解析未来移动通信系统中的智能天线技术

如何消除同信道干扰（CCI）、多址干扰（MAI）与多径衰落的影响是提高无线移动通信系统性能的主要因素。智能天线利用数字信号处理技术,产生空间定向波束,使天线主波束对准用户信号到达方向,旁瓣或零陷对准干扰信号到达方向,可以达到高效利用移动用户信号并抑制干扰信号的目的。     

基于数据预处理的改进GS正交化波束形成

针对常规Gram-Schmidt（GS）正交化算法在训练快拍中混有期望信号时,自适应波束会出现期望信号相消的问题,提出了基于数据预处理的改进GS正交化波束形成算法. 该算法构造阻塞矩阵进行数据预处理剔除期望信号,估计对应的协方差矩阵,并对其进行GS正交化重构干扰子空间,将静态加权矢量向干扰子空间作正交投影得到自适应权矢量. 同时,为准确估计干扰子空间,对协方差矩阵的正交化自适应门限进行了修正. 仿真结果表明,所提算法的输出信干噪比（SINR）比其它GS正交化算法有2 dB以上的性能改善.      

一种低副瓣宽零点的自适应波束形成算法

自适应波束形成算法能自动地将波束的主瓣对准期望用户信号的来波方向,零陷对准干扰信号的来波方向;但是常规的自适应算法形成的干扰零限比较尖锐,副瓣容易产生畸变,在干扰、天线平台快速移动的情况下,其性能将会严重下降.基于对权值的范数约束和对零点的最小二乘线性约束优化,提出了一种降低副瓣电平并且加宽零点的自适应波束形成算法.理论分析和计算机仿真结果证明了新算法的有效性.     

基于复合权的多用户STC联合波束形成技术

为克服基于特征值分解（EVD）的空时编码（STC）联合波束形成技术在多用户干扰系统中性能的恶化，该文提出了1种卷积复合权结构，将发射波束等效为2个分别具有不同功能的子波束的相乘叠加，实现空时编码在空间分集上的技术优势与波束形成在加强期望信号和干扰抑制特性的最优组合，在获得空时编码空间分集增益与波束形成的阵列增益同时，实现对其它用户干扰的零陷抑制。仿真结果表明，基于复合权的联合空时编码与波束形成方案与传统基于特征值分解的联合方案相比，系统可靠性和系统容量都有显著的提高。     

一种基于特征子空间扩展的自适应波束保形方法

基于特征空间(ESB)自适应波束形成算法，提出了一种扩展信号子空间的自适应波束保形方法(SESB)，该方法通过扩展信号子空间、舍弃噪声子空间，克服了当干扰信号和期望信号同时存在时，期望信号大范围的变化造成波束畸变这一缺陷，计算机仿真和分析证明该方法运算量小，具有良好的波束保形能力和稳健性。     

一种低副瓣宽零点的自适应波束形成算法

自适应波束形成算法能自动地将波束的主瓣对准期望用户信号的来波方向，零陷对准干扰信号的来波方向；但是常规的自适应算法形成的干扰零限比较尖锐，副瓣容易产生畸变，在干扰、天线平台快速移动的情况下，其性能将会严重下降。本文基于对权值的范数约束和对零点的最小二乘线性约束优化，提出了一种降低副瓣电平并且加宽零点的自适应波束形成算法。理论分析和计算机仿真结果证明了新算法的有效性     

面向语音增强的聚焦自适应波束形成方法

针对语音信号相对带宽大、麦克风存在误差以及现有自适应波束形成方法宽带干扰抑制能力不足的问题,提出一种面向语音增强的聚焦自适应波束形成方法。首先将Capon空间谱处理为接收信号的概率密度函数,并对不同频带设计了基于阵列观测数据的聚焦矩阵,从而根据干扰功率自动调整频率聚焦程度;然后,计算聚焦后的样本协方差矩阵和各子带频段内的干扰加噪声协方差矩阵,并利用聚焦矩阵重构出宽带数据的干扰加噪声协方差矩阵;最终,通过重构出参考频率下的期望信号协方差矩阵,修正期望信号方向的导向矢量并得到自适应波束形成器的加权向量。数值仿真结果表明：所提方法能够有效地对期望信号进行接收的同时充分抑制宽带干扰;所提方法在强干扰处的聚焦误差仅为现有方法的约1%;在信噪比为15 dB且入射角误差为3°的情况下,所提方法的输出信噪比较现有方法提高约12 dB。     

基于软件无线电的智能天线

20世纪90年代以来,随着通信技术的发展,智能天线成为一个新的研究热点。经研究发现,智能天线可将无线电的信号导向具体的方向,产生空间定向波束,使天线主波束对准用户信号到达方向DOA,旁瓣或零陷对准干扰信号的方向,达到充分高效利用移动用户信号并删除或抑制干扰信号的目的。利用各个移动用户间信号空间特征的差异,通过阵列天线技术在同一信道上接受和发射多个移动用户信号而不发生相互干扰,使无线电频谱的利用和信号的传输更有效。智能天线应用非常广泛,它在提高通信质     

一种基于特征矢量波束形成算法

针对已有算法不能很有效地处理相关干扰,引起期望信号相消的现象,提出一种基于特征矢量的新的智能天线波束赋形方法,并用Matlab对其进行了仿真,仿真结果表明：这种算法在相干环境下,能有效的抑制相关干扰,在期望方向形成最大波束。     

基于子空间技术的常规多波束形成抗干扰算法

卫星导航系统(GPS)的很多抗干扰技术是以卫星信号来向估计为基础的,当估计卫星信号来向有困难时,这些算法将失效.提出了一种基于子空间投影的常规多波束抗干扰算法.该方法先进行子空间投影抑制干扰,然后在固定方向上采用常规波束形成方法(CBF)形成多个主波束,最后对每个波束得到的无干扰数据进行捕获及定位解算等.该方法的特点是...     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that