结晶高聚物PVDF的长时间极化弛豫效应

研究了室温附近的PVDF样品的极化弛豫规律。发现极化弛豫效应由电极注入的空间电荷产生,并遵从与铁电陶瓷相似的自由弛豫规律。随刺激条件不同而有多种弛豫机构。根据结晶高聚物与铁电陶瓷空间电荷分布的类似性,上述现象可以得到解释。     

PVDF长时间压电弛豫的研究

研究经拉伸及极化处理的PVDF薄膜在室温附近的压电驰豫效应,发现在施力状态下及撤力后的自由状态下样品释放的电荷均遵守自由驰豫规律,考虑到PVDF与铁电陶瓷空间电荷分布的相似性,以及结晶高聚物的多相性,上述现象可以解释。     

铁电陶瓷中的弛豫效应

铁电陶瓷中的驻极体效应和空间电荷效应可以用冈崎清模型统一解释.理论预言的铁电陶瓷中存在电极化弛豫效应和压电弛豫效应得到实验证实.建立了定量的铁电弛豫理论,其结果与实验符合得很好.     

结晶高聚物PVDF的介电吸收电流及释放

研究了经拉伸及极化处理的PVDF在高温附近的长时间介电吸收电流及其释放电流,刺激电场为10~5至10~6vm~(-1),发现上述二种电流均遵守 It~(1/2)∝e~±(at)~(1/2)的规律,介电吸收电流与样品历史有关,介电释放电流与样品历史无关,它们都是由电极注入空间电荷引起的。     

强发射电流反铁电冷阴极材料的实验研究

采用固态烧结工艺制备了位于反铁电/铁电相界附近的PbLa(Zr,Sn,Ti)O3(PLZST)反铁电陶瓷样品.通过测定样品在快速单脉冲电压激励下的电子发射特性,得到了激励电压对发射电流的影响规律,发射电流随激励电压增加而增加,当激励电压大于1.5 kV时,发射电流趋于饱和.在单脉冲激励下进行电子发射实验,得到如下结果:在激励电压为800 V、抽取电压为0 V的条件下,发射电流密度为1.27 A/cm2;当抽取电压增加到4 kV时,获得了1 700 A/cm2的大发射电流密度.研究结果表明,室温下PLZST的反铁电陶瓷可在较低激励电压下实现电子发射,发射电流密度大,能够工作于4 Pa的低真空环境中.     

强发射电流反铁电冷阴极材料实验研究

采用固态烧结工艺制备了位于反铁电／铁电相界附近的PbLa（Zr，Sn，Ti）O3（PLZST）反铁电陶瓷样品．通过测定样品在快速单脉冲电压激励下的电子发射特性，得到了激励电压对发射电流的影响规律，发射电流随激励电压增加而增加，当激励电压大于1．5kV时，发射电流趋于饱和．在单脉冲激励下进行电子发射实验，得到如下结果：在激励电压为800V、抽取电压为0V的条件下，发射电流密度为1．27A／cm^2；当抽取电压增加到4kV时，获得了1700A／cm^2的大发射电流密度．     

等静压力及偏置电压下锆钛锡酸铅基反铁电体的介电行为

采用固态烧结工艺制备了位于反铁电（AFE）／铁电（FE）相界附近的PbLa（Zr，Sn，Ti）O3（PLZST）反铁电陶瓷样品．通过测定样品的相对介电常数及损耗与各种参量的关系，得到了等静压力及偏置电压对反铁电体铁电／反铁电相变及反铁电／顺电（PE）相变温度影响的规律．研究发现：极化了的PLZST反铁电材料在一定等静压力的作用下，随着偏置电压的增加其峰值相对介电常数增大，相对介电常数最大值对应的温度降低，FE／AFE转变温度上升，AFE／PE转变温度下降；当等静压力为0．1MPa时，单位偏置电压引起的居里点变化率为-1℃／kV，单位偏置电压引起的FE／AFE相变温度变化率为5．2℃／kV，当等静压力为60MPa时，分别为-2．2℃／kV和3℃／kV。     

极化工艺对压电储能Ba0.96Sr0.04TiO3陶瓷铁电性和场致应变的影响机制

通过Pechini溶胶-凝胶法与传统固相烧结工艺分别制备Ba0.96 Sr0.04 TiO3(BST)粉体和陶瓷.BST陶瓷在不同电压和温度的硅油浴中极化处理,随后采用电场20 kV/cm、周期1000 ms的测试条件,对陶瓷的铁电、储能性能和场致应变进行了测试.在极化温度100℃附近,BST陶瓷出现铁电相向反铁电相转...     

打磨引起的残余应力对BaTiO3陶瓷挠曲电响应的影响(英文)

铁电陶瓷中测量得到的大的挠曲电响应可以用来源于应力弛豫的自发极化表面层机理来解释。然而，产生极化表面层的应力来源尚未完全清楚。本工作系统地研究了表面应力对不同粒度砂纸打磨的BaTiO₃陶瓷的微观结构、介电性能和挠曲电响应的影响。与原始样品相比，打磨后的BaTiO₃陶瓷的挠曲电系数由～600μC/m降至200μC/m以下。但经过200℃热处理并且缓慢冷却后，所有样品的挠曲电系数都恢复到～500μC/m。结果表明，打磨在铁电陶瓷的表面层上引入了应力，在一定程度上影响了其挠曲电响应，但打磨引入的应力不是极化表面层形成的主要原因。     

压敏电阻非欧姆特性的研究

本文对压敏电阻的非欧姆特性做了一定分析.Zno压敏陶瓷电阻内可形成晶界偏析和晶界空间电荷区,利用空间电荷限制电流理论可解释压敏电阻器的非欧姆特性.     

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.     

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.     

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.     

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