RC文氏桥正弦波振荡电路工作条件分析

在RC文氏桥正弦波振荡电路的研究中,一般文献对RC串并联正反馈选频网络元件参数的选取都有串并联部分电阻相等、电容相等的对称限制条件.本文通过理论分析指出,RC串并联正反馈网络的选频特性,与R、C元件参数的选取并没有特定限制关系,可以有多种选择方式,从而使电路设计具有灵活性.运用Multisim14软件,在RC串并联正反馈选频网络元件参数不对称条件下在对RC桥式振荡电路进行了虚拟仿真实验,给出了Multisim仿真实验方案,仿真了电路从起振到稳幅输出的工作过程,测试了电路的电压放大倍数等技术指标,虚拟仿真实验、理论分析计算两者的结果相一致.     

RLC 正弦交流电路电量的 Multisim 仿真测试

本文基于探索RLC正弦交流电路电量波形的Multisim仿真的目的,运用Multisim10软件对RLC正弦交流电路的特性进行了仿真实验分析,给出了Multisim仿真实验方案,仿真了电路中总电压、电流及各元件电压的相位关系,虚拟仿真实验结果与理论分析计算结果相一致,结论是仿真实验可直观形象地描述电路的工作特性.     

RC正弦波桥式振荡电路仿真分析

通过运用EWB软件对RC正弦波桥式振荡电路进行仿真分析,探讨EWB软件的应用,以加深学生对电路原理和电路元件参数变化的理解。     

基于Multisim2001丙类功率放大器的仿真研究

阐述了Multisim2001的主要功能与特点,并利用Multisim2001对丙类功率放大器电路进行了仿真,讨论了丙类功率放大器的集电极电流、输出电压、输出功率、集电极效率,晶体管高频功率放大器的高频特性.利用Multisim2001可以很方便地改变元件或电路中参数,观察不同条件下电路的工作情况.     

基于Multisim RC振荡电路的仿真分析

文章介绍了一种EDA仿真软件Multisim2001的主要功能及特点,并用该软件对RC桥式正弦波振荡电路的振荡波形、振荡周期、稳幅环节进行分析。     

一组等价蔡氏忆阻混沌电路的设计

通过改变元件参数, 将不同结构的RC正弦波振荡电路等效为LC并联谐振回路, 用具有非线性特性的忆阻器代替蔡氏电路中的蔡氏二极管, 设计4种等价蔡氏忆阻混沌电路, 并在理论上给出等价条件. 仿真实验结果表明, 实验结果与理论分析和数值计算结果一致, 电路调节方便, 鲁棒性更好.     

一组等价蔡氏忆阻混沌电路的设计

通过改变元件参数， 将不同结构的RC正弦波振荡电路等效为LC并联谐振回路， 用具有非线性特性的忆阻器代替蔡氏电路中的蔡氏二极管， 设计4种等价蔡氏忆阻混沌电路， 并在理论上给出等价条件. 仿真实验结果表明， 实验结果与理论分析和数值计算结果一致， 电路调节方便， 鲁棒性更好.     

倍压整流电路的广义忆阻特性

研究旨在证明二倍压整流电路具有广义忆阻特性,为挖掘倍压整流电路的新功能及新应用提供理论依据.首先,根据电路理论求得二倍压整流电路在电压源激励下输入端口伏安关系式以及电路中电容电压的状态方程;其次,由理论分析所得关系式,选取电路元件参数,施加正弦激励电压,由Matlab软件对端口伏安关系进行数值仿真分析;最后,通过Multisim软件进行虚拟实验以及物理实验进行验证.结果表明理论分析符合广义忆阻器数学定义,数值仿真、虚拟实验及硬件实验3者结果基本吻合,验证了输入端口呈现出忆阻器的3个本质特征,从而证实了二倍压整流电路在取适当电路元件参数时具有广义忆阻特性.     

基于Multisim12可调直流稳压电源设计与仿真

通过Multisim12虚拟电子实验平台对可调直流稳压电源进行设计,并利用虚拟仪表测量电路参数、分析电路性能、完善电路设计。经仿真测试,该可调直流稳压电源性能良好、工作可靠,输出电压和电流、稳压系数等重要性能指标均满足电工电路实验对直流电源的需要。运用Multisim12设计电路,有效地提高了设计速度,节省了设计时间,降低了设计成本。     

射极输出器的Multisim仿真分析

通过运用Multisim软件对射板输出器进行虚拟仿真分析,分析研究了射极输出器的直流工作点和交流电压放大倍数、输入、输出电阻等动态性能指标,仿真测试结果与理论分析相一致.这种Multisim虚拟仿真的方法,可以准确、便捷的对射板输出电路进行分析、设计与调试.     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.