一种综合孔径辐射计贝叶斯反演法

将贝叶斯反演理论应用于综合孔径辐射计图像反演,其基本思想是将亮温分布和可见度视为随机变量,将图像反演转换为贝叶斯推断问题.基于这一思想,分析了亮温分布的先验信息和可见度的统计特性.鉴于热辐射信号具有高斯特性,建立了亮温分布的高斯先验模型,并采用期望最大算法估计该先验模型的未知参数.可见度采用多元高斯随机变量表示,并考虑了可见度的互相关性.贝叶斯反演法能够充分利用可见度和先验信息的统计特性.仿真和实验结果表明:贝叶斯反演法能有效提高综合孔径辐射计的成像性能.     

改进的G矩阵模型法在全极化综合孔径辐射计中的应用

反演成像是综合孔径微波辐射计的一项关键内容,但反演过程是欠定的,不能提供一个确定解. 针对综合孔径辐射计中常用反演算法: G 矩阵模型法存在较大反演误差的问题,提出了一种改进的 G 矩阵模型法应用于FPIR系统中. 仿真结果表明,与传统的 G 矩阵模型法相比,改进的 G 矩阵模型法能有效地降低FPIR系统图像反演误差,以获取高精确度的观测场景的亮温分布满足FPIR系统探测海面风场、土壤湿度等应用需求.      

毫米波综合孔径辐射计的压缩感知成像方法研究

毫米波综合孔径成像辐射计(Synthetic Aperture Imaging Radiometer,SAIR)是一种适用于近场成像的高分辨率、高灵敏度传感器,但因其接收机数量大、系统复杂度高,限制了SAIR在实际场景中的应用.用少量阵元天线获取的稀疏可见度函数进行高精度成像反演是目前SAIR成像研究的热点之一.为从少量的可见度采样点中重构出具有较高精度的毫米波图像,借鉴压缩感知(Compressed Sensing,CS)的稀疏重构思想,提出一种基于二维SAIR成像模型的CS-L0成像反演算法.该算法借助SL0算法思想对二维综合孔径反演模型进行快速的l_0范数求解,可从少量可见度采样点中快速精确地重构出目标场景的亮温图像.实验仿真表明,与结合传统成像模型的一般CS反演法相比,提出的CS-L0反演法具有更高的成像精度和反演速度,能够对稀疏采样的SAIR进行快速准确的成像反演.     

毫米波综合孔径辐射图像平均噪声功率特性

针对强点源目标探测时灵敏度近似解析值与实际值偏差较大,不利于成像探测系统的性能表征问题,从毫米波综合孔径辐射图像全局入手,应用矩阵理论对图像平均噪声功率进行研究.建立了图像平均噪声功率与系统参数之间的关系,在此基础上提出均方灵敏度的概念.仿真结果表明:均方灵敏度受观测场景亮温分布的影响小,仅依赖于系统参数,更适合表征毫米波综合孔径成像探测系统性能.     

一维镜像综合孔径辐射成像方法及空间分辨率

针对传统大型综合孔径辐射计系统复杂度较高的问题,提出了一维镜像综合孔径辐射成像方法,建立了该方法的系统模型,在此基础上阐述了该方法的成像原理,利用多次联合测量解决了一维镜像综合孔径中的基线缺失以及方程组欠定性问题,推导了一维镜像综合孔径的阵列因子并给出了空间分辨率的解析表达式,通过仿真证实了该成像方法的可行性以及在分辨率方面的优越性.     

全极化综合孔径微波辐射计全极化亮温的重构

为了获取全极化信息和降低重构误差,提出了一种改进的全极化重构算法应用于全极化综合孔径微波辐射计,并分析了交叉极化对全极化亮温各分量的影响程度.仿真结果表明,与传统算法相比,改进的全极化重构算法能够有效降低图像重构误差,获取高精确度的全极化亮温数据以满足测量土壤湿度、海表面盐度、海表面风矢量等应用需求.      

干涉法测量气体温度场的深入研究

研究了光学干涉方法测量气体的温度分布,组建激光干涉测量系统,通过实验得到有温度扰动的气体流场的干涉条纹,用CCD采集干涉条纹图,并对其进行傅立叶变换、相位提取和数值计算等分析处理,得出气体的温度场分布.光学干涉法可以实现高效、高精度、全场温度分布的测量,适用于工业应用中的温度测试.     

微波辐射计热定标源的研究与计算

描述了微波辐射计热定标源在本实验室的最新研究结果,给出了一种实验热定标源的结构和工作原理,并利用密集分布的散射粒子矢量辐射传输（DVRT）模型推导得出了一种可以计及隔离层多次散射效应影响的亮温计算迭代公式。数值计算证明该亮温计算公式是正确的,可以作为辐射计热定标源的一种更具普遍性的计算方法。     

基于法布里-珀罗干涉的全光纤振动检测仪

在传统的振动测量中,激光监测装置只能测量电机的单个参数.为实现对轴中心高为56 mm及以上电机的机械振动测量,建立了双通道独立测量系统.该系统可用于同时测量电机转轴的速度以及转轴产生的振动.该实验基于法布里-珀罗干涉、散斑干涉原理得到含有振动信号和速度信号的混合信号,将合成信号分解后,运用希尔伯特变换解调振动信号以及自...     

基于DSP技术及互相关算法的光纤液滴传感器

光纤液滴分析技术是通过反映被测液体的液滴生长过程的光纤液滴指纹图,测量被测液体的物理、化学特性.互相关原理被用来对不同液体的光纤液滴指纹图进行对比分析,分析液体性质或判决2种液体的异同,DSP技术的使用提高了互相关运算的速度.基于DSP技术和互相关原理制作了实验室样机,并进行了样品测试.分别利用互相关函数和互相关系数测试了不同浓度的酒精溶液,测试结果显示,互相关函数峰值可以作为一种测量液体浓度的方法,酒精溶液的测量精度达到3.4%,而互相关系数法可以甄别不同浓度的酒精溶液,最小系数在60%以下.     

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