岱海湿地生态环境变化的气候影响分析   总被引：1，自引：0，他引：1  

陈海英  付旭峰  赵慧珍  王贵生 《内蒙古气象》2011,(6):14-17

文章针对岱海湖水恶化、湖盆萎缩,流域水土流失严重,湿地面积锐减、功能退化等生态环境问题,着重在气候条件方面对岱海湿地变化产生的一些可能影响作了详细分析与说明,并提出相应防治对策。  相似文献   

A naturally efficient numerical technique for porous convection stability with non‐trivial boundary conditions     

L. E. Payne  B. Straughan 《国际地质力学数值与分析法杂志》2000,24(10):815-836

A highly efficient numerical technique is presented for solving eigenvalue problems which arise in complicated convection — instability studies in porous media. The differential equations are written as a system of ‘natural’ variables which are suggested by the way the boundary conditions arise. The method easily gives high resolution in boundary layers, yields all the eigenvalues and eigenfunctions, deals with complex coefficients, and can handle spatially dependent coefficients in a very efficient manner. The numerical technique is motivated by the practical problem of salinization in porous sands in arid zones as is beautifully modelled by Gilman and Bear. Since the salinization study of Gilman and Bear is a prototype for the field of convective motion in unsaturated porous soils and this field is one which is increasingly occupying geotechnical attention, we believe the numerical method presented here has much potential. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

NLS问题的不适定性及正则化解算方法     

唐利民 《测绘科学》2010,35(6):103-104,235

本文进一步完善定义了NLS问题的两种不适定性,对产生这两种不适定问题的现象进行了分析。借助于正则化理论,通过添加稳定泛函,结合高斯-牛顿法,构造了不适定NLS问题的正则化高斯-牛顿法求解公式;解决了普通高斯-牛顿法在迭代过程中其Jacobian矩阵是秩亏或者严重病态导致的不能收敛的问题;给出了非线性秩亏自由网平差的正则化高斯-牛顿法步骤;以几个经典NLS问题为例进行了数值实验,说明了本文所提方法的适用性。  相似文献   

浅谈基层国土资源所档案管理存在的问题及对策     

车莉莉 《山东地质》2011,(6):64-66

当前基层国土资源所档案管理存在资料收集不完整、交接不及时、设施简陋等问题,影响了国土资源档案作用的发挥。必须从建立有效工作机制入手,从档案的收集、转交、管理、利用各环节采取切实有效的对策,充分发挥档案对推进国土资源管理的作用。  相似文献   

LINEAR RAINFALL–RUNOFF SYSTEM IDENTIFICATION WITH RAMIFICATIONS FOR MODELLING CATCHMENT PROCESSES     

C. R. DIETRICH 《水文研究》1996,10(6):893-902

The convolution assumption between excess rainfall and runoff provides a framework in which catchment runoff can be predicted with reasonable accuracy and moderate computational cost. Associated with it, the deconvolution problem of estimating unitgraph ordinates from rainfall–runoff events involves a matrix with a particularly simple structure. This matrix structure is used here as a basis on which the ill-posed nature of deconvolution is analysed. As a result, based on a simple transform of the excess rainfall data, a very simple criterion is derived to test the degree to which deconvolution may yield a unit hydrograph estimate displaying spurious oscillations of large magnitude. This has practical implications as the solution to an ill-posed problem can be very sensitive to errors in the model and the data and therefore may need to be stabilized. Illustration of these issues is provided using published rainfall–runoff data.  相似文献   

土壤粗有机质的研究进展   总被引：2，自引：0，他引：2  

梁爱珍  张晓平  杨学明  方华军 《地理科学进展》2006,25(3):128-136

土壤粗有机质是土壤中较为活跃的组分, 其密度组分对土壤有机质总矿化量有着重要贡 献, 可以作为评价管理措施转变引起土壤有机质短期变化的敏感性指标。分别介绍了按照不同的 物理分组方法划分的土壤有机质各物理组分的概念、土壤粗有机质及其分离方法, 探讨了影响土 壤粗有机质数量的主要因素( 管理措施、土地利用方式、土壤质地和气候条件) 和当前在研究土壤 粗有机质过程中存在的问题: ( 1) 各影响因素引起的土壤有机质变化的机制还不确定; ( 2) 土壤粗 有机质的分离方法还有待深入研究; ( 3) 粗有机质对土壤有机氮矿化的贡献认识还存在分歧。指 出探求更好的土壤粗有机质的分离方法和粗有机质对各影响因素的响应机制, 揭示土壤粗有机 质对土壤氮矿化的贡献是今后的主要研究方向。  相似文献   

昌邑市生态地质环境保护对策   总被引：1，自引：1，他引：0  

王岳林  韩树红  张作礼 《山东国土资源》2009,25(9):37-40

昌邑市位于山东省北部莱州湾南岸,南北狭长,南部为丘陵,中部和北部为平原,潍河纵贯南北。在查明市域内各种生态环境地质问题的基础上,将昌邑市划分为4个生态地质环境保护区和1个生态地质环境保护带,针对各区存在的主要问题,提出了不同的保护对策。  相似文献   

南四湖湿地地质环境评价及保护措施浅析          下载免费PDF全文

王义生  贾德旺  岳跃华  肖华  王学森 《山东国土资源》2007,23(1):41-44

南四湖是南水北调东线工程的重要调蓄枢纽,目前湿地环境地质问题较多,主要表现为湿地面积变化大、水环境污染、水资源开采过度、湖区淤积严重、湖泊沼泽化、采空塌陷等,危胁着调水工程的顺利实施。针对湿地特征及问题成因,进行单元格剖分后建立了一套完整的评价体系,第一层将其分解为水环境、土壤环境、南四湖表层底泥重金属污染及南四湖湿地地质环境问题4个要素层;第二层再把湿地环境地质问题要素分解成若干个次要素,逐层评价后采用综合指数法求出指数值,将湿地地质环境质量划分为良好区、较好区、较差区。提出了划分渔业生产保护区、调整水生植物布局、定期泥沙清淤及建设人工湿地水质净化工程和人工湿地河道走廊工程等保护措施。  相似文献   

Undersea Buried Pipeline Reconstruction Based on the Level Set and Inverse Multiquadric Regularization Method     

SHANG Wenjing  XUE Wei  XU Yidong  MAKAROV Sergey B.  LI Yingsong 《中国海洋大学学报(英文版)》2022,21(1):101-112

The electric inversion technique reconstructs the subsurface medium distribution from acquired data. On the basis of electric inversion, objects buried under the earth or seabed, such as pipelines and unexploded ordnance, are detected and located in a contactless manner. However, the process of accurately reconstructing the shape of the target object is challenging because electric inversion is a nonlinear and ill-posed problem. In this work, we present an inverse multiquadric (IMQ) regularization method based on the level set function for reconstructing buried pipelines. In the case of locating underwater objects, the unknown inversion area is split into two parts, the background and the pipeline with known conductivity. The geometry of the pipeline is represented based on the level set function for achieving a noiseless inversion image. To obtain a binary image, the IMQ is used as the regularization term, which 'pushes' the level set function away from 0. We also provide an appropriate method to select the bandwidth and regularization pa-rameters for the IMQ regularization term, resulting in reconstructed images with sharp edges. The simulation results and analysis show that the proposed method performs better than classical inversion methods.  相似文献   

重力式码头过大位移和不均匀沉降质量通病防治     

李宏升  张刚  方耀卿 《海岸工程》2009,28(3):49-57

结合烟台港三突堤集装箱码头工程施工，对重力式码头过大位移和不均匀沉降的现象、成因和危害进行了分析总结，并提出防治措施，取得了明显效果。  相似文献