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模拟降雨条件下泥沙荷载随坡面侵蚀过程的变化(英文)
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作者 孙莉英 方海燕 +4 位作者 蔡强国 杨希华 和继军 周俊良 王训明 《地理学报:英文版》 SCIE CSCD 2019年第6期1001-1020,共20页
It is of great significance to quantify sediment load changing with erosion processes for improving the precision of soil loss prediction. Indoor rainfall experiments were conducted in 2 rainfall intensities(90 mm... It is of great significance to quantify sediment load changing with erosion processes for improving the precision of soil loss prediction. Indoor rainfall experiments were conducted in 2 rainfall intensities(90 mm·h-1 and 120 mm·h-1), four slope gradients(17.60%, 26.80%, 36.40%, 46.60%) and 2 slope lengths(5 m, 10 m). Erosion processes are divided into five stages. Results show that sediment yield is mainly sourced from rill erosion, contributing from 54.60% to 95.70% and the duration of which is extended by slope gradients. Sediment load and sediment concentration are significantly different along erosion stages, with the highest values in rill development stage(SIV). Surface flow velocities(interrill and rill) demonstrate less significant differences along erosion stages. Rainfall intensity increases sediment load in all stages, with up to 12.0 times higher when changing from 90 to 120 mm·h-1. There is an increasing trend for sediment load and sediment concentration with the rising slope gradient, however, fluctuations existed with the lowest values on 26.80% and 36.40%, respectively, among different treatments. The slope gradient effects are enhanced by rainfall intensity and slope length. Results from this study are important for validating and improving hillslope erosion modelling at each erosion stage. 展开更多
关键词 RAINFALL simulation EROSION EXPERIMENTS RILL EROSION interrill EROSION sediment load
不同冲蚀速度与角度下的防砂管冲蚀规律 预览
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作者 吕宁博 翟晓鹏 +2 位作者 张春阳 冯云爽 刘思雨 《化工设计通讯》 CAS 2019年第3期129-130,共2页
高速含砂流体的冲蚀作用造成的防砂管基管破坏是防砂失效的重要原因之一。利用旋转MSH冲蚀仪模拟地层环境,以含砂流体为实验介质,从筛管基管上裁剪出50mm×20mm×2mm的样块作为实验试样,研究其在固液两相流体中不同冲蚀速度与... 高速含砂流体的冲蚀作用造成的防砂管基管破坏是防砂失效的重要原因之一。利用旋转MSH冲蚀仪模拟地层环境,以含砂流体为实验介质,从筛管基管上裁剪出50mm×20mm×2mm的样块作为实验试样,研究其在固液两相流体中不同冲蚀速度与角度下的冲蚀规律。实验发现:相同实验条件下,冲蚀磨损量与冲蚀角度成反比、与冲蚀速度成正比且成指数增长。因此可以调整设计筛管结构以增大含砂流体与筛管基管的冲蚀角度,同时在油田开发前期降低生产速度,减小冲蚀磨损,后期增大生产速度,保证总体产量。 展开更多
关键词 防砂 筛管 冲蚀 固液两相流体 冲蚀角度 冲蚀速度
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An experimental study on the influences of water erosion on wind erosion in arid and semi-arid regions 预览
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作者 YANG Huimin ZOU Xueyong +1 位作者 WANG Jing’ai SHI Peijun 《干旱区科学:英文版》 SCIE CSCD 2019年第2期208-216,共9页
Complex erosion by wind and water causes serious harm in arid and semi-arid regions. The interaction mechanisms between water erosion and wind erosion is the key to further our understanding of the complex erosion. Th... Complex erosion by wind and water causes serious harm in arid and semi-arid regions. The interaction mechanisms between water erosion and wind erosion is the key to further our understanding of the complex erosion. Therefore, in-depth understandings of the influences of water erosion on wind erosion is needed. This research used a wind tunnel and two rainfall simulators to investigate the influences of water erosion on succeeding wind erosion. The wind erosion measurements before and after water erosion were run on semi-fixed aeolian sandy soil configured with three slopes(5°, 10° and 15°), six wind speeds(0, 9, 11, 13, 15 and 20 m/s), and five rainfall intensities(0, 30, 45, 60 and 75 mm/h). Results showed that water erosion generally restrained the succeeding wind erosion. At a same slope, the restraining effects decreased as rainfall intensity increased, which decreased from 70.63% to 50.20% with rainfall intensity increased from 30 to 75 mm/h. Rills shaped by water erosion could weaken the restraining effects at wind speed exceeding 15 m/s mainly by cutting through the fine grain layer, exposing the sand layer prone to wind erosion to airflow. In addition, the restraining effects varied greatly among different soil types. The restraining effects of rainfall on the succeeding wind erosion depend on the formation of a coarsening layer with a crust and a compact fine grain layer after rainfall. The findings can deepen the understanding of the complex erosion and provide scientific basis for regional soil and water conservation in arid and semi-arid regions. 展开更多
关键词 WIND EROSION WATER EROSION SANDY soil particle size surface ROUGHNESS wind-water EROSION agriculturalpastoral ECOTONE
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Partition-coordinated control of soil and water loss for chestnut forests in the Yanshan Mountain Region,China 预览
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作者 Xinhui Ding Guangquan Liu +2 位作者 Xiaoying Liu Yongsheng Xie Zhichun Yue 《国际泥沙研究:英文版》 SCIE 2019年第1期58-64,共7页
Soil erosion from chestnut forests is one of the most important factors causing land degradation in the Yanshan Mountain Region.A 2-year field study was done to compare the effects on erosion of a control plot(CP),a r... Soil erosion from chestnut forests is one of the most important factors causing land degradation in the Yanshan Mountain Region.A 2-year field study was done to compare the effects on erosion of a control plot(CP),a repaired and maintained horizontal ditch built with an engineering baffle every 6m(MP 1),and a repaired and maintained horizontal ditch built with an engineering baffle every 8m(MP 2).The results showed that the slope runoff of chestnut forests was influenced by rainfall characteristic factors.No single rainfall characteristic factor showed dominance for hill slope runoff.The runoff reduction effect of the partition-coordinated erosion control measures(MP 1 and MP 2)was substantial for chestnut forests under high rainfall intensity conditions.However,the runoff reduction efficiency was higher under the conditions of heavy rainfall and low average rainfall intensity than for storms with higher intensity and lower total rainfall.The reduction effect of the partition-coordinated erosion control measures on the runoff and sediment yield of chestnut forest slopes was MP 2 4 MP 1 4 CP.The runoff reduction rate and erosion reduction rate of MP 2 reached 61.70%and 97.41%,respectively,and that for MP 1 was 54.15%and 85.31%,respectively.Therefore,after a comprehensive comparison,MP 2 was determined to be more effective for soil erosion control for a sloping chestnut forest. 展开更多
关键词 CHESTNUT forest Soil and water loss EROSION control RUNOFF REDUCTION RATE EROSION REDUCTION RATE
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基于CSLE模型和抽样单元法的县域土壤侵蚀估算方法对比 预览
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作者 李子轩 赵辉 +3 位作者 邹海天 李依珊 刘雨鑫 李骜 《农业工程学报》 EI CAS CSCD 北大核心 2019年第14期141-148,共8页
为提高县域尺度地块(栅格)土壤侵蚀模数估算的准确性,以河北省怀来县为例,基于CSLE模型,分别采用全域覆盖计算和4%密度抽样单元推算方法对全县土壤侵蚀进行计算和对比分析。结果表明:全域覆盖计算比4%抽样单元推算水土流失面积大59.0km... 为提高县域尺度地块(栅格)土壤侵蚀模数估算的准确性,以河北省怀来县为例,基于CSLE模型,分别采用全域覆盖计算和4%密度抽样单元推算方法对全县土壤侵蚀进行计算和对比分析。结果表明:全域覆盖计算比4%抽样单元推算水土流失面积大59.0km^2,相对差异达12.94%。全域覆盖计算可实现空间全覆盖,更准确地反映县域水土流失空间分布特点,适用于中、小尺度土壤侵蚀定量计算,但需要较高精度和全面的数据源保证;抽样单元推算适用于流域、区域等大尺度土壤侵蚀估算,但结果受抽样方法、抽样密度、外推或插值方法等因素影响较大。应进一步加强遥感解译准确性、侵蚀因子精度等对CSLE全域覆盖计算结果影响的研究,完善模型参数数据库,率定因子值,实现参数本地化。 展开更多
关键词 土壤 侵蚀 估算 CSLE模型 全域覆盖计算 抽样单元推算 土壤侵蚀评估 县域
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A Conservative Approach to Treatment of Dental Erosion: Case Report 预览
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作者 Khaila Davis Risa Yuk Low Reisha Rafeek 《口腔学期刊(英文)》 2019年第11期241-248,共8页
Tooth surface loss is a common condition with nearly three-quarter of the population in Trinidad & Tobago exhibiting signs and about one-fifth of those persons have moderate or severe wear. These patients become d... Tooth surface loss is a common condition with nearly three-quarter of the population in Trinidad & Tobago exhibiting signs and about one-fifth of those persons have moderate or severe wear. These patients become difficult to treat due mainly to loss of clinical crown height and also loss of occlusal vertical dimension. This case depicts the use of a conservative approach to treating a patient with moderate tooth surface loss, as assessed via the tooth wear index, with aetiology of acid erosion. The poor appearance of the dentition was the patient’s chief presenting complaint. With the use of 3M Filtek? Z 250 Universal Restorative Composite (St Paul, MN, USA), temporary posterior build-ups were placed to increase the patient’s Occlusal Vertical Dimension (OVD) and were subsequently replaced with metal onlays. Anterior composite veneers were placed to achieve an aesthetically pleasing result at the increased OVD. The combined use of composite and metal onlays allowed for an economical and more conservative treatment modality for dental erosion rather than full coverage posterior and anterior crowns. 展开更多
关键词 EROSION TOOTH WEAR Onlays VENEERS
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Use of incipient motion data for backward erosion piping models 预览
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作者 Vera M. van Beek Bryant A. Robbins +2 位作者 Gijs J.C.M. Hoffmans Adam Bezuijen Leo C. van Rijn 《国际泥沙研究:英文版》 SCIE 2019年第5期401-408,共8页
Backward erosion piping involves the gradual removal of granular material under the action of water flow from the foundation of a dam or levee, whereby shallow pipes are formed that grow in the direction opposite to t... Backward erosion piping involves the gradual removal of granular material under the action of water flow from the foundation of a dam or levee, whereby shallow pipes are formed that grow in the direction opposite to the flow. This pipe-forming process can ultimately lead to failure of a water-retaining structure and is considered one of the most important failure mechanisms for dikes and levees in the Netherlands and the United States. Modeling of this mechanism requires the assessment of hydraulic conditions in the pipe, which are controlled by the particle equilibrium at the pipe wall. Since the pipe's dimensions are controlled by the inflow to the pipe from the porous medium, the flow through the pipe is thought to be laminar for fine- to medium-grained sands. The literature provides data for incipient motion in laminar flow, which is reviewed here and complemented with data from backward erosion experiments. The experiments illustrate the applicability of the laminar incipient motion data to determine the erosion pipe dimensions and corresponding pipe hydraulics for fine- to medium-grained sands, for the purpose of backward erosion piping modeling. 展开更多
关键词 Internal EROSION BACKWARD EROSION PIPING CYLINDRICAL test Incipient motion DIKES LEVEES
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陕北子洲“7·26”暴雨后坡耕地细沟侵蚀及其影响因素分析 预览
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作者 王颢霖 焦菊英 +4 位作者 唐柄哲 陈一先 白雷超 王楠 张意奉 《农业工程学报》 EI CAS CSCD 北大核心 2019年第11期122-130,共9页
细沟侵蚀研究多数基于模拟降雨条件,野外自然状态下的研究相对较少,而极端暴雨条件下的细沟侵蚀研究更为鲜见。该文对陕西子洲2017年"7·26"特大暴雨条件下坡耕地发育的细沟开展调查,研究坡位(距分水岭距离)、坡度和坡形... 细沟侵蚀研究多数基于模拟降雨条件,野外自然状态下的研究相对较少,而极端暴雨条件下的细沟侵蚀研究更为鲜见。该文对陕西子洲2017年"7·26"特大暴雨条件下坡耕地发育的细沟开展调查,研究坡位(距分水岭距离)、坡度和坡形对坡耕地细沟侵蚀特征的影响。结果表明:通过对35个样方的143条细沟统计,细沟宽度和细沟深度分别为0.5~60 cm和0.5~35 cm;细沟侵蚀强度、细沟密度和细沟割裂度分别为2 289~110 976 t/km^2、0.3~3.95 m/m^2和0.002~0.441。随距分水岭距离(17~58 m)的增加,细沟先快速发育,坡面破碎程度加剧,距分水岭58m后,细沟发育减慢,坡面破碎程度减弱。坡度在不同的坡位对细沟侵蚀的影响程度不同:随坡度增大,上坡位(距分水岭20~40m),细沟侵蚀强度陡升,坡面破碎程度加剧;下坡位(距分水岭60~80m),细沟侵蚀强度增加较缓慢,坡面破碎程度减弱。凸形坡中部为细沟侵蚀(10 292t/km^2)最为严重区域,下部(8 141t/km^2)次之,上部无细沟发生;细沟密度、细沟割裂度和细沟平均宽度先增大后减小,细沟平均深度递增。浅沟地形细沟侵蚀随距分水岭距离的增加而增加,但退耕地的存在减缓了细沟侵蚀发育程度。直形坡因坡度最大其细沟侵蚀最严重,细沟形态同其他坡形基本相同,但最大沟宽和沟深均大于其他坡形。研究结果可为黄土高原坡耕地的水土流失防治提供参考。 展开更多
关键词 土壤 侵蚀 暴雨 细沟侵蚀 坡耕地 坡形 坡度 距分水岭距离
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鞍钢高炉炉缸异常侵蚀的原因及对策探析
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作者 姜喆 车玉满 +2 位作者 郭天永 谢明辉 李建军 《炼铁》 北大核心 2019年第2期5-8,共4页
对鞍钢近年来高炉炉缸破损调查情况进行了阐述。从炉缸侵蚀的状况来看,铁水环流、炭砖应力破坏、化学氧化侵蚀和炭素胶泥的质量不合格是鞍钢高炉炉缸异常侵蚀的主要原因。另外,基于对炉衬侵蚀原因和特征的分析.提出了应从设计、制造与... 对鞍钢近年来高炉炉缸破损调查情况进行了阐述。从炉缸侵蚀的状况来看,铁水环流、炭砖应力破坏、化学氧化侵蚀和炭素胶泥的质量不合格是鞍钢高炉炉缸异常侵蚀的主要原因。另外,基于对炉衬侵蚀原因和特征的分析.提出了应从设计、制造与施工、烘炉、开炉和日常生产操作等方面采取有措施,以延长高炉炉缸使用寿命。 展开更多
关键词 高炉 炉缸 侵蚀 铁水环流 化学侵蚀
冲蚀磨损机理及抗冲蚀涂层研究进展 预览
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作者 李力 魏天酬 +1 位作者 刘明维 周超 《重庆交通大学学报:自然科学版》 CAS CSCD 北大核心 2019年第8期70-74,91共6页
冲蚀磨损现象广泛存在于工程结构中,是许多行业结构破坏与装备失效的主要原因之一,每年造成能源与材料上的巨大经济损失。综合评述了微切削理论、变形磨损理论、磨损脱层理论、二次冲蚀理论和锻造挤压理论等塑性材料冲蚀理论以及弹性压... 冲蚀磨损现象广泛存在于工程结构中,是许多行业结构破坏与装备失效的主要原因之一,每年造成能源与材料上的巨大经济损失。综合评述了微切削理论、变形磨损理论、磨损脱层理论、二次冲蚀理论和锻造挤压理论等塑性材料冲蚀理论以及弹性压痕理论等脆性材料冲蚀理论,并且针对现有主要冲蚀防护方法中的涂层保护法抗冲蚀原理作出介绍,最后提出了目前冲蚀磨损相关研究中的主要问题和未来的研究重点。 展开更多
关键词 航道工程 冲蚀磨损 冲蚀理论 涂层
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Soil loss estimation using rusle model to prioritize erosion control in KELANI river basin in Sri Lanka 预览
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作者 Cassim Mohamed Fayas Nimal Shantha Abeysingha +2 位作者 Korotta Gamage Shyamala Nirmanee Dinithi Samaratunga Ananda Mallawatantri 《国际水土保持研究(英文)》 2019年第2期130-137,共8页
Soil erosion contributes negatively to agricultural production,quality of source water for drinking,ecosystem health in land and aquatic environments,and aesthetic value of landscapes.Approaches to understand the spat... Soil erosion contributes negatively to agricultural production,quality of source water for drinking,ecosystem health in land and aquatic environments,and aesthetic value of landscapes.Approaches to understand the spatial variability of erosion severity are important for improving landuse management.This study uses the Kelani river basin in Sri Lanka as the study area to assess erosion severity using the Revised Universal Soil Loss Equation (RUSLE) model supported by a GIS system.Erosion severity across the river basin was estimated using RUSLE,a Digital Elevation Model (15 × 15 m),twenty years rainfall data at 14 rain gauge stations across the basin,landuse and land cover,and soil maps and cropping factors.The estimated average annual soil loss in Kelani river basin varied from zero to 103.7 t ha-1 yr-1,with a mean annual soil loss estimated at 10.9 t ha-1 yr-1.About 70% of the river basin area was identified with low to moderate erosion severity (< 12 t ha-1 yr-1) indicating that erosion control measures are urgently needed to ensure a sustainable ecosystem in the Kelani river basin,which in turn,is connected with the quality of life of over 5 million people.Use of this severity information developed with RUSLE along with its individual parameters can help to design landuse management practices.This effort can be further refined by analyzing RUSLE results along with Kelani river sub-basins level real time erosion estimations as a monitoring measure for conservation practices. 展开更多
关键词 Kelani river basin Revised UNIVERSAL SOIL loss equation RUSLE SOIL EROSION SOIL EROSION HAZARD map Land degradation
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不同沙埋程度下带状沙障的防风固沙效果研究 预览
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作者 袁立敏 黄海广 +1 位作者 闫德仁 胡小龙 《农业工程学报》 EI CAS CSCD 北大核心 2019年第16期172-179,共8页
沙障在防护过程中,易发生沙障沙埋现象。为了对比分析不同沙埋程度下沙障的防风固沙效果差异,该文通过风洞模拟和野外试验相结合的方法,研究了沙袋沙障在裸露、浅埋、深埋3种状态下,防护区近地层风流场、输沙通量等风沙运动规律,并以未... 沙障在防护过程中,易发生沙障沙埋现象。为了对比分析不同沙埋程度下沙障的防风固沙效果差异,该文通过风洞模拟和野外试验相结合的方法,研究了沙袋沙障在裸露、浅埋、深埋3种状态下,防护区近地层风流场、输沙通量等风沙运动规律,并以未设置沙障的流沙区作为对照,明确了沙埋过程中沙障的防风固沙效果变化规律。结果表明,沙障在经历裸露至深埋过程中:1)对过境气流的防护距离、防护高度逐渐减小,近地层风速廓线变化趋势与对照相同,并逐渐服从对数函数;2)沙障防护区输沙分布高度显著降低(P<0.01),输沙分布高度由42 cm(裸露)降低至34 cm(浅埋),最终降至28 cm(深埋),而对照的输沙分布高度为24 cm;3)近地层输沙率分布曲线逐渐服从对数函数,0~50 cm高度范围输沙量也呈现递增趋势;4)3种埋设深度野外试验说明,经过两个风季后,裸露、浅埋、深埋的沙袋沙障防护区土壤风蚀呈现降低趋势,风蚀深度分别比对照降低了18.53%、72.97%、80.40%。研究可以为沙障高度优化及应用技术提升提供理论依据。 展开更多
关键词 土壤 侵蚀 沙障 风蚀 风速流场 风速廓线 输沙量
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The Protective Role of a Riparian Vegetation to the Sources of a Rural Watershed 预览
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作者 Fernando Frachone Neves Auré +2 位作者 lio Teodoro Fontes André Luiz Oliveira 《水资源与保护(英文)》 2019年第4期419-433,共15页
A recent review of the Brazilian forest law has suggested the possibility of decrease the riparian buffer width along the banks of waterways. This vegetation can trap solutes which had been deposited in the soil and w... A recent review of the Brazilian forest law has suggested the possibility of decrease the riparian buffer width along the banks of waterways. This vegetation can trap solutes which had been deposited in the soil and which would otherwise be carried to the waterways in runoff water. In the current study, we applied the AVSWAT model to the Rio Bonito micro-basin of city of Descalvado, State of S?o Paulo, Brazil, to verify the amount of nitrogen (N) and phosphorous (P) entering the water resource, and to evaluate the environmental protection provided by the riparian vegetation zones. Our results demonstrate this protection is effective in reducing the amount of nitrogen (N) and phosphorous (P) carried to the river. The scenario produced by the data could be used to diagnose the contamination of this particular watershed and to indicate the measures that should be adopted to ensure the restoration and preservation of riparian vegetation zones. 展开更多
关键词 AVSWAT WATERSHED EROSION NITROGEN Phosphorous
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基于三维重建技术的坡面细沟侵蚀演变过程研究 预览
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作者 吴淑芳 刘勃洋 +4 位作者 雷琪 孙立全 郭慧莉 冯喆 钱阔 《农业工程学报》 EI CAS CSCD 北大核心 2019年第9期114-120,共7页
作为黄土高原地区沟头溯源侵蚀和水流汇集发源地的梁峁坡面,在强降雨下其产流产沙对沟缘线以下坡面及沟道侵蚀有着重大影响。该研究根据野外实地考查构建5°~35°变坡段实体模型,进行6场间歇性人工模拟降雨试验,并借助基于三维... 作为黄土高原地区沟头溯源侵蚀和水流汇集发源地的梁峁坡面,在强降雨下其产流产沙对沟缘线以下坡面及沟道侵蚀有着重大影响。该研究根据野外实地考查构建5°~35°变坡段实体模型,进行6场间歇性人工模拟降雨试验,并借助基于三维重建技术的PhotoScan软件获取坡面DEM,将其侵蚀演化过程进行图形化、数字化,定性定量揭示其侵蚀形态演变特征。研究表明:1)梁峁坡面细沟侵蚀历经4个阶段:面蚀阶段,即产生一系列呈串珠状分布的侵蚀跌坑,宽度5~9cm,深度1~4cm;细沟形成阶段,由面蚀所产生的微小跌坑在径流作用下长、宽、深均不断增大,最大分别达到266、7.6、13.8cm;细沟网形成阶段,细沟出现分叉及联通,有明显流路;小切沟形成阶段,伴随沟壁崩塌、沟壁加宽和沟底下切,最大沟长及最大沟深较细沟形成时增大3倍以上。2)对比次降雨过程基于三维建模所计算侵蚀量与实测侵蚀量,第1场降雨试验因地表疏松颗粒较多导致实测侵蚀量比建模计算侵蚀量大而引起较大偏差(20.82%),其他场次偏差均在10%左右或以下,总体来说,该技术可以较好地应用于侵蚀发育过程的研究。该研究实现侵蚀演变关键过程图形化、数字化,有助于人们定性、定量了解和认识梁峁坡面侵蚀过程,且对于创新侵蚀过程研究方法亦具有实践指导价值。 展开更多
关键词 土壤 侵蚀 照片重建 人工模拟降雨试验 细沟侵蚀 演化过程
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Riverbank Erosional Features in the Stanley Pool of the Congo River and Some Geotechnical Classifications of the Sands 预览
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作者 Guy Dieudonne Moukandi N’Kaya Narcisse Malanda +2 位作者 Olivier Florent Essouli Bernard Mabiala Alain Laraque 《地球科学和环境保护期刊(英文)》 2019年第5期152-167,共16页
The Stanley Pool, an almost circular island about thirty kilometers in diameter, crossed by the Congo River, is subject to diversified erosion of its riverbanks. This study highlights description using geotechnical pa... The Stanley Pool, an almost circular island about thirty kilometers in diameter, crossed by the Congo River, is subject to diversified erosion of its riverbanks. This study highlights description using geotechnical particle size distribution analysis of soils of the shoreline that make up the shoreline. Three critical areas of the island were examined to characterize the origins of these erosion phenomena. The results obtained show that the soil materials are mostly sands with very fine or fine grains characteristic of very unstable soils. The morpho-sedimentological characteristics of the areas studied show that these soils are plastic (with a Plasticity Index between 15 percent and 19 percent). The presence of water, action of currents or groundwater flow easily destabilize the materials that make up the riverbank and cause the fines to creep (Collapse of sandy riverbanks, Landslide of sandy riverbanks, …). 展开更多
关键词 Erosion Riverbanks CONGO RIVER Stanley POOL GEOTECHNICAL Analysis Particle Size Distribution
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An Earthquake Model Based on Fatigue Mechanism—A Tale of Earthquake Triad 预览
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作者 Diandong Ren 《地球科学和环境保护期刊(英文)》 2019年第8期290-326,共37页
Earthquakes are the result of strain build-up from without and erosion from within faults. A generic co-seismic condition includes merely three angles representing respectively fault geometry, fault strength and the r... Earthquakes are the result of strain build-up from without and erosion from within faults. A generic co-seismic condition includes merely three angles representing respectively fault geometry, fault strength and the ratio of fault coupling to lithostatic load. Correspondingly, gravity fluctuation, bridging effect, and granular material production/distribution form the earthquake triad. As a dynamic component of the gravity field, groundwater fluctuation is the nexus among the three intervened components and plays a pivotal role in regulating major earthquake irregularity: reducing natural (dry) inter-seismic periods and lowering magnitudes. It may act mechanical-directly (MD) through super-imposing a seismogenic lateral stress field thus aiding plate-coupling from without;or mechanical-indirectly (MI) by enhancing fault fatigue, hence weakening the fault from within. A minimum requirement for a working earthquake prediction system is stipulated and implemented into a well-vetted numerical model. This fatigue mechanism based modeling system is an important supplement to the canonical frictional theory of tectonic earthquakes. For collisional systems (e.g., peri-Tibetan Plateau regions), MD mechanism dominates, because the orographically-induced spatially highly biased precipitation is effectively channeled into deeper depth by the prevalence of through-cut faults. Droughts elsewhere also are seismogenic but likely through MI effects. For example, ENSO, as the dominant player for regional precipitation, has strong influence on the gravity field over Andes. Major earthquakes, although bearing the same 4 - 7 years occurrence frequency as ENSO, have a significant hiatus, tracing gravity fluctuations. That granular channels left behind by seamounts foster major earthquakes further aver the relevance of MI over Andes. Similarly, the stability of the Cascadia fault is found remotely affected by Californian droughts (2011-15), which created a 0.15 kPa/km stress gradient along the Pacific range, which also is the wave guid 展开更多
关键词 EARTHQUAKES EROSION Co-Seismic
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沙粒形状对风力机翼型磨损特性及临界颗粒Stokes数的影响 预览
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作者 李德顺 王亚娥 +2 位作者 郭兴铎 李银然 李仁年 《农业工程学报》 EI CAS CSCD 北大核心 2019年第12期224-231,共8页
风力机不可避免地运行在风沙环境下,风沙对风力机叶片的磨损将造成机组的气动性能下降和发电量降低。研究风沙对风力机翼型的冲蚀磨损特性时,通常将沙尘颗粒简化为球形颗粒,忽略了实际非球形颗粒的影响,相关研究表明颗粒形状对材料的冲... 风力机不可避免地运行在风沙环境下,风沙对风力机叶片的磨损将造成机组的气动性能下降和发电量降低。研究风沙对风力机翼型的冲蚀磨损特性时,通常将沙尘颗粒简化为球形颗粒,忽略了实际非球形颗粒的影响,相关研究表明颗粒形状对材料的冲蚀磨损率有一定的影响,该文以NACA 0012翼型直叶段为对象,研究沙尘颗粒形状对风力机翼型的磨损特性、气动性能及其临界颗粒Stokes数的影响规律。通过对风沙环境下NACA 0012翼型直叶段的流场进行数值模拟,研究了4种不同形状(颗粒形状因子分别为0.671、0.75、0.846和1)颗粒情况下,风力机翼型的磨损特性随颗粒体积当量直径的变化规律,以及颗粒形状对翼型开始发生磨损时临界颗粒Stokes数范围的影响规律。结果表明:来流风速为14.6 m/s、攻角为6°时,4种颗粒形状下翼型的最大磨损率均随颗粒体积当量直径的增大先增大后减小然后再增大,颗粒直径达到80μm为翼型最大磨损率的转折点;同一颗粒体积当量直径时,球形颗粒比非球形颗粒对翼型的冲蚀磨损程度小;颗粒形状对翼型升力系数和升阻比的影响很小;4种颗粒形状情况下,翼型表面的磨损区域均随颗粒体积当量直径的增大逐渐从翼型的前缘附近沿翼型压力面向尾缘扩展,并且翼型磨损最严重区域出现在前缘附近;颗粒形状会影响翼型开始发生磨损的临界颗粒Stokes数范围,颗粒形状因子越小,翼型开始发生磨损的临界颗粒Stokes数越大,Stokes数可以作为判断翼型表面是否发生磨损的依据。研究结果可为风力机叶片的防风沙磨损设计提供参考。 展开更多
关键词 风力机 磨损 翼型 颗粒形状 Stokes数
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震后极端降雨下流域产沙及物质运移规律模拟——以四川省洪溪河流域为例 预览
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作者 谢军 汪明 刘凯 《水土保持研究》 CSCD 北大核心 2019年第1期1-7,共7页
汶川地震引发的滑坡产生了大量松散物质,在极端降雨事件驱动下进入下游河道,导致河床淤升,河道变宽,给沿河道地势较低的居民区形成了新的洪涝风险。基于四川洪溪河流域2013年极端降雨数据,从无强降雨事件情景开始逐渐加大降雨强度及频... 汶川地震引发的滑坡产生了大量松散物质,在极端降雨事件驱动下进入下游河道,导致河床淤升,河道变宽,给沿河道地势较低的居民区形成了新的洪涝风险。基于四川洪溪河流域2013年极端降雨数据,从无强降雨事件情景开始逐渐加大降雨强度及频次生成6个不同降雨情景。运用凯撒二维水动力地表景观演变模型(CAESAR-lisflood)模拟不同降雨情景下流域产沙以及物质运移规律及其空间分布格局。结果表明:随着降雨强度的增加,流域出口产沙量以及流域总产沙量都呈非线性的增加趋势,且累积产沙量在极端降雨事件发生前后有明显的突变现象;各个降雨情景下侵蚀堆积的严重程度以及影响范围差异明显;震后流域遭到破坏的植被对流域的物质运移规律及空间分布格局有较大的影响,在较少滑坡、泥石流灾害的上游地区和滑坡、泥石流灾害严重的中下游地区水土流失程度差异明显。 展开更多
关键词 产沙 极端降雨 CAESAR-lisflood 流域 侵蚀 堆积
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苯甲酸利扎曲普坦鼻用温度-离子敏感型原位凝胶的体外溶蚀特性及安全性评价
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作者 王军 何文 《中国药师》 CAS 2019年第7期1338-1340,共3页
目的:对苯甲酸利扎曲普坦(RB)鼻用温度-离子敏感型原位凝胶的体外溶蚀及安全性进行研究。方法:采用体外振荡法检测RB鼻用温度-离子敏感型原位凝胶的基质溶蚀及药物释放特性。以生理盐水为正常对照,1%去氧胆酸钠为阳性对照,观察RB鼻用温... 目的:对苯甲酸利扎曲普坦(RB)鼻用温度-离子敏感型原位凝胶的体外溶蚀及安全性进行研究。方法:采用体外振荡法检测RB鼻用温度-离子敏感型原位凝胶的基质溶蚀及药物释放特性。以生理盐水为正常对照,1%去氧胆酸钠为阳性对照,观察RB鼻用温度-离子敏感型原位凝胶对蟾蜍上腭纤毛运动及形态的影响,以及对大鼠鼻黏膜形态的影响。结果:RB鼻用温度-离子敏感型原位凝胶的基质溶蚀及释药均为零级动力学过程,溶蚀方程为A=0.092 2t+0.198 8(r=0.998 6),释药方程为Q=0.246 0t+1.846 2(r=0.997 7),且两者有明显的线性相关性:Q=0.352 5A-0.424 8(r=0.999 0)。与正常对照组相比,RB鼻用温度-离子敏感型原位凝胶对蟾蜍纤毛运动能力无显著影响(P>0.05),且纤毛分布均匀,排列整齐,同时对大鼠鼻黏膜无明显的毒性。结论:RB从原位凝胶中的释放主要受凝胶溶蚀控制,同时具有良好的鼻用安全性。 展开更多
关键词 苯甲酸利扎曲普坦 温度-离子敏感型原位凝胶 溶蚀 释药 安全性评价
Morphodynamics of sandy beaches under the influence of storm sequences: Current research status and future needs 预览
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作者 Sonja Eichentopf Harshinie Karunarathna Jose M.Alsina 《水科学与水工程:英文版》 EI CAS CSCD 2019年第3期221-234,共14页
This paper reviews and discusses the current research status, trends, and future needs in the field of beach morphodynamics under the influence of storm sequences.The paper reviews how the three main research methods,... This paper reviews and discusses the current research status, trends, and future needs in the field of beach morphodynamics under the influence of storm sequences.The paper reviews how the three main research methods, field investigations, numerical modelling, and physical modelling, have been used to study beach morphodynamics during storm sequences.Available quantitative definitions of storm sequences at different sites are presented and discussed.It is shown that the definition of storm sequences is site-specific and requires knowledge of the storm climate, beach characteristics, and the temporal scale of beach recovery.Subsequently, the paper brings together currently available approaches aimed at describing the effect of storm sequences on beach erosion in a general way.The importance of storm chronology and the effects of an extreme storm within a sequence of storms are highlighted.Following that, the more poorly studied aspect of beach recovery in between storms within a sequence is discussed.Three indicators for defining beach recovery, namely the shoreline location, sediment volumes, and the beach state, are identified and compared.Finally, important research needs, including the need for detailed physical modelling, are identified. 展开更多
关键词 STORM SEQUENCES BEACH MORPHODYNAMICS BEACH erosion Extreme storms RETURN period BEACH recovery
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