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提出了一种将图形生成技术与图像处理相结合,对DTM数据进行最优三角划分的简化DTM数据的算法。依据一定的分辨率条件,将DTM数据转化到二维图像空间,找到它的局部特征点,并将二维空间的特征点利用Delaunay剖分三角化,再映射到三维空间,从而在简化数据的同时,得到一个满足保真性要求的TIN模型。最后实验验证了算法的有效性。  相似文献   
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东濮凹陷南部沙三中段构造调节带对沉积体系的控制作用   总被引:1,自引:0,他引:1  
东濮凹陷是一个由其东部的兰聊断层拉伸活动造成的新生代伸展断陷盆地。构造调节带是东濮凹陷南部发育的主要变换构造类型。根据断层的组合特点与断距变化,归纳出4种倾向类型、3类叠覆类型,并根据其组合关系细分出11种构造调节带类型,且在东濮凹陷南部识别出其中的8种类型。东濮凹陷南部的构造调节带对沉积体系的发育有控制作用:西部斜坡带发育的同向调节带可作为物源通道,发育大面积的三角洲沉积体系;兰聊断裂带下降盘中的断鼻调节带也可作为物源出口,发育扇三角洲前缘沉积体系;中央隆起带中的背向调节带起分隔次级汇水盆地的作用。东濮凹陷南部的调节带形成机制与兰聊断裂的几何学与运动学特征有关,兰聊断裂的断面形态、活动差异及走滑运动分量是调节带形成的主控动力学机制。  相似文献   
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一、概 述我国一九五八年起自行研制液动冲击回转钻探设备及工艺技术。其工作的关键是研制性能优良的液动冲击器,目前经部级鉴定的已有12种,其中SC型、YS型和YZ型已逐步形成系列,性能达到或接近国外同类机型的先进水平,下表为地质系统这几个系列液动冲击器的主要参数  相似文献   
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陈维肖  刘玮辰  段学军 《地理研究》2020,39(10):2330-2344
当前,以“流空间”视角阐释现代交通运输方式在实现区域一体化中发挥的作用,通过关联性描述其网络空间组织过程,能为交通与城市体系互动发展提供科学支撑。基于此,以2000年以来铁路客运班次数据为依托,应用社区发现算法分析长三角城市群铁路客运网络及空间变化特征,结论如下:① 城市群发育出京沪社区、浙江社区、皖江社区和苏中北社区等子群,各社区内部为铁路客运联系的主要范围和方向,且表现出差异性空间联系格局变化;② 高内部联系社区具有较高外部社区间联系强度,枢纽城市间多发生跨社区高联系,形成不依赖于铁路可达性的“核心-边缘”式结构;③ 按空间特征将各社区分为单核心社区、双核心社区、多核心社区和无核心社区,从社区内联系模式看,核心城市数量不断减少、较高联系通道不断发育,但两者间存在不匹配;④ 从社区间联系模式看,高速铁路在增强跨社区交流过程中扮演重要角色,核心城市间联系增强,客运网络由通道指向转变为枢纽指向。  相似文献   
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Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources. In order to improve the utilization of zygotes and reduce the loss of seedlings, studies on the characteristic of the zygotes release, the development of rhizoids, the attachment of germlings, and the influence of jet washing were conducted. Results show that the percent of zygotes released was increased with time in the first 60 h. The capacity of germlings attached to the substratum was significantly increased, especially coincident with the time of the new rhizoids emerged and elongated. The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity. However, the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment. Our study provided some parameters to optimize the operation in the early stage of seedling production.  相似文献   
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根据现场调查和文献研究,武汉辖区内湿地生态系统存在的主要问题有:固化护坡加剧湖泊滨水带生态系统退化;湖泊生态系统植被指数下降,生态景观破碎指数增加;湖泊水质污染并致湖泊生态系统的生物多样性锐减。针对上述问题,在借鉴国内外湿地保护与可持续利用研究与实践的基础上,提出了武汉湿地保护与可持续利用的对策和建议。  相似文献   
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Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions;therefore,natural populations are likely to be multiclonal in a growing season.A recent field investigation showed that subordinate and ephemeral clones were able to establish populations in an environment with several strongly dominant clone populations.However,it was not clear how the subordinate populations maintained their growth under these conditions where the crowding signal would induce high levels of sexual reproduction in the dominant clone populations.In the present study,we conducted a continuous passage to 60 generations for new populations at three different temperatures(15°C,25°C,and 35°C).These populations emerged from resting eggs produced by a clone population.At the first,30th,and 60th generations,the populations were sampled and fitness was assayed using the life-table method.We found a significant short-term fitness advantage for populations newly emerged from resting eggs produced by a clone population of the rotifer Brachionus calyciflorus,followed by a significant decrease in relative fitness with long-term continuous passage.Our results suggested that the early shortterm fitness advantage was important for later-hatched and subordinate clone populations in an environment with multiple sympatric clones.The early short-term fitness might also promote the coexistence of sympatric clones because it could help to offset the cost of early sexual reproduction.  相似文献   
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We conducted a phenological evaluation of Sargassum thunbergii, a common algal species, along the coast of Lidao Bay, Rongcheng, China. The local S. thunbergii population entered a maturation period from early June to mid-August, when seawater temperature was 14.4 to 25.1°C. Our results suggest an increase in temperature and day length during this period initiated thalli maturation. Inhabitants of the low tidal zone had higher thalli length and biomass compared with those from the mid-and high tidal zones. We observed a switch in the length frequency distribution and contribution of length classes to biomass between the small (<20 cm) and long (20–79.9 cm) length classes at the time of thallus maturity. This suggests there is a trade-offbetween sexual reproduction and vegetative regeneration.  相似文献   
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