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为掌握蒙古韭(Allium mongolicum)在中国的分布现状和种群发展趋势,采用野外踏查和栽培实验相结合的方法,对其地理分布范围进行了界定;以结实量调查数据为基础,分析了不同分布区域蒙古韭的结实特点以及影响因素。结果显示:(1)蒙古韭在中国的分布区约在36°28′—46°14′N、88°39′—116°05′E之间,包括陕西、甘肃、宁夏、内蒙古、新疆、青海6省(区)。(2)由于生境差异,蒙古韭不同群落中物种组成差异很大,蒙古韭多为伴生种或偶见种,很少为优势种。(3)不同生境条件下蒙古韭的结实特性差异较大,多数地区没有结实或结实率很小,主要是因为干旱导致其生殖生长受阻,加之人为因素干扰,使蒙古韭不能正常完成其生活史。 相似文献
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CHANG Zhaofeng LIU Shizeng ZHU Shujuan HAN Fugui ZHONG Shennian DUAN Xiaofeng 《资源与生态学报(英文版)》2016,7(2):130-136
Photovoltaic (PV) power generation is an emerging energy industry that is developing rapidly. A number of PV power plants have been established in the desert and Gobi areas in northwest China in recent years. Is there any ecological significance to the establishment of PV power plants? If yes, what is it? This paper tries to find the answer by analyzing meteorological data from the Hexi Corridor as well as the observational data of light and vegetation in the Minqin desert area. The results show that the solar energy converted from 1 m2 of PV panels is equivalent to the solar energy that is utilized by 260.75 m2 of desert plants in the desert area. In China, there is vast area of desert and Gobi, with frequent dust storms and aeolian sand, as well as rich sunlight resources. Therefore, to develop the PV industry in the desert and Gobi regions will not only create considerable economic benefits, but will also be of great ecological significance. On the one hand, PV can effectively regulate thermodynamic equilibrium on the surface, helping to prevent sandstorms and reduce aeolian sand. The development of the PV industry is a win-win that generates economic returns and provides ecological protection by combating desertification. On the other hand, the PV industry can be developed without taking up arable land or other types of land. There are frequently high winds in the desert and Gobi region. PV power plants, together with wind power generation, are useful to transform and consume the power source that creates duststorms and aeolian sandflow in the desert and Gobi areas. This results in fewer sandstorms and reduced aeolian sandflow. 相似文献
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车道线检测是自动驾驶汽车或高级驾驶辅助系统的重要组成部分,利用安装在车辆前方的单目相机以实时成像的方式获取车辆在当前车道的横向偏移,从而为车辆的车道保持、超车换道等横向控制策略提供参考。本文提出了一种基于双灭点估计的实时、稳健的车道检测方法。首先利用尺度自适应的局部对称算子对车道线点特征进行提取;其次对左右车道线分别估计灭点,以灭点为导向,构建特征点的统计直方图;然后选择穿过大多数特征点的直线且通过特征点和所选线之间的重叠度对灭点进行估计更新,重复上一步骤以获得稳定的灭点;最后基于稳定的灭点验证并选择最佳的车道线。本文在公共数据集对提出的方法进行了测试,试验结果表明,本文方法在满足实时性的前提下,能有效提高算法整体的稳健性。 相似文献
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Existing studies for site response analysis in geotechnical earthquake engineering have widely concentrated on the horizontal component of the ground motion. However, strong vertical ground motions have been repeatedly observed, resulting in significant vertical compression damage of engineering structures. Furthermore, for the seismic design of critical structures(e.g. large-scale dams and nuclear power plants), the ground motions in all three directions should be considered. Therefore, there is a need to investigate the site response subjected to the vertical component of the ground motion, especially for the seismic design of critical structures. Consequently, in this study, a numerical program for vertical site response analysis is proposed based on the commonly used analytical transfer function method. The proposed program is then validated against well-documented case studies obtained from the Japanese KiK-net(Kiban Kyoshin network) downhole array monitoring system. Results show that the response spectra at the ground surface are well predicted in the low frequency range(5 Hz), while discrepancies are observed in the high frequency range. However, the high frequency discrepancies do not significantly affect the overall prediction accuracy, as the overall seismic response of geotechnical structures are usually dominated by low frequency vibrations. Furthermore, the limitations in the analysis are also discussed. 相似文献
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河西走廊绿洲面积动态及其驱动因素 总被引：4，自引：3，他引：1
绿洲是干旱区脆弱生态体系中由人类活动与自然因素综合作用形成的、能够为人类生存与发展提供物源基础和生态服务功能的重要地理单元,其动态变化能够反映区域内生态、经济以及社会的演替方向。以第四次和第五次全国荒漠化和沙化监测数据为基础,结合同期气象与人类活动数据,应用转移矩阵与灰色关联度分析法,分析了河西走廊绿洲土地利用类型的转移规律和环境因素对绿洲动态变化的影响程度。结果表明:(1)研究时段内,河西走廊绿洲内部土地利用类型动态转移明显,相互间转化剧烈的地类包括耕地、居民工矿交通用地、有林地、灌木林地和草地;(2)河西走廊5个地级行政区绿洲面积均呈增加趋势,增加幅度最大的为嘉峪关市(51.97%),最小的为武威市(3.68%);(3)驱动河西走廊5个地级行政区绿洲面积动态变化的主导因子与农耕产业关系密切,预示河西走廊水资源利用与农业生产效率仍需提高。 相似文献
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