检索结果-南通市图书馆

Machine learning of mechanical properties of steels

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2020年第7期63卷 1247-1255页

作者： xiong jie ZHANG TongYi SHI SanQiang Materials Genome Institute Shanghai UniversityShanghai 200444China Department of Mechanical Engineering the Hong Kong Polytechnic UniversityHong Kong 999077China Shenzhen Research Institute the Hong Kong Polytechnic UniversityShenzhen 518057China

Knowledge of the mechanical properties of structural materials is essential for their practical applications. In the present work,three-hundred and sixty data samples on four mechanical properties of steels—fatigue strength, tensile strength, fracture strength and hardness—were selected from the Japan National Institute of Material Science database, comprising data on carbon steels and low-alloy steels. Five machine learning algorithms were used to predict the mechanical properties of the materials represented by the three-hundred and sixty data samples, and random forest regression showed the best predictive *** selection conducted by random forest and symbolic regressions revealed the four most important features that most influence the mechanical properties of steels: the tempering temperature of steel, and the alloying elements of carbon, chromium and molybdenum. Mathematical expressions were generated via symbolic regression, and the expressions explicitly predicted how each of the four mechanical properties varied quantitatively with the four most important features. This study demonstrates the great potential of symbolic regression in the discovery of novel advanced materials.

关键词： materials informatics steel fatigue strength symbolic regression

Some Limit Theorems for a Particle System of Single Point Catalytic Branching Random Walks

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2007年第6期23卷 997-1012页

作者： Vladimir VATUTIN jie xiong Steklov Mathematical Institute Gubkin street 8 119991 Moscow Russia Department of Mathematics University of Tennessee Knoxville TN 37996 1300 USA Department of Mathematics Hebei Normal University Shijiazhuang 050016 P. R. China

We study the scaling limit for a catalytic branching particle system whose particles perform random walks on Z and can branch at 0 only. Varying the initial （finite） number of particles, we get for this system different limiting distributions. To be more specific, suppose that initially there are n^β particles and consider the scaled process Zt^n（·） = Znt（√n·）, where Zt is the measure-valued process 1 and to a representing the original particle system. We prove that Ztn converges to 0 when β 〈1/4 and to a nondegenerate discrete distribution when β=1/*** addition,if 1/4〈β〈1/2 then n-^（2β-1/2）Zt^n converges to a random limit,while if β 〉21then n^-βZtn converges to a deterministic limit.

关键词： Renewal equation branching particle system scaling limit

Stochastic maximum principle for partially observed forward-backward stochastic differential equations with jumps and regime switching

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第7期61卷 106-118页

作者： Shuaiqi ZHANG jie xiong Xiangdong LIU School of Economics and Commerce Guangdong University of Technology Department of Mathematics University of Macau Department of Mathematics Southern University of Science and Technology Department of Statistics Jinan University

In this article, we consider the partially observed optimal control problem for forward-backward stochastic systems with Markovian regime switching. A stochastic maximum principle for optimal control is developed using a variational method and filtering technique. Our theoretical results are applied to the motivating example of the risk minimization for portfolio selection.

关键词： partial information Markovian regime-switching stochastic maximum principle forwardbackward stochastic differential equation(FBSDE)

A zero-sum hybrid stochastic differential game with impulse controls

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第11期67卷 285-299页

作者： Siyu LV Zhen WU jie xiong School of Mathematics Southeast University School of Mathematics Shandong University Department of Mathematics and SUSTech International Center for Mathematics Southern University of Science and Technology

In this paper, we study a zero-sum stochastic differential game with the following salient features:(i) the system state is dictated by a hybrid diffusion,(ii) both players use impulse controls, and(iii) the game takes place on an infinite time horizon. First, the dynamic programming principle for the problem is ***, the lower and upper value functions of the game are characterized as the unique viscosity solution of the associated Hamilton-Jacobi-Bellman-Isaacs(HJBI) equation, which turns out to be a coupled system of variational inequalities with bilateral obstacles. Moreover, a verification theorem as a sufficient condition to identify a Nash equilibrium is established. The Nash equilibrium strategies for the two players, indicating when and how it is optimal to intervene, are given in terms of the obstacle part of the HJBI equation.

关键词： stochastic differential game Markov chain impulse control HJBI equation viscosity solution verification theorem

同方期刊数据库

Linear-quadratic stochastic Stackelberg differential game with asymmetric information

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第9期60卷 211-225页

作者： Jingtao SHI Guangchen WANG jie xiong School of Mathematics Shandong University School of Control Science and Engineering Shandong University Department of Mathematics University of Macau

This paper is concerned with a linear-quadratic stochastic Stackelberg differential game, where players have asymmetric roles, with one leader and one follower in the context of two-person game. It is required that the information available to the follower is a sub-σ-algebra of the one of the leader. By maximum principle and optimal filtering, a feedback Stackelberg equilibrium of the game is given. A special example is used to elaborate the result.

关键词： stochastic Stackelberg differential game linear-quadratic control asymmetric information condi tional mean-field forward-backward stochastic differential equation optimal filtering

UNIQUENESS PROBLEM FOR SPDES FROM POPULATION MODELS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2019年第3期39卷 845-856页

作者： jie xiong Xu YANG Department of Mathematicss Southern University of Science and TechnologyShenzhen 518055China School of Mathematics and Information Science North Minzu UniversityYinchuan 750021China

This is a survey on the strong uniqueness of the solutions to stochastic partial differential equations(SPDEs) related to two measure-valued processes: superprocess and Fleming-Viot process which are given as rescaling limits of population biology models. We summarize recent results for Konno-Shiga-Reimers’ and Mytnik’s SPDEs, and their related distribution-function-valued SPDEs.

关键词： Stochastic partial differential equation superprocess Fleming-Viot process distribution function backward doubly stochastic differential equation pathwise uniqueness

Linear-quadratic generalized Stackelberg games with jump-diffusion processes and related forward-backward stochastic differential equations

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2021年第9期64卷 2091-2116页

作者： Na Li jie xiong Zhiyong Yu School of Statistics Shandong University of Finance and EconomicsJinan250014China Department of Mathematics and SUSTech International Center for Mathematics Southern University of Science and TechnologyShenzhen518055China School of Mathematics Shandong UniversityJinan250100China

A kind of linear-quadratic Stackelberg games with the multilevel hierarchy driven by both Brownian motion and Poisson processes is *** Stackelberg equilibrium is presented by linear forward-backward stochastic differential equations(FBSDEs)with Poisson processes(FBSDEPs)in a closed *** the continuity method,the unique solvability of FBSDEPs with a multilevel self-similar domination-monotonicity structure is obtained.

关键词： Stackelberg game forward-backward stochastic differential equation stochastic optimal control linear-quadratic problem Poisson process

同方期刊数据库

Large deviation principle of occupation measures for non-linear monotone SPDEs

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2021年第4期64卷 799-822页

作者： Ran Wang jie xiong Lihu Xu School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Department of Mathematics and International Center for Mathematics Southern University of Science and TechnologyShenzhen 518055China Department of Mathematics Faculty of Science and TechnologyUniversity of MacaoMacaoChina

Using the hyper-exponential recurrence criterion,we establish the occupation measures’large deviation principle for a class of non-linear monotone stochastic partial differential equations(SPDEs)driven by Wiener noise,including the stochastic p-Laplace equation,the stochastic porous medium equation and the stochastic fast-diffusion *** also propose a framework for verifying hyper-exponential recurrence,and apply it to study the large deviation problems for strong dissipative *** SPDEs can be stochastic systems driven by heavy-tailedα-stable process.

关键词： stochastic partial differential equation large deviation principle occupation measure hyperexponential recurrence

Strength-toughness improvement of 13Cr4NiMo martensitic stainless steel with thermal cyclic heat treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第8期30卷 1499-1510页

作者： jie xiong Yao-lin Tong jie-long Peng Sheng-hua Zhang State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materialsand School of ResourcesEnvironment and MaterialsGuangxi UniversityNanning 530004GuangxiChina Key Laboratory of High Performance Structural Materials and Thermo-Surface Processing Education Department of Guangxi Zhuang Autonomous RegionGuangxi UniversityNanning 530004GuangxiChina

To improve the strength-toughness of 13Cr4NiMo martensitic stainless steel(13-4MSS),a thermal cyclic heat treatment(TCHT)combined with the advantage of tempering was *** microstructures were characterized by scanning electron microscopy,X-ray diffraction and electron backscattered diffraction,and the mechanical behaviors in terms of tensile properties and impact toughness were analyzed in correlation with microstructural *** was found that grains and the martensitic matrix were refined by TCHT through the cyclic quenching transformation and austenite recrystallization,which was conducive to more nucleation quantity of reversed austenite during ***-sphericalcap nucleation model was used to explain the effect of refined grains of TCHT on the nucleation of reversed *** refinement by TCHT improved the brittle fracture stress to reduce the ductile-brittle transition temperature and thus improved the cryogenic impact toughness of *** austenite distributed at the martensitic lath boundary enhances the crack arrest performance and increases the britle fracture *** is concluded that reasonable TCHT plus tempering process significantly improves the strength-toughness of 13-4MSS,reflecting the comprehensive effect of grain refinement and reversed austenite.

关键词： Strength-Toughness 13Cr4NiMo martensitic stainless steel Thermal cyclic heat treatment Grain refinement Reversed austenite