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Improved Algorithm for Solving Discrete Logarithm Problem by Expanding Factor

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China Communications 2020年第4期17卷 31-41页

作者： Bin Qi Jie ma kewei Lv State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of SciencesBeijing 100093China Data Assurance Communication Security Research Center Chinese Academy of SciencesBeijing 100093China School of Cyber Security University of Chinese Academy of SciencesBeijing 100093China

The discrete logarithm problem(DLP)is to find a solution n such that g^n=h in a finite cyclic group G=,where h∈G.The DLP is the security foundation of many cryptosystems,such as RSA.We propose a method to improve Pollard’s kangaroo algorithm,which is the classic algorithm for solving the DLP.In the proposed algorithm,the large integer multiplications are reduced by controlling whether to perform large integer multiplication.To control the process,the tools of expanding factor and jumping distance are introduced.The expanding factor is an indicator used to measure the probability of collision.Large integer multiplication is performed if the value of the expanding factor is greater than the given bound.The improved algorithm requires an average of(1.633+o(1))q(1/2)times of the large integer multiplications.In experiments,the average large integer multiplication times is approximately(1.5+o(1))q(1/2).

关键词： discrete logarithm algorithm pollard’s kangaroo algorithm jumping distance

NUMERICAL SIMULATION FOR MEASURING YIELD STRENGTH OF THIN METAL FILM BY NANOINDENTATION METHOD

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中国有色金属学会会刊：英文版 1997年第3期7卷 66-69页

作者： ma, Dejun Xu, kewei He, Jiawen Xi'an Jiaotong Univ Xi'an China

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关键词： nanoindentation method thin metal film mechanical properties finite element method

Structural and electronic properties of atomic oxygen adsorption on Cu(111) surface:A first-principles investigation

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Science China(Physics,Mechanics & Astronomy) 2013年第3期56卷 573-580页

作者： ma LiangCai ZHANG JianMin XU kewei College of Physics and Information Technology Shaanxi Normal University School of Physics and Electrical Information Engineering Ningxia University State Key Laboratory for Mechanical Behavior of materials Xi'an Jiaotong University

By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found that the fcc-hollow site is the most stable site for oxygen adsorption.The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms.Except for coverage of 1.00 ML,the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers,and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML,respectively.With an increasing oxygen coverage,the work function increases and the surface dipole moment decreases.Electron transfer from the first layer Cu atoms to O adatoms indicates the O-Cu bond having some degree of ionic character,while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character.Moreover,with the increasing oxygen coverage,more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system,but increase in the PDOS at the Fermi level.This implies an enhancement in the metallic character of the O/Cu(111) system.

关键词： adsorption oxygen relaxation electronic structures first-principles calculation

First-principles study of the adsorption of oxygen atoms on copper nanowires

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Science China(Physics,Mechanics & Astronomy) 2012年第3期55卷 413-418页

作者： ma LiangCai ZHANG JianMin XU kewei College of Physics and Information Technology Shaanxi Normal UniversityXi’an 710062China School of Physics and Electrical Information Engineering Ningxia UniversityYinchuan 750021China Department of Physics Xi’an University of Arts and ScienceXi’an 710065China

By using first-principles calculations,we have systematically investigated the structural stability and electronic properties of a single oxygen atom adsorbed on the surface of foursquare Cu nanowires for a wide range of adsorption sites.In view of binding energy maximization,we found that the long bridge site at the edge of the Cu nanowires is the most stable site for oxygen adsorption,which is always slightly energetically favorable compared with the hollow site at the surface.The electron transferring from Cu atoms to O adatom and a significant polarization indicate the O-Cu chemical bond,showing some degree of ionic character.In addition,the hybridization between O-2p and Cu-3d states implies the O-Cu bond which also shows some degree of covalence character.The main factors which affect the oxygen preferred adsorption site are analyzed from the local geometrical configurations and electronic properties.

关键词：第一原理计算原子吸附铜原子纳米线氧原子结构稳定性电子性质吸附原子

重复经颅磁刺激对首发抑郁症患者执行功能的影响研究

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联勤军事医学 2024年第3期38卷 222-227页

作者：马竹静孙科伟关慕桢汪国强陈晨张良谷亚男杨群空军军医大学军事医学心理学系陕西西安710032 空军军医大学基础医学院陕西西安710032 西安医学院精神卫生学教研室

目的通过采集行为学和脑电数据,考察重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)对首发抑郁症患者的疗效及对执行功能的影响,初步探讨rTMS治疗抑郁症患者潜在的认知神经影响的机制。方法采用随机数字表法将首... 详细信息

目的通过采集行为学和脑电数据,考察重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)对首发抑郁症患者的疗效及对执行功能的影响,初步探讨rTMS治疗抑郁症患者潜在的认知神经影响的机制。方法采用随机数字表法将首发抑郁症患者分为试验组(n=26)和对照组(n=25),试验组患者进行8周的rTMS联合药物治疗,对照组患者仅进行单纯药物治疗。于干预前和干预后采用汉密尔顿抑郁量表24(24-item Hamilton depression rating scale,HAMD-24)、汉密尔顿焦虑量表14(14-item Hamilton anxiety rating scale,HAma-14)以及行为学工具和事件相关电位(event-related potential,ERP)评估患者的抑郁焦虑状态和执行功能的变化。结果两组抑郁症患者治疗后的HAMD-24评分和HAma-14评分较干预前均显著下降(P均<0.001),且试验组患者HAMD-24评分显著低于对照组(P<0.05)。Go/Nogo任务中,两组抑郁症患者Nogo条件正确应答数较干预前均明显提升(P均<0.05);Stroop任务中,试验组抑郁症患者不一致条件的正确应答数较干预前明显提升,不一致条件反应时较干预前明显变短,且试验组抑郁症患者不一致条件的正确应答数较对照组明显提升、不一致条件反应时明显变短(P均<0.05)。脑电指标中,试验组抑郁症患者干预后较干预前诱发了更大的Nogo N2波幅和P3波幅(P均<0.05);试验组抑郁症患者的N2差异波波幅和P3差异波波幅显著大于对照组(P均<0.05)。结论rTMS可以加强抑郁症患者的认知神经活动水平,提升执行功能,对抑郁症患者抑郁症状的治疗效果更好。

关键词：抑郁症重复经颅磁刺激药物治疗执行功能

Tailoring d-band center over electron traversing effect of Ni M@C-CoP(M=Zn,Mo,Ni,Co)for high-performance electrocatalysis hydrogen evolution

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Journal of materials Science & Technology 2023年第35期166卷 164-172页

作者： Hao Luo Xudong Zhang Hui Zhu Kexin Zhang Fan Yang kewei Xu Sen Yu Dagang Guo State Key Laboratory for Mechanical Behavior of materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an710049China Center for High Performance Computing Network Information CenterXi’an Jiaotong UniversityXi’an710049China State Key Laboratory for manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an710049China Shaanxi Key Laboratory of Biomedical Metal materials Northwest Institute for Non-ferrous Metal ResearchXi’an710016China

Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like electronic structures are a potential candidate for the HER,but those are prone to be strongly bound with hydrogen intermediates(H∗),resulting in sluggish HER kinetics.Herein we report a unique hybrid structure of CoP anchored on graphene nanoscrolls@carbon nano tubes(CNTs)scaffold(Ni M@C-CoP)encapsulating various Ni M(M=Zn,Mo,Ni,Co)bimetal nanoalloy via chemical vapor deposi-tion(CVD)growth of CNT on graphene nanoscrolls followed by the impregnation of cobalt precursors and phosphorization for efficiently electrocatalytic hydrogen evolution.CoP nanoparticles mainly scattered at the tip of CNT branches which exhibited the analogical“Three-layer core-shell”structures.Experiments and density functional theory(DFT)calculations consistently disclose that the encapsulated various NiMs can offer different numbers of electrons to weaken the interactions of outmost CoP with H∗and push the downshift of the d-band center to different degrees as well as stabilize the outmost CoP nanopar-ticles to gain catalytic stability via the electron traversing effect.The electrocatalytic HER activity can be maximumly enhanced with low overpotentials of 78 mV(alkaline)and 89 mV(acidic)at a current density of 10 ma/cm^(2) and sustained at least 24 h especially for NiZn@C-CoP catalyst.This novel system is distinct from conventional three-layer heterostructure,providing a specially thought of d-band center control engineering strategy for the design of heterogeneous catalysts and expanding to other electrocat-alysts,energy storage,sensing,and other applications.

关键词： Electron traversing effect 3D graphene/CNT CoP nanoparticle d-band center Hydrogen evolution

Robust Semi-nonnegative matrix Factorization with Adaptive Graph Regularization for Gene Representation

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Chinese Journal of Electronics 2020年第1期29卷 122-131页

作者： JIANG Wei ma Tingting FENG Xiaoting ZHAI Yun TANG kewei ZHANG Jie School of mathematics Liaoning Normal University E-Government Research Center Chinese Academy of Governance

Various data representation algorithms have been proposed for gene expression. There are some shortcomings in traditional gene expression methods,such as learning the ideal affinity matrix to effectively capture the geometric structure of genetic data space,and reducing noises and outliers influences of data input.We propose a novel matrix factorization algorithm called Robust semi-nonnegative matrix factorization(RSNMF)with adaptive graph regularization, which simultaneously performs matrix robust factorization with learning affinity matrix in a unified optimization framework. RSNMF also uses a loss function based on ?2,1-norm to improve the robustness of the model against noises and outliers.A novel Augmented Lagrange multiplier(ALM) is designed to obtain the optimal solution of RSNMF. The results of extensive experiments that were performed on gene expression datasets demonstrate that RSNMF outperforms the other algorithms, which validates the effectiveness and robustness of RSNMF.

关键词： Adaptive graph matrix factorization Robustness

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自然资源综合化“一查”体系构建技术研究

地理空间信息 2024年第4期22卷 76-79页

作者：马克委王胜利朱益虎罗方权王云凯闫昶李安民江苏省地质测绘院江苏南京211102

长期以来,受自然资源调查监测实施部门分散的影响,自然资源调查业务中概念不统一、内容有交叉、指标相矛盾等问题比较突出,尚未形成统一的技术标准和方法,且成果难以共享。针对江苏省自然资源调查监测工作推进和业务管理的实际需求,以... 详细信息

长期以来,受自然资源调查监测实施部门分散的影响,自然资源调查业务中概念不统一、内容有交叉、指标相矛盾等问题比较突出,尚未形成统一的技术标准和方法,且成果难以共享。针对江苏省自然资源调查监测工作推进和业务管理的实际需求,以自然资源综合调查监测国家试点项目为依托,按照“一查”试点的工作任务与要求,开展了调查标准体系构建与技术方法研究。完成了表达资源禀赋与利用的自然资源分类标准、指标体系和数据库标准的制定,提出了“一底两分多码”的自然资源多级实体定界与多重属性表达方法,构建了服务“多用”的“一查”技术体系,能够为自然资源调查和“两统一”管理、国土空间规划编制等业务提供支撑和依据。

关键词：自然资源调查监测体系构建多级实体定界多重属性表达实践方法优化

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Effects of annealing temperature on the microstructure and hardness of TiAlSiN hard coatings

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Chinese Science Bulletin 2011年第16期56卷 1727-1731页

作者： WANG Xin XU JianHua ma ShengLi XU kewei State Key Laboratory for Mechanical Behavior of materials Xi' an Jiaotong University Xi' an 710049 China

TiAlSiN hard coatings were synthesized on high-speed steel using an arc ion enhanced magnetic sputtering hybrid system.The microstructure and hardness of the coatings at different annealing temperatures were explored by means of XRD,TEM,EDAX and Vickers indentation.The as-deposited TiAlSiN coatings were confirmed to be amorphous due to high depositing rate and low deposition temperature during the film growth.The transformation from amorphous to nanocomposites of nano-crystallites and amorphousness were observed after the annealing treatment,the microstructure of TiAlSiN coatings annealed at 800°C and 1000°C were consisted of crystalline hcp-AlN,fcc-TiN and amorphous phase,however,the coatings were only consisted of fcc-TiN and amorphous phase when annealing at 1100°C and 1200°C.Meanwhile,the formation of Al2O3 was detected on the coating surface after annealing at 1200°C and it indicated the excellent oxidation resistance of the TiAlSiN coatings under the present experimental conditions.Furthermore,the average grain size of the TiAlSiN coatings after high temperature annealing even at 1200°C was less than 30 nm and the size increased with the increasing temperature.However,the hardness of the so-deposited coatings with HV0.2N=3300 dramatically decreased with the increase of temperature and reached nearly to the hardness of TiN coatings with HV0.2N=2300.

关键词：退火温度硬质涂层微观结构硬度 TiN涂层混合动力系统沉积温度纳米复合材料