基于北向陀螺零偏自观测的捷联惯性导航系统双位置初始对准方法

传统捷联惯性导航系统单位置初始对准系统不完全可观测,不可观测的东向陀螺零偏造成航向估计的主要误差。双位置初始对准可以改善系统的可观测性,但一般需要精确的转位机构,不便于工程应用。该文提出一种基于北向陀螺零偏自观测的双位置初始对准方法,只需陀螺载体在近似水平的任意两个位置停留片刻,从第1位置提取北向陀螺零偏信息传递给第2位置作为观测量,即可提高东向陀螺零偏的可观测度并提高航向对准精度。为了寻找最优转角,提出一种全面可观测度分析方法,将可观测度细分为表征不同条件下同一状态可观测程度的相对可观测度和表征状态收敛速度的可观测阶两部分,利用相对可观测度分析得出最佳转角为±90°,并进行了仿真实验验证。实测实验结果表明:相比于单位置对准,双位置对准将航向误差由0.268°降低到0.041°,并可估计出水平陀螺零偏。     

基于改进灰色模型的MEMS陀螺仪零偏温度补偿

微机电系统(micro-electro mechanical system,MEMS)陀螺仪的零点漂移是影响陀螺仪测量精度的主要因素.针对MEMS陀螺仪零点漂移随温度变化的非线性问题,以MEMS惯性传感器为试验对象,采用小波变换对MEMS陀螺静态实验零偏数据进行滤波,结合改进灰色预测模型估计零偏随温度变化趋势,获得基于小波变换和改进灰色预测的温度补偿模型.与常规补偿模型算法比较表明,基于小波变换和改进灰色预测的温度补偿模型均方根误差和平均绝对误差更小,MEMS陀螺仪零点漂移的均方根误差和平均绝对误差分别减少到0.025 0和0.018 0,验证了该补偿模型的可行性,对提高陀螺测量精度具有较好的理论意义和工程应用价值.     

硅微陀螺仪零偏温度性能补控方法设计

首先从理论上推导了硅微陀螺仪谐振频率、品质因数、敏感信号输出及机械热噪声与温度之间的关系,进而说明了温度对陀螺仪零偏输出影响是各非线性因素综合作用的结果.然后,通过部分温度特性试验获得了硅微陀螺仪的模态谐振频率和品质因数随温度变化关系曲线.最后,根据实测零偏试验数据给出了分段多项式温度补偿方法,并进一步结合恒温控制方法...     

线振动条件下激光陀螺捷联惯导附加漂移补偿技术

针对振动条件下惯性器件会产生较大漂移的问题,从导航误差方程出发,以速度和位置误差作为观测量,设计了双位置卡尔曼滤波初始对准测漂方法。利用这种方法对振动条件下系统中激光陀螺的零漂和加速度计的零位的变化进行了估计;同时在导航解算过程中对惯性器件的振动附加漂移进行补偿。振动条件下对准测漂实验表明:利用双位置卡尔曼滤波方法可以很好的估计出惯性器件的振动附加漂移。振动漂移误差补偿实验表明:在导航结算过程中对惯性器件的振动漂移进行有效补偿后导航精度明显提高。     

光纤陀螺零偏温度补偿的实验研究

为光纤陀螺因温度效应而产生的零偏提供一种补偿方法,针对自行研制的光纤陀螺仪的零值漂移,根据实验数据,建立一种温度补偿模型,采用最小二乘法拟合计算出所需的修正系数对其预测补偿.补偿结果表明:光纤陀螺经模型补偿后零偏基本可以减少一个数量级,并进一步提高了零偏稳定性,补偿效果明显.     

旋转捷联惯导系统的可观测性分析

推导了静基座条件下仅利用速度误差作为观测量的惯导系统的可观测组合状态.比较分析认为,仅利用速度误差作为观测量和利用速度误差、位置误差作为观测量对惯导姿态误差和元件等效零偏的估计是等效的.利用将系统近似为分段线性定常系统的方法对旋转惯导系统的可观测性进行研究,结果表明,连续旋转提高了系统状态的可观测性,等效东向和北向加速度计零偏成为可观测量;在对准过程中对其进行补偿,系统的对准精度和速度明显提高.     

基于非线性滤波的捷联惯导系统罗经法对准改进算法

为提高捷联惯导系统初始对准的快速性和精确性,根据传统的平台惯导系统罗经法对准原理,提出包括水平对准和方位对准的捷联式罗经对准算法.给出了导航坐标系下加速度和角速率的修正值,经过姿态矩阵的转换对载体坐标系下的惯性测量组件输出值进行修正补偿.对不同初始姿态角误差和不同初始航向角的仿真表明,初始航向角的改变对系统影响较大,特别在大方位失准角情况下.采用UKF算法对非线性模型滤波的仿真结果显示,最大航向角误差从15′降至6′,证明将罗经法和UKF滤波方法相结合进行捷联系统初始对准是可行有效的.     

基于联邦网络的传递对准滤波补偿算法

针对空中环境各种干扰因素对空空导弹传递对准(TA)滤波的影响,提出一种基于联邦网络的补偿算法.将干扰误差考虑为量测输入纳入滤波系统,改进标准Kalman滤波结构.将补偿神经网络设计成联邦结构,两个子系统分别用于训练量测输入估计误差、输出层权值误差和隐层权值误差.推导了联邦网络的训练算法并对算法进行了稳定性证明,保证了网络在结构上计算量小,系统反馈能力强,能够对干扰误差进行有效在线预测,辅助改进Kalman滤波器对失准角进行精确估计.仿真比较实验验证了该算法能够在不需任何先验信息的条件下,及时适应对准环境,预测校正干扰误差,滤波收敛快、精度高,适合空空导弹在具体设备和环境条件下的快速精确传递对准.     

改善MEMS陀螺误差温度稳定性的驱动力补偿方法

由于微机电系统(MEMS)陀螺通常采用微加工工艺生产制造,因此总是受微加工过程带来的的各种精度缺陷影响。对于MEMS陀螺,其零位输出误差因受环境因素影响而无法保持稳定,随时间表现出漂移特性,这种特性严重限制了MEMS陀螺在更高精度应用中的可用性。该文研究了一种改善MEMS陀螺零位误差温度稳定性的方法。通过分析陀螺运动特性及主要误差源,阐明陀螺驱动力对检测方向的耦合作用是零偏误差同相分量产生并随温度漂移的主要原因之一。为抑制陀螺驱动力耦合作用,提出对陀螺检测轴施加补偿静电力的方法。温度试验结果表明:施加补偿作用后,陀螺零偏误差同相分量的温度稳定性在12～60℃范围内提高了3倍以上。     

基于滤波估计的传递对准观测值延时抑制方法

传递对准过程中,由于主惯导的解算和传输延迟,子惯导解算信息与进行匹配的基准信息不能完全同步,有些情况下时间延迟较大。分析了时间延迟对速度加姿态角匹配传递对准的影响,并提出了一种时间延迟估计与补偿方法。建立了主惯导时间延时模型,推导了包含时间延时的传递对准观测方程。仿真结果表明,未补偿主惯导信息时间延迟,传递对准失准角估计误差达到40′左右,补偿后,传递对准失准角估计误差在6′以内。该方法可以有效降低由于主惯导信息延时而导致的估计误差发散现象,提高了传递对准精度。     

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.     

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