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Search Results: 1 - 10 of 136867 matches for " 徐伟 "
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浅析南京地铁盾构进出洞区土体的加固技术
Analysis the in and out of the Hole Region’s Soil Reinforcement Technology of the Nanjing Subway Shield
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Open Journal of Transportation Technologies (OJTT) , 2013, DOI: 10.12677/OJTT.2013.22020
Abstract:
本文详细阐述了盾构法隧道在进出洞区土体加固的各种技术,介绍了南京地铁盾构进出洞区土体加固的常用技术,并对他们从多个角度进行了对比分析,对加固技术的选择提供一定的参考依据;结合前人的研究成果,对进出洞区的纵向和横向加固范围进行了归纳总结;最后介绍了南京某一盾构区间运用素钻孔灌注桩加双管旋喷桩和降水技术来进行土体加固的工程实例,论证了该加固技术的可行性,确保了盾构的成功始发和到达,对今后的类似工程具有一定的指导意义。
This paper describes the shield tunnel’s in and out of the hole region’s soil reinforcement technologies, and introduces a common technique for soil reinforcement of Nanjing subway shield’s in and out of the hole region, and gives them a comparative analysis from multiple perspectives. To provide a reference basis for selection of reinforcement technology, by combining with the results of previous studies, it summarizes the in and out of the hole area’s longitudinal and transverse reinforcement range. Finally, it introduces a soil reinforcement project example of a Nanjing shield zone which used the bored pile, double-barreled churning pile and lowering technologies, and demonstrates the feasibility of this reinforcement technology which ensures the success of originating and reach of the shield. This study will have a certain guiding significance of the similar projects in the future.
TAS/STBC系统在n-Rayleigh信道下的性能分析
Performance Analysis of TAS/STBC Systems under n-Rayleigh Fading Channels
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Open Journal of Circuits and Systems (OJCS) , 2014, DOI: 10.12677/OJCS.2014.33007
Abstract:
在n-Rayleigh信道下,研究了使用发射天线选择(TAS)和正交空时分组码(STBC)的多输入多输出(MIMO)系统的平均符号误码率(ASEP)性能。基于标量加性高斯白噪声(AWGN)信道的方法,得到了系统使用多进制正交幅度调制(MQAM)和多进制相移键控调制(MPSK),在接收端的信噪比的表达式。然后对不同条件下的ASEP性能做了数值仿真,仿真结果表明:随着发射天线或接收天线数的增加,系统的ASEP性能得到了很好的改善,当使用QPSK调制,SNR = 12 dB,(3,3; 6)系统的误码率是2 × 10?3, (4,4; 8)系统的误码率是2 × 10?4, (5,5; 10)系统的误码率是2 × 10?5
The average symbol error probability (ASEP) of multiple-input multiple-output (MIMO) systems employing transmit antenna selection (TAS) and orthogonal space-time block code (STBC) under n-Rayleigh fading channels is investigated in this paper. Based on the scalar additive white Gaus-sian noise (AWGN) channel approach, the exact form expressions of the signal-to-noise ratio (SNR) at the receiving end are derived for multiple quadrature amplitude modulation (MQAM), and mul-tiple phase shift keying modulation (MPSK). Then the ASEP performance under different conditions is evaluated through numerical simulations. Simulation results show that: the ASEP performance can be improved with the increase of the number of transmit antennas or receive antennas, when SNR = 12 dB, the ASEP of (3,3; 6) with QPSK is 2 × 10?3, (4,4;8) is 2× 10?4, (5,5; 10) is 2 × 10?5.
TAS/STBC系统在相关Rayleigh信道下的性能分析
Performance Analysis of TAS/STBC Systems over Correlated Rayleigh Fading Channels
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Applied Physics (APP) , 2014, DOI: 10.12677/APP.2014.45010
Abstract:

针对相关Rayleigh信道,研究了使用发射天线选择(TAS)和正交空时分组码(OSTBC)的多输入多输出(MIMO)系统的平均符号误码率(ASEP)性能。首先采用了非常适合室内信道的Laplacian模型,得到了两个天线之间的相关系数,它是天线间隔,功率方位角谱(PAS)的标准差和平均到达角(AOA)三者的函数。然后引入了相关矩阵,建立了TAS/STBC系统的相关信道模型,基于等效的标量加性高斯白噪声(AWGN)信道的方法,得到了系统在接收端信噪比的表达式。最后对不同条件下的系统的平均符号误码率(ASEP)性能做了仿真,仿真结果表明:TAS/STBC系统的ASEP性能受到空间相关性的影响,尤其是天线间隔,功率方位角谱(PAS)的标准差和平均到达角(AOA)三者的影响。
The average symbol error probability (ASEP) of multiple-input multiple-output (MIMO) systems employing transmit antenna selection (TAS) and orthogonal space-time block code (OSTBC) over correlated Rayleigh fading channels is considered. We first derive the correlation coefficients between two antenna elements as a function of the antenna spacing, the standard deviation of the power azimuth spectrum (PAS) and the mean angle of arrival (AOA) for the truncated Laplacian model, which is appropriate for indoor channels. Then we introduce the correlation matrix, and establish a correlated channel model. Based on the equivalent scalar additive white Gaussian noise (AWGN) channel approach, the exact form expressions of the signal-to-noise ratio (SNR) at the receiving end are derived. The system performance under different conditions was evaluated through numerical simulations. Numerical results show that: the ASEP performance is affected by the spatial correlation, which varies according to the antenna spacing, PAS standard deviation and mean AOA.

一个三角不等式的衍生不等式
A New Inequality Derivates from a Classical Triangle Inequality
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Pure Mathematics (PM) , 2014, DOI: 10.12677/PM.2014.41004
Abstract: 本文通过对经典三角分式不等式“若\"\",则有\"\"”的代数推广,得到了两组较新的不等式,在证明的过程中充分用到了基本不等式和数学分析的技巧。
In present paper, we derived two new inequalities from a classical triangle fractional inequality “if\"\" , then\"\" ”, by use of the fundamental inequality and mathematical analysis techniques.
X射线显微分析法及其在生物学医学中的应用

生物化学与生物物理进展 , 1981,
Abstract:
CCD不均匀性校正

红外与毫米波学报 , 1987,
Abstract: 研制了CCD不均匀性校正系统,实现了通常校正中忽略的暗电流不均匀性的实时校正。不均匀性校正精度为1.7%,系统由硬件实现,工作频率达10MHz以上。讨论了系统的校正原理、实现方法和设计思想。用校正后的系统进行了测量实验,得到了较好的实验结果。
社区老年人跌倒伤害危险因素分析

环境与职业医学 , 2010,
Abstract: :[目的]分析社区老年人跌倒的危险因素,为政府及相关部门制定干预措施提供科学依据。[方法]采用概率与规模成比例抽样方法,在某街道随机抽取60岁以上老年居民1967人为跌倒回顾性调查对象,在单因素分析结果的基础上应用Logistic多因素分析致使老年人跌倒的危险因素。[结果]在1967名调查对象中,跌倒伤害发生率为2.54%;其中男性跌倒发生率为1.68%,女性跌倒发生率为3.35%。单因素分析表明,年龄、性别、视力状况、有无慢性疾病、步态水平等与老年人跌倒有相关(P<0.05)。Logistic多因素分析表明,女性、年龄75岁以上、文盲、无配偶、睡眠质量差、视力差、患有两种及以上慢性病、室内存在危险环境和步态异常等9个因素是社区老年人跌倒的主要危险因素(OR>1,P<0.05)。[结论]社区老年人跌倒受多种因素影响,应立足于预防。
水晶彩鲫、红鲫、锦鲤、荷包红鲤杂交子代的生长和体色研究

水产学报 , 2005,
Abstract: 利用人工授精的方法,进行水晶彩鲫、红鲫、锦鲤和荷包红鲤的相互杂交试验,测定各个杂交组合子代的成活率、生长速度和体色分离比例.结果表明:4种鱼能够相互杂交受精,孵出鱼苗.孵化率锦鲤自交最低为46.4%,其它组合为70%~80%;杂交鱼苗经28d的人工饲养,水晶彩鲫与荷包红鲤、锦鲤的正、反杂交,同其它杂交组合比较有明显的差别,其生长速度慢,个体之间差异大,成活率低;杂交子代的体型分为3类:鲫鱼型、鲤鱼型和鲤鲫型.鳞片反光组织(虹彩细胞或鸟粪素细胞)为2类:完全型、缺失型.体色分离复杂多样,水晶彩鲫与红鲫杂交是水晶彩鲫,红鲫与锦鲤、荷包红鲤杂交是青灰色鲤鲫杂种,水晶彩鲫与锦鲤、荷包红鲤杂交都会出现水晶彩色和青灰色鲤鲫杂种.
x射线显微分析法及其在生物学医学中的应用

生物化学与生物物理进展 , 1981,
Abstract:
透明金鱼的命名和分类地位探讨

上海海洋大学学报 , 2009,
Abstract: 通过查阅大量金鱼(carassiusauratus)的研究资料和图谱,以及对透明金鱼(水晶彩鲫)和不透明金鱼(红鲫鱼)的体色遗传学研究,探讨了透明金鱼的演化、命名,透明金鱼和不透明金鱼的表现型和遗传学特点.结果发现不透明金鱼的种类,在透明金鱼中多数都会存在,而多数研究者在命名中却没有将透明和不透明金鱼区分开来,造成同名鱼既可能是鸟粪素完全型,也可能是鸟粪素缺失型.但通过对透明金鱼(水晶彩鲫)和不透明金鱼(红鲫鱼)的大量遗传学研究证明,鸟粪素完全型和缺失型金鱼在表现型和遗传特性上已发生本质的变化.因此,建议依照当前<中国金鱼名录>的分类方法,首先应从体表鸟粪素的表现型将金鱼分成2大类,鸟粪素完全(不透明金鱼)为普通金鱼,鸟粪素缺失(透明金鱼)为水晶金鱼.
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