求解RLC谐振电路的一种简便算法

分析讨论了串联谐振和并联谐振的谐振频率,并给出了谐振时电阻、电感、电容元件上的电流和电压的大小,从谐振时电路呈纯电阻特性入手,对RLC谐振电路进行了理论分析,从而找到了一种求解谐振电路的简便方法。     

用计算机研究RLC并串联电路的方法

在无线电技术中广泛地利用谐振电路来选频,各广播电台以不同频率的电磁波向空间发射自己的讯号,调节收音机中谐振电路的可变电容,可将不同频率的各个电台分别接收,当电容C,电感L,电阻R三类元件同时出现一个电路中时,就会发生一种新现象-谐振,这谐振电路是实际中有着重要的作用,谐振电路主要有串联谐振和并联谐振两种,我们讨论以串联谐振电路为主。后面一点讨论并联谐振RLC电路、本篇利用计算机研究求出RLC串联与并联电路谐振状态的品质因数Q的值．     

应用RLC串联选频电路验证方波付里叶分解

实验应用RLC串联选频电路对方波频谱进行分析，分别测量了方波分解的1、3、5倍频正弦波，通过对上述频率谐振电路中电感的损耗电阻测量，计算修正了1、3、5次谐波的振幅，从实验上验证了方波的付里叶分解。     

参变数谐振电路

Ⅰ 问题的由来 在一个串朕谐振电路中(图1.а)电容器上高频电压的振幅,随电容值的大小而异如图1.б所示,此即所谓谐振曲线。电荷振幅的变化,亦与此图极为接近。去谐式高速形变用子记录仪(1)的原理即以谐振电路为基础。测力计构成高频谐振电路中的电容,当所加压力变化时,电容器二极板间的距离随之而变,于是电容器上的电压即能反     

一种新型的可配置传输型微带负群时延电路

提出了一种基于有耗微带耦合谐振单元的传输型负群时延电路,该电路利用电阻加载的方式实现负群时延值的灵活调节.微带耦合谐振单元电路中采用了开路扇形线结构,有效减小了电路尺寸.基于有耗耦合线谐振单元的等效网络模型,分析了加载电阻及耦合系数对信号传输及负群时延特性的影响,并对整体微带电路进行了三维电磁仿真分析.设计加工了一款两级传输型负群时延电路实验样品,在耦合谐振器特定位置分别加载100~300Ω范围内不同阻值电阻的状态下,对该电路的群时延特性进行了测试.结果表明:在中心频率1.79 GHz附近,该电路可配置获得-2~-12 ns的负群时延值,其最大信号衰减在6~10 d B范围内.这种新型的负群时延电路具有结构紧凑、信号衰减小、负群时延值可灵活配置等优点.     

电磁阻尼耦合悬架的内共振参数匹配分析

为了解决电磁阻尼耦合悬架因非线性振动机理复杂而存在机电耦合系数匹配困难,制约其在汽车领域中推广应用的问题,建立电磁悬架机电耦合动力学模型,推导悬架与电磁电路动力学微分方程,应用多尺度法,得到耦合系统中悬架与电路系统固有频率之比为1∶3时的内共振幅频方程和内共振一次近似解。结果表明:在调节电阻值接近线圈固有电阻的前提下,保持其他参数不变,分别改变线圈固有电感、电路电压以及外界激励幅值、频率的数值,会对悬架及电量的幅频响应曲线峰值产生不同影响;悬架的幅频响应曲线峰值随着线圈固有电感和电路电压的增大而减小,随着外界激励幅值与频率的减小而减小;电量的幅频响应曲线峰值随着外界激励幅值与频率的增大而增大,随着电路电压的减小而增大。     

非线性电阻电感型RLC串联电路主共振分析

为了研究非线性电阻电感型RLC串联电路的非线性振动，应用拉格朗日一麦克斯韦方程建立受简谐激励的具有电阻和电感非线性RLC电路的数学模型．根据非线性振动的多尺度法，得到系统满足主共振条件的一次近似解以及对应的定常解．对其进行数值计算，分析系统参数对响应曲线的影响．结果表明：增大极板面积，响应曲线的振幅和共振区变大；增大极板间距、电感非线性系数和电阻，响应曲线的振幅和共振区变小．非线性电感和电阻可以抑制电量的振动．系统的固有频率随极板间距增大而增大，随极板面积和电感线性系数的增大而减小．     

Multisim和Excel在谐振电路实训教学中的应用

在分析串联电路谐振特性时由于测试仪器的限制,导致在传统实训教学中,难以实时监测电路中电感和电容的电压响应随激励频率变化的动态过程。而利用Multisim可以实现对串联电路谐振特性的仿真测试,并将测试结果用Excel图表功能绘制出理想的谐振曲线,从而准确直观地揭示出串联电路选频特性的实质,对传统实训教学起到很好的补益作用。     

用于多导体传输参数提取的等效电流密度法

针对电信号的有效传输受外界环境引起自身参数变化的问题,提出了一种基于有限元方法求取传输参数的等效电流密度法.通过对实验中电路参数法的研究,建立了传输电缆中的多根铜芯相互作用模型.分析了导体间涡流作用的形式,求取此作用产生的感应电压和电流密度重新分布参数,由此推导出电阻和电感传榆参数求解公式,由有限元方法实现了参数提取.仿真结果表明:这种方法能够实现多导体模型电阻和电感参数的有效提取;当信号频率升高时,交流电阻及功耗有所增加;电阻和电感参数均有相应的频变特性,即在特定频段内呈线性变化.     

基于非定常机电转换系数的超磁致伸缩换能器输出振幅模型

为实现对超磁致伸缩超声换能器输出振幅的准确预测,由换能器的等效电路推导得到输出振幅模型,并通过阻抗分析辨识出模型中的等效参数。为提高模型的准确性,研究了激励信号的频率和电压幅值对机电转换系数的影响。通过实验建立机电转换系数与激励频率的关系曲线,插值得到不同频率激励下换能器的机电转换系数,由振幅模型得到换能器输出振幅与激励电流幅值的关系曲线。结果表明:基于阻抗分析结果建立的振幅模型能够较准确地预测换能器在谐振状态下的输出振幅,验证了振幅模型的正确性。基于插值法得到的振幅-电流幅值曲线与实验结果一致,验证了所建立的机电转换系数与激励频率之间关系的正确性,提高了振幅模型在不同频率下的准确性。     

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.     

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.     

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.     

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.     

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.