Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force ...Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.展开更多
Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,an...Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,and defects behind the structure.To address the need for rapid detection of different defect types,the current state of rapid detection technologies and equipment,both domestically and internationally,is systematically reviewed.The research reveals that surface defect detection technologies and equipment have developed rapidly in recent years.Notably,the integration of machine vision and laser scanning technologies have significantly improved detection efficiency and accuracy,achieving crack detection precision of up to 0.1 mm.However,the non-contact rapid detection of internal and behind-the-structure defects remains constrained by hardware limitations,with traditional detection remaining dominant.Nevertheless,phased array radar,ultrasonic,and acoustic vibration detection technologies have become research hotspots in recent years,offering promising directions for detecting these challenging defect types.Additionally,the application of multisensor fusion technology in rapid detection equipment has further enhanced detection capabilities.Devices such as cameras,3D laser scanners,infrared thermal imagers,and radar demonstrate significant advantages in rapid detection.Future research in tunnel inspection should prioritize breakthroughs in rapid detection technologies for internal and behind-the-structure defects.Efforts should also focus on developing multifunctional integrated detection vehicles that can simultaneously inspect both surface and internal structures.Furthermore,progress in fully automated,intelligent systems with precise defect identification and real-time reporting will be essential to significantly improve the efficiency and accuracy of tunnel inspection.展开更多
The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the micro...The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was investigated.Furthermore,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method.The findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and interconnect.This provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron coke.Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke.The metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon atoms.The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure.Moreover,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.展开更多
Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters accordi...Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.展开更多
It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be...It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be solved.A method of 3D structural color turning on periodic metasurfaces fabricated by the microlens array and self-assembly technology was proposed in this study.In the experiment,Polydimethylsiloxane(PDMS)flexible film was used as a substrate,and SiO2 microspheres were scraped into grooves of the PDMS film to form 3D photonic crystal structures.By adjusting the number of blade-coated times and microsphere concentrations,high-saturation structural color micropatterns were obtained.These films were then matched with microlens arrays to produce dynamic graphics with iridescent effects.The results showed that by blade-coated two times and SiO2 microsphere concentrations of 50%are the best conditions.This method demonstrates the potential for being widely applied in the anticounterfeiting printing and ultra-high-resolution display.展开更多
With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electro...With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.展开更多
High-temperature microwave absorbing materials(MAMs)and structures are increasingly appealing due to their critical role in stealth applications under harsh environments.However,the impedance mismatch caused by increa...High-temperature microwave absorbing materials(MAMs)and structures are increasingly appealing due to their critical role in stealth applications under harsh environments.However,the impedance mismatch caused by increased conduction loss often leads to a significant decline in electromagnetic wave absorp-tion(EMWA)performance at elevated temperatures,which severely restricts their practical application.In this study,we propose a novel approach for efficient electromagnetic wave absorption across a wide temperature range using reduced graphene oxide(RGO)/epoxy resin(EP)metacomposites that integrate both electromagnetic parameters and metamaterial design concepts.Due to the discrete distribution of the units,electromagnetic waves can more easily penetrate the interior of materials,thereby exhibiting stable microwave absorption(MA)performance and impedance-matching characteristics suitable across a wide temperature range.Consequently,exceptional MA properties can be achieved within the tem-perature range from 298 to 473 K.Furthermore,by carefully controlling the structural parameters in RGO metacomposites,both the resonant frequency and effective absorption bandwidth(EAB)can be optimized based on precise manipulation of equivalent electromagnetic parameters.This study not only provides an effective approach for the rational design of MA performance but also offers novel insights into achieving super metamaterials with outstanding performance across a wide temperature spectrum.展开更多
Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid compositi...Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).展开更多
Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors....Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors.This dynamic color-changing capability is crucial for applications that require adaptable optical properties,positioning CLCs as key materials in advanced photonic technologies.This review focuses on the mechanisms of dynamic color tuning in CLCs across various forms,including small molecules,cholesteric liquid crystal elastomers(CLCEs),and cholesteric liquid crystal networks(CLCNs),and emphasizes the distinct responsive coloration each structure provides.Key developments in photochromic mechanisms based on azobenzene,dithienylethene,and molecular motor switches,are discussed for their roles in enhancing the stability and tuning range of CLCs.We examine the color-changing behaviors of CLCEs under mechanical stimuli and CLCNs under swelling,highlighting the advantages of each form.Following this,applications of dynamic color-tuning CLCs in information encryption,adaptive camouflage,and smart sensing technologies are explored.The review concludes with an outlook on current challenges and future directions in CLC research,particularly in biomimetic systems and dynamic photonic devices,aiming to broaden their functional applications and impact.展开更多
Reinforced concrete buildings may experience partial damage after earthquakes or some human-induced actions.A decision about the future of those buildings requires detailed analyses,while determining the dynamic chara...Reinforced concrete buildings may experience partial damage after earthquakes or some human-induced actions.A decision about the future of those buildings requires detailed analyses,while determining the dynamic characteristics of a real building in its pre-and post-event situations can guide the analysis.Hence,this study was planned to monitor the dynamic response of an existing six-story,reinforced concrete building with regard to structural damage.The modal characteristics of the original building were initially determined by the use of operational modal analysis.Next,three steps of progressive structural damage were applied to the building.The first damage level peeled off the clear cover of a beam and three columns on a corner of the building’s ground floor.whereas the second and third levels completely razed the damaged columns.Operational modal analysis was repeated at each damage stage to extract the frequencies and detailed mode shapes.Moreover,numerical models based on the finite element method were constructed to confirm the obtained experimental findings.The well-agreed experimental and numerical findings revealed the damage sensitivity of the building’s dynamic response.The quantified amount of frequency change favored a retrofit of the partially damaged buildings rather than their replacement.展开更多
Dynamic structuralcolors can change in response todifferent environmental stimuli.This ability remains effectiveeven when the size of the speciesresponsible for the structural coloris reduced to a few micrometers,prov...Dynamic structuralcolors can change in response todifferent environmental stimuli.This ability remains effectiveeven when the size of the speciesresponsible for the structural coloris reduced to a few micrometers,providing a promising sensingmechanism for solving microenvironmentalsensing problems inmicro-robotics and microfluidics.However, the lack of dynamicstructural colors that can encoderapidly, easily integrate, and accuratelyreflect changes in physical quantities hinders their use in microscale sensing applications. Herein, we present a 2.5-dimensionaldynamic structural color based on nanogratings of heterogeneous materials, which were obtained by interweaving a pH-responsive hydrogelwith an IP-L photoresist. Transverse gratings printed with pH-responsive hydrogels elongated the period of longitudinal grating in the swollenstate, resulting in pH-tuned structural colors at a 45° incidence. Moreover, the patterned encoding and array printing of dynamic structuralcolors were achieved using grayscale stripe images to accurately encode the periods and heights of the nanogrid structures. Overall, dynamicstructural color networks exhibit promising potential for applications in information encryption and in situ sensing for microfluidic chips.展开更多
Columnar jointed rock mass(CJRM)combines and mosaic of slender rock columns with different height-to-width(H/W)ratios.Revealing the correlation of the mechanical behavior of individual rock columns with internal facto...Columnar jointed rock mass(CJRM)combines and mosaic of slender rock columns with different height-to-width(H/W)ratios.Revealing the correlation of the mechanical behavior of individual rock columns with internal factors(H/W ratio and material strength)and external factor(lateral pressure)is fundamental to understanding the deterioration of CJRM.We adopt a numerical scheme that combines a statistical meso-damage constitutive model with a finite element formulation based on finite deformation,which can simultaneously consider both material failure and structural instability of the rock columns.Compression tests of rock columns with different H/W ratios and material strengths under varying lateral pressures were conducted to analyze the macro-strength features and failure modes.The numerical results show that increasing the material strength can improve the macro-strength,while the effect of H/W ratio is the opposite.Both increases can promote the conversion of failure modes,and the evolution process is as follows:material failure-induced structural instability→synergy and competition between material failure and structural instability→structural instability-induced material failure.Notably,for the last failure mode,an increase in lateral pressure decreases the macro-strength of the rock column and heightens its instability risk.This finding provides new insights into the response of rocks with different H/W ratios under lateral pressure,extending beyond traditional material-based perspectives.According to the position of the failure mode demarcation line,the failure mode of the rock column can be regulated.展开更多
Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium me...Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium metal batteries(MMBs).Nevertheless,the large charge-radius ratio of Mg^(2+)induces the strong interactions of Mg^(2+)with solvent molecules of electrolyte and anionic framework of cathode,resulting in a notable voltage polarization and structural deterioration during cycling process.Herein,an in-situ multi-scale structural engineering is proposed to activate the interlayer-expanded V_(2)O_(5)cathode(pillared by tetrabutylammonium cation)via adding hexadecyltrimethylammonium bromide(CTAB)additive into electrolyte.During cycling,the in-situ incorporation of CTA^(+)not only enhances the electrostatic shielding effect and Mg species migration,but also stabilizes the interlayer spacing.Besides,CTA^(+)is prone to be adsorbed on cathode surface and induces the loss-free pulverization and amorphization of electroactive grains,leading to the pronounced effect of intercalation pseudocapacitance.CTAB additive also enables to scissor the Mg^(2+)solvation sheath and tailor the insertion mode of Mg species,further endowing V_(2)O_(5)cathode with fast reaction kinetics.Based on these merits,the corresponding V2O5‖Mg full cells exhibit the remarkable rate performance with capacities as high as 317.6,274.4,201.1,and 132.7 mAh g^(-1)at the high current densities of 0.1,0.2,0.5,and 1 A g^(-1),respectively.Moreover,after 1000 cycles,the capacity is still preserved to be 90,4 mAh g^(-1)at 1 A g^(-1)with an average coulombic efficiency of~100%.Our strategy of synergetic modulations of cathode host and electrolyte solvation structures provides new guidance for the development of high-rate,large-capacity,and long-life MMBs.展开更多
Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor strugg...Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.展开更多
This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and stru...This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and structural response of the platform are studied,considering the actual platform motion and free surface rise under extreme sea states.First,the effects of the wave frequency and direction on the wave-induced loads and dynamic responses were examined.The motion at a wave direction angle of 0°is relatively low.On this basis,the angle constrained by the two sides of the Sharp Eagle floaters should be aligned with the main wave direction to avoid significant platform motion under extreme sea states.Additionally,the structural response of the platform,including the wave-absorbing floaters,is investigated.The results highlighted that the conditions or locations where yielding,buckling,and fatigue failures occur were different.In this context,the connection area of the Sharp Eagle floaters and platform is prone to yielding failure under oblique wave action,whereas the pontoon and side of the Sharp Eagle floaters are prone to buckling failure during significant vertical motion.Additionally,fatigue damage is most likely to occur at the connection between the middle column on both sides of the Sharp Eagle floaters and the pontoons.The findings of this paper revealed an intrinsic connection between wave-induced loads and the dynamic and structural responses of the platform,which provides a useful reference for the improved design of WECs.展开更多
Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for ...Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for the mild synthesis conditions and high conversion efficiency to obtain 2,5-furan dicarboxylic acid(FDCA),but there still remain problems such as limited yield,short cycle life,and ambiguous reaction mechanism.Despite many reviews highlighting a variety of electrocatalysts for electrochemical oxidation of HMF,a detailed discussion of the structural modulation of catalyst and the underlying catalytic mechanism is still lacking.We herein provide a comprehensive summary of the recent development of electrochemical oxidation of HMF to FDCA,particularly focusing on the mechanism studies as well as the advanced strategies developed to regulate the structure and optimize the performance of the electrocatalysts,including heterointerface construction,defect engineering,single-atom engineering,and in situ reconstruction.Experimental characterization techniques and theoretical calculation methods for mechanism and active site studies are elaborated,and challenges and future directions of electrochemical oxidation of HMF are also prospected.This review will provide guidance for designing advanced catalysts and deepening the understanding of the reaction mechanism beneath electrochemical oxidation of HMF to FDCA.展开更多
This study aimed to investigate the effect of ultrasound-assisted alkaline extraction(UAE)(at 20 kHz and different powers of 0,200,300,400,500 and 600 W for 10 min)on the yield,structure and emulsifying properties of ...This study aimed to investigate the effect of ultrasound-assisted alkaline extraction(UAE)(at 20 kHz and different powers of 0,200,300,400,500 and 600 W for 10 min)on the yield,structure and emulsifying properties of chickpea protein isolate(CPI).Compared with the non-ultrasound group,ultrasound treatment at 400 W resulted in the largest increase in CPI yield,and both the particle size and turbidity decreased with increasing ultrasound power from 0 to 400 W.The scanning electron microscope results showed a uniform structural distribution of CPI.Moreover,itsα-helix content increased,β-sheet content decreased,and total sulfhydryl group content and endogenous fluorescence intensity rose,illustrating that UAE changed the secondary and tertiary structure of CPI.At 400 W,the solubility of the emulsion increased to 63.18%,and the best emulsifying properties were obtained;the emulsifying activity index(EAI)and emulsifying stability index(ESI)increased by 85.42%and 46.78%,respectively.Furthermore,the emulsion droplets formed were smaller and more uniform.In conclusion,proper UAE power conditions increased the extraction yield and protein content of CPI,and effectively improved its structure and emulsifying characteristics.展开更多
In this paper,the failure caused by HRAM loads which were generated by high-speed projectile penetration,and protection technology of the fluid-filled structure were explored.A bubble was preset on the projectile traj...In this paper,the failure caused by HRAM loads which were generated by high-speed projectile penetration,and protection technology of the fluid-filled structure were explored.A bubble was preset on the projectile trajectory in a fluid-filled structure.Based on the reflection and transmission phenomena of pressure waves at the gas-liquid interface and the compressibility characteristics of gases,a numerical analysis was conducted on the influence of preset bubble on projectile penetration and structural failure characteristics.The results indicate that the secondary water-entry impact phenomenon occurs when a preset bubble exists on the projectile trajectory,leading to the secondary water entry impact loads.The rarefaction waves reflected on the surface of the preset bubble cause the attenuation ratio of the initial impact pressure peak to reach 68.8%and the total specific impulse attenuation ratio to reach 48.6%.Furthermore,the larger the bubble,the faster the projectile,and the more obvious the attenuation effect.Moreover,due to the compressibility of the bubble,the global deformation attenuation ratio of the front and rear walls can reach over 80%.However,the larger the bubble size,the faster the projectile velocity,the smaller the local deformation attenuation effect of the rear wall,and the more severe the failure at the perforation of the rear wall.展开更多
The operational state of distillation columns significantly impacts product quality and production efficiency.However,due to the complex operation and diverse influencing factors,ensuring the safety and efficient oper...The operational state of distillation columns significantly impacts product quality and production efficiency.However,due to the complex operation and diverse influencing factors,ensuring the safety and efficient operation of the distillation columns becomes paramount.This research combines passive acoustic monitoring with artificial intelligence techniques,proposed a technology based on residual network(ResNet),which involves the transformation of the acoustic signals emitted by three distillation columns under different operating states.The acoustic signals were initially in one-dimensional waveform format and then converted into two-dimensional Mel-Frequency Cepstral Coefficients spectrogram database using fast Fourier transform.Ultimately,this database was employed to train a ResNet for the purpose of identifying the operational states of the distillation columns.Through this approach,the operational states of distillation columns were monitored.Various faults,including flooding,entrainment,dry-tray,etc.,were diagnosed with an accuracy of 98.91%.Moreover,an intermediate transitional state between normal operation and fault was identified and accurately recognized by the proposed method.Under the transitional state,the acoustic signals achieved an accuracy of 97.85%on the ResNet,which enables early warnings before faults occur,enhancing the safety of chemical production processes.The approach presents a powerful tool for the monitoring and diagnosis of chemical equipment,particularly distillation columns,ensuring the safety and efficiency.展开更多
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states...A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.展开更多
基金The National Natural Science Foundation of China(No.52222804,U21A20154).
文摘Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.
文摘Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,and defects behind the structure.To address the need for rapid detection of different defect types,the current state of rapid detection technologies and equipment,both domestically and internationally,is systematically reviewed.The research reveals that surface defect detection technologies and equipment have developed rapidly in recent years.Notably,the integration of machine vision and laser scanning technologies have significantly improved detection efficiency and accuracy,achieving crack detection precision of up to 0.1 mm.However,the non-contact rapid detection of internal and behind-the-structure defects remains constrained by hardware limitations,with traditional detection remaining dominant.Nevertheless,phased array radar,ultrasonic,and acoustic vibration detection technologies have become research hotspots in recent years,offering promising directions for detecting these challenging defect types.Additionally,the application of multisensor fusion technology in rapid detection equipment has further enhanced detection capabilities.Devices such as cameras,3D laser scanners,infrared thermal imagers,and radar demonstrate significant advantages in rapid detection.Future research in tunnel inspection should prioritize breakthroughs in rapid detection technologies for internal and behind-the-structure defects.Efforts should also focus on developing multifunctional integrated detection vehicles that can simultaneously inspect both surface and internal structures.Furthermore,progress in fully automated,intelligent systems with precise defect identification and real-time reporting will be essential to significantly improve the efficiency and accuracy of tunnel inspection.
基金financially supported by the National Science Foundation of China(Nos.51974212 and 52274316)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202116)+1 种基金the Science and Technology Major Project of Wuhan(No.2023020302020572)the Foundation of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(No.FMRUlab23-04)。
文摘The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was investigated.Furthermore,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method.The findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and interconnect.This provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron coke.Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke.The metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon atoms.The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure.Moreover,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
基金supported by the Innovation Foundation of Provincial Education Department of Gansu(2024B-005)the Gansu Province National Science Foundation(22YF7GA182)the Fundamental Research Funds for the Central Universities(No.lzujbky2022-kb01)。
文摘Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.
文摘It is of great scientific significance to construct a 3D dynamic structural color with a special color effect based on the microlens array.However,the problems of imperfect mechanisms and poor color quality need to be solved.A method of 3D structural color turning on periodic metasurfaces fabricated by the microlens array and self-assembly technology was proposed in this study.In the experiment,Polydimethylsiloxane(PDMS)flexible film was used as a substrate,and SiO2 microspheres were scraped into grooves of the PDMS film to form 3D photonic crystal structures.By adjusting the number of blade-coated times and microsphere concentrations,high-saturation structural color micropatterns were obtained.These films were then matched with microlens arrays to produce dynamic graphics with iridescent effects.The results showed that by blade-coated two times and SiO2 microsphere concentrations of 50%are the best conditions.This method demonstrates the potential for being widely applied in the anticounterfeiting printing and ultra-high-resolution display.
基金supported by the Surface Project of Local De-velopment in Science and Technology Guided by Central Govern-ment(No.2021ZYD0041)the National Natural Science Founda-tion of China(Nos.52377026 and 52301192)+3 种基金the Natural Science Foundation of Shandong Province(No.ZR2019YQ24)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Special Financial of Shandong Province(Struc-tural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Tal-ent Teams)the“Sanqin Scholars”Innovation Teams Project of Shaanxi Province(Clean Energy Materials and High-Performance Devices Innovation Team of Shaanxi Dongling Smelting Co.,Ltd.).
文摘With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.
基金supported by the National Nature Science Foundation of China(Nos.22305066 and 52372041).
文摘High-temperature microwave absorbing materials(MAMs)and structures are increasingly appealing due to their critical role in stealth applications under harsh environments.However,the impedance mismatch caused by increased conduction loss often leads to a significant decline in electromagnetic wave absorp-tion(EMWA)performance at elevated temperatures,which severely restricts their practical application.In this study,we propose a novel approach for efficient electromagnetic wave absorption across a wide temperature range using reduced graphene oxide(RGO)/epoxy resin(EP)metacomposites that integrate both electromagnetic parameters and metamaterial design concepts.Due to the discrete distribution of the units,electromagnetic waves can more easily penetrate the interior of materials,thereby exhibiting stable microwave absorption(MA)performance and impedance-matching characteristics suitable across a wide temperature range.Consequently,exceptional MA properties can be achieved within the tem-perature range from 298 to 473 K.Furthermore,by carefully controlling the structural parameters in RGO metacomposites,both the resonant frequency and effective absorption bandwidth(EAB)can be optimized based on precise manipulation of equivalent electromagnetic parameters.This study not only provides an effective approach for the rational design of MA performance but also offers novel insights into achieving super metamaterials with outstanding performance across a wide temperature spectrum.
基金supported by PTDC-01778/2022-NeuroDev3D,iNOVA4Health(UIDB/04462/2020 and UIDP/04462/2020)LS4FUTURE(LA/P/0087/2020)。
文摘Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).
基金financially supported by the National Natural Science Foundation of China(Nos.52233001,51927805,and 52173110)the Innovation Program of Shanghai Municipal Education Commission(No.2023ZKZD07)the Shanghai Rising-Star Program(No.22QA1401200)。
文摘Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors.This dynamic color-changing capability is crucial for applications that require adaptable optical properties,positioning CLCs as key materials in advanced photonic technologies.This review focuses on the mechanisms of dynamic color tuning in CLCs across various forms,including small molecules,cholesteric liquid crystal elastomers(CLCEs),and cholesteric liquid crystal networks(CLCNs),and emphasizes the distinct responsive coloration each structure provides.Key developments in photochromic mechanisms based on azobenzene,dithienylethene,and molecular motor switches,are discussed for their roles in enhancing the stability and tuning range of CLCs.We examine the color-changing behaviors of CLCEs under mechanical stimuli and CLCNs under swelling,highlighting the advantages of each form.Following this,applications of dynamic color-tuning CLCs in information encryption,adaptive camouflage,and smart sensing technologies are explored.The review concludes with an outlook on current challenges and future directions in CLC research,particularly in biomimetic systems and dynamic photonic devices,aiming to broaden their functional applications and impact.
基金supported by the Scientific and Technological Research Council of Türkiye(TUBITAK)under Research Grant 116M254.
文摘Reinforced concrete buildings may experience partial damage after earthquakes or some human-induced actions.A decision about the future of those buildings requires detailed analyses,while determining the dynamic characteristics of a real building in its pre-and post-event situations can guide the analysis.Hence,this study was planned to monitor the dynamic response of an existing six-story,reinforced concrete building with regard to structural damage.The modal characteristics of the original building were initially determined by the use of operational modal analysis.Next,three steps of progressive structural damage were applied to the building.The first damage level peeled off the clear cover of a beam and three columns on a corner of the building’s ground floor.whereas the second and third levels completely razed the damaged columns.Operational modal analysis was repeated at each damage stage to extract the frequencies and detailed mode shapes.Moreover,numerical models based on the finite element method were constructed to confirm the obtained experimental findings.The well-agreed experimental and numerical findings revealed the damage sensitivity of the building’s dynamic response.The quantified amount of frequency change favored a retrofit of the partially damaged buildings rather than their replacement.
基金supported by the National Natural Science Foundation of China(Grant No.61925307).
文摘Dynamic structuralcolors can change in response todifferent environmental stimuli.This ability remains effectiveeven when the size of the speciesresponsible for the structural coloris reduced to a few micrometers,providing a promising sensingmechanism for solving microenvironmentalsensing problems inmicro-robotics and microfluidics.However, the lack of dynamicstructural colors that can encoderapidly, easily integrate, and accuratelyreflect changes in physical quantities hinders their use in microscale sensing applications. Herein, we present a 2.5-dimensionaldynamic structural color based on nanogratings of heterogeneous materials, which were obtained by interweaving a pH-responsive hydrogelwith an IP-L photoresist. Transverse gratings printed with pH-responsive hydrogels elongated the period of longitudinal grating in the swollenstate, resulting in pH-tuned structural colors at a 45° incidence. Moreover, the patterned encoding and array printing of dynamic structuralcolors were achieved using grayscale stripe images to accurately encode the periods and heights of the nanogrid structures. Overall, dynamicstructural color networks exhibit promising potential for applications in information encryption and in situ sensing for microfluidic chips.
基金supported in part by the National Natural Science Foundation of China(4227233052079019)+1 种基金the Liaoning Province Science and Technology Plan Joint Program(Applied Basic Research Project)(2023JH2/101700340)the Fundamental Research Funds for the Central Universities(DUT24ZD135).
文摘Columnar jointed rock mass(CJRM)combines and mosaic of slender rock columns with different height-to-width(H/W)ratios.Revealing the correlation of the mechanical behavior of individual rock columns with internal factors(H/W ratio and material strength)and external factor(lateral pressure)is fundamental to understanding the deterioration of CJRM.We adopt a numerical scheme that combines a statistical meso-damage constitutive model with a finite element formulation based on finite deformation,which can simultaneously consider both material failure and structural instability of the rock columns.Compression tests of rock columns with different H/W ratios and material strengths under varying lateral pressures were conducted to analyze the macro-strength features and failure modes.The numerical results show that increasing the material strength can improve the macro-strength,while the effect of H/W ratio is the opposite.Both increases can promote the conversion of failure modes,and the evolution process is as follows:material failure-induced structural instability→synergy and competition between material failure and structural instability→structural instability-induced material failure.Notably,for the last failure mode,an increase in lateral pressure decreases the macro-strength of the rock column and heightens its instability risk.This finding provides new insights into the response of rocks with different H/W ratios under lateral pressure,extending beyond traditional material-based perspectives.According to the position of the failure mode demarcation line,the failure mode of the rock column can be regulated.
基金supported by the National Natural Science Foundation of China(52372249)support by the Program of Shanghai Academic Research Leader(21XD1424400)。
文摘Vanadium pentoxide(V_(2)O_(5))displays the characteristics of high theoretical specific capacity,high operating voltage,and adjustable layered structure,possessing the considerable potential as cathode in magnesium metal batteries(MMBs).Nevertheless,the large charge-radius ratio of Mg^(2+)induces the strong interactions of Mg^(2+)with solvent molecules of electrolyte and anionic framework of cathode,resulting in a notable voltage polarization and structural deterioration during cycling process.Herein,an in-situ multi-scale structural engineering is proposed to activate the interlayer-expanded V_(2)O_(5)cathode(pillared by tetrabutylammonium cation)via adding hexadecyltrimethylammonium bromide(CTAB)additive into electrolyte.During cycling,the in-situ incorporation of CTA^(+)not only enhances the electrostatic shielding effect and Mg species migration,but also stabilizes the interlayer spacing.Besides,CTA^(+)is prone to be adsorbed on cathode surface and induces the loss-free pulverization and amorphization of electroactive grains,leading to the pronounced effect of intercalation pseudocapacitance.CTAB additive also enables to scissor the Mg^(2+)solvation sheath and tailor the insertion mode of Mg species,further endowing V_(2)O_(5)cathode with fast reaction kinetics.Based on these merits,the corresponding V2O5‖Mg full cells exhibit the remarkable rate performance with capacities as high as 317.6,274.4,201.1,and 132.7 mAh g^(-1)at the high current densities of 0.1,0.2,0.5,and 1 A g^(-1),respectively.Moreover,after 1000 cycles,the capacity is still preserved to be 90,4 mAh g^(-1)at 1 A g^(-1)with an average coulombic efficiency of~100%.Our strategy of synergetic modulations of cathode host and electrolyte solvation structures provides new guidance for the development of high-rate,large-capacity,and long-life MMBs.
基金financially supported by the National Key Research and Development Program of China(No.2022YFA1205300 and No.2022YFA1205304)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2022ZD103).
文摘Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3003805)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022356)Guangzhou Basic and Applied Basic Research Project(Grant No.2023A04J0955).
文摘This paper presents a new type of triangular Sharp Eagle wave energy converter(WEC)platform.On the basis of the linear potential flow theory and the finite element analysis method,the hydrodynamic performance and structural response of the platform are studied,considering the actual platform motion and free surface rise under extreme sea states.First,the effects of the wave frequency and direction on the wave-induced loads and dynamic responses were examined.The motion at a wave direction angle of 0°is relatively low.On this basis,the angle constrained by the two sides of the Sharp Eagle floaters should be aligned with the main wave direction to avoid significant platform motion under extreme sea states.Additionally,the structural response of the platform,including the wave-absorbing floaters,is investigated.The results highlighted that the conditions or locations where yielding,buckling,and fatigue failures occur were different.In this context,the connection area of the Sharp Eagle floaters and platform is prone to yielding failure under oblique wave action,whereas the pontoon and side of the Sharp Eagle floaters are prone to buckling failure during significant vertical motion.Additionally,fatigue damage is most likely to occur at the connection between the middle column on both sides of the Sharp Eagle floaters and the pontoons.The findings of this paper revealed an intrinsic connection between wave-induced loads and the dynamic and structural responses of the platform,which provides a useful reference for the improved design of WECs.
基金National Natural Science Foundation of China(22272150,22302177)Major Program of Zhejiang Provincial Natural Science Foundation of China(LD22B030002)+2 种基金Zhejiang Provincial Ten Thousand Talent Program(2021R51009)Public Technology Application Project of Jinhua City(2022-4-067)Self Designed Scientific Research of Zhejiang Normal University(2021ZS0604)。
文摘Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for the mild synthesis conditions and high conversion efficiency to obtain 2,5-furan dicarboxylic acid(FDCA),but there still remain problems such as limited yield,short cycle life,and ambiguous reaction mechanism.Despite many reviews highlighting a variety of electrocatalysts for electrochemical oxidation of HMF,a detailed discussion of the structural modulation of catalyst and the underlying catalytic mechanism is still lacking.We herein provide a comprehensive summary of the recent development of electrochemical oxidation of HMF to FDCA,particularly focusing on the mechanism studies as well as the advanced strategies developed to regulate the structure and optimize the performance of the electrocatalysts,including heterointerface construction,defect engineering,single-atom engineering,and in situ reconstruction.Experimental characterization techniques and theoretical calculation methods for mechanism and active site studies are elaborated,and challenges and future directions of electrochemical oxidation of HMF are also prospected.This review will provide guidance for designing advanced catalysts and deepening the understanding of the reaction mechanism beneath electrochemical oxidation of HMF to FDCA.
文摘This study aimed to investigate the effect of ultrasound-assisted alkaline extraction(UAE)(at 20 kHz and different powers of 0,200,300,400,500 and 600 W for 10 min)on the yield,structure and emulsifying properties of chickpea protein isolate(CPI).Compared with the non-ultrasound group,ultrasound treatment at 400 W resulted in the largest increase in CPI yield,and both the particle size and turbidity decreased with increasing ultrasound power from 0 to 400 W.The scanning electron microscope results showed a uniform structural distribution of CPI.Moreover,itsα-helix content increased,β-sheet content decreased,and total sulfhydryl group content and endogenous fluorescence intensity rose,illustrating that UAE changed the secondary and tertiary structure of CPI.At 400 W,the solubility of the emulsion increased to 63.18%,and the best emulsifying properties were obtained;the emulsifying activity index(EAI)and emulsifying stability index(ESI)increased by 85.42%and 46.78%,respectively.Furthermore,the emulsion droplets formed were smaller and more uniform.In conclusion,proper UAE power conditions increased the extraction yield and protein content of CPI,and effectively improved its structure and emulsifying characteristics.
文摘In this paper,the failure caused by HRAM loads which were generated by high-speed projectile penetration,and protection technology of the fluid-filled structure were explored.A bubble was preset on the projectile trajectory in a fluid-filled structure.Based on the reflection and transmission phenomena of pressure waves at the gas-liquid interface and the compressibility characteristics of gases,a numerical analysis was conducted on the influence of preset bubble on projectile penetration and structural failure characteristics.The results indicate that the secondary water-entry impact phenomenon occurs when a preset bubble exists on the projectile trajectory,leading to the secondary water entry impact loads.The rarefaction waves reflected on the surface of the preset bubble cause the attenuation ratio of the initial impact pressure peak to reach 68.8%and the total specific impulse attenuation ratio to reach 48.6%.Furthermore,the larger the bubble,the faster the projectile,and the more obvious the attenuation effect.Moreover,due to the compressibility of the bubble,the global deformation attenuation ratio of the front and rear walls can reach over 80%.However,the larger the bubble size,the faster the projectile velocity,the smaller the local deformation attenuation effect of the rear wall,and the more severe the failure at the perforation of the rear wall.
基金the National Natural Science Foundation of China(22308079)the Natural Science Foundation of Hebei Province,China(B2022202008,B2023202025)the Science and Technology Project of Hebei Education Department,China(BJK2022037).
文摘The operational state of distillation columns significantly impacts product quality and production efficiency.However,due to the complex operation and diverse influencing factors,ensuring the safety and efficient operation of the distillation columns becomes paramount.This research combines passive acoustic monitoring with artificial intelligence techniques,proposed a technology based on residual network(ResNet),which involves the transformation of the acoustic signals emitted by three distillation columns under different operating states.The acoustic signals were initially in one-dimensional waveform format and then converted into two-dimensional Mel-Frequency Cepstral Coefficients spectrogram database using fast Fourier transform.Ultimately,this database was employed to train a ResNet for the purpose of identifying the operational states of the distillation columns.Through this approach,the operational states of distillation columns were monitored.Various faults,including flooding,entrainment,dry-tray,etc.,were diagnosed with an accuracy of 98.91%.Moreover,an intermediate transitional state between normal operation and fault was identified and accurately recognized by the proposed method.Under the transitional state,the acoustic signals achieved an accuracy of 97.85%on the ResNet,which enables early warnings before faults occur,enhancing the safety of chemical production processes.The approach presents a powerful tool for the monitoring and diagnosis of chemical equipment,particularly distillation columns,ensuring the safety and efficiency.
基金supports from the National Natural Science Foundation of China (Grant Nos.52004143 and 52374095)the open fund for the Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines (Grant No.SKLMRDPC21KF06).
文摘A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.
