钨铅矿在我国的发现及其晶体结构的精细修正

湖南瑶岗仙钨铝矿发现于1948年,但一直未作正式报道。最近笔者用里特弗尔德法对其进行了晶体结构的修正。瑶岗仙钨铅矿的a=b=0.544503(3)nm;c=1.20495(1)nm;α=β=γ=90°。经笔者对瑶岗仙钨铅矿晶体结构修正得到的氧原子坐标为:X=0.2637,Y=0.1137,Z=0.0706;W-O的键长为0.17826nm,O-W-O键角为123°和103°。     

Efficient paddy field mapping using Landsat-8 imagery and object-based image analysis based on advanced fractel net evolution approach

This paper proposes an efficient paddy field mapping method using object-based image analysis and a bitemporal data set acquired by Landsat-8 Operational Land Imager. In the proposed approach, image segmentation is the first step and its quality has a serious impact on the accuracy of paddy field classification. In order to improve segmentation quality, a new segmentation algorithm based on a frequently used method, fractal net evolution approach, is developed, with improvement mainly in merging criteria. In order to automate the process of scale parameter determination, an unsupervised scale selection method is utilized to determine the optimal scale parameter for the proposed image segmentation approach. After segmentation, four types of object-based features including geometric, spectral, textural, and contextual information are extracted and input into the subsequent classification procedure. By using a random forest classifier, paddy fields and nonpaddy fields are separated. The proposed image segmentation method and the final classification result are both quantitatively evaluated. Our segmentation method outperformed two popular algorithms according to three supervised evaluation criteria. The classification result with overall accuracy of 91.00% and kappa statistic of 0.82 validated the effectiveness of the proposed framework. Further analysis on feature importance indicated that spectral features made the most contribution as compared to the other three types of object-based features.     

珙县某危险废物填埋场水文地质特征研究

本文根据在珙县某危险废物填埋场开展的野外调查工作和试坑入渗试验,结合前人在区内进行的水文地质普查成果,划分了研究区的含水层岩组与地下水类型,阐述了不同类型地下水的补给、径流和排泄等水文地质特征,并结合入渗试验测的渗透系数对包气带防污性能进行了初步评价,结果可知:研究区地下水类型可划分为碎屑岩类孔隙-裂隙水和松散岩类孔隙水两类,主要来源是大气降水补给,地下水动态随降雨变化明显,水量一般较少至中等,红层承压水在静水压力作用下向深部运动,通过机井揭露排泄,水量较丰富;利用双环试坑渗水试验可知,场址区粉质粘土层的渗透系数为0.011～0.013 m/d,渗透性等级为弱透水,防污能力较好。