基于宽范围岩石物性约束的大地电磁和地震联合反演          下载免费PDF全文

陈晓  于鹏  邓居智  张磊  葛坤朋  王彦国 《地球物理学报》2016,59(12):4690-4700

岩石物性约束是地球物理联合反演重要的实现方式.在以往联合反演研究中,这种约束通常以点对点的映射方式出现,要求经验性的岩石物性关联是相对精确的,无形中提高了岩石物性约束应用于联合反演的条件.基于此,本文结合全局寻优的模拟退火算法,提出了宽范围岩石物性约束技术.该技术将岩石物性约束与模拟退火模型扰动、模型接受准则相结合,实现了空间对空间的映射,将电阻率和速度耦合在一起.文章以MT和地震正则化同步联合反演为例,检验了不同的先验信息条件下的宽范围岩石物性约束技术的适用性.模型试验表明:新技术容易实现,容错性高,可降低"不精确"岩石物性关联信息引入带来的风险,提高岩石物性约束应用的灵活性.  相似文献   

随钻地层测试压力响应数学模型及物理实验考察          下载免费PDF全文

马天寿  陈平 《地球物理学报》2014,57(7):2321-2333

基于随钻地层测试基本原理和渗流理论,建立了圆柱坐标系下压力下降和压力恢复阶段的压力扩散微分方程,确定出随钻地层压力测试定解问题,通过对定解问题的边界进行齐次化处理,并采用有限差分方法建立了四维空间下的显格式差分方程,以解析方法和有限差分方法分析了点源单相单测试室均质球形渗流问题,两种方法计算误差小于2.00%,检验了有限差分方法的正确性.采用有限差分方法定量分析了不同渗透率（0.1×10^-3μm²、1.0×10^-3μm²和10.0×10^-3μm²）地层下,表皮效应、储集效应、地层非均质性、抽吸速率、抽吸探头半径等因素对压力响应的影响,分析表明,这些因素对压力响应曲线的影响十分显著,主要表现在抽吸压降、压降速率、压力恢复速率、恢复时间等几个方面,而且不同渗透率地层的敏感程度差异比较大.建立了地层压力测试模拟实验平台,模拟了3种不同渗透率（108.81×10^-3μm²、16.10×10^-3μm²和4.79×10^-3μm²）地层的压力抽吸测试,并采用有限差分方法对实验进行了数值模拟.结果表明,数值模拟与实测压力响应一致性非常好,二者绝对误差小于1.60 MPa,相对误差低于5.00%（最大误差4.92%）,验证了有限差分数值方法的正确性和准确性.  相似文献   

基于混合遗传算法的斜测电离图参数反演          下载免费PDF全文

宋欢  胡耀垓  赵正予  姜春华 《地球物理学报》2014,57(3):703-714

斜向探测是获取电离层状态信息的重要手段之一,对斜测电离图的反演可以得到电离层的相关结构参数.遗传算法是一种有效的并得到普遍应用的反演方法,该算法的求解不依赖于初值的选择,可以有效地减少反演问题解的非唯一性,但也存在“过早收敛”和局部搜索能力差等缺陷,从而导致反演精度下降,影响反演结果的可靠性.本文提出将基于模拟退火的混合遗传算法应用到斜测电离图的参数反演中,该算法不仅把握总体能力强,且具有较强的局部搜索能力,是遗传算法和模拟退火算法的优势互补.为了验证该算法反演结果的可靠性和稳定性,首先分别采用遗传算法、模拟退火算法和混合遗传算法对合成的电离图进行反演,反演参数包括临界频率,最大电子浓度和半厚度.通过对三种算法反演结果的对比,得出混合遗传算法的反演结果最接近真实值,需要的迭代次数也远远小于其他两种算法;通过改变种群大小和总迭代次数来判断参数值的改变对三种算法反演结果的影响,得出混合遗传算法有效地降低了参数的选取对反演结果的影响.然后用这三种反演算法对实测电离图进行反演,并将它们的反演结果与斜测链路中点的实际垂测数据进行比较,结果显示混合遗传算法84.62%的反演结果可以控制在误差范围之内,高于遗传算法（76.93%）和模拟退火算法（65.38%）.这些都表明了混合遗传算法的反演结果具有较强的可靠性,在反演的寻优能力和稳定性上要明显优于遗传算法和模拟退火算法,对实测电离层图的反演具有很强的借鉴意义和应用价值.  相似文献   

基于Voronoi邻近的物流车辆路径快速优化算法     

涂伟  方志祥  李清泉  鲁仕维 《地球信息科学学报》2012,14(6):781-787

 现代物流业需要快速高效并智能化制定物流运输方案。传统路径优化方法适合处理中小规模的车辆路径问题,计算时间较长,方案质量较低,故需发展短时间内能提供高质量路径方案的启发式算法。针对大规模物流车辆路径优化,本文提出了一种Voronoi邻近的快速优化方法。该方法先创建初始解,而后进行迭代优化。初始解创建利用Voronoi邻近关系,顾及车辆容量约束,自底向上进行客户点空间聚类,将问题降维;采用最廉价插入算法安排聚类内部路径,生成性质良好的初始解。迭代优化在客户点Voronoi邻近内进行有效的局部搜索,利用模拟退火机制接受较差解,从而跳出局部最优,不断提高解的质量。本文利用模拟生成的北京市大规模车辆路径问题进行实验,结果表明:本文算法能够在4500s内优化客户点高达12 000个物流车辆路径问题,计算时间较短,解的质量优良,算法性能稳定。本文与其他算法比较,能在较短时间内提供高质量车辆路径方案,适用于大规模物流车辆路径的优化。  相似文献   

Importance of hydrogeological conditions during formation of the karstic bauxite deposits,Central Guizhou Province,Southwest China: A case study at Lindai deposit     

《Ore Geology Reviews》2017

Karstic bauxite deposits are widespread in Central Guizhou Province, SW China, and high-grade ores are frequently sandwiched with overlying coal and underlying iron-rich layers and form a special “coal–bauxite–iron” structure. The Lindai deposit, which is one of the most representative karstic bauxite deposits in Central Guizhou Province, was selected as a case study. Based on textural features and iron abundances, bauxite ores in the Lindai deposit are divided into three types of ores, i.e., clastic, compact, and high-iron. The bauxite ores primarily comprise diaspore, boehmite, kaolinite, illite, and hematite with minor quartz, smectite, pyrite, zircon, rutile, anatase, and feldspar. The Al₂O₃ (53–76.8 wt.%) is the main chemical contents of the bauxite ore samples in the Lindai district, followed by SiO₂, Fe₂O₃, TiO₂, CaO, MgO, S, and P etc. Our geological data on the Lindai deposit indicated that the ore-bearing rock series and its underlying stratum have similar rare earth elements distribution pattern and similar Y/Ho, Zr/Hf, and Eu/Eu¹ values; additionally, all ore-bearing rock samples are rich in MgO (range from 0.16 wt.% to 0.68 wt.%), and the plots of the dolomites and laterites lie almost on or close to the weathering line fit by the Al-bearing rocks in Zr vs. Hf and Nb vs. Ta diagrams; suggesting that the underlying Middle Cambrian Shilengshui Formation dolomite is the parent rock of bauxite resources in the Lindai district.Simulated weathering experiments on the modern laterite from the Shilengshui Formation dolomite in the Lindai bauxite deposit show that hydrogeological conditions are important for karstic bauxite formation: Si is most likely to migrate, its migration rate is several magnitudes higher than those of Al and Fe under natural conditions; the reducing inorganic acid condition is the most conducive to Al enrichment and Si removal; Fe does not migrate easily in groundwater, Al enrichment and Fe removal can occur only in acidic and reducing conditions with the presence of organic matter.The geological and experimental studies show that “coal–bauxite–iron” structure in Lindai deposit is formed under certain hydrogeological conditions, i.e., since lateritic bauxite or Al-rich laterite deposited upon the semi-closed karst depressions, Si can be continuously removed out under neutral/acidic groundwater conditions; the coal/carbonaceous rock overlying the bauxitic materials were easily oxidized to produce acidic (H₂S, H₂SO₄, etc.) and reductant groundwater with organic materials that percolated downward, resulting in enrichment of Al in underlying bauxite; it also reduced Fe³⁺ to its easily migrating form Fe²⁺, moving downward to near the basal carbonate culminated in precipitating of ferruginous (FeS₂, FeCO₃, etc.) strata of the “coal–bauxite–iron” structure. Thus, the bauxitic materials experienced Al enrichment and Si and Fe removal under above certain hydrogeological conditions forming the high-quality bauxite.  相似文献   

基于混合优化算法的MT阻抗张量畸变分解方法          下载免费PDF全文

李洋  于鹏  张罗磊  王家林  吴健生 《地球物理学报》2010,53(8):1924-1930

在前人研究基础上,对Groom-Bailey(GB)张量分解畸变因子和区域阻抗的求解方法进行了改进.首先,通过Swift旋转与GB分解的扭变和剪切矩阵的求逆变换,利用变换后区域阻抗主对角元素为0的条件获得关于扭变因子和剪切因子的超定方程组,采用模拟退火全局优化算法进行求解.其次,由得到的扭变因子和剪切因子,结合Swift旋转确定的走向角和区域阻抗元素的估计,作为非线性最小二乘局部优化算法的初始值,对GB分解定义式的超定方程组进行求解,得到各畸变参数和区域阻抗的解.通过模型试验验证了方法的正确,对方法的稳定性进行了比较与评价,并通过与已有结果的对比和实际资料的应用,表明了方法实际应用的效果.  相似文献   

元启发式搜索策略在构造模糊分类系统中的应用     

郑晓月 《成都信息工程学院学报》2010,25(1):26-29

论述了使用模拟退火元启发式搜索策略构造模糊分类系统的过程,目的是利用模拟退火原理研制一种精确的模糊分类器,改善与分类问题有关的搜索空间探索与发掘的性能,找到模糊if-then规则的优化集。算法可以从输入数据集中抽取精确的模糊分类规则,并在若干不同预定义类中将其应用于对新数据实例的分类。  相似文献   

改进的模拟退火遗传算法在地下水管理中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

李平  卢文喜  靳孟贵 《水文地质工程地质》2011,38(3):9-13

对于高度非线性、非凸的地下水管理模型,传统优化方法难以找到全局最优解。本文采用模拟退火遗传算法求解地下水管理模型,并从三个方面对算法进行改进:引入小生境技术,采用自适应交叉和变异概率,在选择过程中采用最优保存策略,从而提高算法的全局寻优能力和收敛速度。采用惩罚函数法处理约束条件。用Fortran 90语言编制了计算程序,并通过Schaffer测试函数验证了该算法不仅具有强大的全局寻优能力和局部搜索能力,而且具有较快的收敛速度和较高的优化精度。将该算法应用到某研究区地下水管理中,取得了较好的效果。  相似文献   

Effects of biological soil crusts on water infiltration and evaporation Yanchi Ningxia,Maowusu Desert,China   总被引：4，自引：0，他引：4  

《国际泥沙研究》2016,(4):311-323

Biological soil crusts serve as a vanguard for improving the ecological environment in arid, semi-arid desertification areas. It is a good indicator of the level of improvement which the local ecological environment is undertaking. In desert areas, water condition is a key factor of improving the ecological environment. As a first layer protection, biological crusts play an important role in local vegetation succession due to their abilities to conserve and maintain moisture. Using Maowusu desert in Yanchi of Ningxia province as an example, after three years of research, this paper chooses three kinds of biological crusts including lichen, moss and cyanobacterial which are under the cover of Artemisia ordosica as research objects. The results of this study indicate that, the closer biological crusts are to Artemisia ordosica vegetation, the thicker they become. In the same position of Artemisia ordosica vegetation, the thickness of moss crusts is the highest, followed by lichen crusts, and the thickness of cyanobacterial crusts is the lowest. Biological soil crusts coverage protects the natural water content of soil layers from 0 to 5 cm. Also, it effects falling water to infiltrate deeper, and cannot prevent the surface water content from evaporating effectively. The effect of biological crusts blocking water infiltration decreases with the increase of rainfall. At the same rainfall level, moss crusts provide the strongest water infiltration blockage, followed by lichen crusts and cyanobacterial crusts. With the increase of rainfall, the depth of water infiltration increases. At the same rainfall level, the relationship of water infiltration depth is as follows: cyanobacterial crusts 4 lichen crusts 4 moss crusts. With the increase of biological crusts thickness, they blocking water infiltration capacity is stronger, and the depth of water infiltration is smaller. Analysis on the characteristic of simulated rainfall process on biological crusts shows that sandy land can be fixed by applying appropriate artificial biological crusts to build a sustainable forest pro-tection system and to create a stable ecosystem in desertification area.  相似文献   

山区谷底沉陷预测模型及其参数反演     

郭庆彪  郭广礼  吕鑫  陈涛  王金涛 《岩土力学》2016,37(5):1351-1356

我国西部地区地势复杂,沟壑纵横,地下开采极易导致边坡失稳,引发采动滑坡。在地下采动沉降与滑坡体挤压上升的叠加影响下,谷底区域地表沉降值明显小于类似地质采矿条件下的平原地区。为准确预测山区谷底区域地表沉降值,基于简支梁的弹性变形理论,并借助概率密度函数建立了山区谷底区域地表沉陷预计修正模型,明确模型参数物理意义及其取值方法。依据修正模型,以实测值和预测值之差平方和最小为原则构建适应值函数,基于模拟退火粒子群算法提出新的模型参数反演方法,借助MATLAB语言编制了相应的参数反演程序。最后将研究成果应用于山西某矿,得到谷底区域预测结果中误差为73 mm,与实测值基本一致,取得了较好的工程实践效果。  相似文献