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Thermal and mechanical characterization of under-2-μm-thick AlCrNbSiTi high-entropy thin film

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Energy Storage and Saving 2024年第1期3卷 52-59页

作者： Yibo Wang Xiaona Huang Yan Liu xiangyu zhang Bing Yang Yanan Yue School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China

High-entropy alloys(HEAs)exhibit extraordinary physical properties such as superior strength-to-weight ratios and enhanced corrosion and oxidation resistance,making them potentially useful in energy storage and gener-ation industries.However,thermal and mechanical properties of HEAs with various compositions vary signifi-cantly.Furthermore,these properties have rarely been investigated simultaneously owing to material or instru-mentation limitations.Herein,we synthesize an HEA(AlCrNbSiTi)coating with a thickness of less than 2μm.We customize a frequency-domain photothermal testing system to characterize the thermal and mechanical proper-ties of the proposed coating with high accuracy.Owing to the large mixing enthalpy of the Al-Ti,Nb-Si,and Ti-Si pairs in the coating,its hardness and elastic modulus are 15.2 and 254.7 GPa,respectively,which are higher than those of previously reported HEAs.The thermal conductivity of the AlCrNbSiTi coating is characterized to be 2.90 W·m^(−1)·K^(−1),within the expected range and well explained by the free-electron consistency diversity and phonon scattering from the amorphous structure.Additionally,the coating exhibits adequate wear performance,with a wear rate of 5.4×10^(−8) mm^(3)·N^(−1)·m^(−1).This relatively low thermal conductivity,combined with extraordi-nary mechanical properties,makes the proposed material an excellent candidate as a protective coating material for nuclear reactor components which require high strength,irradiation resistance,and thermal protection.

关键词： High-entropy alloys Thin coating Thermal conductivity Mechanical properties Noncontact photothermal technique

Impact of Regions with COVID-19 Cases on COVID-Zero Regions by Population Mobility—Worldwide,2021

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China CDC weekly 2022年第5期4卷 79-82,I0001-I0004页

作者： Lianhao Wang Shiyi Wang xiangyu zhang Zhongwei Jia School of Public Health Peking UniversityBeijingChina China Medical Science Press China Health Media GroupBeijingChina Center for Intelligent Public Health Institute for Artificial IntelligencePeking UniversityBeijingChina Center for Drug Abuse Control and Prevention National Institute of Health Data SciencePeking UniversityBeijingChina

Summary What is already known about this topic?Reducing population mobility and increasing the vaccination rate for severe acute respiratory syndrome coronavirus 2 can decrease the transmission of coronavirus disease 2019(COVID-19).What is added by this report?In order to reduce the incidence of COVID-19 to the levels of influenza after restoring normal mobility,the efficacy against infection needs to be increased to 40%and the efficacy against symptomatic disease needs to be increased to 90%.The efficacy against infection has a more important impact compared to efficacy against symptomatic disease or death on the transmission of COVID-19 at the population level.What are the implications for public health practice?The population should continue maintaining nonpharmaceutical interventions and minimize international movement to prevent transmission of COVID-19.Furthermore,developing new vaccines or promoting booster vaccinations should be considered to increase efficacy.

关键词： vaccination acute respiratory

Cost-effectiveness analysis on COVID-19 surveillance strategy of large-scale sports competition

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Infectious Diseases of Poverty 2022年第2期11卷 53-62页

作者： Xuechun Wang Yiru Cai Bo zhang xiangyu zhang Lianhao Wang xiangyu Yan Mingchen Zhao Yuan zhang Zhongwei Jia School of Public Health Peking UniversityBeijing 100191China School of Mathematical Sciences Peking UniversityBeijing 100871China Center for Statistical Sciences Peking UniversityBeijingChina Center for Intelligent Public Health Institute for Artifcial IntelligencePeking UniversityBeijingChina Peking University Clinical Research Institute Peking UniversityBeijingChina

Background:Nucleic acid test(NAT)could effectively control the spread of COVID-19 caused by large-scale sports competitions.However,quantitative analysis on the appropriate frequency of NAT is scarce,and the cost-effectiveness and necessity of high-frequency NAT remain to be fully explored and validated.This study aims to optimize the COVID-19 surveillance strategies through cost-effectiveness analysis for the Tokyo 2020 Olympic Games and the upcoming Beijing 2022 Olympic Winter Games.Methods:A total of 18 scenarios were designed regarding the NAT frequency,symptom monitoring,and strengthening close-contact control.An agent-based stochastic dynamic model was used to compare the cost-effectiveness of different NAT scenarios and optimize the surveillance strategies.The dynamics of the proposed model included the arrival and departure of agents,transmission of the disease according to Poisson processes,and quarantine of agents based on regular NATs and symptom onset.Accumulative infections,cost,and incremental cost-effectiveness ratio(ICER)were simulated in the frame of the model.ICER was used to compare the cost-effectiveness of different scenarios.Univariate sensitivity analysis was performed to test the robustness of the results.Results:In Scenario 16,where the competition-related personnel(CRP)received NAT daily and national sports delegation(NSD)with quarantined infections accepted an additional NAT daily,accumulative infection was 320.90(90 initial infections),the total cost was(United States Dollar)USD 8920000,and the cost of detecting out each infection was USD 27800.Scenario 16 would reduce the total cost by USD 22570000(avoid 569.61 infections),USD 1420000(avoid 47.2 infections)compared with Scenario 10(weekly NAT,strengthened close contact control)and Scenario 7(daily NAT,no strengthened close contact control),respectively.Sensitivity analysis showed that the result was most sensitive to the change in basic reproductive number.Conclusions:High-frequency NATs such as bidaily,daily,and twice a day were cost

关键词： Cost-effectiveness Sports competition Surveillance COVID-19 Nucleic acid test Stochastic dynamic model

Challenges and opportunities of machine learning control in building operations

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Building Simulation 2023年第6期16卷 831-852页

作者： Liang zhang Zhelun Chen xiangyu zhang Amanda Pertzborn Xin Jin The University of Arizona 1209 E 2nd StTucsonAZUSA Drexel University 3141 Chestnut StPhiladelphiaPAUSA National Renewable Energy Laboratory 15013 Denver W PkwyGoldenCOUSA National Institute of Standards and Technology 100 Bureau DrGaithersburgMDUSA

Machine learning control(MLC)is a highly flexible and adaptable method that enables the design,modeling,tuning,and maintenance of building controllers to be more accurate,automated,flexible,and adaptable.The research topic of MLC in building energy systems is developing rapidly,but to our knowledge,no review has been published that specifically and systematically focuses on MLC for building energy systems.This paper provides a systematic review of MLC in building energy systems.We review technical papers in two major categories of applications of machine learning in building control:(1)building system and component modeling for control,and(2)control process learning.We identify MLC topics that have been well-studied and those that need further research in the field of building operation control.We also identify the gaps between the present and future application of MLC and predict future trends and opportunities.

关键词： machine learning building operation control building energy system reinforcement learning

Regulation of TiO_(2) nanoarrays on titanium implants for enhanced osteogenic activity and immunomodulation

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Journal of Materials Science & Technology 2023年第19期150卷 233-244页

作者： Ruoyu Li Hongyu zhang Xiaohong Yao Bin Tang Paul K Chu xiangyu zhang Shanxi Key Laboratory of Biomedical Metal Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China Department of Occupational Disease Second Hospital of Shanxi Medical UniversityTaiyuan 030001China Department of Physics Department of Materials Science and Engineeringand Department of Biomedical EngineeringCity University of Hong KongTat Chee AvenueKowloonHong KongChina College of Biomedical Engineering Taiyuan University of TechnologyTaiyuan 030024China

The surface topography of implants plays a major role in osteogenesis and immunomodulation.In this study,three types of TiO_(2) nanoarrays including nanorod arrays with a diameter of 45 nm(TiO_(2)-N),nanorod arrays with a diameter of 60 nm(TiO_(2)-N N),and nanocone arrays(TiO_(2)-NW)are prepared on titanium and the behavior of bone marrow stromal cells(BMSCs)and polarization of macrophages are studied.Compared to the planar titanium control,TiO_(2) nanoarrays facilitate osteogenesis of BMSCs and stimulate the pro-healing M2 phenotype.However,adhesion,spreading,proliferation,and osteogenic differentiation of BMSCs are more pronounced on TiO_(2)-N N than both TiO_(2)-N and TiO_(2)-NW.TiO_(2)-NN also produces the best immune microenvironment,while TiO_(2)-NW is more favorable than TiO_(2)-NN from the viewpoint of cell adhesion and spreading of osteoblasts.

关键词： TiO_(2)nanoarrays Osteogenic activity Immunomodulation Hydrothermal treatment

Reinforcement learning building control approach harnessing imitation learning

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Energy and AI

Energy and AI 2023年第4期14卷 60-72页

作者： Sourav Dey Thibault Marzullo xiangyu zhang Gregor Henze Department of Civil Environmental and Architectural EngineeringUniversity of ColoradoBoulderCOUSA National Renewable Energy Laboratory GoldenCOUSA Renewable and Sustainable Energy Institute BoulderCOUSA

Reinforcement learning(RL)has shown significant success in sequential decision making in fields like autonomous vehicles,robotics,marketing and gaming industries.This success has attracted the attention to the RL control approach for building energy systems which are becoming complicated due to the need to optimize for multiple,potentially conflicting,goals like occupant comfort,energy use and grid interactivity.However,for real world applications,RL has several drawbacks like requiring large training data and time,and unstable control behavior during the early exploration process making it infeasible for an application directly to building control tasks.To address these issues,an imitation learning approach is utilized herein where the RL agents starts with a policy transferred from accepted rule based policies and heuristic policies.This approach is successful in reducing the training time,preventing the unstable early exploration behavior and improving upon an accepted rule-based policy-all of these make RL a more practical control approach for real world applications in the domain of building controls.

关键词： Reinforcement learning Building controls Imitation learning Artificial intelligence

A necessary considering factor for breeding:growth-defense tradeoff in plants

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Stress Biology 2023年第1期3卷 84-94页

作者： Hong zhang Yuanming Liu xiangyu zhang Wanquan Ji Zhensheng Kang State Key Laboratory of Crop Stress Biology for Arid Areas College of AgronomyNorthwest A&F UniversityYanglingShaanxi 712100People’s Republic of China State Key Laboratory of Crop Stress Biology for Arid Areas College of Plant ProtectionNorthwest A&F UniversityYanglingShaanxi 712100People’s Republic of China

Crop diseases cause enormous yield losses and threaten global food security.Deployment of resistant cultivars can effectively control the disease and to minimize crop losses.However,high level of genetic immunity to disease was often accompanied by an undesired reduction in crop growth and yield.Recently,literatures have been rapidly emerged in understanding the mechanism of disease resistance and development genes in crop plants.To determine how and why the costs and the likely benefit of resistance genes caused in crop varieties,we re-summarized the present knowledge about the crosstalk between plant development and disease resistance caused by those genes that function as plasma membrane residents,MAPK cassette,nuclear envelope(NE)channels components and pleiotropic regulators.Considering the growth-defense tradeoffs on the basis of current advances,finally,we try to understand and suggest that a reasonable balancing strategies based on the interplay between immunity with growth should be considered to enhance immunity capacity without yield penalty in future crop breeding.

关键词： Crops Growth-defense Reasonable cell death Yield penalty

Analysis for magnetic field disturbance of modular multilevel converter based high voltage direct current(MMC-HVDC)converter valve

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High Voltage 2023年第1期8卷 91-101页

作者： Lei Qi Muxue Wang xiangyu zhang Hong Shen Hongyu Wang Chongqing Jiao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

The standardised design and operational reliability enhancement of the flexible DC converter valve are impending with the construction of high shares of renewables and power electronics power system.A power frequency magnetic field calculation model able to obtain the electromagnetic disturbance at the submodule(SM)drive board during normal operation of a flexible DC converter valve is presented.Hundreds of SMs with complex structures in a converter valve tower are simplified by the equivalent to the line current to fulfil calculation accuracy requirements.In addition,a random function is employed to simulate the non-sequential switching process of the SMs.By comparing the calculated results with the measured data obtained from the SM equivalent operation experiment of 2200 V/2150 A,the validity of the calculation model is confirmed.According to the final calculations,the influence of non-sequential switching cannot be ignored when recognising the time-domain distribution features of the power frequency magnetic field of the drive board.However,engineering design can be guided only by the power frequency magnetic field intensity of the drive board calculated based on SM’s full removal in the valve tower.

关键词： disturbance converter magnetic

Experimental study on ageing characteristics of electric locomotive ethylene propylene rubber cable under mechanical-thermal combined action

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High Voltage 2022年第4期7卷 792-801页

作者： Lijun Zhou Cong Liu Shengwei Quan xiangyu zhang Dongyang Wang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The train-mounted ethylene propylene rubber(EPR)cables of electric locomotive are partly restricted by the body structure and spatial layout and are in a combined envi-ronment of strong mechanical bending and thermal ageing.The degradation character-istics of the insulation layer have not yet received sufficient attention.In order to study the ageing characteristics of EPR cables of electric locomotive under the combined action of machine and thermal,this paper designs a bending-thermal combined ageing test platform for cables with a temperature of 135°C,bending diameter of 393.52 mm,590.28 mm and unbending cables,and tests after ageing.The product has been tested by infrared spectroscopy,scanning electron microscopy,elongation at break and broadband dielectric spectroscopy.The research results show that the bending outer part of the train-mounted EPR cable is a pain point.Under the combined action of bending and thermal,whether it is microstructure or macro performance,the degradation rate and degree of the bending of outer insulation layer are greater than the value under a single thermal ageing condition.Mechanical bending has an accelerating effect on the ageing of the EPR insulation layer.The research results can provide a reference for the ageing characteristics of the train-mounted EPR cable under the bending-thermal synergy and the evaluation of operating state of the train-mounted EPR cable under bending-thermal operating conditions.

关键词： microstructure thermal bending