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水分非饱和条件下土壤矿物界面有毒有机物转化机制研究进展
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作者 程鹏飞 赵旭强 +1 位作者 秦超 高彦征 《土壤学报》 CAS CSCD 北大核心 2024年第3期594-606,共13页
土壤矿物作为土壤重要活性组分,可驱动土壤有毒有机物化学转化,降低污染风险。以往土壤矿物与有毒有机物界面行为研究主要集中于水环境或矿物悬浊液体系,然而实际环境中土壤及其矿物常处于干燥、湿润等水分非饱和状态。近年来,水分非饱... 土壤矿物作为土壤重要活性组分,可驱动土壤有毒有机物化学转化,降低污染风险。以往土壤矿物与有毒有机物界面行为研究主要集中于水环境或矿物悬浊液体系,然而实际环境中土壤及其矿物常处于干燥、湿润等水分非饱和状态。近年来,水分非饱和条件下土壤矿物界面有毒有机物转化及机制已成为研究热点,相关研究获得一系列新发现。低含水量铁锰矿物、黏土矿物和金属离子饱和黏土矿物能驱动多环芳烃、抗生素等疏水性有毒有机物化学转化。水分非饱和环境会减弱矿物界面水分子与有毒有机物竞争活性位点,并使矿物发生脱水、向高活性结构转变。此外,土壤矿物水分状态也会影响有毒有机物转化产物,水分非饱和环境更有利于持久性自由基和卤代二英等中间产物的形成和稳定。以往研究认为,电子转移反应是土壤矿物界面有毒有机物转化机制,随着检测技术与理论计算的发展,自由基催化和水解作用机制逐渐被发现,相关机制研究精准至矿物晶型和晶面层面。虽然水分非饱和条件下土壤矿物界面有毒有机物转化及机制已逐渐清晰,但其研究广度和深度有待进一步拓宽和加深。建议未来在实际水分非饱和土壤和矿物中开展有毒有机物转化研究,深入探究还原转化过程,研发原位反应装置及检测方法,尝试从微纳米尺度和分子水平解析有毒有机物在矿物界面转化机制。 展开更多
关键词 水分非饱和条件 有毒有机物 黏土矿物 铁锰矿物 转化
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基于IEEE 802.11的非饱和条件自适应接入方案 被引量:1
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作者 石春 何书前 邓正杰 《计算机工程与应用》 CSCD 2014年第22期17-21,共5页
调整参数以适应动态的网络环境,提供非饱和条件下的自适应接入方案,是无线局域网通信的研究热点。基于信道状态信息,设计线性调整接入参数规则,提出非饱和条件自适应接入方案。节点首先感知并统计信道繁忙状态数据,然后采用线性方式调... 调整参数以适应动态的网络环境,提供非饱和条件下的自适应接入方案,是无线局域网通信的研究热点。基于信道状态信息,设计线性调整接入参数规则,提出非饱和条件自适应接入方案。节点首先感知并统计信道繁忙状态数据,然后采用线性方式调整竞争窗口大小,能有效降低信道碰撞概率,提高网络性能。方案中接入参数调整体现了信道拥塞状态,解除了接入参数调整对于数据传输状态的依赖,取消了固定竞争窗口范围对性能的影响。仿真结果进一步验证算法有效性和良好的可扩展性能。 展开更多
关键词 IEEE 802.11 媒介访问控制 非饱和条件 退避算法 信道状态信息
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交叉口非饱和条件下的双向绿波交通实现方法 被引量:1
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作者 王鹏飞 房媛 《科技资讯》 2012年第11期211-212,共2页
为了缓解城市主干道的交通拥挤,本文提出一种可在交叉口非饱和条件下实施的信号协调控制方法。其中对相位差、绿波带宽度、公用周期长度三个重要参数进行了设计;并且对车速、交通量的测定方法以及控制系统的实现方法进行了描述。
关键词 交通拥挤 交叉口 非饱和条件 绿波交通
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Debris Flows Introduced in Landslide Deposits under Rainfall Conditions:The Case of Wenjiagou Gully 被引量:9
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作者 ZHOU Jia-wen CUI Peng +2 位作者 YANG Xing-guo SU Zhi-man GUO Xiao-jun 《Journal of Mountain Science》 SCIE CSCD 2013年第2期249-260,共12页
Debris flows often occur in landslide deposits during heavy rainstorms.Debris flows are initiated by surface water runoff and unsaturated seepage under rainfall conditions.A physical model based on an infinitely long,... Debris flows often occur in landslide deposits during heavy rainstorms.Debris flows are initiated by surface water runoff and unsaturated seepage under rainfall conditions.A physical model based on an infinitely long,uniform and void-rich sediment layer was applied to analyze the triggering of debris-flow introduced in landslide deposits.To determine the initiation condition for rainfall-induced debris flows,we conducted a surface water runoff and saturated-unsaturated seepage numerical program to model rainfall infiltration and runoff on a slope.This program was combined with physical modeling and stability analysis to make certain the initiation condition for rainfall-introduced debris flows.Taking the landslide deposits at Wenjiagou gully as an example,the initiation conditions for debris flow were computed.The results show that increase height of surface-water runoff and the decrease of saturated sediment shear strength of are the main reasons for triggering debris-flows under heavy rainfall conditions.The debris-flow triggering is affected by the depth of surface-water runoff,the slope saturation and shear strength of the sediment. 展开更多
关键词 Debris flow Rainfall Surface-waterrunoff Unsaturated seepage Physical modeling Numerical modeling
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Effective stress in soils under different saturation conditions 被引量:1
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作者 徐浩峰 谢康和 《Journal of Central South University》 SCIE EI CAS 2011年第6期2137-2142,共6页
BISHOP’s effective stress or two state stress variables are unsatisfactory for unsaturated soils where one of fluid phases is discontinuous, so new expressions of effective stress should be founded. The approach for ... BISHOP’s effective stress or two state stress variables are unsatisfactory for unsaturated soils where one of fluid phases is discontinuous, so new expressions of effective stress should be founded. The approach for derivation was according to the principle of equilibrium of forces (i.e., the stress-sharing principle), and it was firstly validated by demonstrating TERZAGHI’s principle of effective stress. And then, the derivations were subdivided into four parts according to different pore air states: 1) air bubbles were spherical and suspended in pore water; 2) air bubbles were bound on soil skeleton; 3) air bubbles held almost the single section of pore; 4) air phase was continuous. The different formulae of effective stress were presented. Conclusions are drawn as follows: 1) For nearly-saturated soils, the "real" effective stress would be a little smaller than TERZAGHI’s effective stress; 2) For soils in which air phase is discontinuous in the form of bubbles, a new concept of pore air elastic pressure is put forward, and the total stress can be constituted by effective stress, pore water pressure and pore air elastic pressure; 3) For soils in which air phase is continuous, effective stress is equal to the value of the total stress plus suction; 4) Suction can be divided into two parts: one is the effect caused by additional pressure, and the other is the contract action by the "skin". 展开更多
关键词 unsaturated soils effective stress SUCTION surface tension occluded gas SATURATION
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