检索结果-南通市图书馆

Journal of magnesium and Alloys 2020年第2期8卷 523-536页

作者： Lingyun An Ying ma le Sun Zhanying Wang Sheng Wang State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Plasma electrolytic oxidation(PEO)coatings were prepared on AZ91D magnesium alloys in alkaline silicate-based electrolyte with and without *** mutual effects among additives including TiC particles,dispersant polyethylene glycol 6000(PEG6000)and anionic surfactant sodium dodecyl sulfate(SDS)were studied based on orthogonal *** content and distribution of TiC deposited in the coatings were measured by EPma and *** thicknesses,phase compositions,microstructures and corrosion resistances of the codlings were cAarnined by using TT260 eddy current tuickncss gage,XRD,SEM and clcctrochcniical test,*** results show that the experiment design of this study is the key to study the mutual effects among these *** additive and their interactions all remarkably influence TiC content and corrosion resistance of the *** size TiC is much easier to migrate towards the anode,and the interaction between PEG6000 and SDS both effectively prevents its agglomeration and increases the number of its negative surface charges,which further increase the migration rate and the deposited uniformity of TiC and make TiC have more opportunity to deposit in the discharge ***,when smaller size TiC,PEG6000 and SDS are all added into the electrolyte,they could improve the anti-corrosion property of the coating to the largest extent attributed to higher TiC content and the densest microstructure of the coating.

关键词： magnesium alloys Plasma electrolytic oxidation Additives Mutual effects Orthogonal experiment Corrosion resistance

Microstructures and grain refinement performance of Al-Ti-B-C grain refiner via powder metallurgy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2022年第7期41卷 2357-2362页

作者： Cong Xu wen-Long Xiao Shi-Zhen wen Yue-Jun Zhen Chao-Li ma Key Laboratory of Aerospace Advanced materials and Performance of Ministry of Education School of Material Science and EngineeringBeihang UniversityBeijing 100191China Lizhong Group Baoding Lizhong Wheel Manufacturing Co.Ltd.Baoding 071000China

The Al-5Ti-0.5B-0.5C grain refiner was pre-pared by powder metallurgy(PM).Microstructures of the grain refiner and its grain refinement performance in commercially pure aluminum(Al)were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),and differential scanning calorimetry(DSC).It is found that the average grain size of commercially pure Al can be reduced from~15,000 to~180μm by the addition of Al-5Ti-0.5B-0.5C grain refiner prepared by PM,based on 0.01 wt%Ti *** grain refinement efficiency begins to decrease slightly when the grain refiner is kept in the melt for 60 *** grain refinement is attributed to high stability,proper size,and high density of Al3Ti,TiB2,and TiC particles.

关键词： Al–Ti–B–C Powder metallurgy Microstructure Grain refinement

Continuous Homogeneous Selections of Set-Valued Metric Generalized Inverses of Linear Operators in Banach Spaces

在线全文

学校读者我要写书评

暂无评论

Acta mathematica Sinica,English Series 2012年第1期28卷 45-56页

作者： Hai Feng ma Henryk HUDZIK wen WANG School of mathematical Science Harbin Normal UniversityHarbin 150025P.R.China Faculty of mathematics and Computer Science Adam Mickiewicz UniversityUmultowska 8761-614 PoznanPoland Yuan-Yung Tseng Functional Analysis Research Center Harbin Normal UniversityHarbin 150025P.R.China

In this paper, continuous homogeneous selections for the set-valued metric generalized inverses T^ of linear operators T in Banach spaces are investigated by means of the methods of geometry of Banach spaces. Necessary and sufficient conditions for bounded linear operators T to have continuous homogeneous selections for the set-valued metric generalized inverses T~ are given. The results are an answer to the problem posed by Nashed and Votruba.

关键词： Continuous homogeneous selection metric generalized inverse approximative compactness metric projection

Recent Progress on Transition Metal （Fe, Co, Ni, Ti and V） Complex Catalysts in Olefin Polymerization with High Thermal Stability

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2017年第5期35卷 531-540页

作者： Zhifeng ma wenhong Yang wen-Hua Sun Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial *** review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of *** the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also *** plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.

关键词： thermal stability transition metal complex olefin polymerization homogenous catalysis ligand effects

Online scheduling of jobs with kind release times and deadlines on a single machine

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied mathematics(A Journal of Chinese Universities) 2019年第1期34卷 113-126页

作者： LI wen-jie ma Ran FENG Qi School of mathematical Sciences Luoyang Normal University School of mathematics and Statistics Qingdao University Department of Information and Computation Science Zhongyuan University of Technology

This paper studies online scheduling of jobs with kind release times on a single machine. Here "kind release time" means that in online setting, no jobs can be released when the machine is busy. Each job J has a kind release time r(J) ≥ 0, a processing time p(J) > 0 and a deadline d(J) > 0. The goal is to determine a schedule which maximizes total processing time( p(J)E(J)) or total number( E(J)) of the accepted jobs. For the first objective function p(J)E(J), we first present a lower bound 2(1/2), and then provide an online algorithm leJ with a competitive ratio of 3. This is the first deterministic algorithm for the problem with a constant competitive ratio. When p(J) ∈ {1, k}, k > 1 is a real number, we first present a lower bound min{(1 + k)/k, 2 k/(1 + k)}, and then we show that leJ has a competitive ratio of1 + k/k. In particular, when all the k length jobs have tight deadlines, we first present a lower bound max{4/(2 + k), 1}(for p(J)E(J)) and 4/3(for E(J)). Then we prove that leJ is k/k-competitive for p(J)E(J) and we provide an online algorithm H with a competitive ratio of 2 k/( k + 1) for the second objective function E(J).

关键词： scheduling online algorithm kind release time deadline

Modeling and analysis of Internet worm propagation

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 63-68页

作者： SU Fei LIN Zhao-wen ma Yan Institute of Networking Technology Beijing University of Posts and Telecommunications Beijing 100876 China Beijing Key Laboratory of Intelligent Telecommtmications Software and Multimedia Beijing University of Posts and Telecommunications Beijing 100876 China

Although the frequency of Internet worm＇s outbreak is decreased during the past ten years, the impact of worm on people＇s privacy security and enterprise＇s efficiency is still a severe problem, especially the emergence of botnet. It is urgent to do more research about worm＇s propagation model and security defense. The well-known worm models, such as simple epidemic model （SEM） and two-factor model （TFM）, take all the computers on the internet as the same, which is not accurate because of the existence of network address translation （NAT）. In this paper, we first analyze the worm＇s functional structure, and then we propose a three layer worm model named three layres worm model （TLWM）, which is an extension of SEM and TFM under NAT environment. We model the TLWM by using deterministic method as it is used in the TFM. The simulation results show that the number of NAT used on the Internet has effects on worm propagation, and the more the NAT used, the slower the worm spreads. So, the extensive use of NAT on the Internet can restrain the worm spread to some extent.

关键词： worm propagation model TLWM NAT

Microstructure and tensile properties of Ti-62421S alloy plate with different annealing treatments

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2018年第7期37卷 568-573页

作者： Yong-Ling Wang Xiao-Yun Song wen ma wen-Jing Zhang wen-Jun Ye Song-Xiao Hui State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals Division of Science and Technology Information General Research Institute for Nonferrous Metals

Ti-62421S （Ti-6A1-2Sn-4Zr-2Nb-lMo-0.2Si） is a novel short-time using high-temperature titanium alloy. The effects of annealing on microstructure and tensile properties of Ti-62421S alloy plate were studied through optical microscopy （OM）, electron probe microanalysis （EPma）, transmission electron microscopy （TEM）, and tensile tests. The results show that, with annealing tem- perature increasing, the volume fraction of primary α（αp）- phase decreases while that of transformed β（βt）-structure and secondary α （αs）-phase increases. The room-temperature strength and plasticity are insensitive to annealing temperature. However, with annealing temperature increasing, the tensile strength decreases at 550℃, while increases at 600 and 650℃ instead. It is suggested that, at 550℃, the strengthening mechanism is mainly boundary strengthening and the biggest contributor is ap-phase by providing αp/β-boundary area. Above 600 ℃, the strengthening mechanism is grain strengthening, where αs-phase strengthens the β-phase.

关键词： High temperature titanium alloy Ti-62421S Heat treatment Microstructure Tensile properties

Dynamical rational solutions and their interaction phenomena for an extended nonlinear equation

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第3期75卷 1-11页

作者： Karmina K Ali Abdullahi Yusuf wen-Xiu ma Department of mathematics University of ZakhoZakhoIraq Department of Computer Engineering Biruni UniversityIstanbulTurkey Department of Computer Science and mathematics LebaneseAmerican UniversityBeirutLebanon Department of mathematics and Statistics University of South FloridaTampaFL 33620United States of America Department of mathematics Zhejiang Normal UniversityJinhua 321004China Department of mathematics King Abdulaziz UniversityJeddah 21589Saudi Arabia School of mathematical and Statistical Sciences North-West UniversityMafikeng CampusMmabatho 2735South Africa

In this paper,we analyze the extended Bogoyavlenskii-Kadomtsev-Petviashvili(eBKP)equation utilizing the condensed Hirota's *** accordance with a logarithmic derivative transform,we produce solutions for single,double,and triple M-lump ***,we investigate the interaction solutions of a single M-lump with a single soliton,a single M-lump with a double soliton,and a double M-lump with a single ***,we create sophisticated single,double,and triple complex soliton wave *** extended Bogoyavlenskii-Kadomtsev-Petviashvili equation describes nonlinear wave phenomena in fluid mechanics,plasma,and shallow water *** selecting appropriate values for the related free parameters we also create three-dimensional surfaces and associated counter plots to simulate the dynamical characteristics of the solutions offered.

关键词： simplified Hirota's method lump solution mixed solution complex multiple soliton eBKP equation

Hardware system design for UHF surface velocities radar

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第2期18卷 255-258页

作者： wen Biyang ma Zhigang Yuan Fei Zhou Hao School of Electronic Information Wuhan Univ. Wuhan 430079 P. R. China Southwest China Research Inst. of Electronic Equipment Chengdu 610036 P. R. China

UHF surface velocities radar is developed based on the successful ocean state measuring and analyzing radar system. The design method for UHF radar system is presented. It is designed to operate at UHF channel, and the transmit power is under 5W. maximum range of field test over fresh water can be a kilometer. The field tests at Tangsun River and at majiatan and Gaobazhou proved that USVR System can be used successfully.

关键词： UHF Surface velocities radar Bragg resonant.

Perturbations of Moore–Penrose Metric Generalized Inverses of Linear Operators in Banach Spaces

在线全文

学校读者我要写书评

暂无评论

Acta mathematica Sinica,English Series 2014年第7期30卷 1109-1124页

作者： Hai Feng ma Shuang SUN Yu wen WANG wen Jing ZHENG School of mathematical Science Harbin Normal University Department of mathematics Hulunbuir College

In this paper, the perturbations of the Moore-Penrose metric generalized inverses of linear operators in Banach spaces are described. The Moore Penrose metric generalized inverse is homo- geneous and nonlinear in general, and the proofs of our results are different from linear generalized inverses. By using the quasi-additivity of Moore-Penrose metric generalized inverse and the theorem of generalized orthogonal decomposition, we show some error estimates of perturbations for the single- valued Moore-Penrose metric generalized inverses of bounded linear operators. Furthermore, by means of the continuity of the metric projection operator and the quasi-additivity of Moore-Penrose metric generalized inverse, an expression for Moore-Penrose metric generalized inverse is given.

关键词： Banach space Moore-Penrose metric generalized inverse perturbation