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Mechanism investigation on coal and gas outburst: An overview

International Journal of Minerals,Metallurgy and materials 2020年第7期27卷 872-887页

作者： yan-kun ma Bai-sheng Nie Xue-qiu He Xiang-chun Li Jun-qing Meng Da-zhao Song State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology(Beijing)Beijing 100083China Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources China University of Mining and Technology(Beijing)Beijing 100083China Xinjiang Institute of Engineering Urumqi 830023China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 10083China

Coal and gas outburst is a frequent dynamic disaster during underground coal mining *** about 150 years of exploration,the mechanisms of outbursts remain unclear to *** on outburst mechanisms worldwide focused on the physicochemical and mechanical properties of outburst-prone coal,laboratory-scale outburst experiments and numerical modeling,mine-site investigations,and doctrines of outburst *** mechanisms are divided into two categories:single-factor and multi-factor *** multi-factor mechanism is widely accepted,but all statistical phenomena during a single outburst cannot be explained using present *** topics about outburst mechanisms are proposed by summarizing the phenomena that need precise *** most appealing research is the microscopic process of the interaction between coal and *** physical-chemical methods can help characterize the natural properties of outburst-prone *** experiments can compensate for the deficiency of first-hand observation at the *** the original outburst scene by constructing a geomechanical model or numerical model and reproducing the entire outburst process based on mining environment conditions,including stratigraphic distribution,gas occurrence,and geological structure,are *** studies can explore outburst mechanisms at the microscale.

关键词： coal and gas outburst outburst mechanism outburst model outburst simulation microscopic pore structure

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Numerical simulation of fluid flow and free surface fluctuations during wheel and belt casting process

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Journal of Iron and Steel Research International 2024年第5期31卷 1117-1126页

作者： kun Gao yan Peng National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004HebeiChina

The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast *** lower level height tends to entrap inclusions in the molten *** the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was *** transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid *** results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the *** is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in *** jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged *** with the industrial observation and simulation results,the shape of the free surface is a wave that varies with *** addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.

关键词： Fluid flow Free surface Wheel and belt caster Large eddy simulation Volume of fluid method

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Thermal and mechanical behavior of casting copper alloy wheel during wheel and belt continuous casting process

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China Foundry 2024年第1期21卷 82-90页

作者： kun Gao yan Peng School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina

To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting *** effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in *** each rotation,the casting wheel passes through four different spray *** results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,*** temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.

关键词： casting wheel finite element model grinding thickness casting speed hot face spray zones

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Topology Optimization of Two Fluid Heat Transfer Problems for Heat Exchanger Design

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1949-1974页

作者： kun yan Yunyu Wang Jun yan School of Chemical Engineering Dalian University of TechnologyDalian116024China Jianghuai Advanced Technology Center Hefei230000China State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian116024China

Topology optimization of thermal-fluid coupling problems has received widespread *** article proposes a novel topology optimization method for laminar two-fluid heat exchanger *** proposed method utilizes an artificial density field to create two permeability interpolation functions that exhibit opposing trends,ensuring separation between the two fluid ***,a Gaussian function is employed to construct an interpolation function for the thermal conductivity ***,a computational program has been developed on the OpenFOAM platform for the topology optimization of two-fluid heat *** program leverages parallel computing,significantly reducing the time required for the topology optimization *** enhance computational speed and reduce the number of constraint conditions,we replaced the conventional pressure drop constraint condition in the optimization problem with a pressure inlet/outlet boundary *** 3D optimization results demonstrate the characteristic features of a surface structure,providing valuable guidance for designing heat exchangers that achieve high heat exchange efficiency while minimizing excessive pressure *** the same time,a new structure appears in large-scale topology optimization,which proves the effectiveness and stability of the topology optimization program written in this paper in large-scale calculation.

关键词： Topology optimization two fluid heat exchanger OpenFOAM large scale

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Human radiological safety assessment for petawatt laser-driven ion acceleration experiments in CLAPA-T

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matter and Radiation at Extremes 2024年第4期9卷 8-15页

作者： Xiaopeng Zhang Jiarui Zhao Shengxuan Xu Xun Chen Ying Gao Shiyou Chen kun Zhu Xueqing yan Wenjun ma State Key Laboratory of Nuclear Physics and Technology and Key Laboratory of HEDP of the Ministry of EducationCAPTPeking UniversityBeijing 100871China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsCASBeijing 100049China Beijing Laser Acceleration Innovation Center HuairouBeijing 101400China Institute of Guangdong Laser Plasma Technology BaiyunGuangzhou 510540China

The newly built Compact Laser Plasma Accelerator-Therapy facility at Peking University will deliver 60 J/1 Hz laser pulses with 30 fs *** by this petawatt laser facility,proton beams with energy up to 200 MeV are expected to be generated for tumor *** high-repetition operation,both prompt radiation and residual radiation may cause safety ***,human radiological safety assessment before commissioning is *** this paper,we simulate both prompt and residual radiation using the Geant4 and FLUKA Monte Carlo codes with reasonable proton and as-produced electron beam *** find that the prompt radiation can be shielded well by the concrete wall of the experimental hall,but the risk from residual radiation is nonnegligible and necessitates adequate radiation *** the basis of the simulation results,we discuss the constraints imposed by radiation safety considerations on the annual working time,and we propose radiation cooling strategies for different shooting modes.

关键词： laser prompt acceleration

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Mutual feedback between algal blooming and global warming

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Journal of Oceanology and Limnology 2024年第3期42卷 787-801页

作者： Jianrong ma Guijun yanG Xianfu ZHAO Boqiang QIN kun SHAN Botian ZHOU yan ZENG Jingfu WANG Jingan CHEN Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550002China School of Environment and Ecology Jiangnan UniversityWuxi 214122China Key Laboratory of Ministry of Water Resources for Ecological Impacts of Hydraulic-projects and Restoration of Aquatic Ecosystem Institute of HydroecologyMinistry of Water Resources&Chinese Academy of SciencesWuhan 430079China State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China

Global warming and algal blooms have been two of the most pressing problems faced by the world *** recent decades,numerous studies indicated that global warming promoted the expansion of algal ***,research on how algal blooms respond to global warming is *** warming coupled with eutrophication promoted the rapid growth of phytoplankton,which resulted in an expansion of algal *** blooms are affected by the combined effects of global warming,including increases in temperatures,CO_(2)concentration,and nutrient input to aquatic systems by extreme weather *** the growth of phytoplankton requires CO_(2),they appear to act as a carbon ***,algal blooms will release CH4,CO_(2),and inorganic nitrogen when they die and *** substrate nitrogen increases from decompose algal biomass,more N2O will be released by nitrification and *** comparison to CO_(2),CH4has 28-fold and N2O has 265-fold greenhouse ***,algal blooms in the polar regions may contribute to melting glaciers and sea ice(will release greenhouse gas,which contribute to global warming)by reducing surface albedo,which consequently would accelerate global ***,algal blooms and global warming could form feedback loops which prevent human survival and *** researches shall examine the mechanism,trend,strength,and control strategies involved in this mutual ***,it will promote global projects of environmental protection combining governance greenhouse gas emissions and algal blooms,to form a geoengineering for regulating the cycles of carbon,nitrogen,and phosphorus.

关键词： climate change carbon neutrality eutrophication greenhouse gas glaciers melting geoengineering

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Towards direct superlubricity and superlow wear via amino modification of polyhydroxy alcohol solutions

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Friction 2024年第9期12卷 1980-1990页

作者： Qiang ma Chengpeng yan Rui yan Xin XU Haifeng WANG State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China Chongqing Innovation Center Northwestern Polytechnical UniversityChongqing 401135China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China

Friction remains as the primary mode of energy dissipation and components wear,and achieving superlubricity shows high promise in energy conservation and lifetime wear *** results in this work demonstrate that direct superlubricity combined with superlow wear can be realized for steel/Si_(3)N_(4)contacts on engineering scale when polyhydroxy alcohol solution was selectively modified by amino *** direct superlubricity occurs because 3-amino-1,2-propanediol molecules at the friction interface could be induced to rotate and adsorb vertically on the friction surface,forming in-situ thick and dense molecular films to passivate the asperity ***,amino modification is also conducive to improving the lubrication state from boundary to mixed lubrication regime by strengthening the intermolecular hydrogen bonding interaction,presenting enhanced load-bearing capability and reduced direct solid asperity ***,direct superlow average friction of 0.01 combined with superlow wear are achieved *** design principle of direct superlubricity and superlow wear in this work indeed offers an effective strategy to fundamentally improve energy efficiency and provide lifetime wear protection for moving mechanical assemblies.

关键词： direct superlubricity amino modification molecular layer superlow wear

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Exploring the transformative impact of traditional Chinese medicine on depression:Insights from animal models

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World Journal of Psychiatry 2024年第5期14卷 607-623页

作者： yan yang yan-kun Chen Meng-Zhou Xie School of Nursing Hunan University of Chinese MedicineChangsha 410200Hunan ProvinceChina Precision Medicine R&D Center Zhuhai Institute of Advanced TechnologyChinese Academy of SciencesZhuhai 519000Guangdong ProvinceChina School of Chinese Medicine Hunan University of Chinese MedicineChangsha 410200Hunan ProvinceChina Hunan Engineering Technology Research Center for Medicinal and Functional Food Hunan University of Chinese MedicineChangsha 410200Hunan ProvinceChina Key Laboratory of TCM Heart and Lung Syndrome Differentiation and Medicated Diet and Dietotherapy Hunan University of Chinese MedicineChangsha 410200Hunan ProvinceChina

Depression,a prevalent and complex mental health condition,presents a significant global health *** is one of the most frequent mental disorders;deaths from it account for 14.3%of people *** recent years,the integration of complementary and alternative medicine,including traditional Chinese medicine(TCM),has gained attention as a potential avenue for addressing *** comprehensive review critically assesses the efficacy of TCM interventions in alleviating depressive *** in-depth look at different research studies,clinical trials,and meta-analyses is used in this review to look into how TCM practices like herbal formulations,acupuncture,and mindbody practices *** review looks at the quality of the evidence,the rigor of the methods,and any possible flaws in the current *** gives us an idea of where TCM stands right now in terms of treating *** comprehensive review aims to assess the efficacy of TCM interventions in alleviating depressive *** order to learn more about their possible healing effects,the study also looks into how different types of TCM work,such as herbal formulas,acupuncture,and mind-body practices.

关键词： Traditional Chinese medicine Depression Efficacy Treatment Holistic approach

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Atomic-scale mechanism of effect of co-separation of elements at interface of ferrite and austenite on Cr-depleted zone of duplex stainless steel

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Journal of Iron and Steel Research International 2024年第3期31卷 710-718页

作者： yan-hui Hou Ze-kun Xu Shi-long Zhou Guang-qiang Li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina

Three-dimensional atom-probe tomography and first-principles calculation combined with density functional theory were used to study the effect of the co-segregation of different elements formed during the solidification process of S32205 duplex stainless steel on the Cr-depleted zone at the interface between ferrite and *** was found that the co-segregation of different elements formed during the solidification process of duplex stainless steel can also form Cr-depleted zone at the interface between ferrite and ***,Mo,Si,B,C and P atoms promote co-segregation with Cr atoms,which promotes the formation of Cr-depleted zone at the interface between ferrite and austenite in duplex stainless *** and Si strongly promote the segregation of Cr at the interface between ferrite and austenite,thereby promoting the formation of Cr-depleted zone.B,C and P elements also promote the segregation of Cr element at the interface between ferrite and austenite and the formation of Cr-depleted zone,but their effect is weaker than that of Mo and Si *** conclusions provide a new theoretical basis for improving the intergranular corrosion performance of duplex stainless steel.

关键词： Duplex stainless steel Cr-depleted zone Intergranular corrosion Co-segregation First-principles calculation

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Six million Q factor micro fused silica shell resonator with teeth-like tines released by femtosecond laser-assisted chemical etching

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Science China(Technological Sciences) 2024年第6期67卷 1923-1932页

作者： ZHAO Tao SHI yan LU kun XI Xiang WU XueZhong XIAO DingBang College of Intelligence Science and Engineering National University of Defense TechnologyChangsha410073China

The quality factor(Q factor)is a crucial performance parameter for *** this paper,a novel release method for highquality micro fused silica shell resonators with teeth-like tines with good surface morphology is *** method is based on femtosecond laser-assisted chemical ***,the optimal energy range of femtosecond laser modification is obtained through mechanism ***,the optimal parameters for a straight line and arc pattern are determined by optimizing the average output power,processing speed,and processing *** results demonstrate why edge breakage in rounded corners is easy under different ***,according to these conclusions,the processing is performed on a micro fused silica shell resonator with a Q factor exceeding 6 *** addition,subsurface damage is rare throughout the fabrication process,and the surface roughness of the released cross section reaches the nanometer *** improved Q factor helps suppress mechanical thermal noise and reduce zero bias and zero bias drift,constituting the primary method for enhancing the performance of the resonant gyroscope.

关键词： micro hemispherical resonator fused silica laser-assisted chemical etching quality factor

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