共面波导馈电的新型圆极化天线阵列

提出了一种新型共面波导(CPW)馈电的1×2圆极化阵列天线及改进后的2×2阵列天线.为了改善阵列天线的圆极化轴比带宽,将顺序旋转馈电技术与共面波导-槽线馈电网络相结合,设计了用于微带贴片天线的新型馈电网络.仿真与实测结果证明,该类型的馈电网络可以同时改善阵列天线的阻抗带宽与轴比带宽.实测结果表明,1×2线阵的阻抗带宽与轴比带宽分别为3.79%和16.41%.2×2面阵的阻抗带宽与轴比带宽分别为3.61%和10.83%.     

用馈电校正优化设计双馈点圆极化微带天线

该文提出用馈电校正的方法来改善圆极化天线的轴比性能.通过增加附加并联枝节改变双馈电点处信号幅度和相位的相对分布,抵消高次模辐射和馈电网络寄生辐射的影响,将高次模辐射和寄生辐射都考虑在内,来实现馈电校正.在X波段采用全波一体化优化方法设计出双馈点宽带圆极化微带天线.该文给出了仿真结果及实测数据.获得的实测结果为:中心频率为10GHz,电压驻波比小于2的带宽为33.85%,圆极化轴比小于3dB的带宽为22.4%.与校正前的结果相比,轴比带宽从16.2%提高到22.4%.     

共面波导馈电圆极化微带天线研究

对一种结构新颖的共面波导馈电圆极化微带天线进行了研究。天线的辐射单元采用两个方形贴片,简并分离单元分别附加在两个方形贴片的不同边沿,共面波导开路终端通过耦合对两个方形贴片进行馈电。整个天线具有对称的结构,抑制了共面波导中的偶模分量,产生了两个同旋向的圆极化辐射波。分析并设计了这种天线单元,天线的实测-10 dB回波损耗带宽达到11.6%,圆极化带宽达到1.86%,在前、后两个方向上均辐射左旋圆极化(LHCP)波。理论设计结果与实测结果吻合较好。     

正交缝隙耦合馈电宽带圆极化微带天线设计

为了实现圆极化微带天线的频带拓宽和增益提高,在缝隙耦合天线的基础上,设计了一种Ku频段正交缝隙耦合馈电的宽带圆极化微带天线。该天线以双层方形贴片为辐射单元,在拓展天线阻抗带宽的同时提高了增益;采用微带线结合正交左旋缝隙结构实现耦合馈电,通过优化缝隙结构改善了天线轴比特性。测量结果表明:阻抗带宽(VSWR2)和轴比带宽(AR3dB)分别达到22.5%和16.2%,轴比带宽内天线增益均大于9dBi。该结构天线以其简单的馈电设计为宽带圆极化微带天线设计提供了一定的参考价值。     

表面开槽的有机磁性圆极化微带天线

提出一种新式单点馈电的小型圆极化微带贴片天线 .首次采用有机高分子磁性材料实现圆极化微带天线 ,并在贴片表面开槽 .这两项措施使天线尺寸缩减约 78% ,圆极化带宽为 1.3% ,尤其是有机磁性基片的应用使天线驻波比带宽 (10 d B Return L oss)达 10 .1% (15 5 MHz) ,同时具有易调谐、制造公差要求低的特点 .文中给出数值分析与实测结果 ,证实了理论设计方法的有效性.     

国际海事卫星地面终端天线阵单元的设计

提供了一个详细的国际海事卫星地面终端天线阵单元的设计，该设计采用单馈点圆极化口径耦合的多层微带天线形式，使用低价格、低介电常数的泡沫塑料，以降低成本和拓宽天线的阻抗带宽。测量结果表明，天线的阻抗带宽(电压驻波比，VSWR≤2)和圆极化带宽(轴比AR≤3dB)分别达到18.8％和12.3％。同时，天线在1593MHz的增益达到9.4dBi。     

一种新型宽带圆极化UHF RFID读写器天线

针对超高频射频识别(ultra high frequency radio frequency identification,UHF RFID)技术的发展需求,设计了一款覆盖UHF RFID全频段(840-960 MHz)的圆极化读写器天线.天线采用简单的平面缝隙贴片结构,利用π型线耦合馈电,获得了良好的宽带圆极化性能.重点分析了天线的宽带圆极化辐射机理和双向圆极化波的形成过程.天线的仿真和测试结果表明,S11≤-13 dB的阻抗带宽为200 MHz,3 dB轴比(axial-ratio,AR)带宽达到175MHz,频段内增益均大于3.4 dBi,且顶点的右旋圆极化(right-handed circular polarization,RHCP)电平和左旋圆极化(left-handed circular polarization,LHCP)电平差值均大于17 dB,具有较好的宽带性和抗干扰能力.仿真结果和实验测试结果的一致性良好,满足了UHF RFID读写器天线宽频带、高增益的应用要求.     

一种用于产生OAM波束的集成圆极化天线阵列

提出了一种在S波段内产生轨道角动量(OAM)波束的集成圆极化微带天线阵列.天线采用同轴馈电的方式.为了获得良好的圆极化特性,利用CST软件对天线结构参数进行了仿真优化分析,最终确定天线整体尺寸为0.416λ_0×0.416λ_0×0.026λ_0,3-dB轴比带宽为3.79～3.85 GHz,S_(11)-10 dB的工作带宽为3.74～3.96 GHz.该天线结构简单紧凑,易于实现.天线阵列由6个相同的圆极化天线组成,相邻阵列单元沿顺时针方向旋转60°,通过仿真和实验结果得知,在对阵元进行等幅、等相位的馈电的条件下,该天线阵列能够产生模态l=-1的OAM波束,这能够有效避免复杂馈电网络结构的设计.     

导航终端双频圆极化天线的设计

设计了一款应用于北斗导航卫星系统(CNSS)和全球导航卫星系统(GNSS)的双频圆极化微带天线,该天线覆盖了1 258～1 278MHz和1 575～1 609MHz频段.天线采用了3dB电桥作为馈电网络,展宽了阻抗带宽的同时也实现了天线的右旋圆极化并提高了圆极化性能;另外为了抵消探针引起的感抗,在探针的顶层串联了电容能更好的实现阻抗匹配,有效地降低了天线的驻波比.通过HFSS软件建模仿真,结果表明,在带宽范围内天线的驻波比1.5;法线方向的圆极化轴比均1.3dB;高频段增益5.45dB,低频段增益5.7dB,辐射特性较好.     

用于射频识别的低旁瓣圆极化微带天线阵

介绍一种工作于2.45 GHz射频识别（RFID）读卡器微带天线阵的设计与测试结果.该天线结构简单,具有低旁瓣与圆极化特性.实测旁瓣电平为-23.2 dB,VSWR≤2阻抗带宽约130 MHz（2.44～2.58 GHz）.这些特性能较好地满足RFID天线的要求.     

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)

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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.