基于临时锚节点的改进蒙特卡罗节点定位算法

针对当前移动无线传感器网络节点定位算法中存在的定位过程需要大量锚节点参考定位、定位成本过大、采样效率过低及计算能耗过大的问题,提出一种基于临时锚节点的改进蒙特卡罗节点定位算法。首先基于一跳范围内的锚节点和选择的普通节点作为临时锚节点进行定位,构建了节点的初始采样区域,以提高定位精度和定位覆盖率,然后通过新的重采样方式节省了大量重采样过程中的计算消耗。仿真结果表明:与基于RSSI(接收信号指示强度)的蒙特卡罗节点定位算法相比,提出的算法节点定位精度提高了约60%,在锚节点数量比较小的情况下大大提升了节点的定位精度和定位覆盖率。     

基于距离估计的无线传感网络移动节点定位研究

针对传统MCL算法定位精度低的不足,提出了一种基于距离估计的改进蒙特卡罗定位算法—DEMCL.首先根据网络连通度、锚节点信息和节点间的相邻关系估计目标节点与锚节点间的距离;然后利用该距离构建新的过滤条件加入算法的过滤阶段,以优化样本集和减小定位误差;最后以Matlab为工具对算法的定位性能进行仿真和分析.仿真结果表明:在同一环境下,与MCL算法和MCB算法相比,DEMCL算法能保证更高的定位精度,同时减少了无效定位的节点数目,网络覆盖率可达到98.83%.     

无线传感器网络节点定位算法分析

在各种无线传感器网络应用中,无线传感器节点的精确定位非常关键。在阐述了节点定位问题的基础上,分析了三种典型节点定位算法:质心法、不定形(Amorphous)法和蒙特卡罗法,然后通过仿真实验对算法性能进行对比,研究节点密度、节点速度和采样个数等因素对定位性能的影响。实验结果表明,蒙特卡罗法的误差最小,且在锚节点密度大于1,未知节点密度大于6,取样个数超过50时达到最佳定位性能。     

基于局部采样模式的无线传感器节点定位

提出一种局部采样模式的无线传感器节点定位算法,首先在与锚节点进行通信的交叠区域采样,然后利用距离比例因子计算平均跳距权值,最后采用颜色差值序列对样本点进行滤波,得到节点的位置.采用仿真实验对算法的性能进行了测试,结果表明,相对其他无线传感器节点定位算法,该算法可以满足多目标的实时定位要求,定位误差大幅度降低,定位效果更佳.     

一种基于凸优化的WSN障碍环境下定位算法

针对传统DV hop算法定位精度较低及定位环境中物体阻碍信息传播导致节点定位失效的问题, 提出一种适用于障碍环境下的高精度定位改进算法. 首先引入一个考虑定位节点的最小跳数误差修正值, 通过该值筛选参与定位的锚节点, 进而优化锚节点的平均跳距; 然后利用三角函数结合两锚节点间的准确距离共同计算未知节点到锚节点的距离; 最后通过对未知节点的位置进行凸优化计算, 使得节点间的数据传播具有最优路径, 优化定位过程, 提高定位精度. 仿真实验结果表明, 改进算法不仅解决了在无线传感器网络障碍环境下难定位的问题, 还可有效提高未知节点的定位精度.     

基于Voronoi图的无线传感器网络节点定位改进算法

在基于Voronoi图的定位算法中,因使用了接收到锚节点的接收信号强度(RSSI)而影响定位精确性.本文对Voronoi图定位算法进行改进,修正了RSSI的大小顺序,充分利用了收到的锚节点信息,实现了减少Voronoi区域交集为空的可能性,增加了定位精确性,使该算法可以适用于非视距、anchor节点稀少的环境.     

改进型无线传感器网络的质心定位方法

针对传统质心定位算法定位精度受锚节点密度影响大,但锚节点成本高而不能大量使用的问题,采用移动锚节点,引入高斯马尔科夫移动模型对锚节点移动路线进行规划,使锚节点在待测区域内随机移动形成更多的虚拟锚节点,代替传统定位算法中的锚节点,提高了质心定位算法中对未知节点的覆盖率与定位精度.仿真结果表明,该方法有效且能应用于大型无线传感器网络定位.     

无线传感器网络中一种改进的DV-Hop定位算法

针对 DV-Hop 算法在无线传感器网络节点分布不均匀时定位误差比较大的问题,提出了一种针对 DV-Hop 的改进定位算法。该改进算法主要是利用 RSSI 测量技术增加锚节点;在给定约束下引入“可能存在区域”这一概念,并以该可能存在区域的面积作为目标函数,对未知节点的位置利用非线性共轭梯度法进行逼近,从而使节点定位误差达到最小。通过仿真验证了节点通信半径和锚节点比例对定位误差的影响,结果表明,该改进算法将节点定位精度提高了5％～10％。     

RSSI模型参数动态修正的协作定位算法

提出一种结合接收信号强度指示(RSSI)模型参数动态修正和协作定位的RSSI改进算法.首先,利用高斯滤波对RSSI值进行优化,根据锚节点间的距离和RSSI值动态修正RSSI模型参数;然后,利用共线度有效阈值选取适合定位的锚节点组,由加权三边定位法得到节点坐标;最后,引入协作定位,利用锚节点置换策略自适应地选取已定位节点进行升级,升级节点作为锚节点参与协作定位.实验结果表明:在相同的环境下,RSSI改进算法较其他算法能有效降低测距误差,提高未知节点的定位精度.     

无线传感器网络中DV-Hop定位算法的改进

针对无线传感器网络DV-Hop定位算法中节点个数较少时跳段距离估算误差大,及只有2个锚节点时无法定位等问题,提出了一种改进的DV-Hop定位算法.新算法综合了功率控制和计算全网平均每跳距离等措施,提高了跳段距离估算精度,降低了定位误差;同时针对只有2个锚节点时无法定位问题,采用了2个锚节点的定位模型.仿真实验结果表明,改进算法可以明显提高定位精度和定位覆盖率.     

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.