Mathematical Analysis of Energy Efficiency in IEEE 802.11 DCF     

高波杨宇航  马惠业 《天津大学学报(英文版)》2005,11(5):332-337

The standardized IEEE ,802. II distributed coordination function （ DCF） provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium. However, when stations are mobile or portable units, power consumption becomes a primary issue since terminals are usually battery driven. This paper proposes an analytical model that calculates the energy efficiency of both the basic and the RTS/CTS access mechanisms of the IEEE 802. II protocol. The model is validated with simulation results using NS-2 simulation package. The effects of the network size, the average packet length, the initial contention window and maximum backoff stages on the energy efficiency of both access mechanisms are also investigated. Results show that the basic scheme has low energy efficiency at large packet length and large network size, and depends strongly on the number of stations and the backoff procedure parameters. Conversely, the RTS/CTS mechanism provides higher energy efficiency when the network size is large, and is more robust to variations in the backoff procedure parameters.  相似文献   

对"效率优先、兼顾公平"分配原则的思考     

肖萍 《商丘师范学院学报》2004,20(6):121-122

效率与公平是社会经济发展的两个重要目标，社会主义的本质是效率与公平的内在统一。市场经济条件下“效率优先、兼顾公平”的分配原则有其内在统一性和客观必然性，坚持这一原则是社会主义初级阶段的现实选择。  相似文献   

基于多元线性回归分析方法的物流流通水平研究          下载免费PDF全文

潘新宇  薛洋 《唐山学院学报》2016,29(6):72-77

根据2013年全国31个省市的物流水平相关指标,分别以经营单位所在地分的进出口总额、按境内目的地和货源地分的商品进出口总额作为因变量对物流流通水平进行线性回归分析,得到了多元线性回归模型,由此找出了流通水平的影响因素,并有针对性地提出了对策建议。  相似文献   

Understanding college degree completion of students with low socioeconomic status: The Influence of the Institutional Financial Context     

Marvin A. Titus 《Research in higher education》2006,47(4):371-398

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论高校思想政治工作的务实性和有效性     

吴咏梅 《湖南科技学院学报》2006,27(12):69-70

在创建和谐社会和和谐校园的大环境下，全面掌握深刻分析学生思想现状，了解学生个性、注重个体差异是加强思想政治工作务实性、有效性的前提、基础、核心。只有适应时代发展，不断更新观念、开辟新途径、探索新方法、创造新经验，切实提升高校学生思想政治工作的务实性、有效性．  相似文献   

Differential recognition of children's cultural practices in middle primary literacy classrooms     

Helen Nixon  Barbara Comber 《Literacy》2006,40(3):127-136

This paper argues that teachers' recognition of children's cultural practices is an important positive step in helping socio‐economically disadvantaged children engage with school literacies. Based on 21 longitudinal case studies of children's literacy development over a 3‐year period, the authors demonstrate that when children's knowledges and practices assembled in home and community spheres are treated as valuable material for school learning, children are more likely to invest in the work of acquiring school literacies. However, they also show that while some children benefit greatly from being allowed to draw on their knowledge of popular culture, sports and the outdoors, other children's interests may be ignored or excluded. Some differences in teachers' valuing of home and community cultures appeared to relate to gender dimensions.  相似文献   

对跳远两种技术的初步探讨     

毛立力 《宁波教育学院学报》2002,4(1):53-55

以世界优秀跳远选手刘易斯和埃米扬的典型两跳为参照,分析了我国优秀跳远运动员在助跑速度、绝对速度、速度利用率、腾起角度与两选手之间的差异,提出了近期内练就刘易斯一样以速度见长的技术特点（低跳跃型）可能性不大的情况下,适度调整垂直速度和水平速度的比例,降低助跑速度利用率,增大腾起角,走埃米扬力量见长（高跳跃型）技术之路,是我国优秀跳远运动员提高成绩的有效途径。  相似文献   

Leveraging information and communication technologies (ICT) to enhance education equity,quality, and efficiency: case studies of Bangladesh and Nepal     

Cher Ping Lim  Sungsup Ra  Brian Chin  Tianchong Wang 《Educational Media International》2020,57(2):87-111

ABSTRACT

Information and Communication Technologies (ICT) have had significant impacts on many sectors in today’s knowledge economy. In developing and emerging countries, ICT have enhanced equity, quality, and efficiency in the education sector. However, the adoption of ICT in the South Asian countries’ education sector has not been at scale and its impacts have been limited. There are several gaps and issues that are hindering the wider adoption of ICT and limiting its impacts in the education sector. Through the case studies of the adoption of ICT for education in Bangladesh and Nepal, this paper examines the gaps and issues to be addressed in order to better leverage ICT to enhance education equity, quality, and efficiency. This discussion is guided by the ICT in the education framework that has been developed by the authors, and could provide insights into the state of ICT in education and offer strategies to better leverage ICT for the education sector of other countries in South Asia and the region.  相似文献   

论《上海屋檐下》的抒情氛围     

朱云才 《钦州学院学报》2005,20(1):64-66

作为夏衍美学思想转变后的一力作,其成功自有多方面的因素,但作品中刻意营造的情景氛围 无疑是作品获誉的一个关键,抗战前夕险恶的政治环境下小人物方方面的悲苦,生活重压下"屋檐下"住户们扭 曲了的情感生活,梅雨天带给他们的无尽的烦恼,这些共同组成该剧阴晦沉闷的情感基调,孩子们的歌声透给 这一情调丝丝的亮色。  相似文献   

提高大型贵重仪器设备使用效益的探讨   总被引：3，自引：0，他引：3  

陈达银 《实验室研究与探索》2004,23(6):83-85

如何提高大型贵重仪器设备的使用效益是高校仪器设备管理工作中面临的一个重要问题。文章结合具体实践探讨了采用经济手段,引入开放、竞争、服务新机制,通过实施有偿占用制、有偿使用制、开放基金补贴制和信息化管理等方法,提高大型贵重仪器设备使用效益的途径。  相似文献