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Study of Cracking Mechanism and Wear Resistance in Laser Cladding Coating of Ni-based Alloy

Chinese Journal of Mechanical engineering 2021年第5期34卷 259-272页

作者： Zhenglei Yu Lunxiang Li Deqiang Zhang Guangfeng Shi Guang Yang Zezhou Xu Zhihui Zhang Key Lab of Bionic Engineering Ministry of EducationJilin UniversityChangchun 130022China State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130022China College of Mechanical and Electric Engineering Changchun University of Science and TechnologyChangchun 130022China College of Mechanical Engineering and Automation Liaoning University of TechnologyJinzhou 121001China Key Laboratory of Fundamental Science for National Defense of Aeronautical Digital Manufacturing Process Shenyang Aerospace UniversityShenyang 110136China

Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding,but the crack sensitivity would be increase due to the higher strength and hardness,which reduced the wear resistance of Ni-based *** this paper,Ni-based coatings with the addition of a plastic phase(an austenitic stainless net)were prepared using laser cladding technology,and the CeO_(2)was added in cladding *** cracking mechanism,microhardness,microstructure,phase composition,and wear properties were *** relationship between thermal stress and the elastic and plastic fracture had been developed from the standpoint of fracture mechan-ics and thermal elastic fracture *** fracture criterion of the nickel-based coating was obtained,and the study has shown that the crack sensitivity could be reduced by decreasing the thermal expansion coefficientΔα.Thus,a new method was proposed,which the stainless steel nets were prefabricated on the *** was found that the number of cracks reduced significantly with the addition of stainless steel *** the stainless steel net with 14 mesh was added in Ni-based coatings,the average microhardness of nickel composite coating was 565 HV_(0.2),which was 2.6 times higher than that of the 45 steel *** the rare earth oxide 4 wt.%CeO_(2)and stainless steel net were added in the Ni-based coating reducing the microhardness(the average microhardness is 425 HV_(0.2)),the wear resistance of it improved *** wear volume of Ni-based composite coating was 0.56×10^(−5) mm^(3)·N^(−1)·m^(−1),which was 85.1%lower than that of 45 *** experiment results have shown that the Nickel-based composite coating is equipped with low crack sensitivity and high abrasive resistance with austenitic stainless net and the rare earth oxide 4 wt.%*** research offers an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated

关键词： Laser cladding Wear resistance Crack sensitivity Stainless steel net Rare earth oxide

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Breakdown of Raman selection rules by Frohlich interaction in few-layer WS_(2)

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Nano Research 2021年第1期14卷 239-244页

作者： Qing-Hai Tan Yu-Jia Sun Xue-Lu Liu Kai-Xuan Xu Yuan-Fei Gao Shu-Liang Ren Ping-Heng Tan Jun Zhang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsCenter of Materials Science and Optoelectronics EngineeringCAS Center of Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing 100083China Beijing Academy of Quantum Information Science Beijing 100193China

The polarization selection rule of Raman scattering is crucial in symmetry analysis of elementary excitations in semiconductors and correlated electron *** we reported the observation of breakdown of Raman selection rules in few-layer WS_(2) by using resonant Raman *** the excitation energy is close to the dark A exciton state,we observed some infrared active modes and backscattering forbidden ***,we found that all observed phonon modes follow the same paralleled-polarization *** to the electron-phonon coupling near the band edge in WS_(2),we proposed a theoretical model based on the intraband Frohlich *** this case,the polarization response of the scattering signal is no longer determined by the original Raman tensor of scattered ***,it is determined by a new isotropic Raman tensor that generated from this intraband Frohlich interaction between dark A exciton and *** found that this theoretical model is in excellent agreement with the observed *** breakdown of Raman selection rules can violate the conventional limitations of the optical response and provide an effective method to control the polarization of Raman scattering signals in two-dimensional materials.

关键词： WS_(2) resonant Raman scattering dark exciton Raman section rules Frohlich interaction

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How to Find a Large Solution Set to Cover the Entire Pareto Front in Evolutionary Multi-Objective Optimization

How to Find a Large Solution Set to Cover the Entire Pareto ...

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IEEE International Conference on Systems, Man and Cybernetics

作者： Lie Meng Pang Yang Nan Hisao Ishibuchi Department of Computer Science and Engineering Guangdong Provincial Key Laboratory of Brain-inspired Intelligent Computation Southern University of Science and Technology Shenzhen China

Recently, it has been pointed out in many studies that the performance of evolutionary multi-objective optimization (EMO) algorithms can be improved by selecting solutions from all examined solutions stored in an unbounded external archive. This is because in general the final population is not the best subset of the examined solutions. To obtain a good final solution set in such a solution selection framework, subset selection from a large candidate set (i.e., all examined solutions) has been studied. However, since good subsets cannot be obtained from poor candidate sets, a more important issue is how to find a good candidate set, which is the focus of this paper. In this paper, we first visually demonstrate that the entire Pareto front is not covered by the examined solutions through computational experiments using MOEA/D, NSGA-III and SMS-EMOA on DTLZ test problems. That is, the examined solution set stored in the unbounded archive has some large holes (i.e., some uncovered area of the Pareto front). Next, to evaluate the quality of the examined solution set (i.e., to measure the size of the largest hole), we propose the use of a variant of the inverted generational distance (IGD) indicator. Then, we propose a simple modification of EMO algorithms to improve the quality of the examined solution set. Finally, we demonstrate the effectiveness of the proposed modification through computational experiments.

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Improved Ductility by Reducing Powder Size in Laser Powder Bed Fusion of AlSi10Mg

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Additive Manufacturing Frontiers 2024年第1期3卷 160-172页

作者： Fuzhong Chu Haopeng Shen Jianwen Li Juan Hou Kai Zhang Zongyan Zhou Yuman Zhu Xinhua Wu Aijun Huang ARC Research Hub for Computational Particle Technology Department of Chemical and Biological EngineeringMonash UniversityClaytonVIC 3800Australia Monash Centre for Additive Manufacturing Monash UniversityNotting HillVIC 3168Australia Department of Materials Science and Engineering Monash UniversityClaytonVIC 3800Australia School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai200093China Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and TechnologyNanchang330013China

Strict control of powder properties,especially particle size distribution(PSD),is critical in the laser powder bed fusion(LPBF)process to ensure the quality of the fabricated *** work shows that reducing the powder size could improve the ductility of LPBF fabricated *** tensile elongation increased from 4.1%to 8.8%when AlSi10Mg powder sizes(D50 value)decreased from 76μm to 16μm in the as-fabricated *** results showed that fine powder size stimulates epitaxial grain growth due to excessive *** presence of epitaxial columnar grains makes the crack path across inner melt pools more frequent and travels from the coarse melt pool zones to the fine melt pool *** work suggests that powder size is a crucial factor to be considered in maintaining repeatable mechanical properties in LPBF processes,particularly when ductility and ductility-dominated properties are critical.

关键词： Particle size distribution Laser powder bed fusion Ductility Epitaxial columnar grain

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Two-Stage Lazy Greedy Inclusion Hypervolume Subset Selection for Large-Scale Problem

Two-Stage Lazy Greedy Inclusion Hypervolume Subset Selection...

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IEEE International Conference on Systems, Man and Cybernetics

作者： Yang Nan Tianye Shu Hisao Ishibuchi Department of Computer Science and Engineering Guangdong Provincial Key Laboratory of Brain-inspired Intelligent Computation Southern University of Science and Technology Shenzhen China

Hypervolume subset selection (HSS) is a hot topic in the evolutionary multi-objective optimization (EMO) community since hypervolume is the most widely-used performance indicator. In the literature, most HSS algorithms were designed for small-scale HSS (e.g., environmental selection: select $N$ solutions from $2N$ solutions where $N$ is the population size). Few researchers focus on large-scale HSS as a post-processing procedure in an unbounded external archive framework (i.e., subset selection from all examined solutions). In this paper, we propose a two-stage lazy greedy inclusion HSS (TGI-HSS) algorithm for large-scale HSS. In the first stage of TGI- HSS, a small solution set is selected from a large-scale candidate set using an efficient subset selection method (which is not based on exact hypervolume calculation). In the second stage, the final subset is selected from the small solution set using an existing efficient HSS algorithm. Experimental results show that the computational time can be significantly reduced by the proposed algorithm in comparison with other state-of-the-art HSS algorithms at the cost of only a small deterioration of the selected subset quality.

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AAV-Assisted Joint Mobile Edge Computing and Data Collection via Matching-Enabled Deep Reinforcement Learning

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IEEE Internet of Things Journal 2025年第12期12卷 19782-19800页

作者： Boxiong Wang Hui Kang Jiahui Li Geng Sun Zemin Sun Jiacheng Wang Dusit Niyato College of Computer Science and Technology Jilin University Changchun China College of Computer Science and Technology and the Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Changchun China College of Computing and Data Science Nanyang Technological University Jurong West Singapore

Autonomous aerial vehicle (AAV)-assisted mobile edge computing (MEC) and data collection (DC) have been popular research issues. Different from existing works that consider MEC and DC scenarios separately, this article investigates a multi-AAV-assisted joint MEC-DC system. Specifically, we formulate a joint optimization problem to minimize the MEC latency and maximize the collected data volume. This problem can be classified as a nonconvex mixed integer programming problem that exhibits long-term optimization and dynamics. Thus, we propose a deep reinforcement learning-based approach that jointly optimizes the AAV movement, user transmit power, and user association in real time to solve the problem efficiently. Specifically, we reformulate the optimization problem into an action space-reduced Markov decision process (MDP) and optimize the user association by using a two-phase matching-based association (TMA) strategy. Subsequently, we propose a soft actor-critic (SAC)-based approach that integrates the proposed TMA strategy (SAC-TMA) to solve the formulated joint optimization problem collaboratively. simulation results demonstrate that the proposed SAC-TMA is able to coordinate the two subsystems and can effectively reduce the system latency and improve the DC volume compared with other benchmark algorithms.

关键词： Internet of Things Optimization Autonomous aerial vehicles Interference Wireless networks Sun Data collection Real-time systems Production facilities Performance evaluation

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Facile One-Step Solvothermal Synthesis of Flower-Like Biobr Microspheres For the Efficient Degradation of Organic Dyes Under Visible Light Irradiation

SSRN

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SSRN 2024年

作者： Hou, Xinru Ma, Yongxiang Zhang, Weijin Zhou, Xiaotong Kang, Ziqian Tian, Hongwei Hu, Xiaoying College of Science Laboratory of Materials Design and Quantum Simulation Changchun University of Science and Technology Changchun130022 China Key Laboratory of Automobile Materials Ministry of Education School of Materials Science and Engineering Jilin University Changchun130012 China Dalian Jiaotong University China Laboratory of Materials Design and Quantum Simulation China

In this study, BiOBr microspheres were successfully synthesized through a facile solvothermal route in the presence of glycerol, and the photocatalysts were characterized using X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. BiOBr-6, which was synthesized using glycerol, exhibited a flower-like morphology with a diameter of ~1000 nm and was composed of two-dimensional flakes with the size of tens of nanometers. The photocatalytic activity of the optimized BiOBr-6 was evaluated through the photocatalytic degradation of rhodamine B, methylene blue, methyl orange, and chrome blue-black R under visible light irradiation. Within 60 min, the degradation rates reached 99.7%, 99.6%, 98.1%, and 98.0%. We concluded that the highly visible-light-driven catalytic performance of the flower-like BiOBr sample was associated with its high surface area, porous structure, and low bandgap energy, as well as unique microsphere morphology. The resulting BiOBr microspheres may serve as promising adsorbents and photocatalysts for the treatment of organic pollutants. © 2024, The Authors. All rights reserved.

关键词： Microspheres

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Ensemble R2-based Hypervolume Contribution Approximation

Ensemble R2-based Hypervolume Contribution Approximation

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IEEE Symposium Series on computational Intelligence (SSCI)

作者： Guotong Wu Tianye Shu Yang Nan Ke Shang Hisao Ishibuchi Department of Computer Science and Engineering Guangdong Provincial Key Laboratory of Brain-inspired Intelligent Computation Southern University of Science and Technology Shenzhen China

The hypervolume-based multi-objective evolutionary algorithms (HV-MOEAs) have proven to be highly effective in solving multi-objective optimization problems. However, the computation time of the hypervolume calculation increases significantly as the number of objectives increases. To address this issue, an R2-based hypervolume contribution approximation (R2-HVC) method was proposed. Nevertheless, the original R2-HVC generates a large number of vectors and computes the HVC only once. In this study, we propose an ensemble method based on the R2-HVC method. By using a small number of vectors for repetitive computation and majority voting, the ensemble method can reduce the probability of making incorrect choices. Experimental results show that the proposed method can improve the approximation accuracy while maintaining a similar computation time to the original R2-HVC method.

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Future climate change decreases multi-pathway but increases respiratory human health risks of PAHs across China

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National science Open 2024年第2期3卷 128-147页

作者： Jiaao Bao Xinghui Xia Ying Zhu Bingxiang Zhao Erxue Gu Yanan Liu Xiao Yun Zhenrui Zhang Nannan Xi Yong Geng Ying Xu Zhifeng Yang Derek C.G.Muir Key Laboratory of Water and Sediment Sciences of Ministry of Education State Key Laboratory of Water Environment SimulationSchool of EnvironmentBeijing Normal UniversityBeijing 100875China State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants School of Environmental Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China College of Urban and Environmental Sciences Laboratory for Earth Surface ProcessesSino-French Institute for Earth System SciencePeking UniversityBeijing 100871China National Climate Center China Meteorological AdministrationBeijing 100081China Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education Institute of Environmental and Ecological EngineeringGuangdong University of TechnologyGuangzhou 510006China Aquatic Contaminants Research Division Environment and Climate Change CanadaBurlington L7S 1A1Canada

Future climate change will affect the environmental fate of hydrophobic organic contaminants(HOCs)and associated human health risks,yet the extent of these effects remains ***,we couple a high-resolution environmental multimedia model with a bioaccumulation model to study the multimedia distribution of 16 priority polycyclic aromatic hydrocarbons(PAHs),a group of HOCs,and assess future PAH-related human health risks under varying climate change scenarios over China at a continental *** removing the effects of PAH emission changes,we find that the total PAH concentrations would decrease in the air,freshwater,sediment,soil,and organisms,while the high-molecular-weight PAH would increase in the air with climate warming from 1.5°C to 4°***,the multi-pathway exposure human health risks predominately influenced by dietary ingestion are expected to decrease by 1.7%–20.5%,while the respiratory risks are projected to rise by 0.2%–5.8%in the ***,the persistently high multi-pathway human health risks underscore the need for reducing future PAH emissions by 69%compared with 2009 levels in *** study demonstrates the urgency of limiting PAH emissions under future climate change for public health and highlights the importance of including the contribution of dietary ingestion in human health risk assessment.

关键词： polycyclic aromatic hydrocarbons future climate change human health risks emission reduction

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Enhanced piezoelectricity in 0.7BiFeO_(3)-0.3BaTiO_(3)lead-free ceramics:Distinct effect of poling engineering

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Journal of Materiomics 2023年第5期9卷 971-979页

作者： Aizhen Song Yu-Cheng Tang Hezhang Li Ning Wang Lei Zhao Jun Pei Bo-Ping Zhang The Beijing Municipal Key Laboratory of New Energy Materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing100083China Department of Precision Instrument Tsinghua UniversityBeijing10084China Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province College of Physics Science and TechnologyHebei UniversityBaoding071002China

BiFeO_(3)-BaTiO_(3) based ceramics are considered to be the most promising lead-free piezoelectric ceramics due to their large piezoelectric response and high Curie *** the piezoelectric response of piezoelectric ceramics just appears after poling engineering,in this work,the domain evolution and microscopic piezoresponse were observed in-situ using piezoresponse force microscopy(PFM)and switching spectroscopy piezoresponse force microscopy(SS-PFM),which can effectively study the local switching characteristics of ferroelectric materials especially at the *** new domain nucleation preferentially forms at the boundary of the relative polarization region and expands laterally with the increase of bias voltage and *** maximum piezoresponse(Rs),remnant piezoresponse(Rrem),maximum displacement(Dmax)and negative displacement(Dneg)at 45 V and 120C reach 122,69,127 pm and 75 pm,*** to the distinct effect of poling engineering in full domain switching,the corresponding d33 at 50 kV/cm and 120C reaches a maximum of 205 pC/N,which is nearly twice as high as that at room *** the evolution of ferroelectric domains in the poling engineering of BiFeO_(3)-BaTiO_(3)ceramics provides an insight into the relationship between domain structure and piezoelectric response,which has implications for other piezoelectric ceramics as well.

关键词： 0.7BiFeO_(3)-0.3BaTiO_(3) Domain evolution Microscopic piezoresponse Poling engineering Piezoelectricity

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