传输法测量电容器的高频参数

本文详细地讨论了用传输法测量电容器的高频参数。我们提出和试验了一种传输系统,用集总参数功率分配器和矢量电压表可以在极低频到1000兆赫频段内方便地测得固定电容器的阻抗频率特性和高频参数,其测试范围尚可扩展到更高的频段。采用这种集总参数功率分配器传输系统可以测量低至10~(-4)毫亨的固有电感量和10~(-2)欧的等效串联电阻值,并且具有良好的重复性。这一系统已被采纳为我国测量固定电容器高频参数的部定标准。     

双频段无线电能传输线圈的宽频建模

为了研究双频段磁耦合谐振式(MRC)无线电能传输(WPT)系统不同频段的传输性能,建立了双频段MRC-WPT线圈的宽频等效电路模型对其谐振频率进行计算和预测;并计算系统在不同频段的正向传输参数。首先测量双频补偿电路的阻抗频率特性,应用矢量匹配方法对测量所得的离散点进行有理数逼近,通过阻抗综合理论建立双频补偿电路的宽频等效模型;然后将其接入原始单频线圈的部分元等效电路构成双频段MRC-WPT线圈的宽频等效电路。最后,搭建了双频段MRCWPT系统的实验平台。结果表明了建模方法的正确性。     

H型液压滤波器的合理应用

为减轻液压系统压力脉动,提出H型液压滤波器,详述了其工作原理和滤波理论。基于运动微分方程和流体连续方程,建立了滤波器的动态响应模型,研究了H型液压滤波器各参数对滤波效果的影响。仿真与试验结果表明:H型液压滤波器并入系统后,共振频率处系统阻抗达到局部最小,中、低频段产生一低阻抗区,且频率明显低于滤波器共振频率,使得设计小体积频率滤波器成为可能;在共振频率处颈径和颈长适中时,体积越大,则阻抗越小,滤波效果越好。     

基于矢量拟合的直流输电线路建模

针对线路传播过程中的频变现象,采用矢量拟合法进行频变直流线路建模并对其建模影响因素进行分析。通过对线路进行阻抗频率特性测量,采用矢量拟合法对测量得到的离散点进行有理函数逼近,拟合的带宽为10~0～10~(6 )Hz,得到考虑频变特性的直流线路数学分析模型,以此为基础建立其3阶线路等效模型,并对线路建模效果的影响进行了深入分析。所建立的线路等效模型与在基于实际参数的PSCAD/EMTDC(power systems computer aided design)软件中建立的直流线路仿真模型进行对比分析,其误差最大处不超过10~(-2),且在故障行波主要传输频段10~3～10~5 Hz内具有很高的精度。其结果验证了该方法具有良好的精确性和适用性。     

电机宽频等效电路模型的快速建模方法

提出了电机宽频等效电路模型的建模方法。通过测量获得电机端部阻抗幅频特性,根据幅频特性的第一个谐振点信息,将幅频特性曲线划分为若干个区域,每个区域用一个谐振单元等效,构建出电机宽频等效电路拓扑;每个谐振单元的R、L、C参数通过该区域的谐振点和任一非谐振点的频率和对应的阻抗值计算获得。用该方法建立了直流电机和交流电机的宽频等效电路模型,并在Saber软件中进行了仿真。将直、交流电机宽频等效电路模型的阻抗幅频特性仿真结果分别与测试结果和参考文献的仿真结果进行了对比。在直流电机端部阻抗特性拟合频段0.1~50 MHz的范围内、交流电机端部阻抗特性拟合频段0.1~40 MHz的范围内,验证了电机宽频等效电路模型的正确性与可行性。     

岩石复电阻率测量中的电极效应

复电阻率是电磁勘探描述地下岩石电性的重要参数之一。根据电磁勘探频段,实验室内复电阻率测量的低频段通常达到10~(-2) Hz。为避免测试电极与岩石的宏观结构形成电极极化影响岩石微观结构的研究,通过电化学理论结合复电阻率实验研究了不同电极材料对流体、岩石的复电阻率测试中的电极极化特性。结果表明,测试岩石在低频段容易受以物质传递为主的电极极化影响;电极极化同时受电极材料、电极附近流体矿化度和温度、被测岩石阻抗等因素的影响;最后,分析和讨论了减小或消除电极极化影响的方法,为准确测量岩石复电阻率并用于微观结构分析提供了理论和实验基础。     

紧凑型多陷波超宽带滤波器的设计

针对传统带阻单元构成滤波器存在陷波深度不足和阻带抑制较差的问题,提出一种加载开路枝节的多陷波超宽带滤波器。基于开路枝节线和阶跃阻抗谐振器理论,通过在超宽带滤波器多模谐振器上引入一对折叠开路枝节线产生2个陷波频段,这种特殊枝节实现的陷波抑制能力更强;在超宽带结构下方耦合阶跃阻抗谐振器产生第3个陷波频段,陷波深度更好。最终实现超宽带带通滤波器的中心频率为6.6 GHz,陷波频段相对带宽约为134%。仿真与实测结果表明,该滤波器工作带宽为2.2~11.2 GHz,实现了2.8~4.4 GHz,6.2~6.8 GHz和8.8~9.8 GHz 3个频段的陷波特性,可有效滤除C波段和WLAN频段信号对超宽带通信系统的干扰。满足超宽带系统对陷波滤波器插入损耗和带外抑制的要求。     

Fe63.5Cr10Cu1Nb3Si13.5B9非晶和纳米晶合金的巨磁阻抗效应

研究了退火处理引起结构上的变化对Fe63.5Cr10Cu1Nb3Si13．5B9非晶合金磁阻抗效应的影响,实验结果的分析表明,在测量的频段(0．2～10MHz)内巨磁阻抗效应可归因于偏置场引起的环向磁化率的改变,良好的软磁性是获得大的磁阻抗效应的重要条件．     

特高压输电线路的大截面导线微风振动特性

为了掌握用于特高压输电的大截面导线JL1X1/G2A-1520/125-481的微风振动特性,对该型导线建立微风振动控制方程,编程计算了8~80 Hz频段中16个等间距频率点处导线的双振幅值、允许振幅、单位功耗等风振特性,并利用波腹处的最大振幅确定了导线悬挂点在各频率点的动弯应变与动弯应力。研究发现:在自阻尼振动情况下,该型号导线双振幅值随频率增加先增加后降低,在20 Hz附近达到最大值,当振动频率为20~40 Hz时,导线的振动幅值超过其允许幅值;导线的单位功耗随振动频率的增加先增大其后降低,在40 Hz附近达到峰值;在20~40 Hz频段,导线的动弯应变与动弯应力水平偏高,超出了容许值。与普通截面导线的10~20 Hz危险频段相比,大截面导线JL1X1/G2A-1520/125-481的危险频段后移至20~40 Hz,此型号导线的防振消振方案应该重点考虑20~40 Hz频段。     

ERT/ECT技术电学特性与激励频率研究

电学层析成像技术包括ERT、ECT和EMT,但其对应系统的适用被测对象不同。为使电学层析成像技术更好地适用于多相流测量问题,采用数值仿真的方法,研究了多相流介质的电导率和介电常数对电学敏感场分布的影响,并且比较了不同电学特性参数介质场的频率特性。结果表明,电学层析成像系统的类型和激励频率可根据被测对象的电学特性参数决定。电导率较大(10~(-3)S/m)时采用电阻抗实部成像,选用ERT系统;电导率极低(10~(-5)S/m)且介质间介电常数相差较大时采用电阻抗虚部成像,选用ECT系统;且系统激励频率可选范围随电导率的增加而增大。最后将仿真结果与4种不同电导率被测场的实际测量数据进行对比验证,验证了仿真结果的正确性。     

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.