Building modeling for 3D city model

New development in urban planning, cityscape, real estate management and the like, calls for new demands for 3D city model. There are so many objects in 3D city model such as building, river, road, and so on. The building model is very important in 3D city model. In recent years,a lot of research work about visualization has been done. In our opinions,visualization is only a part of 313 city model, while interactive operation about buildings is rather important as well. In order to implement interactive operation (create , edit, query,etc. ), good data structure and model must be developed.     

A 3-dimensional data model for visualizing cloverleaf junction in a city model

The research work has been seldom done about cloverleaf junction expression in a 3-dimensional city model (3DCM). The main reason is that the cloverleaf junction is often in a complex and enormous construction. Its main body is bestraddle in air,and has aerial intersections between its parts. This complex feature made cloverleaf junction quite different from buildings and terrain, therefore, it is difficult to express this kind of spatial objects in the same way as for buildings and terrain. In this paper,authors analyze spatial characteristics of cloverleaf junction, propose an all-constraint points TIN algorithm to partition cloverleaf junction road surface, and develop a method to visualize cloverleaf junction road surface using TIN. In order to manage cloverleaf junction data efficiently, the authors also analyzed the mechanism of 3DCM data management, extended BLOB type in relational database, and combined R-tree index to manage 3D spatial data. Based on this extension, an appropriate data structur     

Al_2O_3-SiC-C砖渣静态侵蚀后的显微结构分析

铁水预处理用鱼雷罐、铁水罐的炉衬多为Ａｌ２Ｏ３ＳｉＣＣ砖,随着铁水脱硫量的加大,耐火材料的侵蚀也较严重。而现在由于市场需要钢水中的磷含量要求较低,脱磷处理过程中由于国外多采用氧化铁系脱磷剂,氧化亚铁对石墨的氧化很大,对炉衬侵蚀也大,这就要求对Ａｌ２Ｏ３ＳｉＣＣ砖的性能进行改进以适宜工艺需要。国内对脱磷的研究较少,实际生产对铁水进行脱磷处理的厂家也很少。为探讨脱硫、磷剂对耐火材料的影响,本文对不同脱硫、磷剂侵蚀Ａｌ２Ｏ３ＳｉＣＣ砖后的残砖的显微结构进行了分析,探讨了铝碳化硅碳砖的侵蚀原…     

甘肃张掖白垩纪早Aptian期黑色页岩揭示的气候岁差驱动及其意义*

白垩纪中期是温室气候的典型代表,在该时期地球经历了深刻的环境变化。有研究表明白垩纪中期欧洲低纬(约20°~30°N)地区海相地层的黑色页岩呈现斜率信号,同一时期同样纬度的中国地区以陆相沉积为主,但陆相低纬黑色页岩的轨道尺度周期研究较少。因此本研究选择甘肃张掖南台子白垩纪早Aptian期下沟组黑色页岩(古纬度约23°N)作为研究对象,以CaCO₃含量作为高分辨率古气候替代性指标,利用平均频谱拟合差和年代标尺优化法分析了南台子早Aptian期下沟组黑色页岩段的轨道周期变化,并利用频谱分析方法对调谐后的时间域序列进行分析。结果显示南台子下沟组黑色页岩段以岁差周期为主导,与欧洲低纬地区相关研究显著不同。这一气候变化的探索不仅提供了中国西北地区白垩纪轨道尺度气候变化的新证据,而且也有助于更全面认识白垩纪中期低纬地区气候变化的驱动机制。     

高分辨率三维地震资料处理技术及应用

高分辨率地震勘探技术贯穿于野外采集、室内资料处理和解释各个环节。文章从三维地震资料处理角度出发,探讨高分辨率、高信噪比和高保真度处理的关键技术措施,即波场净化处理,振幅、频率和相位补偿,叠前反褶积,静校正和动校正及叠后频谱整形。最后以实际资料说明经高分辨率处理后,频宽达到350Hz,给解释人员提供优质剖面,为分辨小间距薄煤层奠定基础。     

岩体结构面计算机三维扩展模型研究

结合水电站工程采集岩体结构数据的特点,详细介绍岩体中结构面在空间上的扩展与延拓方法,即试图利用有限的地质数据,建立结构面的拟合函数,从而实现三维地质模型可视化。     

砖住宅楼系列模型地震模拟试验设计--多层砖房抗震性能三向振动台试验研究之一

为保障住户地震安全和进一步研究多层砖房的抗震性能,由企业出资与研究所合作,在三向振动台上进行以四幢砖住宅为一系列的模型试验.本文为其研究论文之一,着重阐述在系列模型的设计中和地震模拟试验中的关键技术以及试验的最终结果.     

THREE-DIMENSIONAL CALCULATION OF PARTICLE-LIQUID TWO-PHASE TURBULENT FLOW IN A HYDRAULIC TURBINE RUNNER

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1950—2000年中国地磁测量地磁图与地磁研究

为纪念“３９１２”建队三十周年,本文回顾了１９５０－２０００年中国地磁测量和地磁图,回顾了“３９１２”任务的光辉业绩,阐述了“３９１２”任务的学术意义和应用价值。     

Tree-Ring δD as an Indicator of Asian Monsoon Intensity

Oxygen and hydrogen isotopic compositions of meteoric water are known to correlate with surface air temperature, except in tropical areas. This relationship has been described using a number of terms corresponding to specific observations, such as latitude, altitude and seasonal effects. However, these temperature effects do not seem to apply to precipitation in monsoonal areas of Asia. Questions have been raised as to whether the isotopic composition of meteoric water can be used to reconstruct paleomonsoon intensity. Tree rings of two modern spruce trees (Picea meyeri) and a 10,000-yr-old timber (Picea jezoensis) were analyzed for hydrogen isotopic composition. On average, the older tree is depleted in deuterium by 45‰ compared to the modern trees. We attribute this isotopic depletion to the strength of summer monsoons, which were more intense in the early Holocene than at present. Although this study is not definitive, it suggests that paleomonsoon intensity can be reconstructed by direct or proxy methods that yield the oxygen or hydrogen isotopic composition of meteoric water.