基于广义等效介质激电模型的有限长源频率域一维正演

为研究广义等效介质激电模型(GEMTIP模型)中的极化参数对有限长导线源的频率域响应的影响规律,首先介绍了GEMTIP模型;然后将模型引入有限长导线源频率域测深一维正演中去;进而得到带激电信息的水平电场信号。重点研究了在层状介质条件下不同的极化参数对水平电场影响情况,通过分析发现体积占比对电场值的影响最大,在中高频处异常明显;其次是面积化系数,激电异常在低频处明显;相同极化参数对应的三层地电模型有如下规律:Q型模型的激电异常最大,反映极化层的能力最强,H型模型反映极化层的能力最差,A型和K型则位于两者之间。     

运用对称四极测深研究层状极化介质频谱特征

不考虑电磁感应,用Cole-Cole模型表征极化介质复电阻率,正演计算对称四极装置测深2种典型层状极化介质频谱激电谱曲线和其2个极距的频谱.计算结果表明,时间常数值较大的极化层(如炭层等)所反映的相位曲线,当频率为0.01～1 000 Hz时,随着频率提高,相位负异常递减;时间常数τ值较小(如块状硫化物等)的极化层反映的相位谱与τ值较大的极化层所反映的规律不同;在同样的频率范围内,随着激发频率的提高,相位负异常递增,而后又递减;时间常数τ值较大的极化层的相位频谱特征频率要远远小于τ值较小的极化层的相位频谱特征频率.这些谱特征为区分矿与非矿提供了理论依据.     

含电磁耦合效应的偶极-偶极装置频谱激电响应特征研究

开展含电磁耦合的频谱激电响应特征对实际勘探中的电磁耦合干扰的识别和去除具有实用价值。本文从频谱激电的实际应用出发,推导基于cole-cole模型的水平层状介质接导线AB发射和MN接收的复阻抗计算公式,然后利用快速汉克尔变换进行计算实现含电磁耦合的频谱激电一维正演。通过含对不同频谱激电参数下半空间的纯cole-cole模型和含电磁耦合效应模型的响应特征进行对比分析,结果表明:视电阻率在频率小于10Hz时基本无电磁耦合效应影响,相位在频率小于1Hz时无电磁耦合效应影响,1Hz-105Hz先下降后上升在1000Hz出现极小值。因此在实际应用中应选用10Hz以下频段进行勘探。     

双H型石英音叉陀螺驱动信号频率跟踪算法的研究

为提高双H型石英音叉陀螺驱动信号的稳定性,基于DSP设计了一种数字化闭环控制电路,依据双H型石英音叉陀螺在串联谐振频率点处工作时驱动叉指振动的幅度随频率变化的影响最小,通过相位控制实现了驱动信号频率的跟踪,并利用希尔伯特变换产生了一对正交的参考信号用作相位检测.实验结果表明,双H型石英音叉陀螺工作稳定后,驱动信号频率跟踪算法的相位标准差为4mrad,精度达到0.003 4Hz.     

基于双二次插值的2.5维FCSEM有限元正演模拟

首先给出2.5维频率域可控源电磁的有限元方程,并详细推导基于矩形剖分及双二次插值的有限元方程的刚度矩阵的求解过程;接着重点研究波数的选取并得到一组精度较高的波数选取方案;然后利用本文基于双二次插值的有限元算法对一个均匀半空间模型进行模拟计算,并将计算结果与解析解对比,验证本文算法的正确性;最后对2个二维地电模型进行有限元模拟,分别得到TE及TM模式下的视电阻率及相位等值线断面图,通过对比分析可知模拟结果均能在不同程度上反映出异常体,从而进一步说明本文算法能够对2.5维频率域可控源电磁进行有效地模拟。     

外力对产生螺型位错的影响

基于二维Frenkel-Kontorova模型,通过数值模拟,研究了在外驱动力作用下,交变力的频率和振幅对产生螺型位错的影响.结果表明,交变力的频率越低,振幅越大,越容易产生螺型位错.     

频率域激发极化法的观测系统

本文用系统理论研究了激发极化法的观测过程,从理论和实验两方面论证了时间域激电和频率域激电的等效性及其相互转换性。讨论了频率域激电的几种观测系统;在分析对比的基础上,指出作者等人发明的双频道激电观测系统具有快速、轻便、抗干扰能力强、成本低等优点,特别适合山区和中高阻地区应用。在激发极化观测中,用供电电极向地下送入供电电流,并从测量电极观测电位差(或电位)。因此可将对大地进行激发极化观测抽象为双口系统,系统输入的激励为电流,系统对激励的响应为电位差。按激励方式可分为时间域和频率域。一般说来,可极化大地表现为非线性系统,并可根据其非线性来研究激发极化现象。然而,在通常情况下,它是一个弱的非线性系统。当电极距不大、所用频率较低且频率范围不宽、激励电流密度较小时,可将其看作是线性时不变系统。皮尔通提出的Cole-Cole模型模拟极化效应,实践证明其近似程度是比较好的。这也说明激发极化系统可看作是线性时不变系统。对线性时不变系统,时间域和频率域的测量结果不仅是等效的,而且用拉普拉斯变换可以互相转换。由于激发极化系统是一种最小相移系统,在频率域观测中,其实分量、虚分量、振幅和相位之间并非彼此独立,而是相互依赖,只有一个量是独立的。我们用Cole-Cole模型计算出实分量Re(ω)、虚分量Im(ω)、相位φ(ω)和振幅|V(ω)|随频率的变化,并用转换近似关系式(7)计算出Re(ω),Im(ω),φ和|V(ω)|。从图2看出它们的特征是一致的,彼此等效。另外在实验室用BT—6超低频频率特性测试仪观测了黄铁矿标本和石墨标本的振幅和相位随频率的变化,按式(7)转换成|V(ω)|和φ(ω)。由图3可见尽管实测曲线存在观测误差,|V(ω)|与|V(ω)|,φ(ω)与φ(ω)间基本形态是一致的。频散率P.F.E.与相位曲线形态相似,极值频率也大体相对应。频率域激发极化法的观测方案概括起来可分为变频方案、奇次谐波方案和伪随机信号方案三类(图4示出几种方案的波形和频谱)。这些方案各有优缺点,因而不存在用一种方案完全取代另一种方案。在一般情况下它们之间也是彼此等效的,然而由于它们各自优缺点不同,适应的条件也是有差别的。与变频方案、奇次谐波方案相比,双频道方案具有一些突出优点。例如双频道观测方案中两种频率的频率差可任意选择,而二者的振幅是接近的;这对于在减轻供电功率的条件下,准确地测量视频散率或相对相位差均十分有利。又如采用双频道方案观测时,发送机电流的变化对测量结果的影响也很少,我们曾就电流变化对测量视频散率的影响进行了理论计算和实验,结果表明,在相同情况下,当对变频方案影响为-12％时,对奇次谐波方案影响为-1.06％,对双频道方案的影响仅为0.148％。而且,双频道方案可不须稳流,这对于简化和减轻发送机有利。此外,双频道观测方案可方便地抑制电磁耦合影响。图4表明,对于单纯的方波,电磁耦合影响与激发极化效应都是周期地出现,难于提取它们之间的差别;但是,双频道方案则不然,电磁耦合效应随高频周期地出现,而激发极化则主要随低频周期地出现,因而能够方便地将两种信息分离出来。我国金属矿多产于山区,交通不便,需要轻便快速的普查方案;相比之下,双频道方案较现有的其它方案更优越些。     

基于Dias模型的天然场激发极化法有效参数

为了从天然场源较强的电磁效应中提取有效的激电异常参数,找到能与目标介质物性和电化学过程相关的物理量进行异常评价,通过提出相位峰值偏移距和相对视频散率参数作为一对充要条件用以评价激电异常,同时选用表征频率域激电精度较高且参数丰富的Dias模型进行一维层状模型正演计算,通过分析复电阻率的相位特征验证相位峰值偏移距的有效性和...     

用并矢Green函数的矢量本征函数展开式评价偏心对随钻电磁波电阻率测井响应的影响

采用圆柱坐标系下径向成层介质中磁流源并矢Green函数的矢量本征函数展开式计算电磁波电阻率的测井响应,考察井眼内仪器偏心对测井响应的影响.计算时采用径向成层圆柱形地层模型并假设在每一圆柱层内地层是均匀各向同性的,这样每层介质内的电磁波是对称的柱面波和各阶非对称波的叠加.计算结果表明:仪器偏心的影响随频率的升高而增加;对于电阻性(电导性)钻井液,地层电阻率越低(越高)越需要对仪器偏心的影响进行校正.     

自动幅度控制电路在射频CMOS电感电容振荡器中的应用及原理分析

分析推导了互补金属氧化物半导体(CMOS)电感电容振荡器的电压振荡幅度与相位噪声的关系.采用自动幅度控制电路控制射频CMOS电感电容振荡器,在0.18μm CMOS工艺下进行Candence SpectreRF仿真,在3.4 GHZ时,1MHz频偏处相位噪声最差值采用自动幅度控制电路为-113.3dBc/Hz,不采用自动幅度控制电路为-105.1dBe/Hz.在不同频率下对振荡器相位噪声仿真结果表明,当频率变化从3.16-3.4 GHz时,采用自动幅度控制电路的相位噪声都低于不采用自动幅度控制电路的相位噪声.由此得出通过控制振荡器振动振幅,提高品质因数,可以降低振荡器相位噪声.     

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).     

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.     

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.