一种宽频带双极化印刷偶极子基站天线

设计了一种适用于LTE基站天线系统的宽频带±45°双极化辐射单元。该辐射单元采用微带巴伦结构,用双倒L形微带馈线进行耦合馈电,并对该微带馈线进行切角、增加横向枝节、改变开路枝节宽度有效地扩展了天线的带宽。仿真及实测结果表明,在1.7~2.7 GHz频带内,该辐射单元的电压驻波比(voltage standing wave ratio,VSWR)小于1.4,隔离度大于25dB,相对带宽超过45.4%。利用该辐射单元组成八单元阵列天线后辐射参数良好,水平面半功率波束宽度稳定在65°±5°,主极化前后比大于25 dB,轴向交叉极化比大于18 dB,基本能满足移动通信基站天线的指标要求。     

一种新型的宽带双极化基站天线

提出一种新型的宽带双极化辐射单元,该辐射单元的辐射臂由普通方形对称振子的辐射臂向内折弯构成,形成一个附加小U型,它可以展宽带宽,且缩小辐射单元的口径面积;采用内部相向开口的半开放式巴伦结构,并用双倒L型耦合馈电,改善了隔离特性和波束收敛性。利用这种辐射单元组阵,形成四单元的基站天线,仿真结果表明,1.7~2.7 GHz频段内,该辐射单元的电压驻波比(voltage standing wave ratio,VSWR)小于1.4,隔离度小于-30 dB;同时,利用该辐射单元组成的四单元基站天线辐射参数优良,水平面半功率波束宽度达到65°±5°,±60°交叉极化鉴别率小于-12 dB,前后比小于-25 dB。     

EBG 结构宽频带双极化基站天线的设计

介绍了一种新型的宽频带双极化辐射单元,该辐射单元采用了新型的电磁带隙(electromagnetic bandgap,EBG)结构加载,该EBG结构结合对称振子进行一体化设计,缩小了辐射单元的高度,其高度约为中心频率的0.16个波长.利用这种辐射单元组阵,形成四单元基站天线.HFSS仿真结果表明,在1.71-2.69 GHz频段内,该辐射单元的电压驻波比(voltage standing wave ratio,VSWR)小于1.5,隔离度大于22 dB.同时,组阵后的四单元基站天线辐射参数良好,水平面半功率波束宽度58.1°-72.1°,轴向交叉极化比大于21 dB,前后比大于20 dB,基本能够满足移动通信对基站天线的使用要求.     

一种电磁脉冲测量超宽带大功率TEM喇叭天线

设计并加工测试了一款适用于瞬时大功率电磁脉冲测量的超宽带TEM波喇叭天线。该天线的馈电部分采用同轴宽带巴伦,辐射单元由两片平滑、渐变的金属曲面组成。为了实现天线的超宽带特性,同轴巴伦和辐射单元均采用指数渐变的形式。而为了提高天线的功率容量,将大功率同轴宽带巴伦和辐射单元直接相连。仿真和实测结果表明该天线在0.5~6GHz频率范围内,其电压驻波比VSWR≤2,平均增益Gain≥8d B,增益平坦性在±1d B之内,满足电磁脉冲测量的基本需求。     

P波段小型化锯齿缝隙超宽带天线设计

设计了一种P波段小型化超宽带天线。该天线采用微带线对五边形辐射单元进行馈电,接地板上蚀刻了锯齿形边沿的矩形宽缝。通过天线参数的仿真优化,最终实现了相对带宽约95%、尺寸为0.27λ×0.17λ(λ为低频点的自由空间波长)的超宽带P波段小型化印刷天线。仿真结果表明:天线的工作频带为300.5~848.8MHz,带内回波损耗均在-10dB以下,整个频段内天线的增益均在3dBi以上,天线为全向辐射。该天线具有平面结构,形状简单,易于共形的特征。最后制作了天线样件并进行了测试,测量结果与仿真结果吻合较好。     

C波段超宽带双极化微带贴片天线的设计

设计并仿真优化了基于L探针耦合馈电的C波段超宽带新型±45°双极化微带贴片天线,所设计的实现双极化采用的方法是两个正交L探针相互耦合并进行馈电,使得天线所承载的信道容量得到大幅度提升.借助Ansoft HFSS 15.0,完成对所设计的天线进行仿真验证,使得其重合阻抗带宽为38％,即在3.95～ 5.80 GHz时驻波比(voltage standing wave ratio,VSWR)小于等于2.同时,该天线在两个端口分别激励的情况下平均增益大于9.0 dBi,两个端口之间的隔离度大于22 dB,交叉极化电平小于-15 dB.该天线结构设计简单,可广泛应用于C波段超宽带无线收发通信系统.     

一款紧凑型超宽带MIMO天线设计

提出并设计一款使用相互垂直解耦结构的紧凑型超宽带MIMO天线.天线由4个耳朵型的平面单极子天线单元组成.在地板上延伸出的带有平行金属带的倒L型枝节,能够拓展天线的带宽,同时改善天线端口间的隔离度.仿真和测试的结果表明天线在3.1~10.6GHz的带宽内隔离度在-20dB以下.同时给出了天线的增益、效率、辐射方向图和相关系数.     

一种基于康托集分形的超宽带陷波天线的研究与设计

提出了一种共面波导馈电的超宽带陷波天线.该天线采用康托集分形辐射单元,有效增加天线的阻抗带宽,使所设计的天线满足超宽带通信的需求.为了避免超宽带天线与传统的窄带系统之间的干扰,在共面波导接地面的顶部刻蚀一个U形槽,从而在5.1～5.9 GHz产生一个陷波特性,有效避免超宽带系统与窄带系统之间的干扰,实现超宽带系统与WLAN和WiMAX系统的协同工作.利用高频结构软件HFSS对设计的天线进行仿真分析,结果表明,在3.1～10.6 GHz频带范围内所设计的超宽带天线的回波损耗小于10 dB,并在5.1～5.9 GHz范围内回波损耗大于10 dB,实现了超宽带系统与IEEE802.11 a(5.1～5.9 GHz)的协同通信.     

毫米波星载多频段多极化共馈天线系统

天线工作频率为18.7,23.8GHz和37.0GHz,采用环加载波纹喇叭使工作带宽达到2倍,新型结构的超宽带正交模耦合器实现双极化信号的提取,微波多工器完成3个频段信号的有效分离. 18.7GHz信号交叉极化电平和副瓣电平分别为-32.6,-21.0dB,23.8GHz信号交叉极化电平和副瓣电平分别为-31.6,-30.0dB,37.0GHz信号交叉极化电平和副瓣电平分别为-25.0,-30.0dB. 仿真结果表明馈源系统适合星载天线设计,馈源结构更加紧凑,实能现对同一目标的多频率复用观测.      

高隔离度的双极化口径耦合微带单元与阵列天线

提出一种新型的双极化微带贴片单元与其阵列设计,该单元采用一对相互垂直的“H”形缝隙作口径耦合馈电,获得了良好的端口隔离度(在工作频带8.8～9.8 GHz内实测值大于42 dB).该结构用于SAR系统天线的子阵设计时,其网络布置较为简单.基于此设计,研制了八单元直线阵列天线,理论仿真和实验相当吻合,不但测得高的端口隔离度(>30dB),而且实测的交叉极化特性很好(<-32.5 dB).     

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…     

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.     

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.