首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
应用静电场的叠加原理,给出电介质边界条件的直接证明,并对电介质边界条件的成因作出直观明了的解释。  相似文献   

2.
用边界条件解决静电场中高斯定理应用、分析电介质的束缚电荷分布所遇到的一些问题  相似文献   

3.
用边界条件解决静电场中高斯电场中高斯定理应用,分析电介质的束缚电荷分布所遇到的一些问题。  相似文献   

4.
从宏观各项同性层状压电介质空间轴对称的问题出发,利用状态变量法和0层面的边界条件,得到适用于计算不同状态变量的关系矩阵,以及状态变量表示的多层压电介质在Hankel变换空间中的解.在选择性计算的基础上,对不同的状态变量,分别采用各自的方式修正关系矩阵,有效地避免了无选择性计算所产生的计算结果失真现象,为解决诸如此类的更复杂的问题奠定了理论基础.  相似文献   

5.
以孔边加载下的Stroh广义应力、广义位移表达式为基础,考虑椭圆孔边界精确的电学边界条件,显式给出在任意点处作用广义点载荷时介质中广义应力函数的表达式.当椭圆孔退化成中心裂纹时,给出了导通裂纹端部的广义应力函数.所得结果为介于绝缘边界条件和导通边界条件下更一般的解.进一步推导了压电介质中一本征变形夹杂对椭圆孔边缘广义应力的影响,所得结果对研究铁电畴变区具有实际意义.  相似文献   

6.
从横观各向同性压电介质的梁的弯曲问题出发,利用互易定理和压电弹性力学的通解,对于一般几何构型和承受载荷的梁,获得精确到各阶的恰当的应力和混合边界条件.推广Gregory和Wan的方法,建立一组在边界上存在快速衰减解的边界条件.为了在边界上产生衰减状态,梁缘必须满足这些条件.当应力和混合条件用于梁缘,显示给出弯曲压电梁衰减状态的边界条件,接着衰减的边界条件用于建立梁理论解(内解)的边界条件.另外还通过弹性梁的分析解,来证实获得的边界条件是恰当的.应力条件下的边界条件与梁理论传统的边界条件一致,重要的是,两组混合条件下的边界条件是首次获得的。  相似文献   

7.
采用模式匹配法对填充电介质的圆形槽波导进行了分析.根据满足边界条件的一系列电磁场方程,推导出填充电介质的圆形槽波导的特征方程.在改变相应的一些条件后,该特征方程分别被简化为圆形槽波导的特征方程和圆波导的特征方程.在特征方程的基础上,计算出几种模式的ω-β曲线,得到在加载不同介质后模式截止频率的变化:随着介电常数的变大,模式截止频率有变小的趋势.这些结论为今后研究加载介质的圆形槽波导的应用奠定了一定的理论基础.  相似文献   

8.
利用双重Fourier级数展开和Galerkin方法获得单向轴压和简支边界条件下压电矩形薄板后屈曲问题的解析解.发现几何参数对屈曲路径的影响与各向同性板类似,后屈曲荷载与压电-电介质综合参数有线性关系,后屈曲路径中存在材料共振现象。最后分析材料参数和几何参数对后屈曲路径的影响。  相似文献   

9.
利用电容器的并联、串联以及能量的方法,计算了充有线性各向异性电介质和对数各向异性电介质时圆柱形电容器的电容,并比较了两种电介质对电容的影响.  相似文献   

10.
电介质材料在物理学的研究中具有非常重要的地位.文章由外电场对电介质作功出发分别推导了电介质所满足的热力学基本方程和Maxwell微分关系,并且由此出发导出了在绝热条件下电介质温度随电场强度变化的规律、介电常数的温度系数变化的规律、等温电致伸缩效应和压电效应的表达式.通过分析可以得出结论,对于介电常数的温度系数(TKE)小于零的电介质,在绝热条件下减小外电场时,电介质的温度将降低.因此利用这个效应可以使电介质通过绝热去电获得致冷效应.  相似文献   

11.
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.  相似文献   

12.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
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。  相似文献   

14.
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  相似文献   

15.
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  相似文献   

16.
17.
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.  相似文献   

18.
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).  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号