A new kind of group coordination control problemgroup hybrid coordination control is investigated in this paper.The group hybrid coordination control means that in a whole multi-agent system(MAS)that consists of two s...A new kind of group coordination control problemgroup hybrid coordination control is investigated in this paper.The group hybrid coordination control means that in a whole multi-agent system(MAS)that consists of two subgroups with communications between them,agents in the two subgroups achieve consensus and containment,respectively.For MASs with both time-delays and additive noises,two group control protocols are proposed to solve this problem for the containment-oriented case and consensus-oriented case,respectively.By developing a new analysis idea,some sufficient conditions and necessary conditions related to the communication intensity betw een the two subgroups are obtained for the following two types of group hybrid coordination behavior:1)Agents in one subgroup and in another subgroup achieve weak consensus and containment,respectively;2)Agents in one subgroup and in another subgroup achieve strong consensus and containment,respectively.It is revealed that the decay of the communication impact betw een the two subgroups is necessary for the consensus-oriented case.Finally,the validity of the group control results is verified by several simulation examples.展开更多
The contradiction between manufacturing accuracy and manufacturing efficiency is discussed in this paper.In order to solve this problem,a novel droplet-targeting laser hybrid indirect arc for additive manufacturing te...The contradiction between manufacturing accuracy and manufacturing efficiency is discussed in this paper.In order to solve this problem,a novel droplet-targeting laser hybrid indirect arc for additive manufacturing technology is proposed in which a couple of wires are melted using the alternating current with interwire indirect arc to achieve high deposition rate.On the other hand,droplets actively target the laser beam and detach from wire tip under the recoil pressure subjected to pulsed laser irradiating at desired position and with controlled mass for a precise bead forming.The process of alternative droplet growing at desired position are mathematically analyzed and then preliminary verified by experiment.By precisely controlling the wire feed speed and current frequency,the melting process at desired position and mass of wire is successfully obtained which is the fundamental for next-step for the droplet actively targeting laser.展开更多
Metal additive manufacturing technology has been widely used in prototyping,parts manufacturing and repairing.Metal additive manufacturing is a multi-scale and multi-physical coupling process with complex physical phe...Metal additive manufacturing technology has been widely used in prototyping,parts manufacturing and repairing.Metal additive manufacturing is a multi-scale and multi-physical coupling process with complex physical phenomena of heat and mass transfer and microstructure evolution.It is hard to directly observe the dynamic behavior and microstructure evolution of molten pool during additive manufacturing.Therefore,numerical simulation of additive manufacturing process is significant since it can efficiently and pertinently predict and analyze the physical phenomena in the process of metal additive manufacturing,and provide a reference for technological parameters selection.In this review,the research progress of numerical simulation of metal additive manufacturing is discussed.Various aspects of numerical simulation models are reviewed,including:(1)Introduction of basic control method and physical description of numerical simulation models;(2)Comparison of various heat and mass transfer models based on different physical assumptions(heat conduction model;heat flux coupling model;discrete powder particle heat flux coupling model);(3)Applications of various microstructure evolution models[phase field(PF),cellular automata(CA),and Monte Carlo(MC)].Finally,the development trend of numerical simulation of metal additive manufacturing,including the thermal-flow-solid coupling model and deep learning for numerical model,is analyzed.展开更多
在分析正宁煤煤质特性的基础上,考察了添加剂用量、粒度级配等对其制备水煤浆的影响。试验结果表明：当添加剂用量为0.8%,细煤粉比例为60%-70%时,所制备的水煤浆的质量分数为64.3%,此时水煤浆粘度为1 000 m Pa·s,符合工业水煤浆制...在分析正宁煤煤质特性的基础上,考察了添加剂用量、粒度级配等对其制备水煤浆的影响。试验结果表明：当添加剂用量为0.8%,细煤粉比例为60%-70%时,所制备的水煤浆的质量分数为64.3%,此时水煤浆粘度为1 000 m Pa·s,符合工业水煤浆制备标准。配煤试验表明,该煤与环县煤的配比为3∶7时,所制煤浆的质量分数达到68%,较正宁煤单独制浆提高了近4个百分点,所制备的水煤浆72 h的析水率为10.2%。展开更多
基金supported by the National Natural Science Foundation of China(62073305)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(CUG170610)。
文摘A new kind of group coordination control problemgroup hybrid coordination control is investigated in this paper.The group hybrid coordination control means that in a whole multi-agent system(MAS)that consists of two subgroups with communications between them,agents in the two subgroups achieve consensus and containment,respectively.For MASs with both time-delays and additive noises,two group control protocols are proposed to solve this problem for the containment-oriented case and consensus-oriented case,respectively.By developing a new analysis idea,some sufficient conditions and necessary conditions related to the communication intensity betw een the two subgroups are obtained for the following two types of group hybrid coordination behavior:1)Agents in one subgroup and in another subgroup achieve weak consensus and containment,respectively;2)Agents in one subgroup and in another subgroup achieve strong consensus and containment,respectively.It is revealed that the decay of the communication impact betw een the two subgroups is necessary for the consensus-oriented case.Finally,the validity of the group control results is verified by several simulation examples.
基金supported by National Natural Science Foundation of China(51475009)National Natural Science Funded Youth Projects(51505009)+1 种基金Natural Science Foundation of Beijing Projects(3162004)China Postdoctoral Science Foundation Program(2015M570021)。
文摘The contradiction between manufacturing accuracy and manufacturing efficiency is discussed in this paper.In order to solve this problem,a novel droplet-targeting laser hybrid indirect arc for additive manufacturing technology is proposed in which a couple of wires are melted using the alternating current with interwire indirect arc to achieve high deposition rate.On the other hand,droplets actively target the laser beam and detach from wire tip under the recoil pressure subjected to pulsed laser irradiating at desired position and with controlled mass for a precise bead forming.The process of alternative droplet growing at desired position are mathematically analyzed and then preliminary verified by experiment.By precisely controlling the wire feed speed and current frequency,the melting process at desired position and mass of wire is successfully obtained which is the fundamental for next-step for the droplet actively targeting laser.
基金the National Key R&D Program of China(No.2017YFE0123500 and No.2017YFB1103701)。
文摘Metal additive manufacturing technology has been widely used in prototyping,parts manufacturing and repairing.Metal additive manufacturing is a multi-scale and multi-physical coupling process with complex physical phenomena of heat and mass transfer and microstructure evolution.It is hard to directly observe the dynamic behavior and microstructure evolution of molten pool during additive manufacturing.Therefore,numerical simulation of additive manufacturing process is significant since it can efficiently and pertinently predict and analyze the physical phenomena in the process of metal additive manufacturing,and provide a reference for technological parameters selection.In this review,the research progress of numerical simulation of metal additive manufacturing is discussed.Various aspects of numerical simulation models are reviewed,including:(1)Introduction of basic control method and physical description of numerical simulation models;(2)Comparison of various heat and mass transfer models based on different physical assumptions(heat conduction model;heat flux coupling model;discrete powder particle heat flux coupling model);(3)Applications of various microstructure evolution models[phase field(PF),cellular automata(CA),and Monte Carlo(MC)].Finally,the development trend of numerical simulation of metal additive manufacturing,including the thermal-flow-solid coupling model and deep learning for numerical model,is analyzed.
文摘在分析正宁煤煤质特性的基础上,考察了添加剂用量、粒度级配等对其制备水煤浆的影响。试验结果表明：当添加剂用量为0.8%,细煤粉比例为60%-70%时,所制备的水煤浆的质量分数为64.3%,此时水煤浆粘度为1 000 m Pa·s,符合工业水煤浆制备标准。配煤试验表明,该煤与环县煤的配比为3∶7时,所制煤浆的质量分数达到68%,较正宁煤单独制浆提高了近4个百分点,所制备的水煤浆72 h的析水率为10.2%。
