In the framework of elastoplastic theory,by introducing dissipative plastic energy(instead of cumulative plastic strain)and dissipative plastic energy rate(instead of cumulative plastic strain rate)into the ratchettin...In the framework of elastoplastic theory,by introducing dissipative plastic energy(instead of cumulative plastic strain)and dissipative plastic energy rate(instead of cumulative plastic strain rate)into the ratchetting parameter evolution equation and isotropic evolution rules respectively,a cyclic elastoplastic constitutive model based on dissipative plastic energy is established.This model,termed the WDP model,describes the physical meaning and evolution rule of the unclosed stress–strain hysteresis loop using an energy method.A comparison of numerical implementation results with experimental data demonstrates the capability of the WDP model to predict the cyclic deformation of EA4T steel,effectively capturing the cyclic softening characteristics and ratchetting behaviors of axle steel EA4T.展开更多
This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These model...This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These models offer valuable insights into nonlinear wave propagation,with applications in fluid dynamics and materials science,including systems such as liquid crystals and ferrofluids.It is shown that the conservative Sawada-Kotera equation supports traveling wave solutions corresponding to elliptic limit cycles,as well as two-and three-dimensional invariant tori surrounding these cycles in the associated ordinary differential equation(ODE)system.For the dissipative generalized Sawada-Kotera equation,chaotic wave behavior is observed.The transition to chaos in the corresponding ODE systemfollows a universal bifurcation scenario consistent with the framework established by FShM(Feigenbaum-Sharkovsky-Magnitskii)theory.Notably,this study demonstrates for the first time that the conservative Sawada-Kotera equation can exhibit complex quasi-periodic wave solutions,while its dissipative counterpart admits an infinite number of stable periodic and chaotic waveforms.展开更多
Erratum to:https://doi.org/10.1007/s 00343-024-4040-x In this article,the Fig.2 b contained a few mistakes.The figure below shows the wrong on e.The figure should have appeared as shown below.
In this study,a novel observer-based scalable control scheme for large-scale systems(LSSs)with several interconnected subsystems is explored.Firstly,a scalable observer-based controller is designed to address complex ...In this study,a novel observer-based scalable control scheme for large-scale systems(LSSs)with several interconnected subsystems is explored.Firstly,a scalable observer-based controller is designed to address complex situations where system states are difficult to measure directly.Secondly,unlike the limited cascade and ring topology connections in previous results,this study considers a universal arbitrary topology.Furthermore,it is noteworthy that the plug-and-play(PnP)capability of LSSs is guaranteed thanks to the proposed scalable scheme.Specifically,when subsystems are added or removed,only the controller gains of directly connected neighbors need updating,eliminating the need to redesign the entire system.Moreover,by choosing a Lyapunov-Krasovskii function with a quadratic matrix-valued polynomial,sufficient conditions are deduced to guarantee the global exponential stability with the desired extended dissipative performance for the resulting LSSs.Finally,the effectiveness of the employed scheme is verified by numerical and microgrid examples.展开更多
Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady ...Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.展开更多
This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro...This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro cantilever channel,aiming to deepen our understanding of heat transport processes in complex fluid dynamics scenarios.The primary objective is to elucidate how physical operational parameters influence both the velocity of fluid flow and its temperature distribution,utilizing a comprehensive numerical approach.Employing a combination of mathematical modeling techniques,including similarity transformation,this investigation transforms complex partial differential equations into more manageable ordinary ones,subsequently solving them using the homotopy perturbation method.By analyzing the obtained solutions and presenting them graphically,alongside detailed analysis,the study sheds light on the pivotal role of significant parameters in shaping fluid movement and energy distribution.Noteworthy observations reveal a substantial increase in fluid velocity with escalating magnetic parameters,while conversely,a contrasting trend emerges in the temperature distribution,highlighting the intricate relationship between magnetic effects,flow dynamics,and thermal behavior in non-Newtonian fluids.Further,the suction velocity enhance both the local skin friction and Nusselt numbers,whereas theWeissenberg number reduces them,opposite to the effect of the power-law index.展开更多
Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus ...Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus edulis foot protein-1(Mefp-1)has been identified as the most abundant protein.It has been found that lipids are involved in the mussel adhesion process and can facilitate Mefp-1adhesion.In this research,the adhesion behavior of Mefp-1 on various substrate surfaces under the effect of typical seawater cations with or without the presence of lipid were investigated using a quartz crystal microbalance with dissipation(QCM-D).Results indicate that the presence of cations Ca^(2+),Mg^(2+),Na^(+),and K^(+)leads to varying degrees of reduction in the adhesion performance of Mefp-1 on different substrates.The degree of this reduction,however,was much alleviated in the presence of palmitic acid,which is involved in the mussel adhesion process.Therefore,the involvement of palmitic acid is advantageous for mussel protein adhesion to the substrate surface in the marine environment.This study illustrated the significant contribution of palmitic acid to mussel adhesion,which can help to better understand biofouling mechanisms and develop biomimetic adhesive materials.展开更多
The microphase-separating behaviors of two types of star-diblock copolymers （Ax）4（By）4 and （A^Bg）4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered ...The microphase-separating behaviors of two types of star-diblock copolymers （Ax）4（By）4 and （A^Bg）4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered mesostructures have been observed and the simulated phase diagrams show obvious symmetries for the （Ax）4（By）a films and asymmetries for the （AxBy）4 films, besides, it is easier for the （Ax）4（By）4 than for the （A^By）4 to carry out microphase separation under the same conditions, which has been recognized in bulk and can be ascribed to the structural difference between the two types of star copolymers. There are some correspondences between the mesostructures formed in the film and those formed in bulk at the same composition fraction. Decreasing the thickness of film and strengthening the A-B repulsion both help the mesostructures enhance the degree of order. Composition fraction dependences of the mean-square radius of gyration in the two types of star copolymer films are almost contrary, which can be attributed to the differences in their respective structures. These findings can provide a guide to designing novel microstructures involving star-diblock copolymers via geometrical confinement.展开更多
Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any pr...Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any property separately with the thickness of film, the interaction between particles of different types, the repulsion between particle and boundary, except for the dependence of the variations of mean-square bond length on the thickness of film, which exhibits as a wave trend. What＇s more, the varying trends of mean-square bond length and root-mean-square end-to-end distance can correspond to each other. The density distribution of either component in diblock copolymer film can be controlled and adjusted effectively through its interaction with boundary.展开更多
This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coeffic...This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. Based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. From basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.展开更多
This paper focused on a class of linear state-delayed systems with or without uncertainty. As for uncertain systems, dissipative uncertainty description contains norm-bounded and positive real uncertainties as special...This paper focused on a class of linear state-delayed systems with or without uncertainty. As for uncertain systems, dissipative uncertainty description contains norm-bounded and positive real uncertainties as special cases. The paper is concerned with the design of dissipative static state feedback controllers such that the closed-loop system is (robustly) asymptotically stable and strictly (Q,S,R)-dissipative. Sufficient conditions for the existence of the quadratic dissipative state feedback controllers are obtained by using a linear matrix inequality (LMI) approach. It is shown that the solvability of dissipative controller design problem is implied by the feasibility of LMIs. The main results of this paper unify the existing results on H ∞ control and passive control.展开更多
In a biased dissipative photovoltaic-photorefractive system, this paper investigates the temperature effect on the evolution and the self-deflection of the dissipative holographic screening-photovoltaic （DHSP） solit...In a biased dissipative photovoltaic-photorefractive system, this paper investigates the temperature effect on the evolution and the self-deflection of the dissipative holographic screening-photovoltaic （DHSP） solitons. The results reveal that, the evolution and the self-deflection of the bright and dark DHSP solitons are influenced by the system temperature. At a given temperature, for a stable DHSP soliton originally formed in the dissipative system, it attempts to evolve into another DHSP soliton when the temperature change is appropriately small, whereas it will become unstable or break down if the temperature departure is large enough. Moreover, the self-deflection degree of the solitary beam centre increases as temperature rises in some range, while it is decided by the system parameters and is slight under small-signal condition. The system temperature can be adjusted to change the formation and the self-deflection of the solitary beam in order to gain certain optical ends. In a word, the system temperature plays a role for the DHSP solitons in the dissipative system.展开更多
The quantum fluctuations of the charge and current in a non-dissipative mesoscopic circuit with coupled inductors and capacitors are studied for the squeezed vacuum state.The influence of the phase angle upon the quan...The quantum fluctuations of the charge and current in a non-dissipative mesoscopic circuit with coupled inductors and capacitors are studied for the squeezed vacuum state.The influence of the phase angle upon the quantum fluctuations is discussed in particular.Our results indicate that when the circuit parameters remain constant and the phasesθof the two circuits are equal,the squeezing of the charge or its conjugate variable increases.When the difference of the two phases equalsπ,the squeezing will deteriorate.Therefore,if we want to decrease the quantum noise,we should not only control the amplitude r,but also control the phaseθcarefully.展开更多
We study the quantum fluctuations of the charge and current of two L-C dissipative mesoscopic circuit with the mutual inductance in the vacuum state.Our results show that the system state will evolve to a squeezed coh...We study the quantum fluctuations of the charge and current of two L-C dissipative mesoscopic circuit with the mutual inductance in the vacuum state.Our results show that the system state will evolve to a squeezed coherent state under the effect of external source.We find that the squeezing amplitude parameter is relative to the parameters of circuit and the mutual-inductance coefficient in the existence of dissipation.When the circuit has no dissipation or there is complete coupling between two meshes,the squeezing amplitude parameter only depends on the capacitance's ratio.展开更多
The phenomenological flow theory of higher-order strain gradient plasticity proposed by Fleck and Hutchinson(J.Mech.Phys.Solids,2001)and then improved by Fleck and Willis(J.Mech.Phys.Solids,2009)is used to investigate...The phenomenological flow theory of higher-order strain gradient plasticity proposed by Fleck and Hutchinson(J.Mech.Phys.Solids,2001)and then improved by Fleck and Willis(J.Mech.Phys.Solids,2009)is used to investigate the surface-passivation problem and micro-scale plasticity.An extremum principle is stated for the theory involving one material length scale.To solve the initial boundary value problem,a numerical scheme based on the framework of variational constitutive updates is developed for the strain gradient plasticity theory.The main idea is that,in each incremental time step,the value of the effective plastic strain is obtained through the variation of a functional in regard to effective plastic strain,provided the displacement or deformation gradient.Numerical results for elasto-plastic foils under tension and bending,thin wires under torsion,are given by using the minimum principle and the numerical scheme.Implications for the role of dissipative gradient effect are explored for three non-proportional loading conditions:(1)stretch-passivation problem,(2)bending-passivation problem,and(3)torsion-passivation problem.The results indicate that,within the Fleck-Hutchinson-Willis theory,the dissipative length scale controls the strengthening size effect,i.e.the increase of initial yielding strength,while the surface passivation gives rise to an increase of strain hardening rate.展开更多
Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,producti...Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,productivity and passenger comfort in case of vehicle applications.Dissipative elastic metamaterials have caught considerable attention of scientific community due to their effective medium properties and peculiar dynamic characteristics including frequency bandgaps that can be effectively applied to attenuate and control undesirable vibration and noises.Although a substantial amount of theoretical work for effective medium characteristics and dynamic properties of acoustic/elastic metamaterials has been reported,the practical design and application of these composite structures for real-life engineering problems still remain unexplored.The present study intends to investigate a potential application of dissipative elastic metamaterials in controlling the bearing-generated vibration and noises over an ultrawide frequency range.The study is based on a simple analytical model together with rigorous finite element numerical simulations.It has been established that the dissipative characteristic of resonant system caused by larger material mismatch broadens the local resonance bandgaps beyond the bounding resonance frequency at the cost of wave transmission.In order to achieve broadband vibration and noise control,multi-resonant composite structures are embedded inside the bearing housing in five different layers.The reported results revealed the presence of broadband wave attenuation zone distributed from 3 to 52 kHz with consideration of material damping.The bearing-generated vibration and noises lying inside the wave attenuation zone will be mitigated.This feasibility study provides a new concept for the design and application of acoustic/elastic metamaterials in the bearing industry to improve machine service life and to enhance productivity and passenger comfort.展开更多
Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. Thes...Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.展开更多
A fully discrete finite difference scheme for dissipative Zakharov equations is analyzed. On the basis of a series of the time-uniform priori estimates of the difference solutions, the stability of the difference sche...A fully discrete finite difference scheme for dissipative Zakharov equations is analyzed. On the basis of a series of the time-uniform priori estimates of the difference solutions, the stability of the difference scheme and the error bounds of optimal order of the difference solutions are obtained in L^2 × H^1 × H^2 over a finite time interval （0, T]. Finally, the existence of a global attractor is proved for a discrete dynamical system associated with the fully discrete finite difference scheme.展开更多
This paper is concerned with the existence and the nonlinear asymptotic stabil- ity of traveling wave solutions to the Cauchy problem for a system of dissipative evolution equations {θt=vζx＋（ζθ）x＋aθxx,ζt=-θ...This paper is concerned with the existence and the nonlinear asymptotic stabil- ity of traveling wave solutions to the Cauchy problem for a system of dissipative evolution equations {θt=vζx＋（ζθ）x＋aθxx,ζt=-θx＋βζxx;with initial data and end states （ζθ）（x,0）=（ζ0,θ0）（x）→（ζ±,θ±）as x→∞.We obtain the existence of traveling wave solutions by phase plane analysis and show the asymptotic nonlinear stability of traveling wave solutions without restrictions on the coeffi- cients a and v by the method of energy estimates.展开更多
Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and...Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and the dinuclear system lifetimes of the order of 10^(-21 ) s have been deduced by analysing the cross section Auctuations.展开更多
基金supported by the Science&Technology Development Fund of Tianjin Education Commission for Higher Education(No.2023KJ250).
文摘In the framework of elastoplastic theory,by introducing dissipative plastic energy(instead of cumulative plastic strain)and dissipative plastic energy rate(instead of cumulative plastic strain rate)into the ratchetting parameter evolution equation and isotropic evolution rules respectively,a cyclic elastoplastic constitutive model based on dissipative plastic energy is established.This model,termed the WDP model,describes the physical meaning and evolution rule of the unclosed stress–strain hysteresis loop using an energy method.A comparison of numerical implementation results with experimental data demonstrates the capability of the WDP model to predict the cyclic deformation of EA4T steel,effectively capturing the cyclic softening characteristics and ratchetting behaviors of axle steel EA4T.
文摘This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These models offer valuable insights into nonlinear wave propagation,with applications in fluid dynamics and materials science,including systems such as liquid crystals and ferrofluids.It is shown that the conservative Sawada-Kotera equation supports traveling wave solutions corresponding to elliptic limit cycles,as well as two-and three-dimensional invariant tori surrounding these cycles in the associated ordinary differential equation(ODE)system.For the dissipative generalized Sawada-Kotera equation,chaotic wave behavior is observed.The transition to chaos in the corresponding ODE systemfollows a universal bifurcation scenario consistent with the framework established by FShM(Feigenbaum-Sharkovsky-Magnitskii)theory.Notably,this study demonstrates for the first time that the conservative Sawada-Kotera equation can exhibit complex quasi-periodic wave solutions,while its dissipative counterpart admits an infinite number of stable periodic and chaotic waveforms.
文摘Erratum to:https://doi.org/10.1007/s 00343-024-4040-x In this article,the Fig.2 b contained a few mistakes.The figure below shows the wrong on e.The figure should have appeared as shown below.
基金supported in part by the National Natural Science Foundation of China(62173218).
文摘In this study,a novel observer-based scalable control scheme for large-scale systems(LSSs)with several interconnected subsystems is explored.Firstly,a scalable observer-based controller is designed to address complex situations where system states are difficult to measure directly.Secondly,unlike the limited cascade and ring topology connections in previous results,this study considers a universal arbitrary topology.Furthermore,it is noteworthy that the plug-and-play(PnP)capability of LSSs is guaranteed thanks to the proposed scalable scheme.Specifically,when subsystems are added or removed,only the controller gains of directly connected neighbors need updating,eliminating the need to redesign the entire system.Moreover,by choosing a Lyapunov-Krasovskii function with a quadratic matrix-valued polynomial,sufficient conditions are deduced to guarantee the global exponential stability with the desired extended dissipative performance for the resulting LSSs.Finally,the effectiveness of the employed scheme is verified by numerical and microgrid examples.
文摘Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.
文摘This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro cantilever channel,aiming to deepen our understanding of heat transport processes in complex fluid dynamics scenarios.The primary objective is to elucidate how physical operational parameters influence both the velocity of fluid flow and its temperature distribution,utilizing a comprehensive numerical approach.Employing a combination of mathematical modeling techniques,including similarity transformation,this investigation transforms complex partial differential equations into more manageable ordinary ones,subsequently solving them using the homotopy perturbation method.By analyzing the obtained solutions and presenting them graphically,alongside detailed analysis,the study sheds light on the pivotal role of significant parameters in shaping fluid movement and energy distribution.Noteworthy observations reveal a substantial increase in fluid velocity with escalating magnetic parameters,while conversely,a contrasting trend emerges in the temperature distribution,highlighting the intricate relationship between magnetic effects,flow dynamics,and thermal behavior in non-Newtonian fluids.Further,the suction velocity enhance both the local skin friction and Nusselt numbers,whereas theWeissenberg number reduces them,opposite to the effect of the power-law index.
基金Supported by the National Natural Science Foundation of China(No.41776177)the Qingdao Marine Science and Technology Pilot National Laboratory Fund(Nos.2016ASKJ14,QNLM2016ORP0403)。
文摘Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus edulis foot protein-1(Mefp-1)has been identified as the most abundant protein.It has been found that lipids are involved in the mussel adhesion process and can facilitate Mefp-1adhesion.In this research,the adhesion behavior of Mefp-1 on various substrate surfaces under the effect of typical seawater cations with or without the presence of lipid were investigated using a quartz crystal microbalance with dissipation(QCM-D).Results indicate that the presence of cations Ca^(2+),Mg^(2+),Na^(+),and K^(+)leads to varying degrees of reduction in the adhesion performance of Mefp-1 on different substrates.The degree of this reduction,however,was much alleviated in the presence of palmitic acid,which is involved in the mussel adhesion process.Therefore,the involvement of palmitic acid is advantageous for mussel protein adhesion to the substrate surface in the marine environment.This study illustrated the significant contribution of palmitic acid to mussel adhesion,which can help to better understand biofouling mechanisms and develop biomimetic adhesive materials.
文摘The microphase-separating behaviors of two types of star-diblock copolymers （Ax）4（By）4 and （A^Bg）4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered mesostructures have been observed and the simulated phase diagrams show obvious symmetries for the （Ax）4（By）a films and asymmetries for the （AxBy）4 films, besides, it is easier for the （Ax）4（By）4 than for the （A^By）4 to carry out microphase separation under the same conditions, which has been recognized in bulk and can be ascribed to the structural difference between the two types of star copolymers. There are some correspondences between the mesostructures formed in the film and those formed in bulk at the same composition fraction. Decreasing the thickness of film and strengthening the A-B repulsion both help the mesostructures enhance the degree of order. Composition fraction dependences of the mean-square radius of gyration in the two types of star copolymer films are almost contrary, which can be attributed to the differences in their respective structures. These findings can provide a guide to designing novel microstructures involving star-diblock copolymers via geometrical confinement.
文摘Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any property separately with the thickness of film, the interaction between particles of different types, the repulsion between particle and boundary, except for the dependence of the variations of mean-square bond length on the thickness of film, which exhibits as a wave trend. What＇s more, the varying trends of mean-square bond length and root-mean-square end-to-end distance can correspond to each other. The density distribution of either component in diblock copolymer film can be controlled and adjusted effectively through its interaction with boundary.
文摘This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. Based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. From basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.
文摘This paper focused on a class of linear state-delayed systems with or without uncertainty. As for uncertain systems, dissipative uncertainty description contains norm-bounded and positive real uncertainties as special cases. The paper is concerned with the design of dissipative static state feedback controllers such that the closed-loop system is (robustly) asymptotically stable and strictly (Q,S,R)-dissipative. Sufficient conditions for the existence of the quadratic dissipative state feedback controllers are obtained by using a linear matrix inequality (LMI) approach. It is shown that the solvability of dissipative controller design problem is implied by the feasibility of LMIs. The main results of this paper unify the existing results on H ∞ control and passive control.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10574051 and 10174025)
文摘In a biased dissipative photovoltaic-photorefractive system, this paper investigates the temperature effect on the evolution and the self-deflection of the dissipative holographic screening-photovoltaic （DHSP） solitons. The results reveal that, the evolution and the self-deflection of the bright and dark DHSP solitons are influenced by the system temperature. At a given temperature, for a stable DHSP soliton originally formed in the dissipative system, it attempts to evolve into another DHSP soliton when the temperature change is appropriately small, whereas it will become unstable or break down if the temperature departure is large enough. Moreover, the self-deflection degree of the solitary beam centre increases as temperature rises in some range, while it is decided by the system parameters and is slight under small-signal condition. The system temperature can be adjusted to change the formation and the self-deflection of the solitary beam in order to gain certain optical ends. In a word, the system temperature plays a role for the DHSP solitons in the dissipative system.
文摘The quantum fluctuations of the charge and current in a non-dissipative mesoscopic circuit with coupled inductors and capacitors are studied for the squeezed vacuum state.The influence of the phase angle upon the quantum fluctuations is discussed in particular.Our results indicate that when the circuit parameters remain constant and the phasesθof the two circuits are equal,the squeezing of the charge or its conjugate variable increases.When the difference of the two phases equalsπ,the squeezing will deteriorate.Therefore,if we want to decrease the quantum noise,we should not only control the amplitude r,but also control the phaseθcarefully.
文摘We study the quantum fluctuations of the charge and current of two L-C dissipative mesoscopic circuit with the mutual inductance in the vacuum state.Our results show that the system state will evolve to a squeezed coherent state under the effect of external source.We find that the squeezing amplitude parameter is relative to the parameters of circuit and the mutual-inductance coefficient in the existence of dissipation.When the circuit has no dissipation or there is complete coupling between two meshes,the squeezing amplitude parameter only depends on the capacitance's ratio.
基金supported by the National Natural Science Foundation of China(Grants 11702103 and 11972168)the Young Elite Scientist Sponsorship Program by CAST(Grant 2016QNRC001)the Fundamental Research Funds for the Central Universities(Grant HUST 2018KFYYXJJ008)。
文摘The phenomenological flow theory of higher-order strain gradient plasticity proposed by Fleck and Hutchinson(J.Mech.Phys.Solids,2001)and then improved by Fleck and Willis(J.Mech.Phys.Solids,2009)is used to investigate the surface-passivation problem and micro-scale plasticity.An extremum principle is stated for the theory involving one material length scale.To solve the initial boundary value problem,a numerical scheme based on the framework of variational constitutive updates is developed for the strain gradient plasticity theory.The main idea is that,in each incremental time step,the value of the effective plastic strain is obtained through the variation of a functional in regard to effective plastic strain,provided the displacement or deformation gradient.Numerical results for elasto-plastic foils under tension and bending,thin wires under torsion,are given by using the minimum principle and the numerical scheme.Implications for the role of dissipative gradient effect are explored for three non-proportional loading conditions:(1)stretch-passivation problem,(2)bending-passivation problem,and(3)torsion-passivation problem.The results indicate that,within the Fleck-Hutchinson-Willis theory,the dissipative length scale controls the strengthening size effect,i.e.the increase of initial yielding strength,while the surface passivation gives rise to an increase of strain hardening rate.
基金The work described in this paper was supported by General Research Grants from the Research Grants Council of the Hong Kong Special Administrative Region(Project No.CityU 11216318)City University of Hong Kong(Project No.9680213)。
文摘Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,productivity and passenger comfort in case of vehicle applications.Dissipative elastic metamaterials have caught considerable attention of scientific community due to their effective medium properties and peculiar dynamic characteristics including frequency bandgaps that can be effectively applied to attenuate and control undesirable vibration and noises.Although a substantial amount of theoretical work for effective medium characteristics and dynamic properties of acoustic/elastic metamaterials has been reported,the practical design and application of these composite structures for real-life engineering problems still remain unexplored.The present study intends to investigate a potential application of dissipative elastic metamaterials in controlling the bearing-generated vibration and noises over an ultrawide frequency range.The study is based on a simple analytical model together with rigorous finite element numerical simulations.It has been established that the dissipative characteristic of resonant system caused by larger material mismatch broadens the local resonance bandgaps beyond the bounding resonance frequency at the cost of wave transmission.In order to achieve broadband vibration and noise control,multi-resonant composite structures are embedded inside the bearing housing in five different layers.The reported results revealed the presence of broadband wave attenuation zone distributed from 3 to 52 kHz with consideration of material damping.The bearing-generated vibration and noises lying inside the wave attenuation zone will be mitigated.This feasibility study provides a new concept for the design and application of acoustic/elastic metamaterials in the bearing industry to improve machine service life and to enhance productivity and passenger comfort.
基金supported by the National Basic Research Program of China (973 Program) (2005CB221304)
文摘Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.
基金Supported by the National Natural Science Foundation of China(10371077)
文摘A fully discrete finite difference scheme for dissipative Zakharov equations is analyzed. On the basis of a series of the time-uniform priori estimates of the difference solutions, the stability of the difference scheme and the error bounds of optimal order of the difference solutions are obtained in L^2 × H^1 × H^2 over a finite time interval （0, T]. Finally, the existence of a global attractor is proved for a discrete dynamical system associated with the fully discrete finite difference scheme.
基金supported by the Natural Science Foundation of China(11001095)the Ph.D.specialized grant of the Ministry of Education of China(20100144110001)+2 种基金the Special Fund for Basic Scientific Research of Central Colleges(CCNU12C01001)supported by the Fundamental Research Funds for the Central Universities(2015IA009)the Natural Science Foundation of China(61573012)
文摘This paper is concerned with the existence and the nonlinear asymptotic stabil- ity of traveling wave solutions to the Cauchy problem for a system of dissipative evolution equations {θt=vζx＋（ζθ）x＋aθxx,ζt=-θx＋βζxx;with initial data and end states （ζθ）（x,0）=（ζ0,θ0）（x）→（ζ±,θ±）as x→∞.We obtain the existence of traveling wave solutions by phase plane analysis and show the asymptotic nonlinear stability of traveling wave solutions without restrictions on the coeffi- cients a and v by the method of energy estimates.
基金Supported by the National Natural Science Foundation of China.
文摘Excitation functions have been measured for the dissipative products of 4≤Z≤12 in ^(19)F+^(45)Sc reaction from 102 to ^(108)MeV by a step of 300keV at θl=42°.The energy coherence widths have been extracted and the dinuclear system lifetimes of the order of 10^(-21 ) s have been deduced by analysing the cross section Auctuations.
