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基于熵权水质指数方法的岩溶水质量评价及指标优化——以北京顺平岩溶水系统为例

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地质论评 2025年第1期71卷 307-316页

作者：代垠东郭高轩许亮辛宝东戚琦北京市地质环境监测所北京100195 城市地下水安全防控技术创新基地北京100195

为优化地下水水质监测方案,确定北京顺平岩溶水系统岩溶水水质的主要控制指标,快速掌握地下水水质变化,基于2022年顺平岩溶水系统49件岩溶水样品,综合运用统计分析、Piper三线图和熵权水质指数(entropy weight water quality index,EWQI... 详细信息

为优化地下水水质监测方案,确定北京顺平岩溶水系统岩溶水水质的主要控制指标,快速掌握地下水水质变化,基于2022年顺平岩溶水系统49件岩溶水样品,综合运用统计分析、Piper三线图和熵权水质指数(entropy weight water quality index,EWQI)分析研究区水化学和水质特征,并耦合逐步多元线性回归分析,探讨能代表研究区岩溶水水质的关键指标。结果显示:①顺平岩溶水系统岩溶水具有微碱性、低盐度的特征,水化学类型主要为HCO_(3)^(-)—Ca^(2+)·Mg^(2+)型(73.47%)。超标指标为N_(an)(NH_(3)或NH_(4)^(+)中的N,即氨氮以氮计)、pH值、Fe、Mn和F^(-),超标率分别为10.20%、4.08%、4.08%、4.08%和2.04%。②研究区EWQI平均值为26.33,水质“极好”,其中极好和良好所占比例分别为91.84%和8.16%。③基于地下水水质数据构建的EWQI_(min)模型筛选的关键指标为N_(an)、Fe、Mn、N_(ntr)(硝氮以氮计,硝酸盐中N)和F^(-),其决定系数(R^(2))和百分比误差(PE)分别为0.986和3.88%。表明,EWQI_(min)模型优选指标可以代表顺平岩溶水系统的水质状况,对优化水质监测网等水资源管理提供了参考价值。

关键词：顺平岩溶水系统熵权水质指数(EWQI) 逐步多元线性回归关键指标优化方法

NF_3 decomposition over Al_2O_3 reagents without water

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Journal of Natural Gas Chemistry 2011年第4期20卷 418-422页

作者： Xiufeng xu liang Sun Yanan Wang School of Chemistry and Biology Yantai University Yantai 264005 Shandong China

Several Al2O3 samples were prepared by a precipitation method coupled with ultrasonic treatment,and NF3 decomposition without water over Al2O3 reagents is carried *** effect of preparation parameters of Al2O3 reagents,such as precipitating agents,structure directing agents,and calcining temperatures on their reactivity for NF3 decomposition has been *** results show that NF3 can be decomposed completely at 400-C,and full conversion of NF3 maintains 580 min over the best Al2O3 reagent,calcined at 600-C which was prepared using both PEG-2000 and Tween-60 as structure directing agents,ammonia as a precipitating agent.

关键词： NF3 decomposition without water Al2O3 preparation parameters reactivity

Morphology and electrical contact properties of electrical connection materials in corrosive atmosphere

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Rare Metals 2013年第2期32卷 174-178页

作者： Zhi-Gang Kong liang-Jun xu Research Laboratory of Electrical Contacts Beijing University of Posts and Telecommunications

The impact mechanism of environmental fac tors, such as corrosive atmosphere, on connector materials was investigated, and the porosity of gold plating was tested. Series of inspections and analytical research meth ods were introduced in this article. The surface morphology of specimens after corrosion was observed by stereoscopic microscope and scanning electron microscope. Chemical constitution was examined by Xray energy spectrum. The contact resistances were measured by fourpoint method. The experiment results show that after exposure to certain environment, the corrosion products, such as Cu20, Cu（NO3）2.3H20, and NiO, are observed on the surface of the specimens without gold coatings, whereas the corrosion products appear to have circleshaped spots on goldplating surface after corrosion test, which indicate that the gold plating has good corrosion protection. The porosity is increased with the increase of corrosion time for every kind of specimens gold plated, and the corrosion degree of gold plating specimens is decreased with the increase of the thickness of gold coatings. The static contact resistances of circleshaped spots appear higher contact resistance than normal value, which can reach to 2,000 mr2 nearly. It is found that the high and unstable contact resistance of the pore and products is more likely to cause contact failure.

关键词： Electrical contact Porosity Corrosion Temperature

3D Modeling and Simulation of Dendritic Growth during Solidification

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Journal of Materials Science & Technology 2003年第z1期19卷 1-4页

作者： Zuojian liang Qingyan xu Baicheng LIU Department of Mechanical Engineering Tsinghua University Beijing 100084 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

A mathematical model for the three-dimensional simulation of free dendritic growth and microstructure evolutionwas developed based on the growth mechanism of crystal grains and basic transfer equations such as heat, massand momentum transfer equations. Many factors including constitutional undercooling, curvature undercooling andanisotropy, which had vital influences on the microstructure evolution, were considered in the model. Simulated resultsshowed that final microstructural patterns and free dendritic growth could be predicted reasonably and calculatedresults were coincident with experimental The simulated results of free dendritic growth indicated that the strength ofanisotropy has significant effects on free dendritic growth, dendrite profile, micro solute and temperature *** dendritic grain profiles with fully-grown parallel secondary arm tend to be formed at the intensive anisotropy,while near octahedral grain profiles with small protuberances of surface at low strength of anisotropy. The simulatedresults of free dendritic growth also indicated that there are small molten pools left in interdendritic areas. This ishelpful to understand the fundamental of the formation of microstructure related defects such as microsegregationand microporosity.

关键词： Modeling and simulation, Dendritic grain growth, Microstructure evolution

Effects of Ca(Y)-Si modifier on interface morphology and solute segregation during directional solidification of an austenite medium Mn steel

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Journal of University of Science and Technology Beijing 2005年第4期12卷 335-339页

作者： Gaofei liang Zhenming xu Jianguo Li School of Environmental Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

The austenite medium Mn steel modified with controlled additions of Ca, Y, Si were directionally solidified using the vertical Bridgman method to study the effects of Ca（Y）-Si modifier on the solid-liquid （S-L） interface morphology and solute segregation. The interface morphology and the C and Mn segregation of the steel directionally solidified at 6.9 μtrn/s were investigated with an image analysis and a scanning electron microscope equipped with energy dispersive X-ray analysis. The 0.5wt% Ca-Si modified steel is solidified with a planar S-L interface. The interface of the 1.0wt% Ca-Si modified steel is similar to that of the 0.5wt% Ca-Si modified steel, but with larger nodes. The 1.5wt% Ca-Si modified steel displays a cellular growth parttern. The S-L interface morphology of the 0.5wt% Ca-Si＋1.0wt% Y-Si modified Mn steel appears as dendritic interface, and primary austenite dendrites reveal developed lateral branching at the quenched liquid. In the meantime, the independent austenite colonies are formed ahead of the S-L interface. A mechanism involving constitutional supercooling explains the S-L interface evolution. It depends mainly on the difference in the contents of Ca, Y, and Si ahead of the S-L interface. The segregation of C and Mn ahead of the S-L interface enhanced by the modifiers is observed.

关键词： austenite Mn steel modification solid-liquid (S-L) interface morphology solute segregation directional solidification

Effect of temporal variation rate of cross polar cap potential on the equatorial ionospheric vertical drift: A statistical study

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Science China(Technological Sciences) 2012年第5期55卷 1217-1223页

作者： XIONG Wen xu JiSheng WANG Hui xu liang School of Electronic Information Wuhan UniversityWuhan 430079China

Based on the equatorial vertical ion drift measured by DMSP and cross polar cap potential （Фcpc） from AMIE output during 2001 to 2003, this paper investigates the relationship of Фcpc and its temporal variation rate （△Фcpc） with the disturbed ion velocity （△Vx） which is the difference between the disturbed days （Kp〉4） and quiet days （Kp〈2）. The statistical analysis shows：（1） The △Vx correlates better with AФcpc than with Фcpc, indicating that the electric field penetration is more easily to occur when solar wind input rapidly varies with time. （2） The optimal delay time of electric field penetration from the high-latitude magnetosphere to equatorial ionosphere has local time dependence which is longer on the nightside than on the dayside. It may be due to more complicated electrodynamic process on the nightside. （3） With the linear relationship between △Фcpc and △Vx, it is obtained that the penetration efficiency is about 4.5%-13.9% at day and 31%-42% at night, coinciding well with former studies.

关键词： equatorial ionosphere temporal variation rate of cross polar cap potential electric field penetration ion vertical drift time delay

Global ionospheric TEC response to a strong magnetic storm

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Science China(Technological Sciences) 2008年第10期51卷 1786-1802页

作者： xu liang CHENG GuangHui xu JiSheng LIU YongMin School of Electronic Information Wuhan UniversityWuhan 430079China

The global characteristics of the ionospheric storm and irregularities as well as propagation of TEC (total electron content) disturbances during the strong mag-netic storm occurring in November 2004 were investigated by using the data of the IGS network. For the response of the global ionospheric TEC to this strong mag-netic storm, the following features are noticeable: 1) the maximum of the iono-spheric storm phase occurred around the main phase maximum of the magnetic storm; 2) the TEC response in equatorial and low latitudes was more remarkable than that in mid-high latitudes; 3) as a whole, the storm phase in the northern hemisphere was mainly positive, and it was negative in the southern hemisphere; 4) during the whole magnetic storm from November 7 to 11, the locations where the maxima of the positive and negative ionospheric storm phases occurred were nearly invariant to the Sun at low and equatorial latitudes, i.e. the 24-h recurrence. Analyzing results of TEC rate and its standard deviation showed that the iono-spheric irregularities and disturbances in the global mainly occurred around the main phase maximum of the storm, and they distributed in a large longitudinal re-gion for both day and night in mid-high latitudes and they generated and developed only after the sunset, and lasted out to the midnight in equatorial and low latitudes. The disturbance propagation parameters were also estimated by using the wavelet reconstruction and cross-correlation technologies for a set of spaced stations in the Northern America.

关键词： ionosphere magnetic storm ionospheric storm irregularity IGS network TEC

Ghost-Fluid-Based Sharp Interface Methods for Multi-Material Dynamics:A Review

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Communications in Computational Physics 2023年第8期34卷 563-612页

作者： liang xu Tiegang Liu China Academy of Aerospace Aerodynamics Beijing 100074China LMIB and School of Mathematical Sciences Beihang UniversityBeijing 100191China

The ghost fluid method(GFM)provides a simple way to simulate the interaction of immiscible ***,the modified GFM(MGFM)and its variants,based on the solutions of multi-material Riemann problems,are capable of faithfully taking into account the effects of nonlinear wave interaction and material property near the *** treatments for ghost fluid states or interface conditions have been shown to be crucial when applied to various interfacial phenomena involving large discontinuity and strong *** methods,therefore,have great potential in engineering *** this paper,we review the development of such *** methodologies of representative GFM-based algorithms for definition of interface conditions are illustrated and compared to each *** research progresses in design principle and accuracy analysis are briefly *** steps and techniques for multi-dimensional extension are also *** addition,we present some progresses in more challenging scientific problems,including a variety of fluid/solid-fluid/solid interactions with complex physical *** course the challenges faced by researchers in this field are also discussed.

关键词： Multi-material flows sharp-interface method ghost fluid method modified ghost fluid method fluid-solid interaction multi-material Riemann problem

Optimal Error Estimation of the Modified Ghost Fluid Method

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Communications in Computational Physics 2010年第7期8卷 403-426页

作者： liang xu Tiegang Liu LMIB and School of Mathematics and Systems Science Beijing University of Aeronautics and AstronauticsBeijing 100191China

The modified ghost fluid method(MGFM)has been shown to be robust and efficient when being applied to multi-medium compressible *** this paper,we rigorously analyze the optimal error estimation of the MGFM when it is applied to the multi-fluid Riemann *** analyzing the properties of the MGFM and the approximate Riemann problem solver(ARPS),we show that the interfacial status provided by the MGFM can achieve“third-order accuracy”in the sense of comparing to the exact solution of the Riemann problem,regardless of the solution *** addition,our analysis further reveals that the ARPS based on a doubled shock structure in the MGFM is suitable for almost any conditions for predicting the interfacial status,and that the“natural”approach of“third-order accuracy”is practically less *** examples are presented to validate the conclusions made.

关键词： Modified ghost fluid method Riemann problem approximate Riemann problem solver