一种非匀速连续旋转寻北的新方法

连续旋转寻北方法是一种新的动态寻北方法。但是要求转台连续旋转过程中转速为匀速旋转,这对电机控制和转台机械加工提出了很高的要求。实际实现起来有一定的困难。研究了一种连续旋转寻北在非匀速旋转情况下的新的寻北方法。在非匀速旋转过程中进行采样、数据处理。仿真结果表明,该方法在转台非匀速旋转的情况下仍能达到很好的寻北精度,与匀速旋转时传统动态寻北方法精度相当,可大大降低寻北仪的加工成本。     

对光纤陀螺寻北仪二位置寻北方案的改进

在传统二位置寻北方案基础上,针对光纤陀螺寻北仪提出了一种新方案。它将传统的水平面内旋转寻北改为竖直面内翻转寻北,所以不再需要像以往寻北仪那样在寻北时间和寻北精度之间进行折衷处理,可以在减少寻北时间的同时,提高寻北精度,并使寻北仪对光纤陀螺仪（FOG）和转台性能的依赖程度大幅降低。     

基于B-小波提高寻北仪抗基座扰动的能力

为消除静基座寻北时外部基座扰动对寻北仪精度的影响，提出采用波形反对称的三阶B-小波对寻北仪原始输出信号进行滤波处理，通过对多尺度下小波变换模极大值的分析，可以确定低频基座扰动在时域上的作用点，从而消除受污染数据对寻北精度的影响，利用实测数据进行的仿真表明，该方法能有效地提高寻北仪抗基座扰动的能力。     

采用数据处理方法提高车载捷联式寻北仪的精度

本文采用数据处理方法来提高车载捷联式寻北仪在受到外界干扰时的寻北精度.详细分析了捷联式寻北仪的寻北原理和外界干扰产生寻北误差的原因,提出了低通滤波方法和两种类型的统计分段方法.试验数据和仿真结果表明,所提出的方法对于寻北仪抑制某些外界干扰从而提高寻北精度是非常实用和有效的.     

光纤陀螺寻北滤波方案研究

提高寻北精度和缩短寻北时间是光纤陀螺进行方位寻北需要解决的主要技术问题。本文通过采用粒子滤波算法对光纤陀螺的噪声和零位漂移进行滤除和补偿,并建立多位置寻北模型。根据陀螺的实测值,用计算机仿真的方式解算出真北方向。分析比较结果显示,粒子滤波算法可以在保证寻北精度条件下实现快速寻北。证明了该方案的可行性和实用性。     

陀螺寻北仪中的控制回路设计

陀螺寻北仪是一种测出真北的仪器,在军事上及工业上有着广泛应用.好的陀螺寻北仪对寻北的时间、精度都有很高的要求,其关键在陀螺本身的精度以及力反馈控制回路和转位机构回路的控制器设计.应用Matlab软件仿真并设计了数字PID控制器,数字化伺服系统使得系统小型化,直接修改软件使得现场调试很方便,DSP的应用可以对信号做算法处理,这些保证了寻北时间短,精度高.     

旋转调制式寻北仪滤波技术研究

研究用机械旋转和数字滤波的方法提高寻北仪精度.利用连续恒速旋转方法对陀螺信号进行调制,用积分方法进行解调,以抑制陀螺常值漂移、漂移趋势项和刻度因数误差对寻北精度的影响,用设计的低通滤波器对含有随机漂移和系统干扰的陀螺信号进行滤波.实验结果表明这两种措施可有效提高寻北仪方位角估计精度.     

寻北仪寻北方法研究

一、概述惯性寻北技术是惯性技术领域的重要组成部分,是现代信息化战争中确保武器系统快速、机动、精确打击的重要保障技术之一。因此,国际上众多发达国家均在发展高性能战略、战术武器的同时,也投入大量人力,物力研制开发精度更高、更快速寻北的系统。无论气浮陀螺、液浮陀螺、光纤陀螺、磁悬浮陀螺、激光陀螺寻北仪,都可以全天候可靠地工作,不受外部环境如地球磁场、地形、气候的影响;都可在没有任何外部方位信息情况下实现自主寻北功能,测出当地地理北向。     

自由陀螺式静电陀螺找北仪原理与系统测试

提出了自由陀螺式静电陀螺找北仪的原理，并给出了系统测试结果。自由陀螺式静电陀螺找北仪采用角度法寻北方案，在工作中陀螺处于自由状态，通过光电传感器观测陀螺转子的表观运动角度，经过数据处理，得出方位角。为了降低陀螺漂移逐次启动不重复性对寻北精度的影响，系统引入两位置差动测量方法。实验表明，依据提出的方案研制的静电陀螺找北仪寻北时间小于３０ｍｉｎ，寻北精度可达１５″     

连续旋转式寻北仪的寻北算法及信号处理

研究一种连续旋转式寻北仪.推导了该寻北仪在无姿态下的寻北解算公式.为了提高系统的寻北精度,对其干扰源进行了分析,采集了陀螺和加速度计的信号,根据其信号特点提出了基于快速傅里叶变换(FFT)的滤波方法,应用该方法对陀螺单次寻北数据进行了滤波,并与原始数据作了比较.在此基础上提出了对多次寻北结果采用多周期平均的数据处理方法.实验结果表明,系统在精确调平状态下寻北340 s即可达到0.008 3°的寻北精度.     

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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