大气中尘埃层对电离层电场向下映射的影响

本文首先用分析解方法计算了高纬电离层对流电场向下映射,在平流层、对流层上的水平电场分布情况。地磁场作用使70km以上的电导率呈各向异性,但计算表明,这对极区对流电场向下映射的影响不大。最后,着重讨论了尘埃层使电导率大大下降对电场映射的作用。结果表明,高高度上的尘埃层能完全改变原有的映射图象,而30km以下的尘埃层影响很小。     

高压输电线路转弯处的工频电场

利用矩量法对高压输电线路转弯处线路上的电荷的分布和线路附近的电场分布进行详细的分析，并以此为依据编制了计算高压输电线路附近电环境的通用程序，对一实际三相线路的计算表明，计算结果与实测电场结果吻合较好。     

高压电容式套管电容芯子极板电场分布的研究

应用有限元法计算分析了高压引线、变压器升高座直径、涂层、极板位置、个数、厚度等因素对套管电场分布的作用.得出极板和均压球表面的电场分布规律以及在套管电场分布的计算中不可忽略的几个因素,为电场的准确计算以及套管的优化设计提供理论参考.     

细胞膜电场分布的一种模式

细胞膜电场分布是决定细胞膜通道开或关的重要参数。多年来对细胞膜的电场分布一直采用简化模式进行计算。本文提出一种更为真实性的模式,进行计算并导出细胞膜两边电场分布的积分解。在此基础上,对细胞膜两边的荷电分子或离子浓度所产生的电荷分布类型进行讨论。计算结果表明,电场分布依赖于膜的结构、离子浓度及温度。对简单的情况,可导出通道类似于一个电阻,通道内的电场分布可用一电路模拟。通道周围的电场可用一电偶极矩等效。     

多用途EMP模拟器的时域分析

多用途 EMP 模拟器已经取得较好的实验结果,本文通过求解任意细导线天线时域电场积分方程,建立 EMP 模拟器的数学模型,进而从理论上对模拟器上的电流分布及其产生的电场分布进行分析计算。理论结果与实测波形吻合较好。     

过压自保护晶闸管二维电场分析

应用有限元法,对两种不同门极结构的过压自保护光控晶闸管的电场分布进行计算机模拟,讨论了电场分布与结构参数的关系及其对过压自保护特性的影响.计算表明,无P~-层晶闸管的穴区最大电场同时受到穴径和穴深的制约,而有p~+层的晶闸管穴径对电场的影响可以忽略,穴区最大电场主要由穴深确定.理论和实验均表明,控制门极的穴径和穴深可以达到控制门极自保护特性的目的.     

分布源模型下源区电场的奇异性探析

本文通过对源区电场求解过程的分析，指出了产生源区电场求解的奇异性是由于不适当的微、积分算子交换次序所形成的．ＰＶ法并不能解决数值计算的奇异性困难．进而，提出了对电流分布Ｊ（ｒ）无任何限制且无奇异的新的电场积分公式     

栅片灭弧室电场的计算及其对灭弧性能的影响

用有限元法计算了小容量接触器灭弧室内部三维电场的分布，分析了不同的栅片放置方式对电场分布的影响，并通过试验研究了电场对电弧重燃的影响程度．分析和试验表明：将灭弧栅片竖直放置，触头灭弧区域电场分布最均匀；在弧后恢复电压电场作用下，电弧重燃率最低，燃弧时间最短     

栅片灭弧室电的计算及其对灭弧性能的影响

用有限元法计算了小容量接触器灭弧室内部三维电场的分布，分析了不同的栅片放置方式对电场分布的影响，并通过试验研究了电场对电弧重燃的影响程度，分析和试验表明：将灭弧栅竖直放置触头灭弧区域电场分布最均匀；在弧后恢复电压电场作用下，电弧重燃率最低，燃弧时间最短。     

大地地磁感应电流与大地电导率关系的分析

磁暴产生的地磁感应电流(Geo-magnetically Induced Current,简称GIC)不仅在电网、输油气管道等导体中流动,还在大地中流动,研究大地GIC与大地电导率关系,对认识大地电导率对大地GIC和管网GIC的影响,以及准确计算管网系统的GIC具有重要意义。本文利用均匀大地电导率模型和分层大地电导率模型分别计算了不同深度大地GIC大小以及GIC分布规律,分析了均匀大地电导率模型和分层大地电导率模型与大地深层GIC的关系以及对GIC计算结果的影响。研究结果表明,大地电导率越小,大地GIC分布的深度越深,以及大地电性构造对大地和管网GIC大小和分布深度的影响很大。在此基础上,提出了下一步的研究建议。     

Nonlinear dispersive scale Alfvén waves inmagnetosphere-ionosphere coupling: Physical processes and simulation results

Dispersive Alfvén waves(DAWs)have been demonstrated to play a significant role in auroral generation of the magnetosphereionosphere coupling system.Starting from a two fluid reduced MHD model,we summarize the frequency,temporal and spatial characteristics of magnetospheric DAWs.Then,the nonlinear kinetic and inertial scale Alfveén waves are studied,and we review some theoretical aspects and simulation results of dispersive Alfve′n waves in Earth’s magnetosphere.It is shown that dispersive standing Alfve′n waves can generate the field-aligned currents which transport energy into the auroral ionosphere,where it is dissipated by Joule heating and energy lost due to electron precipitation.The Joule dissipation can heat the ionospheric electron and produce changes in the ionospheric Pedersen conductivity.As a feedback,the conducting ionosphere can also strongly affect the magnetospheric currents. The ponderomotive force can cause the plasma to move along the field line,and generate ionospheric density cavity.The nonlinear structuring can lead to a dispersive scale to accelerate auroral particle,and the Alfvn waves can be trapped within the density cavity. Finally,we show the nonlinear decay of dispersive Alfvén waves related to two anti-propagating electron fluxes observed in the auroral zone.     

Solar cycle dependence of the seasonal variation of auroral hemispheric power

Although much has been done on the hemispheric asymmetry (or seasonal variations) of auroral hemispheric power (HP), the dependence of HP hemispheric asymmetry on solar cycle has not yet been studied. We have analyzed data during 1979–2010 and investigated the dependence of HP hemispheric asymmetry/seasonal variation for the whole solar cycle. Here we show that (1) the hemispheric asymmetry of HP is positively correlated to the value of solar F10.7 with some time delay; (2) it is closely related to the coupling function between the solar wind and magnetosphere; and (3) the winter hemisphere receives more auroral power than the summer hemisphere for K _p～0 to 6. The statistic results can be partly understood in the framework of the ionospheric conductivity feedback model. The similarity and differences between our results and previous results are discussed in the paper.     

Locating the polar cap boundary of postnoon sector from observations of 630.0 nm auroral emission at Zhongshan Station

We studied the ground observations of 630.0 nm auroral emission at Zhongshan Station to determine the polar cap boundary with the latitudinal profile of emission intensity. The open-closed field time boundary is assumed to lie at the boundary between polar rain and plasma sheet precipitation. We assume that nonprecipitation-dependent sources of 630.0 nm emission cause a spatially uniform luminosity in the polar cap and that auroral zone luminosity is also spatially uniform. Therefore we determine the location of the polar cap boundary of postnoon sector from the auroral emission data each time by finding the best fit of the observations to a step function in latitude and we produce a time series of the location of the polar cap boundary. The average error of the practice in the paper is less than 0.8 degree. Foundation item: Supported by the National Natural Science Foundation of China (No. 40044013) Biography: Liu Li-gang (1976-), male, Master candidate, research direction: auroral physics.     

深浅侧向测井的联合反演

本文将地球物理中的三侧向测井模型归结为一个偏微分方程的反问题,并利用深浅三侧向测井电极系的电流与电位记录,给出了识别地层电阻率与泥浆侵入深度值的反演方法,这一方法可以为油田三侧向测井分析提供一个摆脱解释图版的途径。     

Dry mantle transition zone inferred from the conductivity of wadsleyite and ringwoodite

The Earth's mantle transition zone could potentially store a large amount of water, as the minerals wadsleyite and ringwoodite incorporate a significant amount of water in their crystal structure. The water content in the transition zone can be estimated from the electrical conductivities of hydrous wadsleyite and ringwoodite, although such estimates depend on accurate knowledge of the two conduction mechanisms in these minerals (small polaron and proton conductions), which early studies have failed to distinguish between. Here we report the electrical conductivity of these two minerals obtained by high-pressure multi-anvil experiments. We found that the small polaron conductions of these minerals are substantially lower than previously estimated. The contributions of proton conduction are small at temperatures corresponding to the mantle transition zone and the conductivity of wadsleyite is considerably lower than that of ringwoodite for both mechanisms. The dry model mantle shows considerable conductivity jumps associated with the olivine-wadsleyite, wadsleyite-ringwoodite and post-spinel transitions. Such a dry model explains well the currently available conductivity-depth profiles obtained from geoelectromagnetic studies. We therefore conclude that there is no need to introduce a significant amount of water in the mantle transition to satisfy electrical conductivity constraints.     

龙门山断裂带深部构造变形的粘弹性模拟分析

根据龙门山断裂带地区的构造特征,建立该地区二维有限元模型.在考虑到深部构造发生粘弹性蠕动的条件下,利用粘弹性接触的有限元方法模拟计算上、下地壳和上地幔的滑动情况.模拟结果表明,龙门山断裂带及周围是应力集中区域,且随着时间的推移应力集中程度加剧.模拟还表明龙门山断裂带断层深处滑动速率比地表的滑动速率大,平均为3倍左右.因此,在龙门山断裂带地表滑动速率较小的情况下,速率较大的断层深部物质在滑动过程中则会产生能量高度的积聚,当能量积累超过极限强度,断层产生滑动,从而引发了地震.     

中俄原油管道沿线冻土热学性质试验研究

导热系数是冻土热学性质中一项重要物理指标,它反映了土体传递温度的能力,是管道温度场以及下覆冻土融化圈的重要影响因素。导热系数的测量方法有很多,但不同试验方法对同一种土所测得的结果却存在较大差异。本文分别采用热线法、热流计法和比较法对中俄原油管道沿线的冻土原状样与扰动样进行了导热系数的测定,并对试验结果进行了回归分析。通过对比不同试验方法、不同土质类别等因素对导热系数的影响,分析对中俄原油管道工程沿线不同类型的管道地基土所采用的每种测量方法的适用范围。试验结果表明：对于同一种土,热线法的导热系数试验结果最大,热流计法的试验结果最小,而原状土样的试验结果则大于扰动土样的试验结果。可见,对细粒土扰动样的导热系数测量宜采用热线法,对细粒土原状样的导热系数测量宜采用比较法;而粗粒土由于受含泥量的影响,对扰动样的导热系数测量宜采用热流计法,对原状样的导热系数测量宜采用比较法。     

电火花线切割极间介电特性与放电能量分配关系

摘要：
建立了电火花线切割极间介质电阻模型,分析了加工能量与极间介质电导率、工件厚度之间的关系,并对极间介质电阻模型进行了实验验证.研究结果表明,随着电导率的升高或者工件厚度的增加,放电期间极间“漏电流”增大,损耗在极间介质的能量增加,加工效率降低,电导率变化导致的极间电阻改变对于加工效率的影响显著. 关键词：
电火花线切割; 工作介质; 介电特性; 电导率; 放电能量中图分类号： TG 662
文献标志码： A     

An interplanetary shock traced by planetary auroral storms from the Sun to Saturn

A relationship between solar activity and aurorae on Earth was postulated long before space probes directly detected plasma propagating outwards from the Sun. Violent solar eruption events trigger interplanetary shocks that compress Earth's magnetosphere, leading to increased energetic particle precipitation into the ionosphere and subsequent auroral storms. Monitoring shocks is now part of the 'Space Weather' forecast programme aimed at predicting solar-activity-related environmental hazards. The outer planets also experience aurorae, and here we report the discovery of a strong transient polar emission on Saturn, tentatively attributed to the passage of an interplanetary shock--and ultimately to a series of solar coronal mass ejection (CME) events. We could trace the shock-triggered events from Earth, where auroral storms were recorded, to Jupiter, where the auroral activity was strongly enhanced, and to Saturn, where it activated the unusual polar source. This establishes that shocks retain their properties and their ability to trigger planetary auroral activity throughout the Solar System. Our results also reveal differences in the planetary auroral responses on the passing shock, especially in their latitudinal and local time dependences.     

Water content in the transition zone from electrical conductivity of wadsleyite and ringwoodite

The distribution of water in the Earth's interior reflects the way in which the Earth has evolved, and has an important influence on its material properties. Minerals in the transition zone of the Earth's mantle (from approximately 410 to approximately 660 km depth) have large water solubility, and hence it is thought that the transition zone might act as a water reservoir. When the water content of the transition zone exceeds a critical value, upwelling flow might result in partial melting at approximately 410 km, which would affect the distribution of certain elements in the Earth. However, the amount of water in the transition zone has remained unknown. Here we determined the effects of water and temperature on the electrical conductivity of the minerals wadsleyite and ringwoodite to infer the water content of the transition zone. We find that the electrical conductivity of these minerals depends strongly on water content but only weakly on temperature. By comparing these results with geophysically inferred conductivity, we infer that the water content in the mantle transition zone varies regionally, but that its value in the Pacific is estimated to be approximately 0.1-0.2 wt%. These values significantly exceed the estimated critical water content in the upper mantle, suggesting that partial melting may indeed occur at approximately 410 km depth, at least in this region.