优化负反馈放大电路理论研究

以信号电能优化配置的新观点,提出了可用特性不等式组划定的优化负反馈放大电路,得出了负反馈放大电路优化定律,论述了优化负反馈放大电路的理想模型和优化级别,从而建立了在定性和定量上均有突破性进展的优化负反馈放大电路理论。     

基于碳纳米管的CMOS逻辑电路的模拟和优化

基于查表模型,利用SPICE(simulation program with integrated ciruit emphasis)电路模拟软件,首次模拟了互补型碳纳米管(CNT)场效应晶体管组成的反相器,模拟结果和实验结果吻合,实现了碳纳米管场效应晶体管的实际测量数据和半经验查表模型的衔接.利用直流特性分析和瞬态特性分析等仿真手段研究了CNT CMOS反相器的功耗和门延迟特性随工作电压和器件阈值电压变化的关系,并对电路设计和工作状态提出了优化方案.进一步模拟了与非门和或非门,并提出了电路的优化方案.     

RC耦合单管放大电路低频特性的分析

放大电路低频特性是放大器的重要特性参数之一。本文利用h参数低频等效电路，从放大电路的整体出发，把射极旁路电容Ce，以阻抗的形式分别折算到放大电路输入、输出回路中，分析其频率响应特性。     

放大电路的频响分析

研究电路对信号传播的响应，一直是电子电路分析和设计的重点．本文对放大电路的瞬态响应、稳态响应、以及二者之间的关系进行了分析研究，全面详尽地剖析了放大电路的频响特性，为放大电路的分析和设计提供了相应的理论分析．     

基于ADS2005的低噪声放大电路的优化仿真设计

针对功耗和体积均受限的专用小型无线通信系统提升通信距离的要求,以提高接收机灵敏度为研究目的,采用软件仿真ADS2005的方法改进了低噪声放大电路RF2373的设计.在仿真软件下通过建立低噪放RF2373的二端口模型,得出了二端口的S参数特性曲线.采用微带线匹配的方法获得了低噪声放大电路的优化二端口模型,以及匹配后的S参数特性曲线.匹配后的各项S参数较匹配前均有所改善,设计的低噪声放大电路满足射频前端电路的特性要求.给专用测试系统的无线数据传输的硬件设计提供了理论基础.     

用图解法分析直接耦合放大电路

本文讨论了直接耦合放大电路的图解分析法，使各级工作点之间互相牵扯的直接耦合放大电路做进一步定量分析，得以用较直观而又简便的图解法．它的分析方法也和阻容耦合放大器一样，是以器件的特性曲线为基础，用作图的方法在器件特性曲线上分析放大电路的工作情况．它的特点是能直接反映器件的非线性，进而适用于大信号的分析．     

优化催化剂密度改善碳纳米管薄膜纯度与场发射特性

对涂敷有不同浓度催化剂的硅基生长出的碳纳米管薄膜的生长状况和特性进行了研究，并且获得了催化剂的优化浓度，在基底上涂敷氢氧化铁溶胶从而引入催化剂颗粒，用低压化学气相沉积法生长出碳纳米管薄膜，工艺表明，碳纳米管薄膜的生长状况受到催化剂密度的影响，当密度太高时，碳纳米管薄膜的尖端效应不明显，且杂质含量较高；当密度太低时，无法生长出均匀的碳纳米管薄膜，扫描电镜分析和场发射特性测试表明，涂敷有优化浓度的催化剂生长出的碳纳米管薄膜，具有更明显的尖端效应，更高的纯度，阈值电压降到95V，透射电镜观察到的碳纳米管直径为10-100nm。     

栅极无偏置JFET放大电路工作点设计整定方法

根据JFET传输特性曲线分布于两个象限的事实设计了栅极无偏置JFET共源放大电路。讨论了栅极无偏置JFET共源放大电路漏极外接偏置电阻Rd的设计方法，并用实验验证．     

放大电路图解分析法的探讨

图解分析法真实地反映出晶体管的非线性特性，可以直观、全面、形象地分析放大电路的静态工作情况、动态范围及波形失真等，对深入理解放大电路的工作情况非常有帮助。     

回路增益弹性法分析大信号下反馈放大电路

本文引用系统主回路分析的新方法—回路增益弹性法对大信号下反馈放大电路的行为特性进行讨论，并通过分析一个二阶反馈放大电路给出一般分析方法和步骤。     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the