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排序方式: 共有58条查询结果,搜索用时 390 毫秒
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Wireless Networks - In such mobile platforms as ships and aircraft, the detection and reconnaissance devices are near to the communication facilities. When working at the same time, they will... 相似文献
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为了缓解无小区大规模MIMO系统的导频干扰、提高系统性能,提出了一种综合导频复用、AP选择和功率控制的导频干扰抑制策略。首先,提出了基于用户距离排序的导频分配,合理地避免了两个距离较近的用户复用导频,以减少导频干扰的影响。然后,通过分析系统吞吐量表达式中的影响因子确定AP选择的标准,只选择对用户的宏分集增益有主要影响的AP作为用户的服务AP。最后,提出了一种改进的最大最小功率控制算法,提高系统平均吞吐量。仿真结果显示,提出的导频干扰抑制策略有效地减轻了导频干扰带来的性能损失。 相似文献
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大环抗生素--毛细管电泳手性分离中一种新的手性选择剂 总被引:3,自引:0,他引:3
两种类型的大环抗生素对很多外消旋化合物具有显著的手性选择性且手性选择性相互补充:第一种类型含ansamycin (安沙霉素) 特别适合于阳离子外消旋化合物的分离;第二种类型含glycopeptide (糖肽)最适于阴离子的分离.介绍了大环抗生素的结构特征及手性识别机理,讨论了pH值、抗生素类型和浓度、电泳电解质浓度和化学性质、有机改性剂及胶束相等不同实验条件对分离的影响,还概述了几种大环抗生素作为手性选择剂,在毛细管电泳手性分离中的研究近况. 相似文献
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Zhao Chenglin Xu Fangmin Sun Xuebin Sun Songlin Jiang Ting Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Network Lab Beijing University of Posts Telecommunications Beijing P. R. China Samsung China Communication R&D Center Beijing P. R. China 《中国通信》2010,7(2):109-116
The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communication of primary system operated in the same frequency band. In this work, the problem of the capacity analyses of cognitive UWB networks is investigated. Different from the conventional cognitive spectrum sharing model which can only utilize the idle spectrum hole, the cognitive UWB system can... 相似文献
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Direct Determination of Trace Dopamine in an Ascorbic Acid Solution at a Bare Glassy Carbon Electrode Using Differential Pulse Voltammetry 下载免费PDF全文
Lijian Sun Jing Chen Fangmin Zhao Na Liu Yingqiu Zhang Jianbo Jia Jianguo Wang 《Electroanalysis》2015,27(6):1411-1415
It is difficult to monitor dopamine (DA) accurately with a bare glassy carbon electrode because of the interference of ascorbic acid (AA). In this paper, a method for the determination of DA in an AA solution using differential pulse voltammetry was established. Because AA loses its electrochemical activity after being oxidized, hydrogen peroxide was used to oxidize AA, and the interference of AA was completely eliminated. As a result, trace DA could be directly determined in the AA solution with a bare glassy carbon electrode. When trace DA was determined in a 1.0 mmol L?1 AA solution, there was a wide linear range from 3.0×10?8 mol L?1 to 1.0×10?5 mol L?1. The application of this method was demonstrated by the selective measurement of DA in an injection without pretreatment. 相似文献
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大规模MIMO系统中由于系统下行链路的迫零(zero forcing,ZF)预编码中存在大矩阵求逆运算,随着用户数与天线数的增加,其复杂度随之增加。为了降低复杂度,提出了一种基于雅克比(Jacobi)迭代算法的改进预编码算法,用下二对角矩阵作为迭代矩阵,并且将迭代结果与上一步迭代结果进行权重相加来加速迭代。根据大规模MIMO系统信道矩阵的对角占优特性,将矩阵求逆的诺依曼近似的第一项作为迭代的初始值进一步加速迭代。相比于传统迫零预编码方案,提出的方案可以降低一个量级的算法复杂度,并且保证了预编码方案的性能。 相似文献
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A new and green liquid–liquid microextraction method based on a switchable hydrophilicity solvent for the determination of 11 drugs in urine is presented for the first time. The protonated N,N-dimethylcyclohexylamine was used as an extraction solvent and sodium hydroxide was injected as a trigger for organic-phase separation. The extraction procedure has been optimized and investigated in this study. The intraday and interday recovery ranged from 73.8 to 103.0% and the relative standard deviations were in the range from 2.2 to 13.5% (n?=?5). The linear range was from 5.0 to 2000.0 µg L?1, and R2 was greater than 0.99, and the limit of detection was in the range from 0.36 to 12.50 µg L?1. The proposed method may be a useful procedure for the determination of 11 drugs in urine, and easily incorporated into routine testing for a laboratory. 相似文献
Graphical Abstract
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