Information structure analysis for quantitative assessment of mineral resources and the discovery of a silver deposit

We propose an information-structure-analysis (ISA) method to quantify the correlations between quantitative and qualitative variables as well as within each type of variable. This method is applied to the evaluation of mineral resources in the western Zheijiang Province of China. The district contains a number of silver-bearing Fe–Cu–Pb–Zn mineral deposits near igneous complexes and FeCuPbZn zones away from the complexes. Silver anomalies occur not only in the known Fe–Cu–Zn–Pb deposits, but also in the country rock, suggesting the possible existence of silver deposits far from the igneous complexes.The tonnage distribution of silver is modeled by Monte Carlo simulation. This simulation is conducted on the basis of the correlations between silver (Ag) and lead (Pb), since no known data on silver is available. The known tonnage distribution of lead in 11 control cells was used to approximate the tonnage distribution of silver in the Monte Carlo simulation. With ISA and Monte Carlo methods, the total amount of potential polymetallic resources in 49 cells in the western Zhejiang Provice is predicted. Significantly, a deposit with about 24 tonnes of silver has been found within our exploration target area.     

震害现场紧急卫星通讯系统的研究和建设

本文研究了应用VSAT技术建立大震现场紧急通讯系统的设计和实施方案,规定了该系统应实现的功能。在此基础上,提出了建立我国未来陆地地震救灾移动卫星通讯计划,并对一些关键技术和为移动用户可能提供的通讯业务进行了讨论。     

CCD倾斜仪的差分式结构和电路细分方法研究

介绍通过差分式结构设计和脉冲延迟细分方法解决CCD水管倾斜仪的抗干扰能力较弱、分辨力不高等不足.     

南海海上搜救困难性评价

为保障船舶海上航行安全,结合GIS与模糊层次分析法,从海上搜救的自然环境和人文搜救力量2个方面选取9个因子建立海上搜救困难性评价模型,对南海海上搜救困难性进行评价。结果表明：1）自然环境影响下,南海海域搜救困难性具有“V”字形分布的特点,由东北向西南难度等级逐渐降低。2）在人文搜救力量影响下,南海海域的搜救困难性整体呈“东北－西南条带式”,难度最大的区域主要位于南海东北―西南的连线上,呈不规则环状向连线两侧递减。3）综合两方面因素,南海部分岛屿周围搜救难度偏高,主要受台风等恶劣天气及远离搜救基地的影响,而远海海域搜救难度在整体上为“东北－西南递减式”空间分布格局,最高和较高的区域由研究区东北延伸至西南,然后向西北、东南两侧递减。总体而言,南海研究区中近21.1%的海域搜救难度≥7级,仍需加强对搜救力量的部署与建设。     

Observations of the countercurrent on the inshore side of the Kuroshio northeast of Taiwan

Intensive current measurements in the area northeast of Taiwan indicate subsurface, southwestward flow existed between the inshore edge of the Kuroshio and the East China Sea continental slope. At 70 km away from Taiwan, this countercurrent has a mean speed about 30 cm s^–1 at mid-depth. Closer to Taiwan, the flow turns along with the topography, and subjects to sidewall and bottom friction. Both the magnitude and the vertical shear of this countercurrent are comparable with that inferred from hydrographic survey. The wind field features short-period (a few days) fluctuations associated with the cold front passages, however, this is not reflected on the current records. It appears that the countercurrent is fairly steady. Together with similar reversing flow found at places much further to the north, the overall pattern seems to be a general quasi-steady feature along most part of the shelf edge of the East China Sea.     

An alternative approach to the structural motion analysis of wedge-beam offshore structures supporting a load

For convenience of dynamic analysis, some offshore structures such as fixed-type platforms are often modeled as the wedge beams supporting tip lumped masses. It is well-known that, due to the effect of the surrounding water, the natural frequencies of a beam in air (or dry beam) are different from those of the same beam immersed in water (or wet beam). However, if the natural frequencies and the associated mode shapes of a dry beam are calculated by taking account of the “added mass” for the immersed beam, then the last natural frequencies and mode shapes will be equal to the corresponding ones of the wet beam. Based on the last concept, the closed form solutions for natural frequencies and the associated mode shapes of the dry beam were determined first, then the partial differential equation of motion for the wet beam was transformed into a matrix equation by using the expansion theorem and the foregoing closed form solutions of free vibration responses for the dry beam. Solving the last matrix equation will give the required natural frequencies and the associated mode shapes of the wet beam. The formulation of this paper is available for the fully or partially immersed double tapered beams with either circular, square or rectangular cross-sections. The taper ratio for width and that for depth may be equal or unequal. The numerical results of this paper were compared with the existing results or the finite-element-method results and good agreement was achieved.     

几种新的河网分维及其制图特征

利用分形几何原理，推导出几种新的河网分维，并讨论了它们的制图特征。     

Gas hydrate saturation from acoustic impedance and resistivity logs in the Shenhu area, South China Sea

During the China’s first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ∼10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity.     

毛乌素沙地南缘固沙灌丛下地表凝结水特征

尽管凝结水在干旱生态系统中所发挥的重要作用已被广泛关注,但对其在固沙灌丛下时空变化特征的研究仍然比较薄弱。为探明固沙灌丛对地表凝结水的影响,在毛乌素沙地南缘沙区选择3种典型固沙灌丛（沙柳Salix psammophila、柠条Caragana korshinskii和油蒿Artemisia ordosica）,以无固沙灌丛影响的裸沙作为对照,用微型蒸渗仪测定了固沙灌丛下不同位置（根部、1/2冠幅和外缘）和不同方向（东、南、西、北）上地表凝结水的形成和蒸发特征。结果表明：（1）与对照相比,固沙灌丛的存在显著降低了地表凝结水量,沙柳、油蒿和柠条灌丛下凝结水量分别降低了29%、32%和33%;(2)不同类型固沙灌丛下地表凝结水量由里向外均呈显著增加的趋势,但不同方向上地表凝结水量差异不显著;（3）固沙灌丛的存在减缓了凝结水的形成和蒸发过程,即凝结水自19:00开始形成,到次日08:00基本结束,至13:00—15:00蒸发殆尽,其形成过程整体上表现出增加—平缓—增加的趋势,柠条和油蒿灌丛下地表凝结水在03:00—05:00甚至有少量蒸发,而蒸发过程呈稳定下降趋势;（4）凝结水的形成过程与空气...     

中国中部全新世古地磁长期变和相对古强度研究

高分辨率的古地磁场长期变（Paleomagnetic Secular Variation,简称PSV）和相对古强度（Relative Paleomagnetic Intensity,简称RPI）研究是解决全新世湖泊研究定年难题的有效途径之一,也能为认识区域古地磁场的变化提供不可或缺的基础数据。然而,目前我国中部地区仍缺少年代序列可靠、时间分辨率在百年尺度的全新世PSV和RPI记录。先前的研究显示山西宁武公海全新世岩芯具有稳定的粉砂质粘土湖泊沉积,并通过25个（本文在全新世时段用到18个）陆生植物残体AMS ¹⁴C测年建立了可靠的高分辨率年代序列,为重建高质量的全新世PSV和RPI记录提供了良好条件。本文通过特征剩磁磁倾角的变化建立了PSV序列,利用磁化率（χ）、非磁滞剩磁（ARM）、饱和等温剩磁（SIRM）等环境磁学参数对特征剩磁强度（NRM_25mT）进行归一化,估算了RPI变化序列。结果表明,公海全新世湖泊沉积物的PSV和RPI记录与北半球其他湖泊和海洋记录具有较好的一致性,同时存在着显著的区域差异,可以作为我国中部地区湖泊沉积的对比曲线。