Performance of ethylene-vinyl acetate foam as cushioning material for rigid debris-resisting barriers     

Carlos Lam  Julian S. H. Kwan  Y. Su  Clarence E. Choi  Charles W. W. Ng 《Landslides》2018,15(9):1779-1786

This paper reports an investigation on the performance of ethylene-vinyl acetate (EVA) foam when used as a cushion layer for rigid barriers used to resist debris flow. Large-scale pendulum impact tests were conducted to study the effects of layer thickness on cushion performance under six successive impacts. Results show that for the first impact at 70 kJ, the peak contact force with the EVA foam thickness of 500 mm is about twice larger compared to that of 1000 mm. Results also reveal that the cushion mechanism of elastic collapse of cell walls in the EVA foam results in peak contact forces and maximum transmitted loads that are up to 30 and 50% lower compared to gabions for the first impact at 70 kJ, respectively. The elastic behavior of EVA foam provides consistent cushioning efficiency. Furthermore, EVA foam is found to be susceptible to degradation by ultraviolet light so that a suitable coating layer is required for outdoor use. Polyurea was identified as a suitable coating material and a small-scale coating trial was performed to confirm this. Findings presented in this paper will have direct implications on the future design of cushion layers for rigid barriers used to intercept debris flows.  相似文献   

Geochemical and isotopic characteristics of fluids in the Niutuozhen geothermal field,North China     

Jumei Pang  Zhonghe Pang  Min Lv  Jiao Tian  Yanlong Kong 《Environmental Earth Sciences》2018,77(1):12

Niutuozhen geothermal field is located in the Jizhong graben, belonging to the northern part of Bohai Bay Basin in North China. Chemical and isotopic analyses were carried out on 14 samples of the geothermal fluids discharged from Neogene Minghuazhen (Nm), Guantao (Ng), and Jixianian Wumishan (Jxw) formations. The δ²H and δ¹⁸O in water, δ¹³C in CH₄, δ¹³C in CO₂, and ³He/⁴He ratio in the gases were analyzed in combination with chemical analyses on the fluids in the Niutuozhen geothermal field. The chemical and isotopic compositions indicate a meteoric origin of the thermal waters. The reservoir temperatures estimated by chemical geothermometry are in the range between 60 and 108 °C. The results show that the gases are made up mainly by N₂ (18.20–97.42 vol%), CH₄ (0.02–60.95 vol%), and CO₂ (0.17–25.14 vol%), with relatively high He composition (up to 0.52 vol%). The chemical and isotopic compositions of the gas samples suggest the meteoric origin of N₂, predominant crustal origins of CH₄, CO₂, and He. The mantle-derived He contributions are calculated to be from 5 to 8% based on a crust–mantle binary mixing model. The deep temperatures in the Jxw reservoir were evaluated based on gas isotope geothermometry to be in the range from 141 to 165 °C. The mantle-derived heat fraction in the surface heat flow is estimated to be in the range of 48–51% based on ³He/⁴He ratios.  相似文献   

Anthropogenic ¹²⁹I in seawaters along the north-central part of the English Channel: Levels and tracer applications     

Peng He  Zheng Yang  Hongying Pang  Ala Aldahan  Xiaolin Hou  G?ran Possnert  Xiangjun Pei  Yi Huang 《海洋学报(英文版)》2022,41(11):73-80

The English Channel (the Channel) represents a major sink and transport pathway of anthropogenic radioactive 129I. Despite this important role, data concerning the distribution of 129I in seawater of the Channel are scarce, and most of existing data are restricted to the eastern part of the Channel. The advection and dispersion of 129I from the French coast toward the central and further the English coast, especially in the Channel west of Cap de La Hague, are not fully investigated. We present results of iodine isotopes (127I and 129I) analyses of surface water samples collected along the central English Channel in October, 2010. The data show high 129I concentrations between Dover Strait and La Hague, followed by a dramatic drop towards the Celtic Sea and reveal the dispersal of 129I towards central and northern part of the Channel. Our observation also implies that the entire British coast is contaminated by 129I. 129I levels in the westernmost English Channel, close to the English coast, may reflect combined influences from La Hague and Sellafield. Evolution of 129I between 2005 and 2010 suggests a strong link to temporal marine discharges from La Hague plant. The discharges from the nuclear reprocessing facility have continued since 2010 and thus an ecological evaluation of 129I radioactive hazards in the environment of the Channel may be needed.  相似文献   

区域认知素养的培养体系探究     

庞玲  高俊昌 《地理教学》2022,(2):4-9

地理核心素养的培养是中学地理课程教学的核心任务,而核心素养的落实关键在于如何将其与课程内容有机结合,在于如何将每项核心素养细化,使培养目标和学生最终要达到的水平既科学合理又具备可操作性。区域认知是地理核心素养的重要组成部分。本研究针对区域认知素养,尝试构建一个面向中学地理课程教学的区域认知培养体系。该体系从区域视角、区域方法和区域评价三个方面构建,并根据具体情况将这三方面分为多个维度,提出每个维度不同水平层级的具体表现。  相似文献   

Morphology and distribution of the three epiphytic dinoflagellate species Coolia monotis,C. tropicalis,and C. canariensis (Ostreopsidaceae,Gonyaulacales, Dinophyceae) from Vietnamese coastal waters     

The V. Ho  Lam N. Nguyen 《Ocean Science Journal》2014,49(3):211-221

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Petrogenetic implications of mineral chemical data for the Permian Baima igneous complex, SW China   总被引：1，自引：0，他引：1  

J. Gregory Shellnutt  Kwan-Nang Pang 《Mineralogy and Petrology》2012,106(1-2):75-88

The Late Permian Fe-Ti oxide ore-bearing Baima igneous complex (BIC) is one of three gabbro-granitoid complexes with the Emeishan large igneous province. Mineral compositions are determined for the BIC layered gabbro in order to constrain subsolidus and magma chamber processes. The averaged compositions of cumulus olivine, clinopyroxene and plagioclase within individual samples range from Fo_65-76, Mg# = 75 to 82 and An_49-64 but they are not correlative. The observed mineral compositions are consistent with those modeled using the pHMELTS program. Highly variable magnetite compositions are consistent with extensive subsolidus re-equilibration and exsolution. The occurrence of reversely-zoned granular olivine in Fe-Ti oxide ores is a manifestation of Mg transfer between Fe-Ti oxides and olivine at relatively high (<1150?°C) subsolidus temperatures. The primary oxide is inferred to be an aluminous titanomagnetite. Similar to other layered intrusions in the region, the gabbroic unit of the BIC displays Zr depletion which is consistent with loss of a residual liquid during magma differentiation. If the most Zr-rich syenites of the complex are taken into account, the Zr budgets between the combined gabbro-syenite and the basalts are similar. This indicates that the BIC most likely represents a closed system in terms of magma extraction.  相似文献   

PRELIMINARY STUDY ON THE ENSO SIGNAL RECORDED BY THE δ18O SERIES OF ICE CORE FROM MIAOERGOU FLAT-TOPPED GLACIER,EASTERN TIENSHAN     

Zhang Yancheng  Hou Shugui  Liu Yaping  Pang Hongxi 《第四纪研究》2012,32(1)

基于东天山庙尔沟冰芯1953～2004年的δ18O序列,利用冰芯钻取点附近的气象站观测资料、NCEP/NCAR再分析数据等资料,初步分析了庙尔沟冰芯δ18O序列与ENSO事件之间的关系.研究表明,庙尔沟冰芯δ18O年序列与当年10月至次年3月间的热带太平洋东部地区(约170°～80°W)海表温度、亚洲西风气流500mb纬向风速及当年7～12月的ENSO指数之间均存在显著负相关.另外,ENSO事件对古里雅冰芯、马兰冰芯及庙尔沟冰芯δ18O序列的影响与其对达索普冰芯及Sajama冰芯δ18O序列的影响明显不同,说明ENSO事件对不同气候区冰芯δ18O序列的影响机制可能存在差异.  相似文献   

塔里木盆地塔中低凸起中古43井区碳酸盐岩油气属性分布特征及成藏模式     

汪文基  韩杰  庞雄奇  潘文庆  吴美珍  张敏 《海相油气地质》2012,17(4):57-62

塔中地区中古44和中古10两条走滑断裂切割了塔中低凸起中古43井区,它们对油气输导具有控制意义。油气从中—下寒武统沿两条走滑断裂向上运移后,在下奥陶统鹰山组内向两侧输导,呈"T"字形的油气充注方式。从断裂向两侧,V/Ni值呈减小趋势,原油密度、黏度、含硫量和含蜡量等物性参数,距离断裂由近到远,均表现为逐渐变大的趋势,这些都证明油气是由走滑断裂向两侧运移的。水、油、气井的目的层海拔分别为-4 700 m以下、约-4 600～-4 500 m和-4 500 m以上;出油气层位在海拔-4500 m以上的井,平均气油比较高,在海拔-4 500 m以下的井,平均气油比较低。研究井区油气开发的连通半径平均约600 m,小于油气成藏的连通半径。在开发和成藏两种时间尺度下隔挡层的物性上限有着显著差别。  相似文献   

Energy Transfer Mechanism and Probability Analysis of Submarine Pipe Laterally Impacted by Dropped Objects     

梁静  余建星  余杨  W. Lam  赵羿羽  段晶辉 《海洋工程》2016,(3):319-328

Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation.  相似文献   

水泥生产碳排放的产生环节及减排措施     

逄思宇  曹烨 《化工矿产地质》2014,(4):250-254

在工业生产过程中,CO2的大量排放被认为是导致气候变暖的重要因素之一,因此控制和减少CO2排放已成为人类社会面临的紧迫任务。水泥工业是人为排放CO2的重要来源之一,这就意味着水泥工业会在一种不断增加的管理压力下减少CO2的排放量,以应对全球变暖的现状。水泥生产过程中CO2的直接排放和间接排放两大排放途径,直接排放主要包括碳酸盐分解,烧成燃料/非烧成燃料的燃烧。间接排放主要是指电力消耗所产生的CO2。针对碳的排放环节,有效可行的CO2减排措施,例如原料、燃料的替代,熟料化学成分的改变,能源效率的提高等,对我国水泥工业的碳减排提出一些建议和看法。  相似文献