Delta Sigma调制器非理想因素建模

提出并构建了开关电容积分器Delta Sigma调制器非理想因素行为级模型,该模型基于Matlab中的Simulink工具,包含开关非线性、时钟抖动、量化器非线件和积分器非线性等调制器非理想囚素,能为电路模块的设计提供精确的设计指标.重点研究并实现一种运放非线性直流增益模型,仿真结果表明它能更有效反映奇次谐波失真.同时综合考虑调制器其他非理想因素,例如采样噪声、开关非线性电阻以及运放参数(色化噪声.增益带宽,摆率,饱和电压),仿真得到其对调制器性能的影响.     

MASH21 Sigma-Delta调制器的自顶向下设计

提出MASH21调制器的自顶向下设计方法。在系统级, 通过系数缩放对积分器的输出进行限制; 在电路级, 通过积分器的瞬态建模分析运放非理想因素对调制器的影响, 并得到SNR和面积功耗最优的设计区域。通过一个数字音频MASH21调制器的设计对此方法进行了验证。该调制器基于TSMC18MMRF工艺实现, 在1.8 V的单电压下工作, 测试显示调制器的SNDR达到91 dB。     

基于SIMULINK的气隙局部放电仿真技术研究

为了解决目前国内外局部放电仿真方法难以计算气隙局部放电暂态过程的问题,利用MATLAB(SIMULINK)的公共模块库和电力系统专业模块库,根据单气隙局部放电仿真物理模型,构造了气隙局部放电仿真计算的电路.研究了气隙放电过程的电压控制方法、分段时间控制方法、线性时间控制方法以及非线性时间控制方法,从而实现了多种控制方式下单气隙局部放电暂态过程的计算机仿真.得到的工频周期内的仿真波形和纳秒级单次放电仿真波形均与实际测量波形比较接近,证明利用SIMULINK可以进行气隙局部放电过程的仿真.该方法具有建模方便、运算速度快等优点,是一种十分有效的方法.     

一种新型级联ΣΔ调制器系统结构

针对传统高阶级联ΣΔ调制器结构电路复杂和对运算放大器的增益和线性度要求较高的缺点,提出了一种新型的2-3两级5阶多位量化器级联ΣΔ调制器系统结构.该结构的第1级采用2阶多位量化器的低失真ΣΔ调制器结构,减小了运算放大器的非线性有限增益对调制器性能的影响.第2级采用信号传递函数等于单位增益的单环3阶ΣΔ调制器,而不是传统级联结构中1阶或2阶ΣΔ调制器,降低了电路的复杂程度.系统仿真结果表明：在最大增益为70 dB的非线性运算放大器增益、±0.2%的随机数模转换误差的非理想条件下,该调制器的最大信号噪声失真比能够达到95 dB.     

非线性油气悬架系统平顺性仿真与参数优化设计

基于油气悬架台架实验,建立工程自卸车八自由度数学模型,该模型包含刚度五次方非线性和阻尼立方非线性.在此基础上利用SIMULINK建立仿真模型,并用实验验证仿真模型的正确性.通过对油气悬架参数的灵敏度分析,确定优化变量,然后以行驶平顺性为优化目标,建立油气悬架参数优化模型,利用SIMULINK、遗传算法对油气悬架参数进行联合优化设计,得到油气悬架理想的非线性刚度和阻尼特性曲线.仿真分析与实验结果表明:油气悬架的减振特性需要进一步优化设计.优化后,各车速下座椅的加权加速度均方根值分别降低了约17.3％,18.8％,25.8％,油气悬架的减振性能和整车行驶平顺性得到明显改善.     

一种新型级联∑△调制器系统结构

针对传统高阶级联∑△调制器结构电路复杂和对运算放大器的增益和线性度要求较高的缺点,提出了一种新型的2-3两级5阶多位量化器级联EA调制器系统结构.该结构的第1级采用2阶多位量化器的低失真∑△调制器结构,减小了运算放大器的非线性有限增益对调制器性能的影响.第2级采用信号传递函数等于单位增益的单环3阶∑△调制器,而不是传统级联结构中1阶或2阶∑△调制器,降低了电路的复杂程度.系统仿真结果表明:在最大增益为70 dB的非线性运算放大器增益、±0.2%的随机数模转换误差的非理想条件下,该调制器的最大信号噪声失真比能够达到95 dB.     

不确定Sigma-Delta调制器的鲁棒滤波

研究级联Sigma-Delta调制器在非理想性电路中的鲁棒校正滤波器设计问题.基于MARKOV区间算法和线性区间系统的等价描述,将扰动抑制问题转化为增广系统的鲁棒稳定问题.给出以线性矩阵不等式描述的鲁棒滤波器存在的充分条件,该条件保证所设计的校正滤波器能有效抑制电路不确定性对调制器性能的影响.仿真结果表明,与传统校正滤波器相比,该调制器获得了更好的信号噪声比.方案降低了电路实现过程中器件精确度的要求,从而达到低应用成本的目的.     

高阶Σ-Δ调制器的滑模电路设计方法

提出了一种新的高阶Σ-Δ调制器滑模电路设计方法.首先,证明了滑模控制系统的Σ-Δ调制编码功能,进而推出了Σ-Δ调制器传输函数形式的稳定性判据;然后,结合判据提出了一种稳定的巴特沃斯极点、零点优化的传输函数设计算法;最后,利用建立参数方程及求解、参数仿真调整,设计了Σ-Δ调制器的环路滤波器级联结构的电路,并通过一个设计实例及仿真,验证了所提方法的可行性.     

一种行为级的仿真方法及Sigma-Delta模数转换器的最优化设计

提出了一种行为级仿真方法,可以用于Sigma-Delta模数转换器系统级和行为级设计。与传统的行为级设计方法相比,该方法拥有更高的速度,更加易于使用,并且对于行为级设计来说有更高的效率。采用这种仿真方法,能详细分析模拟电路单元的非理想特性如积分器、比较器、运算放大器等,有助于实现高性能设计。为了验证该设计方法的有效性,设计了一个二阶Sigma-Delta模数转换器,并采用0.13μm混合信号CMOS工艺进行了流片。测试结果显示,调制器可以实现77.2dB的最高信噪比,相当于12.5位量化精度,而功耗仅为5.9mW(包括抽取滤波器为6.2mW)。     

过采样∑Δ调制器结构参数设计自动化

采用基于最小偏差逼近多项式和递推法求解待定系数方程的方法 ,开发了一套内插式过采样 ∑ Δ调制器设计自动化软件 ,动态调整调制器的结构参数 ,使 ∑ Δ调制器的性能得到优化 .给出了一个具体的内插式 ∑ Δ调制器的设计实例 ;为了解设计的性能 ,给出了该 ∑Δ调制器的谱特性 .实验结果证明 ,使用该自动化软件 ,可以进行采用过采样技术的数 -模转换器中内插式 ∑ Δ调制器的参数设计 .     

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.     

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.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-