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991.
Min Cao Quanfei Shen Yanxia Wang 《International journal of geographical information science》2013,27(5):806-824
This paper presents an intelligent approach to discover transition rules for cellular automata (CA) by using cuckoo search (CS) algorithm. CS algorithm is a novel evolutionary search algorithm for solving optimization problems by simulating breeding behavior of parasitic cuckoos. Each cuckoo searches the best upper and lower thresholds for each attribute as a zone. When the zones of all attributes are connected by the operator ‘And’ and linked with a cell status value, one CS-based transition rule is formed by using the explicit expression of ‘if-then’. With two distinct advantages of efficient random walk of Lévy flights and balanced mixing, CS algorithm performs well in both local search and guaranteed global convergence. Furthermore, the CA model with transition rules derived by CS algorithm (CS-CA) has been applied to simulate the urban expansion of Nanjing City, China. The simulation produces encouraging results, in terms of numeric accuracy and spatial distribution, in agreement with the actual patterns. Preliminary results suggest that this CS approach is well suitable for discovering reliable transition rules. The model validation and comparison show that the CS-CA model gets a higher accuracy than NULL, BCO-CA, PSO-CA, and ACO-CA models. Simulation results demonstrate the feasibility and practicability of applying CS algorithm to discover transition rules of CA for simulating geographical systems. 相似文献
992.
993.
多尺度地图数据更新的一个重要途径就是通过目标匹配技术获得已更新与待更新的不同比例尺地图之间表达同一地物的候选空间目标,并对候选匹配目标对进行比较,以便获得匹配目标间的差异以及发现未匹配的目标;进而,分析判断差异是否由该目标所表达的地理要素的实际变化所导致。该文以面目标匹配为例,对多尺度地图面目标匹配对的差异驱动因素和变化类型进行分析,针对不同模式的目标匹配对提出了利用长度差异、面积差异和重叠度指标进行差异驱动因素判别、变化探测和变化类型判定的方法,并验证了该方法的有效性和实用性。 相似文献
994.
995.
Jae Min Hyun 《地球物理与天体物理流体动力学》2013,107(1-4):109-121
Abstract A study is made of the behavior of a thermally stratified fluid in a container when the non-horizontal boundaries have finite thermal conductance. The theory of Rahm and Walin is briefly recounted. Numerical solutions to the Navier-Stokes equations for a Boussinesq fluid in a cylinder, adopting a Newtonian heat flux condition at the vertical sidewall, are presented. Results on the details of flow and temperature fields are given over ranges of the Rayleigh number Ra, the container aspect ratio H, and the sidewall conductance S. As S increases, the isotherms in the meridional plane are horizontal at small radii but they diverge at large radii. This creates temperature nonuniformilies in the horizontal direction, and convective motions result. The salient features of the interior temperature profiles are captured by the theoretical model. The velocity field is characterized by two oppositely-directed circulations. As Ra or S varies, the qualitative circulation patterns remain substantially unchanged, but the magnitudes of the convective flows differ by large amounts. The effects of the externally-imposed parameters on the flow and temperature structures are examined. 相似文献
996.
Eunjin Park Wansoo Ha Wookeen Chung Changsoo Shin Dong-Joo Min 《Pure and Applied Geophysics》2013,170(12):2075-2085
The wavefield in the Laplace domain has a very small amplitude except only near the source point. In order to deal with this characteristic, the logarithmic objective function has been used in many Laplace domain inversion studies. The Laplace-domain waveform inversion using the logarithmic objective function has fewer local minima than the time- or frequency domain inversion. Recently, the power objective function was suggested as an alternative to the logarithmic objective function in the Laplace domain. Since amplitudes of wavefields are very small generally, a power <1 amplifies the wavefields especially at large offset. Therefore, the power objective function can enhance the Laplace-domain inversion results. In previous studies about synthetic datasets, it is confirmed that the inversion using a power objective function shows a similar result when compared with the inversion using a logarithmic objective function. In this paper, we apply an inversion algorithm using a power objective function to field datasets. We perform the waveform inversion using the power objective function and compare the result obtained by the logarithmic objective function. The Gulf of Mexico dataset is used for the comparison. When we use a power objective function in the inversion algorithm, it is important to choose the appropriate exponent. By testing the various exponents, we can select the range of the exponent from 5 × 10?3 to 5 × 10?8 in the Gulf of Mexico dataset. The results obtained from the power objective function with appropriate exponent are very similar to the results of the logarithmic objective function. Even though we do not get better results than the conventional method, we can confirm the possibility of applying the power objective function for field data. In addition, the power objective function shows good results in spite of little difference in the amplitude of the wavefield. Based on these results, we can expect that the power objective function will produce good results from the data with a small amplitude difference. Also, it can partially be utilized at the sections where the amplitude difference is very small. 相似文献
997.
998.
通过9片HPFL(High Performance Ferrocement Laminate)条带加固空斗墙与5片未加固的对比墙体,在低周反复荷载下试验,研究采用不同的HPFL条带加固方式对不同砌筑方式、不同强度砌筑砂浆的空斗墙在不同竖向压应力下的抗震承载力和破坏形式的影响.采用有限元计算软件AN-SYS建立HPFL条带加固空斗墙的有限元模型,分析加固条带宽度、加固面层砂浆强度、加固层钢筋网格尺寸、砌筑砂浆强度、墙体高宽比和竖向压应力等因素对加固效果的影响.研究表明:HPFL条带加固法是一种提高空斗墙抗震性能的有效方法;加固条带宽度对HPFL条带加固性能的影响最大;加固面层砂浆强度的提高,墙体的抗震承载力随之提高;加固层钢筋网格尺寸加密,对墙体承载力提高较小;不同砂浆强度砌筑的墙体,HPFL条带加固效果的发挥情况有所不同;HPFL条带圈梁构造柱式加固方式对各种高宽比和各种竖向压应力下的空斗墙都是有效的. 相似文献
999.
Although solar radiation is a crucial parameter in designing solar power devices and studying land surface processes,long-term and densely distributed observations of surface solar radiation are usually not available.This paper describes the development of a 50-year dataset of daily surface solar radiation at 716 China Meteorological Administration(CMA) stations.First,a physical model,without any local calibration,is applied to estimate the daily radiation at all 716 CMA routine stations.Then,an ANN-based(Artificial Neural Network) model is applied to extend radiation estimates to earlier periods at each of all 96 CMA radiation stations.The ANN-based model is trained with recent reliable radiation data and thus its estimate is more reliable than the physical model.Therefore,the ANN-based model is used to correct the physical model dynamically at a monthly scale.The correction generally improves the accuracy of the radiation dataset estimated by the physical model:the mean bias error(MBE) averaged over all the 96 radiation stations during 1994-2002 is reduced from 0.68 to 0.11 MJ m-2 and the root mean square error(RMSE) from 2.01 to 1.80 MJ m-2.The new radiation dataset shows superior performance over previous estimates by locally calibrated ngstr m-Prescott models.Based on the new radiation dataset,the annual mean daily solar radiation over China is 14.3 MJ m-2.The maximal seasonal mean daily solar radiation occurs in the Tibetan Plateau during summer with a value of 27.1 MJ m-2,whereas the minimal seasonal mean daily solar radiation occurs in the Sichuan Basin during winter with a value of 4.7 MJ m-2. 相似文献
1000.
安徽省东至地区金矿类型及找矿方向 总被引:4,自引:0,他引:4
安徽省东至地区位于扬子陆块北缘,跨下扬子前陆带和江南隆起带两个次级构造单元,独特的大地构造环境造就了本区有利的金矿成矿地质条件,形成多种类型的金矿床,其成因类型主要包括岩浆热液型和风化壳型,工业类型主要有破碎带蚀变岩型、含金石英脉型、微细粒浸染型及红土型。各类型金矿分类聚集,形成两个主要的金矿成矿带。沿赵家岭断层带以破碎带蚀变岩型为主,伴有含金石英脉型,中畈—戴家一带,赵家岭—杨家山一带均具较大找矿潜力,是本区金矿勘查重点地区,九华庄等地也具一定的找矿潜力;沿高坦断裂以微细粒浸染型为主,伴有破碎带蚀变岩型及红土型,查册桥地区是其重点勘查区,铜锣尖、小河等地找矿潜力也较大。 相似文献