Submarine seep plumes are a natural phenomenon in which different types of gases migrate through deep or shallow subsurface sediments and leak into seawater in pressure gradient.When detected using acoustic data,the l...Submarine seep plumes are a natural phenomenon in which different types of gases migrate through deep or shallow subsurface sediments and leak into seawater in pressure gradient.When detected using acoustic data,the leaked gases frequently exhibit a flame-like structure.We numerically modelled the relationship between the seismic response characteristic and bubble volume fraction to establish the bubble volume fraction in the submarine seep plume.Results show that our models are able to invert and predict the bubble volume fraction from field seismic oceanography data,by which synthetic seismic sections in different dominant frequencies could be numerically simulated,seismic attribute sections(e.g.,instantaneous amplitude,instantaneous frequency,and instantaneous phase)extracted,and the correlation between the seismic attributes and bubble volume fraction be quantitatively determined with functional equations.The instantaneous amplitude is positively correlated with bubble volume fraction,while the instantaneous frequency and bubble volume fraction are negatively correlated.In addition,information entropy is introduced as a proxy to quantify the relationship between the instantaneous phase and bubble volume fraction.As the bubble volume fraction increases,the information entropy of the instantaneous phase increases rapidly at the beginning,followed by a slight upward trend,and finally stabilizes.Therefore,under optimal noise conditions,the bubble volume fraction of submarine seep plumes can be inverted and predicted based on seismic response characteristics in terms of seismic attributes.展开更多
This paper presents a new three-dimensional(3D) volume measurement approach of bubble in gas-liquid two-phase flow. According to the dual perspective imaging principle,bubble feature images can be captured from two di...This paper presents a new three-dimensional(3D) volume measurement approach of bubble in gas-liquid two-phase flow. According to the dual perspective imaging principle,bubble feature images can be captured from two different view angles. The least square ellipse fitting algorithm is used to figure out the feature parameters from the captured images. Then the 3D volume of bubble can be quantitatively measured. Compaerd with the traditional volume estimation methods based on single perspective imaging,it can effectively reduce the loss of bubble feature information. In the experiment,the 3D volume reconstruction of bubbles from dual perspective images is conducted,and the variation of bubble volume in the bubble rising process is studied. The results show that the measurement accuracy based on the proposed 3D method is higher than those based on traditional methods. The volume of rising bubble is periodically changed,which indicates that bubble achieves periodic rotation and deformation in the rising process.展开更多
The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-...The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-consuming nature,and high costs,laboratory methods are often not preferred.Machine learning,with its efficiencyand rapid convergence,has emerged as a promising alternative for PVT properties estimation.This study employs the modified particle swarm optimization-based group method of data handling(PSO-GMDH)to develop predictive models for estimating both the oil formation volume factor(OFVF)and bubble point pressure(P_(b)).Data from the Mpyo oil fieldin Uganda were used to create the models.The input parameters included solution gas-oil ratio(R_(s)),oil American Petroleum Institute gravity(API),specificgravity(SG),and reservoir temperature(T).The results demonstrated that PSO-GMDH outperformed backpropagation neural networks(BPNN)and radial basis function neural networks(RBFNN),achieving higher correlation coefficientsand lower prediction errors during training and testing.For OFVF prediction,PSO-GMDH yielded a correlation coefficient(R)of 0.9979(training)and 0.9876(testing),with corresponding root mean square error(RMSE)values of 0.0021 and 0.0099,and mean absolute error(MAE)values of 0.00055 and 0.00256,respectively.For P_(b)prediction,R was 0.9994(training)and 0.9876(testing),with RMSE values of 6.08 and 8.26,and MAE values of 1.35 and 2.63.The study also revealed that R_(s)significantlyimpacts OFVF and P_(b)predictions compared to other input parameters.The models followed physical laws and remained stable,demonstrating that PSO-GMDH is a robust and efficientmethod for predicting OFVF and P_(b),offering a time and cost-effective alternative.展开更多
In this study,the dynamic characteristics of microscale floating bubbles near the vertical wall are studied.This occurrence is common in industrial and natural phenomena.Although many studies have been conducted on mi...In this study,the dynamic characteristics of microscale floating bubbles near the vertical wall are studied.This occurrence is common in industrial and natural phenomena.Although many studies have been conducted on microscale bubbles,few studies investigate floating bubbles with very small Reynolds number(Re)near the wall,which is the main research goal of this study.Therefore,this study establishes a model for the ascent of small-scale bubbles near a vertical wall using the interFoam solver in OpenFOAM.This study investigates the influences of diverse viscosity parameters,varying distances from the wall,and different gas flow rates on the terminal velocity,deformation,and motion trajectory of bubbles.The results reveal that as liquid viscosity increases,the Re of bubbles gradually decreases and reaches a minimum of 0.012,which is similar to the Re of micrometer-sized bubbles in water.The characteristics of the wall-induced force in the longitudinal direction are closely related to the changes in liquid viscosity.Under low-viscosity conditions,the induced lift is the principal form of action,whereas under high-viscosity conditions,it is primarily manifested as induced drag.展开更多
This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow con...This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.展开更多
Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath...Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath dynamics.A physical model and a 3D gas-slag-steel transient bottom-blowing numerical model of a 150 t EAF were established to investigate the bubble behaviour and flow characteristics throughout the molten steel bath and slag layer under bottom-blowing,with referring to gas flow rate,plug diameter,plug arrangement and injection angle.Results indicate that the average bubble sizes experience increase,dynamic stability and decrease in molten steel bath and then undergo decrease and increase after entering into slag layer for all bottom-blowing modes.The bubble numbers exhibit the opposing trends during the process.Increase in gas flow rate leads to a significant rise in average bubble size but a decrease in number,average dwelling time and the spread area of bubbles in slag layer.Increase in plug diameter causes an opposite impact.The effect of plug arrangement radii on bubbles is almost negligible.Increasing the injection angle results in an increase in bubble size and a decrease in both bubble number and dwelling time in slag layer.The slag foaming potential was discussed referring to the bubble size,number and dwelling time in slag layer.Increase in gas flow rate and plug diameters can significantly enhance the fluids flow through increasing average flow velocity,decreasing mixing time and dead zone ratio of molten bath.Plug arrangement radius and injection angle express nonlinear correlation with average flow velocity and dead zone ratio,and the plug arrangement radius of 0.5R(R represents the radius of bottom circle of EAF model)and injection angle of 15°perform better in enhancing dynamics of molten bath.A group of bottom-blowing parameters are proposed to achieve better comprehensive performance of bubble-induced slag foaming and molten bath dynamics.展开更多
350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by...350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by annealing at 750℃ for 10,100,and 300 h,respectively.The results showed that material swelling due to helium bubble coarsening was almost not observed in either the LPBF or rolled samples after 10 h of annealing duration.Rapid coarsening and swelling of bubbles occurred in the rolled samples,but only moderate bubble growth occurred in the LPBF sample after annealing for 100 h.After annealing for 300 h,the helium bubbles in both samples tended to grow steadily.For 10 h of annealing,the irradiated samples were in a disequilibrium state,and the apparent activation energy(E^(act))calculated by the Arrhenius model determined that helium atoms tended to diffuse through the displacement mechanism,and helium bubbles grew under the migration and coalescence(MC)mechanism.With annealing times over 100 h,the high-density dislocations and nano-oxide particles in the LPBF sample still had a strong trapping effect on the movement and growth of helium bubbles.After annealing for 300 h,the cellular subgrains in the LPBF sample decomposed,and the nano-oxide particles had no trapping effect on the helium bubbles.At this time,the dislocation structure played a primary role in suppressing the growth of helium bubbles,and the radiation resistance of the LPBF sample remained superior to that of the rolled samples.展开更多
The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab b...The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.展开更多
Legged robots have considerable potential for traversing unstructured situations;nonetheless,their inflexible frameworks often constrain adaptability and obstacle negotiation.The study article presents a revolutionary...Legged robots have considerable potential for traversing unstructured situations;nonetheless,their inflexible frameworks often constrain adaptability and obstacle negotiation.The study article presents a revolutionary Soft Tri-Legged Robot(STLR)that improves movement and obstacle-avoidance skills by using a bio-inspired pneumatic artificial muscle(Bubble Artificial Muscles)and a bio-inspired tactile sensor(TacTip).The STLR is activated by BAMs,which are flexible,pneu-matic-driven actuators that provide fine control over forward,backward,and steering movements.Obstacle identification and avoidance are facilitated by the TacTip sensor,which delivers tactile input for traversing unstructured terrains.We delineate the mechanical features of the BAMs,assess the functionality of the robot's legs,and elaborate on the incorpora-tion of the tactile sensing system.Experimental results demonstrate that the STLR can effectively achieve multi-directional flexible movement and obstacle avoidance through a cross-modal perception-actuation mechanism.This study highlights the promise of soft robotics for search and rescue,medical aid,and autonomous exploration,while delineating difficulties and opportunities for future improvements in functionality and efficiency.展开更多
The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,an...The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.展开更多
This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble col...This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble column reactor was simulated. The grid independence study was first conducted and a grid size of 1.0 mm was adopted in order to minimize the computing time without compromising the accuracy of the results. The predictions were validated by comparing the experimental studies reported in the literature. It was found that all surface tension models can describe the bubble rise and bubble plume in a column with slight deviations.展开更多
A coupled method describing gas–solid two-phase flow has been proposed to numerically study the bubble formation at a single orifice in gas-fluidized beds.Solid particles are traced with smoothed particle hydrodynami...A coupled method describing gas–solid two-phase flow has been proposed to numerically study the bubble formation at a single orifice in gas-fluidized beds.Solid particles are traced with smoothed particle hydrodynamics,whereas gas phase is discretized by finite volume method.Drag force,gas pressure gradient,and volume fraction are used to couple the two methods.The effect of injection velocities,particle sizes,and particle densities on bubble growth is analyzed using the coupled method.The simulation results,obtained for two-dimensional geometries,include the shape and diameter size of a bubble as a function of time;such results are compared with experimental data,previous numerical results,and other approximate model predictions reported in the literature.Moreover,the flow profiles of gas and particle phases and the temperature distribution by the heat transfer model around the forming bubble are also discussed.All results show that the coupled method efficiently describes of the bubble formation in fluidized beds.The proposed method is applicable for solving gas–solid two-phase flow in fluidization.展开更多
In order to address the bubble formation and movement in air-water two-phase flow,single bubble rising in stagnant water is experimentally studied by digital image processing.Bubbles are released individually from the...In order to address the bubble formation and movement in air-water two-phase flow,single bubble rising in stagnant water is experimentally studied by digital image processing.Bubbles are released individually from the submerged orifices with different diameters(1.81 mm,2.07 mm,2.98 mm,3.92 mm)at different detachment frequency.Images are recorded by a high-speed video camera and processed by digital image processing technique. The factors impacting the formed volume of bubble are discussed.The experimental results showed that a threshold of gas flow rate(400 mm 3 ·s- 1)divides the bubble formation into two regimes:the constant volume regime and the growing volume regime.Especially for the growing volume regime,the surface tension is taken into account.The bubble volume is consisted of two parts:the surface tension impacting part and the gas volume flow rate impacting part.An improved correlation for bubble volume prediction is developed for the two regimes and better coincidence with the experiment data than the previous models is obtained.展开更多
The multi-orifice plate gas sparger, mainly composed of a multi-orifice plate and a gas chamber, is one of the most common sparger facilities.The aeration performance of multi-orifice plate has a close relation with t...The multi-orifice plate gas sparger, mainly composed of a multi-orifice plate and a gas chamber, is one of the most common sparger facilities.The aeration performance of multi-orifice plate has a close relation with the multiorifice plate configuration.In addition, the weeping phenomenon has a considerable influence on the gas chamber condition which affects the bubble detachment volume directly.This paper conducts a set of visual experiments to study the influence of multi-orifice configuration and gas chamber condition on the aeration performance of gas sparger.For multi-orifice plate, an improved theoretical model is proposed which considers the wave effect of the previous bubbles generated from adjacent orifices and the variance of the number of active bubbling orifice.A parameter is proposed to evaluate the aeration performance in order to overcome the difficulty caused by the randomness of bubble formation process.The experimental results suggest that the gas chamber filled with water is in favor of large bubble formation.The influence of the pitch of orifice on aeration performance can only be observed in high-restricted case.According to the theoretical model and experimental results, the influences of gas flow rate and the number of open orifices on the aeration performance are analyzed and a design criterion for the number of open orifice is proposed.展开更多
Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer a...Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure drop.Additional simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,respectively.The simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be reached.The primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic pressure.When the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,respectively.The bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.展开更多
Mechanisms for the evolution of a single spherical bubble subjected to sound excitation in water are studied from the viewpoint of nonlinear dynamics.First,the shooting method is combined with a Poincaré map to o...Mechanisms for the evolution of a single spherical bubble subjected to sound excitation in water are studied from the viewpoint of nonlinear dynamics.First,the shooting method is combined with a Poincaré map to obtain the fixed point for the case of forced oscillation in volume.Then,the stabilities are judged by Floquet theory and the bifurcation theorem.Moreover,the transitions of bubble oscillation in volume due to sound excitation in water are explained from the viewpoint of nonlinear dynamics in detail.The results show that with an increase in sound frequency,the period-1 oscillation becomes unstable,and oscillation behaves in a double-periodic manner,then a quasi-periodic manner,and finally chaotically.Additionally,with an increase of the amplitude of the sound pressure,the bubble eventually oscillates with chaos via a series of period-doubling bifurcations.展开更多
This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signa...This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signals and degrade positioning accuracy.Managed by the Indonesian Geospatial Information Agency(BIG),the Indonesia Continuously Operating Reference Station(Ina-CORS)network comprises over 300 GNSS receivers spanning equatorial to southern low-latitude regions.Ina-CORS is uniquely situated to monitor EPB generation,zonal drift,and dissipation across Southeast Asia.We provide a practical tool for EPB research,by sharing two-dimensional rate of Total Electron Content(TEC)change index(ROTI)derived from this network.We generate ROTI maps with a 10-minute resolution,and samples from May 2024 are publicly available for further scientific research.Two preliminary findings from the ROTI maps of Ina-CORS are noteworthy.First,the Ina-CORS ROTI maps reveal that the irregularities within a broader EPB structure persist longer,increasing the potential for these irregularities to migrate farther eastward.Second,we demonstrate that combined ROTI maps from Ina-CORS and GNSS receivers in East Asia and Australia can be used to monitor the development of ionospheric irregularities in Southeast and East Asia.We have demonstrated the combined ROTI maps to capture the development of ionospheric irregularities in the Southeast/East Asian sector during the G5 Geomagnetic Storm on May 11,2024.We observed simultaneous ionospheric irregularities in Japan and Australia,respectively propagating northwestward and southwestward,before midnight,whereas Southeast Asia’s equatorial and low-latitude regions exhibited irregularities post-midnight.By sharing ROTI maps from Indonesia and integrating them with regional GNSS networks,researchers can conduct comprehensive EPB studies,enhancing the understanding of EPB behavior across Southeast and East Asia and contributing significantly to ionospheric research.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
Unlike conventional spherical charges,a shaped charge generates not only a strong shock wave and a pulsating bubble,but also a high strain rate metal jet and a ballistic wave during the underwater explosion.They show ...Unlike conventional spherical charges,a shaped charge generates not only a strong shock wave and a pulsating bubble,but also a high strain rate metal jet and a ballistic wave during the underwater explosion.They show significant characteristic differences and couple each other.This paper designs and conducts experiments with shaped charges to analyze the complicated process.The effects of liner angle and weight of shaped charge on the characteristics of metal jets,waves,and bubbles are discussed.It is found that in underwater explosions,the shaped charge generates the metal jet accompanied by the ballistic wave.Then,the shock wave propagates and superimposes with the ballistic wave,and the generated bubble pulsates periodically.It is revealed that the maximum head velocity of the metal jet versus the liner angle a and length-to-diameter ratio k of the shaped charge follows the laws of 1/(α/180°)^(0.55)andλ^(0.16),respectively.The head shape and velocity of the metal jet determine the curvature and propagation speed of the initial ballistic wave,thus impacting the superposition time and region with the shock wave.Our findings also reveal that the metal jet carries away some explosion products,which hinders the bubble development,causing an inward depression of the bubble wall near the metal jet.Therefore,the maximum bubble radius and pulsation period are 5.2%and 3.9%smaller than the spherical charge with the same weight.In addition,the uneven axial energy distribution of the shaped charge leads to an oblique bubble jet formation.展开更多
In recent years,the phenomenon of multistability has attracted wide attention.In this paper,a memristive chaotic system with extreme multistability is constructed by using a memristor.The dynamic behavior of the syste...In recent years,the phenomenon of multistability has attracted wide attention.In this paper,a memristive chaotic system with extreme multistability is constructed by using a memristor.The dynamic behavior of the system is analyzed by Poincar´e mapping,a time series diagram,and a bifurcation diagram.The results show that the new system has several significant characteristics.First,the new system has a constant Lyapunov exponent,transient chaos and one complete Feigenbaum tree.Second,the system has the phenomenon of bifurcation map shifts that depend on the initial conditions.In addition,we find periodic bursting oscillations,chaotic bursting oscillations,and the transition of chaotic bursting oscillations to periodic bursting oscillations.In particular,when the system parameters take different discrete values,the system generates a bubble phenomenon that varies with the initial conditions,and this bubble can be shifted with the initial values,which has rarely been seen in the previous literature.The implementation by field-programmable gate array(FPGA)and analog circuit simulation show close alignment with the MATLAB numerical simulation results,validating the system’s realizability.Additionally,the image encryption algorithm integrating DNA-based encoding and chaotic systems further demonstrates its practical applicability.展开更多
基金Supported by the Natural Science Foundation of Shandong Province(No.ZR2022MD074)the Laboratory for Marine Mineral Resources+3 种基金Qingdao National Laboratory for Marine Science and Technology(No.MMRKF201810)the National Natural Science Foundation of China(No.41606077)the National Key R&D Program of China:HighPrecision Characterization Technology of Gas Hydrate Reservoir(No.2017YFC0307406-03)supported by the Shandong Province Taishan Scholar Construction Project。
文摘Submarine seep plumes are a natural phenomenon in which different types of gases migrate through deep or shallow subsurface sediments and leak into seawater in pressure gradient.When detected using acoustic data,the leaked gases frequently exhibit a flame-like structure.We numerically modelled the relationship between the seismic response characteristic and bubble volume fraction to establish the bubble volume fraction in the submarine seep plume.Results show that our models are able to invert and predict the bubble volume fraction from field seismic oceanography data,by which synthetic seismic sections in different dominant frequencies could be numerically simulated,seismic attribute sections(e.g.,instantaneous amplitude,instantaneous frequency,and instantaneous phase)extracted,and the correlation between the seismic attributes and bubble volume fraction be quantitatively determined with functional equations.The instantaneous amplitude is positively correlated with bubble volume fraction,while the instantaneous frequency and bubble volume fraction are negatively correlated.In addition,information entropy is introduced as a proxy to quantify the relationship between the instantaneous phase and bubble volume fraction.As the bubble volume fraction increases,the information entropy of the instantaneous phase increases rapidly at the beginning,followed by a slight upward trend,and finally stabilizes.Therefore,under optimal noise conditions,the bubble volume fraction of submarine seep plumes can be inverted and predicted based on seismic response characteristics in terms of seismic attributes.
基金supported by the National Natural Science Foundation of China(Nos.61372143 and 61671321)
文摘This paper presents a new three-dimensional(3D) volume measurement approach of bubble in gas-liquid two-phase flow. According to the dual perspective imaging principle,bubble feature images can be captured from two different view angles. The least square ellipse fitting algorithm is used to figure out the feature parameters from the captured images. Then the 3D volume of bubble can be quantitatively measured. Compaerd with the traditional volume estimation methods based on single perspective imaging,it can effectively reduce the loss of bubble feature information. In the experiment,the 3D volume reconstruction of bubbles from dual perspective images is conducted,and the variation of bubble volume in the bubble rising process is studied. The results show that the measurement accuracy based on the proposed 3D method is higher than those based on traditional methods. The volume of rising bubble is periodically changed,which indicates that bubble achieves periodic rotation and deformation in the rising process.
基金support from the Chinese Scholarship Council(Grant No.2022GXZ005733)。
文摘The Pressure-Volume-Temperature(PVT)properties of crude oil are typically determined through laboratory analysis during the early phases of exploration and fielddevelopment.However,due to extensive data required,time-consuming nature,and high costs,laboratory methods are often not preferred.Machine learning,with its efficiencyand rapid convergence,has emerged as a promising alternative for PVT properties estimation.This study employs the modified particle swarm optimization-based group method of data handling(PSO-GMDH)to develop predictive models for estimating both the oil formation volume factor(OFVF)and bubble point pressure(P_(b)).Data from the Mpyo oil fieldin Uganda were used to create the models.The input parameters included solution gas-oil ratio(R_(s)),oil American Petroleum Institute gravity(API),specificgravity(SG),and reservoir temperature(T).The results demonstrated that PSO-GMDH outperformed backpropagation neural networks(BPNN)and radial basis function neural networks(RBFNN),achieving higher correlation coefficientsand lower prediction errors during training and testing.For OFVF prediction,PSO-GMDH yielded a correlation coefficient(R)of 0.9979(training)and 0.9876(testing),with corresponding root mean square error(RMSE)values of 0.0021 and 0.0099,and mean absolute error(MAE)values of 0.00055 and 0.00256,respectively.For P_(b)prediction,R was 0.9994(training)and 0.9876(testing),with RMSE values of 6.08 and 8.26,and MAE values of 1.35 and 2.63.The study also revealed that R_(s)significantlyimpacts OFVF and P_(b)predictions compared to other input parameters.The models followed physical laws and remained stable,demonstrating that PSO-GMDH is a robust and efficientmethod for predicting OFVF and P_(b),offering a time and cost-effective alternative.
基金Supported by the National Natural Science Foundation of China(Grant No.52271319)the Jiangsu Funding Program for Excellent Postdoctoral Talent,and the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant No.GZC20240618)the Natural Science Foundation of Jiangsu Province of China(BK20231525).
文摘In this study,the dynamic characteristics of microscale floating bubbles near the vertical wall are studied.This occurrence is common in industrial and natural phenomena.Although many studies have been conducted on microscale bubbles,few studies investigate floating bubbles with very small Reynolds number(Re)near the wall,which is the main research goal of this study.Therefore,this study establishes a model for the ascent of small-scale bubbles near a vertical wall using the interFoam solver in OpenFOAM.This study investigates the influences of diverse viscosity parameters,varying distances from the wall,and different gas flow rates on the terminal velocity,deformation,and motion trajectory of bubbles.The results reveal that as liquid viscosity increases,the Re of bubbles gradually decreases and reaches a minimum of 0.012,which is similar to the Re of micrometer-sized bubbles in water.The characteristics of the wall-induced force in the longitudinal direction are closely related to the changes in liquid viscosity.Under low-viscosity conditions,the induced lift is the principal form of action,whereas under high-viscosity conditions,it is primarily manifested as induced drag.
基金the Scientific Research Projects Unit of Erciyes University under contract no:FDS-2022-11532 and FOA-2025-14773.
文摘This paper examines a model that combines vortex generators and leading-edge tubercles for controlling the laminar separation bubble(LSB)over an airfoil at low Reynolds numbers(Re).This new concept of passive flow control technique utilizing a tubercle and vortex generator(VG)close to the leading edge was analyzed numerically for a NACA0015 airfoil.In this study,the Shear Stress Transport(SST)turbulence model was employed in the numerical modelling.Numerical modelling was completed using the ANSYS-Fluent 18.2 solver.Analyses were conducted to investigate the flow pattern and understand the underlying LSB control phenomena that enabled the new passive flow control method to provide this significant performance benefit.The findings indicated that the new concept of passive flow control technique suppressed the formation of an LSB at the suction surface of the NACA0015 airfoil,resulting in a higher lift coefficient and improved aerodynamic performance.Improvements in LSB dynamics and aerodynamic performance through the passive flow control method lead to increased energy output and enhanced stability.
基金supported by the National Natural Science Foundation of China(Grant No.52374317).
文摘Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath dynamics.A physical model and a 3D gas-slag-steel transient bottom-blowing numerical model of a 150 t EAF were established to investigate the bubble behaviour and flow characteristics throughout the molten steel bath and slag layer under bottom-blowing,with referring to gas flow rate,plug diameter,plug arrangement and injection angle.Results indicate that the average bubble sizes experience increase,dynamic stability and decrease in molten steel bath and then undergo decrease and increase after entering into slag layer for all bottom-blowing modes.The bubble numbers exhibit the opposing trends during the process.Increase in gas flow rate leads to a significant rise in average bubble size but a decrease in number,average dwelling time and the spread area of bubbles in slag layer.Increase in plug diameter causes an opposite impact.The effect of plug arrangement radii on bubbles is almost negligible.Increasing the injection angle results in an increase in bubble size and a decrease in both bubble number and dwelling time in slag layer.The slag foaming potential was discussed referring to the bubble size,number and dwelling time in slag layer.Increase in gas flow rate and plug diameters can significantly enhance the fluids flow through increasing average flow velocity,decreasing mixing time and dead zone ratio of molten bath.Plug arrangement radius and injection angle express nonlinear correlation with average flow velocity and dead zone ratio,and the plug arrangement radius of 0.5R(R represents the radius of bottom circle of EAF model)and injection angle of 15°perform better in enhancing dynamics of molten bath.A group of bottom-blowing parameters are proposed to achieve better comprehensive performance of bubble-induced slag foaming and molten bath dynamics.
基金supported by the National Natural Science Foundation of China(Nos.U22B2067 and 52073176).
文摘350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by annealing at 750℃ for 10,100,and 300 h,respectively.The results showed that material swelling due to helium bubble coarsening was almost not observed in either the LPBF or rolled samples after 10 h of annealing duration.Rapid coarsening and swelling of bubbles occurred in the rolled samples,but only moderate bubble growth occurred in the LPBF sample after annealing for 100 h.After annealing for 300 h,the helium bubbles in both samples tended to grow steadily.For 10 h of annealing,the irradiated samples were in a disequilibrium state,and the apparent activation energy(E^(act))calculated by the Arrhenius model determined that helium atoms tended to diffuse through the displacement mechanism,and helium bubbles grew under the migration and coalescence(MC)mechanism.With annealing times over 100 h,the high-density dislocations and nano-oxide particles in the LPBF sample still had a strong trapping effect on the movement and growth of helium bubbles.After annealing for 300 h,the cellular subgrains in the LPBF sample decomposed,and the nano-oxide particles had no trapping effect on the helium bubbles.At this time,the dislocation structure played a primary role in suppressing the growth of helium bubbles,and the radiation resistance of the LPBF sample remained superior to that of the rolled samples.
基金supported by a grant from China railway corporation science and technology research and development plan project(Grant No.2017G005-B)funding support by Wuyi University’s Hong Kong and Macao Joint Research and Development Fund(Grants No.2021WGALH15)funding support by the Innovation and Technology Commission of Hong Kong SAR Government to the Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center(Grant No.K-BBY1).
文摘The current technical standards primarily relied on experience to judge the interfacial bonding properties between the self-compacting concrete filling layer and the steam-cured concrete precast slab in CRTS Ⅲ slab ballastless track structure.This study sought to enhance technical standards for evaluating interfacial bonding properties by suggesting the use of the splitting tensile strength to evaluate the impact of bubble defects.Specimens were fabricated through on-site experiment.The percent of each area of 6 cm^(2)or more bubble defect was 0 in most of specimens.When the cumulative area of all bub-ble defects reached 12%,the splitting tensile strength value was 0.67 MPa,which exceeded the minimum required value of 0.5 MPa for ensuring bonding interface adhesion.Furthermore,when the cumulative area of all bubble defects reached 8%,the splitting tensile strength value was 0.85 MPa,which exceeded the minimum required value of 0.8 MPa,thereby over-coming the negative impact of each area of 10 cm^(2) or more bubble defect.Additionally,keeping the cumulative area of each area of 6 cm^(2) or more bubble defect below 6%ensured adequate bonding strength and reduced the occurrence of specimens with lower splitting tensile strength values.
基金the Natural Science Foundation of China(Project for Young Scientists:Grant No.52105010,Regular Project:Grant No.62173096)Natural Science Foundationof Guangdong Province(Regular Project:Grant No.2025A1515012124,Grant No.2022A1515010327)Guangdong-Hong Kong-Macao Key Laboratory of Multi-scaleInformation Fusion and Collaborative Optimization Control Manufacturing Process.
文摘Legged robots have considerable potential for traversing unstructured situations;nonetheless,their inflexible frameworks often constrain adaptability and obstacle negotiation.The study article presents a revolutionary Soft Tri-Legged Robot(STLR)that improves movement and obstacle-avoidance skills by using a bio-inspired pneumatic artificial muscle(Bubble Artificial Muscles)and a bio-inspired tactile sensor(TacTip).The STLR is activated by BAMs,which are flexible,pneu-matic-driven actuators that provide fine control over forward,backward,and steering movements.Obstacle identification and avoidance are facilitated by the TacTip sensor,which delivers tactile input for traversing unstructured terrains.We delineate the mechanical features of the BAMs,assess the functionality of the robot's legs,and elaborate on the incorpora-tion of the tactile sensing system.Experimental results demonstrate that the STLR can effectively achieve multi-directional flexible movement and obstacle avoidance through a cross-modal perception-actuation mechanism.This study highlights the promise of soft robotics for search and rescue,medical aid,and autonomous exploration,while delineating difficulties and opportunities for future improvements in functionality and efficiency.
基金supported by the National Natural Science Foundation of China(Grant No.12172063).
文摘The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.
基金Supported by the National Ministry of Science and Technology of China(2017YFB0602401)the National Natural Science Foundation of China(21776173,91834303,U1862201,21625603)the Program of Shanghai Subject Chief Scientists(18XD1402000).
文摘This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble column reactor was simulated. The grid independence study was first conducted and a grid size of 1.0 mm was adopted in order to minimize the computing time without compromising the accuracy of the results. The predictions were validated by comparing the experimental studies reported in the literature. It was found that all surface tension models can describe the bubble rise and bubble plume in a column with slight deviations.
基金The support of National Nature Science Foundation of China(No.51276192)No.61338 for the National Basic Research Program of Chinathe Innovative Research Project of Xi’an Hi-tech Institute(EPXY0806)are gratefully acknowledged.
文摘A coupled method describing gas–solid two-phase flow has been proposed to numerically study the bubble formation at a single orifice in gas-fluidized beds.Solid particles are traced with smoothed particle hydrodynamics,whereas gas phase is discretized by finite volume method.Drag force,gas pressure gradient,and volume fraction are used to couple the two methods.The effect of injection velocities,particle sizes,and particle densities on bubble growth is analyzed using the coupled method.The simulation results,obtained for two-dimensional geometries,include the shape and diameter size of a bubble as a function of time;such results are compared with experimental data,previous numerical results,and other approximate model predictions reported in the literature.Moreover,the flow profiles of gas and particle phases and the temperature distribution by the heat transfer model around the forming bubble are also discussed.All results show that the coupled method efficiently describes of the bubble formation in fluidized beds.The proposed method is applicable for solving gas–solid two-phase flow in fluidization.
基金Supported by the National Natural Science Foundation of China(50776063)the Natural Science Foundation of Tianjin(11JCZDJC22500)
文摘In order to address the bubble formation and movement in air-water two-phase flow,single bubble rising in stagnant water is experimentally studied by digital image processing.Bubbles are released individually from the submerged orifices with different diameters(1.81 mm,2.07 mm,2.98 mm,3.92 mm)at different detachment frequency.Images are recorded by a high-speed video camera and processed by digital image processing technique. The factors impacting the formed volume of bubble are discussed.The experimental results showed that a threshold of gas flow rate(400 mm 3 ·s- 1)divides the bubble formation into two regimes:the constant volume regime and the growing volume regime.Especially for the growing volume regime,the surface tension is taken into account.The bubble volume is consisted of two parts:the surface tension impacting part and the gas volume flow rate impacting part.An improved correlation for bubble volume prediction is developed for the two regimes and better coincidence with the experiment data than the previous models is obtained.
基金Supported by the Fundamental Research Funds for the Central Universities(HEUCFM181203)
文摘The multi-orifice plate gas sparger, mainly composed of a multi-orifice plate and a gas chamber, is one of the most common sparger facilities.The aeration performance of multi-orifice plate has a close relation with the multiorifice plate configuration.In addition, the weeping phenomenon has a considerable influence on the gas chamber condition which affects the bubble detachment volume directly.This paper conducts a set of visual experiments to study the influence of multi-orifice configuration and gas chamber condition on the aeration performance of gas sparger.For multi-orifice plate, an improved theoretical model is proposed which considers the wave effect of the previous bubbles generated from adjacent orifices and the variance of the number of active bubbling orifice.A parameter is proposed to evaluate the aeration performance in order to overcome the difficulty caused by the randomness of bubble formation process.The experimental results suggest that the gas chamber filled with water is in favor of large bubble formation.The influence of the pitch of orifice on aeration performance can only be observed in high-restricted case.According to the theoretical model and experimental results, the influences of gas flow rate and the number of open orifices on the aeration performance are analyzed and a design criterion for the number of open orifice is proposed.
基金supported by the National Natural Science Foundation of China(Grant No.52104321)the Natural Science Foundation of Chongqing,China(Grant No.CSTB2023NSCQ-MSX0871)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202101404).
文摘Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure drop.Additional simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,respectively.The simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be reached.The primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic pressure.When the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,respectively.The bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.
基金Supported by the Program for New Century Excellent Talents in University in China(No NCET-07-0685).
文摘Mechanisms for the evolution of a single spherical bubble subjected to sound excitation in water are studied from the viewpoint of nonlinear dynamics.First,the shooting method is combined with a Poincaré map to obtain the fixed point for the case of forced oscillation in volume.Then,the stabilities are judged by Floquet theory and the bifurcation theorem.Moreover,the transitions of bubble oscillation in volume due to sound excitation in water are explained from the viewpoint of nonlinear dynamics in detail.The results show that with an increase in sound frequency,the period-1 oscillation becomes unstable,and oscillation behaves in a double-periodic manner,then a quasi-periodic manner,and finally chaotically.Additionally,with an increase of the amplitude of the sound pressure,the bubble eventually oscillates with chaos via a series of period-doubling bifurcations.
基金JSPS KAKENHI Grant Number16H06286 supports global GNSS ionospheric maps (TEC,ROTI,and detrended TEC maps) developed by the Institute for SpaceEarth Environmental Research (ISEE) of Nagoya Universitysupport of the 2024 JASSO Follow-up Research Fellowship Program for a 90-day visiting research at the Institute for Space-Earth Environmental Research (ISEE),Nagoya University+3 种基金the support received from Telkom University under the“Skema Penelitian Terapan Periode I Tahun Anggaran 2024”the Memorandum of Understanding for Research Collaboration on Regional Ionospheric Observation (No:092/SAM3/TE-DEK/2021)the National Institute of Information and Communications Technology (NICT) International Exchange Program 2024-2025(No.2024-007)support for a one-year visiting research at Hokkaido University
文摘This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signals and degrade positioning accuracy.Managed by the Indonesian Geospatial Information Agency(BIG),the Indonesia Continuously Operating Reference Station(Ina-CORS)network comprises over 300 GNSS receivers spanning equatorial to southern low-latitude regions.Ina-CORS is uniquely situated to monitor EPB generation,zonal drift,and dissipation across Southeast Asia.We provide a practical tool for EPB research,by sharing two-dimensional rate of Total Electron Content(TEC)change index(ROTI)derived from this network.We generate ROTI maps with a 10-minute resolution,and samples from May 2024 are publicly available for further scientific research.Two preliminary findings from the ROTI maps of Ina-CORS are noteworthy.First,the Ina-CORS ROTI maps reveal that the irregularities within a broader EPB structure persist longer,increasing the potential for these irregularities to migrate farther eastward.Second,we demonstrate that combined ROTI maps from Ina-CORS and GNSS receivers in East Asia and Australia can be used to monitor the development of ionospheric irregularities in Southeast and East Asia.We have demonstrated the combined ROTI maps to capture the development of ionospheric irregularities in the Southeast/East Asian sector during the G5 Geomagnetic Storm on May 11,2024.We observed simultaneous ionospheric irregularities in Japan and Australia,respectively propagating northwestward and southwestward,before midnight,whereas Southeast Asia’s equatorial and low-latitude regions exhibited irregularities post-midnight.By sharing ROTI maps from Indonesia and integrating them with regional GNSS networks,researchers can conduct comprehensive EPB studies,enhancing the understanding of EPB behavior across Southeast and East Asia and contributing significantly to ionospheric research.
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funded by the National Natural Science Founda-tion of China(52071109).
文摘Unlike conventional spherical charges,a shaped charge generates not only a strong shock wave and a pulsating bubble,but also a high strain rate metal jet and a ballistic wave during the underwater explosion.They show significant characteristic differences and couple each other.This paper designs and conducts experiments with shaped charges to analyze the complicated process.The effects of liner angle and weight of shaped charge on the characteristics of metal jets,waves,and bubbles are discussed.It is found that in underwater explosions,the shaped charge generates the metal jet accompanied by the ballistic wave.Then,the shock wave propagates and superimposes with the ballistic wave,and the generated bubble pulsates periodically.It is revealed that the maximum head velocity of the metal jet versus the liner angle a and length-to-diameter ratio k of the shaped charge follows the laws of 1/(α/180°)^(0.55)andλ^(0.16),respectively.The head shape and velocity of the metal jet determine the curvature and propagation speed of the initial ballistic wave,thus impacting the superposition time and region with the shock wave.Our findings also reveal that the metal jet carries away some explosion products,which hinders the bubble development,causing an inward depression of the bubble wall near the metal jet.Therefore,the maximum bubble radius and pulsation period are 5.2%and 3.9%smaller than the spherical charge with the same weight.In addition,the uneven axial energy distribution of the shaped charge leads to an oblique bubble jet formation.
基金Project supported by the Natural Science Foundation of Hubei Province(Grant No.2024AFD068).
文摘In recent years,the phenomenon of multistability has attracted wide attention.In this paper,a memristive chaotic system with extreme multistability is constructed by using a memristor.The dynamic behavior of the system is analyzed by Poincar´e mapping,a time series diagram,and a bifurcation diagram.The results show that the new system has several significant characteristics.First,the new system has a constant Lyapunov exponent,transient chaos and one complete Feigenbaum tree.Second,the system has the phenomenon of bifurcation map shifts that depend on the initial conditions.In addition,we find periodic bursting oscillations,chaotic bursting oscillations,and the transition of chaotic bursting oscillations to periodic bursting oscillations.In particular,when the system parameters take different discrete values,the system generates a bubble phenomenon that varies with the initial conditions,and this bubble can be shifted with the initial values,which has rarely been seen in the previous literature.The implementation by field-programmable gate array(FPGA)and analog circuit simulation show close alignment with the MATLAB numerical simulation results,validating the system’s realizability.Additionally,the image encryption algorithm integrating DNA-based encoding and chaotic systems further demonstrates its practical applicability.
