植入器件经皮能量传递模型分析

通过电磁场有限元分析软件FEMlab3.3建立了体导电能量传递模型,设计了3种不同形状的电极以优化电极皮肤接触阻抗来提高充电电流传递效率,所采用的Ag电极具有稳定的电极电解质界面,成本低,可重复使用。通过在体外电极上施加不同等级电压以得到最终结果。根据仿真结果,在保证人体安全电流情况下,体导电电流传递效率可达20%以上,能量传递效率在4%~9%之间,不仅远大于无铁芯电磁感应能量传递效率,而且可以进一步实现体内电池体积小型化。     

体导电能量传递二端口网络集总参数的计算

皮肤电极单元是利用体导电向体内植入器件传递能量的通道,其等效电路阻抗参数则是从电路角度分析体导电能量传递系统的基本参数。针对目前尚无确定这些参数的理论计算方法,提出了基于场路耦合的变载法。通过建立皮肤电极单元的场路耦合模型计算电极端口处电压与电流,并运用全相位FFT谱分析提取电量信号的幅值和相位,在此基础之上,应用变载法求出了各种条件下皮肤电极单元等效电路的阻抗参数,并验证了该方法的正确性。计算出的等效电路阻抗参数可用于体导电能量传递的电路分析和系统的优化设计。     

聚焦电流法隧道超前预报电极布置研究

提出了两种聚焦电流电极布置方式（只用屏蔽电极探测的A-M-A1装置和在屏蔽电极中间再加一电极同时供电的A-M-A0-M1-A1装置）进行隧道超前预报探测。通过导电纸实验证明当掌子面不断接近异常体时观测电位不断下降,聚焦电流进行超前预报是可行的;A-M-A0-M1-A1装置比A-M-A1装置效果较好;超前探测距离与异常体电极距有关。     

5052铝合金电阻点焊电极形状对电极寿命的影响

利用ANSYS软件建立了直径分别为6和8 mm的锥台电极和直径16 mm的球电极所对应的5052铝合金电阻点焊过程的有限元模型,分析了在相同的焊接工艺参数下3种类型电极几何形状对5052铝合金电阻点焊的熔核形成过程及其焊接质量和电极自身磨损的影响,并通过连续点焊试验验证了模型的准确性.结果表明:对于锥台电极,在相同的焊接电流条件下,电极端面直径越小,所得到的熔核尺寸越大,点焊接头质量越好;球电极与工件的接触面积过小,将会使得电流集中、温度过高而发生严重的电极烧损.所建模型的模拟结果与试验结果的误差在4%以内,采用直径6 mm的锥台电极进行5052铝合金薄板焊接时,电极寿命比球电极提高了20%.     

多孔电极极化理论——Ⅱ.有欧姆极化的电极稳态的解和导电特征电流

本文得到气体扩散多孔电极在欧姆极化和液相依差极化下的极化状态的解。提出了表征电极导电性能的“导电特征电流”。推导了由电极电流与特征电流的比值推算电极内部过电位分布、电流分布、浓度分布、电极利用率、有效反应深度以及极化曲线偏离度的关系式、简化关系式及关系曲线。     

导电剂对金属氢化物电极性能的影响

研究了不同种类导电剂（镍粉、石墨）及导电剂含量对金属氢化物电极性能的影响，并用交流阻抗法分析了其影响机理。结果表明，以石墨为导电剂的MH电极活化较快，小电流放电容量较高；以镍粉为导电剂的MH电极大电流放电容量较高；两者混合作为导电剂的MH电极综合性能较好。     

考虑多孔电极内气液分布的数学模型

给出了多孔电极内不同气液分布形状的溶液欧姆定律; 在单孔电极模型基础上定义了电化学反应的有效三相分界线长度概念,并给出了对应的计算方法;建立了基于多孔介质气液分布理论的一维电流和过电位数学模型,用数值迭代方法计算了沿电极面法线方向上的电流和过电位分布,分析了气体饱和度分布和有效三相分界线长度对它们的影响。     

交流电热流对导电岛纳米电极介电组装的影响

为了获得导电岛纳米间隙电极系统中纳米颗粒介电组装成的纳米粒子链的形貌规律,在所制备出的导电岛纳米间隙电极系统中进行了纳米颗粒介电组装实验。基于纳米颗粒介电操控理论,建立了导电岛纳米间隙电极组装体系的纳米颗粒介电组装模型,并通过数值仿真方法,对该介电组装模型中的电场分布和介电组装过程中纳米颗粒所受的介电泳力、交流电热流以及两者合作用的电动力学行为进行了分析,探究了交流电热流对导电岛纳米电极介电组装的影响。实验发现:在导电岛纳米间隙电极系统中纳米颗粒的介电泳组装具有两种模式——纳米间隙之间的体组装与电极和导电岛表面上的面组装,并且组装模式的强弱程度受频率的影响,进而造成组装形成的纳米粒子链的分布和形态的不同。仿真结果表明:当频率增大到350kHz时,纳米缝两侧电热流向发生反向;在频率为150kHz且缝宽为500nm时,会在整条纳米缝任意位置(端点处外)出现电热流旋涡,并且电热流旋涡会随着驱动频率的增加而减弱;随纳米缝宽度减小,电热流对纳米粒子介电组装的影响减弱。     

倾斜多针状电极所形成电场的边界元数值计算方法

根据医用倾斜多针状电极系上的电势,利用边界元积分方程建立任意倾斜多针状电极电流密度（单位长度流入生物导电组织中的电流）离散方程,通过求解线性方程组计算了针状电极上的电流密度．由电极电流密度分布实现了生物组织中任意倾斜多针状电极电流所产生电场的数值计算．通过算例对计算速度和计算方法的稳定性进行考察,获得了较快的计算速度和稳定的计算结果．该方法对于解决医学上倾斜多针状电极所形成电场的计算问题具有重要的借鉴意义,对类似问题是一种快速、有效的计算方法．     

焊接电流对不锈钢GTAW三维焊接温度场影响规律的有限元分析

基于有限元软件SYSEWELD,采用双椭球体热源模型,建立了运动电弧作用下的GTAW焊接不锈钢薄板三维瞬态焊接热过程的数值分析模型。模型考虑了材料的热物理性能参数、相变潜热与温度的非线性关系。利用所建模型,定量地预测了焊接电流对三维焊接温度场与熔池形状尺寸的影响,并进行了试验对比。计算所得焊接温度场与熔池形状特征参数随不同焊接电流的变化规律与实际情况基本一致。     

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.