分析带金属板结构的建筑物内部雷电脉冲 磁场分布的等效电路法

提出了一种计算带有非铁磁性金属平板结构建筑物内部雷电脉冲磁场的等效电路法.首先对结构内的金属平板进行网格分割;然后根据电流趋肤效应,用双指数函数拟合平板内部沿厚度的电流分布;接着通过变换电场积分方程,将金属平板转换成等效电路网络.将平板的电路模型与框架的电路模型相结合,通过解电路方程得到金属平板结构上的电流分布,进而计算框架内的雷电脉冲磁场.该方法的有效性通过和边界元法进行比对得到了验证.最后,对一幢装有金属平板的大楼内部的雷电磁场进行了计算,分析了金属平板对雷电脉冲磁场的屏蔽作用.     

汽车轮胎金属异物探测原理与探测系统设计

以汽车轮胎金属异物探测为目标,讨论金属异物探测原理,以电涡流传感器为基础,通过感应电涡流的变化实现金属异物探测.设计了一种金属异物探测系统,该探测器能伸进汽车轮胎面与翼子板、挡泥板之间的狭小空隙,有效地检测出刺入汽车轮胎的金属异物.探测器的设计使用PIC16F877单片机为核心处理部件,探测采样的感应信号经A/D转换后,采用频域分析法处理.结果表明,该探测器克服了传统的探测器抗干扰能力差的弱点,探测灵敏度和准确性高.     

脉冲涡流检测集总参数模型

针对已有脉冲涡流集总参数模型的不足,建立了具有一般性的脉冲涡流集总参数模型.首先将导体试件中的脉冲涡流场等效为一簇沿深度方向排开的同轴等半径的涡流环;然后建立了涡流随时间和空间分布的偏微分矩阵方程,推导了涡流回线的电阻、自感与互感计算公式;接着阐述了系统矩阵的特征值和特征向量的物理意义;最后使用有限差分法求解了模型实例的矩阵方程,并进行了实验验证.该模型推导、求解简单,适用于任意厚度的被测试件,能准确地模拟瞬态涡流场的扩散过程,也能预知试件厚度变化时线圈感应电压的变化情况.     

感应式热水器磁热耦合分析

根据液体感应加热和金属体感应加热原理的相似性,推导液体感应加热磁场、涡流和温度场分布方程,建立感应式热水器数学模型.根据数学模型,设定磁场和温度场的边界条件、模拟材料随温度变化特性并建立系统供电电路模型,重点利用分步迭代法进行磁热耦合计算.得出加热体的磁场分布、温度场分布、涡流功率密度,以及发生集肤效应区域提供系统主要能量和控制磁力线逸散能提高加热效率的结论.最后,根据仿真模型预测加热效率,提出系统优化设计方案.     

平衡混频式电涡流金属探测器研究

讨论了平衡混频电涡流金属探测器的组成及工作原理，实验表明该金属探测具有灵敏度高，体积小等优点。     

毫米波被动探测空中隐身目标研究

为探测空中涂层隐身目标,建立了地面辐射计对空中目标进行锥形扫描的天线温度对比度计算模型。在目标下方分别为高发射率地面和低发射率水面的情况下,对晴天时平面隐身目标和光洁金属目标的天线温度对比度进行了对比计算。将3 mm波段辐射计系统固定在地面上,目标分别悬挂于水泥地面和水池上方10 m高度处,分别在晴天和阴天时,采用辐射计系统对隐身目标和光洁金属目标进行了探测实验。计算和实验结果说明,涂层隐身目标比同等大小的光洁金属目标的天线温度对比度大,当目标下方地物的发射率较小时,差别更大。在毫米波被动探测下,空中金属目标表面的吸波材料涂层,不仅不能起到隐身效果,反而会更明显地暴露目标。     

铁磁性导电薄板中磁损耗的理论计算

铁磁性导电薄板是实际中应用的铁磁性器件中最常见、最基本的物理模型.本文给出了在交变磁场的作用下的各向同性的铁磁性导电薄板中涡流效应产生的磁损耗的理论计算公式.结果表明减小铁磁性导电薄板的电导率和薄板厚度,是减小铁磁性导电薄板中由涡流效应引起的磁损耗功率的有效方法.     

无源谐振器在电涡流位移传感器中的谐振增强效应

在两只同轴电磁耦合线圈之间插入一只无源谐振线圈,可利用谐振耦合显著提高能量传输效率。为探索这种谐振增强效应在传感器领域的应用可能性,制作了一只与测量电路无任何引线连接的、由电感线圈及电容串联组成的无源LC谐振器,放置于电涡流位移传感器探测线圈与金属目标靶间的测量通道中。实验结果表明:当传感器工作在该谐振器的谐振频率点附近时,有效探测距离和灵敏度会得到显著增强。进一步针对发射-接收式双线圈位移检测系统进行了实验,结果同样证实了无源LC谐振器介入后的谐振增强作用。该结论对于其他带有电感耦合线圈的传感系统同样具有参考价值。     

微通道-电感法检测金属磨粒质量分数的可行性实验研究

为研究液压油中铁磁性金属磨粒质量分数与微通道中螺线管线圈电感变化值之间的关系,设计并制造了微通道-电感式检测芯片与系统。实验测出同一磨粒在不同质量分数时电感传感器的数值,获得电感变化值和铁磁性金属磨粒质量分数之间的关系曲线。实验结果表明,随着液压油中铁磁性金属磨粒质量分数的增加,电感值增大;采用微通道-电感检测方法检测液压油中铁磁性金属磨粒的质量分数切实可行。     

带包覆层铁磁性金属管道局部腐蚀的脉冲涡流检测

为提高脉冲涡流检测技术在检测包覆层下铁磁性金属管道局部腐蚀时的灵敏度,从仿真和实验两个方面对探头设计进行了研究.采用反向联接结构的双线圈作为激励源,达到线圈电流不过大而磁场能够在局部得到聚焦增强的目的.采用有限元仿真比较了单线圈和双线圈激励时磁场及涡流的分布情况和对局部腐蚀型缺陷的检测灵敏度,并进行了系列检测对比实验.仿真与实验结果相一致,表明使用反向联接双线圈激励探头对带包覆层管道局部腐蚀类缺陷进行脉冲涡流检测可以达到远高于单线圈激励检测的灵敏度.本研究可为带包覆层金属管道局部腐蚀的脉冲涡流检测探头设计提供参考.     

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.     

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.     

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.     

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.     

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