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International Journal of Minerals,Metallurgy and Materials 2019年第11期26卷 1450-1456页

作者： Ying Yan Guo-qiang Zhang li-jia chen Xiao-wu li Department of Materials Physics and Chemistry School of Materials Science and Engineeringand Key Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

To explore the specimen size effect of mechanical behavior of ultrafine-grained(UFG)materials with different structures,UFG Al sheets processed by equal channel angular pressing(ECAP)were selected as target materials and the dependency of tensile behavior on sheet thickness(t)was systematically *** strength and ductility of ECAPed UFG Al sheets were improved synchronously as t increased from 0.2 to 0.7 mm,and then no apparent change occurred when t reached to 0.7 and 1.0 *** corresponding microstructure evolved from dislocation networks in equiaxed grains into the walls and subgrains and finally into the dominated cells in elongated grains or ***,dense shear lines(SLs)and shear bands(SBs)were clearly observed and microvoids and cracks were initiated along SBs with the increase of *** observations indicated that the plastic deformation of UFG Al sheets was jointly controlled by shear banding,dislocation sliding,and grain-boundary ***,the propagation of SBs became difficult as t ***,the obtained results were discussed and compared with those of annealed UFG Al and UFG Cu.

关键词： ultrafine-grained pure Al specimen size effect strength ductility

Efficient design of rotary traveling wave oscillator array via geometric programming

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第12期10卷 1815-1823页

作者： li-jia chen Hua-feng ZHANG Jin-fang ZHOU Kang-sheng chen Department o fin formation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

This paper presents an efficient method for globally optimizing and automating component sizing for rotary traveling wave oscillator arrays. The lumped equivalent model of transmission lines loaded by inverter pairs is evaluated and posynomial functions for oscillation frequency, power dissipation, phase noise, etc. are formulated using transmission line theory. The re- sulting design problem can be posed as a geometric programJning problem, which can be efficiently solved with a convex opti- mization solver. The proposed method can compute the global optima more efficiently than the traditional iterative scheme and various design problems can be solved with the same circuit model. The globally optimal trade-off curves between competing objectives are also computed to carry out robust designs and quickly explore the design space.

关键词： Rotary traveling wave oscillator array (RTWOA) Clock distribution Transmission line resonator Global optimi-zation Geometric programming (GP)

Solar cycle prediction using a long short-term memory deep learning model

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Research in Astronomy and Astrophysics 2021年第1期21卷 119-126页

作者： Qi-Jie Wang jia-chen li liang-Qi Guo School of Geosciences and Info-Physics Central South UniversityChangsha 410083China

In this paper,we propose a long short-term memory(LSTM)deep learning model to deal with the smoothed monthly sunspot number(SSN),aiming to address the problem whereby the prediction results of the existing sunspot prediction methods are not uniform and have large *** method optimizes the number of hidden nodes and batch sizes of the LSTM network structures to 19 and 20,*** best length of time series and the value of the timesteps were then determined for the network training,and one-step and multi-step predictions for Cycle 22 to Cycle 24 were made using the well-established *** results showed that the maximum root-mean-square error(RMSE)of the one-step prediction model was6.12 and the minimum was only *** maximum amplitude prediction error of the multi-step prediction was 17.2%and the minimum was only 3.0%.Finally,the next solar cycles(Cycle 25)peak amplitude was predicted to occur around 2023,with a peak value of about *** accuracy of this prediction method is better than that of the other commonly used methods,and the method has high applicability.

关键词： Sun:solar activity Sun:sunspot number techniques:deep learning techniques:long short-term memory

3D Object Tracking with Adaptively Weighted Local Bundles

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Journal of Computer Science & Technology 2021年第3期36卷 555-571页

作者： jia-chen li Fan Zhong Song-Hua Xu Xue-Ying Qin School of Software Shandong UniversityJinan 250101China School of Computer Science and Technology Shandong UniversityQingdao 266237China College of Engineering and Computing University of South CarolinaColumbia 29208U.S.A.

The 3D object tracking from a monocular RGB image is a challenging *** popular color and edgebased methods have been well studied,they are only applicable to certain cases and new solutions to the challenges in real environment must be *** this paper,we propose a robust 3D object tracking method with adaptively weighted local bundles called AWLB tracker to handle more complicated *** bundle represents a local region containing a set of local *** alleviate the negative effect of the features in low-confidence regions,the bundles are adaptively weighted using a spatially-variant weighting function based on the confidence values of the involved energy ***,in each frame,the weights of the energy items in each bundle are adapted to different situations and different regions of the same *** show that the proposed method can improve the overall accuracy in challenging *** then verify the effectiveness of the proposed confidence-based adaptive weighting method using ablation studies and show that the proposed method overperforms the existing single-feature methods and multi-feature methods without adaptive weighting.

关键词： 3D tracking local bundle feature fusion confidence map

Variation of the uniaxial tensile behavior of ultrafine-grained pure aluminum after cyclic pre-deformation

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International Journal of Minerals,Metallurgy and Materials 2018年第6期25卷 663-671页

作者： Ying Yan li-jia chen Guo-qiang Zhang Dong Han Xiao-wu li Department of Materials Physics and Chemistry School of Materials Science and Engineering and Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education Northeastern University School of Materials Science and Engineering Shenyang University of Technology

To explore the influence of cyclic pre-deformation on the mechanical behavior of ultrafine-grained（UFG）materials with a high stacking fault energy（SFE）,UFG Al processed by equal-channel angular pressing（ECAP）was selected as a target material and its tensile behavior at different pre-cyclic levels D（D=N_i/N_f,where N_i and N_f are the applied cycles and fatigue life at a constant stress amplitude of 50 MPa,respectively）along with the corresponding microstructures and deformation features were systematically *** cyclic pre-deformation treatment on the ECAPed UFG Al led to a decrease in flow stress,and a stress quasi-plateau stage was observed after yielding for all of the different-state UFG Al *** yield strengths_（YS）,ultimate tensile strengths_（UTS）,and uniform straineexhibited a strong dependence on D when D≤20%;however,when D was in the range from 20%to 50%,no obvious change in mechanical properties was *** micro-mechanism for the effect of cyclic pre-deformation on the tensile properties of the ECAPed UFG Al was revealed and compared with that of ECAPed UFG Cu through the observations of deformation features and microstructures.

关键词： ultrafine-grained aluminum cyclic pre-deformation tensile property microstructure deformation mechanism

High-temperature fatigue behavior of 15CrNbTi ferritic stainless steel

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Journal of Iron and Steel Research International 2019年第3期26卷 285-291页

作者： Tian-long liu li-jia chen Hong-yun Bi Xin Che School of Materials Science and Engineering Shenyang University of Tech no logy Shenyang 110870 Liaoning. China Baosteel Central Research Institute Baosteel Co..Ltd.Shanghai 201900China

In order to investigate the high-temperature fatigue and fatigue-creep behavior of 15CrNbTi ferritic stainless steel at 800°C,fatigue tests without holding time in laboratory air and with 10 s holding time induced at maximum cyclic stress under argon atmosphere were conducted on an electrohydraulic servo fatigue testing *** addition,the morphologies of fatigue fracture surfaces were observed,and the precipitates and dislocation substructures were *** experimental results show that the fatigue limit of 15CrNbTi ferritic stainless steel is 30 MPa at 800°*** fatigue life of the experimental steel obviously decreases if holding time of 10 s is introduced at maximum cyclic *** two test conditions,the fatigue cracks transgranularly initiate at the free surface of fatigue specimens and then propagate in a transgranular *** is dem on strated that three kinds of precipitates inclu ding(Nb,Ti)C phase,Fe2Nb phase and Fe3Nb3C phase can be observed in 15CrNbTi ferritic stainless steel,and the Fe2Nb and Fe3Nb3C phases are mainly precipitated during the fatigue *** the fatigue deformation area,both dislocation tangles and dislocation arrays are ***,the sub-grains which form during the cycling deformation with holding time of 10 s are also ***,the formation of sub-grains leads to the deterioration of the fatigue life of 15CrNbTi steel.

关键词： Ferritic stainless steel-High-temperature fatigue Holding time Fatigue fracture Precipitate Dislocation substructure

Spatial electron-spin splitting in single-layered semiconductor microstructure modulated by Dresselhaus spin-orbit coupling

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Chinese Physics B 2024年第11期33卷 457-461页

作者： jia-li chen Sai-Yan chen li Wen Xue-li Cao Mao-Wang Lu College of Physics and Electronic Information Engineering Guilin University of TechnologyGuilin 541004China

Combining theory and computation,we explore the Goos–H¨anchen(GH)effect for electrons in a single-layered semiconductor microstructure(SLSM)modulated by Dresselhaus spin–orbit coupling(SOC).GH displacement depends on electron spins thanks to Dresselhaus SOC,therefore electron spins can be separated from the space domain and spinpolarized electrons in semiconductors can be *** the magnitude and sign of the spin polarization ratio change with the electron energy,in-plane wave vector,strain engineering and semiconductor layer *** spin polarization ratio approaches a maximum at resonance;however,no electron-spin polarization occurs in the SLSM for a zero in-plane wave *** importantly,the spin polarization ratio can be manipulated by strain engineering or semiconductor layer thickness,giving rise to a controllable spatial electron-spin splitter in the field of semiconductor spintronics.

关键词： semiconductor spintronics single-layered semiconductor microstructure(SLSM) spin-orbit coupling(SOC) Goos-Hänchen(GH)effect electron-spin polarization

Microstructure and wear behaviors of TiB/TiC reinforced Ti2Ni/α(Ti) matrix coating produced by laser cladding

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Rare Metals 2020年第3期39卷 304-315页

作者： Jin-Zhong Shao Jun li Rui Song Lv-lin Bai jia-li chen Cui-Cui Qu School of Materials Engineering Shanghai University of Engineering ScienceShanghai201620China

A Ti2Ni/a(Ti)matrix composite coating reinforced by TiC and TiB was prepared on a Ti6A14V substrate by laser *** microstructure of the coating was examined and *** wear behavior of the coating at various sliding speeds was investigated from the perspective of energy dissipation,and the relationship between accumulated dissipated energy(ΣE)and accumulated wear volume(ΣV)was *** indicate a good linear relationship betweenΣE andΣV at low sliding speed(0.1 m·s-1);at higher sliding speed(0.2 m·s-1),the relationship between these parameters follows a quadratic *** results may be explained from the perspective of energy transformation,wherein the friction heat and plastic deformation of the coating surface consume a substantial amount ofΣE at high sliding speed(0.2 m·s-1)and the remainder of the energy is used to produce worn coating *** wear mechanism of the coating involves a combination of microcutting and brittle debonding accompanied by oxidization of the worn surface and formation of Al2O3 adherents.

关键词： Wear behaviors Coating Laser cladding Accumulated dissipated energy

A numerical method to calculate dwell time for electron in semiconductor nanostructure

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Communications in Theoretical Physics 2023年第1期75卷 162-166页

作者： Shi-Shi Xie Mao-Wang Lu Sai-Yan chen Ying-Jie Qin li Wen jia-li chen College of Science Guilin University of TechnologyGuilin 541004China

To some extent,the operational quickness of semiconductor devices depends on the transmission time of an electron through semiconductor ***,the calculation of transmission time is very difficult,thanks to both the contentious definition of the transmission time in quantum mechanics and the complicated effective potential functions experienced by electrons in semiconductor ***,based on an improved transfer matrix method to numerically solve the Schr?dinger equation and H G Winful’s relationship to calculate the dwell time,we develop a numerical approach to evaluate the transmission time of an electron in semiconductor *** to the exactly resolvable case of the rectangular potential barrier,the established numerical approach possesses high precision and small error,which may be employed to explore the dynamic response and operating speed of semiconductor *** proposed numerical method is successfully applied to the calculation of dwell time for an electron in double rectangular potential barriers and the dependence of transmission time on the number of potential barriers is revealed.

关键词： semiconductor device quantum tunneling effect dwell time improved transfer matrix method H G Winful’s(HGW)relationship