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A FINITE DIFFERENCE SCHEME FOR SOLVING THE NONlinEAR POISSON-BOLTZMANN EQUATION MODElinG CHARGED SPHERES

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Journal of Computational Mathematics 2006年第3期24卷 252-264页

作者： Zhong-hua Qiao zhi-lin li Tao Tang Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong China Center for Research in Scientific Computation and Department of Mathematics North Carolina State University Raleigh NC 27695 USA

In this work, we propose an efficient numerical method for computing the electrostatic interaction between two like-charged spherical particles which is governed by the nonlinear Poisson-Boltzmann equation. The nonlinear problem is solved by a monotone iterative method which leads to a sequence of linearized equations. A modified central finite difference scheme is developed to solve the linearized equations on an exterior irregular domain using a uniform Cartesian grid. With uniform grids, the method is simple, and as a consequence, multigrid solvers can be employed to speed up the convergence. Numerical experiments on cases with two isolated spheres and two spheres confined in a charged cylindrical pore are carried out using the proposed method. Our numerical schemes are found efficient and the numerical results are found in good agreement with the previous published results.

关键词： Nonlinear Poisson-Boltzmann equation Electrostatic interaction Irregulardomain Monotone iterative method Multigrid solver

Covalent electron density analysis and surface energy calculation of gold with the empirical electron surface model

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 676-682页

作者： Bao-qin Fu zhi-lin li Wei liu College of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China Laboratory of Advanced Materials Department of Material Science and Engineering Tsinghua University Beijing 100084 China

Based on the empirical electron surface model （EESM）,the covalent electron density of dangling bonds （CEDDB） was calculated for various crystal planes of gold,and the surface energy was calculated *** results show that CEDDB has a great influence on the surface energy of various index surfaces and the anisotropy of the *** calculated surface energy is in agreement with experimental and other theoretical *** calculated surface energy of the close-packed （111） surface has the lowest surface energy,which agrees with the theoretical ***,it is found that the spatial distribution of covalent bonds has a great influence on the surface energy of various index ***,CEDDB should be a suitable parameter to describe and quantify the dangling bonds and surface energy of various crystal surfaces.

关键词： surface energy dangling bonds covalent bonds electron density gold

A Variant Modified Skew-Normal Splitting Iterative Method for Non-Hermitian Positive Definite linear Systems

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Numerical Mathematics(Theory,Methods and Applications) 2022年第2期15卷 510-529页

作者： Rui li Jun-Feng Yin zhi-lin li College of Data Science Jiaxing UniversityZhejiang 314001P.R.China School of Mathematical Sciences Tongji UniversityShanghai 200092P.R.China Center for Research in Scientific Computation and Department of Mathematics North Carolina State UniversityRaleighNC 27695USA

We propose a variant modified skew-normal splitting iterative method to solve a class of large sparse non-Hermitian positive definite linear *** the preconditioning technique we also construct the preconditioned version of the proposed *** analysis shows that the proposed method is unconditionally convergent even when the real part and the imaginary part of the coefficient matrix are ***,when the real part and the imaginary part of the coefficient matrix are symmetric positive definite,we prove that the preconditioned variant modified skew-normal splitting iterative method will also unconditionally *** experiments are presented to illustrate the efficiency of the proposed method and show better performance of it when compared with some other methods.

关键词： Non-Hermitian matrix skew-normal splitting precondition complex linear system

SYSTEM FOR AUTOMATIC GENERAliZATION OF TOPOGRAPHIC MAPS

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Chinese Geographical Science 2006年第2期16卷 165-170页

作者： YAN Hao-wen li zhi-lin AI Ting-hua School of Mathematics Physics and Software Engineering Lanzhou Jiaotong University Lanzhou 730070 19. R. China GIS Division Department of Geography University of Zurich Zurich Switzerland Department of Land Surveying ancl Geo-lnformatics the Hong Kong Polytechnic University Hong Kong P. R. China School of Resource and Environment Science Wuhan University Wuhan 430079 P. R. China

With the construction of spatial data infi＇astructure, automated topographic map generalization becomes an indispensable component in the community of cartography and geographic information science. This paper describes a topographic map generalization system recently developed by the authors. The system has the following characteristics： 1） taking advantage of three levels of automation, i.e. fully automated generalization, batch generalization, and interactive generalization, to undertake two types of processes, i.e. intelligent inference process and repetitive operation process in generalization; 2） making use of two kinds of sources for generalizing rule library, i.e. written specifications and cartographers＇ experiences, to define a six-element structure to describe the rules; 3） employing a hierarchical structure for map databases, logically and physically; 4） employing a grid indexing technique and undo/redo operation to improve database retrieval and object generalization efficiency. Two examples of topographic map generalization are given to demonstrate the system. It reveals that the system works well. In fact, this system has been used for a number of projects and it has been found that a great improvement in efficiency compared with traditional map general- ization process can be achieved.

关键词： map generalization system map database rule library topographic map

Preparation and characterization of Fe_2O_3-CeO_2-TiO_2/γ-Al_2O_3 catalyst for degradation dye wastewater

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Journal of Environmental Sciences 2006年第6期18卷 1189-1192页

作者： liU Yan SUN De-zhi CHENG lin li Yan-ping School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150090 China

In order to develop a catalyst with high activity for catalytic wet oxidation （CWO） process at room temperature and atmospheric pressure, Fe2O3-CeO2-TiO2/γ-Al2O3 catalyst was prepared by consecutive impregnation method and the prepared parameters were optimized. The structure of the catalyst was characterized by BET, XRF, SEM and XPS technologies, and the actual wastewater was used to investigate the catalytic activity of Fe2O3-CeO2-TiO2/γ-Al2O3 in CWO process. The experimental results showed that the prepared catalyst exhibited good catalytic activity when the doping amount of Ti was 1.0 wt% （the weight ratio of Ti to carriers）, and the middle product, Fe2O3-CeO2-TiO2/γ-Al2O3, was calcined in 450℃ for 2 h. The CWO experiment for treating actual dye wastewater indicated that the COD, color and TOC of actual wastewater were decreased by 62.23%, 50.12% and 41.26% in 3 h, respectively, and the ratio of BOD5/COD was increased from 0.19 to 0.30.

关键词： catalytic wet oxidation (CWO) Fe2O3-CeO2-TiO2/γ-Al2O3 catalyst dye wastewater treatment

焦化企业周边地表水中16种多环芳烃气相色谱-质谱分析方法建立及应用

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化学研究与应用 2024年第1期36卷 211-219页

作者：刘淑娟李国文李元叶正中施艳峰普学伟李志林玉溪师范学院化学生物与环境学院云南玉溪653100 云南农业大学动物科学技术学院云南昆明650201 云南省生态环境厅驻玉溪市生态环境监测站云南玉溪653100

为实现焦化企业周边地表水中多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的检测,建立了液液萃取结合气相色谱-质谱法(GC-MS)测定16种PAHs残留的分析方法。通过优化色谱、质谱参数确定最佳分析条件,比较不同种类的提取剂(正己烷、... 详细信息

为实现焦化企业周边地表水中多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的检测,建立了液液萃取结合气相色谱-质谱法(GC-MS)测定16种PAHs残留的分析方法。通过优化色谱、质谱参数确定最佳分析条件,比较不同种类的提取剂(正己烷、二氯甲烷、二氯甲烷-正己烷混合液(V/V=1:1))及其用量、提取时间、提取次数对16种PAHs方法回收率的影响,确定最优前处理方法。取1 L水样加入20.0 g氯化钠,并用50 mL二氯甲烷提取两次,合并提取液并经无水硫酸钠脱水,定量浓缩至0.5 mL,再用二氯甲烷准确定容至1.0 mL。选用弱极性色谱柱HP-5 MS对目标物进行分离,在电子电离源(EI)模式和选择离子监测(SIM)模式下进行测定,氘代内标法定量。在最优提取条件下,16种PAHs可在37.0 min内完成色谱分离分析,在2~500μg·L^(-1)范围内线性关系良好,平均相对响应因子的相对标准偏差(RRF RSD)小于14%,方法检出限为0.003~0.01μg·L^(-1),定量限为0.02~0.04μg·L^(-1)。分别向实际水样添加3个不同质量浓度(0.01、0.05和0.25μg·L^(-1))水平进行回收试验,测得16种PAHs的平均回收率为63.0%~100.3%,相对标准偏差为0.7%~8.2%(n=6)。将该方法用于当地焦化企业周边地表水中16种PAHs残留筛查,结果显示受检的6份样品有3份不同程度检出7种PAHs单体,检出质量浓度(μg·L^(-1))较高的3种单体为苊(0.241)、芴(0.088)、荧蒽(0.075),∑_(16) PAHs总质量浓度范围为0~0.551μg·L^(-1)。研究建立的方法具有较高的选择性、正确度和灵敏度,可为调查焦化企业周边地表水中16种PAHs残留提供可靠的技术保障。

关键词：多环芳烃(PAHs) 地表水焦化企业气相色谱-质谱法(GC-MS)

In situ XRD Studies on Heat-treated PtRu/C Nanocatalysts

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Chemical Research in Chinese Universities 2012年第3期28卷 511-515页

作者： liU Juan-ying li zhi-lin VOGEL Walter YANG Hui Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 200050P.R.China Department of Chemistry National Central UniversityTaoyuan 32001TaiwanP.R.China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201203P.R.China

Extremely small PtRu/C nanocatalysts were prepared via a carbonyl route. A thorough in situ reduction X-ray structural characterization of these catalysts was performed. After synthesis and storage under ambient condi- tions, the diffraction patterns of PtRu/C catalysts were seriously modified, indicating the surface oxide formation. In the reduced state, the particle size is around 2 nm. The observed relative fluctuations of lattice constants are 3%, which is far too large to be explained by a compositional fluctuation. Their origin is attributed to strong but isotropic strains and is related to the alloy formation. The annealing experiments show all the catalysts present an exceptional thermal stability when annealed in inert ambient, especially that of the Pt1Ru1/C catalyst. Besides, it is interesting to note that there is no thermal expansion evidence from the patterns.

关键词： In situ X-ray diffraction PtRu/C nanocatalyst Thermal stability

Electrical and thermoelectric study of two-dimensional crystal of NbSe2

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Chinese Physics B 2020年第8期29卷 137-142页

作者： Xin-Qi li zhi-lin li Jia-Ji Zhao Xiao-Song Wu State Key Laboratory for Artificial Microstructure and Mesoscopic Physics Beijing Key Laboratory of Quantum DevicesPeking UniversityBeijing 100871China Frontiers Science Center for Nano-optoelectronics and Collaborative Innovation Center of Quantum Matter Beijing 100871China

We report experimental investigation of the resistivity and Nernst effect in two-dimensional(2D)NbSe2 crystals.A strongly enhanced Nernst effect,100 times larger than that in bulk NbSe2,caused by moving vortices is observed in thin *** is found that in the low temperature,high magnetic field regime,pinning effects show little dependence on the thickness and resistivity of the superconductor *** Nernst signals persist above the superconducting transition,suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations.A magnetic field induced superconductor-insulator transition(SIT)is evident,which is surprising in that such a SIT usually takes place in disordered dirty superconductors,while our samples are highly crystalline and close to the clean ***,our results expand the scope of SIT into 2D crystal clean superconductors.

关键词： two-dimensional superconductivity Nernst effect superconducting fluctuations superconductor-insulator transition

SAR Image Coregistration Using Fringe Definition Detection

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Journal of Mountain Science 2013年第5期10卷 790-800页

作者： YANG Ying-hui CHEN Qiang liU Guo-xiang li zhi-lin CHENG Hai-qin liu li-yao Department of Remote Sensing and Geoinformation Engineering Southwest Jiaotong University School of Civil Engineering and Architecture East China Jiaotong University

In order to overcome the limitation of cross correlation coregistration method for Synthetic Aperture Radar （SAR） interferometric pairs with low coherence, a new image coregistration algorithm based on Fringe Definition Detection （FDD） is presented in this paper. The Fourier transformation was utilized to obtain spectrum characteristics of interferometric fringes. The ratio between spectrum mean and peak was proposed as the evaluation index for identifying homologous pixels from interferometric images. The satellites ERS-1/2 C-band SAR acquisitions covering the Yangtze River plain delta, eastern China and ALOS/PALSAR L-band images over the Longmen Shan mountainous area, southwestern China were respectively employed in the experiment to validate the proposed coregistration method. The testing results suggested that the derived Digital Elevation Model （DEM） from FDD method had good agreement with that from the cross correlation method as well as the reference DEM at high coherence area. However, The FDD method achieved a totally improved topographic mapping accuracy by 24 percent in comparison to the cross correlation method. The FDD method also showed better robustness and achieved relatively higher performance for SAR image eoregistration in mountainous areas with low coherence.

关键词： SAR image coregistration Spectrumcharacteristics Fringe definition detection Interferometric Synthetic Aperture Radar (InSAR) Accuracy assessment