General coupling extended multiscale FEM for elasto‐plastic consolidation analysis of heterogeneous saturated porous media          下载免费PDF全文

Hongwu Zhang  Mengkai Lu  Yonggang Zheng  Sheng Zhang 《国际地质力学数值与分析法杂志》2015,39(1):63-95

This paper presents a general coupling extended multiscale FEM (GCEMs) for solving the coupling problem of elasto‐plastic consolidation of heterogeneous saturated porous media. In the GCEMs, the numerical multiscale base functions for the solid skeleton and fluid phase of the coupling system are all constructed on the basis of the equivalent stiffness matrix of the unit cell, which not only contain the interaction between the solid and fluid phases but also consider the time effect. Furthermore, in order to improve the computational accuracy for two‐dimensional problems, a multi‐node coarse element strategy for the GCEMs is proposed, and a two‐scale iteration algorithm for the elasto‐plastic consolidation analysis is developed. Some one‐dimensional and two‐dimensional homogeneous and heterogeneous numerical examples are carried out to validate the proposed method through the comparison with the coupling multiscale FEM and standard FEM. Numerical results show that the newly developed GCEMs can almost preserve the same convergent property as the standard FEM and also possesses the advantages of high computational efficiency. In addition, the GCEMs can be easily applied to other coupling multifield and multiphase transient problems. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Coupled formulation and algorithms for the simulation of non‐planar three‐dimensional hydraulic fractures using the generalized finite element method          下载免费PDF全文

P. Gupta  C. A. Duarte 《国际地质力学数值与分析法杂志》2016,40(10):1402-1437

This paper presents a coupled hydro‐mechanical formulation for the simulation of non‐planar three‐dimensional hydraulic fractures. Deformation in the rock is modeled using linear elasticity, and the lubrication theory is adopted for the fluid flow in the fracture. The governing equations of the fluid flow and elasticity and the subsequent discretization are fully coupled. A Generalized/eXtended Finite Element Method (G/XFEM) is adopted for the discretization of the coupled system of equations. A Newton–Raphson method is used to solve the resulting system of nonlinear equations. A discretization strategy for the fluid flow problem on non‐planar three‐dimensional surfaces and a computationally efficient strategy for handling time integration combined with mesh adaptivity are also presented. Several three‐dimensional numerical verification examples are solved. The examples illustrate the generality and accuracy of the proposed coupled formulation and discretization strategies. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Relational Hubs for Collaborative Landscape Stewardship     

Jessica Cockburn  Georgina Cundill  Sheona Shackleton  Ayanda Cele  Susanna Francina Cornelius  Vaughan Koopman 《社会与自然资源》2020,33(5):681-693

Abstract

Landscape stewardship is considered an important place-based approach to addressing sustainability challenges. Working at landscape-level requires collaboration between diverse landscape stakeholders. In this study, we partnered with local stewardship practitioners across six cases in South Africa to investigate how they facilitate collaboration towards social-ecological sustainability outcomes. We found that practitioners facilitate collaboration among stakeholders by operating as relational hubs in the landscape. Through these hubs, they build new inter-personal relationships among stakeholders, creating social networks which enable stewardship practice. The hubs deepen human-nature relationships by creating enabling conditions for stewards to put stewardship ethics into action. Drawing on insights from these cases, we call for a relational approach to landscape stewardship which focuses on human-to-human and human-to-nature relationships. Moreover, we argue that landscape stewardship initiatives need to re-focus stewardship on stewards, recognizing them as key agents of change in addressing the conflict between agriculture and conservation inherent in many landscapes.  相似文献   

High‐ and low‐flow variations in annual runoff and their response to climate change in the headstreams of the Tarim River,Xinjiang, China     

Hongbo Ling  Hailiang Xu  Jinyi Fu 《水文研究》2013,27(7):975-988

Based on the hydrological and meteorological data recorded for the northern and southern headstreams of the Tarim River over the last 50 years, this paper analyses the variation characteristics of high‐flow and low‐flow indexes of annual runoff, air temperature and precipitation using a non‐parametric test. Additionally, this paper also studies the correlations between these three time series on multiple time scales for both northern and southern headstreams employing wavelet analysis. The results show the following: (i) the annual runoff and air temperature had significant increasing trends, whereas precipitation had a non‐significant increasing trend for the northern and southern headstreams. (ii) Abrupt changes appeared in precipitation in the north and south in 1990 and 1986, as well as in high‐flow and low‐flow indexes of annual runoff in 1993 and in air temperature in 1996. (iii) In the case of the northern headstreams, there was significant periodicity of 6 years in both high‐flow and low‐flow indexes and air temperature and of 3 and 8 years in precipitation. In the case of the southern headstreams, there was significant periodicity of 3 and 9 years in high‐flow and low‐flow indexes, 5 years in air temperature, and 5 and 8 years in precipitation. (iv) The high‐flow and low‐flow indexes in the headstreams of the Tarim River are closely related to the air temperature and precipitation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Tracking a Governance Transition: Identifying and Measuring Indicators of Social Forestry on the Willamette National Forest     

Jesse Abrams  Heidi Huber-Stearns  Hannah Gosnell  Anna Santo  Stacie Duffey  Cassandra Moseley 《社会与自然资源》2020,33(4):504-523

Abstract

National Forests in the United States have undergone a spatially and temporally uneven governance transition in response to social and economic pressures and contemporary policy changes, with many national forest units moving from a wholly government-led “dominant federal” model to a more collaborative “social forestry” model in which nonfederal actors have greater influence and authority. Here we report on an effort to develop a suite of indicators designed to capture some of the most tangible elements of a transition from dominant federal to social forestry modes of governance. We pilot test these data on the Willamette National Forest using data from a variety of sources internal and external to the USDA Forest Service. We assess the suitability of these indicators for tracking governance transitions and discuss their applicability to other national forest units nationwide.  相似文献   

Evaluation of multi‐use stormwater detention basins for improved urban watershed management          下载免费PDF全文

Daeryong Park  Sukhwan Jang  Larry A. Roesner 《水文研究》2014,28(3):1104-1113

Detention basins are used to capture postdevelopment runoff and control the peak discharge of the outflow using orifices and weirs. The use of detention basins is typical practice in the construction of new developments on the fringe of existing urban areas, such as the Ulsan–Hwabong district in the city of Ulsan, South Korea. In this study, the required volume and flooding area of a detention basin was determined to control development outflow peaks for 2‐year, 10‐year, and 100‐year design storms with type II rainfall distributions as characterized by the US Department of Agriculture's Soil Conservation Service method. The rainfall–runoff simulation model used was the US Environmental Protection Agency's Storm Water Management Model (EPA‐SWMM) 5, which is the latest version of the software, updated for Windows. We designed three cases of detention basins multi‐staged by 2‐year, 10‐year, and 100‐year design storms and verified the designs with the application of 49 years (1961–2009) of hourly historical rainfall data. The three detention basin designs were compared in terms of the total construction and land costs as well as the benefits associated with recreational facilities or parking lot use. As a result, the design sizes of the detention basins are slightly greater than the actual sizes needed based on the historical rainfall application. Multi‐use detention basins (MDBs) based on 2‐year and 10‐year design storms were found to yield 37.4% and 22.8% benefits, respectively, for recreational facility use compared with detention basins without multi‐use space, and the results also indicate that benefits accrue after 6.5 years for parking lot use. The results of this study suggest that an MDB based on a 2‐year design storm is the most cost‐effective design among the three cases considered for Ulsan, South Korea. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

强对流天气综合监测业务系统建设   总被引：12，自引：4，他引：8  

郑永光  林隐静  朱文剑  蓝渝  唐文苑  张小玲  毛冬艳  周庆亮  张志刚 《气象》2013,39(2):234-240

强对流天气监测是其预报的基础.国家气象中心强天气预报中心利用多源观测资料(常规和非常规资料)建设了强对流天气综合监测业务系统.强对流天气的监测对象包括积云、地面高温、雷暴、地闪、冰雹、龙卷、大风、雷暴大风、短时强降水、雷暴反射率因子、对流风暴(基于雷达资料)、深对流云及中尺度对流系统(Mesoscale Convective Systems,MCS,基于静止卫星红外1通道资料)等不同时段的分布.发展的监测技术主要包括自动站资料质量控制技术、强对流信息提取和统计技术、直角坐标交叉相关雷达回波追踪(Cartesian Tracking Radar Echoes by Correlation,CTREC)技术、雷暴识别追踪分析和临近预报(Thunderstorm Identification Tracking Analysis and Nowcasting,TITAN)技术、深对流云识别技术、中尺度对流系统识别和追踪技术,以及闪电密度监测技术等.强对流天气监测系统自动定时运行,其输出数据与MICAPS业务平台完全兼容.该监测系统在国家气象中心的强对流天气预报业务中发挥了重要作用.  相似文献   

基于多源遥感的莺歌海滨岸环境特征分析     

乔纪纲  艾彬  邹春洋 《热带地理》2011,31(5)

采用综合多源遥感方法提取地表信息,结合文献资料和实地调查数据探讨莺歌海滨岸带地面要素的分布特征及其相互关系.主要讨论了综合激光雷达(LiDAR)、极化合成孔径雷达(SAR)、光学和光谱遥感数据进行地表信息提取的适用方法,包括建立精细潮位线模型、近岸微地貌模型,并进行沙化土地、植被、湿地的提取与分类;分析了莺歌海滨岸区的海岸形态、土地退化、湿地与植被分布以及自然景观结构的特征.研究表明,综合遥感方法能有效地支持地表环境特征提取;研究区内滩涂和湿地资源利用不合理;存在较高的土地退化风险;湿地开发与盐场生产活动为人地关系的核心矛盾.最后提出了相关的综合治理建议.  相似文献   

宁夏灾害性天气短时临近监测预警平台简介     

马金仁  纪晓玲  邵建  贾宏元  穆建华 《干旱气象》2013,(3):616-621

根据完善气象预报预测系统的规划和需求,在继承和改进短时临近预报业务工作多年成果的基础上,宁夏气象台建立了灾害性天气短时临近监测预警平台。该平台设计为B／S和C／S架构有机结合,由数据运算程序集、数据库和网站3个部分交互协作的业务系统。本文从平台设计思路、结构特点、各模块主要功能等对宁夏灾害性天气短时临近监测预警平台作一简单介绍。该平台根据宁夏气象业务发展和防灾减灾实际需要研发,评估、优化、更新、整合了已有研究成果,融合多种探测资料与方法,突出短时临近灾害性天气实时监测预警和多模式预报产品检验评估与综合集成预报技术,建成以集成预报、国家指导预报、中尺度数值预报等定量化预报产品为基础,集“实时监测预警与综合分析、强对流灾害天气预报方法、检验评估与集成预报、预报预警快速制作分发”等为一体的业务平台。  相似文献   

城市土地利用空间优化配置的多智能体系统与微粒群集成优化算法     

张鸿辉  曾永年  尹长林  喻定权 《武汉大学学报(信息科学版)》2011,(8):1003-1007

在多目标约束下,构建了应用于城市土地利用空间优化配置的多智能体系统与微粒群集成优化算法,并以长株潭城市群的核心区域为例,开展了基于该算法的城市土地利用空间优化配置应用研究。研究结果表明,集成优化算法的Agent平均适应值和运行效率分别较微粒群优化和标准遗传算法得到了大幅度提高,从而证明了算法的可行性与先进性。  相似文献