Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

The Qitianling calc-alkaline granite in Hunan Province (South China) has attracted much attention since the discovery of the Furong super-large tin deposit. The present study provides new mineralogical data to address their implications for exploration of tin deposits. In the Taoxiwo granite in the southeastern part of the Qitianling granite body, Sn-rich titanite was identified as an important type of Sn-bearing mineral. The titanite commonly occurs with biotite as euhedral crystals, exhibiting typical envelope-like shape and sector-zoning texture. These indicate that the titanite most likely crystallized in the magmatic stage. Electron-microprobe analyses show that the titanite is enriched in tin up to 1.12 wt% SnO₂, with an average of 0.43 wt%. With the crystallization of the granite, primary minerals undertook hydrothermal alteration by magma-derived fluids. Subsequently, in the hydrothermal stage, the primary Sn-bearing titanite was altered (at least partially), but still preserved its typical envelope-shaped outline. Micro-scale cassiterite is a representative product of such alteration; other secondary minerals include fluorite, ilmenite, Sn-bearing rutile and quartz. Therefore, the titanite, commonly present in the calcalkaline granites, can be treated as an important Sn-carrying mineral in the Qitianling granite, reflecting the primary magmatic environment with tin enrichment. The hydrothermal alteration of the primary titanite and subsequent crystallization of cassiterite recorded a process of leaching and accumulation of tin in magmatic-hydrothermal evolution of the Sn-bearing granite. Thus, this titanite has important implications for tin exploration. Supported by National Natural Science Foundation of China (Grant Nos. 40730423 and 40221301) and Project of China Geological Survey (Grant No. 1212010632100)     

Improving the Characteristic of the LaFeO_3 Alcohol Gas Sensor by Using Doping and Surface-Decorating Technique

采用掺杂和表面修饰技术制备ＬａＦｅＯ３乙醇气体传感器，明显地改善了传感器的特性．元件的灵敏度β≥１０（当乙醇气体浓度为２００×１０－６时），乙醇气体和汽油的分离度α为１４．３，在整个相对湿度变化范围内，元件阻值的相对变化在４％～６％之间，元件不通电存放７ｄ，其初期恢复时间为７０ｓ，不通电贮存２７０ｄ，其初期稳定时间小于３ｄ，在使用环境中连续工作９０ｄ其阻值相对变化率小于５％．     

集中供热热管太阳能集热系统

大面积集中供热已成为节能降耗的新途径 ,也是太阳能热利用发展的趋势。在原有铜铝复合板的基础上 ,试制了一种结合多层建筑的集中供热热管式太阳能供热系统。我们对该集热系统进行了设计 ,并对系统的性能进行了测试。该系统结合建筑 ,利用集热板价格低的特点 ,充分利用楼层的集热面积 ,结构上体现了集中供热的特点 ,热量互为补充 ,能得到足够的热水     

液压蓄能式波浪能装置发电系统的特性

分析了液压蓄能式波浪能转换器(WEC)的工作原理和优势;根据液压马达和永磁同步发电机的数学方程推导出了发电系统的4个基本特性,分析了蓄能器压力和发电机负载对转速、电压和功率的影响;针对液压蓄能式WEC发电系统的两种工作模式——恒电阻模式和恒转速模式,建立了液压蓄能式WEC发电系统的Matlab/Simulink仿真模型,并进行了仿真实验,结果验证了关于液压蓄能式WEC发电系统特性推理的正确性.     

2017年至2019年海北州植被覆盖度时空动态变化分析研究

本文旨在对2017年至2019年海北州的植被覆盖度变化进行分析,获得其相关的时空变化规律。基于2017年至2019年生长季多时相的GF-1 WFV遥感影像,提取植被覆盖度。为了分析不同覆盖度等级的植被的时空变化,本文将植被覆盖度分为全植被、高植被、中植被、低植被和无植被五个不同等级,并在每个等级内结合DEM数据进一步划分为高山、中山、低山进行分析。研究结果表明：(1)对于植被空间分布特点而言,相对于全植被、高植被、中植被和低植被,无植被的面积占比比较少;(2)在空间分布上,针对不同的海拔高度而言,中山区的植被覆盖度较高,低山区次之,高山区的植被覆盖度最少;(3)从年际变化的角度来看,试验区在2017至2018年和2018至2019年期间,均会出现全植被和高植被相互转化的趋势;(4)从同一年度的生长季的分析发现,试验区内的植被覆盖度在6月至8月呈现上升趋势,在8月至9月呈现下降趋势,相对于其他等级,全植被的变化更加符合该趋势。通过本研究,可为掌握海北州植被覆盖度的时空动态变化规律提供支持。     

淮海经济区国家高新区发展水平综合评价

构建了由经济规模、经济效益、创新能力3个一级指标以及18个二级指标构成的综合评价指标体系,运用熵值法对淮海经济区的5个国家级高新区的发展水平进行了综合评价.结果发现:5个国家级高新区发展水平存在差距,济宁高新区的发展水平最高,其次是徐州高新区,临沂高新区的发展水平最低.工业经济基础、研发投入、经济规模、结构效益等是影响高新区发展水平差异的主要因素.     

广西二叠纪的沉积与矿产概要

广西二叠纪沉积岩石类型有碳酸盐岩、碎屑岩、铁铝质岩、硅质岩及火山碎屑沉积岩等５种类型。古生物计有１９个门类，５５３属，１３２带（组合），１３１３种。沉积海域分属陆地－陆缘滨岸相、陆缘碳酸盐台地或碳酸盐缓坡相、弧立碳酸盐台地相、台地边缘相、台缘斜坡－浅水盆地相和半深水－深水盆地相等不同的沉积环境。其沉积古地理格局严格受岗瓦纳板块南移、碎裂和特提斯海的扩张影响，可分为石炭纪泛大陆晚期发展阶段（马平晚期     

水平螺旋管外V型槽强化冷凝传热的理论研究

对水平螺旋管外开有Ｖ型槽时的凝结换热强化问题进行了理论研究．针对Ｖ型槽的冷凝换热特点,将Ｖ型槽流动区域分为传热区和液流区两个部分,对其分别建立了理论模型,并进行了数学描写．通过分析两个区之间流动和换热的有机联系,得到了螺旋管外Ｖ型槽冷凝换热问题的理论解,并给出了能用于工程实际的换热准则方程式．     

软土地层桥梁群桩基础沉降模型

根据软土地层桥梁群桩基础的沉降特性,推导该地质环境下群桩模型试验相似法则,自行设计带承台群桩基础的室内模型并开展试验研究.试验结果表明:在桩身范围内,附加应力随深度衰减,在分布形式上,附加应力分布形式可近似为三角形;同时,桩侧土体的竖向应力随着桩顶沉降的增加而相应的增加,在接近极限荷载产生较大沉降时也没有表现出明显收敛的现象;群桩在施加荷载时(不同施工阶段),桩周上部分土中产生较大的超静孔隙水压力,随着时间逐渐消散,即土体的固结过程需要一定时间;群桩的荷载与沉降关系明显呈现非线性特性,其P-S曲线大致可以划分为线性阶段、屈服阶段和整体破坏阶段3个阶段;且通过试验可知卸载后,各群桩位移回弹很小,经外荷载作用后,产生较大的塑性变形,因而群桩沉降应作为桩基础设计控制条件之一.     

Multi-Dimensional Piece-Wise Self-Affine Fractal Interpolation Model

Iterated function system (IFS) models have been used to represent discrete sequences where the attractor of the IFS is piece-wise self-affine in R 2 or R 3 (R is the set of real numbers). In this paper, the piece-wise self-affine IFS model is extended from R 3 to Rn (n is an integer greater than 3), which is called the multi-dimensional piece-wise self-affine fractal interpolation model. This model uses a "mapping partial derivative" , and a constrained inverse algorithm to identify the model parameters. The model values depend continuously on all the model parameters, and represent most data which are not multi-dimensional self-affine in Rn . Therefore, the result is very general. The class of functions obtained is much more diverse because their values depend continuously on all of the variables, with all the coefficients of the possible multi-dimensional affine maps determining the functions.