高强混凝土多重复合芯柱恢复力模型研究

基于8根高强混凝土多重复合芯柱在低周往复荷载作用下的试验结果,考虑轴压比、箍筋间距、配箍率等因素,提出骨架曲线特征点理论计算模型.同时,考虑加载历程对芯柱性能退化的影响,根据试验拟合结果引入刚度退化模型,以反映各试件滞回曲线卸载刚度退化规律,给出恢复力模型滞回规则,并将滞回曲线模拟值与试验值进行对比.结果表明:骨架曲线...     

内蒙古夏尔楚鲁金矿床辉钼矿铼-锇同位素年龄及地质意义

本文为查明内蒙古夏尔楚鲁金矿床的形成时间,对金矿体中发育辉钼矿的5件辉钼矿样品进行了铼-锇同位素分析,所获同位素等时线年龄为263.8±4.4Ma,其MSWD值为1.3。鉴于辉钼矿呈浸染状和团块状分布于黑云母花岗岩中,并且与石英和钾长石呈共生结构关系,可以推测夏尔楚鲁金矿床和黑云母花岗岩的形成时间均为早二叠世,属海西期构造—岩浆活动的产物。     

About stability of libration points in the restricted photogravitational three body problem

Nonlinear stability of the triangular libration point in the photogravitational restricted three body problem was investigated in the whole range of the parameters. Some results obtained earlier are corrected. The method for proper determination of cases when stability cannot be determined by four order terms of the hamiltonian was proposed.     

Occurrence and Distribution of the Eggs and Larvae of Anchovy, <Emphasis Type="Italic">Engraulis japonicus</Emphasis>, in Jeju Strait,Korea, with Descriptions of Environmental Characteristics

The occurrence and distribution of eggs and larvae of anchovy, Engraulis japonicus, in Jeju Strait, Korea from May to November 2002 were investigated, and the relationships between the abundances of anchovy eggs and larvae and the oceanographic conditions, including meteorological data, were analyzed. During the sampling periods, the anchovy eggs occurred from May to October and about 95% of total egg abundance occurred in only two months from July to August, suggesting that the main spawning season of anchovies is confirmed in summer from July and August in Jeju Strait. The spawning area of anchovies gradually moved to the southern part of the survey area with time. The predominant anchovy larvae collected in this study were mostly smaller than 16.0 mm TL. Correlation analysis and multiple regression analysis showed that the anchovy egg abundance in the study area depended strongly on the wind conditions, especially less than 10 m/s, and increasing water temperature. Salinity variations also had significant effects on the abundance of anchovy larvae.     

A model of the gravitational field of Amalthea

Utilizing the topographic model of Jovian moon Amalthea (Stooke, 1994) and supposing that its mass density is constant we derived its basic geometrical and dynamical characteristics. For calculations the harmonic model of topography of the degree and order 18 was selected. The model appears to fit the entire surface to a mean accuracy of a few hundred meters, except in the regions localized around longitudes 0° and 180°. On the basis of the harmonic expansion of the topography we estimated the volume (V = 2.43 ± 0.02 km³) and the mean radius of topographyr ₀ = (79.7 ± 0.2) km. Generalized moments of inertia up to the order 2, principal moments of inertia and orientation of the principal axes with respect to the original reference frame were also calculated. The results show that although Amalthea has extremely irregular shape it may be treated dynamically as an almost symmetric body (B C). Finally, the set of the Stokes coefficients up to the degree and order 9 was evaluated. The results are verified by direct numerical integration.     

巴林左旗双尖子山银多金属矿床基本地质特征及成因机制

巴林左旗双尖子山银(铅、锌)矿床位于大兴安岭南段,为超大型热液脉型矿床,在时空分布上与中生代构造—岩浆岩关系密切。双尖子山银多金属矿化多呈席状、细脉浸染状、网脉—脉状在下二叠统大石寨组火山—沉积岩产出,并且构成似层状、(长)扁豆状、透镜状和囊状矿体。初步研究表明:与银多金属共生的绢云母和辉钼矿同位素年龄分别为146.9±1.9 Ma和162.6±2.6 Ma,与区域侏罗纪火山岩同位素年龄160~147 Ma基本一致。根据矿区外围白音诺尔花岗岩体锆石年龄142~115 Ma,可以推测双尖子山银多金属主成矿作用与侏罗纪构造—岩浆活动相关,而与后期大规模中酸性岩浆侵位并无直接的成因联系。根据矿床产出环境、矿化和热液蚀变特征的初步研究结果表明,双尖子山可能经历了多次矿化的叠加,其可能与古太平洋板块远程俯冲和中生代动力机制转换作用有关。     

海洋功能区划分级分类体系探讨

海洋功能区划是《中华人民共和国海域使用管理法》确立的一项重要制度。文章回顾我国海洋功能区划分级分类体系的发展历程,结合笔者编制浙江省市县级(区域性)海洋功能区划的工作实践,发现《全国海洋功能区划(2011—2020年)》、现行《省级海洋功能区划编制技术要求》和《浙江省市县级(区域性)海洋功能区划编制技术要求》的海洋功能区划分级分类体系存在不一致和模糊之处,其编码方式也有改进和优化的空间。据此提出海洋功能区划分级分类体系及其编码的优化建议,希冀为下一轮海洋功能区划分级分类编码提供参考。     

内蒙古撰山子金矿床地质、地球化学特征及成因研究

撰山子金矿床产出在赤峰-朝阳矿集区北段,是赤峰地区唯一位于兴蒙造山带内的金矿床,构造-岩浆控矿作用明显。金矿化主要受断裂控制,呈脉状、细脉状产出,矿化至少经历了三个阶段:黄铁矿-石英阶段、石英-硫化物阶段和石英-碳酸盐阶段。本次主要开展对撰山子矿区的矿(岩)石硫同位、铅同位素和氢氧同位素研究,讨论撰山子金矿床的基本特征及成因机制。研究结果表明:撰山子成矿流体主要以岩浆水和大气降水的混合水为特征,矿石中的硫和铅主要源于岩浆,部分继承了围岩的特征。需要指出的是,矿石铅同位素和撰山子岩体铅同位素组成具有良好的相似性,指示其具有同源性的成因联系。因此,撰山子金矿床可能为深部大规模富金的烧锅营子岩浆侵入活动的晚期隆起(撰山子岩体)的产物,可能为一个典型的与侵入岩有关的金矿床,而非造山型金矿。     

基于中位数法的抗差总体最小二乘估计

针对现有总体最小二乘抗差算法存在的缺陷,应用中位数法确定模型参数的初值,提出了对模型的观测向量与系数矩阵中的观测元素进行分类定权的思想,避免了中误差估计偏差与随机模型误差对等价权函数抗差性的影响。基于中位数法建立总体最小二乘抗差迭代算法,并结合算例对算法进行验证。结果表明,在相同观测样本条件下,本文提出的算法拟合的精度高于传统算法拟合的精度。     

Coversand and Pleistocene palaeosols in the Landes region,southwestern France

New sections in the coversand of the Landes region, southwestern France, show at least two main depositional phases corresponding to the Upper Pleniglacial and the Lateglacial, which are separated by palaeosols. The lower palaeosol, a gleyic to histic cryosol overlying a net of sand wedges and dated to ca. 23 ¹⁴C ka BP, testifies to a short occurrence of permafrost. Impeded drainage due to the frozen subsoil is assumed to be the main factor involved in lowered aeolian transport and soil formation. Pollen analysis indicates a shrub tundra‐type environment. The overlying coversand unit is associated with small transverse ridges or sheet‐like deposits, and corresponds to the maximal extension of the sands, Upper Pleniglacial in age. An incipient podzol developed on the dunes under a boreal pine forest, and has been dated to 11.5–12 ¹⁴C ka BP, i.e. to the Allerød period. This has been buried by the second coversand unit during the Younger Dryas, typified by abundant denivation features and root imprints. Although preliminary, the chronology of sand deposition in the Landes region appears thus to be roughly similar to that found for the other European coversands, showing that all were the result of similar western European climatic changes, i.e. repeated episodes of increasing aridity related to the Upper Pleniglacial and the Younger Dryas episode. Copyright © 2008 John Wiley & Sons, Ltd.