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Strengthened Initialization of Adaptive Cross-Generation Differential Evolution

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Computer Modeling in Engineering & Sciences 2022年第3期129卷 1495-1516页

作者： Wei Wan Gaige wang junyu Dong Department of Computer Science of Technology Ocean University of ChinaQingdao266100China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin UniversityChangchun130012China Guangxi Key Laboratory of Hybrid Computation and IC Design Analysis Guangxi University for NationalitiesNanning530006China

Adaptive Cross-Generation Differential Evolution(ACGDE)is a recently-introduced algorithm for solving multiobjective problems with remarkable performance compared to other evolutionary algorithms(EAs).However,its convergence and diversity are not satisfactory compared with the latest algorithms.In order to adapt to the current environment,ACGDE requires improvements in many aspects,such as its initialization and mutant operator.In this paper,an enhanced version is proposed,namely SIACGDE.It incorporates a strengthened initialization strategy and optimized parameters in contrast to its predecessor.These improvements make the direction of crossgeneration mutation more clearly and the ability of searching more efficiently.The experiments show that the new algorithm has better diversity and improves convergence to a certain extent.At the same time,SIACGDE outperforms other state-of-the-art algorithms on four metrics of 24 test problems.

关键词： Differential Evolution(DE) multi-objective optimization(MO) opposition-based learning parameter adaptation

Utilizing a metal-forging inspired chain combing strategy to enhance properties and expand applications of Nylon 66 plastic via heat inducing

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Nano Research 2024年第3期17卷 2164-2171页

作者： junyu Yang Jiangwei Zhang Nan wang Guangyuan Zhou Division of Energy Materials Daglian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Innovation Center of Energy Material and Chemistry College of Chemistry and Chemical EngineeringInner Mongolia UniversityHohhot 010021China

The mechanical properties of engineering plastics can be enhanced through effective surface mechanical treatment(SMT),which can be applied to various types of engineering plastics,eliminating the limitations of conventional polymer processing and could potentially extend their applications and improve their performance and reliability as structural-functional materials.Inspired by metal forging,this work proposes a simple and effective SMT strategy to enhance the mechanical properties of polyamide 66(PA66).Tensile tests have shown that SMTed PA66 samples exhibit significant improvements in both Young’s modulus and ultimate tensile strength(UTS),with a 2104 MPa Young’s modulus,almost double that of the pristine samples,and a 35.56%increase in UTS,reaching 183 MPa.Additionally,the modulus within the localized SMTed surface layer could reach up to 14 GPa,which is approximately 14 times higher than that of the pristine sample.The Vickers hardness within the localized SMTed surface layer can be doubled,reaching 10.72 Hv,and the crystallinity can increase by approximately 20%compared to the untreated region.Furthermore,force field molecular dynamics(FFMD)simulations were conducted to investigate the ternary relationship between the SMT method,PA66’s molecular structure,and its properties.The combination of MD simulations and versatile structural characterizations provides evidence that the SMT method’s mechanism,under heat induction,results in a chain-combing procedure that changes the polymer’s molecular morphology microscopically and enhances its mechanical properties macroscopically.

关键词： Nylon 66 mechanical properties hardness crystallinity structural characterizations molecular dynamics simulation

Simulation and experiment of a photovoltaic—air source heat pump system with thermal energy storage for heating and domestic hot water supply

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Building Simulation 2023年第10期16卷 1897-1913页

作者： junyu Da Ming Li Guoliang Li Yunfeng wang Ying Zhang Solar Energy Research Institute Yunnan Normal UniversityNo.768Juxian StreetChenggong districtKunmingYunnan650500China

For China,the development of low-energy buildings is one of the necessary routes for achieving carbon neutrality.Combining photovoltaic(PV)with air source heat pump(ASHP)yields a great potential in providing heating and domestic hot water(DHW)supply in non-central heating areas.However,the diurnal and seasonal inconsistencies between solar availability and building heat load can severely affect the efficacy of solar energy systems.This study creates and numerically simulates a PV-ASHP system with thermal energy storage(TES)in transient system simulation software,TRNSYS.Experimental studies are conducted to validate the simulation model.The system’s yearly operational characteristics are simulated to reveal the energy conversion relationship between the system’s thermoelectric storage and heating and DHW demand.The results show that the synergy between heating and DHW simultaneously improves the direct utilization of solar energy compared to single heating.The yearly self-consumption and self-satisfaction rates of PV and the COP of the ASHP increase by 131.25%,10.53%and 9.56%,respectively.Solar energy contributes 55.54%to the system,with a PV capacity of 82 W per square meter of building area.This study provides fresh approaches to developing flexible building-integrated PV-ASHP technologies and balance of the energy exchange among the PV,building load and TES.

关键词： PV-ASHP TRNSYS heating and DHW thermal energy storage simulation and experiment

Engineering Research Progress of Electrochemical Microreaction Technology—A Novel Method for Electrosynthesis of Organic Chemicals

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Engineering 2021年第1期7卷 22-32页

作者： Siyuan Zheng junyu Yan Kai wang State Key Laboratory of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Electrochemical methods are environmentally friendly and have unique advantages in the synthesis of organic chemicals.However,their implementation is limited due to the complex transport problems posed by traditional electrochemical reactors.Recently,the application of microreaction technology in electrosynthesis studies has reduced the transport distance of ions and increased the specific surface area of electrodes,leading to efficient,successive,and easily scaled-up electrosynthesis technologies.In this review article,engineering advantages of using microchannels in electrosynthesis are discussed from process enhancement perspective.Flow patterns and mass transfer behaviors in recently reported electrochemical microreactors are analyzed,and prototypes for the reactor scale-up are reviewed.As a relatively new research area,many scientific rules and engineering features of electrosynthesis in microreactors require elucidation.Potential research foci,considered crucial for the development of novel electrosynthesis technology,are therefore proposed.

关键词： synthesis Electrochemical successive

An average-value-at-risk criterion for Markov decision processes with unbounded costs

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Frontiers of Mathematics in China 2022年第4期17卷 673-687页

作者： Qiuli LIU Wai-Ki CHING junyu ZHANG Hongchu wang School of Mathematical Sciences South China Normal UniversityGuangzhou510631China Advanced Modeling and Applied Computing Laboratory Department of MathematicsThe University of Hong KongHong KongChina School of Mathematics Sun Yat-Sen UniversityGuangzhou510275China

We study the Markov decision processes under the average-value-at-risk criterion.The state space and the action space are Borel spaces,the costs are admitted to be unbounded from above,and the discount factors are state-action dependent.Under suitable conditions,we establish the existence of optimal deterministic stationary policies.Furthermore,we apply our main results to a cash-balance model.

关键词： Markov decision processes average-value-at-risk(AVaR) state-action dependent discount factors optimal policy

Enlightenment from the COVID-19 Pandemic:The Roles of Environmental Factors in Future Public Health Emergency Response

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Engineering 2022年第1期8卷 108-115页

作者： Xiaolei wang Fengchang Wu Xiaoli Zhao Xiao Zhang Junyu wang Lin Niu Weigang Liang Kenneth Mei Yee Leung John P.Giesy State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China State Key Laboratory of Marine Pollution&Department of Chemistry City University of Hong KongHong KongChina Department of Veterinary Biomedical Sciences and Toxicology Centre University of SaskatchewanSaskatoonSK S7N 5E2Canada Department of Environmental Sciences Baylor UniversityWacoTX 76798USA

The coronavirus disease 2019(COVID-19)pandemic is challenging the current public health emergency response systems(PHERSs)of many countries.Although environmental factors,such as those influencing the survival of viruses and their transmission between species including humans,play important roles in PHERSs,little attention has been given to these factors.This study describes and elucidates the roles of environmental factors in future PHERSs.To improve countries’capability to respond to public health emergencies associated with viral infections such as the COVID-19 pandemic,a number of environmental factors should be considered before,during,and after the responses to such emergencies.More specifically,to prevent pandemic outbreaks,we should strengthen environmental and wildlife protection,conduct detailed viral surveillance in animals and hotspots,and improve early-warning systems.During the pandemic,we must study the impacts of environmental factors on viral behaviors,develop control measures to minimize secondary environmental risks,and conduct timely assessments of viral risks and secondary environmental effects with a view to reducing the impacts of the pandemic on human health and on ecosystems.After the pandemic,we should further strengthen surveillance for viruses and the prevention of viral spread,maintain control measures for minimizing secondary environmental risks,develop our capability to scientifically predict pandemics and resurgences,and prepare for the next unexpected resurgence.Meanwhile,we should restore the normal life and production of the public based on the“One Health”concept,that views global human and environmental health as inextricably linked.Our recommendations are essential for improving nations’capability to respond to global public health emergencies.

关键词： Public health emergency Public health emergency response system Environmental factors Prevention and control Viral infections

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Efficient synthesis of lithium rare-earth tetrafluoride nanocrystals via a continuous flow method

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Nano Research 2020年第10期13卷 2837-2846页

作者： Jinsong Sui junyu Yan Kai wang Guangsheng Luo The State Key Lab of Chemical Engineering Department of Chemical EngineeringTsinghua UniersityBeijing 100084China

As an important upconversion illuminant material, LiREF4 nanocrystals were efficiently synthesized in a continuous reactor with the assistant of a new precursor solution. The employed trioctylamine solvent in the solution had a strong interaction with HF, and helped to avoid the generation of unnecessary solid components as LiF and NH4REF4 during the reaction. A silicon carbide reactor was developed to carry out the synthesis reaction, where LiYF4:Yb,Er/Ho/Tm quickly nucleated in 5 min at 300℃. The reaction time to successfully prepare 15 nm sized nanocrystals was less than 30 min, and the space-time yield of the flow synthesis method was 14.8 times that of a control group batch reaction. The prepared nanocrystals had a strong illuminant ability, which could find its use in the area of security mark printing.

关键词： lithium rare earth tetrafluoride upconversion illuminant nanocyrstal silicon carbide reactor flow chemistry

Hybrid Semantic Service Matchmaking Method Based on a Random Forest

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Tsinghua Science and Technology 2020年第6期25卷 798-812页

作者： Wei Jiang junyu Lin Huiqiang wang Shichen Zou the College of Computer Science and Technology Harbin Engineering UniversityHarbin 150001China the Institute of Information Engineering Chinese Academy of SciencesBeijing 100093China Huawei Nanjing Research Institute Nanjing 210012China

Semantic Service Matchmaking(SSM)can be leveraged for mining the most suitable service to accommodate a diversity of user demands.However,existing research on SSM mostly involves logical or non-logical matching,leading to unavoidable false-positive and false-negative problems.Combining different types of SSM methods is an effective way to improve this situation,but the adaptive combination of different service matching methods is still a difficult issue.To conquer this difficulty,a hybrid SSM method,which is based on a random forest and combines the advantages of existing SSM methods,is proposed in this paper.The result of each SSM method is treated as a multi-dimensional feature vector input for the random forest,converting the service matching into a two classification problem.Therefore,our method avoids the flaws found in manual threshold setting.Experimental results show that the proposed method achieves an outstanding performance.

关键词： Semantic Service Matchmaking(SSM) random forest logic-based service matchmaking false-positive false-negative

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An approximation algorithm for lower-bounded k-median with constant factor

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Science China(Information Sciences) 2022年第4期65卷 93-101页

作者： Xiaoliang WU Feng SHI Yutian GUO Zhen ZHANG junyu HUANG Jianxin wang School of Computer Science and Engineering Central South University Hunan Provincial Key Lab on Bioinformatics Central South University School of Frontier Crossover Studies Hunan University of Technology and Business

The lower-bounded k-median problem plays a key role in many applications related to privacy protection, which requires that the amount of assigned client to each facility should not be less than the requirement. Unfortunately, the lower-bounded clustering problem remains elusive under the widely studied k-median objective. Within this paper, we convert this problem to the capacitated facility location problem and successfully give a(516+ε)-approximation for this problem.

关键词： Approximation algorithm approximation algorithm $k$-median lower-bounded $k$-median