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Simulating Three-Dimensional Free Surface Viscoelastic Flows using Moving Finite Difference Schemes

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Numerical Mathematics(Theory,Methods and Applications) 2011年第1期4卷 92-112页

作者： yubo zhang Tao Tang Department of Computer Science 2063 Kemper HallUniversity of California at DavisOne Shields AvenueDavisCA 95616-8562USA Department of Mathematics Hong Kong Baptist UniversityKowloon TongKowloonHong Kong

An efficient finite difference framework based on moving meshes methodsis developed for the three-dimensional free surface viscoelastic flows. The basic modelequations are based on the incompressible Navier-Stokes equations and the Oldroyd-Bconstitutive model for viscoelastic flows is adopted. A logical domain semi-Lagrangianscheme is designed for moving-mesh solution interpolation and convection. Numericalresults show that harmonic map based moving mesh methods can achieve better accuracy for viscoelastic flows with free boundaries while using much less memory andcomputational time compared to the uniform mesh simulations.

关键词： Moving mesh free surface viscoelastic flow solution interpolation

Investigations into the perplexing interrelationship of the Genus Takifugu Abe, 1949 (Tetraodontiformes, Tetraodontidae)

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Chinese Science Bulletin 2008年第2期53卷 233-244页

作者： zhang yubo HE ShunPing Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China Graduate University of Chinese Academy of Sciences Beijing 100039 China

The phylogenetic relationships within the genus Takifugu Abe, 1949 (Tetraodontiformes, Tetraodonti- dae) remain unresolved. Because of the use of Takifugu as model organisms, the resolution of these relationships is crucial for the interpretation of evolutionary trends in biology. Pufferfishes of this ge- nus are comprised of a comparatively small number of species and are mainly distributed along the coastal region of the western part of the Sea of Japan and the coastline of China. Mitochondrial gene sequences were employed to test the phylogenetic hypotheses within the genus. Seventeen species of the genus were examined. Molecular phylogenetic trees were constructed using the maximum parsi- mony, neighbor-joining, maximum likelihood and Bayesian methods. Our hypothesis of internal relationships within the genus differs from previous hypotheses. Our results indicate that (1) the genus Takifugu is a monophyletic assemblage; (2) the genus is divided into 6 subgroups based on the mo- lecular data; and (3) there is low genetic diversity among the species within this genus. In addition, speciation within Takifugu appears to be driven by hybridization and isolation by distribution. Our re- sults also suggested that the taxonomy in the genus should be clarified based on both molecular and morphological data.

关键词：系统发育细胞色素b基因 rRNA基因暗纹东方鲀

Efficient and Secure Authentication Scheme with Conditional Privacy-Preserving for VANETs

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Chinese Journal of Electronics 2016年第5期25卷 950-956页

作者： XIE Yong WU Libing zhang yubo SHEN Jian School of Computer Science Wuhan University School of Information and Engineering Jingdezhen Ceramic Institute State Key Laboratory of Software Engineering Wuhan University School of Computer and Software Nanjing University of Information Science and Technology

The goal of authentication scheme for Vehicular ad hoc networks(VANETs) is to ensure reliability and integrity of message. Due to the timeliness of traffic-related messages and the highly dynamic nature of VANETs, it still is a challenge to solve the three key issues simultaneously, i.e. security, efficiency and conditional privacy-preserving, on the design of authentication scheme for VANETs. To address this challenge, an efficient Conditional privacy-preserving authentication(CPPA) scheme is proposed in this paper. Compared with the most recent proposed CPPA schemes, our proposed scheme markedly decreases the computation costs of the message-signing phase and the message verification phase, while satisfies all security requirements of VANETs and provides conditional privacy-preserving.

关键词： VANETs Authentication scheme Security Conditional privacy-preservation Efficiency

Semisolid-rolling and annealing process of woven carbon fibers reinforced Al-matrix composites

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Journal of Materials Science & Technology 2017年第7期33卷 623-629页

作者： Junjia zhang Shichao Liu Yiping Lu Li Jiang yubo zhang Tingju Li Key Laboratory of Solidification Control and Digital Preparation Technology （Liaoning Province） School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China

Semisolid-rolling method was successfully developed to prepare the Ni-coated woven carbon fibers reinforced Al-matrix composite. Due to the appropriate matrix flowability and rolling pressure, the Al-matrix could infiltrate into the woven fibers sufficiently and attach to the reinforcements closely forming a smooth interface. The rolling speed of 4 rad/min offered a subtle equilibrium between the heat transfer and the material deformation. The covering matrix should be controlled at semisolid state to provide a better infiltration behavior and a protective effect on the carbon fibers. With the addition of fibers, an improvement for more than 25% was obtained in the bending strength of the materials. Furthermore, the woven carbon fibers could strengthen the composite in multiple directions, rather than only along the fiber longitudinal directions. The annealing process promoted the Ni coating to react with and to diffuse into the matrix, resulted in an obvious increase of the bending strength.

关键词： Metal-matrix composites Woven carbon fiber Semisolid-rolling process Annealing Mechanical property

Temporal and Spatial Distribution of the Late Devonian (Famennian) Strata in the Northwestern Border of the Junggar Basin, Xinjiang, Northwestern China

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1413-1437页

作者： MA Xueping zhang Meiqiong ZONG Pu zhang yubo Lü Dan The Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University Beijing 100871 China Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

The base of the Saerba Member （Mbr） of the Hongguleleng Formation （Fm.） probably lies in the Famennian Palmatolepis crepida Zone; the Longkou Mbr is probably a sedimentary wedge that thins out northwards; the Duguer Mbr has an approximate age from the upper part of the Pa. marginifera Zone or the Lower Pa. rugosa trachytera Zone through the top of the Pa. perlobata postera Zone; the Wulan Mbr has an age approximately corresponding to the whole Pa. gracilis expansa Zone. In the Bulongguoer section, the Lower Mbr of the Hongguleleng Fro. corresponds to Famennian Pa. crepida Zone through Pa. marginifera Zone; the Middle Mbr probably ranges from the Pa. r. trachytera Zone through the Pa. g. expansa Zone. The basal Namu Mbr of the Heishantou Fm. is probably the product during and after the Hangenberg Event in the upper part of the Siphonodellapraesulcata Zone, which is still within the Devonian. In this context, the underlying Chasi Mbr may approximately correspond to the lower part of the S. praesulcata Zone （before the Hangenberg Event）. Lateral distribution of strata indicates that the Upper Devonian in the Gennaren and Saerba areas each constitutes a structure of syncline, which differs from the previous recognition of a monocline structure.

关键词： Junggar Bulongguoer Hongguleleng Formation Heishantou Formation "Hebukehe"Formation Xinjiang

Effects of Strain Rate and Fiber Content on the Dynamic Mechanical Properties of Sisal Fiber Cement-Based Composites

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Journal of Renewable Materials 2023年第1期11卷 393-410页

作者： yubo zhang Ping Lei Lina Wang Jiqing Yang Facuty of Architecture and Civil Engineering Yunnan Agricultural UniversityKunming650000China

In this paper,a split Hopkinson pressure bar(SHPB)was used to investigate the dynamic impact mechanical behavior of sisal fiber-reinforced cement-based composites(SFRCCs),and the microscopic damage evolution of the composites was analyzed by scanning electron microscopy(SEM)and energy-dispersive X-ray spectrome-try(EDS).The results show that the addition of sisal fibers improves the impact resistance of cement-based composite *** with ordinary cement-based composites(OCCs),the SFRCCs demonstrate higher post-peak strength,ductility,and energy absorption capacity with higher fiber ***,the SFRCCs are strain rate sensitive materials,and their peak stress,ultimate strain,and energy integrals all increase with increasing strain *** the perspective of fracture failure characteristics,the failure of OCCs is dominated by the brittle failure of crystal *** contrast,the failure mode of the SFRCCs changes to microscale matrix cracks,multi-scale pull-out interface debonding of fibers(fine filaments and bundles),and mechanical *** research provides an experimental basis for the engineering application of high-performance and green cement-based composites.

关键词： Sisal fiber cement-based composites SHPB energy integration microstructure damage evolution law

Assessment of fatigue life of remanufactured impeller based on FEA

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Frontiers of Mechanical Engineering 2016年第3期11卷 219-226页

作者： Lei XU Huajun CAO Hailong LIU yubo zhang The State Key Laboratory of Mechanical Transmission Chongqing University Chongqing 400030 China National Key Laboratory for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 China

Predicting the fatigue life of remanufactured centrifugal compressor impellers is a critical problem. In this paper, the S-N curve data were obtained by combining experimentation and theory deduction. The load spectrum was compiled by the rain-flow counting method based on the comprehensive consideration of the centrifugal force, residual stress, and aerodynamic loads in the repair region. A fatigue life simulation model was built, and fatigue life was analyzed based on the fatigue cumulative damage rule. Although incapable of providing a high-precision predic- tion, the simulation results were useful for the analysis of fatigue life impact factors and fatigue fracture areas. Results showed that the load amplitude greatly affected fatigue life, the impeller was protected from running at over-speed, and the predicted fatigue life was satisfied within the next service cycle safely at the rated speed.

关键词： remanufactured impeller fatigue life impeller failures finite element analysis (FEA)

Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 61-72页

作者： yubo zhang Hongyun Luo Qunpeng Zhong Honghui Yu Jinlong Lv Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics The Collaborative Innovation Center for Advanced Aero-Engine (CICAAE) Beijing University of Aeronautics and Astronautics Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beijing University of Aeronautics and Astronautics China Waterborne Transport Research Institute Beijing Key Laboratory of Fine Ceramics Institute of Nuclear and New Energy Technology Tsinghua University

The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films formed on asreceived and sensitized AISI304 stainless steel in borate bu er solution were evaluated in this paper. The degree of sensitization and corrosion resistance of AISI304 stainless steels was evaluated by double loop electrochemical potentiodynamic reactivation and electrochemical impedance spectroscopy. The passive films formed on the stainless steels were studied by XPS technique. It was found that as-received specimen had higher pitting corrosion potential and corrosion resistance than sensitized one. The Mott-Schottky results showed that sensitized stainless steel had more defects in the passive film than as-received one. The compositions of the passive films were mainly Cr and Fe oxides according to XPS results.

关键词： 304 stainless steel Sensitization Passive films XPS Impedance

Highly efficient emission and high-CRI warm white light-emitting diodes from ligand-modified CsPbBr_(3) quantum dots

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Opto-Electronic Advances 2022年第1期5卷 35-48页

作者： Dongdong Yan Shuangyi Zhao yubo zhang Huaxin Wang Zhigang Zang Key Laboratory of Optoelectronic Technology&Systems(Ministry of Education) Chongqing UniversityChongqing 400044China Department of Physics Southern University of Science and TechnologyShenzhen 518055China

All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding ***,their practical application is hindered by poor ***,we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr_(3) QDs by using 2-hexyldecanoic acid(DA)as a ligand to replace the regular oleic acid(OA)*** to the strong binding energy between DA ligand and QDs,the modified QDs not only show a high photoluminescence quantum yield(PLQY)of 96%but also exhibit high stability against ethanol and *** warm white light-emitting diodes(WLEDs)are constructed by combining lig-and modified CsPbBr_(3) QDs with red AgInZnS QDs on blue emitting InGaN chips,exhibiting a color rendering index of 93,a power efficiency of 64.8 lm/W,a CIE coordinate of(0.44,0.42)and correlated color temperature value of 3018 *** ad-dition,WLEDs based on ligand modified CsPbBr_(3) QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr_(3) *** combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr_(3) QDs are ideal for WLEDs application.

关键词： CsPbBr_(3)quantum dots ligand modification stability efficiency white light-emitting diodes