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Evaluation of stress intensity factors for bi-material interface cracks using displacement jump methods

Acta Mechanica Sinica 2017年第6期33卷 1051-1064页

作者： k. C. Nehar B. E. Hachi F. Cazes M. Haboussi Laboratoire de développement en mécanique et matériaux (LDMM) Université de Djelfa PB 3117 Djelfa Algeria Laboratoire des Sciences des Procédés et des Matériaux (LSPM) UPR 3407 CNRS Université Paris 13 Paris France

The aim of the present work is to investigate the numerical modeling of interfacial cracks that may appear at the interface between two isotropic elastic materials. The extended finite element method is employed to analyze brittle and bi-material interfacial fatigue crack growth by computing the mixed mode stress intensity factors(SIF). Three different approaches are introduced to compute the SIFs. In the first one, mixed mode SIF is deduced from the computation of the contour integral as per the classical J-integral method,whereas a displacement method is used to evaluate the SIF by using either one or two displacement jumps located along the crack path in the second and third approaches. The displacement jump method is rather classical for mono-materials,but has to our knowledge not been used up to now for a bimaterial. Hence, use of displacement jump for characterizing bi-material cracks constitutes the main contribution of the present study. Several benchmark tests including parametric studies are performed to show the effectiveness of these computational methodologies for SIF considering static and fatigue problems of bi-material structures. It is found that results based on the displacement jump methods are in a very good agreement with those of exact solutions, such as for the J-integral method, but with a larger domain of applicability and a better numerical efficiency(less time consuming and less spurious boundary effect).

关键词： Bi-material interface crack Mixed mode stress intensity factor Displacement jump X-FEM Fatigue crack growth

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Electrochemical study of different membrane materials for the fabrication of stable,reproducible and reusable reference electrode

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Journal of Energy Chemistry 2020年第10期29卷 33-41页

作者： Nawar k.Al-Shara Farooq Sher Sania Z.Iqbal Zaman Sajid George Z.Chen Department of Chemical and Environmental Engineering University of NottinghamUniversity ParkNottingham NG72RDUnited Kingdom School of Mechanical Aerospace and Automotive EngineeringFaculty of EngineeringEnvironmental and ComputingCoventry UniversityCoventry CV12JHUnited Kingdom Department of Biochemistry University of AgricultureFaisalabad 38000Pakistan Department of Process Engineering Memorial University of NewfoundlandSt John’s Newfoundland A1B 3×5Canada

Fabrication of stable,reproducible and reusable reference electrodes for low energy and high-temperature steam splitting is of great interest for hydrogen fuel production without anthropogenic carbon dioxide(CO2)*** study has been conducted for the detection of suitable material for the fabrication of novel reference *** the present scenario,this research is designed to fabricate a novel nickel reference electrode by using operating conditions of eutectic molten hydroxide(NaOH-kOH,49-51 mol%)at temperature 300℃in an ion-conducting membrane of alumina and mullite ***,the designed nickel reference electrode has been examined for its reusability and stability by using electrochemical technique and cyclic *** scans of cyclic voltammetry are performed for both membrane fabricated reference electrode.A slight positive shift in oxidation peaks is observed for mullite membrane electrode(64 mV from scan 1 to 5).The stability measurements are noted by changing the scan rate between 50 and 150 mV s−***,the results show that the Ni/Ni(OH)2 reference electrode covered with a mullite membrane is stable and reusable at 300℃temperature without any *** stability and reusability of prepared nickel reference electrode covered by mullite tube in the eutectic molten hydroxide were up to 9 days to carry out an electrochemical investigation,while for alumina tube reference electrode the stability and reliability were up to 3 *** internal electrolytic material and ionic conductance can play an important role for future studies with this reference electrode along with optimisation of temperature and scan rate parameters.

关键词： Renewable energy Hydrogen production Electrode process Cyclic voltammetry Reference electrode and Molten salts

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Intelligent resource allocation in mobile blockchain for privacy and security transactions: a deep reinforcement learning based approach

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Science China(Information Sciences) 2021年第6期64卷 172-187页

作者： Zhaolong NING Shouming SUN Xiaojie WANG Lei GUO Guoyin WANG Xinbo GAO Ricky Y.k.kWOk School of Communication and Information Engineering Chongqing University of Posts and Telecommunications School of Software Dalian University of Technology State key Laboratory of Industrial Control Technology Zhejiang University Chongqing key Laboratory of Computational Intelligence Chongqing University of Posts and Telecommunications Chongqing key Laboratory of Image Cognition Chongqing University of Posts and Telecommunications Department of Electrical and Electronic Engineering University of Hong Kong

In order to protect the privacy and data security of mobile devices during the transactions in the industrial Internet of Things(IIoT), we propose a mobile edge computing(MEC)-based mobile blockchain framework by considering the limited bandwidth and computing power of small base stations(SBSs). First,we formulate a joint bandwidth and computing resource allocation problem to maximize the long-term utility of all mobile devices, and take into account the mobility of devices as well as the blockchain throughput. We decompose the formulated problem into two subproblems to decrease the dimension of action space. Then,we propose a deep reinforcement learning additional particle swarm optimization(DRPO) algorithm to solve the two subproblems, in which a particle swarm optimization algorithm is leveraged to avoid the unnecessary search of a deep deterministic policy gradient approach. Simulation results demonstrate the effectiveness of our method from various aspects.

关键词： mobile blockchain deep reinforcement learning mobile edge computing power allocation bandwidth allocation

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施工高温作用后CFRP板增强桥梁疲劳损伤及寿命预测（英文）

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中国公路学报 2016年第6期29卷 221-231页

作者：袁鑫 DABNATH S k 郑伟苏州科技大学土木工程学院江苏苏州215011 东南大学土木工程学院江苏南京210096 达卡工程技术大学土木工程学院苏州中固建筑科技有限公司江苏苏州215152

为了探讨碳纤维增强塑料(CFRP)板在沥青摊铺高温环境下加固国外大桥中的疲劳损伤机理及寿命预测,首先介绍Bangabandhu大桥在孟加拉国亚热带湿热环境温度下进行沥青玛蹄脂新桥面铺装的高温加固环境,然后通过钢筋、混凝土和CFRP板应变等... 详细信息

为了探讨碳纤维增强塑料(CFRP)板在沥青摊铺高温环境下加固国外大桥中的疲劳损伤机理及寿命预测,首先介绍Bangabandhu大桥在孟加拉国亚热带湿热环境温度下进行沥青玛蹄脂新桥面铺装的高温加固环境,然后通过钢筋、混凝土和CFRP板应变等参数研究大桥箱梁桥顶板增强梁疲劳裂纹演化、荷载-挠度曲线变化规律及CFRP板应力情况,对梁体抗裂性、刚度和疲劳损伤累积进行分析;最后,根据疲劳裂纹扩展规律和破坏模式,结合试验结果,采用相应的断裂力学分析模型,引入裂纹尖端的应力强度因子计算公式,对试件进行疲劳主裂纹扩展研究。研究结果表明:在沥青摊铺高温作用下,CFRP板仍可以有效抑制混凝土的开裂和裂缝发展,经过CFRP板加固的钢筋混凝土试验梁疲劳寿命有一定提高,经过沥青摊铺高温作用后的CFRP板加固试验梁仍可满足200万次疲劳试验加载。通过da/dN-Δk曲线和裂纹扩展速率进行疲劳寿命预测发现,该方法计算出的理论疲劳寿命与实际的疲劳寿命基本吻合。

关键词：桥梁工程 CFRP板疲劳试验损伤累积寿命预测施工高温桥梁增强

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Suction Performance and Internal Flow of a 2-Bladed Helical Inducer with Inlet Asymmetric Plate

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Journal of Thermal Science 2013年第5期22卷 395-403页

作者： S.Watanabe Y.Uchinono k.Ishizaka A.Furukawa J.-H.kim Department of Mechanical Engineering Kyushu University744 Motooka Nishi-ku Fukuoka 819-0395 Japan Graduate School of Engineering Kyushu University744 Motooka Nishi-ku Fukuoka 819-0395 Japan Oita National College of Technology Hyosung Goodsprings Co. Ltd.Korea

It has been found in our past studies that the installation of asymmetric plate at the inlet of inducer is effective for the suppression of cavitation surge *** the present study,the suction performance of 2-bladed helical inducer with an inlet asymmetric plate is experimentally *** is observed that the suction performance in large flow rate conditions is not significantly influenced by the asymmetric plate,whereas the head of inducer with the asymmetric plate increases just before the head breakdown in partial flow *** understand the mechanism of this additional head,the flow measurements and the numerical simulations are carried *** is found that the circumferential component of absolute velocity at the exit of inducer slightly increases with the development of cavitation in both cases with and without the inlet asymmetric plate,indicating the increase of the theoretical *** theoretical head increase with the inlet asymmetric plate is also confirmed by the unsteady numerical simulations,suggesting that the additional head is achieved through the increase of the theoretical head with the change of the exiting flow from the inducer associated with some amount of cavitation.

关键词： Inducer Cavitation Suction performance Internal flow Inlet asymmetric plate

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Microstructural Evolution of Infrared Brazed CP-Ti Using Ti-Cu-Ni Brazes

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Journal of Materials Science & Technology 2011年第2期27卷 131-138页

作者： C.T.Chang T.Y.Yeh R.k.Shiue C.S.Chang Department of Mechanical Engineering National Hualien Industrial Vocational Senior High SchoolHualien 970TaiwanChina Department of Materials Science and Engineering National Taiwan UniversityTaipei 106TaiwanChina Engineered Materials Solutions 39 Perry AvenueMS 4-1AttleboroMA 02703-2410USA

Microstructural evolution of infrared vacuum brazed CP-Ti using two Ti-based braze alloys,Ti-15Cu-15Ni and Ti-15Cu-25Ni,has been *** infrared brazed joint consisted of eutectic Ti 2 Cu/Ti 2 Ni intermetallic compounds and Ti-rich *** eutectic Ti 2 Cu/Ti 2 Ni intermetallic compounds disappeared from the joint after being annealed at 900 C for 1 *** contrast,the depletion rate of both Cu and Ni from the braze alloy into CP-Ti substrate at 750 C annealing was greatly decreased as compared with that annealed at 900 *** Ti 2 Cu/Ti 2 Ni phases were observed even if the specimen was annealed at 750 C for 15 *** the Ni content of the Ti-15Cu-25Ni braze alloy is much higher than that of the Ti-15Cu-15Ni alloy,the amount of eutectic Ti 2 Cu/Ti 2 Ni phases in Ti-15Cu-25Ni brazed joint is more than that in Ti-15Ci-15Ni brazed ***,similar microstructural evolution can be obtained from the infrared brazed joint annealed at various temperatures and/or time for both filler metals.

关键词： Infrared Brazing CP-Ti Ti-Cu-Ni fillers Microstructure

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N-doped mesoporous alumina for adsorption of carbon dioxide

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Journal of Environmental Sciences 2012年第11期24卷 1979-1984页

作者： Jayshri A.Thote Ravikrishna V.Chatti kartik S.Iyer Vivek kumar Arti N.Valechha Nitin k.Labhsetwar Rajesh B.Biniwale M.k.N.Yenkie Sadhana S.Rayalu Environmental Materials Division National Environmental Engineering Research Institute (NEERI-CSIR)Nagpur 440020India. Lakshminarayan Institute of Technology Nagpur 440001India

N-doped mesoporous alumina has been synthesized using chitosan as the biopolymer template. The adsorbent has been thoroughly investigated for the adsorption of CO2 from a simulated flue gas stream （15% CO2 balanced with N2） and compared with commercially available mesoporous alumina procured from SASOL, Germany. CO2 adsorption was studied under different conditions of pre- treatment and adsorption temperature, inlet CO2 concentration and in the presence of oxygen and moisture. The adsorption capacity was determined to be 29.4 nag CO2/g of adsorbent at 55℃. This value was observed to be 4 times higher in comparison to that of commercial mesoporous alumina at a temperature of 55℃. Basicity of alumina surface coupled with the presence of nitrogen in template in synthesized sample is responsible for this enhanced CO2 adsorption. Adsorption capacity for CO2 was retained in the presence of oxygen; however moisture had a deteriorating effect on the adsorption capacity reducing it to nearly half the value.

关键词： mesoporous alumina chitosan carbon dioxide adsorption flue gas

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Sparse identification-assisted exploration of the atomic-scale deformation mechanism in multiphase CoCrFeNi high-entropy alloys

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Science China(Technological Sciences) 2024年第4期67卷 1124-1132页

作者： XIAO Lu GUO XiaoXiang SUN YuTong WANG Gang LONG WeiMin LIAW Peter k. REN JingLi School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China Institute of Materials Shanghai UniversityShanghai 200444China SkL of Advanced Brazing Metals&Technology Zhengzhou Research Institute of Mechanical EngineeringZhengzhou 450001China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

This study investigated the atomic-scale deformation mechanism of multiphase CoCrFeNi high-entropy alloys(HEAs)at liquid helium,liquid nitrogen,and room temperatures.A million-atom multiphase HEA was prepared using molecular dynamics simulation involving melt and quench *** HEA exhibited high-density dislocations and some twins,consistent with experimental *** analysis revealed an inconsistent evolution of the microstructure under tensile *** particular,the elastic and initial plastic stages exhibited an increase in the disordered structure at the expense of the face-centered cubic and hexagonal close-packed structures,followed by a subsequent transformation involving multiple structural ***,through sparse identification,a model depicting microstructural evolution during tension was extracted for the CoCrFeNi HEA at three typical temperatures and three tensile *** model highlighted the importance of the body-centered cubic structure in the evolutionary process.

关键词： high-entropy alloy data-driven method microstructure evolution multiphase structure molecular dynamics simulation

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Chemical characteristics of aerosols at coastal station in Hong kong.Ⅱ. Environmental behavior of trace elements during the April 1995 to April 1996

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Journal of Environmental Sciences 2004年第2期16卷 212-221页

作者： k.S.Lam Z.L.Cheng S.C.kot C.W.Tsang Department of Civil and Structural Engineering the Hong Kong Polytechnic UniversityResearch Center for Eco-Environmental Sciences Chinese Academy of SciencesDepartment of Mechanical Engineering The Hong Kong University of Science & Technology Clear Water BayDepartment of Applied Biology and Chemical Technology the Hong Kong Polytechnic University Hung Hom Hong Kong ChinaBeijing 100085 ChinaHong Kong ChinaHung Hom Hong Kong China

An one-year of sampling aerosol program was carried out during the period of April 1995 to April 1996 at coastal region, Cape D′Aguilar, in Hong kong. The trace element composition of aerosol particles(TSP and PM 10 ) were measured and analyzed by using the Instrumental Neutron Activation Analysis(INAA) and Inductive Couple Plasma-Mass Spectrometry(ICP-MS) techniques. The results showed that the polluted elements such as: V, Zn, As, Pb, Cd, Sb, I, Se, Bi, with high enrichment factor(E.F) values, are derived from anthropogenic sources, while Sc, Al, Fe, Mn, Sm, La, Sr are less than 10 in E.F, these elements are related the crust and soil. The concentration of the trace elements are present seasonal variation i.e. summer low and winter high, whereas the V or noncrustal V(V *) present summer high and winter low, this phenomenon might be explained by local or regional oil combustion sources. Use three type of elemental ratio, e.g. La/Sm, Mn */V * and Bi/Al indicate that both TSP and PM 10 of La/Sm ratios are mainly related to soil and dust, Mn */V * are probably represent fossil combustion and Bi/Al are possibly associated with refuse incineration, ferromanganese alloys and aluminum production. The varimax rotation factor analysis for trace elements was performed. By means of the absolute principal component analysis(APCA) and multiple regression, the contribution of trace elements to possible sources and overall means of trace elements were estimated. The results showed that the present station is impacted by the anthropogenic species, although the quantities are different during the summertime and wintertime.

关键词： TSP PM 10 trace elements enhancement factor element ratios seasonal variation factor analysis

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First-principles study of structural,electronic,and optical properties of cubic InAs_xN_yP_(1-x-y) triangular quaternary alloys

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Chinese Physics B 2017年第1期26卷 425-432页

作者： I Hattabi A Abdiche F Soyalp R Moussa R Riane k Hadji S Bin-Omran R khenata Laboratoire synthese et Catalyse Ibn Khaldoun Universite of Tiaret Tiaret 14000 Algeria Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M) Departement de Technologie Universite de Mascara Mascara 29000 Algeria Department of Physics Faculty of Education Yuzuncu Ytl University 65080 Van Turkey Science and Technology D6partement Ibn khaldoun Universite de Tiaret Tiaret 14000 Algeria Department of Physics and Astronomy College of Science King Sand University Riyadh 11451 Saudi Arabia

In this paper, we investigated the structural, electronic and optical properties of InAs, InN and InP binary compounds and their related ternary and quaternary alloys by using the full potential linearized augmented plane wave（FP-LAPW）method based on density functional theory（DFT）. The total energies, the lattice parameters, and the bulk modulus and its first pressure derivative were calculated using different exchange correlation approximations. The local density approach（LDA） and Tran–Blaha modified Becke–Johnson（TB-m BJ） approximations were used to calculate the band *** variations of the lattice parameters, the bulk modulus and the band gap with compositions x and y are ***, the optical properties and the dielectric function, refractive index and loss energy were computed. Our results are in good agreement with the validated experimental and theoretical data found in the literature.

关键词： density functional theory full potential linearized augmented plane wave Tran–Blaha modified Becke–Johnson approximations InAsxNyP1-x-y

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