基于水声矢量传感器阵的波达方向估计

推导了基于水声矢量传感器阵的Bartlett和Capon空间谱的解析表达式，并与标量传感器的空间谱相比较，分析了基于矢量传感器阵的两种DOA估计方法对阵列定向性能的改善，并给出了数字算例。     

MUSIC算法结合小生境遗传算法的电磁矢量传感器波达方向估计

当最大似然估计法和MUSIC算法求解矢量传感器阵列问题时,存在多维谱峰搜索的困难。采用一种小生境遗传算法用于矢量传感器阵列的MUSIC算法的多谱峰搜索。通过实验仿真,验证了小生境算法的有效性。仿真结果表明,基于遗传算法的MUSIC算法得到的角度估计均方根偏差性能比ESPRIT算法要差,而在均方根标准方差方面,基于遗传算法的MUSIC算法则比ESPRIT算法要好。     

基于角信号子空间的波达方向估计方法

常规多信号分类(MUSIC)在估计信号或噪声子空间时未利用阵列的方向矢量信息.为改善波达方向(DOA)估计性能,提出一种新的角信号子空间概念.首先,由Gram行列式和超维空间中多面体体积公式,给出常规MUSIC方法的几何解释.其次,利用阵列响应矢量扩展观测数据矩阵,在每个搜索方向由增广数据矩阵的奇异值分解获得角信号子空间估计.理论分析表明,常规MUSIC零谱相当于超维空间中由阵列观测数据矢量和搜索方向矢量决定的多面体体积.仿真实验表明,利用角信号子空间能够较明显地改善DOA估计性能,特别是信号相关、信噪比较低以及快摄数较小的情况.     

一种基于声矢量传感器阵列的二维来波方向和阵列增益联合估计算法

基于声矢量传感器阵列的二维来波方向估计是水声通信的关键技术,但阵列增益的不一致性将影响来波方向估计性能.基于子空间分解,提出一种阵列增益和来波方向的联合估计算法,其中来波方向利用旋转不变性求解,阵列增益利用子空间正交性求解.来波方向和阵列增益以迭代方式求解.仿真结果显示了算法的有效性.     

四四元数域低秩逼近及其在矢量阵列波达方向和估计中的应用

提出了新的多元数概念——四四元数,以及四四元数框架下特征分解和奇异值分解等信号处理领域常用的矩阵运算新规则.在此基础上提出了四四元数矩阵的一种低秩逼近算法,并将其用于矢量传感器阵列信号建模及波达方向(DOA)估计中.结果表明,四四元数特征分解及奇异值分解能获得比现有方法更好的低秩逼近性能,基于四四元数模型的矢量传感器阵列信号DOA估计算法,在资源占用、子空间逼近以及对模型误差的鲁棒性等方面均明显优于传统算法.     

四四元数域低秩逼近及其在矢量阵列波达方向估计中的应用

提出了新的多元数概念——四四元数,以及四四元数框架下特征分解和奇异值分解等信号处理领域常用的矩阵运算新规则．在此基础上提出了四四元数矩阵的一种低秩逼近算法,并将其用于矢量传感器阵列信号建模及波达方向（DOA）估计中．结果表明,四四元数特征分解及奇异值分解能获得比现有方法更好的低秩逼近性能,基于四四元数模型的矢量传感器阵列信号DOA估计算法,在资源占用、子空间逼近以及对模型误差的鲁棒性等方面均明显优于传统算法．     

网络传感器阵列目标定距定向的影响因素研究

基于声阵列信号时延估计、双曲线目标定位方法,推导了平面任意三元阵目标定向、定距计算公式,并采用该公式对声传感器阵列定位应用中的时延估计误差、阵列孔径大小、阵元布放误差等因素造成的目标定距、定向误差进行了计算和分析研究. 计算结果表明:在同样的初始误差条件下,采用大孔径阵列可以显著降低定距及定向误差,且定向精度的需求比较容易满足而定距精度的需求较难满足.      

刍议异步电动机转子磁场定向矢量控制系统

以转子磁场定向的矢量控制系统已经广泛应用于高性能的工业场合。本文阐述了异步电动机转子磁场定向矢量控制需要解决的问题;无速度传感器矢量控制(SVC控制)的自适应转速估计以及DSP系统的实现。     

人工神经网络对电子鼻性能的影响

电子鼻原型由4个气体传感器组成的阵列和人工神经网络识别软件组成,可识别不同品牌的白酒.以它为例,研究了3种人工神经网络,即反向传输网络(BPN)、学习矢量量化网络(LVQ)和概率神经网络(PNN)对电子鼻性能的影响.结果表明,在需要精细识别时,虽然传感器阵列对白酒的响应谱的差别是电子鼻识别的基础,但是人工神经网络结构和算法包括相关训练参数的选择对决定电子鼻的性能也有重要的作用.比较而言,学习矢量量化网络在分类能力和训练成本方面更胜一筹,而概率神经网络则在计算负载和易用性方面更好一些.     

基于DSP的无位置传感器永磁同步电机矢量控制系统

讨论了一种采用DSP芯片TMS320LF2407实现无传感器永磁同步电机转子磁场定向矢量控制的方案。文章简单介绍了永磁同步电机的数学模型和矢量控制的基本原理,给出了在无位置传感器的情况下电机转子位置信号的确定方法,讲述了采用id=0的对凸极式转子磁路结构的无传感器永磁同步电动机的控制方法,说明采用高速数字信号处理器易于实现复杂的矢量控制算法,可以有效的解决电机的强耦合特性。     

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.