电流模式CCⅡ正弦波振荡器的实现

论述由带通滤波器产生正弦波振荡器的一般原理,应用此方法成功地设计了电流模式ＣＣⅡ正弦波振荡器,并对电路进行了Ｐｓｐｉｃｅ仿真。     

滤波器CAD中的自动设计方法

根据网络理论，提出了一种ＬＣ梯形滤波器ＣＡＤ中实现自动设计的方法，滤波器的拓扑结构由计算机根据给定的损耗极点自动确定，所设计的梯形网络的元件均为正值，电感数目最少，且具有较低的元件参数分布。     

一种新的单CCⅡ-实现二阶电流模式滤波器

提出了用单ＣＣⅡ－实现二阶电流模式滤波器的新电路,仅用少量元件,即能实现二阶低通、带通滤波函数。电路用Ｐｓｐｉｃｅ程序进行了仿真。该电路具有电路简单、集成方便,无源灵敏度低等优点。     

全集成MOSFET—C精确连续时间滤波器平衡结构［CCⅡ±］实现及仿真

以全集成ＭＯＳＦＥＴ电流传输器［ＣＣⅡ±］为基础提出了一种积分电路平衡结构，并对其消除非线性因素进行了理论分析。同时提出了相应的基本电路元件的有源ＲＣ双Ｔ滤波器平衡模式。利用ＳＰＩＣＥ（Ⅱ）通用模拟电路程序，对以［ＣＣⅡ±］为基础的一个全集成ＭＯＳＦＥＴ－Ｃ平衡结构６阶低通切比雪夫滤波器输出电压幅频特性和相频特性进行了仿真分析，得到了实用的结论。     

全集成MOSFET－C精确连续时间滤波器平衡结构［CCⅡ±］实现及仿真

以全集成ＭＯＳＦＥＴ电流传输器［ＣＣⅡ±］为基础提出了一种积分电路平衡结构，并对其消除非线性因素进行了理论分析，同时提出了相应的基本电路元件的有源ＲＣ双Ｔ滤波器平衡模式。利用ＳＰＩＣＥ（Ⅱ）通用模拟电路程序，对以［ＣＣⅡ±］为基础的一个全集成ＭＯＳＦＥＴ－Ｃ平衡结构６阶低通切比雪夫滤波器输出电压幅频特性和相频特性进行了仿真分析，得到了实用的结论。     

一种新型模拟电感

在有源滤波器的设计中经常采用通用阻抗变换器（ＧＩＣ）模拟接地电感来实现有源滤波器,然而由于所采用的运放较多,存在消耗功率大和噪声问题,此外元件变化引起滤波器特性的变化大,其稳定性不如ＬＣ滤波器,由此提出了一种新型模拟电感电路。它只由一个运放和电阻电容组成,由这种新型模拟电感代替无源ＬＣ滤波器中的电感Ｌ组成亚音频有源高通滤波器,具有与无源ＬＣ滤波器相同的低灵敏度,并且电路简单经济、减少功率消耗和噪声     

高频连续时间OTA—C FDNR滤波器

本文提出了一种模拟无源梯形ＬＣ电路的高阶ＯＴＡ－Ｃ ＦＤＮＲ滤波器，该滤波器具有低的灵敏度和电调谐特性。文中给出了ＯＴＡ－Ｃ频变负阻器元件特性实验结果和七阶椭圆通ＯＴＡ－Ｃ ＦＤＮＲ滤波器计算机仿真结果。     

一种单CCⅡ型多功能二阶滤波电路

提出仅使用一个ＣＣⅡ器件和７ 个无源元件的滤波器电路, 适当改变电路中无源元件的性质（电阻性或电容性）,可以实现４ 种二阶滤波功能：高通、低通、带通和带阻滤波。由于把Ｙ 端子做为输入端,所以电路具有很高的输入阻抗。以带阻滤波器为例,说明了电路的设计方法,给出了计算机仿真实验结果。     

基于多输出端差动差分电流传送器的模拟电感

为在电路中消除无源电感器，以利于实现电路全集成，提出了一种基于多输出端差动差分电流传送器(MDDCC)的模拟电感电路，并用其和差动差分电流传送器(DDCC)实现的模拟电感构成了连续时间高通滤波器。用PSPICE仿真分析比较了两种模拟电感构成的高通滤波器的特性，仿真结果表明，提出的电路方案在组成高通滤波器时幅频特性优于DDCC。     

模拟电容与电感及其仿真分析

模拟电容与模拟电感在集成电路中得到了广泛的应用.本文引入模拟电容与模拟电感模型,对两模型电路作了详细的时频分析和EWB(Electronics Workbench)软件仿真分析.以五阶Butterworth滤波器电路为例,通过对滤波器电路及其仿真电感替换电路的仿真对比分析,进一步验证了仿真电感模型的电感特性.     

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).     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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