A minimum-volume oriented bounding box strategy for improving the performance of urban cellular automata based on vectorization and parallel computing technology     

Chang Xia  Bin Zhang  Haijun Wang  Si Qiao  Anqi Zhang 《地理信息系统科学与遥感》2020,57(1):91-106

ABSTRACT

As an effective tool for simulating spatiotemporal urban processes in the real world, urban cellular automata (CA) models involve multiple data layers and complicated calibration algorithms, which make their computational capability become a bottleneck. Numerous approaches and techniques have been applied to the development of high-performance urban CA models, among which the integration of vectorization and parallel computing has broad application prospects due to its powerful computational ability and scalability. Unfortunately, this hybrid algorithm becomes inefficient when the axis-aligned bounding box (AABB) of study areas contains many unavailable cells. This paper presents a minimum-volume oriented bounding box (OBB) strategy to solve the above problem. Specifically, geometric transformation (i.e. translation and rotation) is applied to find the OBB of the study area before implementing the hybrid algorithm, and a set of functions are established to describe the spatial coordinate relationship between the AABB and OBB layers. Experiments conducted in this study demonstrate that the OBB strategy can further reduce the computational time of urban CA models after vectorization and parallelism. For example, when the cell size is 15 m and the neighborhood size is 3 × 3, an approximately 10-fold speedup in computational time can result from vectorization in the MATLAB environment, followed by an 18-fold speedup after implementing parallel computing in a quad-core processor and, finally, a speedup of 25-fold by further using an OBB strategy. We thus argue that OBB strategy can make the integration of vectorization and parallel computing more efficient and may provide scalable solutions for significantly improving the applicability of urban CA models.  相似文献   

花岗岩—KBF4—Na2MoO4—WO3体系的实验研究及其矿床学意义     

朱永峰  曾贻善 《岩石学报》1995,11(4):353-364

为探讨长英质岩浆作用过程中金属成矿元素的地球化学行为及其成矿意义，我们进行了常压下花岗岩－ＫＢＦ３－Ｎａ２ＭｏＯ４－ＷＯ３体系的实验研究。结果表明，高温（１２５０℃）条件下呈均一状态的花岗岩－ＫＢＦ４－ＮａＭｏＯ４－ＷＯ３体系，当温度降低时发生液态不混溶，从中分离出含矿熔体的小液滴，体系中的Ｍｏ（Ｗ）几乎全部富集在这种小液滴中。含矿熔体中极富含Ｃａ、Ｍｇ和Ｐ，而贫Ｓｉ、Ａｌ和Ｋ，Ｈ２Ｏ和Ｆ富集在含矿熔体中。此实验结果表明：长英质岩浆中液态不混溶作用的发生可以使成矿元素Ｗ和Ｍｏ富集到与硅酸盐熔体不混溶的独立的非硅酸盐熔体中。这种熔体在适当的地质条件下继续演化可形成类似镁铁质岩浆演化过程中常出现的岩浆熔离型矿床。本实验结果可能为斑岩矿床的形成机理提供一种新的解释。  相似文献   

含粗粒金矿石品位分析试样的加工制备   总被引：2，自引：1，他引：2  

王孝樽  毕慧明 《岩矿测试》1991,10(2):144-146

本文介绍了加工制备含粗粒金矿石的分析样品。对矿石含金品位低、脉石矿物硬度比较小类型的金矿全巷大样,在加工制样中筛上收>0.5mm大粒金。粒度<0.5mm矿石经缩分取样,用重选(摇床)富集粗粒金,分别检测结果,最终计算矿石总含金品位。实践表明,经本法加工试样检测结果所计算的金品位具有可靠性。  相似文献   

四川盆地南部某些子区构造发震能力的模糊聚类分析判别     

曾健  程式  王虹  王维恩 《四川地震》1992,(4)

本文在对四川盆地南部地区地震构造背景进行了特征研究的基础上,根据对类比研究区孕震构造条件分析的结果,选取12项与该地区地震发生关系密切的判别因子作为模糊聚类分析的指标,建立了该地区有震样本19个,无震样本21个。利用系统模糊聚类方法,对成都、荣县、荣昌、泸州、綦江、桐梓等子区的构造发震能力进行了模糊聚类分析判别,对这些区域的孕震震级给出了定量的结果。  相似文献   

高加索Eldjurti花岗岩体的生成环境及岩浆演化特征   总被引：4，自引：0，他引：4  

朱永峰 Sobo.  RN 《地质论评》1994,40(6):554-564

Ｅｌｄｊｕｒｔｉ岩体是俄罗斯内高加索地区阿尔卑斯造山活动晚期形成的花岗岩体。笔者研究了岩体中部由钻孔构成深达５０００ｍ的垂直剖面中岩石的岩石化学特征及岩体的生成环境和岩浆演化特征，结果表明Ｅｌｄｊｕｒｔｉ花岗岩体分异成两个岩石化学特征不同的单元，相对偏在性，岩浆分异程度较左的浅部和偏酸性，岩浆分异程度较高的深部。浆结晶分异作用使熔体中Ａｌ，Ｍｇ，Ｆｅ，Ｃａ，Ｎａ不断被消耗，Ｓｉ，Ｋ相对富集于残余熔  相似文献   

Petrological Significance of Zoned Plagioclase in Eldjurti Granite and Mafic Microgranular Enclaves,North Caucasus,Russia   总被引：5，自引：0，他引：5  

朱永峰 《中国地球化学学报》1994,13(2):142-155

Plagioclase phenocrysts from mafic enclaves and plagioclase from its host granite possess a pat-tern of complex zonation .A plagioclase phenocryst can generally be divided into three parts:an oscillatory, locally patchy zoned core (An47-19),a ring with dusty, more calcic plagioclase (An64-20) and a normally zoned rim composed of sodic plagioclase (An22-3.3). Major discontinuities in zoning coincide with resorption surfaces that are overgrown by the more calcic plagioclase.The cores of large plagioclase phenocrysts from mafic enclaves and host granite show similar zoning patterns and similar compositions, indicating their crystallization under the same conditions .Steep normal zoning of the rims of plagioclases both from host granite and mafic enclaves illustrates a drastic decrease in An content which is considered to have resulted from the continuous differentiation of hybrid magma and efficient heat loss because of the upward emplacement of the residual magma.Wide rims of plagioclases from the host granite against the discrete rims of plagioclases from mafic enclaves indicate that differentiation and cooling lasted much longer in the host granite than in the mafic enclaves.  相似文献   

Research on the microclimate characteristics and cold island effect over a reservoir in the Hexi Region   总被引：8，自引：0，他引：8  

Hu Yinqiao  Su Congxian  Zhang Yongfeng 《大气科学进展》1988,5(1):117-126

On the basis of analysis of the microclimate characteristics over a reservior in the Hexi Region, a new concept for the effect of the lake cold island is advanced. The physical mechanism and practical significance of the effect have also been analyzed.  相似文献   

三轴水泥土搅拌加固地基的应用与控制     

斯碧峰 《上海国土资源》2009,(4):4-7

文章阐述了三轴深层水泥土搅拌加固桩在浦东机场地道工程中的应用情况,并针对深层水泥土搅拌桩各个施工环节,提出了相应的质量控制措施.  相似文献   

Uplift of Northwest Margin of Tibetan Plateau: Indicated by Zircon LA ICP-MS U-Pb Dating of Conglomerate from Mazartagh, Tarim Basin     

Si Jialiang  Li Haibing  Pei Junling  Pan Jiawei 《中国地质大学学报(英文版)》2009,20(2)

Radiometric age dating of detrital zircons is highly advantageous for analysis of the depositional environment and to identify source areas. Aiming at the uplift and denudation of the surrounding ranges, LA ICP-MS U-Pb analysis has been performed on zircon grains from a conglomerate collected at the Lower Pilocene of Mazartagh, which is in the center of the Tarim basin, Xinjinng (新疆), China. A wide range of ages mainly failing into three groups was yielded: 200-500, 800-1 100, and 1 800-2 000 Ma. Zircon features principally indicate magmatic origin. According to the comparison between the analyzed zircons with those from surrounding orogenic belts, the younger grains are mainly related to the west while the older ones are to the regions more eastward. The variations might imply the W-E propagation tectonic activation and uplift of the surrounding orogenic belts. The west segment uplifted and was denuded firstly, driven by the approximate W-E height difference, upon the denudation, transportation and deposition, acting as the source of young zircons analyzed. With the eastward spreading of tectonic movement, the segment more to the east rose, the meridional relief in creased rapidly and began to control the flow direction, then more zircons joined in the Pliocene in Mazartagh. It is difficult to definitely explain the source of grains with similar values to that from the Altyn Mountain region, more detailed data and chronological ages with higher precision will be helpful for making more credible conclusion.  相似文献   

布什维尔德铂族元素矿床:铂族矿物赋存状态及其成因          下载免费PDF全文

谭娟娟  朱永峰 《地学前缘》2009,16(2):227

总结南非布什维尔德杂岩体中Merensky Reef(简称MR矿层)和Platreef(简称PR接触带)两类铂族元素矿床的矿床地质、矿化特征以及铂族元素的赋存状态。MR矿床是典型的层状铂族元素(PGE)矿床,在杂岩体东部和西部发育,PGE总含量稳定,赋存在堆晶间隙硫化物中,常以PGE硫化物的形式产出。PR接触带型矿化集中在杂岩体北段,整体上不连续,各个矿床的具体特征由于底盘岩性的多变而不同,PGE主要赋存在碲化物和砷化物等半金属化合物中,可以脱离硫化物产在硅酸盐矿物中。相关的实验研究显示,PGE在岩浆结晶过程中发生分异,Pd/Ir比值体现了硫化物的分异程度;Pd比Pt更容易被氧化以及在热液中迁移,Pt/Pd比值体现了混染和热液的作用,这些因素造成了PR接触带与MR矿层中PGE赋存状态的差异。岩浆可能在侵入之前已经达到了硫饱和,岩浆房的压力变化和岩浆通道对于PGE的富集有重要意义,热液流体可以对已经形成的PGE矿化进行改造。  相似文献