Shape数据模型的研究与实践

对应用较为广泛的Shape数据模型进行分析和研究,并且针对一幅全要素海图由于数据量大的原因导致读取和图形显示速度慢的问题,在实践中采用快速读取内存的方法,实现了数字海图的快速读取及显示,并且同以往循环读取方法进行了比较.     

短期线状集中分布地磁日变化感应电流异常机理初步解释——以2012年唐山4.8级地震为例

本文分析了2012年唐山4.8级地震前,震中附近出现的短期原地重现线状集中分布地磁日变化感应电流异常的时空变化特征,及其与地震、中-下地壳和上地幔高导层的关系,进一步证实了短期原地重现线状集中分布感应电流的走向与中-下地壳和上地幔高导层顶面界埋深走向一致,认为其机理可能是深部热流体的上涌导致壳幔高阻体出现带有上拱性质的拆离滑动,深部上涌的热流体和高导层内热流体侵入高导层内电阻相对较高的地区,高导层出现短时间高导电流通道,当地磁日变化感应电流扫描经过高导电流通道时,感应电流会呈线状集中分布于此,并基于趋肤效应分布于其顶面附近。由于重现异常是发生在震源下方中-下地壳和上地幔高导层的地震异常,且该异常不同于震源附近及其震源至地表的地震异常,因此对推进地震孕育与发生机理研究可能有一定作用。此外研究还发现,地震虽然主要位于重叠段的端部,但更有可能位于中-下地壳重叠段的端部,这一发现对日常震情跟踪中应用该异常确定未来地震位置有一定帮助。     

极地海区等距离正圆柱投影平面上等角航线的展绘方法

墨卡托投影由于其纬度渐长的特性导致在极地海区投影存在严重的长度变形,无法在南北纬80°以外高纬度海区航海图中较好地应用。将长度变形程度明显低于墨卡托投影的等距离正圆柱投影作为极地海区的海图投影,研究了该投影平面中等角航线在极地海区的展绘方法。建立了等距离正圆柱投影平面上等角航线方程并对其曲率进行了分析,推导了绘制一般曲线形态的"以直代曲"公式;最后提出了一种可满足给定精度要求的等角航线展绘算法。实验结果表明:该算法简单易行,可在海图编绘规范规定的误差范围内,实现等角航线的精确展绘。     

滇西思茅盆地景谷地区曼岗组石英颗粒表面特征及其指示意义

石英具有硬度大和化学稳定性高的特点,其颗粒表面特征能很好的反映沉积环境,通过扫描电镜观察石英表面微细特征是判别沉积环境行之有效的方法。思茅盆地白垩系曾一度被认为是陆相水成沉积,笔者通过野外识别及室内基础研究发现,景谷地区下白垩统曼岗组具有风成沉积特征,需对该套地层开展石英颗粒表面特征的系统研究来进一步确定其沉积相,研究结果表明:研究区曼岗组石英颗粒表面具有明显的风成特征,磨圆度高,普遍发育典型的蝶形撞击坑、新月形撞击坑、毛玻璃化表面,存在沙漠漆,极易与水成特征相区别;而其较强的溶蚀作用与沉淀作用则显示了当时干旱炎热的气候条件。在风成沉积确定的基础上,笔者再结合典型沉积构造,粒度分析、岩性特征等沉积特征进行综合分析,认为研究区曼岗组应属沙漠沉积。     

GPS实时监测和预报电离层电子含量

GPS能高精度地实时监测电离层总电子含量(TEC)变化，对纠正单频GPS接收机电离层延迟和监测电离层活动及其所反映的太阳活动规律具有重要意义．上海地区GPS综合应用网的建立，为监测长江三角洲地区电离层变化提供了宝贵的资料，利用这些双频GPS接收机的连续观测资料，可近实时地监测和预报该地区电离层总电子含量，其内外符精度和外推预报30分钟的精度均优于0.4m．     

Submicron polyphase inclusions in garnet from the Tananao Metamorphic Complex, Taiwan: a key to unravelling otherwise unrecognized metamorphic events

Kyanite and staurolite occur in the Tananao Metamorphic Complex as submicron inclusions in almandine‐rich garnet from a metamorphosed palaeosol weathering horizon, near Hoping, eastern Taiwan. Quartz, rutile/brookite and zircon are also found as associated submicron inclusions in garnet. Employing the reaction ilmenite+kyanite+quartz=almandine+rutile, and the breakdown of staurolite and quartz as thermobarometers, these submicron‐scale minerals formed at >8.3–8.8 kbar and < 660–690 °C. This P–T estimate is different from that (i.e. 5–7 kbar and 530–550 °C) derived from matrix minerals, which include almandine‐rich garnet, muscovite, chlorite, chloritoid, plagioclase, quartz and ilmenite. These results suggest that submicron inclusions in garnet‐like materials may record portions of the otherwise undocumented prograde path or provide information about previous metamorphic events and thus yield new insights into orogenic belts.     

利用地基GPS数据研究2006年12月电离层磁暴现象

利用中国大陆全球定位GPS台网数据和中国周边地区国际IGS站数据，研究了2006年12月中旬的 磁暴对中国大陆上空电离层的影响。结果显示,该磁暴对中国大陆上空电离层的影响并不显著。     

The radial structure of hot one-temperature accretion flows with advection

Considering nonthermal e^±-pair production, this paper is focused on the radial structure of hot one-temperature accretion flows with advection under the condition of small viscous parameter ( = 0.1) and low mass-accretion rates. Self-similar relations of hot flow with advection have been adopted. The authors have used a scheme, in which the two regions of accretion flow are calculated separately and then joined together. Some typical features of hot flow with advection have been confirmed, and several new results obtained: there exists a critical radius r_cr; the local cooling rate is inversely proportional to the square of the mass of the central object; the e^±-pair process affects significantly the radiation of hot flows with advection.     

Microstructural, chemical and textural records during growth of snowball garnet

The growth history of two populations of snowball garnet from the Lukmanier Pass area (central Swiss Alps) was examined through a detailed analysis of three-dimensional geometry, chemical zoning and crystallographic orientation. The first population, collected in the hinge of a chevron-type fold, shows an apparent rotation of 360°. The first 270° are characterized by spiral-shaped inclusion trails, gradual and concentric Mn zoning and a single crystallographic orientation, whereas in the last 90°, crenulated inclusion trails and secondary Mn maxima centred on distinct crystallographic garnet domains are observed. Microstructural, geochemical and textural data indicate a radical change in growth regime between the two growth sequences. In the first 270°, growth occurred under rotational non-coaxial flow, whereas in the last 90°, garnet grew under a non-rotational shortening regime. The second population, collected in the limb of the same chevron-type fold structure, is characterized by a spiral geometry that does not exceed 270° of apparent rotation. These garnet microstructures do not record any evidence for a modification of the stress field during garnet growth. Concentric Mn zoning as well as a single crystallographic orientation are observed for the entire spiral. Electron backscatter diffraction data indicate that nearly all central domains in the snowball garnet are characterized by one [001] axis oriented (sub-)parallel to the symmetry axis and by another [001] axis oriented (sub-)parallel to the orientation of the internal foliation. These features suggest that the crystallographic orientation across the garnet spiral is not random and that a relation exists among the symmetry axis, the internal foliation and the crystallographic orientation.