Power control scheme for multiple antenna systems with space-time coding in Rayleigh fading channels

Two optimal power control(PC) schemes under the power constraint for space-time coded multiple input multiple output systems over the flat Rayleigh fading channel with the imperfect channel state information(CSI) are presented.One is based on the minimization of a bit error rate(BER),and the other is based on the maximization of a fuzzy signal-to-noise ratio.In these schemes,different powers are allocated to individual transmit antennas rather than equal power in the conventional one.For the first scheme,the optimal PC procedure is developed.It is shown that the Lagrange multiplier for the constrained optimization in the power control does exist and is unique.A practical iterative algorithm based on Newton’s method for finding the Lagrange multiplier is proposed.In the second scheme,some existing schemes are included,and a suboptimal PC procedure is developed by means of the asymptotic performance analysis.With this suboptimal scheme,a simple PC calculation formula is provided,and thus the calculation of the PC will be straightforward.Moreover,the suboptimal scheme has the BER performance close to the optimal scheme.Simulation results show that the two PC schemes can provide BER lower than the equal PC and antenna selection scheme under the imperfect CSI.     

论西藏农牧区学校体育现状及发展对策研究

文章通过对西藏农牧区中小学学校体育场地、器材现状、体育师资队伍现状、体育教学大纲的落实现状、学校课外体育活动的开展现状等进行调查和分析研究。提出了农牧区中小学学校体育的发展对策及建议。     

浅谈音乐在体育教学中的应用

随着体育新课程标准的实施,音乐已在学校体育教学中广泛应用,得到了广大体育教师的重视。音乐与体育有着密切的联系,通过分析音乐与体育在人的心理和生理上的关联作用,在体育教学中采取适当的音乐来辅助教学,可以有效的达到将音乐融入体育教学的目的。体育教学要充分利用音乐的韵律、节奏、艺术的美感,有效调动学生的积极性,激发对运动美的追求。对提高兴奋性,帮助学生学习体育知识,提高技术、技能,消除运动疲劳有很大帮助。音乐衬托体育,体育表现音乐,体育和音乐相辅相成。因此,把音乐引入体育与健康课堂具有非常重要的意义。     

视网膜图像中视盘的快速自动定位方法

基于眼底视网膜血管的分布结构及视盘本身的特点,提出一种快速自动定位视盘的方法.首先根据视网膜血管的网络分布结构大致定位视盘的垂直坐标:然后根据视盘的亮度信息及视盘与血管的关系来定位视盘的水平坐标;最后把视盘限定在以粗定位的视盘为中心的一个小窗口内,用Hough变换精确定位视盘中心.该方法不需要事先分割视网膜血管,也不需...     

独特的学术视野 科学的研究方法——简评《煤殇———煤矿安全的社会学研究》兼论安全社会学的构建与发展

对颜烨教授的新作《煤殇——煤矿安全的社会学研究》中的理论视野和研究方法进行了分析,回顾了安全社会学创立和发展的过程,并对安全社会学的未来发展提出了建议。     

我国铁路空调客车车外空气参数确定的方法研究与探讨

笔者在认真分析影响我国铁路空调客车空调调节品质的主要因素的基础上,对如何提高我国铁路空调客车的空调装置的使用效率的问题进行了研究,并重点对空调客车车外空气参数确定的方法研究与探讨,并得到了适合我国铁路空调客车使用的外气参数的经验值。     

Path probability for a Brownian motion

This work reports on numerical simulations of Brownian motion in the non-dissipative limit. The objective was to prove the existence of path probability and to compute probability values for some sample paths. By simulating a large number of particles moving from point to point under Gaussian noise and conservative forces, we numerically determine that the path probability decreases exponentially with increasing Lagrangian action of the paths.     

Direct C(sp2)-H chlorination of ketene dithioacetals using FeCl3 as the chloride source and PhI(OAc)2 as an oxidant

The oxidant iodosobenzene diacetate was combined with the cheap,environment-friendly FeCl3 as a chloride source to produce an efficient chlorinating agent for α-chlorination of ketene dithioacetals through direct C(sp2)-H chlorination.Furthermore,the synthetic utility of α-chlorinated ketene dithioacetals was verified by the intermolecular cyclization with hydrazine hydrate,leading to the synthesis of pyrazoles,in which a 1,2-sulfur migration was involved.     

Measurement of the absorption spectrum of H2O+ in the visible region

Together with the 74 lines belonging to (0,9,0)- (0,0,0) band, the high-resolution absorption spectrum of H₂O⁺ A²A₁-X²B₁ system was observed in the visible region of 16680 — 17300 cm^-1 using optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy for the first time, which verifies the high sensitivity and high signal to noise ratio (S/N) of this technique.     

排舞运动对不同年龄段女性健身效应研究

排舞是当代社会较为流行的一种舞蹈形式.适合不同人群,尤其是不同年龄段的女性.文章分析了排舞的基本概念与特征,通过比较分析法、年龄分析法以及一定调查实验的基础上,分3个年龄段：少年、青年、中老年,对排舞运动对不同年龄段女性健身效应进行分析归纳,以期促进排舞运动的普及,对女性的身心健康起到积极意义.