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Influence of blasting load directions on tunnel stability in fractured rock mass

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 346-365页

作者： Xiaohan Li Zheming Zhu Meng Wang Yun Shu Shuai Deng Dingjun Xiao key laboratory of Deep Underground Science and Engineering(ministry of education) College of Architecture and EnvironmentSichuan UniversityChengdu610065China Shock and Vibration of Engineering materials and Structures key laboratory of Sichuan Province Southwest University of Science and TechnologyMianyang621010China

Tunnels in fractured rock masses are typically damaged by dynamic disturbances from various directions.To investigate the influence of blasting load directions on the stability of a tunnel with a precrack nearby,blasting tests were conducted on the physical models of an external crack around a tunnel(ECT)in this study.Failure modes of the tunnels were analysed based on stress wave theory.The Riedel-Hiermaier-Thoma(RHT)material model was employed to perform the numerical simulations on ECT models.Stress distribution around the tunnels and final failure patterns of the tunnels were characterised.The results show that,under blasting loads,the pre-crack propagates and then new cracks initiates on the incident side of the tunnel.These cracks extend towards each other and eventually coalesce.Blasting load directions significantly influence the ultimate failure mode of the tunnel in the fractured rock masses.The new cracks on the shadow side of the tunnel appear at different positions when the blasting stress waves come from various directions.The results are meaningful to the analysis of tunnel stability and optimisation of the tunnel support scheme.

关键词： Blasting Tunnel stability Crack propagation Failure mode Numerical simulation

Grey Clustering Theory to Assess the Effect of Mineral Admixtures on the Cyclic Sulfate Resistance of Concrete

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Journal of Wuhan University of Technology(materials Science) 2010年第2期25卷 316-318页

作者：袁晓露李北星 key laboratory of Silicate materials Science and Engineering of ministry of education Wuhan University of Technology

Concrete specimens made with ordinary portland cement or ordinary portland cement incorporating fly ash with the replacement of 10% or 20%, ground blast furnace slag with the replacement of 15% or 30%, or 15% fly ash and 15% ground blast furnace slag were made and exposed to a cyclic sulfate environment. Concrete properties including relative dynamic elastic modulus, chloride ion diffusion coefficient, compressive strength and flexural strength were measured. Effect of mineral admixtures on the cyclic sulfate resistance of concrete was assessed based on the grey clustering theory. The experimental results indicate that the cyclic sulfate resistance of concrete incorporating ground blast furnace slag belongs to the higher grey grade, which exhibits that it possesses excellent cyclic sulfate resistance. With increasing addition of fly ash, the cyclic sulfate resistance of concrete changes from the medium grey grade to the lower grey grade, which shows that incorporation of fly ash is disadvantageous for the cyclic sulfate resistance of concrete.

关键词： cyclic sulfate resistance grey clustering theory mineral admixtures concrete

Light-induced dynamically tunable micropatterned surface for the regulation of the endothelial cell alignment

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Biosurface and Biotribology 2019年第2期5卷 46-51页

作者： Jiao Wang Chengzhen Chu Yang He Tao Xiang Shaobing Zhou key laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031People’s Republic of China

The surface topography has a great effect on the behaviour of adherent cells.We report an efficient method to prepare shape memory surfaces with dynamically changed micropatterns,which can be induced by near-infrared(NIR)light by varying the power density.After polydopamine(PDA)was coated on the cross-linked polyethylene glycol-poly(ɛ-caprolactone),the surface temperature increases by 40℃at room temperature when 808 nm light with 1.0 W/cm^(2)is used because of the photothermal properties of PDA.This temperature increase is enough for the shape recovery of the pressed micropatterns.The depth of the recovered micropatterns is controllable by adjusting the power density of the 808 nm light.The NIR-induced micropatterns efficiently regulate the morphology and alignment of endothelial cells.Therefore,NIR-induced shape memory surfaces have the potential to be used in remote-controlled devices.

关键词： alignment surface shape

Theoretical predication for transition energies of thermally activated delayed fluorescence molecules

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Chinese Chemical Letters 2016年第8期27卷 1445-1452页

作者： Xiaohui Tian Haitao Sun Qisheng Zhang Chihaya Adachi MOE key laboratory of Macromolecular Synthesis and functionalization Department of Polymer Science and Engineering Zhejiang University State key laboratory of Precision Spectroscopy School of Physics and Materials Science East China Normal University Center for Organic Photonics and Electronics Research (OPERA) Kyushu University

Thermally activated delayed fluorescence（TADF） emitters are primarily comprised of intramolecular charge-transfer（ICT） molecules with small energy difference between the lowest singlet and triplet excited states.They lend extremely favorable electroluminescent performance to organic light-emitting diodes（OLEDs）.This paper summarizes relevant issues and research efforts in the theoretical prediction of singlet- and triplet-transition energies of ICT molecules via time-dependent density functional theory（TDDFT）.The successful application of the descriptor-based optimal Hartree-Fock percentage method and the optimally tuned range-separated functional to many TADF systems represent an interesting approach to the exact prediction of the complex excited-state molecular dynamics within TDDFT.

关键词： Thermally activated delayed fluorescence Intramolecular charge-transfer Time-dependent density functional theory Transition Energy Descriptor

Nanoindentation response analysis of TiN-Cu coating deposited by magnetron sputtering

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Progress in Natural Science:materials International 2018年第1期28卷 40-44页

作者： Fuxing Ye Xu Sun School of materials Science & Engineering Tianjin University key laboratory of Advanced Ceramics and Machining Technology of ministry of education Tianjin University Tianjin key laboratory of Advanced Joining Technology Tianjin University

To investigate the change of the mechanical properties of soft metals doped PVD(Physical Vapor Deposition)coatings after the migration of soft metal to the surface, TiN-Cu coating was deposited on Si(100) by magnetron sputtering. The microstructure and mechanical properties at room temperature and after vacuum heat treatment at 300 ℃ were investigated. The results showed that the grains were clustered and the microstructure was porous for TiN-Cu coating at room temperature, while many micro-and nano-sized Cu particles were observed on the surface after vacuum heat treatment at 300 ℃. The elastic properties of the TiN-Cu coating after vacuum heat treatment at 300℃ degraded compared with that at room temperature. The hardness and elasticity modulus of TiN-Cu coating kept constant(3.7 GPa and 125.0 GPa, respectively) with the increase of nano-indentation depth, while the hardness and elasticity modulus of TiN-Cu coating after vacuum heat treatment at 300 ℃ increased gradually.

关键词： TiN-Cu coating Vacuum heat treatment Mechanical properties Nano-indentation depth

Phase-Field Simulation of Sintering Process:A Review

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1165-1204页

作者： Ming Xue Min Yi State key laboratory ofMechanics and Control forAerospace Structures&Institute for Frontier Science&key laboratory for Intelligent Nano materials and Devices of ministry of education&College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing210016China

Sintering,a well-established technique in powder metallurgy,plays a critical role in the processing of high melting point materials.A comprehensive understanding of structural changes during the sintering process is essential for effective product assessment.The phase-field method stands out for its unique ability to simulate these structural transformations.Despite its widespread application,there is a notable absence of literature reviews focused on its usage in sintering simulations.Therefore,this paper addresses this gap by reviewing the latest advancements in phase-field sintering models,covering approaches based on energy,grand potential,and entropy increase.The characteristics of various models are extensively discussed,with a specific emphasis on energy-based models incorporating considerations such as interface energy anisotropy,tensor-form diffusion mechanisms,and various forms of rigid particle motion during sintering.Furthermore,the paper offers a concise summary of phase-field sintering models that integrate with other physical fields,including stress/strain fields,viscous flow,temperature field,and external electric fields.In conclusion,the paper provides a succinct overview of the entire content and delineates potential avenues for future research.

关键词： Phase-field model review sintering additive manufacturing

In situ monitoring of Suzuki-Miyaura cross-coupling reaction by using surface-enhanced Raman spectroscopy on a bifunctional Au-Pd nanocoronal film

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Chinese Chemical Letters 2023年第4期34卷 449-452页

作者： Cancan Zhang Yonglong Li Aonan Zhu Ling Yang Xiaomeng Du Yanfang Hu Xian Yang Feng Zhang Wei Xie key laboratory of Advanced Energy materials Chemistry(ministry of education) Tianjin Key Lab of Molecular Recognition&BiosensingHaihe Laboratory of Sustainable Chemical TransformationsRenewable Energy Conversion and Storage CenterCollege of ChemistryNankai UniversityTianjin 300071China

Surface-enhanced Raman spectroscopy(SERS), a powerful surface vibrational spectroscopic technique, is ideally suited for in situ monitoring the chemical transformations occurred at surfaces and/or interfaces.For in situ SERS monitoring, a platform integrated both plasmonic and catalytic activity is a prerequisite. Here, we fabricate a bifunctional Au-Pd nanocoronal film for in situ SERS monitoring Suzuki-Miyaura cross-coupling reaction. This excellent bifunctional substrate leads to the coupling of high catalytic activity with a strong SERS effect at the center of two adjacent Au cores and shows fine reproducibility and stability of SERS signals. During investigating the Suzuki reaction with in situ SERS, we found two distinct catalytic kinetic processes resulted from two disparate catalytic sites on a Au-Pd nanocoronal. Comparing with conventional analytical techniques, this work provides a novel approach for studying Suzuki reactions at surfaces and/or interfaces with in situ SERS.

关键词： Suzuki-Miyaura cross-coupling reaction Au-Pd SERS In situ monitoring Kinetics

Holey graphene oxide-templated construction of nano nickel-based metal–organic framework for highly efficient asymmetric supercapacitor

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Nano Research 2022年第10期15卷 9047-9056页

作者： Hang Wang Pengfei Zhao Xingmao Zhang Su Zhang Xiaolong Lu Zhipeng Qiu Kang Ren Zheng Xu Ruxin Yao Tong Wei Zhuangjun Fan State key laboratory of Heavy Oil Processing School of Materials Science and EngineeringChina University of PetroleumQingdao 266580China key laboratory of Magnetic Molecules&Magnetic Information materials(ministry of education) Institute of Chemistry and CultureSchool of Chemistry&Material ScienceShanxi Normal UniversityTaiyuan 030006China

Metal–organic frameworks(MOFs)with redox-active metal sites and controllable crystalline structures make it possible to access the merits of highly-efficient electrode materials in electrochemical energy storage systems.However,most MOFs suffer from low capacitance and poor cycling stability that largely thwart their application.Herein,we present the holey graphene oxide(HGO)template strategy to prepare nano two-dimensional Ni(BDC)with HGO as both template and capping agent(denoted as Ni(BDC)-HGOx,x=10,20,30,and 40 according to the added HGO amount).Structural analyses reveal that HGO can significantly inhibit the Ni(BDC)agglomeration,thus offering a high ion-accessible surface area.Ni(BDC)-HGO30 with well-exposed active sites exhibits a high capacitance of 1,115.6 F·g^(−1) at 1 A·g^(−1) in 6 M KOH aqueous,1.8 times that of bulk Ni(BDC).An asymmetric supercapacitor with Ni(BDC)-HGO30 as a positive electrode and activated carbon as the opposing electrode delivers an energy density of 52.5 W·h·kg^(−1) and a power density up to 18.0 kW·kg−1,with 92.5%capacitance retention after 10,000 cycles.Galvanostatic intermittent titration technique and in situ electrochemical–Raman measurements were exploited to elucidate the electrochemical behavior of Ni(BDC)-HGO30.These results pave the way for the development of rationally tuned MOF materials for enhancing supercapacitor performances.

关键词： holey graphene oxide templated construction nano MOFs supercapacitor

Microstructure and Dynamic Compression Properties of PM Al6061/B_4C Composite

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Acta Metallurgica Sinica(English Letters) 2015年第10期28卷 1214-1221页

作者： Hong-Sheng Chen Wen-Xian Wang Hui-Hui Nie Yu-Li Li Qiao-Chu Wu Peng Zhang College of materials Science and Engineering Taiyuan University of Technology key laboratory of Interface Science and Engineering in Advanced materials Ministry of Education Taiyuan University of Technology Shanxi key laboratory of Advanced Magnesium-Based materials Taiyuan University of Technology

Aluminum 6061 matrix composite reinforced by 35 wt% B4 C particle was fabricated by power metallurgy method. Then, the as-deformed composite was tested by quasi-static（0.001 s-1） and dynamic（760-1150 s-1） compression experiments. The Johnson-Cook plasticity model was employed to model the flow behavior. The damage mechanism of composite was analyzed through the microstructure observations. The results showed that the B4 C particles exhibited uniform distribution and no deleterious reaction product Al4C3 was found in the composite. Al6061/B4 C composite showed high yield strength, moderate strain rate sensitivity and strain hardening under the dynamic loading, and a constitutive model under dynamic compression was established based on Johnson-Cook model, and accorded well with experimental results. The microstructure damage was dominated by particle fracture and interface debonding, and the dislocation was observed in the composite at a higher strain rate.

关键词： Power metallurgy Dynamic compression Johnson-Cook model AI6061/B4C composite