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left-handed properties of a composite structure with metallic wires in a homogeneous Lorentz medium

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International Journal of Minerals,Metallurgy and Materials 2012年第2期19卷 159-164页

作者： Yang bai Fang xu Li-jie Qiao Key Laboratory of Environmental Fracture(Ministry of Education) University of Science and Technology BeijingBeijing 100083China

The electromagnetic properties of a composite structure with metallic wires in a Lorentz medium were studied. The results show that the electromagnetic properties of the medium host influence the plasma resonance of metallic wires and the left-handed character of the composite. The plasma frequency of metallic wires reduces with the rise of permittivity or permeability of the medium host. Also, the negative permeability of the medium can destroy the wires’ plasma resonance and prevent the realization of left-handed properties. The high loss of medium permittivity or permeability also inhibits the metallic plasma resonance. The negative influence of the media host on the left-handed properties of the composite structure can be effectively reduced by proper structure design, such as introducing a nonmagnetic medium in the host or using an anisotropic medium.

关键词： electromagnetic waves left-handed materials plasma resonance electromagnetic interaction

Deformation, Phase Transformation and Recrystallization in the Shear Bands Induced by High-Strain Rate Loading in Titanium and Its Alloys

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Journal of Materials Science & Technology 2006年第6期22卷 737-746,I0003,I0004页

作者： Yongbo xu Yilong bai M.A.Meyers Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Laboratory for Non-linear Mechanics of Continuous Media Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA 920930-0411 USA

α-titanium and its alloys with a dual-phase structure （α＋β） were deformed dynamically under strain rate of about 10^4 s^-1. The formation and microstructural evolution of the localized shear bands were characterized by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results reveal that both the strain and strain rate should be considered simultaneously as the mechanical conditions for shear band formation, and twinning is an important mode of deformation. Both experimental and calculation show that the materials within the bands underwent a superhigh strain rate （9×10^5 S^-1） deformation, which is two magnitudes of that of average strain rate required for shear band formation; the dislocations in the bands can be constricted and developed into cell structures; the phase transformation from α to α2 within the bands was observed, and the transformation products （α2） had a certain crystallographic orientation relationship with their parent; the equiaxed grains with an average size of 10 μm in diameter observed within the bands are proposed to be the results of recrystallization.

关键词： Localized shear bands Microstructure Dislocations Twinning Phase transformation Recrystallization

Thermal Performance and Mechanics Characteristic for Double Layer Microchannel Heat Sink

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Journal of Thermal Science 2019年第2期28卷 271-282页

作者： xu Yupeng GONG Liang LI Yongtong bai Zhang xu Minghai Department of Energy & Power Engineering China University of Petroleum (East China)

Double layer micro-channel heat sink(DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overall stability. In this paper, two optimized designs of DLMCHS with cutting baffles on top and bottom layers are presented based on the traditional DLMCHS. The heat transfer and thermal stress performance are numerically analyzed and compared with the traditional DLMCHS. The results indicate that cutting baffles of micro-channels remarkably improves heat transfer and thermal stress performance. The optimized design with cutting baffles on the bottom layer decreases thermal strain but deteriorates heat transfer performance. The model with cutting baffles on the top layer has better combined thermal strain and heat transfer performance, which reduces thermal strain by about 1.5 times and enhances heat transfer by about 26.5%. For the design with cutting baffles on the top board, adding metal foam in the inlet collector can decrease the total minimum thermal strain by 51.4% and maximum temperature by 1.4 K, and increase the Nusselt number by 15%. These results indicate that DLMCHS with cutting baffles on the top layer has great potential for thermal managements on electronic devices with high power density.

关键词： double layer micro-channel heat sink thermal strain thermal performance optimized design

Microfluidic reactor with immobilized enzyme-from construction to applications:A review

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Chinese Journal of Chemical Engineering 2021年第2期34卷 136-145页

作者： Han Zhang Yunpeng bai Ning Zhu Jianhe xu State Key Laboratory of Bioreactor Engineering East China University of Science and TechnologyShanghai 200237China College of Biotechnology and Pharmaceutical Engineering Nanjing Tech UniversityNanjing211800China

Microfluidic,as the systems for using microchannel(micron-or sub-micron scale)to process or manipulate microflow,is being widely applied in enzyme biotechnology and *** immobilized enzyme reactor(MIER)is a tool with great value for the study of catalytic property and optimal reaction parameter in a flourishing and highly producing *** view of its advantages in efficiency,economy,and addressable recognition especially,MIER occupies an important position in the investigation of life science,including molecular biology,bioanalysis and biosensing,biocatalysis *** of enzymes can generally improve their stability,and upon most occasions,the immobilized enzyme is endowed with *** this review,the enzyme immobilization techniques applied in MIER will be discussed,followed by summarizing the novel developments in the field of MIER for biocatalysis,bioconversion and *** preponderances and deficiencies of the current state-of-the-art preparation ways of MIER are peculiarly *** addition,the prospects of its future study are outlined.

关键词： Microfluidic immobilized enzyme reactor Immobilization strategies Biocatalysis Bioconversion Bioanalysis

Method for solving dynamic equilibrium equations based on displacement excitation

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Earthquake Engineering and Engineering Vibration 2020年第2期19卷 423-433页

作者： xu Guolin Zhang Lingxin bai Yashuang Sun Hao Institute of Civil Engineering Southwest Forestry UniversityKunming 650224China Institute of Engineering Mechanics China Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration Harbin 150080China School of Information and Electrical Engineering Ludong UniversityYantai 264025China

Mode superposition is a widely used method for solving the dynamic equilibrium equation in structural dynamic ***,the accuracy of this method may be reduced when the dynamic equilibrium equations are set up using displacement excitation.A new method for developing solutions for dynamic equilibrium equations based on displacement excitation is *** dynamic equilibrium equation is decomposed into two parts,namely displacement excitation and velocity excitation,and precise integration and mode superposition methods are combined to solve the *** vectors are then used to calculate the static response of the truncated modes of the structure,and a method for determining the number of participating modes is *** multi-degree-of-freedom systems as two computational examples,the differences in the structural responses obtained from the displacement excitation and acceleration excitation are compared and *** is shown that the new solution method generates consistent accuracy between the displacement excitation and acceleration excitation.

关键词： displacement excitation precise integration structural seismic response

The transition to turbulent fluidization in a gas-solid fluidized bed operating from ambient temperature to 1600℃

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Particuology 2024年第10期93卷 111-124页

作者： Qingjin Zhang Liangliang Fu Guangwen xu Dingrong bai Key Laboratory on Resources Chemicals and Material of Ministry of Education Shenyang University of Chemical TechnologyShenyang110142China School of Materials Science and Engineering Shenyang University of TechnologyShenyang110142China Ordos Laboratory Ordos017010China

Turbulent fluidized bed proves effective in industrial processes due to superior heat and mass transfer and chemical reaction performance. However, understanding the transition to turbulent fluidization remains limited, especially at temperatures exceeding 1000 ℃, making it challenging to develop high-temperature fluidized bed applications. This paper presents an experimental investigation on the turbulent fluidization onset velocity (U_(c)), measured in a 30 mm diameter bed using corundum particles with average diameters from 0.68 mm to 1.58 mm in temperatures from ambient to 1600 ℃. Experimental results reveal that U_(c) increases with temperature up to 600 ℃, stabilizes within the 600–1200 ℃ range, and then decreases above 1200 ℃, demonstrating the varying relative significance of hydrodynamic and interparticle forces at different temperatures. To help design and operate high-temperature applications of turbulent fluidization, we developed U_(c) correlations based on experimental data from both literature sources and this study, covering temperatures of up to 1600 ℃ and particles of Groups A to D.

关键词： High-temperature fluidized beds Turbulent fluidization Transition velocity Pressure fluctuations Hydrodynamic forces Interparticle forces

Tunable luminescence in co-doped Zn3Al2Ge2O10:Cr3+by controlling crystal field splitting and nephelauxetic effect

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Journal of Rare Earths 2020年第12期38卷 1265-1272页

作者： Qiongyu bai Suling Zhao Zheng xu Panlai Li Key Laboratory of Luminescence and Optical Information(Beijing Jiaotong University) Ministry of EducationBeijing 100044China Institute of Optoelectronics Technology Beijing Jiaotong UniversityBeijing 100044China College of Physics Science&Technology Hebei Key Lab of Optic-Electronic Information and MaterialsHebei UniversityBaoding 071002China

Ce3+/Dy3+/Tb3+/Eu3+/Mn2+and Cr3+ions co-doped Zn3 Al2 Ge2 O10 phosphor were prepared by a hightemperature solid-state method.X-ray diffraction patterns prove the cubic phase structure of prepared Zn3 Al2 Ge2 O10 phosphor,Emission,excitation spectra and decay curves confirm the tunable *** degrees of the decrease of emission FWHM in Zn3 Al2 Ge2 O10:0.02 Cr3+,RE(RE=Ce3+,Dy3+,Tb3+,Eu3+)and Zn3 Al2 Ge2 O10:0.02 Cr3+,Mn2+are *** reason of variable FWHM is the effect of crystal field splitting and nephelauxetic effect,and the nephelauxetic effect is ***,the emission FWHM decreases with the increasing concentration of Mn2+/Tb3+/Eu3+in Zn3 Al2 Ge2 O10:0.02 Cr3+,and for Zn3 Al2 Ge2 O10:0.02 Cr3+,Ce3+and Zn3 Al2 Ge2 O10:0.02 Cr3+,Dy3+,it is a *** variation of Zn3 Al2 Ge2 O10:0.02 Cr3+,Tb3+is more obvious than that of Zn3 Al2 Ge2 O10:0.02 Cr3+,Eu3+,because Tb3+ion has smaller ***,the tunable luminescence of Cr3+can be realized by co-doping different *** these phosphors have potential applications in light-emitting diodes for plant growth.

关键词： Iuminescence Zn3Al2Ge2O10:Cr3+ Co-doping Ions Rare earths

Phase-field-lattice Boltzmann simulation of dendrite growth under natural convection in multicomponent superalloy solidification

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Rare Metals 2020年第2期39卷 147-155页

作者： Cong Yang Qing-Yan xu bai-Cheng Liu Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy *** this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy *** the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt *** solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth *** the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were *** is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.

关键词： Dendrite growth Natural convection Phasefield model Lattice Boltzmann method

Hot Corrosion Resistance of TB8 Titanium Alloy after ECAP and Heat Treatment

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1440-1448页

作者： LI Shuaidi xu Xiaojing bai Xiang CAO Bin Institute of Advanced Manufacturing and Modern Equipment Technology Jiangsu UniversityZhenjiang 212013China

The metastableβtitanium alloy TB8(Ti-12.76Mo-2.13Nb-2.73A1-0.16Si)was used as the original material,and the secondary processing method combining equal channel angular pressing(ECAP)and heat treatment was *** the help of optical microscope(OM),scanning electron microscope(SEM)and X-ray diffractometer(XRD),the corrosion behavior of TB8 titanium alloy after different secondary processing(800℃/850℃solid solution-520℃aging,ECAP-800℃/850℃solid solution-520℃aging,and800℃/850℃solid solution-ECAP-520℃aging)was *** experimental results show that the hot corrosion products of the six samples are similar,mainly Na_(2)Si_(2)O_(5),MoS_(2),TiCl_(2),Ti(SO_(4))_(2),and *** to the grains of the TB8 titanium alloy treated by 850℃solid solution-ECAP-520℃aging are obviously refined,the surface structure is the most smooth and dense,forming a continuous Al2O3protective film,and the surface defects are the least after *** corrosion layer thickness is the lowest(102.3μm),only 36.5%-81.4%of that of other secondary processing titanium *** addition,the corrosion kinetics curves of the six materials all follow parabolic laws,and the minimum corrosion weight gain of the samples after 850℃solutionECAP-520℃aging treatment is 0.7507 mg·mm^(-2),showing better hot corrosion resistance.

关键词： TB8 ECAP heat treatment hot corrosion resistance