This paper addresses the verification of strong currentstate opacity with respect to real-time observations generated from a discrete-event system that is modeled with time labeled Petri nets. The standard current-sta...This paper addresses the verification of strong currentstate opacity with respect to real-time observations generated from a discrete-event system that is modeled with time labeled Petri nets. The standard current-state opacity cannot completely characterize higher-level security. To ensure the higher-level security requirements of a time-dependent system, we propose a strong version of opacity known as strong current-state opacity. For any path(state-event sequence with time information)π derived from a real-time observation that ends at a secret state, the strong current-state opacity of the real-time observation signifies that there is a non-secret path with the same real-time observation as π. We propose general and non-secret state class graphs, which characterize the general and non-secret states of time-dependent systems, respectively. To capture the observable behavior of non-secret states, a non-secret observer is proposed.Finally, we develop a structure called a real-time concurrent verifier to verify the strong current-state opacity of time labeled Petri nets. This approach is efficient since the real-time concurrent verifier can be constructed by solving a certain number of linear programming problems.展开更多
An investigation and outline of MetaControl and DeControl in Metaverses for control intelligence and knowledge automation are presented.Prescriptive control with prescriptive knowledge and parallel philosophy is propo...An investigation and outline of MetaControl and DeControl in Metaverses for control intelligence and knowledge automation are presented.Prescriptive control with prescriptive knowledge and parallel philosophy is proposed as the starting point for the new control philosophy and technology,especially for computational control of metasystems in cyberphysical-social systems.We argue that circular causality,the generalized feedback mechanism for complex and purposive systems,should be adapted as the fundamental principle for control and management of metasystems with metacomplexity in metaverses.Particularly,an interdisciplinary approach is suggested for MetaControl and DeControl as a new form of intelligent control based on five control metaverses:MetaVerses,MultiVerses,InterVerses,TransVerse,and DeepVerses.展开更多
A cyber physical system(CPS)is a complex system that integrates sensing,computation,control and networking into physical processes and objects over Internet.It plays a key role in modern industry since it connects phy...A cyber physical system(CPS)is a complex system that integrates sensing,computation,control and networking into physical processes and objects over Internet.It plays a key role in modern industry since it connects physical and cyber worlds.In order to meet ever-changing industrial requirements,its structures and functions are constantly improved.Meanwhile,new security issues have arisen.A ubiquitous problem is the fact that cyber attacks can cause significant damage to industrial systems,and thus has gained increasing attention from researchers and practitioners.This paper presents a survey of state-of-the-art results of cyber attacks on cyber physical systems.First,as typical system models are employed to study these systems,time-driven and event-driven systems are reviewed.Then,recent advances on three types of attacks,i.e.,those on availability,integrity,and confidentiality are discussed.In particular,the detailed studies on availability and integrity attacks are introduced from the perspective of attackers and defenders.Namely,both attack and defense strategies are discussed based on different system models.Some challenges and open issues are indicated to guide future research and inspire the further exploration of this increasingly important area.展开更多
The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the pe...The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0展开更多
This paper investigates the consensus problem for linear multi-agent systems with the heterogeneous disturbances generated by the Brown motion.Its main contribution is that a control scheme is designed to achieve the ...This paper investigates the consensus problem for linear multi-agent systems with the heterogeneous disturbances generated by the Brown motion.Its main contribution is that a control scheme is designed to achieve the dynamic consensus for the multi-agent systems in directed topology interfered by stochastic noise.In traditional ways,the coupling weights depending on the communication structure are static.A new distributed controller is designed based on Riccati inequalities,while updating the coupling weights associated with the gain matrix by state errors between adjacent agents.By introducing time-varying coupling weights into this novel control law,the state errors between leader and followers asymptotically converge to the minimum value utilizing the local interaction.Through the Lyapunov directed method and It?formula,the stability of the closed-loop system with the proposed control law is analyzed.Two simulation results conducted by the new and traditional schemes are presented to demonstrate the effectiveness and advantage of the developed control method.展开更多
The opaque property plays an important role in the operation of a security-critical system,implying that pre-defined secret information of the system is not able to be inferred through partially observing its behavior...The opaque property plays an important role in the operation of a security-critical system,implying that pre-defined secret information of the system is not able to be inferred through partially observing its behavior.This paper addresses the verification of current-state,initial-state,infinite-step,and K-step opacity of networked discrete event systems modeled by labeled Petri nets,where communication losses and delays are considered.Based on the symbolic technique for the representation of states in Petri nets,an observer and an estimator are designed for the verification of current-state and initial-state opacity,respectively.Then,we propose a structure called an I-observer that is combined with secret states to verify whether a networked discrete event system is infinite-step opaque or K-step opaque.Due to the utilization of symbolic approaches for the state-based opacity verification,the computation of the reachability graphs of labeled Petri nets is avoided,which dramatically reduces the computational overheads stemming from networked discrete event systems.展开更多
Stochastic switched epidemic systems with a discrete or distributed time delay are constructed and investigated. By the Lyapunov method and lto＇s differential rule, the existence and uniqueness of global positive sol...Stochastic switched epidemic systems with a discrete or distributed time delay are constructed and investigated. By the Lyapunov method and lto＇s differential rule, the existence and uniqueness of global positive solution of each system is proved. And stability conditions of the disease-free equilibrium of the systems are obtained. Numerical simulations are presented to illustrate the results.展开更多
A special type of asymptotic (exponential) stability, namely componentwise asymptotic (exponential) stability for the continuous-time interval system is investigated. A set-valued map that represents the constraint of...A special type of asymptotic (exponential) stability, namely componentwise asymptotic (exponential) stability for the continuous-time interval system is investigated. A set-valued map that represents the constraint of the state of the system is defined. And, by applying the viability theory of differential equation, sufficient and necessary conditions for the componentwise asymptotical (exponential) stability of this kind of systems are given.展开更多
We study the influence of conformity on the evolution of cooperative behavior in games under the learning method of sampling on networks.A strategy update rule based on sampling is introduced into the stag hunt game,w...We study the influence of conformity on the evolution of cooperative behavior in games under the learning method of sampling on networks.A strategy update rule based on sampling is introduced into the stag hunt game,where agents draw samples from their neighbors and then update their strategies based on conformity or inference according to the situation in the sample.Based on these assumptions,we present the state transition equations in the dynamic evolution of population cooperation,conduct simulation analysis on lattice networks and scale-free networks,and discuss how this mechanism affects the evolution of cooperation and how cooperation evolves under different levels of conformity in the network.Our simulation results show that blindly imitating the strategies of neighbors does not necessarily lead to rapid consensus in the population.Instead,rational inference through samples can better promote the evolution of the same strategy among all agents in the population.Moreover,the simulation results also show that a smaller sample size cannot reflect the true situation of the neighbors,which has a large randomness,and the size of the benefits obtained in cooperation determines the direction of the entire population towards cooperation or defection.This work incorporates the conforming behavior of agents into the game,uses the method of sampling for strategy updates and enriches the theory of evolutionary games with a more realistic significance.展开更多
For 1<p<∞,Coifman-Rochberg-Weiss established L^(p) boundedness of commutators of smooth kernels.Later,many works tried to weaken the smooth condition.In this paper,we extend these mentioned results to the case ...For 1<p<∞,Coifman-Rochberg-Weiss established L^(p) boundedness of commutators of smooth kernels.Later,many works tried to weaken the smooth condition.In this paper,we extend these mentioned results to the case of non-homogeneous but with strong H¨ormander condition.Our main skills lie in wavelet decomposition,wavelet commutators,Hardy-Littlewood maximal operator and Fefferman-Stein's vector-valued maximum function Theorem.展开更多
As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environ...As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environments where traditional polymer rubber fails.In this paper,a multi-scale finite element model for EDMMR is constructed using virtual manufacturing technology(VMT).Thermo-mechanical coupling analysis reveals a distinct inward expansion and dissipation phenomenon in EDMMR under high-temperature conditions,distinguishing it from porous materials.This phenomenon has the potential to impact the overall dimensions of EDMMR through transmission and accumulation processes.The experimental results demonstrate a random distribution of internal micro springs in EDMMR,considering the contact composition of spring microelements and the pore structure.By incorporating material elasticity,a predictive method for the thermal expansion coefficient of EDMMR based on the Schapery model is proposed.Additionally,standardized processes are employed to manufacture multiple sets of cylindrical EDMMR samples with similar dimensions but varying porosities.Thermal expansion tests are conducted on these samples,and the accuracy of the predicted thermal expansion coefficient is quantitatively validated through residual analysis.This research indicates that EDMMR maintains good structural stability in high-temperature environments.The thermal expansion rate of the material exhibits an opposite trend to the variation of elastic modulus with temperature,as the porosity rate changes.展开更多
With the development of cyber-physical systems,system security faces more risks from cyber-attacks.In this work,we study the problem that an external attacker implements covert sensor and actuator attacks with resourc...With the development of cyber-physical systems,system security faces more risks from cyber-attacks.In this work,we study the problem that an external attacker implements covert sensor and actuator attacks with resource constraints(the total resource consumption of the attacks is not greater than a given initial resource of the attacker)to mislead a discrete event system under supervisory control to reach unsafe states.We consider that the attacker can implement two types of attacks:One by modifying the sensor readings observed by a supervisor and the other by enabling the actuator commands disabled by the supervisor.Each attack has its corresponding resource consumption and remains covert.To solve this problem,we first introduce a notion of combined-attackability to determine whether a closedloop system may reach an unsafe state after receiving attacks with resource constraints.We develop an algorithm to construct a corrupted supervisor under attacks,provide a verification method for combined-attackability in polynomial time based on a plant,a corrupted supervisor,and an attacker's initial resource,and propose a corresponding attack synthesis algorithm.The effectiveness of the proposed method is illustrated by an example.展开更多
This paper highlights the utilization of parallel control and adaptive dynamic programming(ADP) for event-triggered robust parallel optimal consensus control(ETRPOC) of uncertain nonlinear continuous-time multiagent s...This paper highlights the utilization of parallel control and adaptive dynamic programming(ADP) for event-triggered robust parallel optimal consensus control(ETRPOC) of uncertain nonlinear continuous-time multiagent systems(MASs).First, the parallel control system, which consists of a virtual control variable and a specific auxiliary variable obtained from the coupled Hamiltonian, allows general systems to be transformed into affine systems. Of interest is the fact that the parallel control technique's introduction provides an unprecedented perspective on eliminating the negative effects of disturbance. Then, an eventtriggered mechanism is adopted to save communication resources while ensuring the system's stability. The coupled HamiltonJacobi(HJ) equation's solution is approximated using a critic neural network(NN), whose weights are updated in response to events. Furthermore, theoretical analysis reveals that the weight estimation error is uniformly ultimately bounded(UUB). Finally,numerical simulations demonstrate the effectiveness of the developed ETRPOC method.展开更多
To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrro...To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrrolidone(PVP)on the AgO cathode material were investigated.The samples were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),cyclic voltammetry(CV),electrochemical impedance spectrum(EIS),and galvanostatic discharge.In contrast to the pure AgO and AgO−PTFE electrodes,the results demonstrated that the PVP effectively bound the electrode materials together.The prepared AgO−PVP as the cathode material of AgO−Al batteries could improve the battery capacity,exhibiting a high specific capacity(389.95 mA·h/g at 500 mA/cm^(2)),a high operating voltage(1.75 V at 500 mA/cm^(2)),a maximum energy density(665.65 W·h/kg),and a maximum power density(5236 W/kg).Furthermore,the electrochemical mechanism of the AgO−PVP cathode material was examined,revealing that the electrode exhibited rapid ion diffusion and effective interfacial ion/electron transport.展开更多
Abstract Data-driven tools, such as principal component analysis （PCA） and independent component analysis （ICA） have been applied to different benchmarks as process monitoring methods. The difference between the t...Abstract Data-driven tools, such as principal component analysis （PCA） and independent component analysis （ICA） have been applied to different benchmarks as process monitoring methods. The difference between the two methods is that the components of PCA are still dependent while ICA has no orthogonality constraint and its latentvariables are independent. Process monitoring with PCA often supposes that process data or principal components is Gaussian distribution. However, this kind of constraint cannot be satisfied by several practical processes. To ex-tend the use of PCA, a nonparametric method is added to PCA to overcome the difficulty, and kernel density estimation （KDE） is rather a good choice. Though ICA is based on non-Gaussian distribution intormation, .KDE can help in the close monitoring of the data. Methods, such as PCA, ICA, PCA.with .KDE（KPCA）, and ICA with KDE,（KICA）, are demonstrated and. compared by applying them to a practical industnal Spheripol craft polypropylene catalyzer reactor instead of a laboratory emulator.展开更多
The fracture behavior of polymer-bonded explosive(PBX) seriously affects the safety and reliability of weapon system.The effects of interface debonding and initial meso-damage on the fracture behavior of PBX under qua...The fracture behavior of polymer-bonded explosive(PBX) seriously affects the safety and reliability of weapon system.The effects of interface debonding and initial meso-damage on the fracture behavior of PBX under quasi-static tension are studied using numerical method.A twodimensional representative volume element(RVE) is established based on Voronoi model in which the component contents could be regulated and the particles are randomly distributed.A nonlinear damage model of polymer matrix relative to matrix depth between particles is constructed.The results show that the simulated strain-stress relation is coincident with experiment data.It is found that interface debonding leads to the nucleation and propagation of meso-cracks,and a main crack approximately perpendicular to the loading direction is generated finally.The interface debonding tends to occur in the interface perpendicular to the loading direction.There seems to be a phenomenon that strain softening and hardening alternatively appear around peak stress of stress and strain curve.It is shown that the initial damages of intragranular and interfacial cracks both decrease the modulus and failure stress,and the main crack tends to propagate toward the initial meso-cracks.展开更多
In this paper,a new parallel controller is developed for continuous-time linear systems.The main contribution of the method is to establish a new parallel control law,where both state and control are considered as the...In this paper,a new parallel controller is developed for continuous-time linear systems.The main contribution of the method is to establish a new parallel control law,where both state and control are considered as the input.The structure of the parallel control is provided,and the relationship between the parallel control and traditional feedback controls is presented.Considering the situations that the systems are controllable and incompletely controllable,the properties of the parallel control law are analyzed.The parallel controller design algorithms are given under the conditions that the systems are controllable and incompletely controllable.Finally,numerical simulations are carried out to demonstrate the effectiveness and applicability of the present method.Index Terms-Continuous-time linear systems,digital twin,parallel controller,parallel intelligence,parallel systems.展开更多
According to the dimensionless formulae of DOP(depth of penetration) of a rigid projectile into different targets,the resistive force which a target exerts on the projectile during the penetration of rigid projectile ...According to the dimensionless formulae of DOP(depth of penetration) of a rigid projectile into different targets,the resistive force which a target exerts on the projectile during the penetration of rigid projectile is theoretically analyzed.In particular,the threshold V_C of impact velocity applicable for the assumption of constant resistive force is formulated through impulse analysis.The various values of V_C corresponding to different pairs of projectile-target are calculated,and the consistency of the relative test data and numerical results is observed.展开更多
In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the ...In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.展开更多
基金supported by the Special Fund for Scientific and Technological Innovation Strategy of Guangdong Province(2022A0505030025)the Science and Technology Fund,FDCT,Macao SAR(0064/2021/A2)
文摘This paper addresses the verification of strong currentstate opacity with respect to real-time observations generated from a discrete-event system that is modeled with time labeled Petri nets. The standard current-state opacity cannot completely characterize higher-level security. To ensure the higher-level security requirements of a time-dependent system, we propose a strong version of opacity known as strong current-state opacity. For any path(state-event sequence with time information)π derived from a real-time observation that ends at a secret state, the strong current-state opacity of the real-time observation signifies that there is a non-secret path with the same real-time observation as π. We propose general and non-secret state class graphs, which characterize the general and non-secret states of time-dependent systems, respectively. To capture the observable behavior of non-secret states, a non-secret observer is proposed.Finally, we develop a structure called a real-time concurrent verifier to verify the strong current-state opacity of time labeled Petri nets. This approach is efficient since the real-time concurrent verifier can be constructed by solving a certain number of linear programming problems.
文摘An investigation and outline of MetaControl and DeControl in Metaverses for control intelligence and knowledge automation are presented.Prescriptive control with prescriptive knowledge and parallel philosophy is proposed as the starting point for the new control philosophy and technology,especially for computational control of metasystems in cyberphysical-social systems.We argue that circular causality,the generalized feedback mechanism for complex and purposive systems,should be adapted as the fundamental principle for control and management of metasystems with metacomplexity in metaverses.Particularly,an interdisciplinary approach is suggested for MetaControl and DeControl as a new form of intelligent control based on five control metaverses:MetaVerses,MultiVerses,InterVerses,TransVerse,and DeepVerses.
基金supported by Institutional Fund Projects(IFPNC-001-135-2020)technical and financial support from the Ministry of Education and King Abdulaziz University,DSR,Jeddah,Saudi Arabia。
文摘A cyber physical system(CPS)is a complex system that integrates sensing,computation,control and networking into physical processes and objects over Internet.It plays a key role in modern industry since it connects physical and cyber worlds.In order to meet ever-changing industrial requirements,its structures and functions are constantly improved.Meanwhile,new security issues have arisen.A ubiquitous problem is the fact that cyber attacks can cause significant damage to industrial systems,and thus has gained increasing attention from researchers and practitioners.This paper presents a survey of state-of-the-art results of cyber attacks on cyber physical systems.First,as typical system models are employed to study these systems,time-driven and event-driven systems are reviewed.Then,recent advances on three types of attacks,i.e.,those on availability,integrity,and confidentiality are discussed.In particular,the detailed studies on availability and integrity attacks are introduced from the perspective of attackers and defenders.Namely,both attack and defense strategies are discussed based on different system models.Some challenges and open issues are indicated to guide future research and inspire the further exploration of this increasingly important area.
基金supported by the National Outstanding Young Scientists Foundation of China(11225213)the Funds for Creative Research Groups of China(51321064)the National Natural Science Foundation of China(11172282 and 51378015)
文摘The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0
基金supported in part by the National Natural Science Foundation of China(61722312,61533017,62073321)the National Key Research and Development Program of China(2018YFB1702300)。
文摘This paper investigates the consensus problem for linear multi-agent systems with the heterogeneous disturbances generated by the Brown motion.Its main contribution is that a control scheme is designed to achieve the dynamic consensus for the multi-agent systems in directed topology interfered by stochastic noise.In traditional ways,the coupling weights depending on the communication structure are static.A new distributed controller is designed based on Riccati inequalities,while updating the coupling weights associated with the gain matrix by state errors between adjacent agents.By introducing time-varying coupling weights into this novel control law,the state errors between leader and followers asymptotically converge to the minimum value utilizing the local interaction.Through the Lyapunov directed method and It?formula,the stability of the closed-loop system with the proposed control law is analyzed.Two simulation results conducted by the new and traditional schemes are presented to demonstrate the effectiveness and advantage of the developed control method.
基金supported by the National R&D Program of China(2018YFB 1700104)the Science and Technology Development FundMacao Special Administrative Region(MSAR)(0029/2023/RIA1)。
文摘The opaque property plays an important role in the operation of a security-critical system,implying that pre-defined secret information of the system is not able to be inferred through partially observing its behavior.This paper addresses the verification of current-state,initial-state,infinite-step,and K-step opacity of networked discrete event systems modeled by labeled Petri nets,where communication losses and delays are considered.Based on the symbolic technique for the representation of states in Petri nets,an observer and an estimator are designed for the verification of current-state and initial-state opacity,respectively.Then,we propose a structure called an I-observer that is combined with secret states to verify whether a networked discrete event system is infinite-step opaque or K-step opaque.Due to the utilization of symbolic approaches for the state-based opacity verification,the computation of the reachability graphs of labeled Petri nets is avoided,which dramatically reduces the computational overheads stemming from networked discrete event systems.
基金supported by the National Natural Science Foundation of China(60874114)
文摘Stochastic switched epidemic systems with a discrete or distributed time delay are constructed and investigated. By the Lyapunov method and lto＇s differential rule, the existence and uniqueness of global positive solution of each system is proved. And stability conditions of the disease-free equilibrium of the systems are obtained. Numerical simulations are presented to illustrate the results.
基金This project was supported by the National Natural Science Foundation of China (7017004).
文摘A special type of asymptotic (exponential) stability, namely componentwise asymptotic (exponential) stability for the continuous-time interval system is investigated. A set-valued map that represents the constraint of the state of the system is defined. And, by applying the viability theory of differential equation, sufficient and necessary conditions for the componentwise asymptotical (exponential) stability of this kind of systems are given.
基金Project supported by the National Natural Science Foundation of China(Grant No.72031009)the National Social Science Foundation of China(Grant No.20&ZD058)。
文摘We study the influence of conformity on the evolution of cooperative behavior in games under the learning method of sampling on networks.A strategy update rule based on sampling is introduced into the stag hunt game,where agents draw samples from their neighbors and then update their strategies based on conformity or inference according to the situation in the sample.Based on these assumptions,we present the state transition equations in the dynamic evolution of population cooperation,conduct simulation analysis on lattice networks and scale-free networks,and discuss how this mechanism affects the evolution of cooperation and how cooperation evolves under different levels of conformity in the network.Our simulation results show that blindly imitating the strategies of neighbors does not necessarily lead to rapid consensus in the population.Instead,rational inference through samples can better promote the evolution of the same strategy among all agents in the population.Moreover,the simulation results also show that a smaller sample size cannot reflect the true situation of the neighbors,which has a large randomness,and the size of the benefits obtained in cooperation determines the direction of the entire population towards cooperation or defection.This work incorporates the conforming behavior of agents into the game,uses the method of sampling for strategy updates and enriches the theory of evolutionary games with a more realistic significance.
基金partially supported by the research grant of Macao University of Science and Technology(FRG-22-075-MCMS)the Macao Government Research Funding(FDCT0128/2022/A)+2 种基金the Science and Technology Development Fund of Macao SAR(005/2022/ALC)the Science and Technology Development Fund of Macao SAR(0045/2021/A)Macao University of Science and Technology(FRG-20-021-MISE)。
文摘For 1<p<∞,Coifman-Rochberg-Weiss established L^(p) boundedness of commutators of smooth kernels.Later,many works tried to weaken the smooth condition.In this paper,we extend these mentioned results to the case of non-homogeneous but with strong H¨ormander condition.Our main skills lie in wavelet decomposition,wavelet commutators,Hardy-Littlewood maximal operator and Fefferman-Stein's vector-valued maximum function Theorem.
基金Supported by National Natural Science Foundation of China(Grant Nos.U2330202,52175162,51805086,51975123)Fujian Provincial Technological Innovation Key Research and Industrialization Projects(Grant Nos.2023XQ005,2024XQ010)Project of Guangdong Provincial Science and Technology Bureau of Jiangmen City(Grant No.2023780200030009506)。
文摘As a novel lightweight metallic material with excellent heat and corrosion resistance,elastic disordered microporous metal rubber(EDMMR)functions as an effective damping and support element in high-temperature environments where traditional polymer rubber fails.In this paper,a multi-scale finite element model for EDMMR is constructed using virtual manufacturing technology(VMT).Thermo-mechanical coupling analysis reveals a distinct inward expansion and dissipation phenomenon in EDMMR under high-temperature conditions,distinguishing it from porous materials.This phenomenon has the potential to impact the overall dimensions of EDMMR through transmission and accumulation processes.The experimental results demonstrate a random distribution of internal micro springs in EDMMR,considering the contact composition of spring microelements and the pore structure.By incorporating material elasticity,a predictive method for the thermal expansion coefficient of EDMMR based on the Schapery model is proposed.Additionally,standardized processes are employed to manufacture multiple sets of cylindrical EDMMR samples with similar dimensions but varying porosities.Thermal expansion tests are conducted on these samples,and the accuracy of the predicted thermal expansion coefficient is quantitatively validated through residual analysis.This research indicates that EDMMR maintains good structural stability in high-temperature environments.The thermal expansion rate of the material exhibits an opposite trend to the variation of elastic modulus with temperature,as the porosity rate changes.
基金partially supported by the Science Technology Development Fund,Macao Special Administrative Region(0029/2023/RIA1)the National Research Foundation Singapore under its AI Singapore Programme(AISG2-GC-2023-007)
文摘With the development of cyber-physical systems,system security faces more risks from cyber-attacks.In this work,we study the problem that an external attacker implements covert sensor and actuator attacks with resource constraints(the total resource consumption of the attacks is not greater than a given initial resource of the attacker)to mislead a discrete event system under supervisory control to reach unsafe states.We consider that the attacker can implement two types of attacks:One by modifying the sensor readings observed by a supervisor and the other by enabling the actuator commands disabled by the supervisor.Each attack has its corresponding resource consumption and remains covert.To solve this problem,we first introduce a notion of combined-attackability to determine whether a closedloop system may reach an unsafe state after receiving attacks with resource constraints.We develop an algorithm to construct a corrupted supervisor under attacks,provide a verification method for combined-attackability in polynomial time based on a plant,a corrupted supervisor,and an attacker's initial resource,and propose a corresponding attack synthesis algorithm.The effectiveness of the proposed method is illustrated by an example.
基金supported in part by the National Key Research and Development Program of China(2021YFE0206100)the National Natural Science Foundation of China(62425310,62073321)+2 种基金the National Defense Basic Scientific Research Program(JCKY2019203C029,JCKY2020130C025)the Science and Technology Development FundMacao SAR(FDCT-22-009-MISE,0060/2021/A2,0015/2020/AMJ)
文摘This paper highlights the utilization of parallel control and adaptive dynamic programming(ADP) for event-triggered robust parallel optimal consensus control(ETRPOC) of uncertain nonlinear continuous-time multiagent systems(MASs).First, the parallel control system, which consists of a virtual control variable and a specific auxiliary variable obtained from the coupled Hamiltonian, allows general systems to be transformed into affine systems. Of interest is the fact that the parallel control technique's introduction provides an unprecedented perspective on eliminating the negative effects of disturbance. Then, an eventtriggered mechanism is adopted to save communication resources while ensuring the system's stability. The coupled HamiltonJacobi(HJ) equation's solution is approximated using a critic neural network(NN), whose weights are updated in response to events. Furthermore, theoretical analysis reveals that the weight estimation error is uniformly ultimately bounded(UUB). Finally,numerical simulations demonstrate the effectiveness of the developed ETRPOC method.
基金supported by the Fundamental Research Funds for the Central Universities of Central South University,China(No.2022XQLH046)the Technical Area Fund of Foundation Strengthening,China(No.2022-JCJQ-ZD-174-00-20)National Defense Basic Scientific Research Projects,China,and Central South University−Zijin Mining Technical Cooperation Development Project,China.
文摘To improve the slow kinetics and poor mechanical strength of aqueous silver peroxide−aluminum(AgO−Al)battery cathode materials,the effects of different binders including polytetrafluoroethylene(PTFE)and polyvinylpyrrolidone(PVP)on the AgO cathode material were investigated.The samples were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),cyclic voltammetry(CV),electrochemical impedance spectrum(EIS),and galvanostatic discharge.In contrast to the pure AgO and AgO−PTFE electrodes,the results demonstrated that the PVP effectively bound the electrode materials together.The prepared AgO−PVP as the cathode material of AgO−Al batteries could improve the battery capacity,exhibiting a high specific capacity(389.95 mA·h/g at 500 mA/cm^(2)),a high operating voltage(1.75 V at 500 mA/cm^(2)),a maximum energy density(665.65 W·h/kg),and a maximum power density(5236 W/kg).Furthermore,the electrochemical mechanism of the AgO−PVP cathode material was examined,revealing that the electrode exhibited rapid ion diffusion and effective interfacial ion/electron transport.
基金Supported by the National Natural Science Foundation of China （No.60574047） and the Doctorate Foundation of the State Education Ministry of China （No.20050335018）.
文摘Abstract Data-driven tools, such as principal component analysis （PCA） and independent component analysis （ICA） have been applied to different benchmarks as process monitoring methods. The difference between the two methods is that the components of PCA are still dependent while ICA has no orthogonality constraint and its latentvariables are independent. Process monitoring with PCA often supposes that process data or principal components is Gaussian distribution. However, this kind of constraint cannot be satisfied by several practical processes. To ex-tend the use of PCA, a nonparametric method is added to PCA to overcome the difficulty, and kernel density estimation （KDE） is rather a good choice. Though ICA is based on non-Gaussian distribution intormation, .KDE can help in the close monitoring of the data. Methods, such as PCA, ICA, PCA.with .KDE（KPCA）, and ICA with KDE,（KICA）, are demonstrated and. compared by applying them to a practical industnal Spheripol craft polypropylene catalyzer reactor instead of a laboratory emulator.
文摘The fracture behavior of polymer-bonded explosive(PBX) seriously affects the safety and reliability of weapon system.The effects of interface debonding and initial meso-damage on the fracture behavior of PBX under quasi-static tension are studied using numerical method.A twodimensional representative volume element(RVE) is established based on Voronoi model in which the component contents could be regulated and the particles are randomly distributed.A nonlinear damage model of polymer matrix relative to matrix depth between particles is constructed.The results show that the simulated strain-stress relation is coincident with experiment data.It is found that interface debonding leads to the nucleation and propagation of meso-cracks,and a main crack approximately perpendicular to the loading direction is generated finally.The interface debonding tends to occur in the interface perpendicular to the loading direction.There seems to be a phenomenon that strain softening and hardening alternatively appear around peak stress of stress and strain curve.It is shown that the initial damages of intragranular and interfacial cracks both decrease the modulus and failure stress,and the main crack tends to propagate toward the initial meso-cracks.
基金supported in part by the National Key Research and Development Program of China(2018AAA0101502,2018YFB1702300)the National Natural Science Foundation of China(61722312,61533019,U1811463,61533017)。
文摘In this paper,a new parallel controller is developed for continuous-time linear systems.The main contribution of the method is to establish a new parallel control law,where both state and control are considered as the input.The structure of the parallel control is provided,and the relationship between the parallel control and traditional feedback controls is presented.Considering the situations that the systems are controllable and incompletely controllable,the properties of the parallel control law are analyzed.The parallel controller design algorithms are given under the conditions that the systems are controllable and incompletely controllable.Finally,numerical simulations are carried out to demonstrate the effectiveness and applicability of the present method.Index Terms-Continuous-time linear systems,digital twin,parallel controller,parallel intelligence,parallel systems.
基金supported by the National Outstanding Young Scientist Foundation of China(11225213)Major Program of National Natural Science Foundation of China(Grant No.11390362)
文摘According to the dimensionless formulae of DOP(depth of penetration) of a rigid projectile into different targets,the resistive force which a target exerts on the projectile during the penetration of rigid projectile is theoretically analyzed.In particular,the threshold V_C of impact velocity applicable for the assumption of constant resistive force is formulated through impulse analysis.The various values of V_C corresponding to different pairs of projectile-target are calculated,and the consistency of the relative test data and numerical results is observed.
基金supported by the Science and Technology Development Fund (2015B0201025)the key subject "Computational Solid Mechanics" of China Academy of Engineering Physics+1 种基金the National Outstanding Young Scientists Foundation of China (11225213)the National Natural Science Foundation of China (11521062,11602258)
文摘In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.
