TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Intergranular stress corrosion crack susceptibility of austenite stainless steel was evaluated through threepoint bending test conducted in high temperature water. The experimental results showed that the frequent and...Intergranular stress corrosion crack susceptibility of austenite stainless steel was evaluated through threepoint bending test conducted in high temperature water. The experimental results showed that the frequent and efficient introduction of low energy coincidence site lattice boundaries through grain boundary engineering resulted in an apparent improvement of the intergranular stress corrosion crack resistance of austenite stainless steel.展开更多
In recent years, a large number of geotechnical engineering projectshave been completed or under construction in China, such asthe Three Gorges Dam Project, Expressway Network Plan, South-to-North Water Diversion Proj...In recent years, a large number of geotechnical engineering projectshave been completed or under construction in China, such asthe Three Gorges Dam Project, Expressway Network Plan, South-to-North Water Diversion Project, West-to-East Gas Pipeline Project,etc. （Wang, 2003; Li, 2010; Huang, 2011; She and Lin, 2014）. Theconstruction of large-scale geotechnical engineering not onlybrings huge economic benefits, but also causes large interferenceto the lithosphere and hydrosphere that we rely on for survival（Wang et al., 2005）. This paper focuses on the interaction mechanismof rock engineering and geo-environments in the fields of urbanunderground space utilization, natural gas hydrate exploitationand high-level radioactive waste disposal.展开更多
Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachm...Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.展开更多
A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that th...A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.展开更多
Understanding the dynamic responses of hard rocks is crucial during deep mining and tunneling activities and when constructing nuclear waste repositories. However, the response of deep massive rocks with openings of d...Understanding the dynamic responses of hard rocks is crucial during deep mining and tunneling activities and when constructing nuclear waste repositories. However, the response of deep massive rocks with openings of different shapes and orientations to dynamic loading is not well understood. Therefore, this study investigates the dynamic responses of hard rocks of deep underground excavation activities. Split Hopkins Pressure Bar (SHPB) tests on granite with holes of different shapes (rectangle, circle, vertical ellipse (elliptical short (ES) axis parallel to the impact load direction), and horizontal ellipse (elliptical long (EL) axis parallel to the impact load direction)) were carried out. The influence of hole shape and location on the dynamic responses was analyzed to reveal the rocks' dynamic strengths and cracking characteristics. We used the ResNet18 (convolutional neural network-based) network to recognize crack types using high-speed photographs. Moreover, a prediction model for the stress-strain response of rocks with different openings was established using Deep Neural Network (DNN). The results show that the dynamic strengths of the granite with EL and ES holes are the highest and lowest, respectively. The strength-weakening coefficient decreases first and then increases with an increase of thickness-span ratio (h/L). The weakening of the granite with ES holes is the most obvious. The ResNet18 network can improve the analyzing efficiency of the cracking mechanism, and the trained model's recognition accuracy reaches 99%. Finally, the dynamic stress-strain prediction model can predict the complete stress-strain curve well, with an accuracy above 85%.展开更多
Owls exhibit remarkably silent flight,largely attributed to trailing-edge(TE)serrations on their wings.Inspired by this biological adaptation,TE serrations have become promising passive-noise-control strategies for ae...Owls exhibit remarkably silent flight,largely attributed to trailing-edge(TE)serrations on their wings.Inspired by this biological adaptation,TE serrations have become promising passive-noise-control strategies for aerodynamic devices,including drones and wind turbines.However,conventional designs typically feature single-scale geometries—Such as sawtooth or sinusoidal serrations—that fail to replicate the owl’s inherently dual-scale morphology:Macro-scale waviness formed by feather tips combined with micro-scale morphology.Here,we introduce and evaluate a hybrid TE serration design that incorporates both macro-scale wave patterns and micro-scale fringe-like elements to closely emulate the owl wing structure.Using large-eddy simulations coupled with the Ffowcs Williams-Hawkings acoustic analogy,we assess three configurations:A smooth baseline,a conventional wavy serration,and the proposed hybrid serration.Our results indicate that the hybrid configuration achieves an overall noise reduction of about 12 dB relative to the smooth baseline,surpassing the conventional wavy configuration by approximately 2.5 dB,while preserving aerodynamic performance as measured by lift-to-drag ratio.Flow-field analyses further reveal that dual-scale serrations effectively suppress TE pressure fluctuations,highlighting a key aeroacoustic advantage of the owl-inspired hybrid approach.These insights advance our understanding of bioinspired noisecontrol mechanisms and provide practical guidelines for designing quieter aerodynamic systems.展开更多
In this paper,a nonlinear control approach for an unstable networked plant in the presence of actuator and sensor limitations using robust right coprime factorization is proposed.The actuator is limited by upper and l...In this paper,a nonlinear control approach for an unstable networked plant in the presence of actuator and sensor limitations using robust right coprime factorization is proposed.The actuator is limited by upper and lower constraints and the sensor in the feedback loop is subjected to network-induced unknown time-varying delay and noise.With this nonlinear control method,we first employ right coprime factorization based on isomorphism and operator theory to factorize the plant,so that bounded input bounded output(BIBO)stability can be guaranteed.Next,continuous-time generalized predictive control(CGPC)is utilized for the unstable operator of the right coprime factorized plant to guarantee inner stability and enables the closed-loop dynamics of the system with predictive characteristics.Meanwhile,a second-Do F(degrees of freedom)switched controller that satisfies a perturbed Bezout identity and a robustness condition is designed.By using the CGPC controller that possesses predictive behavior and the second-Do F switched stabilizer,the overall stability of the plant subjected to actuator limitations is guaranteed.To address sensor limitations that exist in networked plants in the form of delay and noise which often cause system performance degradation,we implement an identity operator definition in the feedback loop to compensate for these adverse effects.Further,a pre-operator is designed to ensure that the plant output tracks the reference input.Finally,the effectiveness of the proposed design scheme is demonstrated by simulations.展开更多
Understanding the anchorage performance of en-echelon joints under cyclic shear loading is crucial for optimizing support strategies in jointed rock masses.This study examines the anchorage effects on enechelon joints...Understanding the anchorage performance of en-echelon joints under cyclic shear loading is crucial for optimizing support strategies in jointed rock masses.This study examines the anchorage effects on enechelon joints with various orientations using laboratory cyclic shear tests.By comparing unbolted and bolted en-echelon joints,we analyze shear zone damage,shear properties,dilatancy,energy absorption,and acoustic emission characteristics to evaluate anchoring effects across shear cycles and joint orientations.Results reveal that bolted en-echelon joints experience more severe shear zone damage after cycles,with bolt deformation correlating to shear zone width.Bolted en-echelon joints exhibit faster shear strength deterioration and higher cumulative strength loss compared to unbolted ones,with losses ranging from 20.04%to 72.76%.The compressibility of en-echelon joints reduces the anchoring effect during shear cycles,leading to lower shear strength of bolted en-echelon joints in later stages of shear cycles compared to unbolted ones.Bolts reinforce en-echelon joints more effectively at non-positive angles,with the best performance observed at 0°and-60°.Anchorage accelerates the transition from rolling friction to sliding friction in the shear zone,enhancing energy absorption,which is crucial for rock projects under dynamic shear loading.Additionally,rock bolts expedite the transition of the cumulative AE hits and cumulative AE energy curves from rapid to steady growth,indicating that strong bolt-rock interactions accelerate crack initiation,propagation,and energy release.展开更多
Limited models have been devised using Stern theory to obtain the repulsive force from a double layer.Moreover,an elastoplastic model that differentiates various swelling behaviors because of exchangeable cation speci...Limited models have been devised using Stern theory to obtain the repulsive force from a double layer.Moreover,an elastoplastic model that differentiates various swelling behaviors because of exchangeable cation species is yet to be devised.In this study,we introduce a novel multiphysics elastoplastic model for swelling geomaterials that incorporates Stern theory.This model considered the finite size of exchangeable cations and specific adsorption phenomena,which are typically overlooked in existing models.Based on Stern theory,we derived the repulsive force from the double layer and integrated the force into the elastoplastic expansive bedrock model,which addresses electroechemoemechanical phenomena in the interlayer.The proposed model differentiated swelling behaviors based on the type of exchangeable cation species by incorporating these phenomena.To validate the model,a onedimensional(1D)numerical analysis was performed,demonstrating its capability to describe various swelling behaviors due to different exchangeable cation species through comparison with free swelling test results of bentonite.Additionally,a parametric study was conducted to elucidate the effect of the hydrated radius of exchangeable cations and the specific adsorption potential on swelling behavior,analyzed from the perspective of the equilibrium of charge distribution near the mineral surface.展开更多
Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstructi...Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.展开更多
Professor Kazunari Domen at the Shinshu University and the University of Tokyo has pioneered materials and techniques for solar-driven water splitting using photocatalysts,a promising technology for contributing to th...Professor Kazunari Domen at the Shinshu University and the University of Tokyo has pioneered materials and techniques for solar-driven water splitting using photocatalysts,a promising technology for contributing to the construction of a sustainable and carbon-neutral society.In this paper,we summarize his groundbreaking contributions to photocatalytic water splitting and,more broadly,photocatalytic research.We highlight various novel functional photocatalytic materials,including oxides,(oxy)nitrides,and oxysulfides,along with innovative techniques such as cocatalyst engineering and Z-scheme system construction developed by the Domen Group.His team has also pioneered readily accessible and cost-effective photo(electro)chemical device fabrication methods,such as the particle-transfer method and thin-film-transfer method.Furthermore,their research has made significant contributions to understanding the(photo)catalytic mechanisms using advanced characterization techniques.Together with his research team,Professor Domen has set many milestones in the field of photocatalytic overall water splitting,notably demonstrating the first scalable and stable 100 m^(2)solar H_(2)production system using only water and sunlight.His work has revealed the potential for practical solar H2 production from water and sunlight,and highlighted the application of fundamental principles,combined with chemical and materials science tools,to design effective photocatalytic systems.Through this review,we focus on his research and the foundational design principles that can inspire the development of efficient photocatalytic systems for water splitting and solar fuel production.By building on his contributions,we anticipate a significant impact on addressing major global energy challenges.展开更多
The cutaneous ridges on dolphin skin have long been believed to effectively reduce friction drag, thereby contributing to overall drag reduction. However, since these skin ridges are oriented perpendicular to the swim...The cutaneous ridges on dolphin skin have long been believed to effectively reduce friction drag, thereby contributing to overall drag reduction. However, since these skin ridges are oriented perpendicular to the swimming direction, they also generate additional pressure drag, raising questions about the impact of the shape-induced pressure forces on swimming. Inspired by the microvibrations observed on dolphin skin, we hypothesize that the microstructure on dolphin skin is not static but dynamically oscillates in the form of Longitudinal Micro-Ultrasonic Waves (LMUWs). To explore this, we carried out a series of Computational Fluid Dynamics (CFD) simulations based on Large Eddy Simulation (LES) model to investigate the impact of pressure drag on the total drag acting on an oscillating skin surface under realistic turbulent flow conditions. The results indicate that the dynamic skin oscillations induce a new dynamic Stokes boundary layer, which has the potential to convert pressure drag into a negative force, thereby reducing total drag under the influence of traveling LMUW excitations. Furthermore, a relative velocity ξ, defined as the difference between the wave speed c and the external flow speed U, is introduced to evaluate the drag-reduction effect dominated by pressure. The findings reveal that pressure drag remains negative when ξ > 0. As ξ increases, the thrust effect induced by negative pressure becomes increasingly significant, ultimately counteracting friction drag and eliminating total drag. This pressure-dominated drag reduction mechanism thus demonstrates a novel strategy for the drag reduction technology and the potential of unveiling the mysteries behind dolphin swimming.展开更多
Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport o...Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.展开更多
Back stress has been proven to be the primary mechanism for superior mechanical properties of heterogeneous structures,but its quantitative contribution remains vague.The main purpose of this work is to clarify the co...Back stress has been proven to be the primary mechanism for superior mechanical properties of heterogeneous structures,but its quantitative contribution remains vague.The main purpose of this work is to clarify the contributions of back stress components,i.e.,intergranular residual stress and intragranular back stress,to the mechanical properties of heterogeneous structures based on the crystal plasticity theory.The results show that the intragranular back stress is smaller than the intergranular residual stress but contributes significantly to the strain hardening of the heterogeneous bimodal structures.In addition,the contributions of misorientation and grain size to back stress are quantitatively analyzed,and the near-linear relationship between hetero-deformation induced hardening and strain gradient is found.These findings emphasize the es-sential role of the intragranular back stress induced by strain gradient and provide an in-depth understanding of the elaborate roles of back stress in heterogeneous structures.展开更多
This study examines how ball milling parameters,specifically rotational speeds(20,40,and 60 r/min)in dry and wet condi-tions,affect the development of mullite/5wt%nano-fly ash coatings on AISI 410 steel,focusing on th...This study examines how ball milling parameters,specifically rotational speeds(20,40,and 60 r/min)in dry and wet condi-tions,affect the development of mullite/5wt%nano-fly ash coatings on AISI 410 steel,focusing on their impact on feedstock powders and plasma-sprayed coatings.Optimized milling parameters at 60 r/min under wet conditions yielded high-quality feedstock powders with a particle size of 14μm and limited size distribution.Coatings produced from wet-milled powders demonstrated a higher deposition effi-ciency(35%)due to their smaller,uniformly distributed particles,which enhanced melting during the spraying process.These coatings also exhibited significantly lower porosity(7.9%),resulting in denser structures with superior mechanical properties,including a hardness of HV_(1)647,fracture toughness of 1.41 MPa·m^(0.5),and a smoother surface finish with a roughness(R_(a))of 6.1μm.Residual stress analysis showed that wet-milled coatings had higher residual stresses,reaching up to 165.95 MPa,compared to dry-milled coatings.This increase is attributed to finer particle sizes and rapid thermal cycling during deposition,which intensified tensile stresses within the coating.These results highlight the importance of optimizing milling parameters to enhance coating performance and process efficiency.展开更多
We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight ma...We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight materials.First,the Mg/LPSO-extruded alloy shows greater elongation compared to other Mg solid-solution-extruded alloys when a certain high strength is required.Second,the simultaneous achievement of high strength and large elongation in the Mg/LPSO-extruded alloy enhances with a reduction in extrusion speed.In this study,the physical origins of these features were examined,focusing on how changes in the microstructure affect the mechanical properties of the extruded alloys.Our findings clarify that the LPSO phase contributes not only to increased strength but also to enhanced elongation through an increase in the work-hardening rate,a mechanism we termed aanisotropic mechanical property-induced ductilizationo(AMID).Until now,most efforts to improve the ductility of Mg materials have focused on achieving aisotropic mechanical propertieso via grain refinement.Based on our results,we propose an entirely opposite approach:increasing the elongation of Mg alloy by locally enhancing theiraanisotropic mechanical propertieso through the AMID mechanism.Computational analysis further suggests that reducing the diameter of Mg-worked grains should effectively improving elongation in Mg/LPSO alloys with a high volume fraction of Mg-worked grains.展开更多
Shock compression driven by nanosecond-laser techniques generates extreme pressure and temperature conditions in materials,enabling the study of high-pressure phase transitions and the behavior of materials in extreme...Shock compression driven by nanosecond-laser techniques generates extreme pressure and temperature conditions in materials,enabling the study of high-pressure phase transitions and the behavior of materials in extreme environments.These dynamic high-pressure states are relevant to a wide range of phenomena,including planetary formation,asteroid impacts,spacecraft shielding,and inertial confinement fusion.The integration of advanced X-ray diffraction experimental techniques,from laser-induced X-ray sources and X-ray free-electron lasers,and theoretical simulations has provided unprecedented insights into material behavior under extreme conditions.This perspective reviews recent advances in dynamic high-pressure research and the insights that they can provide,concentrating on dynamical phase transitions,metastable and transient states,the influence of crystal orientation,microstructural changes,and the kinetic mechanism of phase transitions across a variety of interdisciplinary fields.展开更多
Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in ...Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in irreversible changes and deterioration on its endurance.Numerous studies unveiled that hydrophobic surface protection could be an inexpensive and effective way of enhancing the durability of concrete.This research work aims to assess the feasibility of bio-cement posttreatment for facilitating hydrophobic surface protection,thus enhancing the performance and durability of concrete blocks.Enzyme induced carbonate precipitation(EICP)is one of the promising bio-cement methods.Concrete blocks casted in four different grades were subjected to EICP treatment with different treatment schemes and recipes of cementation media.The treated blocks were tested for water absorption,ultrasonic pulse velocity(UPV)measurements,unconfined compressive strength(UCS),thermal performance,and scanning electron microscopy(SEM).The results indicated that the concrete blocks subjected to EICP posttreatment showed over a 55%reduction in water absorption,a 15%higher UCS and a 6.7%higher UPV when compared with control blocks.The SEM analysis suggested that the EICP posttreatment could enhance the durability of concrete paving blocks by enabling a layer of calcite on the surface and by plugging the transport pore channels of the concrete.Although most of the posttreatment strategies investigated herein were found to be operative,a better response was seen in the posttreatment by spraying scheme with 0.5 mol/L cementation media(CM).With the successful demonstration,the EICP treatment prior to the use of concrete blocks can be recommended to the pavement construction industry.展开更多
Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipati...Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.展开更多
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
文摘Intergranular stress corrosion crack susceptibility of austenite stainless steel was evaluated through threepoint bending test conducted in high temperature water. The experimental results showed that the frequent and efficient introduction of low energy coincidence site lattice boundaries through grain boundary engineering resulted in an apparent improvement of the intergranular stress corrosion crack resistance of austenite stainless steel.
文摘In recent years, a large number of geotechnical engineering projectshave been completed or under construction in China, such asthe Three Gorges Dam Project, Expressway Network Plan, South-to-North Water Diversion Project, West-to-East Gas Pipeline Project,etc. （Wang, 2003; Li, 2010; Huang, 2011; She and Lin, 2014）. Theconstruction of large-scale geotechnical engineering not onlybrings huge economic benefits, but also causes large interferenceto the lithosphere and hydrosphere that we rely on for survival（Wang et al., 2005）. This paper focuses on the interaction mechanismof rock engineering and geo-environments in the fields of urbanunderground space utilization, natural gas hydrate exploitationand high-level radioactive waste disposal.
基金supported by MEXT KAKENHI Grant(24K01295,26286013).
文摘Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are commonly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and complex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solution-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(Ⅱ)iodide(SnI_(2))were mixed with lead halide(PbX_(2);X=I,Br)in the ligand solution.By precisely controlling the SnI_(2)concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabricated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China(Grant No.42172292)Taishan Scholars Project Special Funding,and Shandong Energy Group(Grant No.SNKJ 2022A01-R26).
文摘A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.
基金funding support from the National Natural Science Foundation of China(Grant No.52374119)the opening fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(Grant No.2011DA105827-FW202209)the opening fund of State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure,East China Jiaotong University(Grant No.HJGZ2023103).
文摘Understanding the dynamic responses of hard rocks is crucial during deep mining and tunneling activities and when constructing nuclear waste repositories. However, the response of deep massive rocks with openings of different shapes and orientations to dynamic loading is not well understood. Therefore, this study investigates the dynamic responses of hard rocks of deep underground excavation activities. Split Hopkins Pressure Bar (SHPB) tests on granite with holes of different shapes (rectangle, circle, vertical ellipse (elliptical short (ES) axis parallel to the impact load direction), and horizontal ellipse (elliptical long (EL) axis parallel to the impact load direction)) were carried out. The influence of hole shape and location on the dynamic responses was analyzed to reveal the rocks' dynamic strengths and cracking characteristics. We used the ResNet18 (convolutional neural network-based) network to recognize crack types using high-speed photographs. Moreover, a prediction model for the stress-strain response of rocks with different openings was established using Deep Neural Network (DNN). The results show that the dynamic strengths of the granite with EL and ES holes are the highest and lowest, respectively. The strength-weakening coefficient decreases first and then increases with an increase of thickness-span ratio (h/L). The weakening of the granite with ES holes is the most obvious. The ResNet18 network can improve the analyzing efficiency of the cracking mechanism, and the trained model's recognition accuracy reaches 99%. Finally, the dynamic stress-strain prediction model can predict the complete stress-strain curve well, with an accuracy above 85%.
基金supported by a Grant-in-Aid for Scientific Research of KAKENHI,Japan Society for the Promotion of Science(Grant Nos.23H01373 and 23K26068)support from the Japanese Government MEXT scholarship and the Excellent International Student Scholarship provided by Chiba University。
文摘Owls exhibit remarkably silent flight,largely attributed to trailing-edge(TE)serrations on their wings.Inspired by this biological adaptation,TE serrations have become promising passive-noise-control strategies for aerodynamic devices,including drones and wind turbines.However,conventional designs typically feature single-scale geometries—Such as sawtooth or sinusoidal serrations—that fail to replicate the owl’s inherently dual-scale morphology:Macro-scale waviness formed by feather tips combined with micro-scale morphology.Here,we introduce and evaluate a hybrid TE serration design that incorporates both macro-scale wave patterns and micro-scale fringe-like elements to closely emulate the owl wing structure.Using large-eddy simulations coupled with the Ffowcs Williams-Hawkings acoustic analogy,we assess three configurations:A smooth baseline,a conventional wavy serration,and the proposed hybrid serration.Our results indicate that the hybrid configuration achieves an overall noise reduction of about 12 dB relative to the smooth baseline,surpassing the conventional wavy configuration by approximately 2.5 dB,while preserving aerodynamic performance as measured by lift-to-drag ratio.Flow-field analyses further reveal that dual-scale serrations effectively suppress TE pressure fluctuations,highlighting a key aeroacoustic advantage of the owl-inspired hybrid approach.These insights advance our understanding of bioinspired noisecontrol mechanisms and provide practical guidelines for designing quieter aerodynamic systems.
文摘In this paper,a nonlinear control approach for an unstable networked plant in the presence of actuator and sensor limitations using robust right coprime factorization is proposed.The actuator is limited by upper and lower constraints and the sensor in the feedback loop is subjected to network-induced unknown time-varying delay and noise.With this nonlinear control method,we first employ right coprime factorization based on isomorphism and operator theory to factorize the plant,so that bounded input bounded output(BIBO)stability can be guaranteed.Next,continuous-time generalized predictive control(CGPC)is utilized for the unstable operator of the right coprime factorized plant to guarantee inner stability and enables the closed-loop dynamics of the system with predictive characteristics.Meanwhile,a second-Do F(degrees of freedom)switched controller that satisfies a perturbed Bezout identity and a robustness condition is designed.By using the CGPC controller that possesses predictive behavior and the second-Do F switched stabilizer,the overall stability of the plant subjected to actuator limitations is guaranteed.To address sensor limitations that exist in networked plants in the form of delay and noise which often cause system performance degradation,we implement an identity operator definition in the feedback loop to compensate for these adverse effects.Further,a pre-operator is designed to ensure that the plant output tracks the reference input.Finally,the effectiveness of the proposed design scheme is demonstrated by simulations.
基金financially supported by the National Natural Science Foundation of China (No.42172292)Taishan Scholars Project Special Funding,and Shandong Energy Group (No.SNKJ2022A01-R26)funded by the China Scholarship Council (CSC No.202006220274)。
文摘Understanding the anchorage performance of en-echelon joints under cyclic shear loading is crucial for optimizing support strategies in jointed rock masses.This study examines the anchorage effects on enechelon joints with various orientations using laboratory cyclic shear tests.By comparing unbolted and bolted en-echelon joints,we analyze shear zone damage,shear properties,dilatancy,energy absorption,and acoustic emission characteristics to evaluate anchoring effects across shear cycles and joint orientations.Results reveal that bolted en-echelon joints experience more severe shear zone damage after cycles,with bolt deformation correlating to shear zone width.Bolted en-echelon joints exhibit faster shear strength deterioration and higher cumulative strength loss compared to unbolted ones,with losses ranging from 20.04%to 72.76%.The compressibility of en-echelon joints reduces the anchoring effect during shear cycles,leading to lower shear strength of bolted en-echelon joints in later stages of shear cycles compared to unbolted ones.Bolts reinforce en-echelon joints more effectively at non-positive angles,with the best performance observed at 0°and-60°.Anchorage accelerates the transition from rolling friction to sliding friction in the shear zone,enhancing energy absorption,which is crucial for rock projects under dynamic shear loading.Additionally,rock bolts expedite the transition of the cumulative AE hits and cumulative AE energy curves from rapid to steady growth,indicating that strong bolt-rock interactions accelerate crack initiation,propagation,and energy release.
基金supported by the Japan Tunnelling Association and by JST SPRING(Grant Nos.JTA-R6-G1 and JPMJSP2114).
文摘Limited models have been devised using Stern theory to obtain the repulsive force from a double layer.Moreover,an elastoplastic model that differentiates various swelling behaviors because of exchangeable cation species is yet to be devised.In this study,we introduce a novel multiphysics elastoplastic model for swelling geomaterials that incorporates Stern theory.This model considered the finite size of exchangeable cations and specific adsorption phenomena,which are typically overlooked in existing models.Based on Stern theory,we derived the repulsive force from the double layer and integrated the force into the elastoplastic expansive bedrock model,which addresses electroechemoemechanical phenomena in the interlayer.The proposed model differentiated swelling behaviors based on the type of exchangeable cation species by incorporating these phenomena.To validate the model,a onedimensional(1D)numerical analysis was performed,demonstrating its capability to describe various swelling behaviors due to different exchangeable cation species through comparison with free swelling test results of bentonite.Additionally,a parametric study was conducted to elucidate the effect of the hydrated radius of exchangeable cations and the specific adsorption potential on swelling behavior,analyzed from the perspective of the equilibrium of charge distribution near the mineral surface.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFC2902103National Natural Science Foundation of China,Grant/Award Number:51934001Fundamental Research Funds for the Central Universities,Grant/Award Number:2023JCCXLJ02。
文摘Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.
基金supported by the Artificial Photosynthesis Project of the New Energy and Industrial Technology Development Organization(NEDO),the JST Fusion Oriented Research for disruptive Science and Technology Program(JPMJFR213D)JSPS KAKENHI(JP24K17774)Domen for his guidance during their PhD studies at the University of Tokyo,as well as for his ongoing support,encouragement,and mentorship.
文摘Professor Kazunari Domen at the Shinshu University and the University of Tokyo has pioneered materials and techniques for solar-driven water splitting using photocatalysts,a promising technology for contributing to the construction of a sustainable and carbon-neutral society.In this paper,we summarize his groundbreaking contributions to photocatalytic water splitting and,more broadly,photocatalytic research.We highlight various novel functional photocatalytic materials,including oxides,(oxy)nitrides,and oxysulfides,along with innovative techniques such as cocatalyst engineering and Z-scheme system construction developed by the Domen Group.His team has also pioneered readily accessible and cost-effective photo(electro)chemical device fabrication methods,such as the particle-transfer method and thin-film-transfer method.Furthermore,their research has made significant contributions to understanding the(photo)catalytic mechanisms using advanced characterization techniques.Together with his research team,Professor Domen has set many milestones in the field of photocatalytic overall water splitting,notably demonstrating the first scalable and stable 100 m^(2)solar H_(2)production system using only water and sunlight.His work has revealed the potential for practical solar H2 production from water and sunlight,and highlighted the application of fundamental principles,combined with chemical and materials science tools,to design effective photocatalytic systems.Through this review,we focus on his research and the foundational design principles that can inspire the development of efficient photocatalytic systems for water splitting and solar fuel production.By building on his contributions,we anticipate a significant impact on addressing major global energy challenges.
基金supported by the Japan Society for the Promotion of Science(JSPS KAKENHI No.23H01373).
文摘The cutaneous ridges on dolphin skin have long been believed to effectively reduce friction drag, thereby contributing to overall drag reduction. However, since these skin ridges are oriented perpendicular to the swimming direction, they also generate additional pressure drag, raising questions about the impact of the shape-induced pressure forces on swimming. Inspired by the microvibrations observed on dolphin skin, we hypothesize that the microstructure on dolphin skin is not static but dynamically oscillates in the form of Longitudinal Micro-Ultrasonic Waves (LMUWs). To explore this, we carried out a series of Computational Fluid Dynamics (CFD) simulations based on Large Eddy Simulation (LES) model to investigate the impact of pressure drag on the total drag acting on an oscillating skin surface under realistic turbulent flow conditions. The results indicate that the dynamic skin oscillations induce a new dynamic Stokes boundary layer, which has the potential to convert pressure drag into a negative force, thereby reducing total drag under the influence of traveling LMUW excitations. Furthermore, a relative velocity ξ, defined as the difference between the wave speed c and the external flow speed U, is introduced to evaluate the drag-reduction effect dominated by pressure. The findings reveal that pressure drag remains negative when ξ > 0. As ξ increases, the thrust effect induced by negative pressure becomes increasingly significant, ultimately counteracting friction drag and eliminating total drag. This pressure-dominated drag reduction mechanism thus demonstrates a novel strategy for the drag reduction technology and the potential of unveiling the mysteries behind dolphin swimming.
基金supported bythe Science and Technology Commission of Shanghai Municipality (Grant No.24CL2901702)The numerical calculations were performed at the Supercomputer Center (Project No.2024-Cb-0042)Institute for Solid State Physics,the University of Tokyo。
文摘Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.52222505,52321002,and 52005185)the Natural Science Foundation of Shanghai(Grant No.23ZR1415500)+2 种基金the China Scholarship Council(Grant No.202106740014)the Innovation Program of Shanghai Municipal Education Commission(Grant No.2019-01-07-00-02-E00068)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.YESS20200029).
文摘Back stress has been proven to be the primary mechanism for superior mechanical properties of heterogeneous structures,but its quantitative contribution remains vague.The main purpose of this work is to clarify the contributions of back stress components,i.e.,intergranular residual stress and intragranular back stress,to the mechanical properties of heterogeneous structures based on the crystal plasticity theory.The results show that the intragranular back stress is smaller than the intergranular residual stress but contributes significantly to the strain hardening of the heterogeneous bimodal structures.In addition,the contributions of misorientation and grain size to back stress are quantitatively analyzed,and the near-linear relationship between hetero-deformation induced hardening and strain gradient is found.These findings emphasize the es-sential role of the intragranular back stress induced by strain gradient and provide an in-depth understanding of the elaborate roles of back stress in heterogeneous structures.
基金financially supported by the King Mongkut’s University of Technology North Bangkok(KMUTNB),Thailand(No.KMUTNB-63-KNOW-039)the Electricity Generating Authority of Thailand(No.64-N201000-11-IO.SS03N3008589)the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(No.B13F660125).
文摘This study examines how ball milling parameters,specifically rotational speeds(20,40,and 60 r/min)in dry and wet condi-tions,affect the development of mullite/5wt%nano-fly ash coatings on AISI 410 steel,focusing on their impact on feedstock powders and plasma-sprayed coatings.Optimized milling parameters at 60 r/min under wet conditions yielded high-quality feedstock powders with a particle size of 14μm and limited size distribution.Coatings produced from wet-milled powders demonstrated a higher deposition effi-ciency(35%)due to their smaller,uniformly distributed particles,which enhanced melting during the spraying process.These coatings also exhibited significantly lower porosity(7.9%),resulting in denser structures with superior mechanical properties,including a hardness of HV_(1)647,fracture toughness of 1.41 MPa·m^(0.5),and a smoother surface finish with a roughness(R_(a))of 6.1μm.Residual stress analysis showed that wet-milled coatings had higher residual stresses,reaching up to 165.95 MPa,compared to dry-milled coatings.This increase is attributed to finer particle sizes and rapid thermal cycling during deposition,which intensified tensile stresses within the coating.These results highlight the importance of optimizing milling parameters to enhance coating performance and process efficiency.
基金supported by the Japan Science and Technology Agency(JST),CREST(grant number JPMJCR2094)。
文摘We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered(LPSO)phase,which are highly desirable for a new class of high-strength,lightweight materials.First,the Mg/LPSO-extruded alloy shows greater elongation compared to other Mg solid-solution-extruded alloys when a certain high strength is required.Second,the simultaneous achievement of high strength and large elongation in the Mg/LPSO-extruded alloy enhances with a reduction in extrusion speed.In this study,the physical origins of these features were examined,focusing on how changes in the microstructure affect the mechanical properties of the extruded alloys.Our findings clarify that the LPSO phase contributes not only to increased strength but also to enhanced elongation through an increase in the work-hardening rate,a mechanism we termed aanisotropic mechanical property-induced ductilizationo(AMID).Until now,most efforts to improve the ductility of Mg materials have focused on achieving aisotropic mechanical propertieso via grain refinement.Based on our results,we propose an entirely opposite approach:increasing the elongation of Mg alloy by locally enhancing theiraanisotropic mechanical propertieso through the AMID mechanism.Computational analysis further suggests that reducing the diameter of Mg-worked grains should effectively improving elongation in Mg/LPSO alloys with a high volume fraction of Mg-worked grains.
基金supported by the National Natural Science Foundation of China under Grant Nos.12534013,12035002,12047561,and 12104507as well as the Science and Technology Innovation Program of Hunan Province under Grant No.2021RC4026+1 种基金T.Sekine gratefully acknowledges financial support from the Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments,China(Grant No.22dz2260800)from the Shanghai Science and Technology Committee,China(Grant No.22JC1410300).
文摘Shock compression driven by nanosecond-laser techniques generates extreme pressure and temperature conditions in materials,enabling the study of high-pressure phase transitions and the behavior of materials in extreme environments.These dynamic high-pressure states are relevant to a wide range of phenomena,including planetary formation,asteroid impacts,spacecraft shielding,and inertial confinement fusion.The integration of advanced X-ray diffraction experimental techniques,from laser-induced X-ray sources and X-ray free-electron lasers,and theoretical simulations has provided unprecedented insights into material behavior under extreme conditions.This perspective reviews recent advances in dynamic high-pressure research and the insights that they can provide,concentrating on dynamical phase transitions,metastable and transient states,the influence of crystal orientation,microstructural changes,and the kinetic mechanism of phase transitions across a variety of interdisciplinary fields.
基金supported by the following two grants:(i)Japan Society for the Promotion of Science(JSPS)KAKENHI Grant Number JP22H01581(i)National Research Counsil(NRC)of Sri Lanka Investigator Driven Grant Number 22-041.
文摘Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in irreversible changes and deterioration on its endurance.Numerous studies unveiled that hydrophobic surface protection could be an inexpensive and effective way of enhancing the durability of concrete.This research work aims to assess the feasibility of bio-cement posttreatment for facilitating hydrophobic surface protection,thus enhancing the performance and durability of concrete blocks.Enzyme induced carbonate precipitation(EICP)is one of the promising bio-cement methods.Concrete blocks casted in four different grades were subjected to EICP treatment with different treatment schemes and recipes of cementation media.The treated blocks were tested for water absorption,ultrasonic pulse velocity(UPV)measurements,unconfined compressive strength(UCS),thermal performance,and scanning electron microscopy(SEM).The results indicated that the concrete blocks subjected to EICP posttreatment showed over a 55%reduction in water absorption,a 15%higher UCS and a 6.7%higher UPV when compared with control blocks.The SEM analysis suggested that the EICP posttreatment could enhance the durability of concrete paving blocks by enabling a layer of calcite on the surface and by plugging the transport pore channels of the concrete.Although most of the posttreatment strategies investigated herein were found to be operative,a better response was seen in the posttreatment by spraying scheme with 0.5 mol/L cementation media(CM).With the successful demonstration,the EICP treatment prior to the use of concrete blocks can be recommended to the pavement construction industry.
基金supported by the National Natural Science Foundation of China(Grant No.52109132)the Shandong Provincial Natural Science Foundation(Grant No.ZR2020QE270).
文摘Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.
