Binary Interpolative Coding for Effective Index Compression

Information retrieval systems contain large volumes of text, and currently have typical sizes into the gigabyte range. Inverted indexes are one important method for providing search facilities into these collections, but unless compressed require a great deal of space. In this paper we introduce a new method for compressing inverted indexes that yields excellent compression, fast decoding, and exploits clustering—the tendency for words to appear relatively frequently in some parts of the collection and infrequently in others. We also describe two other quite separate applications for the same compression method: representing the MTF list positions generated by the Burrows-Wheeler Block Sorting transformation; and transmitting the codebook for semi-static block-based minimum-redundancy coding.     

通向自由的艰难之路——我国开放存取的现状分析

目前,多数研究误将我国开放存取发展缓慢的原因归结为知识产权对开放存取的威胁、质量控制的制约、付费模式脱离实际等因素.实质上,政府、机构、期刊和研究者对开放存取的认知度过低才是问题的关键.基于问题的核心因素,我国开放存取的发展需要政府采取有效的措施加以引导、机构的认可与重视、学术期刊的积极参与、研究者的支持.     

Facilitating learning in large lecture classes: testing the "teaching team" approach to peer learning

We tested the effect of voluntary peer-facilitated study groups on student learning in large introductory biology lecture classes. The peer facilitators (preceptors) were trained as part of a Teaching Team (faculty, graduate assistants, and preceptors) by faculty and Learning Center staff. Each preceptor offered one weekly study group to all students in the class. All individual study groups were similar in that they applied active-learning strategies to the class material, but they differed in the actual topics or questions discussed, which were chosen by the individual study groups. Study group participation was correlated with reduced failing grades and course dropout rates in both semesters, and participants scored better on the final exam and earned higher course grades than nonparticipants. In the spring semester the higher scores were clearly due to a significant study group effect beyond ability (grade point average). In contrast, the fall study groups had a small but nonsignificant effect after accounting for student ability. We discuss the differences between the two semesters and offer suggestions on how to implement teaching teams to optimize learning outcomes, including student feedback on study groups.     

Evaluating students’ perceptions and attitudes toward computer-mediated project-based learning environment: A case study

This research investigated 68 secondary school students’ perceptions of their computer-mediated project-based learning environment and their attitudes towards Project Work (PW) using two instruments—Project Work Classroom Learning Environment Questionnaire (PWCLEQ) and Project Work Related Attitudes Instrument (PWRAI). In this project-based learning environment, students experienced a face-to-face classroom setting and e-learning by using a synchronous computer-mediated communication (CMC) tool called ‘iCollaborate’ for online communication and project collaboration with peers from other countries. The PWCLEQ and PWRAI instruments were used to evaluate the computer-mediated project-based learning environment using students’ perceptions of the learning environment and to further investigate how their perceptions might affect their attitudes towards PW lessons. Students perceived the computer-mediated project-based learning environment favourably but they preferred to experience more Material Environment and more Open-Endedness and Social Presence. Simple correlation analysis revealed that all environment dimensions were significantly and positively related to the students’ attitudes towards PW, while multiple regression analysis indicated that two scales, Instructor Support and Social Presence, were the strongest predictors of attitudes towards PW lessons.     

我国农民体育消费的现状与对策研究

体育消费已成为我国拉动内需、活跃市场、繁荣经济、拓宽就业渠道的一支坚挺力量。研究约占全国人口总数70%农民的体育消费状况将对我国整体经济发展和社会主义新农村建设有着重要的划时代的历史意义。通过对我国发达与欠发达地区农民体育消费现状进行了调查和分析,并提出对策与建议,旨在落实＂农民体育健身工程＂,推动农村体育市场的建立与发展,改变农民的消费意识,拉动新农村经济的增长,促进社会主义新农村建设。     

河池学院校园鸟类初步调查

2008年7月至2009年7月,采用样线调查和随机观察的方法对河池学院校园的鸟类进行了初步调查。在这次调查中,共记录到鸟类101种,隶属于12目32科。其中留鸟54种,夏候鸟10种,冬候鸟26种,旅鸟11种。校园鸟类以食虫鸟类为主,达64种,约占鸟类种数的63.4%;食果鸟类16种,约占鸟类种数的15.9%。在4种生境类型中,在残留林活动的鸟类种数最多,达62种,约占校园鸟类种数的61.4%。在水域中活动的鸟类仅18种,约占校园鸟类种数的17.8%。同时,也对校园鸟类的保护提出建议。     

BD-2/GPS组合导航系统选星算法及定位分析

为解决组合导航系统定位精度与快速定位之间的矛盾,提出一种新的选星算法.该方法将可见卫星仰角与遗传算法相结合,以几何精度因子(GDOP)计算模型作为遗传算法中判断解优劣的适应度函数,从而达到快速定位的效果.将应用该方法所得的GDOP和算法运行时间与应用最佳GDOP算法计算所得的相应结果进行对比,发现采用该方法得到的GDOP接近最优值,而且选星算法计算时间减少.实验数据分析证明该方法在实时性和可行性方面的优越性.     

浅谈建设工程合同前期管理及人的重要性

我国从社会主义计划经济缓慢转变为市场经济,从某一方面说,也意味着向合同经济的转变。在建筑业中,合同管理即核心。建设工程合同是双方履行义务,享有权利的法律基础。建筑企业想要谋取更多的利润,规避更多的风险,就应该重视合同前期的管理及管理型技术人才的培养,通过管理能力的提升来减少争议和纠纷,从而降低成本。     

Erratum to: Transmission risk of patients with COVID-19 meeting discharge criteria should be interpreted with caution

Journal of Zhejiang University-SCIENCE B - The original version of this article unfortunately contained a mistake. For Fig. 1a in p.409, the citation of a reference, as well as the permission to...