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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 casting.The 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 time.Results demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 bimetal.The 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 IMCs.When 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 zone.With 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 sequence.The 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 IMCs.The 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

Characterization and Trading of Energy Level and Energy Shift Considering Virtual Power Plant

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1784-1789页

作者： Shuai Fan Jucheng Xiao Zuyi li guangyu He Key Laboratory of Control of Power Transmission and Conversion Ministry of EducationShanghai Jiao Tong UniversityShanghai200240China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616USA

The capability of shifting the electricity generation or consumption to proper time of the day,also defined as energy shift(ES),is the key factor to ensure the power balance,especially under high penetration of variable renewable energy(VRE).However,the ES is not characterized and traded as an independent product in current market mechanisms.In this letter,the marginal utility of an ES is assessed and leveraged to characterize the effective ES,while a novel market scheme is proposed considering the trading of both ES and energy level(EL).The proposed scheme can well integrate ES producers such as virtual power plants that cannot be rewarded sufficiently to actively participate in the current market because they are principally labeled as EL consumers.Finally,the novel concept and mechanism are illustrated by a numerical study and verified to outperform the existing price schemes on integrating the ES resources and VRE.

关键词： Energy level energy shift variable renewable energy virtual power plant marginal utility

Aquatic Medicine Knowledge Graph Completion Based on Hybrid Convolution

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Journal of Beijing Institute of Technology 2023年第3期32卷 298-312页

作者： Huining Yang Qishu Song liming Shao Guangyu li Zhetao Sun Hong Yu School of Dalian Ocean University and Key Laboratory of Facilities Fisheries Ministry of Education Dalian 116023China

Aquatic medicine knowledge graph is an effective means to realize intelligent aquaculture.Graph completion technology is key to improving the quality of knowledge graph construction.However,the difficulty of semantic discrimination among similar entities and inconspicuous semantic features result in low accuracy when completing aquatic medicine knowledge graph with complex relationships.In this study,an aquatic medicine knowledge graph completion method(TransH+HConvAM)is proposed.Firstly,TransH is applied to split the vector plane between entities and relations,ameliorating the poor completion effect caused by low semantic resolution of entities.Then,hybrid convolution is introduced to obtain the global interaction of triples based on the complete interaction between head/tail entities and relations,which improves the semantic features of triples and enhances the completion effect of complex relationships in the graph.Experiments are conducted to verify the performance of the proposed method.The MR,MRR and Hit@10 of the TransH+HConvAM are found to be 674,0.339,and 0.361,respectively.This study shows that the model effectively overcomes the poor completion effect of complex relationships and improves the construction quality of the aquatic medicine knowledge graph,providing technical support for intelligent aquaculture.

关键词： aquatic medicine knowledge graph graph completion hybrid convolution global features

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

Effect of La on microstructure,mechanical properties and fracture behavior of Al/Mg bimetallic interface manufactured by compound casting

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Journal of Materials Science & Technology 2022年第10期105卷 214-225页

作者： Zheng Zhang Wenming Jiang Guangyu li Junlong Wang Feng Guan Guoliang Jie Zitian Fan State Key Laboratory of Materials Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

To improve the Al/Mg bimetallic interface,La was added into the Al/Mg bimetallic interface manufactured by a compound casting process.The effect of La addition on the microstructure,mechanical properties and fracture behavior of the Al/Mg bimetallic interface and the formation mechanism of the interface were studied in detail.Al_(11)La_(3),Al_(8)Mn_(4)La,Al_(20)Ti_(2)La,and other rare earth precipitates(RE precipitates)preferentially precipitated at the interface with La addition,while the number of the Al_(11)La_(3)and Al_(8)Mn_(4)La located in eutectic structure area(E area)gradually increased and aggregated in the interface with the increase of the La content.Besides,the matrix structure in different areas of the Al/Mg interface changed in different degrees,and the eutectic structure and primaryγ(Mg_(17)Al_(12))dendrites in the E area were refned,but the intermetallic compounds area(IMC area)had no obvious change.With the addition of the La,the interface was strengthened under the comprehensive effect of refnement strengthening and precipitation strengthening from the E area.When the La content increased to 1.0%,the shear strength of the Al/Mg bimetal reached the maximum of 51.54 MPa,which was 30.95%higher than the group without La addition.However,with the further increase of the La content,the large area aggregation of the Al_(11)La_(3)and Al_(8)Mn_(4)La occurred in the interface,leading to the separation of the matrix structure of the E area and the decrease of the shear strength of the Al/Mg interface.

关键词： Compound casting Al-Mg intermetallic compounds Rare earth La Al/Mg interface Microstructure Mechanical properties

Policy Iteration for Optimal Control of Discrete-Time Time-Varying Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2023年第3期10卷 781-791页

作者： guangyu Zhu Xiaolu li Ranran Sun Yiyuan Yang Peng Zhang Beijing Research Center of Urban Traffic Information Sensing and Service Technologies Key Laboratory of Transport Industry of Big Data Application Technologies for Comprehensive Transport Beijing Jiaotong UniversityBeijing 100044China Transport Planning and Research Institute Ministry of TransportChinaBeijing 100028China

Aimed at infinite horizon optimal control problems of discrete time-varying nonlinear systems,in this paper,a new iterative adaptive dynamic programming algorithm,which is the discrete-time time-varying policy iteration(DTTV)algorithm,is developed.The iterative control law is designed to update the iterative value function which approximates the index function of optimal performance.The admissibility of the iterative control law is analyzed.The results show that the iterative value function is non-increasingly convergent to the Bellman-equation optimal solution.To implement the algorithm,neural networks are employed and a new implementation structure is established,which avoids solving the generalized Bellman equation in each iteration.Finally,the optimal control laws for torsional pendulum and inverted pendulum systems are obtained by using the DTTV policy iteration algorithm,where the mass and pendulum bar length are permitted to be time-varying parameters.The effectiveness of the developed method is illustrated by numerical results and comparisons.

关键词： Adaptive critic designs adaptive dynamic programming approximate dynamic programming optimal control policy iteration time-varying

Effect of vibration on interfacial microstructure and mechanical properties of Mg/Al bimetal prepared by a novel compound casting

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Journal of Magnesium and Alloys 2022年第8期10卷 2296-2309页

作者： Feng Guan Wenming Jiang Guangyu li Junwen Zhu Junlong Wang Guoliang Jie Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

In this work,a vibration was applied in the preparation of the Mg/Al bimetal by a novel compound casting in order to improve the mechanical properties of the Mg/Al bimetal,and the effect of the vibration on the interfacial microstructure and mechanical properties of the Mg/Al bimetal was investigated.The results indicated that the vibration had a significant effect on the interfacial microstructure and mechanical properties of the Mg/Al bimetal,but it did not change the phase compositions of the interface,which was composed of layerⅠ(Al3Mg2+Mg2Si),layerⅡ(Al_(12)Mg_(17)+Mg_(2)Si)and layerⅢ(Al_(12)Mg_(17)/δ-Mg).Without vibration,the Mg_(2)Si phase with a needle-like morphology mainly aggregated in the layerⅡof the interface.After the application of the vibration,the SEM and EBSD analysis results showed that the Mg_(2)Si and Al3Mg2phases in the interface were obviously refined,and the distribution of the Mg_(2)Si became more uniform,due to the strong forced convection of the molten metal resulting from the vibration.The TEM analysis indicated that the interface between the A_(l3)Mg_(2) and Mg_(2)Si phases was non-coherent,suggesting the Mg_(2)Si particles cannot act as a heterogeneous nucleation base during the solidification process of the interface.Compared to the Mg/Al bimetal without vibration,the shear strength of the Mg/Al bimetal with vibration increased by about 50%from 31.7 MPa on average to 47.5 MPa,and the hardness of the layer I of the interface increased,and the hardness of the layerⅢdecreased.The fracture surface transformed from a flat fracture morphology without vibration to an irregular zigzag fracture morphology.

关键词： Mg/Al bimetal Vibration Compound casting Interfacial microstructure Bonding properties

Positioning error compensation of an industrial robot using neural networks and experimental study

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Chinese Journal of Aeronautics 2022年第2期35卷 346-360页

作者： Bo li Wei TIAN Chufan ZHANG Fangfang HUA guangyu CUI Yufei li College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Hebei Hanguang Industry Co. LtdHandan 056017China

Due to the characteristics of high efficiency,wide working range,and high flexibility,industrial robots are being increasingly used in the industries of automotive,machining,electrical and electronic,rubber and plastics,aerospace,food,etc.Whereas the low positioning accuracy,resulted from the serial configuration of industrial robots,has limited their further developments and applications in the field of high requirements for machining accuracy,e.g.,aircraft assembly.In this paper,a neural-network-based approach is proposed to improve the robots’positioning accuracy.Firstly,the neural network,optimized by a genetic particle swarm algorithm,is constructed to model and predict the positioning errors of an industrial robot.Next,the predicted errors are utilized to realize the compensation of the target points at the robot’s workspace.Finally,a series of experiments of the KUKA KR 500–3 industrial robot with no-load and drilling scenarios are implemented to validate the proposed method.The experimental results show that the positioning errors of the robot are reduced from 1.529 mm to 0.344 mm and from 1.879 mm to 0.227 mm for the no-load and drilling conditions,respectively,which means that the position accuracy of the robot is increased by 77.6%and 87.9%for the two experimental conditions,respectively.

关键词： Aircraft assembly Error compensation Industrial robot Neural network Robotic drilling

Cow milkα_(s1)-casein induces allergic responses in a mouse model of atopy

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Food Science and Human Wellness 2022年第5期11卷 1282-1289页

作者： guangyu Wang Xiaofeng Yu Yanjun Cong linfeng li Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients College of Food and HealthBeijing Technology and Business UniversityBeijing 100048China Department of Dermatology Beijing Friendship HospitalBeijing 100050China

α_(s1)-Casein is a potential allergen to induce hypersensitivity in cow milk.We had identifiedα_(s1)-casein and its epitopes in previous studies.The present study aimed to evaluate the allergic mechanism ofα_(s1)-casein in a BALB/c mouse model.The levels of specific IgE,mast cell proteinase,histamine and cytokines in sensitized mice were determined,and the clinical and pathological observation were evaluated.Results showed that the levels of specific IgE,mast cell proteinase,histamine,IL-4,IL-5,IL-10 increased significantly with a dose-dependent trend.The local alveolar septum collapsed or thickened,and lymphatic foci were produced in the spleen and thymus,and the inflammatory cells infiltrated in small intestinal mucosa mesenchyme.In conclusion,the levels of specific IgE,mast cell proteinase,histamine,IL-4,IL-5,IL-10 and some inflammatory factors could possibly serve as allergic biomarkers ofα_(s1)-casein,however,additional studies on signal transduction and gene expression are necessary in future.

关键词： Cow milk α_(s1)-Casein Allergen BALB/c mouse model Allergic mechanism