锥扫LFMCW雷达信号处理方法的研究

基于线性调频连续波及圆锥扫描理论,研究锥扫线性调频连续波雷达信号处理方法.针对回波信号的特点,将频域法运用于锥扫线性调频连续波信号.论证了该信号可以在距离高分辨率的基础上进行有效测角,分析了信号处理时频谱泄漏对系统造成的影响,并对泄漏进行了补偿.计算机仿真结果表明,该方法可应用于跟踪雷达的信号处理中.     

锥扫LFMCW雷达信号处理方法的研究

基于线性调频连续波及圆锥扫描理论,研究锥扫线性调频连续波雷达信号处理方法.针对回波信号的特点,将频域法运用于锥扫线性调频连续波信号.论证了该信号可以在距离高分辨率的基础上进行有效测角,分析了信号处理时频谱泄漏对系统造成的影响,并对泄漏进行了补偿.计算机仿真结果表明,该方法可应用于跟踪雷达的信号处理中.     

线性调频连续波雷达的距离估算

针对线性调频连续波(LFMCW)雷达系统的结构特点,推导了LFMCW雷达的距离方程,证明了LFMCW雷达作用距离的四次方与其发射信号的时宽带宽积成正比,为LFMCW雷达的设计提供了工程计算的依据.     

宽带调频连续波近程多站雷达系统对细柱状目标定位研究

首次将宽带调频连续波发射波形引入近程多站雷达系统,利用宽带调频连续波雷达信号的高距离分辨率分析了近程细柱状目标几何中心定位的性能,提出了利用回波频谱估计细柱状目标长度的方法并给出了计算表达式,对系统性能进行了计算机仿真,所得结果对工程实践有一定的指导意义     

调频连续波雷达自旋目标干涉三维成像方法

相比脉冲体制雷达,调频连续波雷达具有功耗低、成本低、重量轻等优点,发展前景广阔,同时雷达三维成像技术可为目标的分类识别提供重要的特征信息。但是自旋目标在调频连续波信号条件下会产生一维距离走动以及回波相位的改变,这对干涉三维成像产生了影响。针对自旋目标在线性调频连续波雷达中的干涉三维成像技术进行了研究,分析了自旋产生的回波调制效应与相位变化,结合分析所得的调制前后目标在距离 慢时间像上微动特征的变化关系与扩展Hough变换提取的微动参数,解决了干涉三维成像中由于回波调制效应导致的目标坐标畸变问题,提出了基于调频连续波雷达的自旋目标干涉三维成像的具体处理方法。仿真实验证明,所提方法有效提高了自旋目标的干涉三维成像质量。     

一种LFMCW雷达目标距离提取方法

在阐述FFT方法、最小二乘曲线拟合方法和雷达信号特点的基础上,将BP网络应用于线性调频连续波雷达系统目标距离的信号处理中,用雷达数据对构造的BP网络进行了训练和测试。仿真结果表明,该方法在训练对象足够充分的情况下可以适应较大范围内测量,在无噪或低噪声的情况下,可以获得较高的测量精度,是一种对LFMCW系统信号处理的有效方法。     

一种LFMCW雷达目标距离范围的划分方法

在采用对称三角波作为调制信号的线性调频连续波(Linear Frequency Modulated Continuous Wave,LFMCW)雷达系统中,雷达传感器前端产生的三角调制波泄漏信号严重影响远距离目标的测量结果。因此有必要对待测目标进行范围划分。传统的距离划分是在对回波信号进行频谱分析之后进行的。提出的基于相似度匹配法能够在未对信号进行频谱分析之前,根据与标定目标预先计算的阈值作比较,得出目标所在距离范围,并针对实际系统设计实验方案,验证该方法的可行性。     

波形对气象雷达探测的影响研究

对于雷达系统来说,发射波形决定了雷达系统的信号处理方式,因此发射的波形对于雷达系统来说十分重要。常规的气象雷达波形单一,在气象探测中存在不足;基于这个问题,从改变气象雷达波形的角度出发,研究波形对气象雷达探测的影响。分别从脉冲压缩后主旁瓣比、波形对雨量的衰减程度以及多普勒效应方面对三种波形进行仿真和分析,得出当降雨强度为中雨以上和小雨时分别采用线性调频波形信号和13位巴克码波形信号进行探测较为理想,当降雨强度在短时间内变化较大时则采用组合波形信号探测较为合适。     

无人机微多普勒特征实时提取的FPGA实现

小型无人机具有高度低、速度慢、机动性强和可悬停等特点,给雷达探测无人机目标带来了很大的困难.为解决此问题,本文立足于实际的线性调频连续波(LFMCW)雷达系统,利用现场可编程逻辑门阵列(FPGA)的并行处理能力,通过对数据进行流水线处理和乒乓操作来替代传统的串行处理器实现动目标指示(MTI)和动目标检测(MTD)算法,...     

基于小孔径超视距目标探测的OFDM-LFM发射波形设计

针对传统天波超视距雷达接收阵列孔径大的问题,提出一种基于小孔径的超视距目标探测方法。分析了阵列孔径减小后信号接收与处理的性能损失,在此基础上采用正交频分复用线性调频信号,从发射信号设计方面提升系统性能。首先对信号进行建模,重点提出一种基于凸优化的脉压信号峰值旁瓣抑制算法,建立了优化模型并进行求解。仿真表明,采用正交频分复用线性调频信号可以提升距离分辨率,采用凸优化的算法后脉压峰值旁瓣为-26.28dB,旁瓣电平平均值小于-50dB,距离门内和距离门外噪声/干扰的抑制能力得到提升,改善了小孔径超视距目标探测的处理性能。     

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.     

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.     

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.     

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.     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.