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Retention and Mobility of Copper and Lead in Soils as Influenced by Soil Horizon Properties

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Pedosphere 2011年第5期21卷 603-614页

作者： B.CeRQUeIRA e.f.COVeLO M.L.ANDRADe f.A.VeGA Department of Plant Biology and Soil Science University of Vigo

The mobility and bioavailability of heavy metals in soils is largely governed by sorption and desorption ***2+ and Pb2+ are among the most potentially toxic heavy metals and they are present,often concomitantly,in many polluting spills and in *** objective was to assess and compare the competitive sorption and desorption capacities and sorption hysteresis of Cu2+ and Pb2+,as well as their migration through the profiles of four natural soils:a Humic Umbrisol,an Umbric Cambisol,an endoleptic Luvisol and a Humic *** all horizons Pb2+ was invariably sorbed and retained to a greater extent than Cu2+.The sorption and retention of Cu2+ were most in?uenced by pH,e?ective cation exchange capacity(CeCe) and Mn oxide *** the other hand,the fixation capacity of Pb2+ was most in?uenced by pH,CeCe,and Mn oxide and organic matter *** and CeCe were the individual soil properties most markedly in?uencing Cu2+ and Pb2+ sorption and *** all the horizons Pb2+ exhibited greater hysteresis than Cu2+.In each soil the hysteresis in the A horizon was greater than that in the B horizon,except in the Bt horizon of the endoleptic Luvisol,due to its high pH and vermiculite *** on migration indices,Pb2+ was less mobile than Cu2+ in the studied soils.

关键词： desorption heavy metal hysteresis migration sorption

Discrete modeling of a longwall coal mine gob for CfD simulation

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International Journal of Mining Science and Technology 2020年第4期30卷 463-469页

作者： Aditya Juganda Claire Strebinger Jurgen f.Brune Gregory e.Bogin Colorado School of Mines GoldenCO 80401USA

One area of concern in longwall coal mines is the active gob directly behind the longwall face,where high concentrations of methane are likely to accumulate and active roof caving *** computational fluid dynamics(CfD)to simulate gas flows in and through the gob,most researchers have represented the entire gob as a porous medium governed by Darcy’s ***,Darcy-type porous flow may not be applicable for the highly porous and unconsolidated fringes of the *** addition,porous medium models do not allow for representative combustion modeling to simulate in-gob ignition and flame *** study presents a hybrid approach to modeling the gob using CfD:the outer part of the gob is modeled as discrete objects that simulate coarse rock rubble,while the gob center is modeled as a porous medium.

关键词： Longwall Coal Computational fluid dynamic Modeling Ventilation

Discrepancies between targets and achievements in industrial forest production and export in Tanzania

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forestry Studies in China 2012年第3期14卷 210-215页

作者： e.f.NZUNDA Department of forest Mensuration and Management Chuo Kikuu 3013MorogoroTanzania

It is important to revisit our plans and compare what was ideally targeted against what was actually achieved in implementation. In comparing the achievements with targets, strengths or weaknesses of established strategies can be accepted or corrections implemented since a plan also outlines some strategies for achieving the targets set. In this study, achievements in production and export of industrial forest products, i.e., sawn wood, plywood, chipboard and fibreboard, paper and paperboard and industrial round wood, are compared against targeted figures for 1996 for Tanzania. Discrepancies were obtained by subtracting targeted from achieved values and expressed both as absolute and relative differences in terms of the targeted values, with a negative sign for pro- duction where achievements were less than targets and a positive sign when achievements were higher than targets. Values achieved ranged from 4%-100% of the targeted values, depending on the product, and were only higher than the targeted value for industrial round wood. Possible causes of the discrepancies are inefficiency of parastatal companies, low private investment, sub-maximal in- dustrial operation and plant inefficiencies. Discrepancies could also result from unrealistic data used in planning due to difficulty in data availability and poor intra- and inter-sectoral coordination. The implications of these discrepancies are low contributions of the wood-based industry to the national economy, increased import substitution of wood-based products, increased socio-economic and environmental degradation and decreased integrity in planning and policy making.

关键词： targets achievements industrial forest production and export Tanzania

The shifts of precipitation phases and their impacts

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Science China earth Sciences 2025年

作者： Xuemei LI Tao CHe Yuanlong TANG Huan'e DUAN Guigang WANG Xu ZHANG Chuanming YANG Jun WU Yue ZHANG Lanhai LI faculty of Geomatics Lanzhou Jiaotong University National-Local Joint engineering Research Center of Technologies and Applications for National Geographic State Monitoring Key Laboratory of Science and Technology in Surveying & Mapping Gansu Province Key Laboratory of Cryospheric Science and frozen Soil engineering Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Xinjiang Key Laboratory of Water Cycle and Utilization in Arid Zone Xinjiang Institute of Ecology and Geography Chinese academy of Sciences Tianshan Snow Cover and Avalanche Observation and Research Station of Xinjiang

Precipitation comes in various phases, including rainfall, snowfall, sleet, and hail. Shifts of precipitation phases, as well as changes in precipitation amount, intensity, and frequency, have significant impacts on regional climate, hydrology,ecology, and the energy balance of the land-atmosphere system. Over the past century, certain progress has been achieved in aspects such as the observation, discrimination, transformation, and impact of precipitation phases. Mainly including:since the1980s, studies on the observation, formation mechanism, and prediction of precipitation phases have gradually received greater attention and reached a certain scale. The estimation of different precipitation phases using new detection theories and methods has become a research focus. Avariety of discrimination methods or schemes, such as the potential thickness threshold method of the air layer, the temperature threshold method of the characteristic layer, and the near-surface air temperature threshold method,have emerged one after another. Meanwhile, comparative studies on the discrimination accuracy and applicability assessment of multiple methods or schemes have also been carried out simultaneously. In recent years, the shift of precipitation from solid to liquid (SPSL) in the mid-to-high latitudes of the Northern Hemisphere has become more pronounced due to global warming and human activities. It leads to an increase in rain-on-snow (ROS) events and avalanche disasters, affecting the speed, intensity, and duration of spring snow-melting, accelerating sea ice and glacier melting, releasing carbon from permafrost, altering soil moisture, productivity, and phenological characteristics of ecosystems, and thereby affecting their structures, processes, qualities, and service functions. Although some progress has been made in the study of precipitation phases, there remains considerable research potential in terms of completeness of basic data, reliability of discrimination schemes,

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基于JPDf方法的喷雾湍流燃烧数值模拟

农业机械学报 2010年第7期41卷 6-10页

作者：何志霞王谦 Andriy Rybakov Ulrich maas 江苏大学能源与动力工程学院镇江212013 卡尔斯鲁厄大学热力技术研究所

将速度-标量-频率联合概率密度函数JPDf输运方程方法应用于两相喷雾湍流反应流问题,利用火焰面模型解耦流动和化学反应动力学的耦合关系,建立相应的数值计算模型。采用Monte-Carlo数值计算方法,针对文献中以甲醇为燃料所进行的湍流喷雾... 详细信息

将速度-标量-频率联合概率密度函数JPDf输运方程方法应用于两相喷雾湍流反应流问题,利用火焰面模型解耦流动和化学反应动力学的耦合关系,建立相应的数值计算模型。采用Monte-Carlo数值计算方法,针对文献中以甲醇为燃料所进行的湍流喷雾燃烧值班火焰这一试验进行了数值模拟,通过与fluent下的计算结果及试验结果的对比分析,验证了所建模型的准确性。

关键词：喷雾湍流燃烧联合概率密度函数小火焰面模型数值模拟

Modeling of nonlinear envelope solitons in strongly coupled dusty plasmas:Instability and collision

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Chinese Physics B 2015年第3期24卷 237-247页

作者： S.K.el-Labany e.f.el-Shamy W.f.el-Taibany N.A.Zedan Department of Physics Faculty of ScienceDamietta University Department of Physics College of ScienceKing Khalid University Department of Physics College of Science for Girls in AbhaKing Khalid University

Modeling of instability and collision of nonlinear dust-acoustic（NDA） envelope solitons in strongly coupled dusty plasmas（SCDPs） is theoretically investigated. The SCDPs consists of strongly correlated negatively variable-charged dust grains and weakly correlated Boltzmann electrons and ions. Using the derivative expansion perturbation technique, a nonlinear Schr dinger-type（NLST） equation for describing the propagation of NDA envelope solitons is derived. Moreover,the extended Poincar′e–Lighthill–Kuo（ePLK） method is employed to deduce the analytical phase shifts and the trajectories after the collision of NDA envelope solitons. In detail, the results show that both modulation instability and phase shift after collision of NDA envelope solitons will modify with the increase in the effects of the viscosity, the relaxation time, and the dust charge fluctuation. Crucially, the modeling of dust-acoustic envelope solitons collision, as reported here, is helpful for understanding the propagation of NDA envelope solitons in strongly coupled dusty plasmas.

关键词： dust acoustic wave envelopes modulational instability head-on collision polarization effects

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甲醇喷雾湍流反应流的JPDf数值模拟

工程热物理学报 2011年第3期32卷 533-536页

作者：何志霞王谦 RYBAKOV Andriy maas Ulrich 江苏大学能源与动力工程学院江苏镇江212013 卡尔斯鲁厄大学热力技术研究所卡尔斯鲁厄德国76128

喷雾湍流燃烧过程中,液滴、湍流和化学反应之间强烈耦合,物理化学机理非常复杂。本文将速度-标量-频率联合概率密度函数JPDf输运方程方法应用于两相喷雾湍流反应流问题,利用火焰面模型解耦流动和化学反应动力学的耦合关系,建立起相应的... 详细信息

喷雾湍流燃烧过程中,液滴、湍流和化学反应之间强烈耦合,物理化学机理非常复杂。本文将速度-标量-频率联合概率密度函数JPDf输运方程方法应用于两相喷雾湍流反应流问题,利用火焰面模型解耦流动和化学反应动力学的耦合关系,建立起相应的数值计算模型。采用Monte-Carlo数值计算方法,针对澳大利亚悉尼大学Masri等人以甲醇为燃料所进行的湍流喷雾燃烧值班火焰这一试验进行了数值模拟,通过与fluent下的计算结果及试验结果的对比分析,验证了本文所建模型的准确性。

关键词：甲醇喷雾湍流反应流联合概率密度函数法JPDf 小火焰面模型数值模拟

Operator Splitting for Three-Phase flow in Heterogeneous Porous Media

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Communications in Computational Physics 2009年第6期6卷 72-84页

作者： e.Abreu J.Douglas f.furtado f.Pereira Instituto Nacional de Matematica Pura e Aplicada RJ 22460-320Brazil Department of Mathematics Purdue UniversityWest LafayetteIN 47907-1395USA Department of Mathematics University of WyomingLaramieWY 82071-3036USA Department of Mathematics and School of energy Resources University of WyomingLaramieWY 82071-3036USA

We describe an operator splitting technique based on physics rather than on dimension for the numerical solution of a nonlinear system of partial differential equations which models three-phase flow through heterogeneous porous *** model for three-phase flow considered in this work takes into account capillary forces,general relations for the relative permeability functions and variable porosity and permeability *** our numerical procedure a high resolution,nonoscillatory,second order,conservative central difference scheme is used for the approximation of the nonlinear system of hyperbolic conservation laws modeling the convective transport of the fluid *** scheme is combined with locally conservative mixed finite elements for the numerical solution of the parabolic and elliptic problems associated with the diffusive transport of fluid phases and the pressure-velocity *** numerical procedure has been used to investigate the existence and stability of nonclassical shock waves(called transitional or undercompressive shock waves)in two-dimensional heterogeneous flows,thereby extending previous results for one-dimensional flow *** experiments indicate that the operator splitting technique discussed here leads to computational efficiency and accurate numerical results.

关键词： Operator splitting three-phase flow heterogeneous porous media central differencing schemes mixed finite elements

Capsule endoscopy:Current practice and future directions

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World Journal of Gastroenterology 2014年第24期20卷 7752-7759页

作者： Melissa f Hale Reena Sidhu Mark e McAlindon Department of Gastroenterology Royal Hallamshire HospitalSheffield S10 2JFUnited Kingdom

Capsule endoscopy (Ce) has transformed investigation of the small bowel providing a non-invasive, well tolerated means of accurately visualising the distal duodenum, jejunum and ileum. Since the introduction of small bowel Ce thirteen years ago a high volume of literature on indications, diagnostic yields and safety profile has been presented. Inclusion in national and international guidelines has placed small bowel capsule endoscopy at the forefront of investigation into suspected diseases of the small bowel. Most commonly, small bowel Ce is used in patients with suspected bleeding or to identify evidence of active Crohn’s disease (CD) (in patients with or without a prior history of CD). Typically, Ce is undertaken after upper and lower gastrointestinal flexible endoscopy has failed to identify a diagnosis. Small bowel radiology or a patency capsule test should be considered prior to Ce in those at high risk of strictures (such as patients known to have CD or presenting with obstructive symptoms) to reduce the risk of capsule retention. Ce also has a role in patients with coeliac disease, suspected small bowel tumours and other small bowel disorders. Since the advent of small bowel Ce, dedicated oesophageal and colon capsule endoscopes have expanded the fields of application to include the investigation of upper and lower gastrointestinal disorders. Oesophageal Ce may be used to diagnose oesophagitis, Barrett’s oesophagus and varices but reliability in identifying gastroduodenal pathology is unknown and it does not have biopsy capability. Colon Ce provides an alternative to conventional colonoscopy for symptomatic patients, while a possible role in colorectal cancer screening is a fascinating prospect. Current research is already addressing the possibility of controlling capsule movement and developing capsules which allow tissue sampling and the administration of therapy.

关键词： Capsule endoscopy Small bowel Indications Technology Oesophageal Colon