泥石流暴发的自组织临界现象     

罗德军  艾南山  李后强 《山地学报》1995,(4)

泥石流是一种特殊的物质、能量大规模耗散的地表现象。在泥石流的形成区松散堆积物组元间的非线性作用，使系统自然地朝着临界状态演化，这种耗散动力学系统的行为特征，用自组织临界状态的概念能加以解释。泥石流规模与频率间呈幂律关系，它是自组织临界状态系统的行为标志，证明了泥石流暴发的自组织临界性．  相似文献   

LN-GDXT-Ⅱ型直流稳压电源     

孟繁强  孙宏志  吴野  张啸  马莉 《东北地震研究》2001,17(3):77-80

LN－GDXT－Ⅱ型直流稳压电源是一种比较适合于数字遥测地震台和数字地震台工作环境的在线式不间断电源。介绍了LN－GDXT－Ⅱ型直流稳压电源的工作原理，技术性能指标仪器测试及推广应用。  相似文献   

制作1:5万TM影像图的关键技术     

班艺舫  王杰生  戴昌达  胡德永 《遥感学报》1989,(4)

为了适应面广量大且需求仍在不断增长的1:5万专题调查制图的需要,我们采用数字插值放大、优化波段组合的光机复合处理技术,探索了1:5万高质量TM影像图的制作技术。本文介绍了制作1:5万高质量TM影像图的基本工艺方案及技术关键:(1)对TM图像磁带数据进行实数倍(2.28倍)双向线性插值放大,(2)在C-4500扫描仪上用50μm光点扫描获得比例尺为1:25万的潜影图像,(3)把潜影图像经显影、定影处理,再光学放大5倍,获得1:5万TM影像图。从我们结合有关任务先后在河北省南皮县、黑龙江省穆稜县和山东省莱洲湾等地区进行的试验研究看,均取得了良好效果。  相似文献   

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