolator, a DDA interpolator is divided into command generator and command analyzer. There are three types of errors, considering the difference of positions between compensation points and interpolation segments. According to the classification, errors are distributed evenly in data processing and compensated to certain interpolation segments in machining. On-line implementation results show that the proposed approach greatly improves positioning accuracy of computer numerical control （CNC） machine tools. 相似文献
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This article is a report of a session presented by Mangala Krishnamurthy and Connie Stovall (a contributor to the presentation) of the University of Alabama Libraries at the 2015 North American Serials Interest Group conference. A patron-driven acquisition (PDA) pilot project was initiated in fall 2013 at the University of Alabama (UA) Libraries mainly serving the Nursing and Allied Health subject areas. Since the Capstone College of Nursing at UA offers an online Doctor of Nursing Practice program and partners with two other schools in the UA system, UA Libraries collaborated with the other libraries in the University System. The project uses Rittenhouse’s R2 Digital Libraries’ PDA module as the basic platform. The Capstone College of Nursing liaison discussed in detail the selection, management, assessment, promotion, and communication part of the project in addition to second year plans for the project. 相似文献
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非连续变形分析是针对非连续介质的数值计算方法。该方法存在计算效率较低的问题,而方程组求解是瓶颈。研究非连续变形分析在不同的计算条件下,选择不同的方程组求解方法可获得的计算效率。基于OpenMP与CUDA分别并行实现Jacobi迭代法与Jacobi预处理共轭梯度法,分析问题规模、计算时步长、块体接触关系对方程组求解效率的影响。通过算例测试,获得不同条件下选择方程组求解方法的经验公式,可有效指导非连续变形分析的并行方案设计。 相似文献
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付凯 《金华职业技术学院学报》2007,7(2):17-20
根据DDA插补算法的基本思想,提出了一种DDA圆弧插补改进算法,介绍了该算法的基本原理和实现算法。比较传统的插补算法,对插补改进算法的误差进行了具体的分析,结果表明DDA圆弧插补改进算法具明显的优势,可以有效提高计算精度和计算效率。 相似文献
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Eva Jurczyk Sabina Pagotto Ingrid Moisil Kalina Grewal Samuel Cassady Jacqueline Cato 《资料收集管理》2020,45(4):287-303
Abstract This paper examines the materials acquired during a consortial PDA pilot; which of the books are still being used, by which institutions, whether the size of a participating institution or the subject of a book have impact on the continued use of the books, and if there is a relationship between the schools that triggered a PDA purchase and the schools that have gone on to use a given title. Findings suggest that models involving some library mediation may be more effective in meeting the various needs of participating institutions. 相似文献
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Demand-driven acquisition (DDA) programs are playing an increasingly important role in academic libraries. However, the literature surrounding this topic illustrates the wide-ranging, and frequently unpredictable, results of DDA implementation. As uncertainty abounds, librarians continue to seek out deeper understandings of those processes driving the use and purchase of DDA materials. Implicit in this search is a desire to understand how local environmental factors and user preferences dictate broader collection use and purchasing patterns. A small number of these studies have sought deeper insights through predictive modeling, though success has been limited. Following this line of inquiry, this study explores how machine learning might enable more effective collection development and management strategies through the predictive modeling of complex collection use and purchasing patterns. This research describes a replicable implementation of an adaptive boosting (AdaBoost) model that predicts the likelihood of DDA titles being triggered for purchase. The predictive capacity of this model is compared against a more traditional logistic regression model. This study's results show that the AdaBoost model possesses much higher predictive capacity than a regression-based model informed by the same set of predictors. The AdaBoost algorithm, once trained with local DDA data, provides accurate predictions in 82% of cases. 相似文献
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[目的/意义]探讨美国图书馆需求驱动采购（DDA）的标准化发展,介绍美国国家信息标准协会（NISO）出版的《图书的需求驱动采购推荐实施规范》（NISO DDA）,为中国图书馆DDA标准化建设提供参考。[方法/过程]通过文献考察,介绍NISO DDA产生的背景、规范的制定过程、规范的要素、作用以及NISO DDA应用中面临的挑战。[结果/结论]NISO DDA为DDA走向标准化和可持续发展奠定了基础。它对保护图书馆、出版商、经销商、电子图书数据库集成商等各利益相关者的利益,以及对各方在合作共赢的基础上规范化采纳推广DDA提供指南并起到积极的作用。同时,DDA的可持续发展继续面临着挑战。图书出版链中的各利益相关者仍然为DDA的可持续发展及标准化建设积极探索。 相似文献