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Rare Metals 2021年第3期40卷 714-719页

作者： Yuan wang Xiu-chen Zhao Ying Liu yong wang Dong-Mei Li School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Center of Packaging and Testing Beijing Microelectronics Technology InstituteBeijing 100076China

The effects of adding small amounts of cerium(Ce) to Sn-3.3 Ag-0.2 Cu-4.7 Bi solder on microstructure,wettability characteristic,interfacial morphology and the growth of interfacial intermetallic compound(IMC) during thermal cycling were investigated by optical microscopy(OM),scanning electron microscopy(SEM) and solderability tester.It is found that the p-Sn phase,Ag_(3)Sn phase and Cu6 Sn5 phase in the solder are refined and the wetting force increases.Ce is an active element;it more easily accumulates at the solder/flux interface in the molten state,which decreases the interfacial surface energy and reduces the driving force for IMC formation on Cu substrate;therefore,the thickness of IMC at the solder/Cu interface decreases when appropriate Ce was added into the solder.Moreover,the Ce-containing solders have lower growth rate of interfacial IMC than solders without Ce during the thermal cycling between-55 and 125℃.When the Ce content is 0.03 wt% in the Sn-3.3 Ag-0.2 Cu-4.7 Bi solder,the solder has the best wettability and the minimum growth rate of interfacial IMC layer.

关键词： Lead-free solder Rare earth element Microstructure Wettability Intermetallic compound Thermal cycling

Research on the "three shells" cooperative support technology of large-section chambers in deep mines

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International Journal of Mining Science and Technology 2021年第4期31卷 665-680页

作者： cheng Zhu yong Yuan Wenmiao wang Zhongshun chen Shengzhi wang Huiwei Zhong Key Laboratory of Deep Coal Resources Mining Ministry of Education of ChinaChina University of Mining and TechnologyXuzhou 221116China School of Mines State Key Laboratory of Coal Resources&Safe MiningChina University of Mining and TechnologyXuzhou 221116China

The"three shells"cooperative support technology was proposed herein according to both the large deformation of the rock surrounding large-section chambers in deep mines and the precarious stability of the support structures therein.The development range of the plastic zone in the surrounding rock was controlled by a stress shell to reduce the difficulty of controlling the surrounding rock.Additionally,the residual strength of the rock mass in the plastic zone and the self-bearing capacity of the surrounding rock were improved by a reinforced load-bearing shell.Furthermore,a passive load-bearing shell could restore the triaxial stress state of the surrounding rock on the free surface,reduce the influence of the external environment on the surrounding rock,and reinforce the surrounding rock with the strength of the shell.Reasonable layouts of large-section chambers were determined by analyzing the control effect of the stress shell on the surrounding rock under three kinds of in situ stress fields.The orthogonal test method was applied to reveal the influences of different support parameters in the reinforced loadbearing shell and passive load-bearing shell on the surrounding rock stability.The surrounding rock control effect of the"three shells"collaborative support technology was analyzed through numerical simulation and field monitoring.The results show that the maximum displacement between the roof and floor of the coal preparation chamber in the Xinjulong coal mine was approximately 48 mm,and the maximum displacement between its two sides was approximately 65 mm,indicating that the technology proposed herein could meet the long-term control requirements of the surrounding rock stability for large-section chambers in deep mines.

关键词： Deep mining Large-section chamber "Three shells"cooperative support Reasonable layout Surrounding rock control

Quantification of TOC and TN in reservoir sediments using Fourier transform infrared spectroscopy

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Soil Ecology Letters 2022年第4期4卷 399-408页

作者： Lin Mei Yihong Yue yong Qin Xueping chen Fushun wang School of Environmental and Chemical Engineering Shanghai UniversityShanghai 200444China College of Food Sciences Xinyang Agriculture and Forestry UniversityXinyang 464000China

This study aims to quantitatively assess the total organic carbon(TOC)and total nitrogen(TN)content of reservoir sediments in southwest China using Fourier transform infrared spectroscopy(FTIRS).FTIRS measurements were performed on 187 sediment samples from four reservoirs to develop calibration models that relate FTIR spectral information with conventional property concentrations using partial least squares regression(PLSR).Robust calibration models were established for TOC and TN content.The external validation of these models yielded a significant correlation between FTIR-inferred and conventionally measured concentrations of R^(2)=0.88 for TOC,R^(2)=0.90 for TN.This method can be performed with a small sample size and is non-destructive throughout the simple measurement process.The TOC and TN content in the sediment can be determined with high effectiveness without being overly expensive,making it an advantageous method when measuring a large number of samples.

关键词： Fourier transform infrared spectroscopy Chemometrics Total organic carbon Total nitrogen Reservoir sediment

Critical scalarization and descalarization of black holes in a generalized scalar-tensor theory

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Science China(Physics,Mechanics & Astronomy) 2023年第10期66卷 44-52页

作者： Yunqi Liu cheng-yong Zhang Qian chen Zhoujian Cao Yu Tian Bin wang Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Department of Physics and Siyuan Laboratory Jinan UniversityGuangzhou 510632China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China Shanghai Frontier Science Center for Gravitational Wave Detection Shanghai Jiao Tong UniversityShanghai 200240China

We study the critical dynamics in scalarization and descalarization in the fully nonlinear dynamical evolution in the class of theories with a scalar field coupling with both Gauss-Bonnet(GB) invariant and Ricci scalar. We explore the manner in which the GB term triggers black hole(BH) scalarization. A typical type Ⅰ critical phenomenon is observed, in which an unstable critical solution emerges at the threshold and acts as an attractor in the dynamical scalarization. For the descalarization, we reveal that a marginally stable attractor exists at the threshold of the first-order phase transition in shedding off BH hair. This is a new type Ⅰ critical phenomenon in the BH phase transition. Implications of these findings are discussed from the perspective of thermodynamic properties and perturbations for static solutions. We examine the effect of scalar-Ricci coupling on the hyperbolicity in the fully nonlinear evolution and observe that such coupling can suppress the elliptic region and enlarge parameter space in computations.

关键词： black hole(de)scalarization dynamical critical behavior marginally attractor

Unraveling molecular-level mechanisms of reactive facet of carbon nitride single crystals photocatalyzing overall water splitting

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Rare Metals 2020年第12期39卷 1353-1355页

作者： Cong-yong wang chen-Huai Yang Zhi-cheng Zhang Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhou 350207China Department of Chemistry National University of SingaporeSingapore 117543Singapore Tianjin Key Laboratory of Molecular Optoelectronic Sciences Department of ChemistrySchool of ScienceTianjin University&Collaborative Innovation Center of Chemical Science and EngineeringTianjin 300072China

Despite the reactive facets play a vital role in designing highly efficient photocatalysts,it has long been a tremendous challenge to reveal the principle that reactive facets favor photocatalysis at the molecular lev... 详细信息

关键词： splitting catalysis designing

A plastic strain energy method exploration between machined surface integrity evolution and torsion fatigue behaviour of low alloy steel

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Chinese Journal of Aeronautics 2022年第10期35卷 412-429页

作者： yong wang Xibin wang Zhibing LIU Shuyao LIU Sitao wang Hongtao chen Ci SONG Yifan BAI Pai wang Yang LIU School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Fundamental Science for Advanced Machining Beijing Institute of TechnologyBeijing 100081China Beijing North Vehicle Group Corporation Beijing 100072China

To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low alloy steel for service performance,four multistage machining processes were applied to the 45Cr Ni Mo VA steel,including the Rough Turning process(RT),RT+the Finish Turning process(FRT),FRT+the Grinding process(GFRT)and RT+the Finish Turning process on dry cutting condition(FRT0).The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50%when it evolved from the RT process.The lower surface roughness of R1.3μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density,and the crack feature evolved from some specific bulges to flat shear plane characteristics.When the GFRT process evolved from the FRT process,its average fatigue life increased by 1.45 times,compared with the RT process.Plastic strain amplitude decreased by 21%,and the strain energy density decreased by 4%due to more considerable compressive residual stress(-249 MPa).Plastic deformation layer depth had a consistent tendency with surface roughness.In this paper,surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained.A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

关键词： Cyclic hysteresis loop Multistage machining processes Strain energy Surface integrity evolution Torsional fatigue

Aerodynamicmodeling using an end-to-end learning attitude dynamics network for flight control

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Acta Mechanica Sinica 2021年第12期37卷 1799-1811页

作者： Tun Zhao Gong chen Xiao wang Enmi yong Weiqi Qian The State Key Laboratory of Aerodynamics Mianyang Sichuan 621000China China Aerodynamics Research and Development Center Mianyang Sichuan 621000China

A novel identification method of aerodynamicmodels using a physics neural network,named the attitude dynamics network,which incorporates the attitude dynamics of an aircraft without any prior aerodynamic knowledge,is proposed.Then a learning controller,which combines feedback linearization with sliding mode control,is developed by introducing the learned aerodynamicmodels.The merit of the identification method is that the aerodynamicmodels can be learned end-to-end by the physics network directly from the flight data.Consequently,the paper uses an offline scheme and an online scheme to combine the identification process and the control process.In the offline scheme,learning the aerodynamic models and controlling the aircraft compose a cascade system,whereas the online scheme,similar to Learn-to-Fly,is a parallel system.Specifically,in the offline scheme,the physics neural network is trained by sufficient offline flight data,and then the trained network is substituted into the controller.The online scheme refers to the controller making the aircraft fly to generate flight data and sending these data to the deep network at the time of training,while the deep network provides the trained aerodynamic models to the controller at other times.Simulation results show that both under nominal and disturbance aerodynamic conditions,the network trained offline with a large amount of nominal data approximate the aerodynamicmodels well.Thus,the performance of the controller reaches a good level;for the online scheme,the predictive capability of the network increases and the performance of the controller improves with more training data.

关键词： Aerodynamic model identification Physics neural network Feedback linearization Sliding mode control Offline and online training

Experimental and numerical investigation on failure characteristics and mechanism of coal with different water contents

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International Journal of Coal Science & Technology 2023年第4期10卷 325-342页

作者： Xuewei Liu Haixiao chen Bin Liu Sai wang Quansheng Liu yong Luo Jin Luo State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Faculty of Engineering China University of GeosciencesWuhan 430074China Ping’an Mining Engineering Technology Research Institute Co. Ltd.Huainan 232001China

Water injection, as a widely used technique to prevent coal burst, can restrain the fractured coal seam and released the energy storage. In this study, laboratory tests were frstly carried out on standard coal specimens with fve diferent water contents (i.e., 0%, 0.6%, 1.08%, 1.5%, 2.0%, and 2.3%). The failure mode, fragment size, and energy distribution characteristics of coal specimens were investigated. Experimental results show that strength, elastic strain energy, dissipated energy, brittleness index, as well as impact energy index decrease with increasing water content. Besides, the failure mode transitions gradually from splitting ejection to tensile-shear mixed failure mode as water content increases, and average fragment size shows positively related to water content. Moreover, scanning electron microscope tests results indicate that water in coal sample mainly causes the mineral softening and defects increase. Furthermore, a numerical model containing roadway excavation was established considering the water on coal burst prevention. Modelling results revealed that water injection can reduce degree of coal burst and ejection velocity of coal blocks, while it will raise up the depth of crack zone and surface displacement of roadway. Combined with laboratory tests and numerical results, the micro mechanism, energy mechanism, and engineering signifcance of water injection on coal burst prevention were fnally analyzed.

关键词： Water content Coal burst Failure mode Energy Numerical simulation

Mainchain Semifluorinated Polymers with Ultra High Molecular Weight via Reaction-enhanced Reactivity of Intermediate(RERI) Mechanism

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Chinese Journal of Polymer Science 2023年第5期41卷 760-767,I0009页

作者： Jia-Sheng Wu wang-Meng Hou Zhi-Jia Liu Yi Shi yong-Ming chen School of Materials Science and Engineering Key Laboratory for Polymeric Composite and Functional Materials of Ministry of EducationSun Yat-Sen UniversityGuangzhou 510006China

Achieving the linear polymers with high molecular weight via step-growth polymerization of A2 and B2 monomers is significantly limited by the requirement of strict stoichiometry of two monomers when the reactivity of A and B groups are not changed during the polymerization.Herein,a unique step-growth polymerization based on copper-catalyzed azide-alkyne cycloaddition(CuAAC)with reactionenhanced reactivity of intermediate(RERI)mechanism was developed for the preparation of mainchain semifluorinated polymers with high molecular weight.The CuAAC polymerization of bis-alkynyl-terminated fluorinated monomers(A2)and 2,2-bis(azidomethyl)propane-1,3-diyl bis(2-methylpropanoate)(BiAz,B2)with RERI effect at different stoichiometric ratio was systematically investigated.The results indicated that the semifluorinated polymers with ultrahigh molecular weight,Mw,MALLS>106 g/mol,could be efficiently synthesized by using excess molar of BiAz monomers.The resultant high-molecular-weight semifluorinated polymers show good thermostability and high hydrophobicity.In addition,the glass transition temperature(Tg)of these mainchain semifluorinated polymers could be tuned conveniently due to the bis-alkynyl-terminated comonomers could be consumed completely when excessive BiAz monomers were used in this this step-growth polymerization.

关键词： Semifluorinated polymers Click polymerization Step-growth polymerization

Insights into influence of aging processes on zero-valent iron modified biochar in copper(II) immobilization: from batch solution to pilot-scale investigation

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Frontiers of Chemical Science and Engineering 2023年第7期17卷 880-892页

作者： Huabin wang Dingxiang chen Yi Wen Ting Cui Ying Liu yong Zhang Rui Xu School of Energy and Environment Science Yunnan Normal UniversityKunming 650500China Yunnan Key Laboratory of Rural Energy Engineering Kunming 650500China

The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization.However,these materials would be inevitably aged by natural forces after entering into the environment,while there are seldom studies reported the aging effects of zero-valent iron modified biochar.In this work,the hydrogen peroxide and hydrochloric acid solution were applied to simulate aging conditions of zero-valent iron modified biochar.According to the results,the adsorption capacity of copper(II)contaminants on biochar,zero-valent iron modified biochar-1,and zero-valent iron modified biochar-2 after aging was decreased by 15.36%,22.65%and 23.26%,respectively.The surface interactions were assigned with chemisorption occurred on multi-molecular layers,which were proved by the pseudo-second-order and Langmuir models.After aging,the decreasing of capacity could be mainly attributed to the inhibition of ion-exchange and zero-valent iron oxidation.Moreover,the plant growth and soil leaching experiments also proved the effects of aging treatment,the zero-valent iron modified biochar reduced the inhibition of copper(II)bioavailability and increased the mobility of copper(II)after aging.All these results bridged the gaps between bio-adsorbents customization and their environmental behaviors during practical agro-industrial application.

关键词： zero-valent iron modified biochar aging processes copper removal adsorption pilot-scale experiments