磁性层析成像──塔里木盆地（部分）地壳磁性结构反演

在磁源空间设计模型，建立模型磁化强度和磁场间的系数矩阵，研究磁性层析成像（ＭＣＴ）．模型和塔里木盆地（部分）磁场反演表明，磁性层析成像能够揭示岩石磁性的强弱，磁性体在三维空间中的位置和形态特征，展示不同深度的线性构造．     

地球磁尾中不同类型磁结构的磁螺度演化特征

在二维三分量MHD数值模拟的基础上 ,对地球磁尾不同类型磁结构的形成作磁螺度分析 .研究表明 ,对于由晨昏电场产生的磁尾驱动重联过程 ,通过系统边界输运的磁螺度通量是引起系统总磁螺度变化的直接原因 .不同的初始磁螺度密度分布和磁螺度通量输运 ,可以引起中性片区域磁螺度密度分布的不同演化 ,从而导致具有不同拓扑位形磁结构的形成 .     

磁通量浮现驱动磁场重联的数值研究

应用二维时变可压缩磁流体动力学数值模拟,研究了双极－单极磁场中由于磁通量浮现驱动的磁场重联过程．结果表明,双极场与单极场间磁力线的重联形成上升的冷而密的等离子体团,磁场演变成鞭状结构．向上运动的等离子体团到达其最大高度后将回落和弥散.等离子体团最大上升速度达０．１４ＶＡ,等离子体最大上升速度达０．２７ＶＡ,ＶＡ为下边界处的Ａｌｆｖｅｎ速度．随着磁通量浮现幅度的增大,等离子体上升速度增加,重联过程发展得较快．背景等离子体β１值（β１为等离子体压力与磁压之比）越小,等离子体团中密度增量越大．磁Ｌｕｎｄｑｕｉｓｔ数Ｓ在１０３－１０６之间的改变对等离子体的速度和密度增量影响并不明显．与电阻撕裂模不稳定性引起的自发重联相比,磁通量浮现会更有效地驱动双极－单极场中的磁场重联过程,寻致日冕Ｈα冲浪和Ｘ射线喷流的形成．     

亚热带富铁土的磁学性质及其磁性矿物学

通过５５个亚热带富铁土的磁化率（χ）、频率磁化率(χ_ｆｄ)、非滞后剩磁（ＡＲＭ）和饱 和等温剩磁（ＳＩＲＭ）等磁性参数测定,结合氧化铁化学形态分析和矿物鉴定,初步明确了亚热 带富铁土的磁学特征及其磁性矿物．磁测数据表明富铁土中存在强磁性的矿物,其磁化率χ 与土壤游离氧化铁（Ｆｅ_ｄ）含量呈极显著指数正相关（Ｒ^２＝０．５９７１）,频率磁化率χ_ｆｄ与土壤游离氧 化铁含量呈极显著直线正相关（Ｒ^２＝０．４２８９）．富铁土的χ_ｆｄ和非滞后磁化率χ_ＡＲＭ。值表明土壤 中的磁性矿物以超顺磁性（ＳＰ）和稳定单畴（ＳＳＤ）颗粒为主,富铁上的χ和χ_ＡＲＭ呈极显著直线 正相关（Ｒ^＝ ０．９４２９）,证明富铁土的磁性是由风化成土过程产生的 ＳＰ和 ＳＳＤ磁性颗粒贡献 的．矿物磁测结合Ｘ－衍射证明富铁土中的氧化铁矿物由赤铁矿、磁赤铁矿和针铁矿组成。     

非滞后剩磁各向异性

由于非滞后剩磁各向异性和等温剩磁各向异性的参数直接与岩石中的携磁矿物颗粒有关,它比传统的磁化率各向异性更明确地指示岩石组构,在构造地质研究中有较大应用前景．本文介绍了非滞后剩磁及其各向异性的测定方法,并以一个实例阐述了它在构造地质中的应用．     

磁变仪布局的研究

本文提出了改进磁变仪布局的必要性和布局标准,对磁变仪定向及其稳定性、标度值稳定性和分量仪间允许的最小间距进行了研究,提出了可以提高磁变仪记录质量的改进布局和满足布局全部标准的新布局,改进布局特别是新布局可以显著提高磁变仪保持定向、抗干扰能力,获得记录标度值稳定的较理想的磁照图。     

A NEW METHOD OF CANCELLING MULTIPLE REFLECTIONS: “SOUSTON”*

Cancelling of multiple reflections by CDP stacking is generally incomplete. When the order of coverage is low, an improvement may be obtained by the use of special filters (e.g. Schneider et al: Geophysics 1965; D'Hoeraene: Geophysics 1966). But when the order of coverage is high, the efficiency of these filters is less obvious. On the other hand, the higher the order of coverage, the higher the efficiency in the solution presented. Schematically, our method includes three steps: Firstly: Searching for the multiple reflections. For this purpose Move Out corrections corresponding to the multiples are applied to each individual record, then CDP stacking is carried out. Secondly: Cleaning up of the individual records. “Decorrections” are firstly applied, then multiples are subtracted. For this, subtraction is weighed versus the energy of the multiples, that is to say versus the correlation between the original record and the pure multiple reflections. Thirdly: Normal processing with the cleaned records which have been obtained. The different steps of this method are illustrated with the help of theoretical examples. Its efficiency improvement in regard to normal CDP stacking is then demonstrated by means of true examples.     

PHYSICAL ASPECTS OF THE “AIRPULSER” AS A SEISMIC ENERGY SOURCE*

During the last few years the airpulser, or air gun, has become very common as an energy source for marine seismic surveys. This paper describes the physical processes which take place during the operation of the pulser and develops theoretical results concerning the energy and frequency of the radiated signal and the amplitude decay of the secondary bubble pulses. The theory takes into account the presence of the airpulser itself which is assumed to be a rigid sphere within the bubble of released air. The theoretical results are combined and compared with measurements made of the pressure within the airpulser, the acceleration of the body of the pulser, and the amplitude and frequency of the signal radiated into the surrounding water. A formula for calculating the bubble frequency is given and a diagram made of the energy partition between mechanical losses, radiated energy, etc. Finally, a comparison is made of the energy release from the airpulser with that from TNT.     

Magmatismes basiques dits “orogeniques” et “anorogeniques” et teneurs entro2: Les associations “Isotitanees” et “anisotitanfes”

The patterns of variation of TiO₂ conent during magmatic evolution are different in the so called “orogenic” and “anorogenie” basic associations; these last terms, which are the cause of much misunderstanding, can be replaced by the terms “isotitaniferous” and “anisotitaniferous”.     

DIURNAL CORRECTIONS TO MAGNETIC SURVEYS—AN ASSESSMENT OF ERRORS*

The comparison of a group of continuous total field stations in Ireland with the record of the total field from Valentia Observatory enables the errors which would be involved in using the Observatory as a diurnal correction base to be examined. For the most part, for a single correction, these errors lie between ± 2 and ± 6 gammas. However, they have three notable characteristics: (i) they are not closely dependent on the magnetic ‘noisiness’ of the day, (ii) they are only marginally reduced by the application of station-base time differences and (iii), they are strongly related to differences between the amplitude of the daily magnetic variation at the station and at the base. A permanent geographical basis for the latter differences enables a system for the estimation of the errors to be proposed.     

均匀磁化多面体的磁场

本文研究了均匀磁化多面体的磁场,建立了总磁异常（△T）及其各分量(H_ax、H_ay、Z_a)的规格化解析表达式。这是由平表面围成的任意磁性体磁场的一般式。由它可以简化出各种规则磁性体的磁场公式。文中以有限长倾斜板状体磁场为例,说明了这个简化过程。 本文的多面体磁场解析式是由角点坐标和磁参数值表示出来的。鉴于它是边和面的二重累加和式,因此,在电子计算机上计算将十分方便。