磁光调制法测量高双折射光纤拍长的灵敏度分析

基于法拉第磁光效应,研究在光纤拍长磁光调制法测试系统中,对于给定的磁隙宽度和磁场强度,起偏方式与检偏方式对拍长测试灵敏度的影响.通过理论分析发现,除了目前通常采用的线偏振光沿光纤双折射主轴注入结合渥拉斯顿棱镜45°检偏的测试方式之外,另有两种测试方式也可以得到最大灵敏度,一种是线偏振光45°注入结合渥拉斯顿棱镜沿轴检偏,另一种是圆偏振光注入结合渥拉斯顿棱镜沿轴检偏.最后一种实验方式不需要在入射端精确定位光纤的双折射主轴方向,能简化实验过程,避免角度调节引入的测量误差.     

扭转双折射光纤Sagnac干涉仪及电流传感

光纤固有和外界线性双折射是光纤电流传感实际应用的主要障碍。本文应用琼斯矩阵分析了扭转双折射光纤Ｓａｇｎａｃ干涉仪的偏振光干涉及电流传感,从理论上讨论了光纤线性双折射对Ｓａｇｎａｃ电流传感的影响,并指出为有效地抑制这一影响,要求的扭转速率约为２００ｒａｄ／ｍ的量级,此外,旋转Ｓａｇｎａｃ环丙输入端面使它们的本地坐标系间夹角满足τｚ＋δ＝（ｎ＋１）π可进一步减小上述影响。     

椭圆双折射光纤的琼斯矩阵和法拉弟效应分析

1 前言光纤中的磁光法拉弟效应,可用来发展测量超高压线路上大电流的光纤传感器,其重量轻、抗电磁干扰、绝缘性能好等优点已被普遍公认。为了使光纤中传输的偏振光的微小法拉弟旋转不至于被光纤固有的双折射所淹没,目前传感所用的光纤多为低双折射光纤。但在绕制安装光纤线圈时,由于不对称的应力、形变以及其它外界环境因素引起的、随机变化的附加双折射也将导致光偏振面的旋转,甚至淹没法拉弟旋转。因此,对光纤线圈的绕制安装提出了极其严格的要求。已有人提出一种新型光纤——扭转高双折射光纤。从偏振光学的角度看,该光纤呈现椭圆双折射。     

扭转椭圆双折射光纤的Mueller矩阵

导出由光纤双折射参数、扭转速率表达的扭转椭圆双折射光纤的Mueller矩阵。Mueller矩阵具有实二重简并的本征值１，求得对应的本征矢即扭转椭圆双折射光纤本征偏振态的Ｓtokes矢量。偏振方向沿光纤特征方向的线偏振光输入，将得到偏振方向不同的线偏振光输出。还讨论了扭转椭圆双折射光纤的椭圆偏振器等效等问题。     

高圆双折射光纤的分析与设计

本文对高圆双折射光纤的偏振特性作了分析，提出了一个能确定高圆双折射光纤保偏性能的特性参数．文中还给出了对线偏振光输入、出射光消光比满足一定设计值下高圆双折射光纤固有线双折射及弯曲半径与光纤扭转率之间的关系曲线．这些结果为这类光纤的设计及性能判定提供了理论依据．     

光纤磁场传感器对线双折射敏感度的分析

为了降低光纤磁场传感器中线双折射对系统输出的影响,提高测量系统的稳定性.介绍了基于法拉第磁光效应小型光纤磁场传感器的系统结构,利用琼斯矩阵对线双折射及入射起偏角对传感器输出特性的影响进行了推导与仿真.分析了系统对线双折射变化的敏感度大小与起偏角的关系,确定了最佳起偏角的范围.分析表明,当入射起偏角取一些特殊值时,能够将系统对线双折射变化的敏感度降到最低,提高了系统的稳定性和可靠性,为光纤磁场传感器的实用化设计提供了参考.     

利用泰勒展开式的光学电流互感器补偿方法和仿真研究

提出了一种全新的补偿光学电流互感器线性双折射效应的方法,即通过泰勒展开式得到光学电流互感器输出波形中线性双折射效应与波形形状之间的关系.分析了线性双折射效应对输出波形的影响,论述了线性双折射效应的具体补偿方法,推导了基于泰勒展开式求解线性双折射效应的具体过程,并对该方法进行了验证.该方法避免了对线性双折射效应δ的复杂建模,利用数学计算直接求取δ的值,计算过程相对简单而且计算量小.仿真实验表明,该方法具有很强的精确性和实用性,通过先分析线性双折射效应而后产生对光学电流互感器补偿的方法,既提高了系统的长期稳定性,又保证了补偿的实时性.     

线双折射对高圆双折射光纤电流传感器输出信号的影响

对采用高圆双折射光纤的电流传感器中光纤特性的不完善,如光纤中存在的固有线双折射及弯曲引入的线双折射,传感器输出信号受到的影响进行了详细的理论分析及数值计算,获得了线双折射影响传感器输出信号的数据及曲线,并提出消除光纤中线双折射对传感器输出信号影响的方法。这些结果对分析传感器实际测量结果,提高传感器稳定性及性能以及传感用高圆双折射光纤的设计等都有很大的实用和参考价值。     

光纤光栅中双折射致偏振相关特性

为了研究光纤光栅在横向压力作用下的双折射效应,讨论了光纤光栅中双折射所致的透射特性以及偏振相关特性的变化。通过仿真分析了起偏角对传输特性的影响,研究了双折射效应引起的光纤光栅偏振相关特性。利用传输矩阵法,仿真分析了光栅的参数、结构类型、光纤本征双折射和光栅中光致双折射对偏振相关损耗的影响,并利用邦加球分析了经光栅双折射作用的透射光偏振态的变化。结果表明,双折射的大小和偏振相关损耗以及第一斯托克斯参量之间存在单调递增关系。此结论为利用光纤光栅的偏振特性进行弱压力传感测量提供了基础。     

全光纤型圆偏振起偏器的工作原理及理论分析

提出了以高扭转率旋转应力型双折射光纤来实现手征光纤光栅,并进而实现易于在线制成的全光纤圆起偏器.采用耦合模理论分析表明,以小于1mm的扭转周期旋转领结光纤或熊猫光纤可以实现圆起偏器.与已有的基于特殊光纤的手征光纤光栅不同,旋转光纤基于商用应力高双折射光纤,容易与普通光纤连接.耦合模分析还揭示了这类由旋转光纤形成的手征光纤光栅中圆偏振模相耦合的偏振选择机理和实现起偏器的必要条件.数值分析表明,对数值孔径为0.1865、拍长为1.25mm的熊猫光纤以右手螺旋方向进行旋转,当旋转周期和光纤长度分别为0.375mm和33.2mm时,该起偏器在谐振波长1550nm处输出左旋圆偏振光.     

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.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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)

正~~     

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.