用谐振腔微扰法测量太阳能电池片的介电常数和介电损耗角正切

实验利用近代物理微波技术实验仪器,采用谐振腔微扰法,测量太阳能电池片放入谐振腔前后的频率,应用电磁场理论,能计算得到介电常数的虚部ε″和ε′实部,进而求出太阳能电池片的介电常数ε=ε′-iε″和介电损耗角正切tgδε。     

碳纳米管的微波介电特性

在2~18GHz频率范围内研究了多壁碳纳米管的微波介电特性.结果表明:在这一范围内其复介电常量和介电损耗较大,具有较强的宽频带微波吸收能力。多壁碳纳米管与石蜡复合体的复介电常量的实部ε′在测量范围内随频率增加而减小,具有明显的频响特性;ε′和介电损耗角正切tanδ随碳纳米管含量的增加而增大,可以通过含量进行调节选用。ε′与碳纳米管体积分数v之间符合二次函数关系(ε′=Av2 Bv C),电矩转向的弛豫型极化是碳纳米管吸收损耗微波的主要原因。     

二茂铁有机磁性材料的应用

与无机铁氧体比较,以二茂铁为原料,按专利献合成的二茂铁有机磁体在广泛的温度范围内磁性能十分稳定,在10—1800MHz的高频、微波下,磁导率(μ′)和磁损耗(μ″)基本不随使用频率而变化,应用研究表明,它是一类新型的软磁材料,适于制作许多高频和微波电子器件。     

间苯二甲酰二茂铁二乙酰腙金属(Cu,Co,Ni)配位聚合物的高频介电性能

报道了用ＵＶ、ＩＲ及元素分析探讨了间苯二甲酰二茂铁二乙酰腙金属（Ｃｕ,Ｃｏ,Ｎｉ）配位聚合物的可能结构,以及在１０－１０００ＭＨｚ广泛频段下３种配位聚合物的介电常数－频率（ε′－ｆ）,介电损耗的正切－频率（ｔｕδ－ｆ）以及介电常数－温度（ε′－Ｔ）的关系。     

无宏观缺陷水泥基复合材料的介电性能

在 1 0 2 ～ 1 0 7Hz频率范围内测定了酚醛树脂 -高铝水泥基无宏观缺陷 (MDF)材料的介电常数和介电损耗随材料组成及环境湿度的变化曲线 .结果表明 ,MDF材料的介电常数和损耗皆与测试频率有关 ,介电损耗由载流子屏蔽跳跃引起 .当材料内酚醛树脂的数量增加时 ,介电常数下降而损耗略有上升 ,添加硅灰能显著改善材料介电性能 ;在低相对湿度下 ,湿度对介电性能影响不大 ,在高相对湿度下 ,介电常数和损耗都有较大的增加     

直接冷却超导磁储能磁体加载实验与热分析

阐述了35 kJ高温超导磁储能系统及其实验装置,通过对直接传导冷却超导磁储能磁体进行电流加载实验,对磁体进行了动态热分析.研究表明:在变流器对超导磁储能磁体充放磁储能过程中,磁滞损耗是功率损耗的主要部分,对磁体温升影响最大;减小变流器直流侧频率有利于抑制磁体温升.基于热稳定性分析了导冷结构的优化因素,指出直接冷却导冷结构应强化关键部位(磁体上部)的传热,以减小磁体轴向温差.     

煤和浸提剂的介电性质与煤炭微波脱硫的关系

一、前言煤炭微波脱硫是近年来国外发展较快的一种煤炭脱流方法,它不仅能有效地脱除煤中的无机硫,对有机硫也有一定作用。该法依据煤中各组分在一定频率的微波场中介电性质的差异,选择性吸收微波能,发生脱硫反应。微波能与介质之间的耦合度用微波能在单位体积介质中功率损耗表示为: P/V=πfε。E~2ε″_r (1)式中:π、自由空间的介电常数,ε。为常数,频率f、场强E对一定设备、在一定频率下为常数,介质的介电损耗ε″_r号取决于介质的性质。可见,介质与微波能之间的相互作用与其介电性质密切相关。本文测量了煤与浸提剂的介电性质,并结合微波脱硫试验,考查了两者之间的一些规律性。     

微波参数对微波烧结过程中电场分布的影响（英文）

用电磁仿真软件HFSS对加载了圆柱形样品烧结腔的电场分布进行了研究。设定不同的介电常数εr和介质损耗角正切值tgδ以便获得不同的电场分布云图。分析和讨论了相对介电常数和介电损耗角对烧结腔和样品的电场分布影响。研究结果表明,不同的相对介电常数对电场分布存在显著的影响,但介电损耗对其影响不大。     

片状石墨表面化学镀Ni-Co-P合金的制备及其吸波性能

采用化学镀工艺在片状石墨表面镀覆一层Ni-Co-P合金,对包覆后的样品进行了扫描电子显微观察(SEM)、X射线衍射分析、磁性能及吸波性能表征。结果表明,石墨表面沉积的镀层完整致密,以非晶态为主,且得到的镀Ni-Co-P石墨具有一定的磁性。矢量网络分析仪测试了样品在0.1～14 GHz频率范围内的复介电常数(ε=ε’-jε″)和复磁导率(μ=μ’-jμ″),用吸收屏理论公式计算了反射率损耗(R.L),得到当匹配厚度为5 mm时,镀Ni-Co-P石墨的最大吸收峰值约为-9.1 dB,超过-5 dB的频宽达4.2 GHz,是一种比较理想的新型复合吸波材料。     

镍铁氧体纳米晶的制备及电磁性能研究

通过高分子凝胶法制备了尖晶石型镍铁氧体(NiFe2O4)纳米晶.采用FT-IR,X射线,TEM和波导等方法对产物以及产物的电磁性能进行了表征.结果表明,干凝胶为无定型状态,当煅烧温度高于400℃时,形成纯相的尖晶石型纳米晶.煅烧温度为400,600和800℃时,由透射电镜照片可知粉体平均粒径分别约为8,25和40 nm,红外光谱显示金属-氧离子(M—O)键的特征吸收峰出现了红移,该峰红移23 cm-1;纳米晶在8~12 GHz的测试频率范围内具有介电损耗与磁损耗,随着热处理温度的升高,镍铁氧体纳米晶的介电损耗和磁损耗明显增大.     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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