不锈钢表面纳米SnO2/TiO2复合薄膜制备及防腐蚀性能     

王爱萍  周爱华 《中国海洋大学学报(自然科学版)》2020,50(3):81-87

采用溶胶凝胶法在不锈钢基体(304ss)上制备叠层式纳米SnO2/TiO2复合薄膜。使用X射线衍射(XRD)、扫描电子显微镜(SEM)表征纳米复合薄膜材料的晶体结构和微观形貌,通过交流阻抗技术(EIS)和极化曲线(Polarization Curves)电化学方法研究不锈钢表面纳米复合薄膜在模拟海水体系中的腐蚀行为。结果表明:制备叠层式纳米复合薄膜TiO2为锐钛矿型,SnO2为金红石型;不锈钢表面构筑叠层式纳米SnO2/TiO2复合薄膜颗粒粒径小,分布均匀且表面致密。电化学测试表明,叠层式纳米SnO2/TiO2复合薄膜阻抗值高于TiO2薄膜,且对不锈钢基体阳极反应有明显钝化过程,具有良好防腐蚀性能;同时叠层式纳米SnO2/TiO2复合薄膜存在最优叠加SnO2层数,叠加3层SnO2的纳米SnO2/TiO2复合薄膜电极防腐蚀性能最佳。  相似文献   

GEOCHRONOMETRY & ISOTOPE GEOLOGY     

《Abstract of Chinese Geological Literature》2014,(4)

正20142333Liao Jin(State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China);Hu Chaoyong Thermoluminescence Based Thermometer from Stalagmites(Quaternary Sciences,ISSN1001-7410,CN11-2708/P,33(6),2013,p.1122-1129,6illus.,1table,48refs.)  相似文献   

Predicting dam-related downstream geomorphic response with widely available stream gauge data: A case study of the Godavari River Basin,India     

Joy Sanyal  Priyanka Dasgupta  Shinjiro Kanae 《Singapore journal of tropical geography》2020,41(2):284-298

Dam-related downstream adjustments of riverbeds are normally investigated by analysing the trend in sediment supply and high flow events during the pre- and post-dam periods. The required data for existing predictive models is not measured at river gauges, which limits the application of these tools. We derived the frequency of sediment-transporting streamflow events (T*) and upstream sediment supply (S*) in the pre- and post-dam periods with widely available gauged records and predicted changes in the downstream riverbed by adapting an existing model. Ten gauging stations in the Godavari River Basin, India, located downstream of dams, were chosen as study sites. Annually surveyed cross-sections at each site validated the accuracy of the predicted dam-related downstream changes. Then, a regression equation (R² = 0.75) was established between T*/S* (independent variable) and changes in the downstream bed elevation (dependent variable) for the Godavari Basin. We recommended that similar local empirical equations be formulated for larger river basins. Models of large-scale rainfall-runoff and sediment transport processes that can account for the influence of dams, such as the Soil & Water Assessment Tool, can be paired with the proposed regression equation to estimate dam-related downstream erosion and deposition with globally available data.  相似文献   

Three-dimensional hydromechanical modeling of internal erosion in dike-on-foundation     

Jie Yang  Zhen-Yu Yin  Farid Laouafa  Pierre-Yves Hicher 《国际地质力学数值与分析法杂志》2020,44(8):1200-1218

Currently, numerical studies at the real scale of an entire engineering structure considering internal erosion are still rare. This paper presents a three-dimensional (3D) numerical simulation of the effects of internal erosion within a linear dike located on a foundation. A two-dimensional (2D) finite element code has been extended to 3D in order to analyze the impact of internal erosion under more realistic hydromechanical conditions. The saturated soil has been considered as a mixture of four interacting constituents: soil skeleton, erodible fines, fluidized fine particles, and fluid. The detachment and transport of the fine particles have been modeled with a mass exchange model between the solid and the fluid phases. An elastoplastic constitutive model for sand-silt mixtures has been developed to monitor the effect of the evolution of both the porosity and the fines content induced by internal erosion upon the behavior of the soil skeleton. An unsaturated flow condition has been implemented into this coupled hydromechanical model to describe more accurately the seepage within the dike and the foundation. A stabilized finite element method was used to eliminate spurious numerical oscillations in solving the convection-dominated transport of fluidized particles. This numerical tool was then applied to a specific dike-on-foundation case subjected to internal erosion induced by a leakage located at the bottom of the foundation. Different failure modes were observed and analyzed for different boundary conditions, including the significant influence of the leakage cavity size and the elevation of the water level at the upstream and downstream sides of the dike.  相似文献   

陕北地区退耕还林还草工程土壤保护效应的时空特征   总被引：3，自引：0，他引：3  

刘文超  刘纪远  匡文慧 《地理学报》2019,74(9):1835-1852

以中国退耕还林生态工程重点区域陕北地区作为研究区,基于耕地遥感监测数据集,分析了陕北地区2000-2013年耕地的时空变化特征;基于梯田空间分布,对RUSLE模型进行改进,模拟生成陕北地区土壤侵蚀模数栅格数据并进行精度验证;最后结合耕地变化数据集对陕北地区退耕还林（草）地及未退耕地的土壤侵蚀变化特征进行对比分析,以明确工程对全区土壤侵蚀变化的影响。结果表明,2000-2010年,陕北退耕农田内部侵蚀模数减少了22.70 t/hm ²,是退耕农田区2000年土壤侵蚀模数的47.08%。同期,陕北地区未退耕农田侵蚀模数减少了10.99 t/hm ²,占未退耕农田区域2000年土壤侵蚀模数的28.60%。从陕北全区的角度看,各种土地利用类型2000-2010年土壤侵蚀模数平均减少了14.51 t/hm ²,占2000年全区土壤侵蚀模数的41.87%。由此可见,退耕还林还草工程可以有效减少土壤侵蚀模数,达到土壤保护的作用。其中,由耕地转为林草所导致的侵蚀减少最为显著,对土壤保护的贡献作用最大。但是,2010年以后（2010-2013年）为退耕还林还草巩固时期,因此该阶段陕北地区土壤侵蚀模数和土壤侵蚀量变化较前10年显著降低。  相似文献   

A stochastic model of sedimentation     

Richard Thompson 《Mathematical Geology》1984,16(8):753-778

A mathematical model is presented which describes the origin of the earth's geological record in terms of a stochastic process involving random events of sedimentation and erosion. The model yields quantitative predictions of the percentages of the earth's land area in which sediments of one geological period directly overlie those of any given earlier period. It also predicts the total amount of sediment dating from each geological period, and the percentage of the earth's surface marked by outcrops of this sediment. These computed quantities are shown to correlate well with corresponding quantities derived from empirical investigation.  相似文献   

基于复杂网络的城市公交网络研究综述     

陈光  温广辉  虞文武 《南京气象学院学报》2018,10(4):401-408

近年来,基于复杂网络理论的城市公交网络研究得到了人们的广泛关注,相关的研究成果有助于深入理解城市公交网络的运行机理,并为这类网络的设计、优化与控制提供帮助.首先介绍了城市公交网络的研究背景、城市公交系统的网络描述和相关的网络概念.然后从网络的静态特性分析、演化生成建模、行为研究和应用研究等方面对国内外的研究现状进行了总结和分析.最后,总结并讨论了当前基于复杂网络的城市公交网络的研究状况与发展机遇.  相似文献   

湖泊(水库)沉积物分析在土壤侵蚀研究中的运用   总被引：1，自引：1，他引：0  

薛天翼  王红亚 《地理科学进展》2018,37(7):890-900

土壤侵蚀研究对于防治自然灾害,实现土地的可持续利用具有重要的现实意义。由于一些地区长期以来水文观测资料较为匮乏,针对过去时间段内的土壤侵蚀研究通常需要寻找替代指标。湖泊(水库)作为流域内侵蚀产物的“汇”,其沉积物可不同程度地记录较长时期土壤侵蚀的具体特征,因此,基于湖泊(水库)沉积物分析的土壤侵蚀研究具有较强的应用价值和发展潜力。本文主要围绕确定土壤侵蚀年代,反演侵蚀过程,探寻沉积物来源的研究主线,详细论述了湖泊(水库)沉积物中放射性同位素、矿物磁性、粒度以及地球化学指标的应用原理和方法,分别总结了国内外学者利用湖泊(水库)沉积物在上述3个领域所取得的研究成果,在此基础上讨论了目前研究中存在的不确定性,并对未来的研究方向进行了展望。  相似文献   

Public Participation in Rural Environmental Governance around the Water Source of Xiqin Water Works in Fujian     

SU Shipeng  LI Xin  HUANG Ansheng  SUN Xiaoxia 《资源与生态学报(英文版)》2018,9(1):66-77

Public participation is an important way to improve the overall effect and social recognition of rural environmental governance in water source areas. Public participation makes environmental governance measures more targeted and effective, contributes to protecting the basic environmental rights of the public, and makes it easier to meet the livelihood needs of rural people. Public participation in rural environmental governance in water source areas is characterized by complex behavior and is dependent on public willingness to participate. Amongst other factors, it is subject to the combined influences of both internal (psychological cognition) and external (environmental regulation) conditions. This paper builds a theoretical framework for understanding public participation behavior in rural environmental governance, and uses it to analyze a case in the rural area surrounding the Xiqin Water Works in Fujian Province. In the case study, the public shows high willingness to participate, but low actual rates of participation. At the same time, the willingness of villagers to pay for the control of pollution from livestock and poultry breeding varies greatly from village to village, and there are also noticeable individual differences in public participation in the use of public collection points for rural household waste. We found that gender, understandings of environmental protection and perception of environmental regulation, play a key role in influencing the willingness of farmers to pay for the control of pollution from livestock and poultry breeding. Individual awareness of environmental protection, environmental protection facility conditions, and environmental service quality had a significant influence on public participation in the use of public collection points for rural household waste.  相似文献   

Application of the Static Headland-Bay Beach Concept to a Sandy Beach: A New Elliptical Model     

LI Bing  ZHUANG Zhenye  CAO Lihua  DU Fengchao 《中国海洋大学学报(英文版)》2020,19(1):81-89

The headland-bay beach is one of the most common coastal types in the world.Its morphology reflects the changes that occurred during long-term evolution of the sandy coast.Several headland-bay beach models have been proposed to simulate the coastline’s configuration in equilibrium.In this paper,a new elliptical model is proposed,described,and applied.On the east coast of Laizhou Bay in Shandong Province from Longkou Port to Diaolongzui,four typical headland-bay beaches have developed,and four headland-bay beach models are used in this paper to simulate the morphology of these beaches to assess the applicability of each model.The simulation results of the elliptical model verify that it is applicable to the study area.In addition,the elliptical model is easy to use.Through simulation and field investigations,we concluded that most of the coastal segments in this area will remain in an erosion state,and the human activity has a significant impact on the shoreline’s evolution.  相似文献