控制系统中相关性能指标之间关系分析

本文比较详尽地推导和分析了二阶控制系统频域指标谐振频率及频宽与时域指标之间的关系，即ωr与ξ的关系、ωr与Mr的关系、ωb与ξ的关系、ωb与Mr的关系，并编写了MATLAB程序，画出了关系曲线；从而对分析和设计控制系统带来了极大的方便。     

中国画款识的几种特殊记时法

中国画时间记载的方法呈多样化,一些特殊的记时方法流传不广而少为人知。作为一个现代美术工作者,对这些特殊记时法的来源、应用方法及效果加以探讨与认识,可以对这些特殊记时法有一个全面的了解,在实践中更好地灵活应用。     

协同工作模式下的高校图书馆新型图书荐购系统建设与思考——以上海交通大学图书馆为例

[目的/意义]通过探讨多角色馆员协同工作模式下高校图书馆个性化图书荐购系统的构建与完善,为其他高校图书馆建设图书荐购系统、提升读者荐书的积极性提供参考。[方法/过程]以上海交通大学图书馆图书荐购系统建设实践为例,从传统与新型荐书系统对比、协同工作模式分析、系统设计与实现等方面出发,全面解读协同工作模式下的高校图书馆新型图书荐购系统建设实践,并对该图书荐购系统建设的实践进行思考。[结果/结论]上海交通大学图书馆通过多角色馆员协作模式,构建智能化、特色化的图书荐购系统,提高用户荐书的积极性和主动性,促进学科资源与用户需求的契合。开发一个功能丰富、荐书反馈及时的图书荐购系统有助于改善高校图书馆读者荐书的积极性。     

论全民健身与现代社会

本文论述了现代社会的迅速发展与全民健身之间的关系,全民健身的欣起与竞技体育之间的关系,以及在我国社会主义市场经济的作用下如何使体育与经济建设接轨,发挥体育的经济效益.     

MIMO离散非线性系统的自适应Backstepping控制

研究MIMO离散非线性系统的自适应Backstepping控制,对包含两个三阶子系统的MIMO系统推出稳定的自适应控制器设计,并利用关键性引理和投影算法的性质证明了闭环系统的所有信号有界和保证跟踪性能.     

Re-Envisioning E-Resource Holdings Management

For e-resource librarians, maintaining e-book and e-journal holdings within electronic resource management systems is a labor intensive and often manual process. In 2014, with the aim of saving library staff valuable time and effort, the Online Computer Library Center, Inc. (OCLC) launched a service to provide automated holdings management within the WorldCat knowledgebase. For a select group of content providers, including some of the largest e-book aggregators, holdings information can be populated and updated automatically within the knowledgebase without intervention from library staff. At the University of Toronto Libraries, we conducted a study to assess the accuracy and efficiency of these automated holdings management services. This presentation outlines the results of the study and provides suggestions for further improvement to the current services offered.     

沈从文的时间意识

沈从文的时间意识与死亡意识相生相成,构成沈从文“生命哲学”的重要而又特殊的组成部分。他认为时间的魔力巨大,能消融生命,能治疗痛苦,还能造就创作;他的时间意识停留在“过去”,具有“过去式”、“静态化”与“突变性”的特点。     

美国大学人事特点研究及启示

高校改革的关键是人事政策改革,本文通过对美国高校在选才、用才、留才等人事方面的特点进行分析和总结,以资借鉴我国高校人事政策的改革和发展。     

Inter-participant variability in daily physical activity and sedentary time among male youth sport footballers: independent associations with indicators of adiposity and cardiorespiratory fitness

Participation in youth sport is assumed to promote and contribute towards more physically active lifestyles among children and adolescents. The aim of this study was to examine inter-participant variability in objectively measured habitual physical activity (PA) behaviours and sedentary time among youth sport participants and their implications for health. One-hundred-and-eighteen male youth sport footballers (Mean ± s = 11.72 ± 1.60) wore a GT3X accelerometer for 7 days. Average daily PA [min · day^?1, in light (LPA), moderate (MPA), vigorous (VPA) and combined moderate-to-vigorous (MVPA)] and sedentary time were calculated. Participants’ body mass index adjusted for age and sex (BMI–standard deviation score), per cent body fat (BF%), waist circumference and cardiorespiratory fitness were assessed. Results revealed that variability in daily PA behaviours and sedentary time (min · day^?1) was associated with BMI–standard deviation score [VPA (?), MVPA (?)], BF% [sedentary time (+), VPA (?), MVPA (?)], waist circumference [sedentary time (+), LPA (?)] and cardiorespiratory fitness [sedentary time (?), MPA (+), VPA (+), MVPA (+)]. Whilst sedentary time and MVPA were not related to health outcomes independent of one another, associations with markers of adiposity and cardiorespiratory fitness were stronger for sedentary time. Sedentary time was also significantly positively related to waist circumference independent of VPA. Results demonstrate inter-participant variability in habitual PA and sedentary time among youth sport participants which holds implications for their health. Thus, promoting PA and, in particular, reducing sedentary time may contribute towards the prevention of adverse health consequences associated with a physically inactive lifestyle for children and adolescents active in the youth sport context.     

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach

This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.