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Journal of Bionic Engineering 2014年第4期11卷 610-619页

作者： Zhongji Cheng Jianshe lian Yanxian Hui guangyu li Key Laboratory of Automobile Materials (Ministry of Education of China) College of Materials Science and Engineering Jilin University Changchun 130022 P. R. China

Bioactive calcium phosphate coatings were prepared on AZ91D magnesium alloy in phosphating solution in order to im- prove the corrosion resistance of the magnesium alloy in Simulated Body Fluid （SBF）. The surface morphologies and compo- sitions of the calcium phosphate coatings deposited in the phosphating bath with different compositions were investigated by Scanning Electron Microscopy （SEM） with Energy Dispersive Spectrometer （EDS） and X-ray Diffraction （XRD）. Results showed that the calcium phosphate coating was mainly composed of dicalcium phosphate dihydrate （CaHPO4o2H20, DCPD）, with Ca/P ratio of approximately 1 ： 1. The corrosion resistance was evaluated by acid drop, electrochemical polarization, elec- trochemical impedance spectroscopy and immersion tests. The dense and uniform calcium phosphate coating obtained from the optimal phosphating bath can greatly decrease the corrosion rate and hydrogen evolution rate of AZ91D magnesium alloy in SBE

关键词： DCPD coating chemical deposited method magnesium alloy corrosion rate SBF

Alignment efficient image-sentence retrieval considering transferable cross-modal representation learning

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Frontiers of Computer Science 2024年第1期18卷 77-91页

作者： Yang YANG Jinyi GUO guangyu li Lanyu li Wenjie li Jian YANG School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Department of Computing Hong Kong Polytechnic UniversityHong Kong 100872China State Key Lab.for Novel Software Technology Nanjing UniversityNanjing 210094China 14th Research Institute of China Electronics Technology Group Corporation Nanjing 210094China guangyu.li2017@***

Traditional image-sentence cross-modal retrieval methods usually aim to learn consistent representations of heterogeneous modalities,thereby to search similar instances in one modality according to the query from another modality in *** basic assumption behind these methods is that parallel multi-modal data(i.e.,different modalities of the same example are aligned)can be obtained in *** other words,the image-sentence cross-modal retrieval task is a supervised task with the alignments as ***,in many real-world applications,it is difficult to realign a large amount of parallel data for new scenarios due to the substantial labor costs,leading the non-parallel multi-modal data and existing methods cannot be used *** the other hand,there actually exists auxiliary parallel multi-modal data with similar semantics,which can assist the non-parallel data to learn the consistent ***,in this paper,we aim at“Alignment Efficient Image-Sentence Retrieval”(AEIR),which recurs to the auxiliary parallel image-sentence data as the source domain data,and takes the non-parallel data as the target domain *** single-modal transfer learning,AEIR learns consistent image-sentence cross-modal representations of target domain by transferring the alignments of existing parallel ***,AEIR learns the image-sentence consistent representations in source domain with parallel data,while transferring the alignment knowledge across domains by jointly optimizing a novel designed cross-domain cross-modal metric learning based constraint with intra-modal domain adversarial ***,we can effectively learn the consistent representations for target domain considering both the structure and semantic ***,extensive experiments on different transfer scenarios validate that AEIR can achieve better retrieval results comparing with the baselines.

关键词： image-sentence retrieval transfer learning semantic transfer structure transfer

An improved constant volume cycle model for performance analysis and shape design of PDRE nozzle

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Applied Mathematics and Mechanics(English Edition) 2018年第2期39卷 193-206页

作者： guangyu li Xiaowei li Jue DING Peifen WENG Zhanbin LU Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

An improved constant volume cycle （CVC） model is developed to analyze the nozzle effects on the thrust and specific impulse of pulse detonation rocket engine （PDRE）. Theoretically, this model shows that the thrust coefficient/specific impulse of PDRE is a function of the nozzle contraction/expansion ratio and the operating frequency. The relationship between the nozzle contraction ratio and the operation frequency is obtained by introducing the duty ratio, by which the key problem in the theoretical design can be solved. Therefore, the performance of PDRE can be accessed to guide the preliminary shape design of nozzle conveniently and quickly. The higher the operating frequency of PDRE is, the smaller the nozzle contraction ratio should be. Besides, the lower the ambient pressure is, the larger the expansion ratio of the nozzle should be. When the ambient pressure is 1.013 × 105 Pa, the optimal expansion ratio will be less than 2.26. When the ambient pressure is reduced to vacuum, the extremum of the optimal thrust coefficient is 2.236 9, and the extremum of the specific impulse is 321.01 s. The results of the improved model are verified by numerical simulation.

关键词： pulse detonation rocket engine (PDRE) nozzle specific impulse thrust,constant volume cycle (CVC) model

Generation of high-quality electron beams by ionization injection in a single acceleration stage

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High Power Laser Science and Engineering 2016年第3期4卷 39-45页

作者： Nasr A.M.Hafz Song li guangyu li Mohammad Mirzaie Ming Zeng Jie Zhang Key Laboratory for Laser Plasmas(MOE) and Department of Physics and Astronomy Collaborative Innovation Center of IFSAShanghai Jiao Tong University

Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electron beams with large and continuous energy spreads, severely limiting their future applications. Complex target designs based on separating the electron trapping and acceleration stages were proposed as the only way for getting small energy-spread electron beams. Here, based on the self-truncated ionization-injection concept which requires the use of unmatched laser–plasma parameters and by using tens of TW laser pulses focused onto a gas jet of helium mixed with low concentrations of nitrogen, we demonstrate single-stage laser wakefield acceleration of multi-hundred MeV electron bunches with energy spreads of a few percent. The experimental results are verified by PIC simulations.

关键词： ionization injection laser–plasma acceleration PIC simulations self-truncation wakefield

Enhanced mechanical properties of 6082 aluminum alloy via SiC addition combined with squeeze casting

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Journal of Materials Science & Technology 2021年第29期88卷 119-131页

作者： Wenming Jiang Junwen Zhu guangyu li Feng Guan Yang Yu Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China State Key Laboratory of High Performance Complex Manufacturing Central South University410083 ChangshaChina

In order to improve mechanical properties of 6082 aluminum alloy,the SiC_(p)/Al 6082 composites were prepared by the addition of the micron-sized SiC_(p)articles combined with the squeeze *** effects of the SiC_(p)content and squeeze casting on the microstructure and mechanical properties of the 6082 aluminum alloy were investigated by SEM,EDS,TEM,tensile testing and hardness testing analysis *** results exhibited that the SiC_(p)content and squeeze casting had a significant impact on the microstructure and mechanical properties of the 6082 aluminum *** addition of the SiC_(p)refined the grain size of the 6082 aluminum alloy while caused the increase of the porosity with increasing the SiC_(p)content,especially in the permanent mold casting *** to the permanent mold casting,the squeeze casting obviously reduced pore defects,refined grain size and made the SiC_(p)distribute evenly as well as bond tightly with the Al *** tensile strength,yield strength,elongation,elastic modulus and hardness of the 6082 aluminum alloy obtained with the SiC_(p)and squeeze casting were remarkably improved,and the optimal mechanical properties were obtained with a 2 wt.%SiC_(p),and they increased 10.73%,72.7%,193.9%,23.5%and 25.2%,respectively,compared to those of the6082 aluminum alloy obtained without SiC_(p)and squeeze *** fracture surface of the SiC_(p)/Al 6082 composites obtained with the squeeze casting was dense and exhibited a ductile fracture mode.

关键词： 6082 aluminum alloy SiC_(p) Aluminum matrix composites Squeeze casting Microstructure Mechanical properties

Ca-P Conversion Coating on AZ60 Magnesium Alloy for Biomedical Application

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Chemical Research in Chinese Universities 2014年第4期30卷 543-548页

作者： CHENG Zhongji liAN Jianshe HU Xiaoli YANG Xiaohong li guangyu Key Laboratory of Automobile Materials Ministry of Education College of Materials Science and Engineering Jilin University Changchun 130022 P. R. China

To improve the anti-corrosion behaviors of magnesium alloy in the inner environment of human body,a bioactive Ca-P coating was deposited on the AZ60 magnesium alloy by a novel simple *** morphologies of the Ca-P coatings formed under different treatment time were studied by scanning electron microscopy（SEM）.The corrosion behaviors of Ca-P coating were investigated by electrochemical polarization test and electrochemical impedance spectroscopy in both 3％（mass fraction） NaCl solution and simulated body fluid（SBF）.Immersion test in SBF was performed to evaluate the corrosion rate of Ca-P coated magnesium alloy.X-Ray diffraction（XRD） analysis result shows that the coating mentioned above mainly consists of dicalcium phosphate dehydrate（CaHPO4·2H2O,DCPD） and β-tricalcium phosphate dehydrate[β-TCP,Ca3（PO4）2],which exhibits good corrosion *** magnesium alloy was immersed in 1 mol/L NaOH solution at 80 ℃ for 2 h,hydroxyapatite [Ca10（PO4）6（OH）2,HA]appeared on the magnesium alloy substrate,which can further decrease the corrosion rate of AZ60 magnesium alloy in SBF.

关键词： Ca-P coating Deposited method Magnesium alloy Corrosion rate Simulated body fluid(SBF)

Improving mechanical properties of AZ91D magnesium/A356 aluminum bimetal prepared by compound casting via a high velocity oxygen fuel sprayed Ni coating

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Journal of Magnesium and Alloys 2022年第4期10卷 1075-1085页

作者： guangyu li Wenming Jiang Feng Guan Junwen Zhu Yang Yu Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound *** effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first *** demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 *** 10μm’s Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds(IMCs)at the interface zone of the AZ91D/A356 bimetal,while the Ni coating with the thickness of 45μm and 190μm can avoid the formation of the Al-Mg *** the Ni coating was 45μm,the Ni coating disappeared and transformed into Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles at the interface *** a thickness of 190μm’s Ni coating,part of the Ni coating remained and the interface layer was composed of the Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles,Mg_(2)Ni layer,Ni solid solution(SS)layer,Al_(3)Ni_(2) layer,Al_(3)Ni layer and sporadic Al_(3)Ni+Al-Al_(3)Ni eutectic structures from AZ91D side to A356 side in *** interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg *** shear strength of the AZ91D/A356 bimetal with a Ni coating of 45μm thickness enhanced 41.4%in comparison with that of the bimetal without Ni coating,and the fracture of the bimetal with 45μm’s Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.

关键词： Magnesium/aluminum bimetal Microstructure Mechanical properties Ni coating Compound casting High velocity oxygen fuel spraying

In Vivo Corrosion Resistance of Ca-P Coating on AZ60 Magnesium Alloy

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Journal of Bionic Engineering 2013年第2期10卷 156-161页

作者： Xing Xiao Haiying Yu Qingsan Zhu guangyu li Yang Qu Rui Gu First Hospital of Jilin University Changchun 130021 P. R. China Shandong Qianfoshan Hospital Jinan 250014 P. R. China Shandong Tumour Hospital Jinan 250117 P. R. China College of Materials Science and Engineering Jilin University Changchun 130022 P. R. China China Japan Union Hospital of Jilin University Changchun 130033 P. R. China

Magnesium-based alloys are frequently reported as potential biodegradable orthopedic implant materials. Controlling the degradation rate and mechanical integrity of magnesium alloys in the physiological environment is the key to their applications. In this study, calcium phosphate （Ca-P） coating was prepared on AZ60 magnesium alloy using phosphating technology. AZ60 samples were immersed in a phosphating solution at 37 ± 2 ℃ for 30 min, and the solution pH was adjusted to 2.6 to 2.8 by adding NaOH solution. Then, the samples were dried in an attemperator at 60 ℃. The degradation behavior was studied in vivo using Ca-P coated and uncoated magnesium alloys. Samples of these two different materials were implanted into rabbit femora, and the corrosion resistances were evaluated after 1, 2, and 3 months. The Ca-P coated samples corroded slower than the uncoated samples with prolonged time. Significant differences （p 〈 0.05） in mass losses and corrosion rates between uncoated samples and Ca-P coated samples were observed by micro-computed tomography. The results indicate that the Ca-P coating could slow down the degradation of magnesium alloy in vivo.

关键词： Ca-P coating mass loss micro-computed tomography corrosion resistance magnesium alloy

Microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91D bimetallic composites prepared by a compound casting

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Journal of Magnesium and Alloys 2024年第5期12卷 1944-1964页

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91D bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91D bimetallic composites had a metallurgical reaction layer(MRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91D composites,while the hypereutectic Al-Si/AZ91D composites were *** MRL included eutectic layer(E layer),intermetallic compound layer(IMC layer)and transition region layer(T layer).In the IMC layer,the hypereutectic Al-Si/AZ91D composites contained some Si solid solution and flocculent Mg_(2)Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91D ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91D bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91D composite obtained a maximum shear strength of 58.6 MPa,which was 73.4% higher than the Al-6Si/AZ91D *** fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the Mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-Mg IMCs as well as the orientation change of the MRL.

关键词： Al/Mg bimetallic composites Si content Mg_(2)Si reinforcement Microstructure Mechanical properties Fracture behavior

Losses of Ecosystem Service Values in the Taihu Lake Basin from 1979 to 2010

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Frontiers of Earth Science 2017年第2期11卷 310-320页

作者： Hui ZHANG Qiao WANG guangyu li Hanpei ZHANG Jue ZHANG College of Geographical Sciences Nanjing Normal University Nanjing 210023 China Nanjing Institute of Environmental Science Ministry of Environmental Protection Nanjing 210042 China Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET) Nanjing University of Information Science & Technology Nanjing 210044 China Environmental Satellite Application Center Ministry of Environmental Protection Beijing 100029 China

The Taihu Lake Basin, an east-coastal developed area, is one of the fastest-growing metropolitan areas in China. Ecosystem services in the Taihu Lake Basin have been overexploited and jeopardized. Based on land-use and land-cover change （LUCC） data from 1979, 1984, 2000, and 2010, in conjunction with the adjusted ecosystem service values （ESV）, changes in ESV were analyzed in detail. Results revealed that LUCC resulted in a substantial decrease in total ESV from S3.92 billion in 1979 to S2.98 billion in 2010. The ESV of cropland decreased from $1.64 billion in 1979 to S1.34 billion in 2010, which represented a 20.28% reduction. The ESV of water areas decreased from S1.08 billion in 1979 to $0.36 billion in 2010, which represented a 65.62% reduction mainly because of a decline in water quality. In terms of annual change rate, cropland and water areas showed a sustained downward trend. Spatially, ESV declines were mainly observed in Suzhou, Wuxi, Changzhou, and Shanghai, probably due to a combination of economic progress, population growth, and rapid urbanization. The research results can be a useful reference for policymakers in mitigating ESV decline.

关键词： ecosystem service values land use/land cover,water quality Taihu Lake Basin