拒止环境下的塔康欺骗干扰

为解决塔康欺骗信号在接收机处捕获率不高的问题,设计了通过施加带限白噪声构建拒止环境,掩护干扰信号进入机载接收机,提高欺骗信号相对捕获概率的新干扰模式。首先分析了塔康测距解算时噪声信号对解算结果的影响,研究了该干扰模式下所需欺骗干扰功率随干扰机与飞机距离的变化情况,进而分析了欺骗信号在施加带限白噪声协助下相对捕获概率随干信比的变化。最后通过仿真验证,证明所提出的欺骗干扰模式可以实现对真实测距应答信号的有效压制,使欺骗信号成功被机载接收机捕获。     

电子干扰下GPS接收机C/A码捕获性能的研究

研究电子干扰对卫星定位系统(GPS)接收机C/A码捕获性能的影响.分析了C/A码平均捕获时间和捕获时间方差,并且进行了基于连续波、宽带及部分频带3种干扰模式的模拟分析.分析结果表明,若针对GPS接收机的干扰功率超过一定强度后,平均捕获时间和捕获时间方差指标将急剧恶化.在相同的GPS接收机中频输出信干比下,连续波干扰较宽带干扰效果更加明显.     

GPS军码信号的带限高斯噪声干扰参数选择分析

为了提高带限高斯噪声对GPS军码信号的干扰效率,以GPS接收机的码跟踪误差作为干扰效果评估指标,对其特定干信比下的干扰频偏和干扰带宽进行优化确定。在分析GPS P(Y)码和M码信号功率谱特点的基础上,根据非相干超前减滞后处理码跟踪环路工作原理,理论推导得到干扰频偏和干扰带宽与码跟踪误差的解析式。基于实际情况设置接收机码环参数,分别定量地仿真计算出不同干信比下针对P(Y)码和M码信号的高效干扰频偏和干扰带宽。以造成码环失锁所需干信比最小为主要评判准则,同时考虑干扰易实施性和频域滤波等因素的影响,通过综合比较得出:当干信比在50~60dB范围内时,针对P(Y)码信号的干扰频偏和干扰带宽分别设置为0和8.8MHz,针对正弦BOC和余弦BOC调制的M码信号的干扰频偏分别设置为9.833 MHz和10.9 MHz,干扰带宽统一设置为10 MHz。     

多路GNSS欺骗干扰信号功率控制策略

为满足多路GNSS欺骗干扰信号整体获得目标接收机高捕获性能的实际应用需求,设计了一种多路信号互相关干扰约束下的信号功率最优控制策略。分析了多路欺骗信号功率对噪声基底的影响,研究了在此情况下欺骗信号的捕获性能。以噪声基底上升和欺骗信号相对捕获概率为约束,构建了控制策略的目标函数,利用遗传算法进行寻优计算。仿真结果表明,该策略实现了多路欺骗信号的捕获性能优于真实信号,且此时噪声基底的抬升不超过10 dBW,欺骗信号功率不具有相关性。     

GPS接收机宽带噪声干扰性能分析与仿真

通过分析GPS信号模型,根据接收机的码跟踪环、载波跟踪环抖动门限确定等效载波-噪声功率密度比门限值,最后由干扰信号链路公式得出干扰源距离与干扰功率的关系并进行了仿真验证.     

GPS接收机载波同步环路的研究

GPS全球定位系统是由美国研制的,利用卫星进行导航定位的系统,已经得到了广泛的应用.GPS接收机的用途就是实现定位功能.GPS接收机对GPS信号中的载波信号进行捕获和跟踪是导航定位的基础.为此,本文对GPS接收机捕获和跟踪载波信号进行研究,采用COSTAS环来实现载波的捕获与跟踪.并在MATLAB环境下进行仿真验证,来检验捕获和跟踪GPS信号载波的能力.     

基于DOD和PTD的北斗欺骗式干扰检测技术研究

为在信号跟踪阶段检测到北斗信号的欺骗式干扰,通过对跟踪阶段北斗导航信号系统模型的分析,提出基于信号功率异常检测(PTD)和基于多普勒频移检测(DOD)的欺骗干扰检测算法,来实现北斗接收机在信号跟踪阶段的欺骗干扰检测,以北斗软件接收机为实验平台,通过仿真验证了所提算法的有效性。     

欺骗干扰对GNSS矢量跟踪环路的影响

矢量跟踪技术是卫星导航领域的关键技术之一。随着欺骗干扰对卫星导航安全的威胁日益严峻,研究欺骗干扰对矢量接收机的影响对于提高矢量跟踪技术抗欺骗干扰能力有重要意义。该文研究了欺骗干扰对3种典型矢量跟踪环路的影响,推导了欺骗干扰引起的跟踪误差均值,建立了环路失锁条件的表达式,并利用信号源模拟器和软件接收机对分析结果进行了验证。研究结果表明,欺骗干扰能够导致非零均值的信号跟踪误差,降低环路的跟踪性能,甚至引起环路失锁。矢量接收机可以根据该特性进行反欺骗。     

超宽带系统中盲自适应降秩接收机

针对超宽带系统中的多址干扰和码间干扰问题,提出了一种低复杂度的盲自适应接收机,该接收机首先采用多级维纳滤波算法抑制多址干扰并提取期望信号各多径分量;再进一步采用紧缩近似投影子空间跟踪方法估计信道并进行最大比合并,提高输出信干噪比。仿真结果表明,其误码性能优于匹配滤波器、传统Rake接收机、解相关Rake接收机和基于恒模算法的自适应接收机,且收敛速度较快、复杂度较低。     

伪码调相引信压制性干扰效果仿真

研究压制性噪声调频干扰对伪码调相引信的干扰效果.建立了接收机干扰效果仿真模型,分析了压制性噪声调频干扰对伪码调相引信干扰的机理,提出了基于相关器输出值过门限概率大小的压制性干扰效果评估方法,仿真分析了影响干扰效果的几个主要因素.仿真结果表明,采用窄带瞄准式干扰,增加接收机输入干信比,减小干扰带宽,提高载频瞄准度,可以增强干扰效果.     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-