衰落信道中基于CMA的自适应多用户检测算法

提出了一种能在多径下使用的基于CMA的多用户检测结构,实验仿真证明,在时延远小于符号时间的情况下,这种多用户检测算法能很好抵消多址干扰和克服多径衰落,算法的收敛性能稍弱于子空间自适应多用户检测,而稳态性能稍强于子空间多用户检测,算法的复杂度远低于子空间多用户检测算法。     

基于子空间跟踪的盲空时多用户检测

针对天线阵同步CDMA系统,运用子空间方法,提出多径条件下空时盲多用户检测方法.用FSYAST子空间跟踪方法来自适应估计信号子空间,同步多径天线阵列系统的信道参数采用Kalman算法自适应估计.仿真结果表明,提出的盲空时多用户检测器性能优于其它子空间多用户检测器.     

异步DS-CDMA系统盲自适应多用户检测

目的提出适用于多径衰落信道中的异步DS-CDMA盲自适应多用户检测算法。方法通过研究多径信号码空间和数据矢量空间,采用噪声子空间技术进行异步DS-CDMA系统期望信号矢量估计,同时利用了多径传播和接收机同步失调的特性。结果使用一种修改的ULV更新算法进行噪声子空间跟踪。结论仿真结果验证了本文算法的有效性。     

多径MIMO CDMA系统中改进的盲空时多用户检测算法

针对多径衰落信道下发射分集采用Alamouti空时分组码的MIMO CDMA系统,提出了一种改进的基于子空间的盲MMSE空时多用户检测算法.结合目标用户特征波形先验知识和多径信道信息对信号子空间进行预处理,然后使用正交性能和稳态性能较好的NOOja算法跟踪信号子空间,并在跟踪初期对信号特征值矩阵进行处理,去除迭代带来的噪声.仿真结果表明这种算法能有效地抑制多径干扰和多址干扰,尤其在低信噪比、远近效应明显的恶劣环境下,有稳定良好的性能表现.     

多径信道下基于最小平均峰度准则的盲多用户检测算法

基于最小平均峰度(LMK)准则,提出了一种适用于同步直扩码分多址(DS/CDMA)系统多径慢衰落信道中的盲自适应多用户检测算法.这种算法基于高阶统计量特性,算法复杂度相对较低.仿真结果表明,该算法的稳态性能与子空间自适应多用户检测算法相当,是一种较好的多用户检测算法,有一定的实际应用价值.     

多么CDMA系统的子空间线性算法

基于子空间分析的算法是线性多用户检测算法中一个较新的研究方向,目前许多文献中主要是对针对单路径信道进行研究。本文提出了ＣＤＭＡ系统的多径信道模型的通用矩阵表示形式,对文献「６」中提出的算法进行了改进,提出了多径干扰下基于子空间概念的线性算法,仿真显示,该算法比原来的算法具有更好的抗多径干扰能力。     

基于信号子空间的盲自适应多用户检测

多用户检测技术是DS—CDMA中解决多址干扰问题的一种重要技术。针对基于PASTd多用户检测方法在子空间追踪收敛速度慢和收敛的不稳定问题，提出一种快速子空间追踪的盲自适应多用户检测改进算法。该算法通过空间分解得到信号子空间，并利用信号子空间的特征值和特征向量得到解相关多用户检测器；最后，应用归一化正交Oja快速自适应地追踪信号子空间。仿真结果表明，相对PASTd多用户检测方法，降低计算复杂度，加快算法的收敛速度，系统稳定性好，拟制多址干扰具有良好的性能，达到很好的多用户检测效果。     

基于子空间跟踪的线性共轭半盲多用户检测

考虑实际的MC-CDMA上行链路系统,在深入研究基于子空间的MMSE半盲多用户检测算法的基础上,针对原算法引入子空间误差导致检测性能下降的问题,提出MC-CDMA系统下一种基于子空间跟踪的线性共轭MMSE半盲多用户检测算法.将子空间方法和线性共轭的思想相结合,应用新定义的信号子空间设计了基于子空间方法的线性共轭MMSE检测器,采用OPAST子空间算法实现了信号子空间的自适应跟踪.仿真结果表明,与以往的基于子空间的MMSE半盲多用户检测相比,此算法有效地提高了信干噪比,降低了系统的误比特率.     

基于FSYAST子空间算法的盲自适应多用户检测

为解决传统算法因引入特征值估计误差而导致检测性能下降的问题,在分析基于信号子空间跟踪的最小均方误差(MMSE)多用户检测器(MUD)的基础上,提出了一种改进的信号子空间盲线性MMSE多用户检测器,并应用FSYAST子空间跟踪算法进行信号子空间跟踪.仿真结果表明,提出的盲自适应多用户检测器性能接近于奇异值分解(SVD)子空间多用户检测器性能.     

一种改进的基于MMSE准则的空时多用户检测算法

该文对最小均方误差(MMSE)算法进行了研究,为了能更有效地减轻延时扩展及多径衰落,改进CDMA移动通信系统的容最和质量,以及进一步降低误码率.推导出了一种在多径CDMA信道下改进的空时MMSE多用户检测算法,该算法利用最陡下降算法求解空时多用户检测的最优权因子,并且提出了相应的检测器的结构.该算法改进了传统的MMSE多用户榆测算法,具有稳定的收敛特性和良好的检测性能,并给出了相应的计算机仿真结果.     

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