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Bio-replicated forming of the biomimetic drag-reducing surfaces in large area based on shark skin

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Chinese Science Bulletin 2008年第10期53卷 1587-1592页

作者： HAN Xin ZHANG deyuan li Xiang li YuanYue School of Mechanical Engineering and Automation Beihang University Beijing 100083 China

On the investigation of biomimetic drag-reducing surface, direct replication of the firm scarfskins on low-resistance creatures to form biomimetic drag-reducing surfaces with relatively vivid morphology relative to the living prototype is a new attempt of the bio-replicated forming *** shark skin as the bio-replication template, the hot embossing method was applied to the microreplication of its outward morphology. Furthermore, the skins were jointed together to form the drag-reducing surface in large area. The results of the resistance measurements in a water tunnel according to the flat-plate sample pieces have shown that the biomimetic shark-skin coating fabricated by the bio-replicated forming method has significant drag reduction effect, and that the drag reduction efficiency reached 8.25% in the test conditions.

关键词：鲨鱼皮生物复制成型热压纹生物学

Jackknife empirical likelihood test for the equality of degrees of freedom in t-copulas

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Science China Mathematics 2020年第4期63卷 789-822页

作者： Yanxi Hou deyuan li Aiai liu liang Peng School of Data Science Fudan UniversityShanghai 200433China School of Management Fudan UniversityShanghai 200433China Department of Mathematics Tongji UniversityShanghai 200092China Department of Risk Management and Insurance Georgia State UniversityAtlantaGA 30303USA

It has been argued that fitting a t-copula to financial data is superior to a normal copula. To overcome the shortcoming that a t-copula only has one parameter for the degrees of freedom, the t-copula with multiple parameters of degrees of freedom has been proposed in the literature, which generalizes both the t-copulas and the grouped t-copulas. like the inference for a t-copula, a computationally efficient inference procedure is to first estimate the correlation matrix via Kendall's τ and then to estimate the parameters of degrees of freedom via pseudo maximum likelihood estimation. This paper proposes a jackknife empirical likelihood test for testing the equality of some parameters of degrees of freedom based on this two-step inference procedure, and shows that the Wilks theorem holds.

关键词： jackknife empirical likelihood t-Copula

Application of autoregressive tail-index model to China’s stock market

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Statistical Theory and Related Fields 2021年第1期5卷 31-34页

作者： Jingyu Ji deyuan li School of Data Science Fudan UniversityShanghaiPeople’s Republic of China School of Management Fudan UniversityShanghaiPeople’s Republic of China

We congratulate Professor Zhengjun Zhang for a topnotch contribution to the literature and thank the editor for the invitation to participate in the discussion of the excellent review ***(2020)provides an informative summary ofmodelling systematic riskwith nonlinear time seriesmodels and tail dependencemeasures based on extreme *** the current era,where risk management is becoming more and more important,this review paper is timely and will provide the impetus for future research in this and broader areas.

关键词： editor becoming extreme

Impact of hot alkali modification conditions on secondary structure of peanut protein and embedding rate of curcumin

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Food Science and Human Wellness 2019年第3期8卷 283-291页

作者： Wei li Shugang li Yong Hu Mengzhou Zhou Chao Wang Dongsheng li deyuan li Hubei University of Technology Wuhan430068China Hubei Cooperative Innovation Center for Industrial Fermentation Wuhan430068China Function Food Engineering Center of Hubei province Hubei University of Chinese MedicineWuhan430068China

This study aimed to modify isolated and extracted peanut protein with hot alkali to study the impact of pH,heating temperature,processing time and other alkali liquor conditions on the molecular structure of the *** was loaded in modified peanut *** results of the study are as follows:Within the alkaline range of 8lices andβ-sheets gradually decreased with increasing pH,while that of random coils gradually increased with increasing pH,reaching a maximum 11.24±0.87%when the pH was 11(plices and AAR gradually decreased with increasing heating temperature;they remained unchanged when the heating temperature was 90℃,and then decreased to(10.41±1.18%;plices decreased from 11.83±1.04%to 10.75±2.34%with increased heating time(pli modification of peanut protein as followed:heating temperature of 90℃,heating time of 20 min and a pH of alkali liquor of *** these optimum conditions,the embedding rate of curcumin by the modified protein can reach 88.32±1.29%.

关键词： Curcumin Embedding rate Hot alkali modification Peanut protein Secondary structure

Creep behavior and effect factors of a TiAl–Nb alloy at high temperature

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Progress in Natural Science:Materials International 2021年第3期31卷 477-485页

作者： Shunke Zhang Sugui Tian Gengyu li Ning Tian Fangwei Jin Huichen Yu Xiaoxia Lv Guangyan Wang deyuan li Shenyang University of Technology Guizhou University of Engineering Science Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation Science and Technology on Advanced High Temperature Structural Materials Laboratory AVIC Beijing Institute of Aeronautical Materials

The effect of solution treatment on the microstructure and creep properties of forged TiAl-Nb alloys was *** results showed that the microstructure of forged alloy mainly consisted of γ/αlamellar colonies and fine equiaxed recrystallized γ/α*** the solution treatment the microstructure of the alloy transformed into a fully lamellar structure due to the lamellar colonies growth by consuming equiaxed *** with the forged alloy the creep life of the solution treated alloy at 800℃/220 MPa increased from 116 h to 339 *** better creep resistance may be attributed to the transform of fine equiaxed γ/αgrain to the lamellar colonies with serrated grain boundaries due to the solution *** deformation mechanism of the solution treated alloy during creep is considered to be dislocation slipping within the lamellar γ/αphases,and the dislocation movement may be hindered by the γ/αinterface and the formation of dislocation *** interaction of the dislocations with the tangles may increase the resistance of the dislocation motion and hence improve the creep resistance of the *** was found that during the creep of the forged alloys the cracks mainly initiated at the equiaxed grain,and in the solution treated alloy the cracks initiated at the grain *** creep continued the cracks propagated and connected to each other,leading to the damage and rupture of the forged and solution treated alloys.

关键词： Forged TiAl–Nb alloy Solution treatment Microstructure Creep Deformation and damage

Microstructures and formation mechanism of hypoeutectic white cast iron by isothermal electromagnetic rheocast process

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China Foundry 2010年第2期7卷 113-116页

作者： Zhang Wanning Song Dan Zhang Hongbing li deyuan Yuan Xiaoguang Qiu Keqiang Shenyang Government Investment Project Evaluation Center Shenyang 1100141 China School of Materials Science and Engineering Shenyang University of Technology Shenyang 110870 China

An investigation was made on the evolution of microstructures of hypoeutectic white cast iron slurry containing 2.5wt.%C and 1.8wt.%Si produced by rheocasting in which the solidifying alloy was vigorously agitated by electromagnetic stirrer during isothermal cooling *** results indicated that under the proper agitating temperatures and speeds applied,the dendrite structures in white cast iron slurry were gradually evolved into spherical structures during a certain agitating *** also revealed that the bent dendrites were formed by either convection force or by the growth of the dendrites themselves in the bending direction;then,as they were in solidifying,they were gradually being alternated into separated particles and into more spherical structures at the end of the isothermal cooling ***,the dendrites were granulated as the bending process proceeding,which suggested that they were caused by unwanted elements such as sulfur and phosphor usually contained in engineering cast ***-ow of the melt caused corrosion on the dendritic segments where they were weaker in strength and lower in melting temperature because of higher concentration of sulfur or *** the granulation process for such dendrites formed in the melt became possible under the ***,dendrite fragments are another factors considerable to function for spherical particles formation.A new mechanism,regarding to the rheocast structure formation of white cast iron,was suggested based on the structural evolution observed in the study.

关键词： white cast iron rheocasting structural evolution structures formationmechanism

Deformation and damage behaviors of as-cast TiAl-Nb alloy during creep

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Progress in Natural Science:Materials International 2018年第5期28卷 618-625页

作者： Shunke Zhang Sugui Tian Xiaoxia Lv Huichen Yu Ning Tian Zehui Jiao Guoqi Zhao deyuan li Guizhou University of Engineering Science Shenyang University of Technology AECC Key Laboratory of Science and Technology on Materials Testing and Evaluation National Key Laboratory of Science and Technology on Advanced High Temperature Structure Materials AECC Beijing Institute of Aeronautical Materials

By means of creep properties measurement and microstructure observation,the deformation and damage behavior of an as-cast TiAl-Nb alloy during creep at temperature near 750°C were *** results showed that the microstructure of the alloy consisted of lamellarγ/α;phase,and the boundaries consisted ofγphase located in between lamellarγ/α;phases with different *** the latter stage of creep,the dislocation networks appeared in the interfaces of lamellarγ/α;phases due to the coarsening of them,which made the coherent interface transforming into the semi-coherent one for reducing its adhesive *** deformation mechanism of the alloy during creep was twinning and dislocations slipping within lamellarγ/α;*** the later period of creep,significant amount of dislocations plied up in the interfaces of lamellarγ/α;phases,which may cause the stress concentration to promote the initiation and propagation of the cracks along the lamellarγ/α;interfaces perpendicular to the stress ***,some cracks on the various cross-sections were connected by tearing edge along the direction of maximum shear stress,up to the creep fracture,which is considered to be the damage and fracture mechanism of alloy during creep at 750°C.

关键词： TiAl-Nb alloy Creep Dislocation network Deformation mechanism Fracture mechanism

Solution-processed lead-free bulk 0D Cs3Cu2I5 single crystal for indirect gamma-ray spectroscopy application

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Photonics Research 2021年第3期9卷 351-356页

作者： Qiang Xu Juan Wang Qindong Zhang Xiao Ouyang Maheng Ye Weiting Xie Xuewen Yan deyuan li Xiaoping Ouyang Xiaobing Tang Xiaodong Zhang Department of Nuclear Science and Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China Shaanxi Engineering Research Center of Controllable Neutron Source School of ScienceXijing UniversityXi'an 710123China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China China Institute for Radiation Protection Taiyuan 030012China Northwest Institute of Nuclear Technology Xi'an 710024China

Bulk scintillators that are with high density,low cost,and fine pulse-height energy spectral resolution,and are nonhygroscopic and user friendly,are desired for high-energy gamma-ray spectroscopy ***,low-cost solution-processed perovskite nanoscintillators have been demonstrated with outstanding performances for indirect low-energy X-ray detection;however,the stability and thickness are not suitable for high-energy gamma-ray ***,we report scintillation performances of a low-cost solution-processed bulk 0D Cs3Cu2I5 single *** self-trapped exciton emission results in a large Stokes shift (109 nm) that is reabsorption free.A broad X-ray excited emission matches well with the sensitivity of a silicon *** unique Cs+ surrounded isolated [Cu2I5]3-cluster scintillator provides ultra-stability in air and strong radiation hardness under high-dose gammaray exposure from a 60Co *** solution-processed Cs3Cu2I5 scintillator is expected with low-cost and has detection performances comparable to commercial alkali-halide scintillator products.

关键词： spectroscopy stability crystal

In-situ deposition of Pd/Pd_(4)S heterostructure on hollow carbon spheres as efficient electrocatalysts for rechargeable li-O_(2)batteries

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Chinese Chemical Letters 2021年第6期32卷 2086-2090页

作者： Xiaomeng liu Qishun Huang Jun Wang Lanling Zhao Haoran Xu Qing Xia deyuan li Lei Qian Huaisheng Wang Jintao Zhang Key Laboratory for liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJi'nan 250061China Key Laboratory for Colloid and Interface Chemistry(Ministry of Education) School of Chemistry and Chemical EngineeringShandong UniversityJi'nan 250061China School of Physics Shandong UniversityJi'nan 250100China School of Chemistry and Chemical Engineering Liao Cheng UniversityLiaocheng 252059China

The sluggish kinetics of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)have always restricted the development of lithium oxygen batteries(LOBs).Herein,hollow carbon spheres loaded with Pd/Pd_(4)S heterostructure(Pd/Pd_(4)S@HCS)were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in *** the welldispersed Pd/Pd_(4)S nanoparticles,the hierarchical composite with large specific surface area offers favorable transport channels for ions,electron and ***,the Pd/Pd_(4)S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the ***,the LOBs with Pd/Pd_(4)S@HCS as cathode catalyst show improved specific capacities,good rate ability and stable cycling performance.

关键词： Hierarchical porous carbon sphere Pd/Pd_(4)S heterostructure In-situ deposition Enhanced electrocatalytic activity lithium-oxygen batteries