激光扫描与无人机一体化控制下的复杂体育场馆高精度三维重建     

杨俊  王志鹏  祝凯  李淑红  焉石  胡春梅 《测绘通报》2020,(12):21-26

针对复杂体育场馆外部精细建模在完整性和精度方面存在的问题,本文提出了地面控制、地面激光扫描、无人机建模控制一体化的高精度建模方法。首先应用特制标志建立区域内控制、扫描、无人机高精度一体化坐标系统;其次对地面多站激光扫描点云结合控制坐标进行区域整体平差配准,生成一体化坐标系统下高精度地面点云模型;然后应用无人机数据和控制点生成一体化坐标下的高精度顶部数据;最后融合两种数据生成对象完整高精度精细模型。试验证明,整体平差解算方法可实现多站点云的高精度配准,一体化控制可实现非同源异质数据高精度融合,解决了复杂建筑对象的高精度建模问题,具有很大的实用价值。  相似文献   

工程海域波浪特征分析方法比较     

王科华  任赵飞  周智鹏  李伟仪 《海洋工程》2022,40(3):149-158

通过选取两个典型海外工程项目案例,分别采用波浪特征参数法和波浪谱法对工程海域波浪条件进行分析,并比较这两种方法在作业波浪条件、波浪特征认知程度上的差异,以及对海港水域平面布置产生的影响。对于波浪能量在频域及方向上存在多峰谱情况的海域,基于全谱的波浪特征参数系列数据有可能出现以下两种情况:1)主峰波向掩盖次峰波向;2)主峰波向错配次峰周期。对于上述两种情况,若仅采用波浪特征参数法对工程海域作业波浪条件进行分析,并指导海港水域平面布置,则极可能忽略或误判个别敏感波向、关键频域段的部分波浪能量,从而误导设计,为后续项目运营埋下隐患。对于以上情形,宜采用波浪谱法深入分析工程海域波浪能量在整个频域及各个方向上的详细分布及构成,并对关键波向、关键频域段的波浪能量进行量化,评估其对海港水域平面布置的影响,从而最大程度地避免由于波浪输入条件误判带来的风险。  相似文献   

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE     

Zun-Lei Xu  Kai-Kai Duan  Zhao-Qiang Shen  Shi-Jun Lei  Tie-Kuang Dong  Fabio Gargano  Simone Garrappa  Dong-Ya Guo  Wei Jiang  Xiang Li  Yun-Feng Liang  Mario Nicola Mazziotta  Maria Fernanda Munoz Salinas  Meng Su  Valerio Vagelli  Qiang Yuan  Chuan Yue  Jing-Jing Zang  Ya-Peng Zhang  Yun-Long Zhang  Stephan Zimmer 《天文和天体物理学研究(英文版)》2018,(3)

The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at～10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.  相似文献   

Experimental and numerical investigation of local scour around a submerged vertical circular cylinder in steady currents   总被引：1，自引：0，他引：1  

Ming Zhao  Liang ChengZhipeng Zang 《Coastal Engineering》2010

Local scour around a submerged vertical circular cylinder in steady currents was studied both experimentally and numerically. The physical experiments were conducted for two different cylinder diameters with a range of cylinder height-to-diameter ratios. Transient scour depth at the stagnation point (upstream edge) of the cylinder was measured using the so-called conductivity scour probes. Three-dimensional (3D) seabed topography around each model cylinder was measured using a laser profiler. The effect of the height-to-diameter ratio on the scour depth was investigated. The experimental results show that the scour depth at the stagnation point is independent on cylinder height-to-diameter ratio when the later is smaller than 2. The increase rate of equilibrium scour depth with cylinder height increases with an increase in Shields parameter.  相似文献   

Higher-harmonic focused-wave forces on a vertical cylinder     

Yuxiang Ma  Guohai Dong  Marc Perlin  Shuxue Liu  Jun Zang  Yiyan Sun 《Ocean Engineering》2009,36(8):595-604

This paper considers higher-harmonic forces due to wave focusing on a vertical circular cylinder. A series of experiments has been conducted in a wave flume. The first six-harmonic components of the measured wave forces are analyzed using the scale-averaged wavelet spectrum. It is noted that due to the transient nature of focused (freak) waves, Fourier analysis would not provide equivalent information to that gleaned from the analyses used herein. The results for the experiments with very steep wave crests show significant amplitudes at the fourth and fifth harmonics. These harmonics exhibit amplitudes that are the same order as the second harmonic, but much larger than those of the third harmonic. The wavelet-based bicoherence is used to detect the quadratic nonlinearity of the measured forces. And the bicoherence spectra reveal the primary mathematical reason for the existence of the striking amplitudes of the fourth and fifth harmonics: the interaction between the lower-harmonic components couple more strongly with the fourth and fifth harmonics, thus the fourth and fifth harmonics glean more energy than those of the third-harmonic components. However, the physical explanation for this remains elusive.  相似文献   

临沂市做好集约用地文章保障经济可持续发展          下载免费PDF全文

庞西祥  臧运永  张永翼  孙延龙 《山东国土资源》2006,22(4):10-12

临沂市认真落实国土资源管理基本国策,成立了由市政府主要负责同志任主任的全市国土资源管理委员会。特别是适应国家加强宏观调控及建设节约型社会的要求,坚持科学发展观,把节约集约用地作为重中之重来抓,以稳步推进市辖区旧城、旧村改造为突破口,不断开辟存量土地挖潜和集约利用的新途径,走出了一条立足存量抓挖潜、节约集约促发展的用地路子,推动了全市经济社会全面、协调、可持续发展。1大力推进旧城旧村整合改造近年来,临沂市把旧城旧村改造作为提升城市形象品位,不断改善城乡居民生活条件和挖掘存量土地开发潜力的重要举措。两年来,全…  相似文献   

四川盆地东北部砂岩型铀矿石及铀的存在形式特征研究     

安然  焦志鹏  辛存林 《矿产与地质》2021,(1):90-95

四川盆地东北部砂岩型铀矿含铀层位为下白垩统苍溪组,主要矿化产在苍溪组第一韵律层下部砂岩或砾岩层中.岩矿鉴定表明,主要含矿岩性为细—中粒砂岩,砂岩矿物碎屑主要为石英,胶结物主要为方解石,含少量黄铁矿.扫描电镜和电子探针分析表明,含矿岩石中除了矿物碎屑石英、胶结物方解石和黄铁矿外,还含有钛铁矿、方铅矿和铀石.铀石为岩石中铀...  相似文献   

Geospatial Service Web: towards integrated cyberinfrastructure for GIScience   总被引：1，自引：0，他引：1  

GONG Jianya  WU Huayi  ZHANG Tong  GUI Zhipeng  LI Zhenlong  YOU Lan  SHEN Shengyu 《地球空间信息科学学报》2012,15(2):73-84

  相似文献   

地球内部物质组成及其性质的研究     

臧绍先  宁杰远 《地球物理学进展》1993,(2)

地球内部物质组成的研究涉及对地表现象的深入解释,与地球动力学、地球热结构及宇宙演化有着密切的关系.本文综述了这方面的研究结果及近期的进展,指出两种地幔模型的主要分歧点,讨论了地幔中的主要相变及与间断面的关系,对今后研究提出四点意见.  相似文献   

CHLOROPHYLL FLUORESCENCE RATIO F685/F735 IN BROWN ALGAE AND ITS VARIATION UNDER EXCITATION BY TWO TYPES OF LIGHT AND DEHYDRATION     

武宝玕  臧汝波 《中国海洋湖沼学报》1993,11(1):1-7

Calculation and comparative study of the chlorophyll fluorescence ratio F685/F735 in brown algae (Laminaria japonica, Underia pinnatifida and Padina crassa) excited by blue and green light showed that the fluorescence ratios were higher when the algae were excited by blue light (440 nm), but reduced obviously under green light (540 nm) excitation. The values also reduced under dehydration but could recover during rehydration if the stress was not serious. The variation of the fluorescence ratio under dehydration was mainly because changes in fluorescence emission at 735 nm were always sharper than those at 685 nm. The ratio was sensitive to stress and has potential as a stress indicator in phycological research. Measurement of the fluorescence excitation spectra showed that the only peak at 540 hm changed apparently during dehydration. It meant that the function of the Chl a /Fucoxanthin protein complex for energy transfer was easily inhibited by water stress. However, no variation of the ratio was foun  相似文献