电容层析成像系统三维电场分析及阵列电极优化

通过电磁场有限元软件ANSYS仿真,构建电容层析成像(ECT)系统敏感阵列电极三维模型,分析ECT敏感场的"软场"效应,推导计算灵敏度矩阵,并分析敏感阵列电极结构参数对ECT电场灵敏度的影响,进而优化阵列电极结构.实验结果表明,利用优化的阵列电极可获得较均匀的敏感场分布及较高的检测灵敏度,并重构出较满意的图像.     

数字化ECT成像系统

基于电容敏感原理设计的数字化电容层析成像系统,利用有限元法,分析了阵列电极结构对敏感场分布的影响,通过优化设计和仿真试验,改善了敏感场分布的均匀性;构建了以DSP为核心、FPGA协同工作的12电极的数字化ECT系统,提出了由离线预迭代和在线一步成像所构成的新的图像重建算法——预迭代法,其成像速度及精度均明显提高．     

基于均匀设计和最小二乘支持向量机的电容层析成像传感器优化设计

提出一种采用均匀设计与最小二乘支持向量机相结合的电容层析成像传感器结构参数优化方法．该方法以敏感场均匀度为设计目标，采用均匀设计安排试验，试验因素包括ECT传感器的4个重要参数即：极板张角，绝缘管道材料相对介电常数，管道壁厚，以及屏蔽罩与电容极板间的间距．运用最小二乘支持向量机对试验结果进行回归分析，并用因素轮换法进行寻优计算，从而得出优化的传感器结构参数．结果表明：经过优化的电容成像系统具有较好的成像效果．该方法试验次数少，具有较强的实用性．     

ERT／ECT双模态敏感阵列电极优化设计

在过程层析成像系统中,传感器电极阵列的设计直接影响到整个系统．为了使系统获得更高的图像分辨率,通过电磁场有限元仿真软件COMSOL分析,构建ERT／ECT双模态敏感阵列电极三维模型．基于敏感场分布的均匀性、相关系数及空间分辨率等优化指标,进行了ERT／ECT双模态敏感阵列电极优化设计．实验表明,三维ERT电极选圆形电极,且其电极直径为0．3s;而三维ECT阵列电极选矩形电极,其宽为0．65s,高为1．8R（s为2πR／16;R为管道半径）为佳．优化设计的敏感阵列电极可获得较均匀的灵敏场分布及较高图像质量．     

基于叉指结构的平面分形电容研究

以基于叉指结构的平面分形电容为研究对象,电容由激光刻蚀法制得,在测得其S参数后,利用ADS仿真工具进行了一阶等效电路参数提取及分析.结果表明,随着共面叉指电极间距的相对减小,电极间的耦合增大,相应的寄生电感也增大;而分形设计可以在保证电极间距不变的情况下,改善电容的工作稳定性.最后制得的分形平面电容的电容值在1~7 pF之间,电容稳定工作频率可达2.5 GHz以上,显示了较好的可调性和稳定性.     

宽调谐范围低相位噪声的小面积VCO设计与实现

为了解决压控振荡器的调谐范围、相位噪声、功耗和芯片面积等指标难以多重优化的问题,本文基于TSMC 40 nm CMOS工艺,通过设计改进型开关电容阵列、高Q值LC谐振电路和大滤波电容等结构,实现了一种宽调谐范围低相位噪声的小面积压控振荡器.采用NMOS型负阻结构,以适应于0.9 V的低电源电压电路.将改进型开关电容阵列...     

电容阵列开关时序优化在A/D转换器中的应用

欲提高逐次逼近式A／D转换器的精度，常受到内部DAC（Digital-to-Analog Converter）结构参数误差等因素的制约，同时A／D转换器的低功耗问题亦受到关注．为减小电荷分布式DAC中电容离散引入的积累梯度误差，改善输出积分线性度（INL，integral nonlinearity），引入INL bounded算法对实际工艺条件下的DAC电容阵列的导通时序进行了优化．通过引入预增益级和Latch级，改进了内部比较器的结构，降低了静态功耗，提高了转换精度和工艺的可靠性．仿真结果表明，设计ADC的分辨率可达14bit，其1NL提高2倍以上，功耗8．25mW．该设计可利用0．6μm2P2M标准的CMOS工艺实现．     

电容层析成像多电极激励方法分析

电容层析成像中的图像重建是一个不适定求解问题，电容的微测量误差将会引起较大的图像重建误差，因此提高互电容测量精度是保证图像重建质量的关键．分析了电容层析成像中电容测量原理，在此基础上，将多电极激励方式运用于电容层析成像中．经仿真实验表明：在电容层析成像的电容检测中，与目前普遍采用的单电极激励方式相比，采用多电极激励方式同样可以提高检测电极的电荷量32％～180％，从而有利于提高对互电容的检测精度。     

权电容DAC状态转换速度估计方法

为提高权电容阵列DAC的性能,本文通过建立权电容阵列DAC的理想模型和状态转换模型,求解出零状态输出和非零状态输出,证明了权电容阵列DAC输出仅包含系统的零状态响应,而与前次输入无关.根据权电容阵列DAC的频率响应特性和时域响应函数,得到一种电容阵列DAC转换速度的估计方法,并建立了支路时间常数与转换开关导通电阻之间的限制关系.通过仿真分析验证了权电容阵列DAC转换速度的估计方法,为权电容阵列DAC的设计和应用提供了理论依据.     

电容式两相流相浓度传感器的仿真及优化

采用有限元法，对电容式两相流相浓度传感器引入计算机辅助设计。建立电容传感器理论模型，对两相流各种典型流型进行仿真．分析了传感器各结构参数对测量的影响，为传感器的优化设计提供了依据。研究了一种均匀旋转电容敏感场的多电极传感器，有效地减少了两相流流型变化和不同的相分布对测量的影响，使得传感器性能有明显的改善。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

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。     

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.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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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