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Changes in microstructure and properties of weld heat-affected zone of high-strength low-alloy steel

Journal of Iron and Steel Research International 2024年第8期31卷 2041-2052页

作者： Shu-jun Jia Qi-lin ma Yu Hou ba li He-song Zhang Qing-you liu Central Iron and Steel Research Institute Co. Ltd.Beijing 100081China Collaborative Innovation Center for Steel Commonality University of Science and Technology BeijingBeijing 100083China Construction Project management Branch of China National Petroleum Pipeline Network Group Co. Ltd.Langfang 065000HebeiChina

The evolution of the microstructure and toughness of APl5l X80 pipeline steel after thermal welding simulation was investigated by X-ray diffraction,electron backscatter diffraction,and transmission electron *** results indicated that primary heat-affected zones can be divided into weld,coarse-grained,fine-grained,intercritical,and sub-critical *** microstructure of the weld zone is mainly composed of bainitic ferrite and a small amount of granular bainite;however,the original austenite grains are distributed in the columnar *** structure of the coarse-grained zone is similar to that of the weld zone,but the original austenite grains are *** contrast,the microstructure in the fine-grained zone is dominated by fine granular bainite,and the effective grain size is only 8.15μm,thus providing the highest toughness in the entire heat-affected *** intercritical and subcritical zones were brittle valley regions,and the microstructure was dominated by granular ***,the martensite-austenite(M/A)constituents are present in island chains along the grain boundaries,and the coarse size of the M/A constituents seriously reduces the *** results of the crack propagation analyzes revealed that high-angle grain boundaries can significantly slow down crack growth and change the crack direction,thereby increasing the material *** impact toughness of the low-temperature tempering zone was equivalent to that of the columnar grain zone,and the impact toughness was between those of the critical and fine-grained zones.

关键词： Welding thermal simulation Impact toughness Crack propagation martensite-austenite constituent High-strength low-alloy steel weld Heat-affected zone

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Time-inconsistent stochastic linear-quadratic control problem with indefinite control weight costs

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Science China mathematics 2024年第1期67卷 211-236页

作者： Qi lü Bowen ma School of mathematics Sichuan UniversityChengdu 610064China

A time-inconsistent linear-quadratic optimal control problem for stochastic differential equations is *** introduce conditions where the control cost weighting matrix is possibly *** such conditions,we obtain a family of closed-loop equilibrium strategies via multi-person differential *** result extends Yong’s work(2017) in the case of stochastic differential equations,where a unique closed-loop equilibrium strategy can be derived under standard conditions(namely,the control cost weighting matrix is uniformly positive definite,and the other weighting coefficients are positive semidefinite).

关键词： linear-quadratic optimal control problem time-inconsistent cost functional generalized Riccati equation indefinite control weight cost closed-loop equilibrium strategy

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OptoGPT: A foundation model for inverse design in optical multilayer thin film structures

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Opto-Electronic Advances 2024年第7期7卷 4-16页

作者： Taigao ma Haozhu Wang l.Jay Guo Department of Physics University of MichiganAnn ArborMichigan 48109USA Department of Electrical Engineering and Computer Science University of MichiganAnn ArborMichigan 48109USA

Optical multilayer thin film structures have been widely used in numerous photonic ***,existing inverse design methods have many drawbacks because they either fail to quickly adapt to different design targets,or are difficult to suit for different types of structures,e.g.,designing for different materials at each *** methods also cannot accommodate versatile design situations under different angles and *** addition,how to benefit practical fabrications and manufacturing has not been extensively considered *** this work,we introduce OptoGPT(Opto Generative Pretrained Transformer),a decoder-only transformer,to solve all these drawbacks and issues simultaneously.

关键词： multilayer thin film structure inverse design foundation models deep learning structural color

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Guaranteed Cost Attitude Tracking Control for Uncertain Quadrotor Unmanned Aerial Vehicle Under Safety Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1447-1457页

作者： Qian ma Peng Jin Frank l.lewis School of Automation Nanjing University of Science and TechnologyNanjing 210094China UTA Research Institute University of Texas at ArlingtonFort WorthTexas 76118 USA IEEE

In this paper,guaranteed cost attitude tracking con-trol for uncertain quadrotor unmanned aerial vehicle(QUAV)under safety constraints is ***,an augmented system is constructed by the tracking error system and reference *** transformation aims to convert the tracking control prob-lem into a stabilization control ***,control barrier function and disturbance attenuation function are designed to characterize the violations of safety constraints and tolerance of uncertain disturbances,and they are incorporated into the reward function as penalty *** on the modified reward function,the problem is simplified as the optimal regulation problem of the nominal augmented system,and a new Hamilton-Jacobi-Bellman equation is ***,critic-only rein-forcement learning algorithm with a concurrent learning tech-nique is employed to solve the Hamilton-Jacobi-Bellman equa-tion and obtain the optimal *** proposed algorithm can not only ensure the reward function within an upper bound in the presence of uncertain disturbances,but also enforce safety *** performance of the algorithm is evaluated by the numerical simulation.

关键词： Attitude tracking control quadrotor unmanned aerial vehicle(QUAV) reinforcement learning safety constraints uncertain disturbances.

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Improved Reall-Santos method for AdS black holes in general 4-derivative gravities

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 74-86页

作者： Peng-Ju Hu liang ma Hong lü Yi Pang Center for Joint Quantum Studies and Department of Physics School of ScienceTianjin UniversityTianjin 300350China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhou 350207China Peng Huanwu Center for Fundamental Theory Hefei 230026China

For asymptotically flat black holes,Reall-Santos method is a convenient tool to compute leading higher derivative corrections to the thermodynamic quantities without actually solving the modified field ***,there are subtleties in its generalization to asymptotically AdS black holes with general higher derivative *** of all,it is necessary to know all the higher derivative holographic counterterms and the surface terms implementing the variational principle and subtracting the *** then needs to solve for the modified AdS radius and rescale the time coordinate in an appropriate way such that the induced metric on the conformal boundary of AdS black hole is not *** observe that Reall-Santos method can be directly applied to a particular 4-derivative gravity model,known as the Einstein-Weyl gravity,which does not modify the AdS radius and requires only the Gibbons-Hawking-York term and holographic counterterms for the 2-derivative *** thus suggest that to compute the thermodynamic quantities of AdS black holes in general 4-derivative theories of gravity,one simply needs to transform it to a Einstein-Weyl gravity with identical thermodynamic variables by appropriate field *** explicitly verify this proposal with spherically-symmetric and static charged black holes in Einstein-maxwell theory extended with generic 4-derivative interactions.

关键词： black holes thermodynamics higher-derivative corrections effective theories higher dimensional black holes quantum gravity

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Electrode particulate materials for advanced rechargeable batteries:A review

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Particuology 2024年第3期86卷 160-181页

作者： Mingyang ma Miao Du Yan liu Hongyan lü Jialin Yang Zelin Hao Jinzhi Guo Xinglong Wu MOE Key laboratory for UV light-Emitting materials and Technology Northeast Normal UniversityChangchunJilin130024China Department of Chemistry Northeast Normal UniversityChangchunJilin130024China

The demand for large-scale energy storage is increasing due to the decreasing non-renewable resources and deteriorating environmental *** rechargeable batteries with high energy density and long cycle performance is an ideal choice to meet the demand of energy storage *** development of excellent electrode particles is of great significance in the commercialization of nextgeneration *** ideal electrode particles should balance raw material reserves,electrochemical performance,price and environmental *** them,the development of electrode particulate materials with excellent electrochemical properties is the top priority at *** this review,the typical researches of electrode materials are summarized in terms of crystal structure,morphology,pore structure,surface and interface ***,the structural characteristics and improvement methods of transition metal oxides,polyanionic compounds,Prussian blue and their analogues are ***,the different effects of particulate morphology,pore,surface and interface structure on the performance of electrode materials are *** designing high-performance electrode materials,preparation route should be set according to the particle properties of the materials and the synergistic effect of various optimization methods should be *** the same time,in addition to the electrode materials,other components of the rechargeable batteries,such as current collector,separator and electrolytes,should be optimized to improve the overall performance of the *** review would provide important guiding principle for designing high-performance electrode particulate materials.

关键词： Particulate properties Electrode materials Rechargeable batteries

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The Influence of limestone Powder and Metakaolin Co-Blending on the Hydration Process and Mechanical Properties of Q-Phase Cement

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Journal of Wuhan University of Technology(materials Science) 2024年第5期39卷 1169-1176页

作者： XIONG Xuan HE Yongjia lÜlinnü ma Jie WANG Fazhou State Key laboratory of Silicate materials for Architectures Wuhan University of TechnologyWuhan 430070China School of materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Hubei Key laboratory of Theory and Application of Advanced materials Mechanics School of ScienceWuhan University of TechnologyWuhan 430070China China Railway Design Corporation Tianjin 300250China

A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated and compared with pure Q-phase *** results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40℃environment,significantly outperforming pure *** mechanism lies in that metakaolin effectively inhibits the transformation of metastable ***,the interactions among Q-phase,limestone,and metakaolin further enhance the cementitious *** ternary system effectively addresses potential issues of strength loss in Q-phase cement application,and as a low-carbon cementitious material system,it holds promising potential applications.

关键词： Q-phase limestone metakaolin hydration compressive strength

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Uniform decomposition of velocity gradient tensor

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Journal of Hydrodynamics 2024年第1期36卷 24-34页

作者： Chenxi ma Chaoqun liu Department of mathematics University of Texas at ArlingtonArlingtonTXUSA

In this paper,the principal decomposition of the velocity gradient tensor[∇v]is discussed in 3 cases based on the discriminant∆:∆0 with 3 distinct real eigen values,and∆=0 with 1 or 2 distinct real eigen *** velocity ... 详细信息

In this paper,the principal decomposition of the velocity gradient tensor[∇v]is discussed in 3 cases based on the discriminant∆:∆l eigen value and a pair of conjugate complex eigen values,∆>0 with 3 distinct real eigen values,and∆=0 with 1 or 2 distinct real eigen *** velocity gradient tensor can also be classified as rotation point,which can be decomposed into three parts,i.e.,rotation[R],shear[S]and stretching/compression[SC],and non-rotation point,we defined a new resistance term[l],and the tensor can be decomposed into three parts,i.e.,resistance[l],shear[S]and stretching/compression[SC].Example matric are also displayed to demonstrate the new *** of principal decomposition between 3 different cases,and between Resistance and liutex will also be discussed.

关键词： Velocity gradient liutex resistance fluid kinematics

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A combined liouville integrable hierarchy associated with a fourth-order matrix spectral problem

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Communications in Theoretical Physics 2024年第7期76卷 1-8页

作者： Wen-Xiu ma Department of mathematics Zhejiang Normal UniversityJinhua 321004China Department of mathematics King Abdulaziz UniversityJeddah 21589Saudi Arabia Department of mathematics and Statistics University of South Florida TampaFL 33620-5700United States of America material Science Innovation and Modelling Department of Mathematical SciencesNorth-West UniversityMafikeng CampusMmabatho 2735South Africa

This paper aims to propose a fourth-order matrix spectral problem involving four potentials and generate an associated liouville integrable hierarchy via the zero curvature formulation.A bi-Hamiltonian formulation is furnished by applying the trace identity and a recursion operator is explicitly worked out,which exhibits the liouville integrability of each model in the resulting *** specific examples,consisting of novel generalized combined nonlinear Schrodinger equations and modified Korteweg-de Vries equations,are given.

关键词： integrable hierarchy Hamiltonian structure zero curvature equation lax pair matrix spectral problem

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Two-Dimensional Metallophthalocyanine Nanomaterials for Electrocatalytic Energy Conversion

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Energy & Environmental materials 2024年第4期7卷 364-385页

作者： Xinqi Wang Shaohui Sun Jiahao Yao Hao Wan Renzhi ma Wei ma School of Chemical Engineering and Zhongyuan Critical Metals laboratory Zhengzhou University Research Center for materials Nanoarchitectonics (maNA) National Institute for Materials Science (NIMS)

Crowing energy demand drives the rapid development of clean and reliable energy *** the past years,the exploration of novel materials with considerable efficiency and durability has drawn attention in the area of elec... 详细信息

关键词： conjugated nanostructure electrocatalysis 2D metallophthalocyanines

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