Determination of the Total Content of Arsenic, Antimony, Selenium and Mercury in Chinese Herbal Food by Chemical Vapor Generation-Four-Channel Non-dispersive Atomic Fluorescence Spectrometry.

Food security is related to safe and nutritious food which meets people's dietary needs and food preferences for an active and healthy life. A simple and feasible method was proposed for the simultaneous analysis of trace arsenic (As), antimony (Sb), selenium (Se) and mercury (Hg) in Chinese herbal food by chemical vapor generation coupled non-dispersive atomic fluorescence spectrometry (CVG-NDAFS) in this paper. The operating parameters, such as observation height, carrier and shield gas flow rate, were optimized. The detection limits were obtained under optimal conditions, which were 0.051, 0.034, 0.050 and 0.0058 ng mL-1, respectively for As, Sb, Se and Hg. The relative standard deviations were 0.42%, 0.74%, 0.97% and 1.0% (n = 7), respectively (10 ng mL-1of As, Sb, Se and 1 ng ml-1of Hg). The proposed method is verified to simultaneously determine As, Sb, Se and Hg for Chinese herbal food.

A Hierarchical Building Segmentation in Digital Surface Models for 3D Reconstruction.

In this study, a hierarchical method for segmenting buildings in a digital surface model (DSM), which is used in a novel framework for 3D reconstruction, is proposed. Most 3D reconstructions of buildings are model-based. However, the limitations of these methods are overreliance on completeness of the offline-constructed models of buildings, and the completeness is not easily guaranteed since in modern cities buildings can be of a variety of types. Therefore, a model-free framework using high precision DSM and texture-images buildings was introduced. There are two key problems with this framework. The first one is how to accurately extract the buildings from the DSM. Most segmentation methods are limited by either the terrain factors or the difficult choice of parameter-settings. A level-set method are employed to roughly find the building regions in the DSM, and then a recently proposed 'occlusions of random textures model' are used to enhance the local segmentation of the buildings. The second problem is how to generate the facades of buildings. Synergizing with the corresponding texture-images, we propose a roof-contour guided interpolation of building facades. The 3D reconstruction results achieved by airborne-like images and satellites are compared. Experiments show that the segmentation method has good performance, and 3D reconstruction is easily performed by our framework, and better visualization results can be obtained by airborne-like images, which can be further replaced by UAV images.