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Inertial Subgradient Extragradient Algorithm for Solving Variational Inequality Problems with Pseudomonotonicity

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哈尔滨工业大学学报:英文版 2023年第5期30卷 65-75页

作者： Yuwan Ding Hongwei Liu Xiaojun Ma School of Mathematics and Statistics Xidian UniversityXi’an710126China

In order to solve variational inequality problems of pseudomonotonicity and Lipschitz continuity in Hilbert spaces, an inertial subgradient extragradient algorithm is proposed by virtue of non-monotone stepsizes. Moreover, weak convergence and R-linear convergence analyses of the algorithm are constructed under appropriate assumptions. Finally, the efficiency of the proposed algorithm is demonstrated through numerical implementations.

关键词： variational inequality extragradient method pseudomonotonicity Lipschitz continuity weak and linear convergence

Limitations of the homogenization process of bulk martensitic mold steel-depending on the comprehensive manifestation of various strengthening

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Journal of Materials Science & Technology 2022年第22期117卷 120-132页

作者： Hanghang liu Paixian Fu Hongwei Liu Chen Sun Ningyu Du Dianzhong Li Shenyang National Laboratory for Materials Science Shenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

A homogenization treatment(1250 °C + 12 h) was carried out to minimize the micro-segregation of bulk 718H martensitic mold steel, as verified by advanced experimental characterization and kinetic model of diffusion. However, new research found that there are still limitations in the use of the homogenization process. The result indicates that the chemical heterogeneity can be significantly reduced after homogenization. The segregation ratio of Cr and Mo elements of sample decreased by 40.9% and 35.6% of the original level, respectively. Simultaneously, the test steel with higher strength and toughness is produced by controlling micro-segregation tempered from 540 °C to 650 °C. Importantly, it reveals that the impact energy is increased by up to 27.3%. The isotropy of impact energy in different directions can reach 0.89,resulting in an overall improvement in the isotropy. Toughness mainly depends on the orientation relationship between the crack propagation direction and the band segregation region. The chain carbides formed due to the decomposition of the micro-segregated region during tempering are considered the main source of cracks. The more evenly distributed the subsequent tempered carbides after homogenization, resulting in an increase in toughness. However, an abnormal phenomenon is found in which the yield strength after homogenization is lower than that of the untreated sample tempered at 700 °C. This result can be attributed to the combined influences of precipitation strengthening and fine grain strengthening by analyzing various strengthening mechanisms. The mutually restrictive strengthening effect leads to the limitations of the homogenization process of bulk martensitic mold steel.

关键词： Martensitic mold steel Strength-toughness Micro-segregation Synergistic strengthening

Characterizations of the biomineralization film caused by marine Pseudomonas stutzeri and its mechanistic effects on X80 pipeline steel corrosion

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Journal of Materials Science & Technology 2022年第30期125卷 15-28页

作者： Haixian liu Wen Chen Yu Tan Guozhe Meng Hongfang liu YFrank Cheng Hongwei Liu School of Chemical Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China Research Institute of Natural Gas Technology Southwest Oil&Gasfield CompanyChina National Petroleum CorporationChengdu 610000China Department of Mechanical and Manufacturing Engineering University of CalgaryCalgaryAlberta T2N 1N4Canada Key Laboratory for Large-Format Battery Materials and System Ministry of EducationHubei Key Laboratory of Materials Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Microbiologically influenced corrosion(MIC)of steel generates a corrosion product film,which can also be called biomineralization film.It is critical to understand the structure of biomineralization film since it dominates the corrosion behavior of metal.In this work,Pseudomonas stutzeri(P.stutzeri)was isolated from seawater,and the biomineralization film caused by marine P.stutzeri was characterized by Transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),etc.The mechanistic effects of the biomineralization film on X80 pipeline steel corrosion were also investigated.The results indicate that the minerals are mainly composed of nano FeOand FeOOH,according to TEM and XRD results.The particle sizes of biominerals are below 10 nm.This work also provides an insight strategy to prepare nanomaterials by MIC caused by P.stutzeri.In addition,P.stutzeri can grow well with COas a carbon source and iron as an electron donor.The corrosion rates(CRs)of specimens are closely related to the structure of biomineralization film.The CRs increase with the decrease of initial cell concentration.P.stutzeri with an initial concentration of 10~7 cells/mL can promote the formation of a compact biomineralization film with a thickness of 145.8±4.8μm,leading to corrosion inhibition with a CR of 0.058±0.008 mm/y.But some corrosion pits can be observed due to the formation of small anodes.Electrochemical impedance spectroscopy(EIS)data show higher impedance values and two time-constants,which imply the formation of a compact biomineralization film.

关键词： Biomineralization Nanomaterials MIC Pseudomonas stutzeri Steel

Making True Amplitude Angle Domain Common Image Gathers Using Invertible Radon Transform

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Communications in Computational Physics 2020年第6期28卷 128-140页

作者： Hongwei Liu Yi Luo EXPEC Advanced Research Center Saudi Arabia

Converting subsurface offset domain common image gathers(ODCIGs)to angle domain common image gathers(ADCIGs)through a Radon Transform(RT)in either the spatial or wavenumber domain is efficient and valid except for the distortion of both frequency spectrum and amplitude versus angle(AVA)effect.This paper presents two modifications to the existing method to keep the frequency spectrum of the resultant ADCIGs the same as the input data and to preserve the relative amplitudes.The spectrum invariance is achieved by replacing the conventional RT or slant slack by an invertible RT.Amplitude preservation is obtained by applying an amplitude correction factor in the angle domain.Tests on both synthetic and field datasets validate the accuracy of these modifications.

关键词： True amplitude ADCIG reverse time migration invertible Radon transform

Subspace Minimization Conjugate Gradient Method Based on Cubic Regularization Model for Unconstrained Optimization

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Journal of Harbin Institute of Technology(New Series) 2021年第5期28卷 61-69页

作者： Ting Zhao Hongwei Liu School of Mathematics and Statistics Xidian UniversityXi'an 710126China

Many methods have been put forward to solve unconstrained optimization problems,among which conjugate gradient method(CG)is very important.With the increasing emergence of large⁃scale problems,the subspace technology has become particularly important and widely used in the field of optimization.In this study,a new CG method was put forward,which combined subspace technology and a cubic regularization model.Besides,a special scaled norm in a cubic regularization model was analyzed.Under certain conditions,some significant characteristics of the search direction were given and the convergence of the algorithm was built.Numerical comparisons show that for the 145 test functions under the CUTEr library,the proposed method is better than two classical CG methods and two new subspaces conjugate gradient methods.

关键词： cubic regularization model conjugate gradient method subspace technique unconstrained optimization

Path planning of hyper‐redundant manipulators for narrow spaces

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IET Cyber-Systems and Robotics 2022年第3期4卷 251-263页

作者： Haoxiang Su Manlu liu Hongwei Liu Jianwen Huo Songlin Gou Qing Su School of Information Engineering Southwest University of Science and TechnologyMian YangChina Robot Technology Used for Special Environment Key Laboratory of Sichuan Province Mian YangChina School of Manufacturing Science and Engineering Southwest University of Science and TechnologyMian YangChina

Compared with the traditional manipulator,the hyper‐redundant manipulator has the advantage of high flexibility,which is particularly suitable for all kinds of complex working environments.However,the complex space environment requires the hyper‐redundant manipulator to have stronger obstacle avoidance ability and adaptability.In order to solve the problems of a large amount of calculation and poor obstacle avoidance effects in the path planning of the hyper‐redundant manipulator,this paper introduces the‘backbone curve’approach,which transforms the problem of solving joint path points into the behaviour of determining the backbone curve.After the backbone curve approach is used to design the curve that meets the requirements of obstacle avoidance and the end pose,the least squares fitting and the improved space joint fitting are used to match the plane curve and the space curve respectively,and the angle value of each joint of the manipulator is limited by the algorithm.Furthermore,a fusion obstacle avoidance algorithm is proposed to obtain the joint path points of the hyper‐redundant manipulator.Compared with the classic Jacobian iteration method,this method can avoid obstacles better,has the advantages of simple calculation,high efficiency,and can fully reflect the geometric characteristics of the manipulator.Simulation experiments have proven the feasibility of the algorithm.

关键词： convergence dexterous manipulators geometric algebra motion planning

Exploring the ultrahigh rolling contact fatigue life of M50 bearing steel by adjusting the cryogenic sequence

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Journal of Materials Science & Technology 2024年第2期169卷 243-250页

作者： Xin Cai Xiaoqiang Hu Xingyu Lu Hongwei Liu Yanfei Cao Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The influence of different cryogenic sequences on the rolling contact fatigue(RCF)life of M50-bearing steel has been studied.The results show that direct cryogenic treatment after quenching can effectively improve RCF life.The L_(10)life is strikingly 5 times longer than that with cryogenic treatment after tem-pering.This is caused by the distinct lattice construction of martensite and the transformation of retained austenite.More secondary nanocarbides and fine twins are formed via cryogenic treatment before tem-pering compared with cryogenic treatment after tempering.The improvement in the RCF life of the steel is attributed to the joint effects of the secondary nanocarbides and twin boundaries with a width of 5-13 nm,which delays significantly crack initiation and propagation.This study highlights a common method to improve the service life of high-carbon and high-alloy steels by adjusting the cryogenic se-quence.

关键词： M50 steel Cryogenic treatment Rolling contact fatigue life Carbide Twin

Building State-owned Assets Supervision System and Conducting Mixed Ownership Reforms to Reinforce Each Other’s Collaboration

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Frontiers of Business Research in China 2022年第1期16卷 70-87页

作者： LIAO hongwei liu Yongfei Center for China Public Sector Economy Research Jilin UniversityChangchun 130012China School of Economics Jilin UniversityChangchun 130012China

Improving the state-owned assets supervision system(SOASS)can effectively get over the defects of systems and mechanisms and further promote the reform of mixed ownership of state-owned enterprises(SOEs);and the deepening of the reform can advance the change of the SOASS to the supervision on capital.By analyzing the relationship between the SOASS and the reform of mixed ownership of state-owned enterprises,we have found that collaborative promotion of the change of the SOASS to the supervision on capital and promotion of the reform of mixed ownership can do good to ameliorating the corporate management mechanism,improving the market-oriented management mechanism of enterprises and completing the medium-and long-term incentive mechanisms,etc.to enhance business operation efficiency.Due to such prevailing problems as relative dispersion and vagueness of the policies relating to deepening the reform of SOEs,inconsistent progress of the reform of state-owned assets(SOAs)and SOEs,and corporate reform focusing on apprence,improving the SOASS and deepening collaborative development of the reform of mixed ownership of SOEs are hindered by some constraints.To construct and improve the SOASS and the reform of mixed ownership collaboratively,we should make efforts to promote the reform in the following five aspects,namely,placing importance to policy coordination,boosting synchronism of the reform of SOAs and SOEs at different levels and in different areas to coordinate the nationwide reform of SOAs and SOEs,facilitating reform of the mechanism of enterprises of mixed ownership through mixed capital,and promoting the SOASS and stimulating classified monitoring and reform of mixed ownership based on classified reform of SOEs.

关键词： state-owned assets supervision system(SOASS) state-owned enterprises(SOEs) reform of mixed ownership corporation for state-owned capital investment and operation

Triple-Helix Structured Model Based on Problem-Knowledge-Solution Co-evolution for Innovative Product Design Process

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 49-63页

作者： Qian Hui Yan Li Ye Tao Hongwei Liu Innovation Method and Creative Design Key Laboratory of Sichuan Province Chengdu610065China School of Mechanical Engineering Sichuan UniversityChengdu610065China

A design problem with deficient information is generally described as wicked or ill-defined.The information insufficiency leaves designers with loose settings,free environments,and a lack of strict boundaries,which provides them with more opportunities to facilitate innovation.Therefore,to capture the opportunity behind the uncertainty of a design problem,this study models an innovative design as a composite solving process,where the problem is clarified and resolved from fuzziness to satisfying solutions by interplay among design problems,knowledge,and solutions.Additionally,a triple-helix structured model for the innovative product design process is proposed based on the co-evolution of the problem,solution,and knowledge spaces,to provide designers with a distinct design strategy and method for innovative design.The three spaces interact and co-evolve through iterative mappings,including problem structuring,knowledge expansion,and solution generation.The mappings carry the information processing and decision-making activities of the design,and create the path to satisfying solutions.Finally,a case study of a reactor coolant flow distribution device is presented to demonstrate the practicability of this model and the method for innovative product design.

关键词： Innovative design Problem-knowledge-solution co-evolution Design activity Design process Product design