分类： 计算机科学 >> 计算机应用技术 提交时间： 2018-01-23
摘要： 视觉跟踪是计算机视觉中的一个重要课题，近年来随着它在无人机、智能交通、人机交互等方面的深入应用，受到了研究者的广泛关注与研究，并取得众多的研究成果。在视觉跟踪中，目标特征表达作为最基础也是最重要的部分，直接关系着最终的跟踪效果，合适的目标特征表达可大大提升结果的准确性。本文对视觉跟踪中常用的目标特征表达方法进行了整理与归纳，将其分为了三类，分别为视觉特征、数学特征和以卷积神经网络为主的语义特征，并对它们进行了详细地分析和比较。其中，相对于视觉特征和数学特征，语义特征能够更加有效地体现物体内在类别信息，对形变、遮挡等均有较高的鲁棒性。同时，本文还提出了目标特征表达在复杂性、准确性和鲁棒性方面所存在的问题。
分类： 地球科学 >> 地质学 提交时间： 2018-01-23 合作期刊: 《古脊椎动物学报》
ZHU Xu-Feng
FANG Kai-Yong
WANG Qiang
LU Xiao-Hong
WU Wei-Qiang
DU Yan-Li
HUANG Zhi-Qing
WANG Xiao-Lin
摘要： The first clutch of Stalicoolithus shifengensis is described here. This incomplete dinosaur egg clutch in which three nearly complete eggs and two egg prints were preserved was discovered in the red deposits of the Sanshui Formation at a construction site near the sluice of North Village, Dali Town, Nanhai District, Foshan City, Guangdong Province, China. The eggs in the clutch are stacked with various ranges. Based on the characteristics of the eggshell, these eggs can be assigned to S. shifengensis. The discovery of S. shifengensis in the Sanshui Formation complements the clutch information about the oospecies as well as expands its paleogeographic distribution, and sets the foundation for discussing the diversity of dinosaur eggs in the Sanshui Basin.
分类： 农、林、牧、渔 >> 农艺学 提交时间： 2018-01-23 合作期刊: 《干旱区科学》
摘要： Limited water resources often result in reduced crop yield and low water productivity (WP). In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwater harvesting (ARH) techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year (2013–2015) field experiment was conducted under a typical sub-humid drought-prone climate in Yangling (108°24′E, 34°20′N; 521 m a.s.l.), Shaanxi Province, China, to explore the effects of mulching (same for summer maize and winter wheat) on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges (M1), a crop straw mulch in the furrows (M2), a transparent film mulch over the ridges and a crop straw mulch in the furrows (M3), a black film mulch over the ridges and a crop straw mulch in the furrows (M4), and a control with no mulch (CK). Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation. In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity (PP), with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield (maize and wheat yields combined) and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.
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