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International Journal of Minerals,Metallurgy and Materials 2021年第1期28卷 120-130页

作者： Xing-hai Yang Xiao-hua Chen Shi-wei Pan Zi-dong Wang Kai-xuan Chen Da-yong Li jun-wei qin School of Material Science and Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Two types of ultralow carbon steel weld metals(with and without added Cu-Nb) were prepared using gas metal arc welding(GMAW) to investigate the correlation between the microstructure and mechanical properties of weld *** results of microstructure characterization showed that the weld metal without Cu-Nb was mainly composed of acicular ferrite(AF), lath bainite(LB), and granular bainite(GB).In contrast, adding Cu-Nb to the weld metal caused an evident transformation of martensite and grain *** weld metals had a high tensile strength(more than 950 MPa) and more than 17% elongation;however, their values of toughness deviated greatly,with a difference of approximately 40 J at-50℃.Analysis of the morphologies of the fracture surfaces and secondary cracks further revealed the correlation between the microstructure and mechanical *** effects of adding Cu and Nb on the microstructure and mechanical properties of the weld metal are discussed;the indication is that adding Cu-Nb increases the hardenability and grain size of the weld metal and thus deteriorates the toughness.

关键词： weld metal microstructure mechanical properties hardenability grain coarsening

Experimental analysis of matrix moveable oil saturation in tight sandstone reservoirs of the south Ordos Basin,China

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Energy Geoscience 2024年第1期5卷 184-195页

作者： Ting Xu jun Pu Xuejie qin Yi wei Science and Technology Development Department Petroleum Exploration&Production Research InstituteSINOPECBeijing100083China Center Research Department of North China Petroleum Exploration&Production Research Institute SINOPECBeijing100083China Oil Field Development Department Petroleum Exploration&Production Research InstituteSINOPECBeijing100083China

Tight oil reservoirs in the south Ordos Basin are characterized by fractured,heterogeneous oil-bearing strata(an oil saturation of less than 55%on average),normal pressure(0.8±)and extra-low permeability(less than 0.3 mD).In the Chang 8 tight sandstone reservoir in Honghe oilfield,micro-and nanopores,especially those with a pore-throat radius of less than 1 mm,account for more than 90%.Fluid flow in the matrix is non-linear and crude oil flow rates are very low under normal pressure *** improved understanding of oil mobility in a tight matrix is key to further development of normalpressure tight-oil resources in the continental *** this study,constant-velocity and high-pressure mercury injection experiments were conducted using samples of typical tight sandstone cores obtained from the south of Ordos Basin.A new method for reconstructing the full-scale pore-throat distribution characteristics of tight sandstone reservoirs was established successfully,based on which multistage centrifugal tests,tests of low-pressure differential displacement of oil by water,and nuclear magnetic resonance tests were conducted in order to obtain the distribution characteristics of moveable fluid in different *** moveable oil saturation(MOS)and degree of oil recovery(*** of accumulative oil production to producing geologic reserves)of the core samples under different differential pressures for displacement were *** for the tight oil reservoirs in the south Ordos Basin,the moveable fluids are mainly stored in sub-micron(0.10-0.5 mm)*** Type I reservoirs(k>0.1 mD),the volume percentage of moveable fluid in pores with a radius larger than 0.5 mm is relatively high(greater than 40%).The degree of oil recovery of water flooding serves as the basis for forecasting recoverable reserves for tight oil *** reserves under water flooding,mainly occur in pores with a radius greater than 0.5 *** contribution of Type I reserves to oil pro

关键词： Tight reservoir Pore-throat structure Moveable fluid volume Moveable oil saturation(MOS) Waterflooding oil recovery South Ordos basin

Maternal weight and its association with risk of overweight in offspring:a trajectory analysis from a birth cohort in China

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World Journal of Pediatrics 2024年第5期20卷 496-505页

作者： Rui Deng wei-qin Li Xing-Xiu Li Liu-Mei wei Jie Hu jun-Hong Leng Bin Dong Institute of Child and Adolescent Health School of Public HealthPeking University Health Science CenterNo.38 Xueyuan RdHaidian DistrictBeijing100191China Tianjin Women and Children’s Health Center No.96 Guizhou RdHeping DistrictTianjin300070China Menzies Health Institute Queensland Griffith UniversityNathanQLD4111Australia

Background Most studies on the association of maternal pregnancy weight with offspring weight trajectory have a short follow-up *** study aimed to explore the associations of maternal prepregnancy body mass index(BMI)and gestational weight gain(GWG)with childhood weight trajectories in a 7-year birth *** A total of 946 mother–child pairs(467 boys and 479 girls)from a longitudinal birth cohort in Tianjin City,China,were included in this study,ranging from pregnancy to offspring at 7 *** outcome variable was defined as overweight or not overweight in offspring at the last round.A group-based trajectory model was applied to identify childhood BMI trajectory *** Five discrete BMI trajectory groups were identified and characterized as constant underweight(25.2%),constant normal weight(42.8%),and high or increasing trajectory[at risk of overweight(16.9%),progressive overweight(11.0%)and progressive obesity(4.1%)].Maternal prepregnancy overweight was associated with 1.72(95%CI 1.14–2.60,P=0.01)to 4.02(95%CI 1.94–8.36,Pweight[relative risk ratio(RRR)2.09,95%CI 1.27–3.46,P=0.004]and progressive obesity(RRR 3.33,95%CI 1.13–9.79,P=0.029).Children in all high or increasing trajectory groups were associated with greater overweight risk at the last round[risk ratios(RRs)ranged from 3.54(95%CI 2.53–4.95,Pweight and excessive gestational weight gain were associated with increasing or high-level childhood body mass index trajectories as well as a greater risk of overweight at 7 years.

关键词： Body-weight trajectory Child Gestational weight gain Overweight Pregnancy

Control of chiral-optical activities by magnetic field based on the transformation of achiral binary crystals into chiral ternary crystals

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Science China Chemistry 2024年第7期67卷 2300-2305页

作者： Zhiyan Chen Yan Lv wei qin College of Physics Qingdao UniversityQingdao 266071China School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China Shandong Linuo Photovoltaic Hi-Tech Co. Ltd.Jinan 250100China

Multicomponent self-assembled chiral systems have attracted great attention due to their promising application in the area of spin-photonics and *** this work,through introducing an achiral third component into an achiral binary crystal,a chiral organic ternary crystal is fabricated,where both pronounced chiral-optical coupling and magnetic field dependence of chiral-optical activities are *** transformation of achiral structure into chiral structure generates a significant effect on the polarized state of light and the electron spin resonance ***,the coupling between circularly polarized photon and spin is observed in chiral ternary crystal with pronounced chiral orbit,where obvious magnetic field-transmissivity loop is ***,temperature could increase the magnitude of lattice parameters to lead to a larger helix radius to increase the chiral orbit ***,this work indicates that the further exploration of photon-chiral orbit-spin interactions in organic chiral ternary crystals is promising.

关键词： organic chiral ternary crystals chiral orbit chiral-optical activities magnetic field

Learning in games:a systematic review

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Science China(Information Sciences) 2024年第7期67卷 133-159页

作者： Rong-jun qin Yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir Technologies

Game theory studies the mathematical models for self-interested individuals. Nash equilibrium is arguably the most central solution in game theory. While finding the Nash equilibrium in general is known as polynomial parity arguments on directed graphs(PPAD)-complete, learning in games provides an alternative to approximate Nash equilibrium, which iteratively updates the player's strategy through interactions with other players. Rules and models have been developed for learning in games, such as fictitious play and no-regret learning. Particularly, with recent advances in online learning and deep reinforcement learning,techniques from these fields greatly boost the breakthroughs in learning in games from theory to *** a result, we have witnessed many superhuman game AI systems. The techniques used in these systems evolve from conventional search and learning to purely reinforcement learning(RL)-style learning methods,gradually getting rid of the domain knowledge. In this article, we systematically review the above techniques,discuss the trend of basic learning rules towards a unified framework, and recap applications in large ***, we discuss some future directions and make the prospect of future game AI systems. We hope this article will give some insights into designing novel approaches.

关键词： non-cooperative games learning in games no-regret learning reinforcement learning superhuman AI

Hydraulic fracturing behaviors of shale under coupled stress and temperature conditions simulating different burial depths

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International Journal of Mining Science and Technology 2024年第6期34卷 783-797页

作者： qin Zhou Zheming Zhu wei Liu Huijun Lu Zidong Fan Xiaofang Nie Cunbao Li jun Wang Li Ren MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Downhole Operating Company CNPC Chuanqing Drilling and Exploration Engineering Co.Ltd.Shenzhen 518060China School of Architecture and Civil Engineering Xihua UniversityChengdu 610065China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Shenzhen UniversityShenzhen 518060China

Fracture propagation in shale under in situ conditions is a critical but poorly understood mechanical process in hydraulic fracturing for deep shale gas reservoirs. To address this, hydraulic fracturing experiments were conducted on hollow double-wing crack specimens of the Longmaxi shale under conditions simulating the ground surface(confining pressure σ_(cp)=0, room temperature(Tr)) and at depths of 1600 m(σ_(cp)=40 MPa, Ti=70 ℃) and 3300 m(σ_(cp)=80 MPa, high temperature Ti=110 ℃) in the study *** in situ stress was found to significantly increase fracture toughness through constrained microcracking and particle frictional bridging mechanisms. Increasing the temperature enhances rather than weakens the fracture resistance because it increases the grain debonding length, which dissipates more plastic energy and enlarges grains to close microdefects and generate compressive stress to inhibit microcracking. Interestingly, the fracture toughness anisotropy in the shale was found to be nearly constant across burial depths, despite reported variations with increasing confining pressure. Heated water was not found to be as important as the in situ environment in influencing shale fracture. These findings emphasize the need to test the fracture toughness of deep shales under coupled in situ stress and temperature conditions rather than focusing on either in situ stress or temperature alone.

关键词： Hydraulic fracturing Fracture toughness Shale Anisotropy Deep rock mechanics

C-CORE:Clustering by Code Representation to Prioritize Test Cases in Compiler Testing

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2069-2093页

作者： wei Zhou Xincong Jiang Chuan qin School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai200240China Hikvision Research Institute Hangzhou Hikvision Digital Technology Co.Ltd.Hangzhou310051China

Edge devices,due to their limited computational and storage resources,often require the use of compilers for program ***,ensuring the security and reliability of these compilers is of paramount importance in the emerging field of edge *** widely used testing method for this purpose is fuzz testing,which detects bugs by inputting random test cases into the target ***,this process consumes significant time and *** improve the efficiency of compiler fuzz testing,it is common practice to utilize test case prioritization *** researchers use machine learning to predict the code coverage of test cases,aiming to maximize the test capability for the target compiler by increasing the overall predicted coverage of the test ***,these methods can only forecast the code coverage of the compiler at a specific optimization level,potentially missing many optimization-related *** this paper,we introduce C-CORE(short for Clustering by Code Representation),the first framework to prioritize test cases according to their code representations,which are derived directly from the source *** approach avoids being limited to specific compiler states and extends to a broader range of compiler ***,we first train a scaled pre-trained programming language model to capture as many common features as possible from the test cases generated by a *** this pre-trained model,we then train two downstream models:one for predicting the likelihood of triggering a bug and another for identifying code representations associated with ***,we cluster the test cases according to their code representations and select the highest-scoring test case from each cluster as the high-quality test *** reduction in redundant testing cases leads to time *** evaluation results reveal that code representations are better at distinguishing test capabilities,and C-CORE significantly enhanc

关键词： Compiler testing test case prioritization code representation

Magnetocaloric effect and phase transition critical behavior of La0.75Sr0.25Mn0.9Co0.1O3 compound synthesized under the high pressure

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Tungsten 2024年第03期6卷 621-632页

作者： Jing Zhao Lei Gao Jian-jun Zhao wei wei Hui-qin Yun Ru Xing Huai-Jin Ma Xiang Jin Luo-Meng Chao School of Physical Science and Technology Key Laboratory of Magnetism and Magnetic Materials for Higher Education in Inner Mongolia Autonomous Region Baotou Teachers' College National Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization Baotou Research Institute of Rare Earths School of Physics and Electronic Information Inner Mongolia Normal University College of Science Inner Mongolia University of Science and Technology

In this study,a novel method is proposed for producing perovskite rare-earth manganese oxide magnetic refrigeration materials that exhibit superior properties compared to similar *** maximum magnetic entropy change values for this sample are 1.44 and 3.75 J·kg-1·K-1for magnetic fields of 2 and 7 T,***,its relative cooling power has been calculated to be 101.96 and 404.78 J·kg-1,indicating good *** results were obtained using the sample synthesized under a pressure of 4 GPa,and the sample has undergone a second phase *** critical behavior of the sample fits well with the mean field *** different magnetic fields,there is a significant overlap between the values of the maximum magnetic entropy change and the temperature-averaged entropy change,indicating that the refrigeration performance of the sample after high pressure can approach its maximum capability.

关键词： High-pressure synthesis Magnetocaloric effect Relative cooling power Magnetic phase transition

Carbon-based materials with combined functions of thermal management and electromagnetic protection: Preparation, mechanisms, properties, and applications

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Nano Research 2024年第3期17卷 883-903页

作者： junwei Yue Yiyu Feng Mengmeng qin wei Feng School of Materials Science and Engineering and Tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin 300350China

The proliferation of high-power,highly informationized,and highly integrated electronic devices and weapons equipment has given rise to increasingly conspicuous issues about electromagnetic(EM)pollution and thermal *** issues,in turn,impose constraints on the performance of such equipment and jeopardize personnel *** materials,owing to their diverse and modifiable structures,offer adjustable thermal and electric conductivity,rendering them highly promising for applications in fields such as thermal management and EM protection which have garnered extensive research and *** pursuit of integrated device and equipment development has elevated the demand for multifunctional materials,prompting significant research into carbon-based composite materials that include both thermal management and EM protection ***,there are no relevant reviews on this topic at ***,this work consolidates research findings from recent years on carbon matrix composites exhibiting dual attributes of thermal management and EM *** attributes include thermally conductive electromagnetic interference(EMI)shielding materials,thermally insulating EMI shielding materials,thermally conductive EM wave(EMW)absorbing materials,and thermally insulating EMW absorbing *** paper elucidates the fundamental principles underpinning thermal conduction,thermal insulation,EMW absorbing,and EMI ***,it engages in discussions surrounding areas of contention,design strategies,and the functional properties of various material ***,the paper concludes by presenting the challenges encountered and potential research strategies about composites endowed with both thermal management and EM protection functionalities,while also envisaging the development of novel multifunctional EM protection materials.

关键词： carbon-based composites electromagnetic interference shielding microwave absorption thermal conduction thermal insulation

Transient state analysis of a rub-impact rotor system during maneuvering flight

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Chinese Journal of Aeronautics 2024年第7期37卷 236-251页

作者： jun WANG Yunfei LIU Zhaoye qin Liang MA Fulei CHU Beijing Key Laboratory of Health Monitoring and Self-Recovery for High-End Machinery Equipment Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China

Maneuvering flight substantially affects the dynamic behavior of rotors;particularly,such flight may cause rubbing between a rotor and stator,which is one of the most serious damages in aircraft *** this paper,a nonlinear dynamic model for describing the dynamic characteristics of a rub-impact rotor system during maneuvering flight is established based on the Lagrange ***,numerical simulations employing the Newmark method are performed,delving into the detailed discussion of the influence of parameters such as rotational speed and maneuvering flight on the transient and steady-state responses of the rotor *** effect mechanism of maneuver load and its coupling with rub impact is *** results show that the impact response induced by maneuvering flight is more obvious in the subcritical state than in the supercritical *** additional stiffness and damping are also induced;in particular,the additional damping has a coupling ***,the rub impact imposes an additional constraint on the rotor system,thereby weakening the influence of the maneuver load and becoming the major factor that determines the dynamic behavior of the rotor system at high speeds.

关键词： Maneuvering flight Rub impact Rotor system Dynamic response Impact response