The existence of a compact uniform attractor for a family of processes corre- sponding to the dissipative non-autonomous Klein-Gordon-SchrSdinger lattice dynamical system is proved. An upper bound of the Kolmogorov en...The existence of a compact uniform attractor for a family of processes corre- sponding to the dissipative non-autonomous Klein-Gordon-SchrSdinger lattice dynamical system is proved. An upper bound of the Kolmogorov entropy of the compact uniform attractor is obtained, and an upper semicontinuity of the compact uniform attractor is established.展开更多
With the help of three shift operators and r-matrix theory, a few discrete lattice systems are obtained which can be reduced to the well-known Toda lattice equation with a constraint whose Hamiltonian structures are g...With the help of three shift operators and r-matrix theory, a few discrete lattice systems are obtained which can be reduced to the well-known Toda lattice equation with a constraint whose Hamiltonian structures are generated by Poisson tensors of some induced Lie–Poisson bracket. The recursion operators of these lattice systems are constructed starting from Lax representations. Finally, reducing the given shift operators to get a simpler one and its expanding shift operators, we produce a lattice system with three vector fields whose recursion operator is given. Furthermore,we reduce the lattice system with three vector fields to get a lattice system whose Lax pair and conservation laws are obtained, respectively.展开更多
This paper studies the evolution of wave in the system of a pure anharmonic lattice with a double well on-site potential by numerical calculation.It finds that an initial distribution of static or moving wave can evol...This paper studies the evolution of wave in the system of a pure anharmonic lattice with a double well on-site potential by numerical calculation.It finds that an initial distribution of static or moving wave can evolve into two travelling soliton-like trains with contrary directions and a region of oscillation in this lattice system.It presents that some cases with cosine-square-shape and Gaussian-shape initial distribution of static or moving wave will produce ordered soliton-like train.Careful numerical observation shows that the centre oscillation region in this system may act as a resource of generating soliton-like train.展开更多
The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x...The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x ≤ 0.66） system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ（T） and a log T relationship in C（T） were found in the samples near xcr, indicating them to be near an AFM quantum critical point（QCP） with strong spin fluctuation. Our finding indicates that（Ce（1-x）Lax）2Ir3Ge5 may be a new platform to search for unconventional superconductivity.展开更多
In this letter, the homotopy analysis method is successfully applied to solve the Relativistic Toda lattice system. Comparisons are made between the results of the proposed method and exact solutions. Analysis results...In this letter, the homotopy analysis method is successfully applied to solve the Relativistic Toda lattice system. Comparisons are made between the results of the proposed method and exact solutions. Analysis results show that homotopy analysis method is a powerful and easy-to-use analytic tool to solve systems of differential-difference equations.展开更多
In this paper, an upper bound of fractal dimension of the compact kernel sections for the dissipative non-autonomous Klein-Gordon-Schr<span style="white-space:nowrap;">ö</span>dinger lat...In this paper, an upper bound of fractal dimension of the compact kernel sections for the dissipative non-autonomous Klein-Gordon-Schr<span style="white-space:nowrap;">ö</span>dinger lattice system is obtained, by applying a criterion for estimating fractal dimension of a family of compact subsets of a separable Hilbert space.展开更多
The clock operator U and shift operator V are higher-dimensional Pauli operators. Just recently, tighter uncertainty relations with respect to U and V were derived, and we apply them to study the electron localization...The clock operator U and shift operator V are higher-dimensional Pauli operators. Just recently, tighter uncertainty relations with respect to U and V were derived, and we apply them to study the electron localization properties in several typical one-dimensional nonuniform lattice systems. We find that uncertainties △U^2 are less than, equal to, and greater than uncertainties △V^2 for extended, critical, and localized states, respectively. The lower bound LB of the uncertainty relation is relatively large for extended states and small for localized states. Therefore, in combination with traditional quantities,for instance inverse participation ratio, these quantities can be as novel indexes to reflect Anderson localization.展开更多
The staggered mode of solitons in polyacetylene which is first discovered by Sun et al.is one of the typical gap soliton studied in lattice system.Using a one dimensional damped and parametrically driven pendulum latt...The staggered mode of solitons in polyacetylene which is first discovered by Sun et al.is one of the typical gap soliton studied in lattice system.Using a one dimensional damped and parametrically driven pendulum lattice,we have observed a stable staggered mode which can be explained successfully by a nonlinear Schrödinger equation under the multiple scale approximation.展开更多
In this paper, the extended projective approach, which was recently presented and successfully used in some continuous nonlinear physical systems, is generalized to nonlinear partial differential-difference systems （...In this paper, the extended projective approach, which was recently presented and successfully used in some continuous nonlinear physical systems, is generalized to nonlinear partial differential-difference systems （DDEs）, As a concrete example, new families of exact solutions to the （2＋1）-dimensional Toda lattice system are obtained by the extended projective approach.展开更多
We considered the longtime behavior of solutions of a coupled lattice dynamical system of Klein-Gordon-Schroedinger equation （KGS lattice system）. We first proved the existence of a global attractor for the system c...We considered the longtime behavior of solutions of a coupled lattice dynamical system of Klein-Gordon-Schroedinger equation （KGS lattice system）. We first proved the existence of a global attractor for the system considered here by introducing an equivalent norm and using ＂End Tails＂ of solutions. Then we estimated the upper bound of the Kolmogorov delta-entropy of the global attractor by applying element decomposition and the covering property of a polyhedron by balls of radii delta in the finite dimensional space. Finally, we presented an approximation to the global attractor by the global attractors of finite-dimensional ordinary differential systems.展开更多
The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characteriz...The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.展开更多
The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant ...The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant feedlines.The dynamic characteristics of valve-closing water hammer and filling water hammer are investigated by this method,and the sensitivity of filling water hammer is analyzed with a single factor sensitivity analysis with 8 factors and 9 levels and a multi-factor sensitivity analysis with L_(27)(3^(13))orthogonal experiment based on range method.It is found that the solving result of LBM with entropy limiter is basically in good agreement with finite volume method,and using the entropy limiter can eliminate numerical oscillations when solving valve-closing water hammer problems and solve the numerical"blow up"when solving filling water hammer problems.It can be seen that the dynamic characteristics of valve-closing water hammer are relatively simple,while there are many factors that affect the filling water hammer and the degree of these effects varies.The effects on the maximum water hammer pressure are relatively uniform,but those on the water hammer response time vary greatly through the skewness analysis.展开更多
Multidimensional coherent spectroscopy(MDCS)has been established in quantum chemistry as a powerful tool for studying the nonlinear response and nonequilibrium dynamics of molecular systems.More recently,the technique...Multidimensional coherent spectroscopy(MDCS)has been established in quantum chemistry as a powerful tool for studying the nonlinear response and nonequilibrium dynamics of molecular systems.More recently,the technique has also been applied to correlated electronmaterials,where the interplay of localized and itinerant states makes the interpretation of the spectra more challenging.Here we use the Keldysh contour representation of effective models and nonequilibrium dynamical mean field theory to systematically study theMDCSsignals of prototypical correlated lattice systems.By analyzing the current induced by sequences of ultrashort laser pulseswe demonstrate the usefulness ofMDCS as a diagnostic tool for excitation pathways and coherent processes in correlated solids.Wealso show that this technique allows to extract detailed information on the nature and evolution of photo-excited nonequilibrium states.展开更多
We propose schemes for realizing various forms of bright solitons,bright vortices,and breathing solitons in a non-resonant,incoherently pumped exciton-polariton condensate system by introducing a two-dimensional Moir&...We propose schemes for realizing various forms of bright solitons,bright vortices,and breathing solitons in a non-resonant,incoherently pumped exciton-polariton condensate system by introducing a two-dimensional Moirélattice external potential.The symmetric shape of the soliton,at the center of the potential field is determined by the rotation angle of the twodimensional Moirélattice external potential.Within a specific range of rotation angles,the stability of the soliton is governed by the depth of the second sub-lattice.These two parameters mutually influence and constrain the soliton’s characteristics,and under certain rotation angles and sub-lattice depths,a bright vortex can be formed.At low pumping levels and with carefully chosen peak-to-valley positions in the external potential,the rotation angle becomes the primary factor controlling the distinct forms of breathing bright solitons.Our proposal provides effective schemes for the formation and control of various types of bright solitons and bright vortices in systems employing Moirélattice external potentials.This scheme for realizing polariton Bose-Einstein condensates(BECs)within a Moirélattice external potential also holds promise for advancing research in fields such as superfluidity and superconductivity.展开更多
This study uses numerical and analytical schemes to consider the wave propagation behavior of a triply periodic minimal surface sandwich cylindrical system(TPMS-SCS)for the first time.Although these structures exhibit...This study uses numerical and analytical schemes to consider the wave propagation behavior of a triply periodic minimal surface sandwich cylindrical system(TPMS-SCS)for the first time.Although these structures exhibit outstanding physical and mechanical properties,their dynamic and acoustic features have not been reported yet.This study addresses this gap by calculating the sound transmission loss(STL)coefficient within the framework of the wave approach across various architectures,including the primitive(P),Schoen gyroid(G),and wrapped package-graph(IWP)of a TPMS lattice structure.To determine an analytical STL,a third-order approach is used to precisely capture the stress-strain distribution based on the thickness coordinate,thereby providing a simultaneous solution to the general characteristic relations along with fluid-structure coupling.Given the lack of studies for frequency and STL comparisons,the structure is modeled considering a finite element(FE)design,which is a challenging and time-consuming process because of the complex topological TPMS configurations incorporated within a sandwich cylinder.In fact,achieving convincing computational accuracy requires fine mesh discretization,which significantly increases computational costs during vibroacoustic analysis.Using the numerical results from the COMSOL software Multiphysics,the accuracy of the analytical STL spectrum is verified for different configurations,including P,G,and IWP.The effective acoustic specifications of a TPMS-SCS in the frequency domain are examined by the comparison of the STL with that of a simple cylinder of the same mass.In this context,it would also be beneficial to examine the effect of TPMS thickness,which can demonstrate the importance of the present results.The findings of this approach can be beneficial for scholars working on the numerical and analytical sound insulation characteristics of metamaterial-based cylindrical systems.展开更多
Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-ins...Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.展开更多
Blockchain offers a promising solution to the security challenges faced by the Internet of Vehicles(IoV).However,due to the dynamic connectivity of IoV,blockchain based on a single-chain structure or Directed Acyclic ...Blockchain offers a promising solution to the security challenges faced by the Internet of Vehicles(IoV).However,due to the dynamic connectivity of IoV,blockchain based on a single-chain structure or Directed Acyclic Graph(DAG)structure often suffer from performance limitations.The DAG lattice structure is a novel blockchain model in which each node maintains its own account chain,and only the node itself is allowed to update it.This feature makes the DAG lattice structure particularly suitable for addressing the challenges in dynamically connected IoV environment.In this paper,we propose a blockchain architecture based on the DAG lattice structure,specifically designed for dynamically connected IoV.In the proposed system,nodes must obtain authorization from a trusted authority before joining,forming a permissioned blockchain.Each node is assigned an individual account chain,allowing vehicles with limited storage capacity to participate in the blockchain by storing transactions only from nearby vehicles’account chains.Every transmitted message is treated as a transaction and added to the blockchain,enablingmore efficient data transmission in a dynamic network environment.Areputation-based incentivemechanism is introduced to encourage nodes to behave normally.Experimental results demonstrate that the proposed architecture achieves better performance compared with traditional single-chain and DAG-based approaches in terms of average transmission delay and storage cost.展开更多
Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenizatio...Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.展开更多
Heterostructured transition-metal compounds show great potential in the oxygen evolution reaction(OER),but the reaction mechanism induced by the surface reconstruction remains unclear.Herein,we develop a kind of Co-O-...Heterostructured transition-metal compounds show great potential in the oxygen evolution reaction(OER),but the reaction mechanism induced by the surface reconstruction remains unclear.Herein,we develop a kind of Co-O-Mo active center in Co oxyhydroxide(MoCoOOH)via in situ reconstruction,which exhibits an overpotential of 275 m V at 10 mA cm^(-2)in alkaline conditions,as well as negligible deactivation after durability operation driven by a solar cell.The operando tests reveal that Mo accelerates the reconstruction from Co-Se-Mo to Co-O-Mo in MoCoOOH,which triggers the lattice oxygen activation for enhanced intrinsic OER activity.Theoretical calculations demonstrate that the Mo atoms can optimize the d-orbital energy level of Co metal atoms,adsorption-desorption oxygenated intermediates,and the rate-determining step barrier.This work gives deep insights into the oxygen-involved mechanism in the reconstructed phase and inspires the rational design of high-activity electrocatalysts in multielectron reactions.展开更多
Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimizat...Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.展开更多
基金Project supported by the National Natural Science Foundation of China(No.10771139)the Ph.D. Program of Ministry of Education of China(No.200802700002)+4 种基金the Shanghai Leading Academic Discipline Project(No.S30405)the Innovation Program of Shanghai Municipal Education Commission(No.08ZZ70)the Foundation of Shanghai Talented Persons(No.049)the Leading Academic Discipline Project of Shanghai Normal University(No.DZL707)the Foundation of Shanghai Normal University(No.DYL200803)
文摘The existence of a compact uniform attractor for a family of processes corre- sponding to the dissipative non-autonomous Klein-Gordon-SchrSdinger lattice dynamical system is proved. An upper bound of the Kolmogorov entropy of the compact uniform attractor is obtained, and an upper semicontinuity of the compact uniform attractor is established.
基金Supported by the National Natural Science Foundation of China under Grant No.11371361the Innovation Team of Jiangsu Province Hosted by China University of Mining and Technology(2014)+4 种基金the the Key Discipline Construction by China University of Mining and Technology under Grant No.XZD201602the Shandong Provincial Natural Science Foundation,China under Grant Nos.ZR2016AM31,ZR2016AQ19,ZR2015EM042the Development of Science and Technology Plan Projects of Tai An City under Grant No.2015NS1048National Social Science Foundation of China under Grant No.13BJY026A Project of Shandong Province Higher Educational Science and Technology Program under Grant No.J14LI58
文摘With the help of three shift operators and r-matrix theory, a few discrete lattice systems are obtained which can be reduced to the well-known Toda lattice equation with a constraint whose Hamiltonian structures are generated by Poisson tensors of some induced Lie–Poisson bracket. The recursion operators of these lattice systems are constructed starting from Lax representations. Finally, reducing the given shift operators to get a simpler one and its expanding shift operators, we produce a lattice system with three vector fields whose recursion operator is given. Furthermore,we reduce the lattice system with three vector fields to get a lattice system whose Lax pair and conservation laws are obtained, respectively.
基金Project supported by the Natural Science Foundation of Hunan Province,China(Grant Nos 04JJ3078 and 04JJ6029).
文摘This paper studies the evolution of wave in the system of a pure anharmonic lattice with a double well on-site potential by numerical calculation.It finds that an initial distribution of static or moving wave can evolve into two travelling soliton-like trains with contrary directions and a region of oscillation in this lattice system.It presents that some cases with cosine-square-shape and Gaussian-shape initial distribution of static or moving wave will produce ordered soliton-like train.Careful numerical observation shows that the centre oscillation region in this system may act as a resource of generating soliton-like train.
基金supported by the National Basic Research Program of China(Grant Nos.2016FYA0300402,2015CB921004,and 2012CB821404)the National Natural Science Foundation of China(Grant Nos.11374261 and 11204059)
文摘The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x ≤ 0.66） system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ（T） and a log T relationship in C（T） were found in the samples near xcr, indicating them to be near an AFM quantum critical point（QCP） with strong spin fluctuation. Our finding indicates that（Ce（1-x）Lax）2Ir3Ge5 may be a new platform to search for unconventional superconductivity.
基金Supported by Leading Academic Discipline Program, 211 Project for Shanghai University of Finance and Economics (the 3rd phase)
文摘In this letter, the homotopy analysis method is successfully applied to solve the Relativistic Toda lattice system. Comparisons are made between the results of the proposed method and exact solutions. Analysis results show that homotopy analysis method is a powerful and easy-to-use analytic tool to solve systems of differential-difference equations.
文摘In this paper, an upper bound of fractal dimension of the compact kernel sections for the dissipative non-autonomous Klein-Gordon-Schr<span style="white-space:nowrap;">ö</span>dinger lattice system is obtained, by applying a criterion for estimating fractal dimension of a family of compact subsets of a separable Hilbert space.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61475075 and 61170321)
文摘The clock operator U and shift operator V are higher-dimensional Pauli operators. Just recently, tighter uncertainty relations with respect to U and V were derived, and we apply them to study the electron localization properties in several typical one-dimensional nonuniform lattice systems. We find that uncertainties △U^2 are less than, equal to, and greater than uncertainties △V^2 for extended, critical, and localized states, respectively. The lower bound LB of the uncertainty relation is relatively large for extended states and small for localized states. Therefore, in combination with traditional quantities,for instance inverse participation ratio, these quantities can be as novel indexes to reflect Anderson localization.
基金Supported by the National Natural Science Foundation of Chinathe Natural Science Foundation of Zhejiang Province of China
文摘The staggered mode of solitons in polyacetylene which is first discovered by Sun et al.is one of the typical gap soliton studied in lattice system.Using a one dimensional damped and parametrically driven pendulum lattice,we have observed a stable staggered mode which can be explained successfully by a nonlinear Schrödinger equation under the multiple scale approximation.
基金The project supported by the Natural Science Foundation of Zhejiang Province under Grant No. Y604106, the Foundation of New Century 151 Talent Engineering of Zhejiang Province, the Scientific Research Foundation of Key Discipline of Zhejiang Province, and the Natural Science Foundation of Zhejiang LishuiThe authors are in debt to Profs. J.F. Zhang, Z.M. Sheng, and L.Q. Chen, Drs. Z.Y. Ma and W.H. Huang for their helpful suggestions and fruitful discussions, and express their sincere thanks to Prof. S.Y. Lou for his useful references.University under Grant No. KZ05010
文摘In this paper, the extended projective approach, which was recently presented and successfully used in some continuous nonlinear physical systems, is generalized to nonlinear partial differential-difference systems （DDEs）, As a concrete example, new families of exact solutions to the （2＋1）-dimensional Toda lattice system are obtained by the extended projective approach.
基金Project supported by the National Natural Science Foundation of China (No.10471086)Specialized Research Fund for the Doctoral Program of Xiangtan University (No.06QDZ07)
文摘We considered the longtime behavior of solutions of a coupled lattice dynamical system of Klein-Gordon-Schroedinger equation （KGS lattice system）. We first proved the existence of a global attractor for the system considered here by introducing an equivalent norm and using ＂End Tails＂ of solutions. Then we estimated the upper bound of the Kolmogorov delta-entropy of the global attractor by applying element decomposition and the covering property of a polyhedron by balls of radii delta in the finite dimensional space. Finally, we presented an approximation to the global attractor by the global attractors of finite-dimensional ordinary differential systems.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12075315 and 11675261)。
文摘The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.
基金supported by the Natural Science BasicResearch Program of Shaanxi,China(No.2021JC-14)。
文摘The water hammer problem is an important issue in the dynamics of liquid propulsion system.This paper aims to use the Lattice Boltzmann Method(LBM)with entropy limiter to study the water hammer problems in propellant feedlines.The dynamic characteristics of valve-closing water hammer and filling water hammer are investigated by this method,and the sensitivity of filling water hammer is analyzed with a single factor sensitivity analysis with 8 factors and 9 levels and a multi-factor sensitivity analysis with L_(27)(3^(13))orthogonal experiment based on range method.It is found that the solving result of LBM with entropy limiter is basically in good agreement with finite volume method,and using the entropy limiter can eliminate numerical oscillations when solving valve-closing water hammer problems and solve the numerical"blow up"when solving filling water hammer problems.It can be seen that the dynamic characteristics of valve-closing water hammer are relatively simple,while there are many factors that affect the filling water hammer and the degree of these effects varies.The effects on the maximum water hammer pressure are relatively uniform,but those on the water hammer response time vary greatly through the skewness analysis.
基金supported by the Swiss National Science Foundation through the Research Unit QUAST of Deutsche Foschungsgemeinschaft(FOR5249)Grant No.200021-196966.The calculations were performed on the Beo05 cluster at the University of Fribourg.
文摘Multidimensional coherent spectroscopy(MDCS)has been established in quantum chemistry as a powerful tool for studying the nonlinear response and nonequilibrium dynamics of molecular systems.More recently,the technique has also been applied to correlated electronmaterials,where the interplay of localized and itinerant states makes the interpretation of the spectra more challenging.Here we use the Keldysh contour representation of effective models and nonequilibrium dynamical mean field theory to systematically study theMDCSsignals of prototypical correlated lattice systems.By analyzing the current induced by sequences of ultrashort laser pulseswe demonstrate the usefulness ofMDCS as a diagnostic tool for excitation pathways and coherent processes in correlated solids.Wealso show that this technique allows to extract detailed information on the nature and evolution of photo-excited nonequilibrium states.
基金support from the Natural Science Foundation of Zhejiang Province of China (Grant No. LZ22A050002)the National Natural Science Foundation of China (Grant Nos. 12074343 and 11835011)support from the postdoctoral fellowship of Zhejiang Normal University (Grant No. YS304123952)
文摘We propose schemes for realizing various forms of bright solitons,bright vortices,and breathing solitons in a non-resonant,incoherently pumped exciton-polariton condensate system by introducing a two-dimensional Moirélattice external potential.The symmetric shape of the soliton,at the center of the potential field is determined by the rotation angle of the twodimensional Moirélattice external potential.Within a specific range of rotation angles,the stability of the soliton is governed by the depth of the second sub-lattice.These two parameters mutually influence and constrain the soliton’s characteristics,and under certain rotation angles and sub-lattice depths,a bright vortex can be formed.At low pumping levels and with carefully chosen peak-to-valley positions in the external potential,the rotation angle becomes the primary factor controlling the distinct forms of breathing bright solitons.Our proposal provides effective schemes for the formation and control of various types of bright solitons and bright vortices in systems employing Moirélattice external potentials.This scheme for realizing polariton Bose-Einstein condensates(BECs)within a Moirélattice external potential also holds promise for advancing research in fields such as superfluidity and superconductivity.
文摘This study uses numerical and analytical schemes to consider the wave propagation behavior of a triply periodic minimal surface sandwich cylindrical system(TPMS-SCS)for the first time.Although these structures exhibit outstanding physical and mechanical properties,their dynamic and acoustic features have not been reported yet.This study addresses this gap by calculating the sound transmission loss(STL)coefficient within the framework of the wave approach across various architectures,including the primitive(P),Schoen gyroid(G),and wrapped package-graph(IWP)of a TPMS lattice structure.To determine an analytical STL,a third-order approach is used to precisely capture the stress-strain distribution based on the thickness coordinate,thereby providing a simultaneous solution to the general characteristic relations along with fluid-structure coupling.Given the lack of studies for frequency and STL comparisons,the structure is modeled considering a finite element(FE)design,which is a challenging and time-consuming process because of the complex topological TPMS configurations incorporated within a sandwich cylinder.In fact,achieving convincing computational accuracy requires fine mesh discretization,which significantly increases computational costs during vibroacoustic analysis.Using the numerical results from the COMSOL software Multiphysics,the accuracy of the analytical STL spectrum is verified for different configurations,including P,G,and IWP.The effective acoustic specifications of a TPMS-SCS in the frequency domain are examined by the comparison of the STL with that of a simple cylinder of the same mass.In this context,it would also be beneficial to examine the effect of TPMS thickness,which can demonstrate the importance of the present results.The findings of this approach can be beneficial for scholars working on the numerical and analytical sound insulation characteristics of metamaterial-based cylindrical systems.
基金supported by the Khalifa University of Science and Technology internal grants(Nos.2021-CIRA-109,2020-CIRA-007,and 2020-CIRA-024).
文摘Low-velocity impact tests are carried out to explore the energy absorption characteristics of bio-inspired lattices,mimicking the architecture of the marine sponge organism Euplectella aspergillum.These sea sponge-inspired lattice structures feature a square-grid 2D lattice with double diagonal bracings and are additively manufactured via digital light processing(DLP).The collapse strength and energy absorption capacity of sea sponge lattice structures are evaluated under various impact conditions and are compared to those of their constituent square-grid and double diagonal lattices.This study demonstrates that sea sponge lattices can achieve an 11-fold increase in energy absorption compared to the square-grid lattice,due to the stabilizing effect of the double diagonal bracings prompting the structure to collapse layer-bylayer under impact.By adjusting the thickness ratio in the sea sponge lattice,up to 76.7%increment in energy absorption is attained.It is also shown that sea-sponge lattices outperform well-established energy-absorbing materials of equal weight,such as hexagonal honeycombs,confirming their significant potential for impact mitigation.Additionally,this research highlights the enhancements in energy absorption achieved by adding a small amount(0.015 phr)of Multi-Walled Carbon Nanotubes(MWCNTs)to the photocurable resin,thus unlocking new possibilities for the design of innovative lightweight structures with multifunctional attributes.
基金funded in part by the Supported by Natural Science Foundation of Inner Mongolia Autonomous Region of China under Grants 2024QN06022 and 2023QN06008in part by the First-Class Discipline Research Special Project under Grant YLXKZX-NGD-015in part by the Inner Mongolia University of Technology Scientific Research Start-Up Project under Grant BS2024067.
文摘Blockchain offers a promising solution to the security challenges faced by the Internet of Vehicles(IoV).However,due to the dynamic connectivity of IoV,blockchain based on a single-chain structure or Directed Acyclic Graph(DAG)structure often suffer from performance limitations.The DAG lattice structure is a novel blockchain model in which each node maintains its own account chain,and only the node itself is allowed to update it.This feature makes the DAG lattice structure particularly suitable for addressing the challenges in dynamically connected IoV environment.In this paper,we propose a blockchain architecture based on the DAG lattice structure,specifically designed for dynamically connected IoV.In the proposed system,nodes must obtain authorization from a trusted authority before joining,forming a permissioned blockchain.Each node is assigned an individual account chain,allowing vehicles with limited storage capacity to participate in the blockchain by storing transactions only from nearby vehicles’account chains.Every transmitted message is treated as a transaction and added to the blockchain,enablingmore efficient data transmission in a dynamic network environment.Areputation-based incentivemechanism is introduced to encourage nodes to behave normally.Experimental results demonstrate that the proposed architecture achieves better performance compared with traditional single-chain and DAG-based approaches in terms of average transmission delay and storage cost.
基金Project supported by the National Natural Science Foundation of China(No.12472077)the supports from Shanghai Gaofeng Project for University Academic Program Development,Fundamental Research Funds for the Central Universities(No.22120240353).
文摘Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.
基金financially supported in part by the National Key R&D Program of China(2020YFA0405800)the National Natural Science Foundation of China(Grant No.U1932201)the Natural Science Foundation of the Jiangsu Higher Education Institutions(23KJA430001)。
文摘Heterostructured transition-metal compounds show great potential in the oxygen evolution reaction(OER),but the reaction mechanism induced by the surface reconstruction remains unclear.Herein,we develop a kind of Co-O-Mo active center in Co oxyhydroxide(MoCoOOH)via in situ reconstruction,which exhibits an overpotential of 275 m V at 10 mA cm^(-2)in alkaline conditions,as well as negligible deactivation after durability operation driven by a solar cell.The operando tests reveal that Mo accelerates the reconstruction from Co-Se-Mo to Co-O-Mo in MoCoOOH,which triggers the lattice oxygen activation for enhanced intrinsic OER activity.Theoretical calculations demonstrate that the Mo atoms can optimize the d-orbital energy level of Co metal atoms,adsorption-desorption oxygenated intermediates,and the rate-determining step barrier.This work gives deep insights into the oxygen-involved mechanism in the reconstructed phase and inspires the rational design of high-activity electrocatalysts in multielectron reactions.
基金supported by the National Natural Science Foundation of China(Grant Nos.12432005 and 12472116)the Fundamental Research Funds for the Central Universities(DUTZD25240).
文摘Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.
