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A FEASIBLE DIRECTION ALGORITHM WITHOUT LINE SEARCH FOR SOLVING MAX-BISECTION PROBLEMS

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Journal of Computational Mathematics 2005年第6期23卷 619-634页

作者： feng-min xu cheng-xian xu Hong-gang xue Department of Mathematics of Faculty of Science Xi'an Jiaotong University Xi'an 710049 China

This paper concerns the solution of the NP-hard max-bisection problems. NCP functions are employed to convert max-bisection problems into continuous nonlinear programming problems. Solving the resulting continuous nonlinear programming problem generates a solution that gives an upper bound on the optimal value of the max-bisection problem. From the solution, the greedy strategy is used to generate a satisfactory approximate solution of the max-bisection problem. A feasible direction method without line searches is proposed to solve the resulting continuous nonlinear programming, and the convergence of the algorithm to KKT point of the resulting problem is proved. Numerical experiments and comparisons on well-known test problems, and on randomly generated test problems show that the proposed method is robust, and very efficient.

关键词： Max-Bisection problem Feasible direction algorithm NCP function Convergence

质子入射In靶激发L系特征X射线的角分布研究

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原子与分子物理学报 2025年第2期42卷 98-104页

作者：柳钰王兴徐忠锋周贤明程锐张小安梁昌慧咸阳师范学院与中国科学院近代物理研究所联合共建离子束与光物理实验室咸阳712000 西安交通大学物理学院西安710049 中国科学院近代物理研究所兰州730000

本论文实验测量并分析了发射角以10°为间隔,125°-155°范围内,入射能量为250 keV的质子束激发In靶产生的特征L系X射线谱,根据实验测得能谱结果,综合考虑探测器的探测效率后,计算了不同探测角度下特征X射线的相对强度比L_(ι)/L_(γ1)... 详细信息

本论文实验测量并分析了发射角以10°为间隔,125°-155°范围内,入射能量为250 keV的质子束激发In靶产生的特征L系X射线谱,根据实验测得能谱结果,综合考虑探测器的探测效率后,计算了不同探测角度下特征X射线的相对强度比L_(ι)/L_(γ1);由相对强度比L_(ι)/L_(γ1)与二阶勒让德函数P_(2)(cosθ)之间的函数关系,发现特征X射线Lι在被测能量下呈各向异性发射,推得Lι特征X射线的各向异性参数β为-0.179±0.011,进而得到In靶L_(3)亚壳层的定向度A_(20)为-0.422±0.025,实验结果与理论预测一致.根据PWBA(Plane wave born approximation)模型和ECPSSR(Energy-loss coulomb-repulsion perturbed-stationary-state relativistic)模型,计算了250 keV质子入射下,In靶L亚壳层电离截面σ及Coster-Kronig跃迁矫正因子κ,在根据各向异性参数计算L_(3)亚壳层定向度的过程中考虑了Coster-Kronig跃迁的作用.分析认为本实验碰撞速度下,通过电子转移方式产生空穴的截面比直接电离小的多,所以没有对L_(3)亚壳层定向度进行电子转移因素的修正.

关键词：碰撞电离特征X射线角分布各向异性

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Resonant tunneling in disordered borophene nanoribbons with line defects

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npj Computational Materials 2022年第1期8卷 1230-1237页

作者： Pei-Jia Hu Si-xian Wang xiao-feng Chen Zeng-Ren liang Tie-feng Fang Ai-min Guo Hui xu Qing-feng Sun Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha410083China School of Physical Science and Technology Lanzhou UniversityLanzhou730000China School of Sciences Nantong UniversityNantong226019China International Center for Quantum Materials School of PhysicsPeking UniversityBeijing100871China Collaborative Innovation Center of Quantum Matter Beijing100871China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing100190China

Recently,borophene has attracted extensive interest as the wonder material,showing that line defects(LDs)occur widely at the interface between V_(1/5)and V_(1/6)boron ***,we study theoretically the electron transport through two-terminal disordered borophene nanoribbons(BNRs)with random distribution of *** results indicate that LDs strongly affect the electron transport properties of *** V_(1/5)and V_(1/6)BNRs exhibit metallic behavior without any LD,in agreement with *** in the presence of LDs,the overall electron transport ability is dramatically decreased,but some resonant peaks of conductance quantum are found in the transmission spectrum of any disordered BNR with arbitrary arrangement of *** disordered BNRs exhibit metal-insulator transition with tunable transmission gap in the insulating ***,two evolution phenomena of resonant peaks are revealed for disordered BNRs with different *** results may help for understanding structure-property relationships and designing LD-based nanodevices.

关键词： tunneling boron resonant

Quantitative relationship between visibility and mass concentration of PM2.5 in Beijing

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Journal of Environmental Sciences 2006年第3期18卷 475-481页

作者： WANG Jing-li ZHANG Yuan-hang SHAO min LIU xu-lin ZENG Li-min cheng Cong-lan xu xiao-feng Institute of Urban Meteorology China Meteorological Administration Beijing 100089 China State Joint Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing 100871 China Beijing Meteorological Information and Network Center Beijing 100089 China

The pollution of particulate matter less than 2.5μm （PM2.5） is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U,S, national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles （PM2.5） cause atmospheric visibility deterioration through light extinction, The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different： power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5.

关键词： PM2.5 atmospheric urban aerosol air pollution meteorological factor visibility

A Continuation Algorithm for Max-Cut Problem

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Acta Mathematica Sinica,English Series 2007年第7期23卷 1257-1264页

作者： feng min xu cheng xian xu Xing Si LI School of Science Xi'an Jiaotong University State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology

A continuation algorithm for the solution of max-cut problems is proposed in this paper. Unlike the available semi-definite relaxation, a max-cut problem is converted into a continuous nonlinear programming by employing NCP functions, and the resulting nonlinear programming problem is then solved by using the augmented Lagrange penalty function method. The convergence property of the proposed algorithm is studied. Numerical experiments and comparisons with the Geomeans and Williamson randomized algorithm made on some max-cut test problems show that the algorithm generates satisfactory solutions for all the test problems with much less computation costs.

关键词： max-cut problem NCP function convex function augmented Lagrange penalty function method

Synthesis, Structure, and Magnetic Properties of One Polyoxometalate (W/Mo) Compound: H_8K{[Ni(H_2O)_5]_2(H_2Mo_(1.80)W_(10.20)O_(42))}Cl_3·16H_2O

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Chinese Journal of Structural Chemistry 2007年第5期26卷 599-605页

作者： LIU Ying DOU Jian-min WANG Da-Qi ZHANG xian-Xi LI Da-cheng xu feng ZHOU Lei College of Chemistry and Chemical Engineering Liaocheng University Liaocheng 252059 China

One new polyoxometalate compound connected via nickel/potassium cations, H8K{[Ni（H2O）5]2（H2Mo1.80W10.20O42）}Cl3·16H2O 1, was prepared and characterized by elemental analysis and IR spectroscopy. Single-crystal X-ray diffraction analysis results reveal that clusters of [Ni（H2O）5]2（H2Mo1.80W10.20O42）}^6-in compound 1 are linked by potassium cations to form one- dimiensional chains, based on which a three-dimensional network is further constructed via the hydrogen bonds of O…O and O…Cl. Magnetic measurements show that compound 1 has paramagnetic properties. Crystal data： H62Cl3KMo1.80Ni2O68W10.20, Mr = 3461.33, monoclinic, space group C2/c, a = 18.9291（19）, b = 16.6758（17）, c = 19.1064（19）A, β = 106.6880（10）°, V = 5777.1（10）A^3, Z = 4, Dc = 3.980 g/cm^3, F（000） = 6250, μ = 21.574 mm^-1, R = 0.0579 and wR = 0.1623 （Ⅰ 〉 2σ（Ⅰ））.

关键词： polyoxomolybdate molybdate nickel sodium X-ray analysis magnetic

Robot-assisted retroperitoneal laparoscopic excision of perirenal vascular tumor: A case report

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World Journal of Clinical Cases 2020年第10期8卷 2050-2055页

作者： cheng Zhang Bin Fu Song xu xiao-Chen Zhou xiao-feng cheng Wen-Qing Fu Gong-xian Wang Department of Urology The First Affiliated Hospital of Nanchang UniversityNanchang 330000JiangXi ProvinceChina

BACKGROUND A vascular tumor is a benign tumor with unique clinical and pathological *** vascular tumor is extremely rare and has not yet been ***,it manifests as soreness and *** ultrasound and renal angiography illustrated the perirenal mass,which was closely connected with the kidney and the surrounding tissues and *** showed extensive embedded perirenal fat,and thin-walled vascular tissue displayed a pink stain due to red blood *** SUMMARY Herein,a case of robot-assisted retroperitoneal laparoscopic excision of a perirenal vascular tumor is *** of the clinical,biological,and histological features of the perirenal vascular tumor can provide an in-depth understanding of the disease,which provides a theoretical and practical basis for better diagnosis and *** This study contributes to a practical basis for the diagnosis and treatment of perirenal hemangiom.

关键词： Kidney Vascular tumor Treatment Robot-assisted surgery

Complex genesis of multiperiod fractures in the Middle Triassic Leikoupo Formation in the Pengzhou gas field, western Sichuan Basin, China

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Petroleum Science 2023年第1期20卷 161-176页

作者： xiao-Fei Hu Hu-cheng Deng Jian-Hua He Zhong-min Shen xian-feng Peng College of Energy Chengdu University of TechnologyChengduSichuan 610059China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(chengdu University of Technology) ChengduSichuan 610059China

The cumulative expression of multistage deformation is complex multiperiod fractures,which are commonly seen in tectonic *** Middle Triassic Leikoupo Formation in the western Sichuan Basin Depression,China,is a typical marine carbonate reservoir with natural fractures caused mainly by tectonic *** to outcrops,drill cores,image logging,and fluid inclusions,the fracture characteristics,types of natural fractures,and interactions of fractures are *** total,419 natural fractures in 493.2 m of cores from 7 wells are investigated,which are mainly shear and tensile fractures with a small number of weathering generated ***,the results of the stable isotope analysis of δ13C and δ18O,as well as the flow fluid inclusion data,reveal four tectonic periods of fractures with different *** on the history of regional tectonic evolution,indicating one period of weathering fractures ascribable to stratal uplift and three periods of structural fractures related to the sequential tectonic movements of the Longmenshan fault *** analyzing the interaction relationships of fractures,three types of fracture interaction relationships are observed:cutting,restraining,and *** four stages fractures are chronologically assigned to(1)the early Indosinian N-S trending compression,(2)the late Indosinian NW-SE compression,(3)the middle Yanshanian NE-SE compression,and(4)the early Himalayan E-W *** influence of natural fractures on gas migration and well production in marine carbonates is discussed,and indicates that tectonic fractures could provide seepage channels for gas migration and accumulation from near or distant hydrocarbon source rocks into the Middle Triassic Leikoupo *** study utilizes a pragmatic approach for understanding the fracture genesis mechanism in oil and gas field with multiperiod fractures.

关键词： Multiperiod fractures Interaction relationships Genesis mechanism Gas migration Leikoupo formation Sichuan basin

Electron emission induced by keV protons from tungsten surface at different temperatures

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Chinese Physics B 2022年第7期31卷 241-246页

作者： Li-Xia Zeng xian-ming Zhou Rui cheng Yu Liu xiao-An Zhang Zhong-feng xu Ion Beam and Optical Physical Laboratory Xianyang Normal UniversityXianyang 712000China Institute of Science and Technology for Laser and Particle Beams Xi’an Jiaotong UniversityXi’an 710049China Institute of Modern Physics Chinese Academy of ScienceLanzhou 730000China

The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50keV–250keV at different *** our experimental results,the total electron emission yield,which contains mainly the kinetic electron emission yield,has a very similar change trend to the electronic stopping *** the same time,it is found that the ratio of total electron emission yield to electronic stopping power becomes smaller as the incident ion energy *** experimental result is explained by the ionization competition mechanism between electrons in different shells of the target *** explanation is verified by the opposite trends to the incident energy between the ionization cross section of M and outer shells.

关键词： electron emission x-ray electronic stopping power work function