Current Flows in Pulsar Magnetospheres

The global structure of current flows in pulsar magnetosphere is investigated, with rough calculations of the circuit elements. It is emphasized that the potential of the critical field lines (the field lines that intersect the null surface at the light cylinder radius) should be the same as that of interstellar medium, and that pulsars whose rotation axes and magnetic dipole axes are parallel should be positively charged, in order to close the pulsar's current flows. The statistical relation between the radio luminosity and pulsar's electric charge (or the spindown power) may hint that the millisecond pulsars could be low-mass bare strange stars.     

Fluid Discrimination Based on Inclusion-Based Method for Tight Sandstone Reservoirs

Surveys in Geophysics - Fluid discrimination is challenging for reservoir prediction, especially for tight sandstones with special petrophysical properties. In this paper, we first review the...     

环境因素对兴-贝型多年冻土分布与发育的影响

兴安岭-贝加尔（兴-贝）型多年冻土处于欧亚大陆高纬度多年冻土南缘,对气候变化和人类活动较为敏感。为了研究多年冻土变化规律以及预测其未来变化趋势,从环境因素对多年冻土的影响以及多年冻土与环境的相互作用两个方面出发,围绕地带性因素（纬度、高度、经度）和非地带因素（气温、植被、降水、积雪等）两大类环境因素的变化对多年冻土分布与发育的影响,分析了兴-贝型多年冻土的变化和发展趋势,总结认为：气温、植被、降水、积雪等环境因素共同作用,改变了土层水热状况,促使区域内大范围多年冻土经历了显著退化;退化程度存在区域差异,多年冻土南界附近退化程度最为显著。基于兴-贝型多年冻土的特殊性,提出了建立冻土和寒区环境监测机制并及时采取适应性和整治性措施保护和修复区域环境的建议。     

Retarding effect of concentration of cementation solution on biocementation of soil

Concentration of cementation solution (CCS) is one of the key factors influencing the cementation effect on soil improvement through the microbially induced carbonate precipitation (MICP) process. To precipitate more calcium carbonate per treatment, a higher CCS is needed. However, the MICP process may be retarded or even terminated with an increase in CCS. This retarding effect can be a major limitation for the MICP-based soil treatment and thus needs to be understood properly. This paper presents a systematic study on the conditions causing retarding and its effect on biocementation. The test results of this study have identified that there is retarding effect of CCS on the MICP process, showing that the calcium conversion efficiency, which represents the amount of calcium that has been converted into calcium carbonate in each treatment, reduces with the increase in CCS, and the concentration of calcium is the control factor. The retarding effect will dominate increasingly when CCS is higher than 1.0 M and the amount of calcium carbonate precipitation will reduce for the given amount and type of bacteria used in this study and become zero with CCS of 2.5 M. For the same calcium carbonate content, the unconfined compressive strength is greater for sand treated using a lower CCS as the contribution to the bonding strength by the calcium carbonate generated under a lower CCS is greater than that under a higher CCS.

     

Python在图像处理中的应用

Python是一种面向对象、直译式的计算机语言,虽然仅有十多年的发展历史,但是因其具有丰富和强大的库,成熟且稳定,具有一次编译,处处运行的通用特性,使用越来越广泛。本文针对数字图像处理的特点,利用Python语言,探究其在灰度变换、图像直方图、直方图均衡化、图像平均及高斯模糊中的应用,相比其他语言具有简单、快捷、易于学习的特性,并实例说明Python在图像处理中的技巧和方法。     

基于BD970 OEM板的精密单点定位功能实现

针对目前精密单点定位技术主要基于PC端事后解算或采用静态模拟动态的技术模式,在实际工程应用中难以满足对实时性和动态性的需求。文中采用Trimble BD970OEM板和Raspberry Pi单板计算机搭建嵌入式接收机平台,将实时精密单点定位程序移植到该平台上,通过无线网络获取信息工程大学iGMAS分析中心提供的实时轨道产品和实时钟差产品,进行实时精密单点定位实验。结果表明,X、Y、Z平均统计精度分别为0.22m、0.32m、0.33m,实现分米级定位,结果与目前已知嵌入式终端产品精度相当,能够满足接收机测量要求。     

准噶尔盆地中新生代砂岩型铀矿地层沉积特征与产铀远景预测

分析准噶尔盆地周缘中新生代的地层结构、含铀"泥-砂-泥"结构、含铀沉积类型及展布特征,认为垂向上叠置的湖退进积-湖进退积组合所形成的"泥-砂-泥"结构为大尺度上定位砂岩型铀成矿的有利地层结构,其中低位体系域(湖进退积)形成的辫状河-辫状河三角洲沉积是盆地砂岩型铀矿最为有利的沉积相带。主物源、转换带以及相带的变化进一步控制了砂岩型铀成矿的有利区分布:(1)原生灰色(还原)沉积地层中有利砂体分布往往受到主物源以及构造转换带的影响,主物源方向的河道砂体及构造转换带处的富砂区域是砂岩型铀矿主要的远景区域;(2)杂色沉积地层中的有利砂体分布主要受局部沉积环境变化的影响,有利砂体多发育在局部沉积相带突变(砂岩层有机质含量增加)的区域。     

渤海湾盆地冀中坳陷古潜山的三维地质结构特征

地质结构研究是开展盆地分析与油气勘探的重要基础。渤海湾盆地冀中坳陷以古潜山油气田著称于世,潜山地质结构的精细研究是深化油气勘探、进一步获得油气发现的关键。本文基于对覆盖整个冀中坳陷的2D 和3D 高精度地震资料的系统解释及对钻达潜山的数百口探井资料的综合整理与分析,开展了潜山地层与断裂系统的精细解析,整体揭示了潜山的三维地质结构。研究表明,冀中坳陷内发育长城系底、寒武系底、石炭系底、中生界底、古近系底和新近系底6个区域性不整合面,据此,在纵向上划分出7个构造层。冀中坳陷内切穿潜山顶面的断裂按其走向可以分为NE、NW 和近EW 向3 组。其中,NE 向断层最为发育,NW向断层多发育于坳陷中部偏东。以近EW 向的徐水-安新断层和衡水断层为界,将冀中坳陷分为北、中、南3 段,各段的构造样式存在明显的差异。从潜山成因类型的角度出发,根据潜山的地层组成、构造演化、控山断层及潜山本身几何学特征等因素,在坳陷内划分出42个潜山构造带,并详细总结了重点潜山带的发育特征。前中生代的构造-沉积演化为潜山的发育奠定了良好的物质基础,印支运动和燕山运动早期的挤压事件对潜山地层有着明显的改造作用,晚侏罗世以来的多期伸展控制了坳陷内不同成因类型潜山的形成-调整-定型过程。     

Diagenetic differences in tight sandstone reservoirs in two delta fronts: an example from the Chang 4 and 5 members of the Yanchang Formation in the Longdong area,Ordos Basin,China

With the intensification of oil and gas exploration, tight sandstone reservoirs have received an increasing amount of attention, particularly with regard to the genesis of tight reservoir rock. The Upper Triassic Yanchang Formation in the Longdong area of the Ordos Basin has developed a typical tight, oil-bearing, clastic reservoir (lithic arkose and feldspathic litharenite, grain size is mainly 0.1~0.3 mm in diameter). During the depositional period of the Chang 4 and 5 members, the two provenance systems of the southwest and northeast developed in the study area. In the southwest, sandstones in the lower part of distributary channels are coarser with fewer quartz overgrowth and ankerite and better reservoir quality (porosity about 12%, permeability about 1 mD). In the northeast, chlorite coating is thicker (>?4 vol%) in the underwater channel sandstones (porosity is about 14%, permeability is about 2 mD) than in the mouth bar sandstones. Sandstones in the upper part of distributary channels are finer with lower permeability (about 0.1 mD). Authigenic ankerite mainly appears around detrital dolomite as an overgrowth. The SiO₂ in the quartz overgrowth most likely came from the transformation of smectite to illite and the dissolution of feldspar. In the northeast, only 2 vol% of chlorite rims significantly inhibited quartz overgrowth, but they probably blocked and delayed the dissolution of feldspars by acids. We present results here that show the diagenetic differences in sand bodies in delta fronts are influenced by sediment size, maturity, and the composition of framework grain; the materials that compose authigenic minerals mainly come from the alteration of sandstones. As a whole, the formation of tight reservoir rocks in the study area is closely related to sedimentary facies, composition of framework grain, cement type and content, and development of dissolution.