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Effect of annealing time and phosphorus addition on bake hardening behavior of ultra-low carbon bake hardening steel

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Journal of Iron and Steel Research(International) 2018年第12期25卷 1287-1295页

作者： Xi-liang Zhang Hua-feng Hou Tao Liu Qian Zhou Hong-ji Liu Yu-long Zhang hao-xuan cui Zheng Lv College of Mechanical and Equipment Engineering Hebei University of EngineeringHandan 056038HebeiChina

The relationship of the P and C grain boundary segregation and its effect on bake hardening behavior were investigated in ultra-low carbon bake hardening (ULC-BH)steel with and without P addition annealed at 810 ℃ for various time using electron probe micro-analyzer,electroh backscattered diffraction,and three-dimensional atomic probe techniques.Results revealed that P addition and annealing duration considerably affected the bake hardening behavior of experimental steel. The BH value of ULC-BH steel without P addition is lower than that with P addition within a short annealing time,and the difference in the BH value gradually decreases as the annealing duration is prolonged.P segregation is dominant in terms of a high P bulk content in steels with P addition at the expense of C segregation during annealing.By contrast,opposite effects are observed in low carbon bake hardening steel.The high residual solute C content in steel with P addition is due to P segregation at the grain boundary.Site competition is mainly responsible for the lower BH value in ULC-BH steel without P addition than that with P addition.As the annealing time is further extended,C segregation begins at grain boundary despite the delayed P segregation,leading to a gradual decrease in the solute concentration in the matrix of steels with P addition.C and P segregations reach the equilibrium as the annealing time increases to 60 min at 810 ℃ in the two steel samples.Theoretical calculations reveal that the residual solute C concentration in the matrix decreases to zero,and this finding is consistent with the change trend of the bake hardening value.Hence,the C segregation at grain boundary. adversely influences the bake hardening property of ULC-BH steel.

关键词： Ultra-low carbon bake hardening steel Carbon Phosphorus addition Bake hardening behavior Grain boundary segregation

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Modified constitutive models for Inconel 718 considering current density and temperature in electrically assisted forming process

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Chinese Journal of Aeronautics 2024年第2期37卷 524-540页

作者： xuan cui Rui Zhao Min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

Electrically Assisted Forming(EAF)technology has obvious advantages in material forming.To develop an effective constitutive model considering electrical effects,room temperature and electrically assisted quasi-static uniaxial tensile tests were conducted using ultrathin nickelbased superalloy plates with a thickness of 0.25 mm.The research focused on the two most widely recognized effects:the Joule thermal and the electric athermal effects.The mechanism of current action can be divided into two scenarios:one considering the Joule thermal effect only,and the other considering both effects simultaneously.Two basic constitutive models,namely the Modified-Hollomon model and the Johnson-Cook(J-C)model,were selected to be optimized through the classification of two different situations,and four optimized constitutive models were proposed.It was found that the J-C model with simultaneous consideration of the Joule thermal effect and electric athermal effect had the best prediction effect by comparing the results of these four models.Finally,the accuracy of the optimization model was verified by finite element simulation of the electrically assisted stretching optimization model.The results show that the constitutive model can effectively predict the temperature effect caused by the Joule heat effect and the athermal effect of current on the material.

关键词： Joule heating Elastoplasticity Plastic deformation Superalloys Constitutive models

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Total-factor energy efficiency of ten major global energy-consuming countries

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Journal of Environmental Sciences 2024年第3期137卷 41-52页

作者： xuan Wang Yonglong Lu Chunci Chen Xiaojie Yi haotian cui State Key Laboratory of Urban and Regional Ecology Research Centre for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China State Key Laboratory of Marine Environmental Science and Key Laboratory of the Ministry of Education for Coastal Wetland Ecosystems College of the Environment and EcologyXiamen UniversityFujian 361102China University of Chinese Academy of Sciences Beijing 100049China

Improving energy efficiency is regarded as a key path to tackling global warming and achieving the Sustainable Development Goals(SDGs).In 2020,the energy consumption of the world's ten major energy-consuming countries accounted for 66.8%of the global total.This paper applied data envelopment analysis(DEA)to calculate these ten major energyconsuming countries'total-factor energy efficiency(TFEE)at national and sectoral levels from 2001-2020,and explored the infuencing factors of total-factor energy efficiency with the Tobit regression model.The results showed significant difference in the ten countries'energy efficiency.The United States and Germany topped the list for total-factor energy efficiency,while China and India were at the bottom.Meanwhile,the energy efficiency of the industrial subsector has increased significantly over the past two decades,while that of the other subsectors has been relatively fat.The industrial structure upgrading,per capita GDP,energy consumption structure,and foreign direct investment had significant impacts on energy efficiency with national heterogeneity.Energy consumption structure and GDP per capita were determinative factors of energy efficiency.

关键词： Total-factor energy efficiency SBM-UN model Major energy-consuming country Carbon emission reduction

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Nano-effect enhanced cooperative luminescence of Yb^(3+) clusters in bulk materials

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Journal of Rare Earths 2024年第3期42卷 473-478,I0002页

作者： Daguang Li Jiahao cui Yanhui Dong hao cui Dan Zhao Weiping Qin State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun130012China

In order to improve the multi-ion cooperative transition, we proposed and exploited a novel nanoscale effect, namely the nanoshell effect in bulk materials. Based on the effect, an optimal material structure was designed by coating the surfaces of Ca F_(2):Yb^(3+)micron size particles with ZrO_(2). An about 2 times higher intensity of cooperative luminescence is observed upon laser excitation at 980 nm. Dynamical analysis exhibits that the novel effect plays a key role in improving the performance of cooperative transitions. Our results also suggest that the nanoshell effect in bulk materials is likely to be significant in some special cases, which have not been reported yet in the literature.

关键词： Yb^(3+)cluster ZrO_(2) Nanoshell Enhancement Cooperative luminescence Rare earths

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Continuous-Time Channel Prediction Based on Tensor Neural Ordinary Differential Equation

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China Communications 2024年第1期21卷 163-174页

作者： Mingyao cui hao Jiang Yuhao Chen Yang Du Linglong Dai The Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Huawei Technology Co. Ltd.Chengdu Research InstituteChengdu 611730China

Channel prediction is critical to address the channel aging issue in mobile scenarios.Existing channel prediction techniques are mainly designed for discrete channel prediction,which can only predict the future channel in a fixed time slot per frame,while the other intra-frame channels are usually recovered by interpolation.However,these approaches suffer from a serious interpolation loss,especially for mobile millimeter-wave communications.To solve this challenging problem,we propose a tensor neural ordinary differential equation(TN-ODE)based continuous-time channel prediction scheme to realize the direct prediction of intra-frame channels.Specifically,inspired by the recently developed continuous mapping model named neural ODE in the field of machine learning,we first utilize the neural ODE model to predict future continuous-time channels.To improve the channel prediction accuracy and reduce computational complexity,we then propose the TN-ODE scheme to learn the structural characteristics of the high-dimensional channel by low-dimensional learnable transform.Simulation results show that the proposed scheme is able to achieve higher intra-frame channel prediction accuracy than existing schemes.

关键词： channel prediction massive multipleinput-multiple-output millimeter-wave communications ordinary differential equation

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Efficient single‑pixel imaging based on a compact fiber laser array and untrained neural network

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Frontiers of Optoelectronics 2024年第1期17卷 85-93页

作者： Wenchang Lai Guozhong Lei Qi Meng Yan Wang Yanxing Ma hao Liu Wenda cui Kai Han College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Nanhu Laser Laboratory National University of Defense TechnologyChangsha 410073China

This paper presents an efficient scheme for single-pixel imaging(SPI)utilizing a phase-controlled fiber laser array and an untrained deep neural network.The fiber lasers are arranged in a compact hexagonal structure and coherently combined to generate illuminating light fields.Through the utilization of high-speed electro-optic modulators in each individual fiber laser module,the randomly modulated fiber laser array enables rapid speckle projection onto the object of interest.Furthermore,the untrained deep neural network is incorporated into the image reconstructing process to enhance the quality of the reconstructed images.Through simulations and experiments,we validate the feasibility of the proposed method and successfully achieve high-quality SPI utilizing the coherent fiber laser array at a sampling ratio of 1.6%.Given its potential for high emitting power and rapid modulation,the SPI scheme based on the fiber laser array holds promise for broad applications in remote sensing and other applicable fields.

关键词： Single-pixel imaging Fiber laser array Deep learning Remote sensing

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Ballistic performance of additive manufacturing 316l stainless steel projectiles based on topology optimization method

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Defence Technology（防务技术） 2024年第5期35卷 1-17页

作者： hao Xue Tao Wang Xinyu cui Yifan Wang Guangyan Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.

关键词： Additive manufacturing Topology optimization Ballistic performance Projectile design

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Modelling the viscoplastic behaviour of Callovo-Oxfordian claystone with consideration of damage effect

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 303-316页

作者： hao Wang Yu-Jun cui Minh Ngoc Vu Jean Talandier Ecole des Ponts ParisTech Laboratoire Navier/CERMES6 et 8 avenue Blaise PascalMarne La Vallée cedex 277455France Andra R&D DepartmentChâtenay-Malabry92290France

In order to evaluate the performance of deep geological disposal of radioactive waste,an underground research laboratory(URL)was constructed by Andra in the Callovo-Oxfordian(COx)claystone formation at the Meuse/Haute-Marne(MHM).The construction of URL induced the excavation damage of host formations,and the ventilation in the galleries desaturated the host formation close to the gallery wall.Moreover,it is expected that the mechanical behaviour of COx claystone is time-dependent.This study presents a constitutive model developed to describe the viscoplastic behaviour of unsaturated and damaged COx claystone.In this model,the unsaturation effect is considered by adopting the Bishop effective stress and the van Genuchten(VG)water retention model.In terms of the viscoplastic behaviour,the nonstationary flow surface(NSFS)theory for unsaturated soils is used with consideration of the coupled effects of strain rate and suction on the yield stress.A progressive hardening law is adopted.Meanwhile,a non-associated flow rule is used,which is similar to that in Barcelona basic model(BBM).In addition,to describe the damage effect induced by suction change and viscoplastic loading,a damage function is defined based on the crack volume proportion.This damage function contains two variables:unsaturated effective stress and viscoplastic volumetric strain,with the related parameters determined based on the mercury intrusion porosimetry(MIP)tests.For the model validation,different tests on COx claystone under different loading paths are simulated.Comparisons between experimental and simulated results indicated that the present model is able to well describe the viscoplastic behaviour of damaged COx claystone,including swelling/shrinkage,triaxial extension and compression,and triaxial creep.

关键词： Callovo-Oxfordian(COx)claystone Excavation damage Time-dependent behaviour Suction Viscoplastic model

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Metabolic memory:mechanisms and diseases

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Signal Transduction and Targeted Therapy 2024年第3期9卷 1086-1114页

作者： hao Dong Yuezhang Sun Lulingxiao Nie Aimin cui Pengfei Zhao Wai Keung Leung Qi Wang State Key Laboratory of Oral Diseases&National Center for Stomatology&National Clinical Research Center for Oral Diseases West China Hospital of StomatologySichuan UniversityChengduChina Department of Prosthodontics West China Hospital of StomatologySichuan UniversityChengduChina Periodontology and Implant Dentistry Division Faculty of DentistryThe University of Hong KongHong KongChina

Metabolic diseases and their complications impose health and economic burdens worldwide.Evidence from past experimental studies and clinical trials suggests our body may have the ability to remember the past metabolic environment,such as hyperglycemia or hyperlipidemia,thus leading to chronic inflammatory disorders and other diseases even after the elimination of these metabolic environments.The long-term effects of that aberrant metabolism on the body have been summarized as metabolic memory and are found to assume a crucial role in states of health and disease.Multiple molecular mechanisms collectively participate in metabolic memory management,resulting in different cellular alterations as well as tissue and organ dysfunctions,culminating in disease progression and even affecting offspring.The elucidation and expansion of the concept of metabolic memory provides more comprehensive insight into pathogenic mechanisms underlying metabolic diseases and complications and promises to be a new target in disease detection and management.Here,we retrace the history of relevant research on metabolic memory and summarize its salient characteristics.We provide a detailed discussion of the mechanisms by which metabolic memory may be involved in disease development at molecular,cellular,and organ levels,with emphasis on the impact of epigenetic modulations.Finally,we present some of the pivotal findings arguing in favor of targeting metabolic memory to develop therapeutic strategies for metabolic diseases and provide the latest reflections on the consequences of metabolic memory as well as their implications for human health and diseases.

关键词： diseases metabolism alterations

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Analysis and Optimization of the Electrohydraulic Forming Process of Sinusoidal Corrugation Tubes

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Fluid Dynamics & Materials Processing 2024年第4期20卷 873-887页

作者： Da Cai Yinlong Song hao Jiang Guangyao Li Junjia cui State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan UniversityChangsha410082China

Aluminum alloy thin-walled structures are widely used in the automotive industry due to their advantages related to light weight and crashworthiness.They can be produced at room temperature by the electrohydraulic forming process.In the present study,the influence of the related parameters on the forming quality of a 6063 aluminum alloy sinusoidal corrugation tube has been assessed.In particular,the orthogonal experimental design(OED)and central composite design(CCD)methods have been used.Through the range analysis and variance analysis of the experimental data,the influence degree of wire diameter(WD)and discharge energy(DE)on the forming quality was determined.Multiple regression analysis was performed using the response surface methodology.A prediction model for the attaching-die state coefficient was established accordingly.The following optimal arrangement of parameters was obtained(WD=0.759 mm,DE=2.926 kJ).The attaching-die state coefficient reached the peak value of 0.001.Better optimized wire diameter and discharge energy for a better attaching-die state could be screened by CCD compared with OED.The response surface method in CCD was more suitable for the design and optimization of the considered process parameters.

关键词： Electrohydraulic forming aluminum alloy tube process parameters attaching-die state 1 Introduction

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