二维三次非线性相位耦合的切片谱分析

针对二维三次非线性相位耦合问题，定义了特殊四阶累积量及相应的四阶累积量切片谱，并利用四阶累积量切片谱方法对二维三次非线性相位耦合进行了分析。利用复数信号的四阶累积量有2^4种定义方式这一特点，分别利用两种特殊的四阶累积量的定义。该方法有效地估计出高斯噪声背景下的参与二维三次非线性相位耦合的谐波频率和耦合产生的谐波频率。从而识别出系统的非线性。仿真实验验证了该算法的有效性。     

二维谐波频率的频域非线性预滤波估计方法

根据谐波信号在带噪信号的频谱中表现为异常脉冲这一特性,提出了一种新的有色噪声背景下二维频率估计方法.利用二维滑动中值滤波器能够滤除异常点的能力,提取噪声频谱,消除有色噪声对信号的影响.将有色噪声转化为白噪声,然后利用高分辨率的二维ESPRIT方法估计信号频率.在不需要知道有色噪声任何统计特性的情况下,该方法对有色噪声具有很强的普适性,仿真实验表明,在信噪比达到-18 dB时,该算法仍然能够准确地估计频率.且由于算法中仅利用了二阶统计量,更便于实现.     

相关乘性和加性噪声背景下的二维谐波恢复

针对乘性噪声和加性噪声均为零均值,且乘性噪声之间相关,乘性噪声和加性噪声之间也相关,这种复杂噪声背景下的二维谐波恢复问题,利用二维循环统计量方法进行了研究.提出了二维噪声互可混的概念,用来体现多个二维噪声之间的相关关系;定义了特殊的二维四阶时间平均多矩谱来估计信号频率.仿真实验证明了算法的有效性.     

二维正弦信号频率估计的ESPRIT方法研究

为了在噪声背景下估计二维正弦信号的频率,并获得较高的估计精度,给出了二维相关阵的大特征值所对应的主特征向量,位于由信号向量张成的信号子空间的结论,并因此提出了一种新的基于最大特征值所对应的第1特征向量的二维谐波频率估计ESPRIT(Estimation of Signal Parameters Via Rotational Invariance Techniques)方法.该方法用此第1特征向量构造一个特殊矩阵代替MEMP(Matrix Enhancement and Matrix Pencil)方法中的数据矩阵,进一步用二维ESPRIT方法来估计谐波频率.该方法依赖于信号子空间,对噪声和数据长度敏感性小,同时它不需进行谱峰搜索,可以得到较高的估计精度.同时给出了较为简便的频率配对算法.仿真实验证明了算法的正确性.     

基于盖氏圆与TAM的电力系统谐波检测

电力系统中谐波检测是无功补偿、谐波滤除等电能质量分析与控制的前提。针对传统电力系统中谐波检测方法存在的问题,结合盖氏圆和TAM算法进行谐波检测。该算法以信号空间为模型,首先用盖氏圆检测出信号源数,然后结合信号子空间和噪声子空间的正交性以及子空间的旋转不变性,估计出信号的频率,最后由全最小二乘法(TLS)计算得到信号的幅值。仿真实验与实际数据分析结果表明:该方法速度快、精确度高,具有一定的应用前景。     

利用高阶统计量恢复二维谐波

基于高阶统计量提出了一种频域恢复频率、时域恢复幅度的时频域相结合的二维谐波信号的恢复方法。该方法由于使用了高阶累积量，因此不再受背景噪声为高斯白噪声的限制，可应用于高斯噪声中二维谐波信号的恢复。仿真实验证明了该方法的可行性     

非平稳噪声环境下LFMCW信号恒虚警检测算法研究

为了提高电子侦查系统中对非平稳噪声环境下线性调频连续波信号的实时检测能力,提出了一种对信号进行分段检测的低复杂度算法.根据假定最大调频斜率设定窗函数宽度,将截获信号均匀分割为多个序列,在每个时间序列内建立短时谐波模型,并采用多个正交窗函数对信号进行加权离散傅里叶变换.在此基础上,推导出符合F分布的检测模型.该模型与噪声功率无关,因此检测前无需统计噪声功率,可对非平稳噪声环境下的信号进行恒虚警率检测.仿真分析了影响该算法性能的参数,通过与单窗口检测算法对比,验证了该算法在非平稳噪声环境下优良的检测性能.      

高精度介质损耗角实时在线测量方法

为提高电气设备介质损耗角的测量精度,利用最优相关滤波法提取基波信号,通过短时傅里叶变换（STFT）插值谐波方法,抑制长频谱泄露的影响。仿真结果表明,最优相关滤波法可以克服加性噪声和调制性噪声的影响,在低信噪比情况下,能够有效消除噪声并检测出有用信号,提高STFT加窗谐波分析法的计算精度。系统频率在49.5～50.5 Hz时,该算法仍能保持较高的计算精度,且受频率变化影响较小。该方法能有效提高信号的分辨能力和准确度。     

复杂噪声中基于累积量的二维DOA估计

针对自相关算法的局限性,研究了复杂环境(乘法与加法观测噪声共存时)中,通过高阶累积量对二维DOA估计的问题.算法能同时确定目标的仰角与方位角;高阶累积量使得算法能够更加有效抑制消除乘法噪声.该方法对任何平稳的加性与乘性噪声均不敏感,因而具有较大的实用性.     

子空间分解法在声目标特征提取中的应用

目的　研究用于识别直升机目标声信号的特征提取方法。方法　通过对直升机声信号频域特性分析,采用基于子空间分解的多重信号分类法(MUSIC)算法提取信号谐波频率作为目标特征,利用子空间分解将观测数据分解为信号子空间与噪声子空间的特点,抑制噪声干扰,提高识别能力。结果与结论　对实测的直升机声信号谐波频率提取结果表明,子空间分解方法提取目标频域特征是可行的,用MUSIC算法提取谐波频率值是有效的。     

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.