沿面放电相互作用形成的超四边气体放电斑图

在介质阻挡放电中首次发现了由沿面放电相互排斥而形成的超四边形斑图,该斑图是由亮点、暗点、亮线组成的.用普通相机对该斑图进行短曝光拍摄,发现暗点是由四个小点组成的.用高速录像机对斑图进行曝光时间为20μs的拍摄,发现暗点是由沿面放电的相互排斥形成的,亮点是体放电.用逐渐增加高速录相机曝光时间的方法对斑图进行拍摄,结果发现,亮线是沿面放电在长时间下叠加而成的.对斑图的亮暗点的光强作了对比,发现亮点和暗点的光强之比约为10.用光电倍增管对斑图进行光信号的测量发现亮点在每半周期内进行多次放电,其中仅有一次在电压的下降沿,也反映出暗点和亮线的放电模式与亮点不一样.最后通过光谱的测量表明:亮点与亮线和暗点有不同的等离子体参数,证实亮点和暗点是不同的放电模式.最后采用壁电荷理论对斑图的形成进行了解释.     

介质阻挡放电中新型超四边形斑图的研究

在高氩气含量的混合气体放电中,首次观察到大小点不完全插空的新型超四边形斑图.采用高速相机(ICCD)和光电倍增管(PMT),对此斑图的时空动力学进行了研究.结果表明,斑图由三套不同的子结构相互嵌套构成,每半个电压周期内子结构的放电顺序为:小点-大点晕-大点中心点.并且在每半个电压周期的下降沿,中心点的放电对应着两个明显的电流脉冲,放电时刻具有选择性.经分析可知:由于中心点在下降沿放电的时刻具有选择性,中和掉大点晕的壁电荷量不同,导致不同的中心点周围电场强度不均,因此每个小点不在4个大点结构的中心"插空放电".     

一种D_(2h)对称性放电气隙中气体放电斑图的研究

介质阻挡放电系统中首次在具有D_(2h)对称性放电气隙中获得斑图.该放电气隙是由4个条型结构组成,每个条型都是由圆形和矩形交替排列属于D_(2h)点群,在圆形与矩形的放电气隙双重调制下获得斑图的演化是从D_(4h)向D_(2h)的转变,并实现一种可调控的等离子体光子晶体.本实验对圆形区域内的放电行为进行研究.采用高速照相机对其时空结构进行测量,结果表明,斑图Ⅱ是由中心点、边框点、晕三套子结构相互嵌套而成,晕的形状呈环状.用高速录像机对环状的晕进行拍摄,可以观察到晕是由随机放电丝组成.采用光谱仪分别对不同子结构的等离子体参量进行测量.最后用壁电荷理论解释分析了斑图形成的机制以及环状晕形成的原因.     

介质阻挡放电中D_(2h)超点阵斑图的研究

在介质阻挡放电系统中,首次观察到一个由六边形点阵和四边形点阵嵌套而成的D_(2h)超点阵斑图.采用高速照相机(ICCD)研究了D_(2h)超点阵斑图的时空动力学结构,分析可知:D_(2h)超点阵斑图是由六边形子点阵、晕和四边形子点阵相互嵌套而成,且在每个外加电压半周期内子点阵的放电顺序依次为:六边形子点阵、晕、四边形子点阵.通过分析演化过程中出现的一系列斑图,发现对称性的演化顺序为:D_(4h)-D_(4h)和D_(6h)的混合态-D_(2h)-D_(2h),演化过程中斑图的对称性逐渐降低.通过分析子结构的对称性发现六边形子点阵、晕和四边形子点阵均属于D_(2h)点群.利用发射光谱法采集了氮分子(N_2)第二正带系(C~3∏_u→B~3∏_g)的发射谱线和氩原子696.57 nm (2P_2→1S_5)处的发射谱线,并计算得到了D_(2h)超点阵斑图中不同子结构的分子振动温度和电子密度.结果显示3套不同子结构的分子振动温度和电子密度相近,由此表明3套不同子结构的等离子体状态基本相同.最后,用壁电荷理论对斑图的形成进行分析.     

介质阻挡放电中暗环白眼超四边形斑图的研究

本实验首次在双水电极介质阻挡放电装置中获得暗环白眼超四边形斑图.该斑图的每个四边形晶胞内都包含一个由黑色圆环围绕的中心亮点.这种黑色圆环围绕中心亮点的结构类似于白眼晶胞,称为暗环白眼.利用高速照相机研究暗环白眼超四边形斑图的时空结构.结果发现,暗环白眼超四边形斑图由4套不同的子结构相互嵌套而成,在每半个外加电压周期内,子结构的放电顺序依次为:中心亮点-亮点晕-顶点四边形-顶点连线.其中,暗环白眼是由中心亮点和周围的环形不放电区域组成的.利用壁电荷理论解释了暗环白眼超四边形斑图的形成机制和暗环的形成原因.     

介质阻挡放电的斑图和频域分析

采用双水电极介质阻挡放电装置,利用光学方法研究了6.06×104Pa氩/空气混合气体的斑图演化过程.结果表明随驱动电压从击穿值不断增加,斑图经历了一系列的演变过程:均匀放电、六边形结构、随机微放电丝结构、第二次六边形斑图、四边形斑图、条带斑图、最后又出现均匀放电.用二维傅立叶变换的方法把斑图变换到频域中,得到了频域下的斑图并对其进行了分析.     

超六边形斑图的4种形成途径

为了减弱在斑图形成时实验条件的限制,获得同一斑图的多种形成途径,利用双水电极介质阻挡放电装置,在空气/氩气混合气体放电中,观察到了超六边形斑图的4种形成途径.在不同气压和氩气含量下,研究了4种斑图包括不规则六边形斑图、六边形斑图、四边形斑图和四六边形共存斑图到超六边形斑图的演化.实验发现随气压及氩气含量的变化,它们向超六边形斑图演化时的出现范围由大到小依次是六边形斑图、四六边形共存斑图、不规则六边形斑图和四边形斑图.     

中等pd值介质阻挡放电中的六边形斑图

实验采用双水电极装置,在中等pd(p为气体的压强,d为放电间隙)值介质阻挡放电中观察到了六边形斑图.实验发现,随电压的升高,六边形斑图是由弥散放电模式演化而成.通过测量各模式的光电流信号,发现在弥散放电模式时放电脉冲是单个的,而出现丝状放电时光信号表现为多个脉冲,且放电脉冲个数随外加电压的升高而增加.     

气体成分对等离子体斑图的影响

采用双水电极介质阻挡放电装置,在大气压下研究了氩气和空气混合气体中气体成分对等离子体斑图(包括四边形斑图和六边形斑图)的影响.四边形斑图和六边形斑图的电压范围随着空气含量的增加而逐渐增大.实验测量了击穿电压随空气含量变化的关系.结果发现:击穿电压随着空气含量的增加而增大,但不成简单的线性关系.在氩气放电中,击穿电压值随着放电间隙的增大而增大.     

介质阻挡放电中的八边形结构

采用双水电极介质阻挡放电装置,在放电间隙d值较大的实验条件下进行了斑图实验,实验首次得到了稳定的八边形结构,并对其演化序列和时空动力学进行了研究.实验发现,随外加电压的升高,系统经历了随机分布放电丝-大半径放电丝-八边形结构-失稳的八边形结构的演化过程.通过对其时空相关性测量,发现八边形结构在每半个电压周期内有2次放电.为了进一步研究八边形结构,实验还给出了斑图随空气体积分数和外加电压变化的相图,以及八边形结构随气体压强和外加电压变化的相图.     

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     

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