排序方式： 共有35条查询结果，搜索用时 328 毫秒
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湖南桃源理公港地区白垩纪红盆内的灰绿色和紫红色沉积夹层曾选获过金刚石。以灰绿色岩石为研究对象,通过薄片鉴定和电子探针分析来确定岩石名称和岩石中石榴石和云母的属性。显微镜下,灰绿色岩石呈凝灰结构,由约45%的晶屑、35%的岩屑和20%的玻屑组成,为较典型的沉凝灰岩,并非前人所述的金伯利岩。沉凝灰岩中的石榴石和云母分别为G10型镁铝榴石和金云母,镁铝榴石和金云母的成分与辽宁、山东及南非典型岩管含金刚石金伯利岩中的镁铝榴石及金云母的成分基本一致,暗示其来源于含金刚石的金伯利岩。沉凝灰岩的特征表明,其来源地不会太远,这为在附近找寻火山机构奠定了基础; 金伯利质岩屑、G10型镁铝榴石和金云母的发现,为在周边寻找原生金伯利岩提供了重要信息。 相似文献
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本文通过大口径桩孔基岩钻进，探讨了ＰＺ系列组合式牙轮钻头结构特点、合理钻进参数的确定及碎岩机理。工程实践证明，牙轮钻头是我国目前大直径桩孔嵌岩施工较为理想的工具，应用效果良好。 相似文献
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北部湾广西沿岸全新世海侵过程的区域差异 总被引：2，自引：0，他引：2
通过分析北部湾广西沿岸3个地质钻孔的岩性、地球化学和有孔虫含量特征,确定了其沉积相序,在统一的高程坐标内,对各钻地层中沉积相的高程和年代进行了对比,分析了该区全新世以来海侵过程的区域差异;并以东亚全新世海平面波动曲线作为参照,估算了广西沿岸各主要海湾的构造沉降速度。研究表明:全新世以来,广西沿岸的海侵开始时间并不一致,这是由于各海湾构造沉降运动的区域差异造成的,东部的廉州湾构造基本稳定,而廉州湾以西则经历了较大幅度的构造沉降。构造沉降又导致了海平面波动过程的区域差异,进而影响到了地层形成,如海陆过度相沉积只发育于廉州湾以西遭受海侵时间较晚、相对海平面上升速度较低的区域。 相似文献
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Xun Liang Guangliang Chen Jiye Leng Youyue Wen Guangzhao Chen 《International journal of geographical information science》2020,34(10):1930-1952
ABSTRACT Modeling urban growth in Economic development zones (EDZs) can help planners determine appropriate land policies for these regions. However, sometimes EDZs are established in remote areas outside of central cities that have no historical urban areas. Existing models are unable to simulate the emergence of urban areas without historical urban land in EDZs. In this study, a cellular automaton (CA) model based on fuzzy clustering is developed to address this issue. This model is implemented by coupling an unsupervised classification method and a modified CA model with an urban emergence mechanism based on local maxima. Through an analysis of the planning policies and existing infrastructure, the proposed model can detect the potential start zones and simulate the trajectory of urban growth independent of the historical urban land use. The method is validated in the urban emergence simulation of the Taiping Bay development zone in Dalian, China from 2013 to 2019. The proposed model is applied to future simulation in 2019–2030. The results demonstrate that the proposed model can be used to predict urban emergence and generate the possible future urban form, which will assist planners in determining the urban layout and controlling urban growth in EDZs. 相似文献
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江苏省气象服务效益研究（Ⅱ）行业气象服务效益评估 总被引：1，自引：1，他引：1
行业气象服务效益虽有很多可以估量的典型事例，但更多的则是潜在于各行各业效益之中的难以测算的社会、经济、环境和生态效益，目前还没有一种完善的评价方法。本文采用德尔斐专家评估法，通过对分布于江苏省各市的一百多位行行业专家咨询调查，由１０８位专家有效投票的定性评估，得出了一个较为公正、客观、科学、可信的定量结果－－江苏省１９９２年行业气象服务的效益为２７．７３４７亿元，效益投资比为１１６．１，这项研究成 相似文献
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寿山叶蜡石矿床中叶蜡石的多型及其转变 总被引：4，自引：1，他引：4
叶蜡石具有1Tc和2M_1两种多型。寿山叶蜡石矿床中的叶蜡石不但具有普遍报道的2M_1型及1Tc与2M_1的混合型,而且具有同类矿床中少见的、但在本区却大量出现的1Tc型。本文对寿山叶蜡石多型变体的X射线衍射特征、镜下特征及化学成分特征作了写实性描述,指出本区叶蜡石存在着2M_1型向1Tc型转变的客观事实,并可能存在二者的中间类型;探讨了叶蜡石多型转变的条件,提出“表生溶液”是实现该转变的主要因素。 相似文献
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Urban growth simulation by incorporating planning policies into a CA-based future land-use simulation model 总被引：3，自引：0，他引：3
Xun Liang Dan Li Hui Zhao Guangzhao Chen 《International journal of geographical information science》2018,32(11):2294-2316
Urban land-use change is affected by urban planning and government decision-making. Previous urban simulation methods focused only on planning constraints that prevent urban growth from developing in specific regions. However, regional planning produces planning policies that drive urban development, such as traffic planning and development zones, which have rarely been considered in previous studies. This study aims to design two mechanisms based on a cellular automata-based future land-use simulation model to integrate different planning drivers into simulations. The first update mechanism considers the influence of traffic planning, while the second mechanism can model the guiding effect of planning development zones. The proposed mechanisms are applied to the Pearl River Delta region, which is one of the fastest growing areas in China. The first mechanism is validated using simulations from 2000–2013 and demonstrates that simulation accuracy is improved by the consideration of traffic planning. In the simulation from 2013–2052, the two mechanisms are implemented and yield more realistic urban spatial patterns. The simulation outcomes can be employed to identify potential urban expansion inside the master plan. The proposed methods can serve as a useful tool that assists planners in their evaluation of urban evolvement under the impact of different planning policies. 相似文献
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城市的快速扩张不断改变着土地资源的转化,带来了诸多生态环境问题。分析和模拟城市扩张的机制,并对城市未来土地利用变化的风险进行预警,利于合理调控城市的发展。本文提出了一种基于地理分区和未来用地模拟(Future Land Use Simulation,FLUS)模型的城市扩张模拟模型,用于模拟和预测复杂的土地利用变化。该模型利用多指标数据进行空间聚类,耦合地理分区结果进行城市扩张模拟。珠江三角洲2005-2015年的城市扩张模拟结果显示,分区下的模拟精度(FoM=0.2329,提高了9%)明显高于未分区,说明不同分区在土地利用转化上存在空间差异,该模型能更有效地模拟城市土地利用变化。另外,本文构建了一种城市扩张预警指标评价体系,用于评估城市扩张的警情。根据在2005-2015基础上预测的2025-2045年土地利用变化结果,对珠江三角洲城市扩张进行多尺度预警分析。综合预警结果显示该区域大部分城市至2045年城市扩张警情将达到中警和重警,其中东莞警情一直维持在重警。由此,未来需要加强对珠三角城市扩张的宏观调控,以此来缓解未来城市扩张的警情。 相似文献
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Hong Shi Xia Li Zhenzhi Yang Taohong Li Yun Ren Tingting Liu Ningdong Yang Hang Zhang Guangzhao Chen Xun Liang 《Transactions in GIS》2020,24(4):1119-1138
Previous studies on tourism land use primarily focus on the spatial distribution, and its related impacts on the environment. Here, we propose a future tourism land use simulation model for mountain vacations based on the cellular automata and Markov chain methods, having verified and simulated tourism land use in Emeishan city at a spatial resolution of 30 × 30 m using remote sensing and GIS. In addition, we introduced a tourism land use intensity index to study the spatial expansion mode of tourism land use. The results have confirmed the validity of the model and demonstrated its ability to simulate future tourism land use. The average growth rate of tourism land use from 2010 to 2015 is 33.36%, and tourism land use will rise from 1.26% of Emeishan city’s land area in 2015 to 2.95% in 2030. Tourism land use shows a spatial expansion pattern along channels from scenic spots to the urban area. The growth of tourism land use in the protected area has an increasing trend when there is no restriction on development, especially in the Eshan region. The simulation results can provide useful implications and guides for regional tourism planning and management. 相似文献