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71.
何少钧 《陕西理工学院学报(社会科学版)》2003,21(1):53-56,67
通过对中美男篮比赛技术指标的比较分析,研究了中国男篮与美国男篮在防守效率、投篮效率、进攻效率等比赛效率方面的实际状况。针对我国男篮的现状与不足,提出了在今后训练中改进和加强的建议,旨在为中国男篮科学训练提供参考依据。 相似文献
72.
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
73.
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
74.
75.
韩桂兰 《中国教育研究与创新》2005,2(12):20-21
本文主要论述了自然扬尘污染、水资源污染、土地资源的污染对新疆城市环境和生态环境的危害和造成的直接影响,最后提出了解决新疆城市环境与生态问题。 相似文献
76.
于丽 《大连教育学院学报》2006,22(3):40-41
批评是学校教育最常用的方法之一,但这一方法如使用不当则收不到好的效果。教师在批评学生时应讲究批评的艺术,要慎用批评,善用批评,巧用批评。 相似文献
77.
The ubiquity and educational potential of mobile applications are well acknowledged. This paper proposes six theory-based, pedagogical strategies to guide interaction design of mobile apps for young children. Also, to augment the capabilities of mobile devices, we used a humanoid robot integrated with a smartphone and developed an English-learning app that applied the design strategies to this environment. Our observations of children's one-on-one use support the promise of the strategies and the combined use of robots and mobile devices to be a viable option to help optimize mobile learning. 相似文献
78.
Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system 总被引:2,自引:0,他引:2
Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using
advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The
working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model.
Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as
poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was
conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera.
The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good
agreement with the numerical result.
Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for
Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097) 相似文献
79.
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
80.
INTRODUCTION Dynamics of carbon and water vapor fluxesexchange between the atmosphere and the ecosystembiosphere, depend on complex and non-liner interplayamong physiological, ecological, biochemical andedaphic factors and meteorological conditions (Jarvis,1995; Leuning et al., 1995). There are many studiesquantifying the fluxes across different time and spacescales as well as assessing the environment con-straints on them by some kinds of biophysical orempirical models whose resul… 相似文献