采用多载波相位测距的Wi-Fi精密定位方法

针对当前室内无线局域网Wi-Fi定位方法误差大、需要额外辅助设备的问题,提出了一种基于多载波相位测距的Wi-Fi精密定位方法。在测距环节,通过中国剩余定理求解多载波相位同余式组实现了距离重构,并给出了一种采用同差处理以降低算法噪声敏感性的方法;在定位环节,基于最小测距误差平方和准则,将带有误差的多边测距定位问题转化为受约束的二次最优规划问题,实现了分米级的Wi-Fi定位。实验与仿真结果均表明,所提方法的测距精度可达mm级,定位精度在dm级,较主流MUSIC Wi-Fi定位方法3~5m的定位精度提升了4倍以上。     

渐进提高精度的载波相位测距技术

提出了一种静止、可视两目标之间基于载波相位高精度测距技术:第一步,借助GPS、伪随机码相位自主测距或超宽带等辅助测距手段得到一个距离粗测值和测量精度;第二步,基于已有距离粗测值和测量精度选择载波频率对,消除基于载波相位测距时引入的整周模糊度问题,然后基于载波相位双-单边测距技术,并借助伪码相位消除两目标上面载波相位观测时间差,得到一个精度更高的距离测量值;基于新得到的距离测量值和测量精度,重复第二步过程,渐进提高测距精度直到满足需要的精度为止。理论分析和现有工程技术实现表明,最终测距精度可达微米级。     

基于载波相位的室内伪卫星定位系统设计方案

提出了一种基于载波相位的室内伪卫星定位系统设计方案。通过伪卫星上加装双天线、设定合理的天线基线长度,同时采用频分和码分多址技术,实现了基于载波相位测量距离差的双曲面定位体制,较好地解决了传统伪卫星定位中存在的时钟同步、多路径条件下测距精度提升和远近效应等技术难点。仿真结果表明,有利于提高室内伪卫星的定位精度。     

基于单天线相位的UHF RFID室内定位算法研究

基于单天线相位的UHF RFID,采用双标签的定位方法,对室内定位算法进行了研究,结果表明:待定位目标边长距离在超过高频载波信号波长的情况下,有2个间距为1/2载波波长的无源标签附着于特定目标上。仿真表明:在三条路径、两条路径情况下,两步测距可估计平均定位误差;两步测距(副载波)方法也可估计平均定位误差;但两步测距(副载波)方法基于双标签定位中,无法确保阅读器与2个标签间距离大小关系。在三条路径、两条路径情况下,两步测距(副载波)方法误判率分别为17.45%、17.82%,两步测距(载波)方法误判率均为0,故两步测距(载波)方法可将定位误差降低,确保物品登记准确性。     

测量范围可调的高精度激光相位测距系统研究

提出了距离范111可调的高精度激光相位测距秉统的研究方法。系统采用脉冲测距方法预测距离范围,定位目标后,运用多个辅助频率激光相位洲距技术进行精确测距。秉统内外接收电路独立分开,并采用了自动数字测相技术,达到了高精度,洲量范围可调的实际要求。     

一种基于运动学原理的单星对星无源测距定位方法

在对卫星的无源定位跟踪研究中,目标距离的获得是关键问题。测角类的定位方法不能即时测距,且存在收敛慢、精度低的不足。根据运动学原理和卫星运动动力学方程,推导无源测距方程并给出解法,从而提出一种无源测距方法。在此基础上,结合测距分解观测模型,给出基于运动学原理的单星对星无源测距定位方法。仿真实例验证了测距方法及基于测距的定位跟踪方法的正确性和有效性。与已有的基于几何定位原理的测角类定位方法相比,该方法具有更高的定位精度和更快的收敛速度,可实现快速定位。     

基于调频测相的激光引信测距方法研究

为提高激光引信测距精度和实时性并降低系统实现难度,提出了一种基于调频测相的激光测距方法,该方法采用正弦调频+相位测距的方式实现测距. 重点分析了调频测相激光测距原理,指出了影响测距精度的主要因素. 提出采用基于Hilbert变换的相位差测量方法可提高测相精度,并进行了相关的仿真验证. 仿真结果表明,在信噪比为14 dB的情况下测距精度优于0.1 m,且有较强的测距实时性,此方法可用于激光近炸引信.     

基于最小二乘法的相位式激光测距仪

针对传统便携式激光相位测距仪测量精度较低和实时性不够的缺点,设计了一款高精度快速相位式激光测距仪.首先由ARM芯片对回波信号采样并使用最小二乘法求解信号相位;然后根据粗测尺求得待测目标的模糊距离,计算不同频率信号的周期差,构建超定方程组;最后应用最小二乘法求解出待测距离.对2台测距样机和1台K60测距仪在精度为0.18mm的国家标准基线上进行测距比较试验,结果表明:测距仪的平均测量误差不大于0.95mm,标准不确定度不大于0.50mm,平均测距时间不大于1.55s,测距精度和测距速度比K60测距仪都有了较大提升,满足市场上测距仪误差小于2mm和测距时间小于3s的应用要求.     

基于双探测器的手持式激光测距仪系统设计与实现

针对传统激光测距仪测距精度低、成本高以及速度慢等问题,设计一种基于双探测器的手持式激光测距仪。该测距仪使用分束镜实现光路内校准,设计检相电路将信号相位转变为带有相位信息的直流电平,并使用CORDIC数字计算方法求解相位,最后应用基于超定方程组的测距解模糊算法求解待测距离,对3台双探测器测距仪和2台K60测距仪以精度0.18 mm进行测距比较试验。研究结果表明:与传统测距仪相比,光路内校准可以消除电路附加相移,检相算法简单快速,解模糊避免对最优距离的搜索,因此提高了测距精度和测距速度。在0~60 m的测程内,3台双探测器测距仪的平均测距时间小于1.8 s,平均测量误差小于2 mm,测量标准差小于1 mm。与K60系列测距仪相比,双探测器测距仪测距精度和测距速度都有较大提升,验证了该设计方案的可靠性。     

基于数据共轭映射的载波间无扰消除方法

结合实际应用中收发信电台的本振往往存在相位噪声的问题,分析了相位噪声对子载波信号的影响,并针对相位噪声引起的子载波间干扰,给出并分析了基于数据共轭映射的干扰消除方法,对该方法的BER性能和PAPR性能进行了仿真,实验结果表明,基于数据共轭映射的子载波间干扰消除方法具有良好的系统性能。     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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