基于决策融合的GNSS欺骗干扰检测性能分析

欺骗干扰是一种旨在迫使GNSS接收机得到错误导航信息的蓄意攻击。卫星导航接收机需要及时且准确检测出现的欺骗干扰信号。本文借鉴认知无线电中协作频谱感知的思想,提出了一种基于决策融合的卫星导航欺骗干扰检测算法。首先采用能量检测算法,分析并推导了单个检测器在瑞利衰落信道下的卫星导航欺骗干扰检测性能,然后应用K/N准则的决策融合方法以进一步改善欺骗干扰的检测性能。仿真结果表明:当SINR=-10 d B时,检测概率比单次检测概率平均提高了16.60%。     

转发干扰下匹配滤波P码捕获性能分析

为了有效抑制转发式干扰,在采用匹配滤波捕获方法的基础上,提出了基于延迟-等待捕获策略的抗转发干扰P码捕获方法,给出了具体的实现过程,对转发式干扰情况下该方案的有效性和强转发干扰下的局限性进行了理论分析,对有转发式干扰信号场景下匹配滤波P码捕获方案进行了仿真.仿真结果验证了理论分析结果,为军用抗干扰卫星导航接收机的设计提供了参考.     

基于Wigner-Hough变换的卫星导航接收机扫频干扰信号检测

抗干扰技术对全球导航卫星系统(global navigation satellite system,GNSS)非常重要,文章研究了导航接收机中扫频干扰检测。传统的时频分析方法如短时傅里叶变换(short-time Fourier transform,STFT)、谱图法,存在时频分辨率折衷问题。Wigner-Ville分布(Wigner-Ville distribution,WVD)具有交叉项。为了解决这些问题,文章提出了一种新型的基于Wigner-Hough变换(Wigner-Hough tranform,WHT)的时频分析算法。在不同干噪比(jammer-to-noise ratio,JNR)情况下,比较谱图、WVD和WHT干涉检测的性能。仿真实验结果显示,在弱干扰信号情况下,WHT算法检测干扰信号的性能更好,为GNSS接收机干扰检测提供有效性和准确性保证。     

基于静态调度表的雷达抗干扰软件设计

雷达抗干扰技术是当今雷达领域的热点。本文采用独立分量分析算法,从雷达回波信号中提取目标信号,抑制干扰信号。在系统实现上,利用静态调度表机制,实现目标检测和抗干扰的并行化计算架构设计。通过实验表明,应用这种架构分离目标信号与干扰信号取得了较好的效果。     

抗转发干扰FFT快速捕获方法研究

为了解决有效抑制转发式干扰问题,根据转发干扰信号的码相位滞后于卫星导航信号的特点,结合快速傅里叶变换(FFT)快速捕获的二维搜索策略,提出基于延迟-等待捕获策略的抗转发干扰FFT快速捕获方法.该方法根据过门限峰值的码相位信息来区分判别卫星导航信号和转发干扰信号,在不影响接收机在无转发干扰正常工作的条件下,保证了接收机在转发干扰下的捕获性能.理论分析和仿真实验验证了该方法的有效性.     

调零天线中的空域极化域联合抗干扰算法

在期望信号功率较小情况下,强同频干扰容易造成系统灵敏度下降,比如卫星导航和卫星通信。采用一个4阵元正交极化阵列,可以通过空域和极化域联合方式对干扰进行抑制。阵列参考阵元位于圆心,其余3个阵元均匀分布在圆周上。自适应滤波采用功率倒置准则下的 LMS算法,该方法调整每个正交极化阵元权系数,使得阵列在干扰极化下等效的极化匹配因子接近为0,实现干扰抑制。算法无需信号空间信息,实现简单,同时使阵列自由度达到6,从而增加抗干扰个数。计算机仿真证明了4个阵元阵列可以有效抑制最多6个干扰,而且,通过极化域处理,即使干扰信号与期望信号入射角度相同,只要极化不同,也可以抑制干扰而保持对期望信号增益。     

一种减少多径干扰的卫星信号跟踪环路设计

抗干扰技术是卫星定位导航领域中一项重要的技术,也是信号处理学科的一项重要分支。以减少卫星信号多径干扰为目的,结合多径环境下的卫星导航信号模型和卫星导航信号的跟踪捕获原理,设计出一种抗多径干扰性能较好的信号跟踪环路,该信号跟踪环路能在经典信号跟踪环路的基础上减少卫星信号的多径干扰,从而提高了整个卫星导航系统的抗干扰性能。     

工业电子控制装置常见的干扰及抑制的硬件措施

分析了工业现场使用的电子控制装置中常见的几种干扰信号的特性及在使用这些装置时应注意的抗干扰问题,并介绍了几种常用的干扰抑制措施.     

BLMS算法在GNSS天线抗干扰中的应用

首先,简要介绍了国内外卫星导航抗干扰研究现状,结合BLMS(Block Least Mean Square)算法在GNSS抗干扰方面的应用,给出了其硬件实现的方框图和信号流程图,并对实现中存在的问题进行了分析;其次给出了一种实验室条件下模拟干扰环境,进行抗干扰算法研究的方法,即用信号发生器模拟干扰源和卫星信号,使其通过由功分器和合路器搭建的模拟阵列信号单元模拟干扰环境;最后,用单频干扰和扫频宽带干扰测试算法的抗干扰性能,并用Matlab编写的基带处理程序对算法的输出进行码相关,测量输出信号信干噪比(SINR)变化,以检验其有效性.数据表明,该算法具有良好的抑制干扰能力,为GNSS抗干扰研究提供了参考.     

时频分析和Fisher聚类的转发式干扰抑制算法

针对雷达对抗中转发式欺骗干扰的抑制问题,提出了一种基于时频分析和Fisher聚类的干扰鉴别及抑制算法。通过STFT变换,分析并提取了回波与干扰信号的时频特性差异,在信号检测基础上,采用Fisher聚类法实现了干扰与回波的分离,并通过时频滤波实现干扰抑制。仿真结果表明,能有效对抗频移调制实时转发干扰,当干扰与回波处于不同时辨单元时,可直接滤除干扰信号,且对干信比不敏感;处于相同时辨单元时,可有效抑制干信比小于25 dB的干扰信号。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with