基于Swarm卫星磁测分析全球地磁场垂直梯度

本文基于Swarm卫星磁测数据,使用沿轨差分数据近似垂直向梯度的方法,计算并分析北向分量(X)、东向分量(Y)、垂直分量(Z)在全球的实测垂直梯度:△X⊥存在负异常中心,△Y⊥大致呈现南北展布,△Z⊥为东西走向.将强度值和空间分布与CHAOS-6模型得到的模型垂直梯度进行对比分析.结果表明,实测垂直梯度与模型垂直梯度的...     

外加变位磁场作用GTAW焊接电弧的数值模拟

为了揭示外加变位磁场对GTAW焊接电弧的形态以及传热传质影响规律,建立了GTAW焊接电弧的数学模型;对比分析了无外加磁场,30°变位磁场,60°变位磁场作用下XZ截面(即Y=0截面)的电弧温度场、压强以及Z=7.5 mm截面电磁力矢量的变化规律;并在电弧空间取一条路径Path1(X方向),详细对比分析了此路径上的电流密度、电弧温度、X方向电磁力分量、Y方向电磁力分量、压强、X方向速度分量、Y方向速度分量的分布规律.结果显示:外加变位磁场作用下的XZ截面的电弧温度场、压强以及Z=7.5 mm截面电磁力矢量均不再呈现对称分布.在Path1上随着变位角度的增加,电弧X方向电磁力分量"波峰"上移、"波谷"下移;电弧Y方向电磁力分量由零变为"双峰分布",再变为"单峰分布",且"波峰"上移;电弧X方向速度分量由类似余弦函数分布逐渐变为"单峰"分布,且"波谷"下移;电弧Y方向速度分量由零逐渐变为类似正弦函数分布,且"波峰"下移,"波谷"上移.     

井中磁测钻孔底部异常特征快速分析

分析钻孔底部磁性异常体的不同产状、不同方向的磁异常场垂直分量及水平分量的空间分布特征,对磁异常进行解释,能有效地判断孔底磁性体的赋存情况,估算磁性体埋深。本文对不同产状(水平、向北缓倾、向南缓倾、向北陡倾和向南陡倾板状体等)磁性体(模板)产生的孔钻孔内底部磁异常特征归纳分析,总结井中磁测钻孔底部异常规律,为异常的解释及寻找深部磁性矿体提供参考。并将这一方法对泥河铁矿ZK0301孔实测曲线进行了分析。     

天然电场选频法的正演及在水库渗漏探测中的应用

对天然电场选频法剖面曲线开展正演模拟计算和实践应用工作,研究天然电场选频法剖面曲线的形成原因与实践应用的有效性.首先,采用矩形剖分、双线性插值函数对均匀半空间中的低阻异常体和高阻异常体模型开展有限单元法正演计算,分析地表沿测线方向上的二次电场分量随探测频率和异常体埋藏深度的变化规律;其次,将天然电场选频法应用于福建省南安市大湖水库的渗漏探测中,分析实测曲线与正演计算曲线之间的相似性.研究结果表明:现场实测曲线与理论曲线基本相似,说明天然电场选频法剖面异常主要是天然电磁场的二次电场分量所导致;同时,天然电场选频法是探测浅层低阻体的有效方法之一.     

线式天线本征解的研究

本文首先对导体的本征模理论及本征电流的计算方法进行了一般的研究,然后用矩量法对偶极天线、环形天线的本征电流、输入阻抗和辐射方向性图等进行了计算,得出通用计算机程序,其计算结果与有关结果比较具有良好的一致性。     

基于张衡一号电磁卫星数据对印尼Ms 7.4地震的研究

以2018年9月28日印尼Ms 7.4地震为背景, 利用张衡一号电磁卫星观测的ULF磁场X, Y和Z三分量数据, 采用滑动四分位(IQR)算法、滑动主成分分析算法(PCA)和短时傅里叶变换算法(STFT), 对震中范围的时空电磁数据进行分析, 结果显示 3 种算法都能有效地提取到震前异常。1) X,Y和Z分量均值震前7天开始出现异常, 随着发震时间临近, Y和Z分量的异常程度逐渐增加, 震前2天达到峰值, Y分量最大异常达到0.7 nT, 震后异常慢慢消失; 2) 震前5天主成分出现异常, 第一主成分占比急剧下降, 下降幅度超过15%, 第二、第三主成分占比急剧上升, 异常持续3天; 3) 震前9天, 13和25 Hz功率谱密度占比同时出现大幅异常, 13 Hz占比上升35%, 25 Hz占比下降超过40%, 13 Hz占比出现正异常, 最大正异常达到0.1, 25 Hz占比出现负异常, 最大负异常达到?0.15, 震后异常消失。结合同时段的太阳地磁活动情况, 认为上述电磁异常可以作为印尼地震的前兆。     

基于信噪比的FDM快速成型工艺参数优化分析

目的研究FDM快速成型系统中工艺参数,优化工艺参数寻找最优工艺参数组合,提高成型件X、Y、Z方向尺寸精度.方法依据六因素三水平L_(27)(3~(13))正交表安排成型方向、分层厚度、填充线宽等重要可控工艺参数对成型件X、Y、Z方向尺寸精度影响实验,并利用参数设计中信噪比分析方法对实验结果进行优化分析,确定X、Y、Z方向最优尺寸精度工艺参数组合.结果从X、Y、Z方向信噪比响应表可观察出X、Y、Z方向最优尺寸精度参数组合为A_2B_3C_3D_3E_3F_1、A_2B_2C_2D_2E_3F_2、A_1B_1C_3D_3E_1F_2.结论通过信噪比分析方法优化后的工艺参数可有效提高成型件尺寸精度,优化后的工艺参数具有广泛的适用性,对用户合理选择工艺参数提供参考价值.     

三维感应测井仪器在三维井眼环境中的正演模拟

分析三维感应测井仪器三线圈系视电导率受层边界、井眼钻井液、侵入和仪器偏心等因素的影响。结果表明:井眼对XX/YY方向视电导率的影响比ZZ方向显著;侵入对XX/YY/ZZ方向视电导率都有影响,且XX/YY方向视电导率偏移方向与ZZ方向视电导率偏移方向相反;井眼和侵入对XZ/ZX分量影响主要表现在边界附近;偏心对ZZ方向视电导率几乎没影响,但当测井仪器偏心在X方向时,YY分量的响应影响最大,而当测井仪器偏心在Y方向时,XX分量的响应影响最大。     

汽轮发电机定子内部故障的负序阻抗方向保护

现有的绝大多数汽轮发电机中性点侧只引出3个端子。通常装设的完全纵差保护只能反应相间短路故障,纵向基波零序过电压保护和故障分量负序方向保护等对匝间短路故障都存在较大的动作死区。为提高汽轮发电机匝间短路故障的保护动作率,通过分析机端等值负序阻抗在电机内部不对称故障和外部不对称情况下的不同规律,提出了基于相角范围的负序阻抗方向判据。在此基础上考虑到各种防误动措施,提出了一种新的发电机定子内部不对称故障保护方法——由负序电流启动的故障分量负序阻抗方向保护(Z2′)。运用"多回路分析法",对两台典型汽轮发电机所有可能发生的内部短路故障进行了仿真计算和灵敏度分析。结果表明,Z2′保护对定子内部不对称故障(尤其对内部匝间短路故障)的灵敏性和保护范围都优于现有的其他原理保护,能为只引出3个中性点的汽轮发电机提供高质量的保护。     

一种确定条带状激电异常场源体产状的向量法

提出一种确定条带状激电异常场源体产状的向量法,用于激电中梯法在野外准确快捷地确定板状场源体的产状。通过激电中梯扫面获得激电异常,结合地质资料确定场源体是板状体,选择三条中梯剖面,提取剖面上板状体中心平面的三个顶端坐标,三个坐标点如果不在一条直线则可以确定中心平面,利用空间解析几何法计算出中心平面的法向量,根据法向量中的实数对确定中心平面的产状。结果表明:该方法与传统的利用激发极化法确定板状体产状的方法相比,具有准确快捷、不需要进行复杂的反演、产状计算结果唯一等优点。该方法在云南省孟连铜矿区应用效果良好,按照该方法计算出的板状场源体的产状和坑道验证的产状基本一致,验证了方法的有效性、实用性。     

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.     

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