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   

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   

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   

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   

黄河三角洲滩涂区海堤护岸结构方案优化实证研究          下载免费PDF全文

刘建波  翟有经 《海洋开发与管理》2017,34(3):92-98

海堤护岸是抵御和减轻风暴潮灾害的根本措施,是从根本上消除风暴潮对沿岸人民生命财产安全威胁的最有效措施之一。黄河三角洲沿海滩涂广阔平坦,多为沙质和淤泥质,沟壑交错,海堤护岸的建设量大面广,所以对区域内海堤护岸的建设方案进行比较优化,更显得十分必要。文章通过具体的工程案例,阐述了建于黄河三角洲滩涂区的海堤护岸结构方案的比选与优化步骤与方法,这无疑对建于滨海滩涂区的海堤护岸的方案优化具有直接的参考与借鉴意义。  相似文献   

A dynamic programming model for optimal planning of aquifer storage and recovery facility operations   总被引：3，自引：0，他引：3  

V. Uddameri 《Environmental Geology》2007,51(6):953-962

Aquifer storage recovery (ASR) is an innovative technology with the potential to augment dwindling water resources in regions experiencing rapid growth and development. Planning and design of ASR systems requires quantifying how much water should be stored and appropriate times for storage and withdrawals within a planning period. A monthly scale planning model has been developed in this study to derive optimal (least cost) long-term policies for operating ASR systems and is solved using a recursive deterministic dynamic programming approach. The outputs of the model include annual costs of operation, the amount of water to be imported each month as well as the schedule for storage and extraction. A case study modeled after a proposed ASR system for Mustang Island and Padre Island service areas of the city of Corpus Christi is used to illustrate the utility of the developed model. The results indicate that for the assumed baseline demands, the ASR system is to be kept operational for a period of 4 months starting from May through August. Model sensitivity analysis indicated that increased seasonal shortages can be met using ASR with little additional costs. For the assumed cost structure, a 16% shortage increased the costs by 1.6%. However, the operation time of ASR increased from 4 to 8 months. The developed dynamic programming model is a useful tool to assess the feasibility of evaluating the use of ASR systems during regional-scale water resources planning endeavors.  相似文献   

长输管道勘测工作中的问题分析及对策     

沙俊飞  李从军 《现代测绘》2006,29(3):47-48

本文对通过对仪长管道线路测量勘察、水文地质、河流、冲沟穿跨越勘测存在的问题进行了分析,并提出了相应的改进措施和建议,旨在加强对管道建设勘测阶段的管理,提高勘测水平,达到优化设计和投资的目的。  相似文献   

模糊评判在露天转地下矿山的矿房结构参数优化中的应用   总被引：1，自引：0，他引：1  

韩现民  李晓  杜国栋 《工程地质学报》2006,14(5):654-660

模糊评判法能较好地解决方案选择的问题。本文针对石人沟铁矿露天转地下矿山过渡期开采期间,矿山地下开采带来的露天边坡、地下采场稳定性问题,通过数值模拟,得到地下第一中段开采时地下采场和边坡的应力、应变数值,并结合矿块的采切比、矿块回采率经济指标,运用模糊数学的方法,建立了考虑经济效益的稳定性模糊评判模型。通过合理确定评价指标的隶属度函数和利用二元排序法构造判断矩阵确定各评价指标的权重,对9种方案进行了综合评判,确定了最优方案,选出了合理的矿房结构参数,既可保证矿山的安全生产,又可保证矿山经济效益。  相似文献   

Multi-objective stochastic-structural-optimization of shape-memory-alloy assisted pure-friction bearing for isolating building against random earthquakes     

《Soil Dynamics and Earthquake Engineering》2013

The optimal stochastic performance of pure friction system supplemented with SMA-restrainer (SMA-PF) is presented based on a framework of multi-objective optimization. The evaluation of system response for this is based on nonlinear random vibration analysis. The optimizing design variables are based on two mutually conflicting objectives, involving maximizing the isolation efficiency as well as isolator displacement. The proposed optimal design, thus, not only maximizes the isolation efficiency but also impose due consideration to the bearing displacement. The optimal bearing is shown to substantially reduce the bearing displacement with nominal sacrifice in isolation efficiency. Comparison of the multi-objective Pareto fronts reveals much facilitated trade-off among the mutually conflicting objectives in SMA-PF than in PF system. The viability of the optimal performance is further verified under recorded ground motions, which is observed to be in parity to the stochastic response behavior. The reduction in the residual bearing displacement is also observed.  相似文献   

Combined loading of caisson foundations in cohesive soil: Finite element versus Winkler modeling     

《Computers and Geotechnics》2014

The undrained response of massive caisson foundations to combined horizontal, vertical and moment loading is parametrically investigated through a series of 3D finite element analyses. The parameters are: (a) the embedment ratio (D/B), (b) the factor of safety against initial vertical loading (FS_V) and (c) the ratio of the overturning moment to the horizontal force applied at the top of the caisson (M/Q). Emphasis is given on: (i) the identification of all possible failure mechanisms in M–Q–N space, (ii) the developed stress distributions along the caisson walls for various load levels up to complete failure conditions. The results are then used as a feedback for calibrating the parameters of a generalized four-type spring model, originally proposed by Gerolymos and Gazetas (2006), through a genetic algorithm-based optimization procedure. The predictions of the Winkler model compare very well with the FE results, not only at the local response level (in terms of stress distributions along the caisson shafts), but at a global response level (in terms of force–displacement curves and M–Q–N failure envelopes at the top of the caisson) as well. Contrary to established lateral soil resistance theories, it is shown that both the ultimate horizontal soil reaction and resisting moment per unit depth do not solely depend on the strength properties of soil and geometry of the caisson but are also functions of the applied load ratio M/Q and initial soil yielding due to vertical loading. Interesting conclusions are also drawn regarding the transition from the elastic to the ultimate limit state (hardening). Quantifying through analytical expressions the contribution of each of the two basic lateral resisting mechanisms to the response of the caisson, a classification method for embedded foundations is then proposed. The capabilities of the Winkler model are further demonstrated through comparison with FE analysis of the caisson cyclic lateral response.  相似文献