Vibrated fluidized bed air classification is completely different from traditional screening in principle. It extracts fine coal from moist raw coal by entrainment of an ascending airflow in a vibrated fluidized bed. ...Vibrated fluidized bed air classification is completely different from traditional screening in principle. It extracts fine coal from moist raw coal by entrainment of an ascending airflow in a vibrated fluidized bed. Pilot tests showed that air classification efficiencies varied from 74.85% to 93.84% at cut-size 6, 4, 3, 2, 1, and 0.5 mm when free moisture of coal is in the range of 1.7% to 9.5%, and ash contents of fine coal products were 2%～3% lower than those of the same size fractions in feed, and 4%～10% lower than those of feeds for most cases because of the density differences between coal and waste, which is beneficial to producing lower ash fine coal from raw coal as fuel of blast furnaces or pulverized coal firing boilers. A commercial unit of 100 t/h has been in smooth operation, and several 300～400 t/h units are in plan or construction.展开更多
We investigate the rotational dynamics of a low-density sphere on the free surface of a vertically vibrated granular material（VGM）. The dynamical behavior of the sphere is influenced by the external energy input fro...We investigate the rotational dynamics of a low-density sphere on the free surface of a vertically vibrated granular material（VGM）. The dynamical behavior of the sphere is influenced by the external energy input from an electromagnetic shaker which is proportional to ε,where ε is equal to the ratio between the square of the dimensionless acceleration Γ and the square of the vibration frequency f of the container. Empirical results reveal that as the VGM transits from local-to-global convection,an increase in ε generally corresponds to an increase in the magnitudes of the rotational ω（RS） and translational v（CM） velocities of the sphere, an increase in the observed tilting angle θ（bed） of the VGM bed, and a decrease in the time t（wall） it takes the sphere to roll down the tilted VGM bed and hit the container wall. During unstable convection, an increase in ε results in a sharp decrease in the sphere＇s peak and mean ω（RS）,and a slight increase in t（wall）.For the range of ε values covered in this study, the sphere may execute persistent rotation, wobbling or jamming, depending on the vibration parameters and the resulting convective flow in the system.展开更多
Heat transfer coefficients between an immersed horizontal tube and an aerated vibrated fluidized bed are measured. There is a maximum value in the h-P experimental curve. The heat transfer coefficient increases with d...Heat transfer coefficients between an immersed horizontal tube and an aerated vibrated fluidized bed are measured. There is a maximum value in the h-P experimental curve. The heat transfer coefficient increases with decreases in particle diameter in the fully fluidized region. The particle density has less effect on the heat transfer coefficients. High amplitude and low frequency, or low amplitude and high frequency are favorable to heat transfer. Exceedingly high gas velocity is unfavorable to the surface-bed heat transfer. A model based on the 'pocket' theory was proposed for predicting the surface-to-bed heat transfer coefficients in fully fluidized region. The predictions from the model were compared with observed data. The reasonable fit suggests the adequacy of the model.展开更多
Previous experimental investigations have shown that when a narrow pipe is inserted into a granular bed and is vibrated vertically but the granular bed is kept still, the grains in the bed can enter the pipe and rise ...Previous experimental investigations have shown that when a narrow pipe is inserted into a granular bed and is vibrated vertically but the granular bed is kept still, the grains in the bed can enter the pipe and rise against gravity along the pipe and finally stabilized at a certain height. The growth velocity and final stable height of the grain column inside the pipe can be controlled by varying the vibration conditions. In this paper, we discuss those experimental findings. We establish a mathematic relation between the grain column height（h） and time（t）, and by using the relation we discuss the change of the growth velocity（ dh/ dt） and acceleration（ d^2h/ dt^2） with t and h, respectively. We also analyze the mechanism of the rising motion of the grains during vibration. Furthermore, we derive a theoretical expression for describing the final stable height（h st）, which shows that the main factors influencing the height are vibration strength（Γ）, bulk density of grains,inner diameter of the pipe, and vibration frequency, and that h st increases nonlinearly in the presence of air and linearly in a vacuum environment with increasing Γ.展开更多
We present a short retrospective review of the existing literature about the dynamics of(dry)granular matter under the effect of vibrations.The main objective is the development of an integrated resource where vital i...We present a short retrospective review of the existing literature about the dynamics of(dry)granular matter under the effect of vibrations.The main objective is the development of an integrated resource where vital information about past findings and recent discoveries is provided in a single treatment.Special attention is paid to those works where successful synthetic routes to as-yet unknown phenomena were identified.Such landmark results are analyzed,while smoothly blending them with a history of the field and introducing possible categorizations of the prevalent dynamics.Although no classification is perfect,and it is hard to distillate general properties out of specific observations or realizations,two possible ways to interpret the existing results are defined according to the type of forcing or the emerging(ensuing)regime of motion.In particular,first results concerning the case where vibrations and gravity are concurrent(vertical shaking)are examined,then the companion situation with vibrations perpendicular to gravity(horizontal shaking)is described.Universality classes are introduced as follows:(1)Regimes where sand self-organizes leading to highly regular geometrical“pulsating”patterns(thin layer case);(2)Regimes where the material undergoes“fluidization”and develops an internal multicellular convective state(tick layers case);(3)Regimes where the free interface separating the sand from the overlying gas changes inclination or develops a kind a patterned configuration consisting of stable valleys and mountains or travelling waves;(4)Regimes where segregation is produced,i.e.,particles of a given size tend to be separated from the other grains(deep containers).Where possible,an analogy or parallelism is drawn with respect to the companion field of fluid-dynamics for which the assumption of“continuum”can be applied.展开更多
Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties durin...Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.展开更多
Noise interference critically impairs the stability and data accuracy of sensing systems.However,current suppression strategies fail to concurrently mitigate intrinsic system noise and extrinsic environmental noise.Th...Noise interference critically impairs the stability and data accuracy of sensing systems.However,current suppression strategies fail to concurrently mitigate intrinsic system noise and extrinsic environmental noise.This study introduces a composite denoising approach to address this challenge.This method is based on the ameliorated ellipse fitting algorithm(AEFA)and adaptive successive variational mode decomposition(ASVMD).This algorithm employs AEFA to eliminate system noise tightly coupled with direct-current and alternating-current components in the interference signal,thereby obtaining a phase signal containing only environmental noise.The ASVMD technique adaptively extracts environmental noise components predominantly present in the phase signal.To achieve optimal decomposition results automatically,the permutation entropy criterion is employed to refine decomposition parameters.The correlation coefficient is utilized to differentiate effective components from noise components in the decomposition results.Experimental results indicate that the combined AEFA and ASVMD algorithm effectively suppresses both system and environmental noises.When applied to 50 Hz vibration signal processing,the proposed approach achieves a noise reduction of 17.81 dB and a phase resolution of 35.14μrad/√Hz.Given the excellent performance of the noise suppression,the proposed approach holds great application potential in high-performance interferometric sensing systems.展开更多
The granulation process in a vibratedfluidized bed with immersed horizontal heating tubes was studied in this paper,with small monoammonium phosphate particles as the initial particles and monoammonium phosphate soluti...The granulation process in a vibratedfluidized bed with immersed horizontal heating tubes was studied in this paper,with small monoammonium phosphate particles as the initial particles and monoammonium phosphate solution sprayed on them.The concrete influences on the granulating performance of the immersed horizontal heating power,fluidizing gas velocity,vibration frequency and amplitude had been analyzed theoretically.The results show that appropriate vibration intensity is a preferred condition for the growth of partials,but thefine dust will become much more along with prolonged vibration.Increasing the heating power is beneficial to raise the growth rate.Particles will grow faster if thefluidizing gas velocity is higher,but this will cause morefine dust.The optimized condition of A=0.002 m,f=6.67 Hz,u=1.4 m/s was given after the analysis of the experimental results.In the end,a semiempirical formula was derived from the experiment data,and the calculation results show good agreement with the experimental data.展开更多
The vibrational fluidized bed is innovatively adopted to regenerate the particulate filter medium for the purification of crude syn-thesis gas from the coal gasification process.Characteristic research of vibrated flu...The vibrational fluidized bed is innovatively adopted to regenerate the particulate filter medium for the purification of crude syn-thesis gas from the coal gasification process.Characteristic research of vibrated fluidized beds during dust-containing particulate filter medium regeneration has been carried out.The ideal transport model of particulate filter medium on the distributor is estab-lished and verified by using experiments.The mean residence time of the particulate filter medium can be reduced by 72%from 5.5 to 1.5 min with an increase in the working frequency from 50 to 60 Hz.The thickness of the bed layer is linearly increased with the feeding rate of the particulate filter medium under ideal working conditions.The resistance models of the fluidizing air are built up and validated,and they can be used to calculate the pressure drop of the static bed layer of the particulate filter medium on the flu-idizing air distributor,which is the maximum value of the dynamic bed layer with the same thickness.The fluidizing air makes the mean residence time of the particulate filter medium decrease by 50%and reduces the difference in the particulate mean residence time under different feeding-rate conditions.The regeneration effect of dust-containing filter medium particles in a vibrated fluidized bed is evaluated.Fluidizing air with superficial velocity ranging from 0 to 0.6~0.9 m·s-1 makes the regeneration efficiency increase from 29.41%to 70.59~88.24%.This article provides a reference for the industrial application of a vibrated fluidized bed for the par-ticulate filter medium recycling system.展开更多
Under the condition of frequent replacement of wind tunnel models,multiple types of wind tunnel models are fixed by a slender support sting with low stiffness damping.When excited by wind load,various models produce r...Under the condition of frequent replacement of wind tunnel models,multiple types of wind tunnel models are fixed by a slender support sting with low stiffness damping.When excited by wind load,various models produce random multi-dimensional vibration with different characteristics,which makes it impossible to obtain accurate and efficient aerodynamic data.Therefore,in order to ensure the reliable and efficient conduction of wind tunnel test,a wind-tunnel-modeladaptive vibration control method is proposed in this paper.First,the split type adaptive vibration suppression structure is designed.Second,the multi-dimensional vibration characteristic characterization method is derived and the vibration characteristic identification method of the system is designed.Then,a vibration state estimation model is established according to the identification results of vibration characteristics,and a multi-actuator cooperative control method based on vibration state estimation is constructed.Finally,a model-adaptive vibration control system is built,and vibration characteristics identification and hammer experiments are carried out for two types of typical models.The results show that the proposed model-adaptive vibration control method increases the equivalent damping ratio of pitch and yaw dimensions of the high-aspect-ratio class model by 8.19 times and 48.81 times,respectively.The equivalent damping ratio of pitch and yaw dimensions of the highslenderness-ratio class model is increased by 16.44 and 5.43 times,respectively.It provides a strong guarantee for the reliable and efficient development of multi-type wind tunnel test tasks.展开更多
High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-p...High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-principles calculations,we elucidate crucial corrections to the vibrational and superconducting properties arising from quantum and anharmonic ionic vibrations of SnH4 in P63/mmc phase at 150–240 GPa.Compared with the classical harmonic approximation,inclusion of these effects results in a pronounced softening(over 500 cm^(−1))of hydrogen-derived optical phonon modes,and increases the superconducting critical temperature(Tc)from 65 K to 79 K(μ^(*)=0.1;isotropic Migdal–Eliashberg theory),corresponding to a 22%enhancement.For μ^(*)=0.13,the predicted Tc is approximately 70 K.Analysis of the Eliashberg spectral function confirms that hydrogen vibrational modes constitute the dominant tuning mechanism.These results provide quantitative insights into quantum ionic effects in hydride superconductors.展开更多
Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolatio...Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.展开更多
Dear Editors,This letter,reflecting on my research career,is dedi-cated to Professor Qingshi Zhu for his 80th Birthday.Part of this letter is based on my comment“A 20-year journey on the invention of vibrational phot...Dear Editors,This letter,reflecting on my research career,is dedi-cated to Professor Qingshi Zhu for his 80th Birthday.Part of this letter is based on my comment“A 20-year journey on the invention of vibrational photothermal microscopy”published in the May 2025 Nature Meth-ods Focus Issue on Bond-Selective Imaging[1].展开更多
A novel vibration isolation system designed for superior performance in low-frequency environments is proposed in this work.The isolator is based on a unique hexagonal arrangement of linear springs,allowing for an adj...A novel vibration isolation system designed for superior performance in low-frequency environments is proposed in this work.The isolator is based on a unique hexagonal arrangement of linear springs,allowing for an adjustable geometric configuration via the initial inclination angle.Based on the principle of Lagrangian mechanics,the equation of motion governing the structural dynamics is rigorously derived.The system is modeled as a strongly nonlinear single-degree-of-freedom dynamical system,loaded with a normalized payload and subject to harmonic base excitation.To analyze the steady-state response,the harmonic balance method is employed,providing accurate predictions of the payload's vibration amplitude and displacement transmissibility as functions of both the base excitation amplitude and frequency.The analysis reveals a direct relationship between the isolator's geometric and stiffness parameters and its load-bearing capacity,leading to the identification of three distinct operational regimes.Depending on the unloaded initial inclination angle,the equivalent stiffness ratio,and the payload design configuration,the system can exhibit one of three vibration isolation modes:(i)the quasizero stiffness(QZS)isolation mode,(ii)the zero linear stiffness with controllable nonlinear stiffness,and(iii)the full-band perfect zero stiffness.The vibration isolation performance of the proposed structure is thoroughly discussed for all three oscillation modes in terms of frequency response curves,displacement transmissibility,and time-domain responses.The key novel finding is that this structure can operate as a full-band,high-performance vibration isolator when the initial inclination angle is designed to be a right angle,enabling full isolation of the maximum possible payload.Moreover,the analytical results and numerical simulations demonstrate that the isolator's displacement transmissibility T with the unit dB tends to-∞as the air-damping coefficient approaches zero,enabling ideal vibration isolation across the entire excitation frequency range.These analytical insights are validated through comprehensive numerical simulations,which show excellent agreement with the theoretical predictions.展开更多
A design idea for single-component metamaterial plates is proposed to achieve the thermal stability of flexural wave bandgap by the perforated and pre-curved patterns.The band structure analysis suggests that perforat...A design idea for single-component metamaterial plates is proposed to achieve the thermal stability of flexural wave bandgap by the perforated and pre-curved patterns.The band structure analysis suggests that perforation can release part of the in-plane thermal expansion to weaken the softening effect of thermal stress.Introducing precurved components to the perforated structure will stop the decrement of the bandgap frequency in thermal environment,and even make the frequency higher with appropriate structural parameters.The bending stiffness of the heated plate is enhanced by the thermal deflection induced stiffening effect of the pre-curved components.The segmented pre-curved component presents a strong ability to resist the thermal influence on the flexural wave bandgap.A simplified model is established for the local structure of the precurved component.The theoretical calculations explain the thermally induced frequency increment of the bandgap and the discrepancy in the thermal response between the two pre-curved models.The transmittance of flexural wave validates the effectiveness of the proposed design.展开更多
With the convergence of sensor technology,artificial intelligence,and the Internet of Things,intelligent vibration monitoring systems are undergoing transformative development.This evolution imposes stringent demands ...With the convergence of sensor technology,artificial intelligence,and the Internet of Things,intelligent vibration monitoring systems are undergoing transformative development.This evolution imposes stringent demands on the miniaturization,low power consumption,high integration,and environmental adaptability of transducers.Graphene,renowned for its superlative physicochemical attributes,holds significant promise for application in micro-and nanoelectromechanical systems(M/NEMS).However,the inherent central symmetry of graphene restricts its utility in piezoelectric devices.Inspired by the sensilla trichoidea of spiders,a threedimensional(3D)cilia-like monolayer graphene omnidirectional vibration transducer(CGVT)based on a stress-induced self-assembly mechanism is fabricated,demonstrating notable performance and high-temperature resistance.Furthermore,3D vibration vector decoding is realized via an omnidirectional decoupling algorithm based on one-dimensional convolutional neural networks(1DCNN)to achieve precise discrimination of vibration directions.The 3D bionic vibration-sensing system incorporates a spider web structure into a bionic cilia MEMS chip through a gold wire bonding process,enabling the realization of three distinct mechanisms for vibration detection and recognition.In particular,these devices are manufactured using silicon-based semiconductor processing techniques and MEMS fabrication methodologies,leading to a substantial reduction in the dimensions of individual components compared to traditional counterparts.展开更多
While the instantaneous power of triboelectric nanogenerators(TENGs)has significantly increased,the average power remains unsatisfactory.Achieving a continuous and stable output remains a significant challenge.Herein,...While the instantaneous power of triboelectric nanogenerators(TENGs)has significantly increased,the average power remains unsatisfactory.Achieving a continuous and stable output remains a significant challenge.Herein,a self-excited vibration TENG inspired by woodpeckers is proposed.This structure converts gravitational potential energy into the continuous vibration of a cantilever beam.A dynamic simulation model of the system is established,and the influence of different structural parameters on the motion characteristics and electrical performance is discussed.Meanwhile,the experimental results indicate that the accelerated motion(approximate free-fall motion)is transformed into approximately uniform velocity motion.For a 3 cm^(2) TENG,the instantaneous power density reaches 2.03 W m^(-2),and the average power is 127%higher than that of the conventional cantilever beam mode.The proposed self-excited vibration mechanism is a promising approach for enhancing the average power and operational duration of TENGs.It shows great potential in fluid energy harvesting.展开更多
This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality...This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.展开更多
The presented study analyses the impact of hysteresis on the response of mechanical systems.The main objective is to determine how the hysteretic models influence the system behaviour and if they can be utilised to de...The presented study analyses the impact of hysteresis on the response of mechanical systems.The main objective is to determine how the hysteretic models influence the system behaviour and if they can be utilised to describe a damaged or a faulty system.The hysteretic models are able to describe various types of nonlinear behaviour that can reflect the wear or damage of the system components.The data obtained from these models can possibly serve as a basis for the advanced approaches,such as digital twin modelling and predictive maintenance.All the results presented in this study were obtained in the MATLAB environment.The first part of the study provides a concise review of hysteretic models and compares them under the condition of equal energy dissipation per loading cycle.The models considered include the linear,bilinear,Bouc-Wen,Wang-Wen,and generalised Bouc-Wen models.The second part focuses on the development of a mechanical model and the implementation of the mentioned hysteretic models.The stochastic modelling of the driving forces is carried out using the Kanai-Tajimi differential model.The results show that the hysteretic models noticeably influence the treated model.This is also reflected in the frequency domain.The behaviour of hysteretic systems suggests increased energy dissipation combined with the changes in stiffness of the suspension components.Among the presented models,the asymmetric models can be considered as the most suitable for further modelling of damaged systems.展开更多
This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A...This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.展开更多
文摘Vibrated fluidized bed air classification is completely different from traditional screening in principle. It extracts fine coal from moist raw coal by entrainment of an ascending airflow in a vibrated fluidized bed. Pilot tests showed that air classification efficiencies varied from 74.85% to 93.84% at cut-size 6, 4, 3, 2, 1, and 0.5 mm when free moisture of coal is in the range of 1.7% to 9.5%, and ash contents of fine coal products were 2%～3% lower than those of the same size fractions in feed, and 4%～10% lower than those of feeds for most cases because of the density differences between coal and waste, which is beneficial to producing lower ash fine coal from raw coal as fuel of blast furnaces or pulverized coal firing boilers. A commercial unit of 100 t/h has been in smooth operation, and several 300～400 t/h units are in plan or construction.
基金Supported by the CHED-FDP II Program of the Commission on Higher Education of the Philippines
文摘We investigate the rotational dynamics of a low-density sphere on the free surface of a vertically vibrated granular material（VGM）. The dynamical behavior of the sphere is influenced by the external energy input from an electromagnetic shaker which is proportional to ε,where ε is equal to the ratio between the square of the dimensionless acceleration Γ and the square of the vibration frequency f of the container. Empirical results reveal that as the VGM transits from local-to-global convection,an increase in ε generally corresponds to an increase in the magnitudes of the rotational ω（RS） and translational v（CM） velocities of the sphere, an increase in the observed tilting angle θ（bed） of the VGM bed, and a decrease in the time t（wall） it takes the sphere to roll down the tilted VGM bed and hit the container wall. During unstable convection, an increase in ε results in a sharp decrease in the sphere＇s peak and mean ω（RS）,and a slight increase in t（wall）.For the range of ε values covered in this study, the sphere may execute persistent rotation, wobbling or jamming, depending on the vibration parameters and the resulting convective flow in the system.
基金Supported by the National Natural Science Foundation of China(No.29576253).
文摘Heat transfer coefficients between an immersed horizontal tube and an aerated vibrated fluidized bed are measured. There is a maximum value in the h-P experimental curve. The heat transfer coefficient increases with decreases in particle diameter in the fully fluidized region. The particle density has less effect on the heat transfer coefficients. High amplitude and low frequency, or low amplitude and high frequency are favorable to heat transfer. Exceedingly high gas velocity is unfavorable to the surface-bed heat transfer. A model based on the 'pocket' theory was proposed for predicting the surface-to-bed heat transfer coefficients in fully fluidized region. The predictions from the model were compared with observed data. The reasonable fit suggests the adequacy of the model.
文摘Previous experimental investigations have shown that when a narrow pipe is inserted into a granular bed and is vibrated vertically but the granular bed is kept still, the grains in the bed can enter the pipe and rise against gravity along the pipe and finally stabilized at a certain height. The growth velocity and final stable height of the grain column inside the pipe can be controlled by varying the vibration conditions. In this paper, we discuss those experimental findings. We establish a mathematic relation between the grain column height（h） and time（t）, and by using the relation we discuss the change of the growth velocity（ dh/ dt） and acceleration（ d^2h/ dt^2） with t and h, respectively. We also analyze the mechanism of the rising motion of the grains during vibration. Furthermore, we derive a theoretical expression for describing the final stable height（h st）, which shows that the main factors influencing the height are vibration strength（Γ）, bulk density of grains,inner diameter of the pipe, and vibration frequency, and that h st increases nonlinearly in the presence of air and linearly in a vacuum environment with increasing Γ.
文摘We present a short retrospective review of the existing literature about the dynamics of(dry)granular matter under the effect of vibrations.The main objective is the development of an integrated resource where vital information about past findings and recent discoveries is provided in a single treatment.Special attention is paid to those works where successful synthetic routes to as-yet unknown phenomena were identified.Such landmark results are analyzed,while smoothly blending them with a history of the field and introducing possible categorizations of the prevalent dynamics.Although no classification is perfect,and it is hard to distillate general properties out of specific observations or realizations,two possible ways to interpret the existing results are defined according to the type of forcing or the emerging(ensuing)regime of motion.In particular,first results concerning the case where vibrations and gravity are concurrent(vertical shaking)are examined,then the companion situation with vibrations perpendicular to gravity(horizontal shaking)is described.Universality classes are introduced as follows:(1)Regimes where sand self-organizes leading to highly regular geometrical“pulsating”patterns(thin layer case);(2)Regimes where the material undergoes“fluidization”and develops an internal multicellular convective state(tick layers case);(3)Regimes where the free interface separating the sand from the overlying gas changes inclination or develops a kind a patterned configuration consisting of stable valleys and mountains or travelling waves;(4)Regimes where segregation is produced,i.e.,particles of a given size tend to be separated from the other grains(deep containers).Where possible,an analogy or parallelism is drawn with respect to the companion field of fluid-dynamics for which the assumption of“continuum”can be applied.
基金financially supported by National Key Research and Development Programs (Nos.2022YFD1700403 and 2023YFD1700303)National Natural Science Foundation of China (Nos.12274128 and 12250003)+2 种基金Shanghai Rising-Star Program (No.21QA1402600)the support of NYU-ECNU Center for Computational Chemistry at NYU Shanghaithe University of Bath and the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University (No.2020ZD01) for support。
文摘Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.
文摘Noise interference critically impairs the stability and data accuracy of sensing systems.However,current suppression strategies fail to concurrently mitigate intrinsic system noise and extrinsic environmental noise.This study introduces a composite denoising approach to address this challenge.This method is based on the ameliorated ellipse fitting algorithm(AEFA)and adaptive successive variational mode decomposition(ASVMD).This algorithm employs AEFA to eliminate system noise tightly coupled with direct-current and alternating-current components in the interference signal,thereby obtaining a phase signal containing only environmental noise.The ASVMD technique adaptively extracts environmental noise components predominantly present in the phase signal.To achieve optimal decomposition results automatically,the permutation entropy criterion is employed to refine decomposition parameters.The correlation coefficient is utilized to differentiate effective components from noise components in the decomposition results.Experimental results indicate that the combined AEFA and ASVMD algorithm effectively suppresses both system and environmental noises.When applied to 50 Hz vibration signal processing,the proposed approach achieves a noise reduction of 17.81 dB and a phase resolution of 35.14μrad/√Hz.Given the excellent performance of the noise suppression,the proposed approach holds great application potential in high-performance interferometric sensing systems.
文摘The granulation process in a vibratedfluidized bed with immersed horizontal heating tubes was studied in this paper,with small monoammonium phosphate particles as the initial particles and monoammonium phosphate solution sprayed on them.The concrete influences on the granulating performance of the immersed horizontal heating power,fluidizing gas velocity,vibration frequency and amplitude had been analyzed theoretically.The results show that appropriate vibration intensity is a preferred condition for the growth of partials,but thefine dust will become much more along with prolonged vibration.Increasing the heating power is beneficial to raise the growth rate.Particles will grow faster if thefluidizing gas velocity is higher,but this will cause morefine dust.The optimized condition of A=0.002 m,f=6.67 Hz,u=1.4 m/s was given after the analysis of the experimental results.In the end,a semiempirical formula was derived from the experiment data,and the calculation results show good agreement with the experimental data.
基金This study was supported by No.9300190001 project in National Institute of Clean-and-Low-Carbon Energy.
文摘The vibrational fluidized bed is innovatively adopted to regenerate the particulate filter medium for the purification of crude syn-thesis gas from the coal gasification process.Characteristic research of vibrated fluidized beds during dust-containing particulate filter medium regeneration has been carried out.The ideal transport model of particulate filter medium on the distributor is estab-lished and verified by using experiments.The mean residence time of the particulate filter medium can be reduced by 72%from 5.5 to 1.5 min with an increase in the working frequency from 50 to 60 Hz.The thickness of the bed layer is linearly increased with the feeding rate of the particulate filter medium under ideal working conditions.The resistance models of the fluidizing air are built up and validated,and they can be used to calculate the pressure drop of the static bed layer of the particulate filter medium on the flu-idizing air distributor,which is the maximum value of the dynamic bed layer with the same thickness.The fluidizing air makes the mean residence time of the particulate filter medium decrease by 50%and reduces the difference in the particulate mean residence time under different feeding-rate conditions.The regeneration effect of dust-containing filter medium particles in a vibrated fluidized bed is evaluated.Fluidizing air with superficial velocity ranging from 0 to 0.6~0.9 m·s-1 makes the regeneration efficiency increase from 29.41%to 70.59~88.24%.This article provides a reference for the industrial application of a vibrated fluidized bed for the par-ticulate filter medium recycling system.
基金supported in part by the National Natural Science Foundation of China(Nos.52475550,52305095)in part by the Key R&D Project of Liaoning Province,China(No.2023JH2/101800026)。
文摘Under the condition of frequent replacement of wind tunnel models,multiple types of wind tunnel models are fixed by a slender support sting with low stiffness damping.When excited by wind load,various models produce random multi-dimensional vibration with different characteristics,which makes it impossible to obtain accurate and efficient aerodynamic data.Therefore,in order to ensure the reliable and efficient conduction of wind tunnel test,a wind-tunnel-modeladaptive vibration control method is proposed in this paper.First,the split type adaptive vibration suppression structure is designed.Second,the multi-dimensional vibration characteristic characterization method is derived and the vibration characteristic identification method of the system is designed.Then,a vibration state estimation model is established according to the identification results of vibration characteristics,and a multi-actuator cooperative control method based on vibration state estimation is constructed.Finally,a model-adaptive vibration control system is built,and vibration characteristics identification and hammer experiments are carried out for two types of typical models.The results show that the proposed model-adaptive vibration control method increases the equivalent damping ratio of pitch and yaw dimensions of the high-aspect-ratio class model by 8.19 times and 48.81 times,respectively.The equivalent damping ratio of pitch and yaw dimensions of the highslenderness-ratio class model is increased by 16.44 and 5.43 times,respectively.It provides a strong guarantee for the reliable and efficient development of multi-type wind tunnel test tasks.
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No.24JP126)the National Natural Science Foundation of China (Grant No.62174136)the Natural Science Basic Research Program of Shaanxi Province (Grant No.2025JC-YBMS-063)。
文摘High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-principles calculations,we elucidate crucial corrections to the vibrational and superconducting properties arising from quantum and anharmonic ionic vibrations of SnH4 in P63/mmc phase at 150–240 GPa.Compared with the classical harmonic approximation,inclusion of these effects results in a pronounced softening(over 500 cm^(−1))of hydrogen-derived optical phonon modes,and increases the superconducting critical temperature(Tc)from 65 K to 79 K(μ^(*)=0.1;isotropic Migdal–Eliashberg theory),corresponding to a 22%enhancement.For μ^(*)=0.13,the predicted Tc is approximately 70 K.Analysis of the Eliashberg spectral function confirms that hydrogen vibrational modes constitute the dominant tuning mechanism.These results provide quantitative insights into quantum ionic effects in hydride superconductors.
基金supported by the Natural Science Foundation of China(Grant No.52275091)Natural Science Foundation of Liaoning Province(Grant No.2022-MS-125)+1 种基金Shenyang Natural Science Foundation(Grant No.23-503-6-02)Fundamental Research Funds for the Central Universities(Grant No.N2303011).
文摘Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.
文摘Dear Editors,This letter,reflecting on my research career,is dedi-cated to Professor Qingshi Zhu for his 80th Birthday.Part of this letter is based on my comment“A 20-year journey on the invention of vibrational photothermal microscopy”published in the May 2025 Nature Meth-ods Focus Issue on Bond-Selective Imaging[1].
基金Project supported by the National Key R&D Program of China(No.2023YFE0125900)。
文摘A novel vibration isolation system designed for superior performance in low-frequency environments is proposed in this work.The isolator is based on a unique hexagonal arrangement of linear springs,allowing for an adjustable geometric configuration via the initial inclination angle.Based on the principle of Lagrangian mechanics,the equation of motion governing the structural dynamics is rigorously derived.The system is modeled as a strongly nonlinear single-degree-of-freedom dynamical system,loaded with a normalized payload and subject to harmonic base excitation.To analyze the steady-state response,the harmonic balance method is employed,providing accurate predictions of the payload's vibration amplitude and displacement transmissibility as functions of both the base excitation amplitude and frequency.The analysis reveals a direct relationship between the isolator's geometric and stiffness parameters and its load-bearing capacity,leading to the identification of three distinct operational regimes.Depending on the unloaded initial inclination angle,the equivalent stiffness ratio,and the payload design configuration,the system can exhibit one of three vibration isolation modes:(i)the quasizero stiffness(QZS)isolation mode,(ii)the zero linear stiffness with controllable nonlinear stiffness,and(iii)the full-band perfect zero stiffness.The vibration isolation performance of the proposed structure is thoroughly discussed for all three oscillation modes in terms of frequency response curves,displacement transmissibility,and time-domain responses.The key novel finding is that this structure can operate as a full-band,high-performance vibration isolator when the initial inclination angle is designed to be a right angle,enabling full isolation of the maximum possible payload.Moreover,the analytical results and numerical simulations demonstrate that the isolator's displacement transmissibility T with the unit dB tends to-∞as the air-damping coefficient approaches zero,enabling ideal vibration isolation across the entire excitation frequency range.These analytical insights are validated through comprehensive numerical simulations,which show excellent agreement with the theoretical predictions.
基金Project supported by the National Natural Science Foundation of China(Nos.12102321 and 52192633)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2025JCYBMS-050)。
文摘A design idea for single-component metamaterial plates is proposed to achieve the thermal stability of flexural wave bandgap by the perforated and pre-curved patterns.The band structure analysis suggests that perforation can release part of the in-plane thermal expansion to weaken the softening effect of thermal stress.Introducing precurved components to the perforated structure will stop the decrement of the bandgap frequency in thermal environment,and even make the frequency higher with appropriate structural parameters.The bending stiffness of the heated plate is enhanced by the thermal deflection induced stiffening effect of the pre-curved components.The segmented pre-curved component presents a strong ability to resist the thermal influence on the flexural wave bandgap.A simplified model is established for the local structure of the precurved component.The theoretical calculations explain the thermally induced frequency increment of the bandgap and the discrepancy in the thermal response between the two pre-curved models.The transmittance of flexural wave validates the effectiveness of the proposed design.
基金supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(No.2024ZD1003100)the National Key R&D Program of China(Grant No.2024YFC2813700)。
文摘With the convergence of sensor technology,artificial intelligence,and the Internet of Things,intelligent vibration monitoring systems are undergoing transformative development.This evolution imposes stringent demands on the miniaturization,low power consumption,high integration,and environmental adaptability of transducers.Graphene,renowned for its superlative physicochemical attributes,holds significant promise for application in micro-and nanoelectromechanical systems(M/NEMS).However,the inherent central symmetry of graphene restricts its utility in piezoelectric devices.Inspired by the sensilla trichoidea of spiders,a threedimensional(3D)cilia-like monolayer graphene omnidirectional vibration transducer(CGVT)based on a stress-induced self-assembly mechanism is fabricated,demonstrating notable performance and high-temperature resistance.Furthermore,3D vibration vector decoding is realized via an omnidirectional decoupling algorithm based on one-dimensional convolutional neural networks(1DCNN)to achieve precise discrimination of vibration directions.The 3D bionic vibration-sensing system incorporates a spider web structure into a bionic cilia MEMS chip through a gold wire bonding process,enabling the realization of three distinct mechanisms for vibration detection and recognition.In particular,these devices are manufactured using silicon-based semiconductor processing techniques and MEMS fabrication methodologies,leading to a substantial reduction in the dimensions of individual components compared to traditional counterparts.
基金support from the National Science Fund for Distinguished Young Scholars of China(Grant No.62225308)the National Natural Science Foundation of China(Grant No.62473246).
文摘While the instantaneous power of triboelectric nanogenerators(TENGs)has significantly increased,the average power remains unsatisfactory.Achieving a continuous and stable output remains a significant challenge.Herein,a self-excited vibration TENG inspired by woodpeckers is proposed.This structure converts gravitational potential energy into the continuous vibration of a cantilever beam.A dynamic simulation model of the system is established,and the influence of different structural parameters on the motion characteristics and electrical performance is discussed.Meanwhile,the experimental results indicate that the accelerated motion(approximate free-fall motion)is transformed into approximately uniform velocity motion.For a 3 cm^(2) TENG,the instantaneous power density reaches 2.03 W m^(-2),and the average power is 127%higher than that of the conventional cantilever beam mode.The proposed self-excited vibration mechanism is a promising approach for enhancing the average power and operational duration of TENGs.It shows great potential in fluid energy harvesting.
基金National Natural Science Foundation of China under Grant Nos.51979205 and 51939008。
文摘This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.
基金supported by projects KEGA,Nos.002ŽU-4/2023,and 005ŽU-4/2024,and by the project VEGA,No.1/0423/23.
文摘The presented study analyses the impact of hysteresis on the response of mechanical systems.The main objective is to determine how the hysteretic models influence the system behaviour and if they can be utilised to describe a damaged or a faulty system.The hysteretic models are able to describe various types of nonlinear behaviour that can reflect the wear or damage of the system components.The data obtained from these models can possibly serve as a basis for the advanced approaches,such as digital twin modelling and predictive maintenance.All the results presented in this study were obtained in the MATLAB environment.The first part of the study provides a concise review of hysteretic models and compares them under the condition of equal energy dissipation per loading cycle.The models considered include the linear,bilinear,Bouc-Wen,Wang-Wen,and generalised Bouc-Wen models.The second part focuses on the development of a mechanical model and the implementation of the mentioned hysteretic models.The stochastic modelling of the driving forces is carried out using the Kanai-Tajimi differential model.The results show that the hysteretic models noticeably influence the treated model.This is also reflected in the frequency domain.The behaviour of hysteretic systems suggests increased energy dissipation combined with the changes in stiffness of the suspension components.Among the presented models,the asymmetric models can be considered as the most suitable for further modelling of damaged systems.
文摘This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.
