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Interface microstructure and properties of submerged arc brazing tin-based babbit 预览
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作者 周方明 李敬 +1 位作者 徐冬豪 石铭霄 《中国焊接:英文版》 EI CAS 2019年第2期45-49,共5页
The submerged arc brazing method was used to connect the tin-based babbit alloy with the steel matrix.The microstructure of the submerged arc brazed Babbitt interface layer on the surface of Q235B steel was analyzed b... The submerged arc brazing method was used to connect the tin-based babbit alloy with the steel matrix.The microstructure of the submerged arc brazed Babbitt interface layer on the surface of Q235B steel was analyzed by OM,SEM and EDS and the hardness properties of the joint interface layer were tested by MH-5 microhardness tester.the result of research shows that a layer of canine-shaped intermetallic compound with uneven thickness is formed at the interface,and the thickness is 10–20μm.The interface layer includes two kinds of compound layers,namely the FeSn layer near the side of the steel substrate and FeSn2 layer near the side of the babbit.During the interfacial reaction process,Fe atoms in the steel matrix dissolve into the liquid babbit alloy and form a certain concentration gradient at the interface.The farther from the interface,the lower the Fe atom concentration.The growth of Gibbs free energy of FeSn is lower when the temperature is above 780.15 K,and the temperature during the welding process is much higher than 780.15 K,moreover the precipitation temperature of FeSn is higher.Therefore,in the subsequent cooling process,FeSn is first precipitated from the interface near the side of steel matrix and then FeSn2 is precipitated from the interface near the side of babbit alloy.Microhardness test showed that the intermetallic compound at the interface layer significantly improved the hardness properties. 展开更多
关键词 tin-based babbitt alloy submerged arc brazing interfacial structure intermetallic compound hardness
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Heat transfer model of two-phase flow across tube bundle in submerged combustion vaporizer
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作者 Jiajun Song Dongyan Han +2 位作者 Qinqin Xu Dan Zhou Jianzhong Yin 《中国化学工程学报:英文版》 SCIE EI CAS CSCD 2019年第3期613-619,共7页
In order to optimize the design of the submerged combustion vaporizer(SCV),an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV.Several experiments were conduc... In order to optimize the design of the submerged combustion vaporizer(SCV),an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV.Several experiments were conducted using water and CO2 as the heat transfer media in the tubes,respectively.The results indicated that hot air flux,the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho).Finally,the air flux associated factorβand height associated factorγwere introduced to propose a new hocorrelation.After verified by experiments using cold water,high pressure CO2 and liquid N2 as heat transfer media,respectively,it was found that the biggest deviation between the predicted and the experimental values was less than 25%. 展开更多
关键词 SUBMERGED COMBUSTION VAPORIZER Fluid SWEEPING tube BUNDLE TWO-PHASE flow Heat transfer coefficient Modeling
Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction 预览
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作者 Jaan H. Pu Awesar Hussain +3 位作者 Ya-kun Guo Nikolaos Vardakastanis Prashanth R. Hanmaiahgari Dennis Lam 《水科学与水工程:英文版》 EI CAS CSCD 2019年第2期121-128,共8页
In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied.In the present vegetated flow modelling,the whole flow field h... In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied.In the present vegetated flow modelling,the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water layer.Within the vegetated layer,an analysis of the mechanisms affecting water flow through flexible vegetation has been conducted.In the non-vegetated layer,a modified log-law equation that represents the velocity profile varying with vegetation height has been investigated.Based on the studied analytical model,a sensitivity analysis has been conducted to assess the influences of the drag (CD) and friction (Cf ) coefficients on the flow velocity.The investigated ranges of CD and Cf have also been compared to published values.The findings suggest that the CD and Cf values are non-constant at different depths and vegetation densities,unlike the constant values commonly suggested in literature.This phenomenon is particularly clear for flows with flexible vegetation,which is characterised by large deflection. 展开更多
关键词 ANALYTICAL model FLEXIBLE VEGETATION Flow VELOCITY FRICTION Drag SUBMERGED VEGETATION
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Experimental and Numerical Study on the Hydrodynamic Characteristics of Solitary Waves Passing Over A Submerged Breakwater 预览
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作者 ZHAO Xi-zeng CHENG Du +1 位作者 ZHANG Yi-fei LI Meng-yu 《中国海洋工程:英文版》 SCIE EI CSCD 2019年第3期253-267,共15页
In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights a... In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights and water depths. Numerical simulations are performed using a high-order finite-difference model solving Navier–Stokes (N–S) equations. The predicted water wave elevation, velocity and pressure show good agreement with experimental data, verifying the accuracy and capacity of the numerical model. Furthermore, parametric studies are conducted by numerical modelling to examine the effects of the geometrical features of submerged dike on hydrodynamic characteristics around the breakwater. 展开更多
关键词 submerged BREAKWATER SOLITARY wave CIP METHOD NAVIER-STOKES model VOF METHOD
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Effects of marine sediment on the response of a submerged floating tunnel due to p- wave incidence 预览
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作者 Heng Lin Yiqiang Xiang +1 位作者 Zhengyang Chen Ying Yang 《力学学报:英文版》 SCIE EI CAS CSCD 2019年第4期773-785,共13页
Submerged floating tunnel (SFT) is a novel type traffic structure for crossing long strait and deep lakes. To investigate the dynamic pressure acting on an SFT under compression (P) wave incidence, a theoretical analy... Submerged floating tunnel (SFT) is a novel type traffic structure for crossing long strait and deep lakes. To investigate the dynamic pressure acting on an SFT under compression (P) wave incidence, a theoretical analysis model considering marine sediment effect has been proposed. Based on displacement potential functions, the reflection and refraction coefficients of P wave in different media are derived. Numerical examples are employed to illustrate the effects of the thickness of sediment layer, the incident P wave angle, the tether stiffness and spacing, and the permeability of the sediment on the dynamic pressure loading on the SFT. The results show that dynamic pressure is related to the saturation of sediment and affected by the thickness of sediment. The partially saturated sediment will amplify the dynamic pressure loading on the SFT, and the resonance frequency increases a little with the fully saturated sediment. Besides, increasing the tether stiffness and decreasing in the tether spacing will lead to a dynamic pressure falling. Deepening the SFT position and reducing the permeability of the sediment are effective measures to reduce dynamic pressure acting on the SFT. 展开更多
关键词 SUBMERGED FLOATING TUNNEL Dynamic pressure Porous medium P-WAVE DISPLACEMENT potential function
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Experimental investigation and optimization of weld bead characteristics during submerged arc welding of AISI 1023 steel 预览
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作者 Ankush Choudhary Manoj Kumar Deepak Rajendra Unune 《Defence Technology(防务技术)》 CAS CSCD 2019年第1期72-82,共11页
Submerged arc welding(SAW),owing to its high deposition rate and high welding quality,is widely used in the fabrication of pressure vessel,marine vessel,pipelines and offshore structures.However,selection of an optimu... Submerged arc welding(SAW),owing to its high deposition rate and high welding quality,is widely used in the fabrication of pressure vessel,marine vessel,pipelines and offshore structures.However,selection of an optimum combination of welding parameters is critical in achieving high weld quality and productivity.In this work,initially,the SAWexperiments were performed using fractional factorial design to analyze the effect of direct and indirect input parameters,namely,welding voltage,wire feed rate,welding speed,nozzle to plate distance,flux condition,and plate thickness on weld bead geometrical responses viz.bead width,reinforcement,and penetration.The bead on plate technique was used to deposit weld metal on AISI 1023 steel plates.The effect of SAW input parameters on response variables were analyzed using main and interaction effects.The linear regression was used to develop the mathematical models for the response variable.Then,the multi-objective optimization of input parameters was carried out using desirability approach,genetic algorithm and Jaya algorithm.The Jaya algorithm offered better optimization results as compared to desirability approach,genetic algorithm. 展开更多
关键词 SUBMERGED ARC welding Optimization Regression GENETIC ALGORITHM Jaya ALGORITHM
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Wave Propagation in Submerged Pipe Conveying Fluid
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作者 Qing-tian Deng Zhi-chun Yang 《固体力学学报:英文版》 SCIE EI CSCD 2019年第4期483-498,共16页
A problem of wave propagation in submerged pipe conveying fluid is discussed in this paper. Three different fluid-pipe models are considered: the pipe conveying non-viscous fluid immersed in still fluid, the pipe conv... A problem of wave propagation in submerged pipe conveying fluid is discussed in this paper. Three different fluid-pipe models are considered: the pipe conveying non-viscous fluid immersed in still fluid, the pipe conveying non-viscous fluid considering hydrostatic pressure and the pipe conveying viscous fluid considering hydrostatic pressure. The Fliiggle shell model and the hydrostatic pressure considered as the static prestress are introduced for the description of pipe and external/internal fluids. The effects of steady viscous forces are obtained by using the time-mean Navier-Stokes equations, and the perturbation pressures can be determined by means of potential flow theory. The wave dispersion curves of a submerged pipe conveying fluid are obtained numerically by considering the coupling conditions. The effects of internal fluid velocity and hydrostatic pressure on phase velocity are also discussed. 展开更多
关键词 Wave propagation SUBMERGED pipe HYDROSTATIC pressure Shell theory CONVEYING FLUID VISCOUS FLUID
n-Alkyl lipid concentrations and distributions in aquatic plants and their individual δD variations
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作者 Hu LIU Zhonghui LIU +1 位作者 Cheng ZHAO Weiguo LIU 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第9期1441-1452,共12页
Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid(FA) and n-alkane distributions in aquatic plants are currently limited, greatly hindering the ... Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid(FA) and n-alkane distributions in aquatic plants are currently limited, greatly hindering the applications of their isotope geochemistry in lacustrine environments. Here, the reported n-alkyl lipid distributions of aquatic plants in globally studied lakes,together with newly obtained aquatic plant n-alkyl lipid data in Chinese lakes(Yunnan and Inner Mongolia), are used to understand their distribution characteristics. The results show that aquatic plants have predominantly mid-chain lipids(C23–C25 n-alkanes and C22–C24 FAs), differing from that of terrestrial plants(dominant by long-chain lipids), but the long-chain n-alkanes(e.g., C27 and C29) and long-chain FAs(e.g., C26 and C28) also show high abundances in most samples. Submerged plants have high concentrations of long-chain n-alkanes(avg. 47 μg g-1) and long-chain FAs(avg. 170 μg g-1), close to those in terrestrial plants, indicating that submerged plants may make large contributions of long-chain n-alkyl lipids to lake sediments, while the contributions of long-chain n-alkyl lipids derived from algae to lake sediments may be small because of their low concentrations(avg. 2 μg g-1 for n-alkanes and 9 μg g-1 for FAs). We find that lipid molecular proxies(including ACL14-32 and ATR14-18) can be reliably used to distinguish the FAs sourced from algae and other plants, and Paq′ values can be utilized to distinguish the nalkane sources between submerged plants and terrestrial plants. Aquatic plants do not have significant δD differences among different chain-length n-alkanes and FAs for each sample, suggesting that the offset between δD values of different chain-length n-alkyl lipids in lake sediments can help determine sedimentary lipid input sources and infer paleohydrological changes. 展开更多
关键词 N-ALKANES Fatty acids Hydrogen ISOTOPES ALGAE SUBMERGED plants
Numerical investigation of filling transients in small-scale pipelines with submerged outlet 预览
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作者 Ling Wang Fu-jun Wang Jing Huang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期145-151,共7页
An elastic model that combines the dead-end and the orifice at the downstream end is proposed in order to study the hydraulic transients during the rapid filling in small-scale pipelines with submerged outlet.In this ... An elastic model that combines the dead-end and the orifice at the downstream end is proposed in order to study the hydraulic transients during the rapid filling in small-scale pipelines with submerged outlet.In this model,the unsteady water flow is solved by the method of characteristics,the water-air interface is traced by a shock fitting method,and the air phase is controlled by the polytropic law.The model is validated by a filling test in a pipeline with orifice.Then the proposed model is applied to the filling transient analysis in a small-scale pipeline with submerged outlet.Finally,the effects of the submerged depth of the downstream reservoir on the filling transients are analyzed.This model provides a reasonable approximation of the submerged outlet boundary condition in small-scale pipelines. 展开更多
关键词 SMALL-SCALE pipelines rapid FILLING SUBMERGED OUTLET ELASTIC model hydraulic transients
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Synthesis of Ag and Cd nanoparticles by nanosecond-pulsed discharge in liquid nitrogen
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作者 Mahmoud Trad Alexandre Nominé +4 位作者 Natalie Tarasenka Jaafar Ghanbaja Cédric Noel Malek Tabbal Thierry Belmonte 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第2期360-368,共9页
The synthesis of CdO, Ag2O (5nm) and Ag (~20~30 nm) nano-objects is achieved simultaneously by nanosecond-pulsed discharges in liquid nitrogen between one cadmium electrode and one silver electrode. Oxidation occurs w... The synthesis of CdO, Ag2O (5nm) and Ag (~20~30 nm) nano-objects is achieved simultaneously by nanosecond-pulsed discharges in liquid nitrogen between one cadmium electrode and one silver electrode. Oxidation occurs when liquid nitrogen is fully evaporated and nanoparticles are in contact with the air. No alloy is formed, whatever the conditions, even though both elements are present simultaneously, as showed by timeresolved optical emission spectroscopy. This lack of reactivity between elements is attributed to the high pressure within the discharge that keeps each metallic vapor around the electrode it comes from. Each element exhibits a specific behavior. Cubic Cd particles, formed at 4 kV, get elongated with filamentary tips when the applied voltage reaches 7 and 10 kV. Cd wires are formed by assembly in liquid nitrogen of Cd nanoparticles driven by dipole assembly, and not by dielectrophoresis. On the contrary, silver spherical particles get assembled into 2D dendritic structures. The anisotropic growth of these structures is assumed to be due to the existence of pressure gradients. 展开更多
关键词 SPARK discharges SUBMERGED discharges timeresolved optical EMISSION SPECTROSCOPY liquid NITROGEN
Study of flow characteristics within randomly distributed submerged rigid vegetation 预览
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作者 Paromita Chakraborty Arindam Sarkar 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第2期358-367,共10页
Flow through submerged rigid vegetation has been studied both analytically and experimentally.The Reynolds stress,present in the governing equation,has been modeled using one of the turbulent stress equations,adopted ... Flow through submerged rigid vegetation has been studied both analytically and experimentally.The Reynolds stress,present in the governing equation,has been modeled using one of the turbulent stress equations,adopted in numerous cases.The adva ntage of this turbulent stress model is to replace the mixing length non linear term of the stress with a linear relatio n between stress and the velocity gradient.The velocity field and shear stress are obtained by solving the governing force balance equation numerically.A correlation,validated with the experimental results,has been developed for the relevant non-dimensional numbers. 展开更多
关键词 SUBMERGED VEGETATION REYNOLDS stress drag force STREAM WISE velocity
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Experimental and numerical study of regular waves past a submerged breakwater 预览
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作者 Bi-jin Liu Du Cheng +3 位作者 Zhao-chen Sun Xi-zeng Zhao Yong Chen Wei-dong Lin 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第4期641-653,共13页
Laboratory experiments are performed to investigate the hydrodynamics around a submerged breakwater due to regular incident waves. With an in-house code, a constrained interpolation profile (CIP)-based model is employ... Laboratory experiments are performed to investigate the hydrodynamics around a submerged breakwater due to regular incident waves. With an in-house code, a constrained interpolation profile (CIP)-based model is employed to simulate this process. The model is built on a Cartesian grid system with the Navier-Stokes equations using a CIP method for the flow solver and an immersed boundary method (IBM) is used for the treatment of the solid body boundary. A more accurate interface capturing scheme, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, is used to track the free surface. The numerical results are compared with experimental data. Reasonably good agreement is achieved in terms of the wave profiles at six measuring stations, the flow velocities at three different space locations and the pressures of eight points on the surface of the submerged breakwater. Moreover, the water mass transfer over the breakwater is discussed using a two-phase VOF model and the wave spectrum is also presented for analysis. It is indicated that the present model can accurately predict the hydrodynamic characteristics of the wave over a submerged bar. Furthermore, the experimental data in the present work can provide reliable basic data, including the wave transformations, the velocities and the dynamic pressures, for the validation of other CFD models. 展开更多
关键词 SUBMERGED BREAKWATER CIP METHOD wave TRANSFORM VOF METHOD immersed boundary METHOD
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Study on Hydrodynamic Coefficients of Double Submerged Inclined Plates 预览
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作者 WANG Ke ZHANG Zhi-qiang 《中国海洋工程:英文版》 SCIE EI CSCD 2018年第1期85-89,共5页
Added mass and damping coefficients are very important in hydrodynamic analysis of naval structures. In this paper,a double submerged inclined plates with ‘/ \’ configuration is firstly considered. By use of the bou... Added mass and damping coefficients are very important in hydrodynamic analysis of naval structures. In this paper,a double submerged inclined plates with ‘/ \’ configuration is firstly considered. By use of the boundary element method (BEM) based on Green function with the wave term, the radiation problem of this special type structure is investigated. The added mass and damping coefficients due to different plate lengths and inclined angles are obtained. The results show that: the added mass and damping coefficients for sway are the largest. Heave is the most sensitive mode to inclined angles. The wave frequencies of the maximal added mass and damping coefficients for sway and roll are the same. 展开更多
关键词 DOUBLE SUBMERGED inclined plates boundary element METHOD (BEM) added mass and damping coefficients GMRES METHOD
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Land submerged to carbonate platform by conodonts: paleoenvironment reconstruction of the western Gangdese in Tibet during Triassic 预览
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作者 Zhan-sheng Ji Jian-xin Yao +5 位作者 Gui-chun Wu Qian Sun Qiu-yuan Shi Hao Li Ji-fu He Shao-wen Zhang 《中国地质(英文)》 2018年第3期450-452,共3页
The western Gangdese in Tibet during Triassic was previously considered to be a part of the Gangdese Oldland (Zhao ZZ et al.,2001;Fig.1).If the Gangdese Oldland did exist,it means no prospect of petroleum exploration ... The western Gangdese in Tibet during Triassic was previously considered to be a part of the Gangdese Oldland (Zhao ZZ et al.,2001;Fig.1).If the Gangdese Oldland did exist,it means no prospect of petroleum exploration of the Triassic strata in western Gangdese area.Fortunately,the recent biostratigraphic progresses don’t support the existence of the Gangdese Oldland.This paper aims to briefly introduce the new paleogeographic interpretation and the reason that the western Gangdese in the Triassic was marine instead of terrigenous on the basis of the recent conodont data. 展开更多
关键词 LAND SUBMERGED western GANGDESE CARBONATE platform
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Global significance of the carbon cycle in the karst dynamic system:evidence from geological and ecological processes 预览
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作者 Jian-hua Cao Xia Wu +4 位作者 Fen Huang Bill Hu Chris Groves Hui Yang Chun-lai Zhang 《中国地质(英文)》 2018年第1期17-27,共11页
On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle proce... On the basis of proposing the existence of a karst carbon cycle and carbon sink at a watershed scale,this paper provides four pieces of evidence for;the integration of geology and ecology during the carbon cycle processes m the karst dynamic system,and estxmated the karst carbon sink effect using the methods of comparative monitoring of paired watersheds and the carbon stable isotope tracer technique.The results of the soil carbon cycle in Maocun,Guilin,showed that the soil carbon cycle in the karst area,the weathering and dissolution of carbonate rocks under the soil,resulted in a lower soil respiration of 25% in the karstoarea than in a non-karst area (sandstone and shale),and the carbon isotope results indicated that 13.46% of the heavy carbon of the hmestone is involved in the soil carbon cycle.The comparative monitoring results m paxred watersheds,suggesting that the HCO3 concentration m a karst spring is 10 times that of a rivulet in a non-karst area,while the concentration of inorganic carbon flux is 23.8 times.With both chemical stoichiometry and carbon stable isotopes,the proportion of carbon in karst springs derived from carbonate rocks was found to be 58.52% and 37.65% respectively.The comparison on carbon exchange and isotopes at the water-gas interface between the granite and carbonate rock basins in the Li River showed that the CO2 emission of the karst water is 10.92 times that of the allogenic water from the non-karst area,while the carbon isotope of HCO3^- in karst water is lighter by 8.62%.However,this does not mean that the karst water body has a larger carbon source effect.On the contrary,it means the karst water body has a greater karst carbon sink effect.When the karst subterranean stream in Zhaidi,Guilin,is exposed at the surface,carbon-rich karst water stimulated the growth of aquatic plants.The values of carbon stable isotopes in the same species of submerged plants gradually becomes heavier and heavier,and the 512 m flow process has a maximum range of 15.46%.The calculation results showe 展开更多
关键词 KARST CARBON cycle CARBON stable isotope CARBON SINK effect SUBMERGED plants GUILIN
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Flow Separation and Vortex Dynamics in Waves Propagating over A Submerged Quartercircular Breakwater 预览
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作者 JIANG Xue-lian YANG Tian +1 位作者 ZOU Qing-ping GU Han-bin 《中国海洋工程:英文版》 SCIE EI CSCD 2018年第5期514-523,共10页
The interactions of cnoidal waves with a submerged quartercircular breakwater are investigated by a Reynolds-Averaged Navier–Stokes(RANS)flow solver with a Volume of Fluid(VOF)surface capturing scheme(RANSVOF)model.T... The interactions of cnoidal waves with a submerged quartercircular breakwater are investigated by a Reynolds-Averaged Navier–Stokes(RANS)flow solver with a Volume of Fluid(VOF)surface capturing scheme(RANSVOF)model.The vertical variation of the instantaneous velocity indicates that flow separation occurs at the boundary layer near the breakwater.The temporal evolution of the velocity and vorticity fields demonstrates vortex generation and shedding around the submerged quartercircular breakwater due to the flow separation.An empirical relationship between the vortex intensity and a few hydrodynamic parameters is proposed based on parametric analysis.In addition,the instantaneous and time-averaged vorticity fields reveal a pair of vortices of opposite signs at the breakwater which are expected to have significant effect on sediment entrainment,suspension,and transportation,therefore,scour on the leeside of the breakwater. 展开更多
关键词 SUBMERGED quartercircular BREAKWATER cnoidal wave flow separation VORTEX dynamics SCOUR
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三峡水库蓄水对消落带土壤Cu、Zn、Cr、Cd含量的影响
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作者 杨丹 谢宗强 +2 位作者 樊大勇 熊高明 张爱英 《自然资源学报》 CSSCI CSCD 北大核心 2018年第7期1283-1290,共8页
为揭示水位涨落形成系列淹水梯度对消落带土壤重金属含量的影响,论文采集三峡水库忠县消落带土壤,分析了不同淹水深度土壤Cu、Zn、Cr、Cd含量,并探讨了这些重金属元素物质来源及其与三峡水库水位涨落关系。结果表明:1)不同淹水深... 为揭示水位涨落形成系列淹水梯度对消落带土壤重金属含量的影响,论文采集三峡水库忠县消落带土壤,分析了不同淹水深度土壤Cu、Zn、Cr、Cd含量,并探讨了这些重金属元素物质来源及其与三峡水库水位涨落关系。结果表明:1)不同淹水深度下消落带土壤重金属含量差异较大,长期淹水土壤Cu、Zn、Cd含量远远高于短期淹水和未淹水土壤,Cr则在不同淹水深度略有变化;2)除CrSg对独立外,不同淹水深度下土壤SOM、pH与土壤cu、Zn、Cd含量密切相关,但pH、SOM间仅有微弱的相关关系;3)因子分析中因子1和因子2对Cu、Zn、Cr、Cd的累计贡献率为93.47%,Cu、Zn、Cd在第一轴载荷值为0.962、0.967、0.925,Cr在第二轴载荷值为0.998。研究发现:1)重金属输入来源和流向异质性是决定不同淹水深度Cu、zn、Cr、Cd含量差异的重要原因,长期淹水显著增加了土壤Cu、Zn、Cd含量,但对Cr效应并不明显;2)区域土壤内cr主要来源为自然源的土壤侵蚀和母岩风化,Cu、Zn、Cd来源于人为输入的库岸输入和长江上游来水悬浮颗粒沉积,应引起足够重视。 展开更多
关键词 因子分析-多元线性回归 地球化学行为 淹水 水位调度
中国洪湖沉水植物群落调查与分析 预览
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作者 李岚晶 封瑛 《世界生态学》 2018年第2期129-141,共13页
沉水植物是指植物体全部位于水层下面固着生存的大型水生植物,是湖泊生态系统的重要组成部分,具有净化水质、提供饵料、改善生境、营造景观的多重生态功能。洪湖是中国第七大、湖北省第一大淡水湖泊,水生植物十分丰富。按照水生植物调... 沉水植物是指植物体全部位于水层下面固着生存的大型水生植物,是湖泊生态系统的重要组成部分,具有净化水质、提供饵料、改善生境、营造景观的多重生态功能。洪湖是中国第七大、湖北省第一大淡水湖泊,水生植物十分丰富。按照水生植物调查规范,2017年7月对洪湖沉水植物群落调查,发现洪湖主要建群沉水植物有6科8属15种,包括金鱼藻(Ceratophyllum demersum)、五刺金鱼藻(C. oryzetorum)、黑藻(Hydrilla verticillata)、苦草(Vallisneria natans)、水车前(Ottelia alismoides)、荇菜(Nymphoidespeltata)、金银莲花(Nymphoides indica)、狐尾藻(Myriophyllum spicatum)、轮叶狐尾藻(M. verticillatum)、菹草(Potamogeton cristatus)、光叶眼子菜(P. lucens)、微齿眼子菜(P. maackianus)、竹叶眼子菜(P. malaianus)、蓖齿眼子菜(P. pectinatus)和小眼子菜(P. pusillus)。沉水植物组成了7个群丛48个群落,覆盖了洪湖49.14%的面积。分析表明,1960年代洪湖主要优势沉水植物是耐污能力差、饵料价值高的竹叶眼子菜、苦草和黑藻,表明那时的洪湖水质清洁,鱼类饵料丰富、生态系统优良;1980年代,耐污能力强的微齿眼子菜、菹草和金鱼藻占据优势,1990年代一直维持着这个格局,表明1980~2000期间,洪湖水质比较差;本次调查显示,虽然优势沉水植物还是耐污能力比较强的菹草和篦齿眼子菜,但苦草和竹叶眼子菜又重新回到优势种的位置,表明洪湖局部地区水质开始好转,生态健康程度有所回升。为提高生态系统稳定性,建议进一步取缔围网、绞草、拖螺等人为干扰,同时改善入湖水质,增加水体透明度,促进沉水植物的恢复。 展开更多
关键词 沉水植物 生态系统 植物群落 生物多样性 洪湖 SUBMERGED PLANT ECOSYSTEM PLANT Community BIODIVERSITY Honghu Lake
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百年一遇潮位淹没影响下山东沿海地区经济脆弱性评价 预览
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作者 李梦梦 罗新正 《海洋通报》 CSCD 北大核心 2018年第6期667-675,共9页
经济发达的山东沿海局部地区地势低平,海堤多为五十年一遇标准,一旦发生百年一遇风暴潮淹没事件,将会带来巨大的经济损失。因此,对山东沿海地区经济脆弱性进行评价,有助于减灾防灾措施的实施。本文借助DEM、遥感数据和GIS评价百年一遇... 经济发达的山东沿海局部地区地势低平,海堤多为五十年一遇标准,一旦发生百年一遇风暴潮淹没事件,将会带来巨大的经济损失。因此,对山东沿海地区经济脆弱性进行评价,有助于减灾防灾措施的实施。本文借助DEM、遥感数据和GIS评价百年一遇潮位淹没影响下山东沿海地区经济脆弱性。研究结果如下:百年一遇潮位淹没影响范围主要集中在潍坊、东营和滨州;龙口、福山、芝罘、莱山、威海四市、临胶州湾各区与日照沿海的东港区和岚山区GDP密度较高,滨州、东营、潍坊各市、区,莱州、招远、蓬莱、牟平、海阳、莱阳、即墨与平度的GDP密度较低;淹没深度较大地区集中在潍坊,东营部分地区,胶州湾及日照沿海地区;结果表明:(1)经济脆弱性极高地区分布在寒亭区,城阳区;经济脆弱性很高地区为黄岛区;经济脆弱性为高的地区有东港区、莱州市、寿光市、昌邑县、广饶县与东营区等地;(2)脆弱性成因:寒亭区、寿光市、昌邑县、广饶县、东营区、莱州市、县是淹没面积大,淹没深度大;黄岛区、东港区及城阳是GDP密度大,淹没深度大;(3)预防风暴潮灾害可通过加强预警预报与应急预案建设,调整经济分布,加强柽柳湿地保护与积极扩大柽柳湿地范围等方法。 展开更多
关键词 百年一遇潮位 山东沿海地区 GDP 脆弱性评价 淹没
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浸水条件地震主动土压力的改进拟动力法 预览
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作者 黄睿 《绍兴文理学院学报》 2017年第8期1-7,共7页
基于极限平衡分析和拟动力法的计算思路,以无粘性填土的刚性挡土墙为研究对象,考虑填土处于无渗流的完全浸水条件,推导给出了浸水挡墙地震主动土压力的改进拟动力法的计算表达式.通过程序求解和参数分析表明:浸水条件下,拟动力法中的... 基于极限平衡分析和拟动力法的计算思路,以无粘性填土的刚性挡土墙为研究对象,考虑填土处于无渗流的完全浸水条件,推导给出了浸水挡墙地震主动土压力的改进拟动力法的计算表达式.通过程序求解和参数分析表明:浸水条件下,拟动力法中的剪切波参数对土压力系数的影响胜于压缩波参数,计算所得的土压力曲线为"类S型";主动土压力值随内摩擦角的增大而显著减小,随水平地震加速度的增大而明显增大,竖向地震加速度对土压力影响较小,可以忽略不计.与干土的地震主动土压力对比,浸水后土压力系数有一定增大,并且两者的差异随着地震作用的增大而扩大. 展开更多
关键词 土压力 地震 浸水 拟动力法
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