基于AWR1642的汽车防撞雷达设计

防撞雷达在智能汽车的环境识别中具有不可替代的作用,介绍了一种基于AWR1642的汽车防撞雷达设计,通过对4通道接收机接收到的回波信号,在时域上使用FFT算法对障碍物进行距离探测,空域上使用DBF算法进行方位探测,从而得到障碍物的距离和方位信息.根据AWR1642传感器提供的技术参数提出了本系统的主要技术指标,并加以论证.仿真实验结果表明,该系统能满足测距、测角的精度要求.     

混沌同步系统降噪方法及其在滚动轴承故障诊断中的应用

提出了一种基于混沌同步系统的降噪方法,将其应用于滚动轴承振动信号的前期处理,并结合功率谱密度进行故障诊断.分析Chua电路混沌同步系统的降噪机理,讨论系统处于不同运行状态时,输入信号对相空间运行轨迹的影响;搭建混沌同步系统降噪模型,分析其检测特性,并与其他方法进行比较;将滚动轴承不同损伤模式下测得的振动信号输入该模型,比较振动信号和同步误差信号的时域波形和功率谱密度,并通过峰值查找,匹配对应的故障特征频率.新方法利用了混沌系统的噪声免疫性和可同步性,避免了现有方法参数设定复杂和运行状态判定困难的问题.结果表明该方法可有效提升被测信号的信噪比,能与传统方法结合形成新的故障诊断方法.      

空域相关滤波法在突变检测中的应用

为有效检测含噪信号突变点,研究了小波变换的空域相关滤波算法,并应用其分析和处理突变信号.应用Matlab分别对信噪比为15.7133 dB、10.1305 dB、5.7688 dB含噪突变信号进行仿真,结果证明,空域相关滤波算法在不同信噪比下具有良好的适应性.在信噪比为15.7133 dB时,分别运用小波阈值滤波算法和空域相关滤波法对突变信号进行处理,得到平均重构误差分别为1.1636和0.93906。证明了空域相关滤波法在突变点检测中的优越性.     

基于小波空域相关的船舶轴频电场检测方法

为了提高对船舶水下轴频电场的远程探测能力,在充分分析实验室轴频电场信号的基础上,提出了一种基于小波空域相关的船舶轴频电场检测方法.首先使用小波空域相关对噪声和信号进行分离,并给出一种针对轴频电场的噪声阈值估计方法;然后,提取信号特征频率范围内的能量作为特征值,对信号进行滑动功率谱检测.对比分析结果表明,该算法在低信噪比情况下具有更高的稳定性和更好的检测效果.

     

DRM无源雷达多径杂波的分载波空域抑制

鉴于数字调幅广播（DRM）无源雷达面临严重的多径杂波问题,建立了该无源雷达阵列信号模型,提出了一种基于分载波空域处理的多径杂波抑制方法.该方法先将DRM无源雷达阵列接收的时域信号经去保护间隔和傅里叶变换（FFT）之后,通过对各载波信号分别求取干扰协方差矩阵和空间自适应系数以滤除直达波和多径杂波.分载波空域处理方法综合利用了多通道空域信息及同一载波下直达波和多径杂波的时域相关性,降低了杂波抑制的空域自由度要求,提高了杂波抑制能力,克服了常规空域处理方法自由度不足或杂波噪声比低导致的杂波零陷深度不够等缺点.理论分析和仿真结果表明了该算法的优越性.     

基于调频电台非合作式双基地雷达试验系统研究

简要介绍了基于调频电台非合作式双基地雷达试验系统的组成,解决了两个主要直达波对消和目标检测问题。使用基于NLMS方法的非因果滤波器完成阵列多通道的时域均衡, 通过时域、空域联合处理,对消了比噪声强80 dB以上的直达波信号,对民航飞机的探测距离超过300 km。试验验证了该算法的实用性。     

矢量水听器阵列矩阵空域预滤波MUSIC算法

针对矢量水听器阵列多重信号分类(MUSIC)算法分辨率低这一缺点,提出了矢量水听器阵列矩阵空域预滤波MUSIC算法.该算法充分利用矩阵空域滤波器输出数据保留阵元域的特性,通过设计一个空域矩阵滤波器对矢量水听器阵列数据进行预处理,抑制阻带扇面的干扰与噪声,且尽量保证通带扇面的信号无失真通过,然后利用MUSIC方位估计进行处理.仿真结果表明:该算法可以抑制通带扇面外干扰与噪声,通带内目标分辨信噪比门限可提高3dB.     

光纤周界报警系统中基于时域的信号特征参数提取方法

为提高光纤周界报警系统对入侵事件报警的实时性和准确性,设计了一种高效的基于时域的干涉信号特征参数提取算法,并搭建了迈克尔逊光纤干涉仪原理的光纤周界报警系统用以验证该算法.经过对敲击、切割、攀爬和刮风等四种典型扰动事件的干涉信号特征参数的提取,并输入模式识别系统进行事件甄别,实验数据表明系统的报警准确率达到90％以上.     

基于四阶累积量的近场源时-空域三维参数估计法

研究了近场源的频率-方向角-距离的三维参数估计问题,并针对已有方法估计精度较低的问题,提出了一种利用四阶累积量和信号的空域和时域信息估计信源的频率-方向角-距离参数的方法.该方法扩展了阵列的孔径,提高了算法的估计性能.仿真实验证明,当信噪比为0时,该算法仍然能够正确估计信源的参数.     

基于导航卫星反射信号的距离-多普勒图信噪比增强算法

利用全球导航卫星系统(global navigation satellite system,GNSS)与地基接收机构成的双基地雷达探测水上目标,是监测水上交通的新兴手段。利用由地球静止轨道(geostationary earth orbit,GEO)卫星反射信号生成的距离多普勒(range-Doppler,RD)图来实现目标探测。为了提高RD图中运动目标回波信号的信噪比,提出了一种增强回波信号能量的算法。该算法首先将相邻距离元和多普勒元上的回波信号通过距离补偿和多普勒补偿搬移到弱回波信号的位置,然后通过信号累加提高回波信号的能量,从而达到增强信噪比的目的。描述了探测长江货轮的实验,实验结果表明经增强算法处理后,运动目标回波信号的信噪比平均提高了4 dB左右。这一结果验证了利用北斗GEO卫星探测水上目标的可行性。     

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…     

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。     

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     

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     

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

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.