浦东开发与上海城市地域结构优化   总被引：3，自引：1，他引：3  

何兴刚 《地理学报》1992,47(2):97-107

本文在详细分析上海城市地域结构现状、问题的基础上,探讨了造成上海城市地域结构问题的原因,认为开发浦东是上海城市地域结构优化的战略抉择。在利用浦东开发优化上海城市地域结构的进程中,必须考虑各种条件因素的制约作用,并制订出相配套的政策、措施等。  相似文献   

Anchor deployment for deep water floating offshore equipments   总被引：1，自引：0，他引：1  

O. B. Augusto  B. L. Andrade 《Ocean Engineering》2003,30(5):611-624

In this work a planning methodology for deep water anchor deployment in offshore platforms and floating production systems aiming at operational resources optimization is explored, by minimizing a multi criteria objective function. As an additional advantage provided by the proposed methodology, planning automation is achieved. Planning automation overcomes the traditional way, using a trial error basis. With it, an engineer, using an anchoring software, decides how much work wire and anchoring line must be paid out from both the floating system and the tug boat. Additionally, he decides which horizontal force must be applied to the line, trying to settle the anchor on a previously defined target on the ocean floor.  相似文献   

Vertical uplift resistance of circular plate anchors in clays under undrained condition   总被引：3，自引：0，他引：3  

Vishwas N. Khatri  Jyant Kumar   《Computers and Geotechnics》2009,36(8):1352-1359

The vertical uplift resistance of circular plate anchors, embedded horizontally in a clayey stratum whose cohesion increases linearly with depth, has been obtained under undrained ( = 0) condition. The axi-symmetric static limit analysis formulation in combination with finite elements proposed recently by the authors has been employed. The variation of the uplift factor (F_c) with changes in the embedment ratio (H/B) has been computed for several rates of increases of soil cohesion with depth. It is noted that in all the cases, the magnitude of F_c increases continuously with depth up to a certain value of H_cr/B beyond which the uplift factor becomes essentially constant. The proposed static limit analysis formulation is seen to provide acceptable results even for the two other simple chosen axi-symmetric problems.  相似文献   

Vertical uplift capacity of two interfering horizontal anchors in sand using an upper bound limit analysis     

K.M. Kouzer  Jyant Kumar 《Computers and Geotechnics》2009

The vertical uplift resistance of two interfering rigid rough strip anchors embedded horizontally in sand at shallow depths has been examined. The analysis is performed by using an upper bound theorem of limit analysis in combination with finite elements and linear programming. It is specified that both the anchors are loaded to failure simultaneously at the same magnitude of the failure load. For different clear spacing (S) between the anchors, the magnitude of the efficiency factor (ξ_γ) is determined. On account of interference, the magnitude of ξ_γ is found to reduce continuously with a decrease in the spacing between the anchors. The results from the numerical analysis were found to compare reasonably well with the available theoretical data from the literature.  相似文献   

地下洞室动态开挖的三维数值分析及优化研究   总被引：10，自引：4，他引：6  

于德海  彭建兵  臧士勇  侯克鹏 《工程地质学报》2005,13(4):502-507

针对云南锡业集团公司个旧锡矿地下采场洞室的开挖技术条件,采用非线性三维有限元法,对其动态开挖过程进行了数值模拟分析,并优化选择了地下采场洞室的开挖顺序和开挖跨距,从而得到一些有益的结论。  相似文献   

地震偏移反演成像的迭代正则化方法研究   总被引：12，自引：7，他引：5       下载免费PDF全文

王彦飞  杨长春  段秋梁 《地球物理学报》2009,52(6):1615-1624

利用伴随算子L^*,直接的偏移方法通常导致一个低分辨率或模糊的地震成像.线性化偏移反演方法需求解一个最小二乘问题.但直接的最小二乘方法的数值不稳定,为目视解译带来困难.本文建立约束正则化数学模型,研究了地震偏移反演成像问题的迭代正则化求解方法.首先对最小二乘问题施加正则化约束,接着利用梯度迭代法求解反演成像问题,特别是提出了共轭梯度方法的混合实现技巧.为了表征该方法的可实际利用性,分别对一维,二维和三维地震模型进行了数值模拟.结果表明该正则偏移反演成像方法是有效的,对于实际的地震成像问题有着良好的应用前景.  相似文献   

Calibration and uncertainty analysis of the SWAT model using Genetic Algorithms and Bayesian Model Averaging   总被引：4，自引：0，他引：4  

Xuesong Zhang  Raghavan Srinivasan  David Bosch 《Journal of Hydrology》2009,374(3-4):307-317

In this paper, the Genetic Algorithms (GA) and Bayesian Model Averaging (BMA) were used to simultaneously conduct calibration and uncertainty analysis for the Soil and Water Assessment Tool (SWAT). In this combined method, several SWAT models with different structures are first selected; next GA is used to calibrate each model using observed streamflow data; finally, BMA is applied to combine the ensemble predictions and provide uncertainty interval estimation. This method was tested in two contrasting basins, the Little River Experimental Basin in Georgia, USA, and the Yellow River Headwater Basin in China. The results obtained in the two case studies show that this combined method can provide deterministic predictions better than or comparable to the best calibrated model using GA. The 66.7% and 90% uncertainty intervals estimated by this method were analyzed. The differences between the percentage of coverage of observations and the corresponding expected coverage percentage are within 10% for both calibration and validation periods in these two test basins. This combined methodology provides a practical and flexible tool to attain reliable deterministic simulation and uncertainty analysis of SWAT.  相似文献   

Application of GA in optimization of pore network models generated by multi-cellular growth algorithms     

Saeid Jamshidi  Ramin Bozorgmehry Boozarjomehry  Mahmoud Reza Pishvaie 《Advances in water resources》2009

In pore network modeling, the void space of a rock sample is represented at the microscopic scale by a network of pores connected by throats. Construction of a reasonable representation of the geometry and topology of the pore space will lead to a reliable prediction of the properties of porous media. Recently, the theory of multi-cellular growth (or L-systems) has been used as a flexible tool for generation of pore network models which do not require any special information such as 2D SEM or 3D pore space images. In general, the networks generated by this method are irregular pore network models which are inherently closer to the complicated nature of the porous media rather than regular lattice networks. In this approach, the construction process is controlled only by the production rules that govern the development process of the network. In this study, genetic algorithm has been used to obtain the optimum values of the uncertain parameters of these production rules to build an appropriate irregular lattice network capable of the prediction of both static and hydraulic information of the target porous medium.  相似文献   

基于SOM和PSO的非监督地震相分析技术   总被引：5，自引：2，他引：3       下载免费PDF全文

张  郑晓东  李劲松  路交通  曹成寅  隋京坤 《地球物理学报》2015,58(9):3412-3423

地震相分析技术是储层预测的一种重要方法,可以用来描述有利沉积相带的分布规律.传统的地震相聚类分析方法对大数据的处理运算速度较慢,且容易陷入局部极小值,造成聚类分析的结构不准确.本文提出基于自组织神经网络(SOM)和粒子群优化方法(PSO)相结合的地震相分析技术,利用自组织神经网络能够保持原始地震数据的拓扑结构特性的特点,将大量冗余样本压缩为小样本数据,再通过粒子群的全局寻优能力改善K均值聚类的效果.理论模型和实际应用表明该方法能既有效实现数据压缩,又能提供较为准确的全局解,在地震相预测中兼顾计算效率和计算精度.  相似文献   

城市抗震设防标准的优化     

管友海  冯启民  王耀 《地震》2010,30(4):82-88

本文提出了城市抗震设防标准的优化方法, 该方法利用了建筑结构的易损性分析理论, 初始造价与设防烈度的关系, 地震设防时增加的经济投入与设防烈度的关系, 地震经济损失与设防烈度的关系等, 根据抗震设防增加的经济投入与地震经济损失之和最小的模型得到经济最优设防烈度, 并以按经济最优烈度设防时地震中的人员伤亡率小于社会可接受地震人员死亡率为限制条件, 求得最优设防烈度。  相似文献