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51.
智慧景区三维数字沙盘基于数字高程模型、数字正射影像、数字矢量图等基础地理信息数据以及三维模型数据,通过添加旅游专题业务数据、视频监控数据、GPS定位数据,以真三维方式显示地表景观、景区各景点,实现地表地物地貌的立体显示,为景区管理人员在应急消防指挥时的辅助决策提供基础。  相似文献   
52.
"两违"综合治理工作因涉及范围广、频率高,亟须采取相应的数字化手段为工作开展提供技术支持。高分辨率遥感技术具有高空间分辨率技术特点,可为"两违"执法工作提供实时详尽的高分辨工作底图,加以遥感处理分析,可以达到对监控区域"两违"变化多时相监测的目的。本文设计了一套以遥感监测为主要手段,集成卫星遥感、航空遥感、无人机航测技术,从多源影像获取、多源数字正射影像工作底图制作、"两违"疑似图斑提取与建库到基于移动互联网技术的"两违"遥感地理信息系统开发的辅助城市规划监测服务体系。  相似文献   
53.
The Tibesti massif, one of the most prominent features of the Sahara desert, covers an area of some 100,000 km2. Though largely absent from scientific inquiry for several decades, it is one of the world’s major volcanic provinces, and a key example of continental hot spot volcanism. The intense activity of the TVP began as early as the Oligocene, though the major products that mark its surface date from Lower Miocene to Quaternary (Furon (Geology of Africa. Oliver & Boyd, Edinburgh (trans 1963, orig French 1960), pp 1–377, 1963)); Gourgaud and Vincent (J Volcanol Geotherm Res 129:261–290, 2004). We present here a new and consistent analysis of each of the main components of the Tibesti Volcanic Province (TVP), based on examination of multispectral imagery and digital elevation data acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Our synthesis of these individual surveys shows that the TVP is made up of several shield volcanoes (up to 80 km diameter) with large-scale calderas, extensive lava plateaux and flow fields, widespread tephra deposits, and a highly varied structural relief. We compare morphometric characteristics of the major TVP structures with other hot spot volcanoes (the Hawaiian Islands, the Galápagos Islands, the Canary and Cape Verdes archipelagos, Jebel Marra (western Sudan), and Martian volcanoes), and consider the implications of differing tectonic setting (continental versus oceanic), the thickness and velocity of the lithosphere, the relative sizes of main volcanic features (e.g. summit calderas, steep slopes at summit regions), and the extent and diversity of volcanic features. These comparisons reveal morphologic similarities between volcanism in the Tibesti, the Galápagos, and Western Sudan but also some distinct features of the TVP. Additionally, we find that a relatively haphazard spatial development of the TVP has occurred, with volcanism initially appearing in the Central TVP and subsequently migrating to both the Eastern and Western TVP regions. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   
54.
Black holes are extremely dense and compact objects from which light cannot escape. There is an overall consensus that black holes exist and many astronomical objects are identified with black holes. White holes were understood as the exact time reversal of black holes, therefore they should continuously throw away material. It is accepted, however, that a persistent ejection of mass leads to gravitational pressure, the formation of a black hole and thus to the “death of while holes”. So far, no astronomical source has been successfully tagged a white hole. The only known white hole is the Big Bang which was instantaneous rather than continuous or long-lasting. We thus suggest that the emergence of a white hole, which we name a ‘Small Bang’, is spontaneous - all the matter is ejected at a single pulse. Thus, unlike black holes, white holes cannot be continuously observed rather their effect can only be detected around the event itself. γ-ray bursts are the most energetic explosions in the universe. Long γ-ray bursts were connected with supernova eruptions. There is a new group of γ-ray bursts, which are relatively close to Earth, but surprisingly lack any supernova emission. We propose identifying these bursts with white holes. White holes seem like the best explanation of γ-ray bursts that appear in voids. We also predict the detection of rare gigantic γ-ray bursts with energies much higher than typically observed.  相似文献   
55.
用RT-PCR方法从1个H5N1亚型禽流感病毒分离株A/Chicken/Guangdong/DH/1997扩增NA基因cDNA片段,将其克隆至pMD18-T载体,获得重组质粒pMD-NA,并对其核苷酸序列进行测定和分析。结果表明,该毒株的NA基因长度为1350bp,编码449个氨基酸,与其它H5N1亚型AIV分离株的核苷酸序列同源性为97.0%~99.4%,氨基酸序列同源性为97.7%~99.1%,提示禽流感病毒NA基因保守性较高。NA基因氨基酸序列的聚类分析表明该毒株与来自香港的A/Pheasant/HK/FY155/01和A/Ch/HK/FY150/01两个分离株处于同一进化枝,亲缘关系较近。  相似文献   
56.
汪灵  胡晓宙  王哲皓 《岩石学报》2019,35(1):137-145
白度是矿物的重要光学性质之一。为了深化矿物的光学性质及白色矿物功能材料的研究与应用,根据测试分析结果和叶大年的结构光性矿物学理论,系统研究了影响矿物白度的主要因素,以及矿物增白效果的差异性及其产生机理。研究结果表明:(1)晶体化学是决定不同种类透明矿物白度的最主要因素,但对于某种透明矿物来说,影响其白度的主要因素是矿物中的碳质有机质、含铁钛矿物杂质、杂质元素的价态与晶体化学环境、介质环境、矿物中的水和粒度大小等。(2)证明了透明矿物白度大小与折射率呈正相关。白度相同的不同矿物的增白效果存在很大差异性,其根本原因是由矿物折射率所决定的反射率存在很大差别。(3)提出了真白度和假白度的概念,即主要由自色产生的白度称为真白度,主要由假色产生的白度称为假白度;真白度高的矿物具有增白作用,而真白度低的矿物,即使粉末白度高,也没有增白作用。(4)在影响矿物白度的主要因素中,矿物中的碳质有机质、含铁钛矿物杂质、杂质元素的价态等杂质成分对矿物白度和增白效果起负面作用。(5)矿物中与晶体结构相关的水所产生的颜色属于自色,脱去结晶水、层间水和结构水都有利于提高矿物的真白度或增白效果,但脱去沸石水的效果正好相反;由矿物粒度大小变化产生的颜色属于假色;通过降低粉体粒度大小所提高的白度属于假白度,由此增加的白度没有增白作用。另外,矿物粉体与使用介质之间的折射率大小差别越大,增白效果越明显。  相似文献   
57.
用6.0×104拷贝、1.2×104拷贝和6.0×103拷贝3种剂量白斑综合症病毒(WSSV)对凡纳滨对虾和斑节对虾进行人工注射感染,比较了两种对虾对WSSV敏感性的差异。结果表明,凡纳滨对虾死亡时间随病毒剂量降低而延长,斑节对虾死亡时间没有明显差异;随病毒剂量的降低,凡纳滨对虾人工注射感染后病毒复制高峰时间显著延长,斑节对虾感染后病毒复制高峰时间相同,WSSV在凡纳滨对虾体内比在斑节对虾体内复制慢。对虾携带WSSV数量最低为3.3×107拷贝.g-1,最高为4.3×108拷贝.g-1。凡纳滨对虾比斑节对虾对WSSV的抵抗性更强。  相似文献   
58.
风景旅游城市地名变更现象透析   总被引:6,自引:0,他引:6  
近年来,在旅游业的蓬勃发展中,旅游城市的更名是一种值得关注的现象。文章从地名学、心理学、历史学、文化学等不同角度出发,对这种看仅时尚实则混乱的现象进行剖析,认为旅游城市的更名要兼顾历史与现实,不能盲目地更名,否则全顾此失彼,以至产生认识、实用及管理方面的混乱。  相似文献   
59.
Seasonal mass balance components bw (winter balance) and bs (summer balance) as well as ct (total accumulation) and at (total ablation), can be used directly to infer climate variables. In contrast, ac (net balance of the accumulation area) and aa (net balance of the ablation area), and ba or bn (annual or net balance) can not. The traditional Alpine system of observations of ac and aa , however, can be converted to true seasonal values bw and bs if both pairs of components are simultaneously observed for some years, because a correlation between the two pairs of components exists. We analyzed bw and bs data and their mean, standard deviations and ratios of these to the corresponding net or annual balances for 50 glaciers with relatively long records representing different regions in the northern hemisphere. We also investigated correlations between seasonal components. A negative correlation between bw and bs exists at many glaciers. About two-thirds of the glaciers show insignificant correlations (?0.3 < r < 0.3), implying independence of summer and winter balances. In a few unusual cases the correlations are positive. These different correlations, or lack thereof, may offer insight into feedback conditions that must exist in this climate-related system. The correspondence of the bw and ct , and bs and at , appears to depend largely on the relative amounts of summer snowfall, a function of their climatic environment expressed as [α = (bw+bs)/2]. The contribution of variability of bs to the net balance increases markedly with decreasing values of α. The variability of bw and bs , and therefore the net balance, has been increasing with time; whether this is due to an increase in climate variability or to other causes is not clear. It appears that bw has been increasing with time at the highest altitudes, but bs has been increasing more rapidly especially at low altitudes; the many-glacier average net balance is becoming more negative.  相似文献   
60.
江苏省国内旅游线路节点配置研究   总被引:1,自引:0,他引:1  
基于旅行社旅游线路网络调查资料,本研究运用频数分析、聚类分析、比较分析等研究方法,深入分析了江苏省国内旅游线路中的城市节点、景区节点、临时节点等三大类旅游线路节点配置特征。结果表明:(1)可以将进入江苏国内旅游205条线路中的26个城市节点分为3个全国旅游热点城市节点、6个全国旅游城市节点、6个长三角区域旅游热点城市节点、11个省内短途旅游城市节点,南京和苏州是最主要的门户型和离境型城市节点;(2)随着客源地距离的增大,进入江苏国内旅游线路中的城市节点和景区节点数量都相应减少,旅游线路景区节点分布的地域集中性增强,相应城市节点内部的景区节点选择差异性也增大;(3)对游客具有较大吸引力的临时节点主要包括地方知名产品的生产和购物场所,以及富有当地文化特征的历史街区、现代CBD等。  相似文献   
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