The research on spatial epidemic models is a topic of considerable recent interest. In another hand, the advances in computer technology have stimulated the development of stochastic models. Metapopulation models are ...The research on spatial epidemic models is a topic of considerable recent interest. In another hand, the advances in computer technology have stimulated the development of stochastic models. Metapopulation models are spatial designs that involve movements of individuals between distinct subpopulations. The purpose of the present work has been to develop stochastic models in order to study the transmission dynamics and control of infectious diseases in metapopulations. The authors studied Susceptible-Infected-Susceptible （SIS） and Susceptible-lnfected-Recovered （SIR） epidemic schemes, using the Gillespie algorithm, Computational numerical simulations were carried in order to explore the models. The results obtained show how the dynamics of transmission and the application of control measures within each subpopulation may affect all subpopulations of the system. They also show how the distribution of control measures among subpopulations affects the efficacy of these strategies. The dynamics of the stochastic models developed in the current study follow the trends observed in the classic deterministic designs. Also, the present models exhibit fluctuating behavior. This work highlights the importance of the spatial distribution of the population in spread and control of infectious diseases. In addition, it shows how chance could play an important role in these scenarios.展开更多
Animal flight and swimming have long been of great interest to people.Besides curiosity about how their sophisticated aero-and hydrodynamic feats are performed,researches are very interested in the mechanics of animal...Animal flight and swimming have long been of great interest to people.Besides curiosity about how their sophisticated aero-and hydrodynamic feats are performed,researches are very interested in the mechanics of animal flight and swimming for the following two reasons.One is that biologists need to understand the effects of aero-and hydrodynamic force production and energy expenditure on the physiology,behavior,evolution and other aspects of the animals.The展开更多
Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the mode...Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the modeling of dynamics environment and the orbital dynamics mechanism. This paper introduced state-ofthe-art researches, major challenges, and future trends in this field. Three topics are mainly discussed： the gravitational field modeling of irregular-shaped small celestial bodies, natural orbital dynamics and control, and controlled orbital dynamics. Finally, constructive suggestions are made for China’s future space exploration missions.展开更多
The dynamics and control of a tetrahedral spacecraft formation flying in the Sun-Earth L2 region is initiatively studied,based on the circular restricted three-body problem(CR3BP).Driven by the science goal of identif...The dynamics and control of a tetrahedral spacecraft formation flying in the Sun-Earth L2 region is initiatively studied,based on the circular restricted three-body problem(CR3BP).Driven by the science goal of identifying extra-solar terrestrial planets and the requirement of imaging optics,a conceptional four-spacecraft triangular pyramid configuration has been proposed for the Multiple-spacecraft Exoplanet Aperture sYnthetic INterferometer(MEAYIN)project,China’s first mid-infrared interferometric imaging mission.Although it looked promising from an optical perspective,the configuration has not been verified dynamically.The formation is required to be virtually“rigid”,because its mutual distances and inertial pointing direction must be maintained with very high accuracy during each observation.In this study,the spatial geometrical relationship between the four spacecraft was established by introducing the parameters of lengths,angles,and a reference vector.The first contribution is that a compact set of normalized factors and critical time indices are defined,which can provide a complete description of the drift of the shape and pointing direction of the configuration,caused by the unstable dynamical environment.Five design variables are isolated and analyzed,and their individual impacts on the uncontrolled evolution of the formation are studied.The main results obtained reveal that the dimensions of the rigid configuration allow a free drift for a time period on the order of tens of hours,while the inertial pointing direction will be lost within merely tens of seconds.Therefore,to form a rigid configuration,the control challenge lies in the fact that control efforts are frequently required for each spacecraft in the fleet,owing to the diverging dynamics.As a second contribution,a simple and feasible control algorithm is proposed to maintain the rigidity of the formation configuration.The results indicate that the associated energy cost is merely 0.05 m/s per observation on average.展开更多
Formation flying is a novel concept of distributing the functionality of large spacecraft among several smaller, less expensive, cooperative satellites. Some applications require that a controllable satellite keeps re...Formation flying is a novel concept of distributing the functionality of large spacecraft among several smaller, less expensive, cooperative satellites. Some applications require that a controllable satellite keeps relative position and attitude to observe a specific surface of another satellite among the cluster. Specially, the target space vehicle is malfunctioning. The present paper focuses on the problem that how to control a chaser satellite to fly around an out-of-work target satellite closely in earth orbit and to track a specific surface. Relative attitude and first approximate relative orbital dynamics equations are presented. Control strategy is derived based on feedback linearization and Lyapunov theory of stability. Further, considering the uncertainty of inertia, an adaptive control method is developed to obtain the correct inertial ratio. The numerical simulation is given to verify the validity of proposed control scheme.展开更多
The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our prev...The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our previous work,a novel industrial p-xylene oxidation reactor model using the free radical mechanism based kinetics has been developed.However,the disturbances such as production rate change,feed composition variability and reactor temperature changes widely exist in the industry process.In this paper,dynamic simulation of the PX oxidation reactor was designed by Aspen Dynamics and used to develop an effective plantwide control structure,which was capable of effectively handling the disturbances in the load and the temperature of the reactor.Step responses of the control structure to the disturbances were shown and served as the foundation of the smooth operation and advanced control strategy of this process in our future work.展开更多
In the process of urbanization, the construction industry has also entered a new stage of development. In the construction of construction projects, project cost is one of the most critical parts to realize the econom...In the process of urbanization, the construction industry has also entered a new stage of development. In the construction of construction projects, project cost is one of the most critical parts to realize the economic benefits of enterprises, which is closely related to the development of enterprises and the return on investment. At present, there are still some deficiencies in the management of construction project cost in our country. Enterprises must carry out dynamic management and control of construction cost in order to promote the good development of enterprises. Based on this, this paper expounds some measures to optimize the dynamic management and control of engineering cost, so as to bring new vitality to the development of the construction industry.展开更多
In order to improve the quality of automatic monitoring data of pollution sources and apply the automatic monitoring data to verify the environmental tax,Shandong Province took the lead in adopting the Internet of Thi...In order to improve the quality of automatic monitoring data of pollution sources and apply the automatic monitoring data to verify the environmental tax,Shandong Province took the lead in adopting the Internet of Things technology and drawing on the successful experience of air automatic monitoring stations and surface water automatic monitoring stations in management,and developed a dynamic management and control system for automatic monitoring equipment of pollution sources to improve and strengthen the quality audit of automatic monitoring data,further improve the quality of automatic monitoring data and better provide a basis for environmental management and decision making.The system realizes the simultaneous monitoring of monitoring data,running state and parameters of the automatic monitoring equipment,eliminates the phenomenon of falsification by modifying equipment parameters,and judges the validity of the collected data by acquiring the working state of the equipment remotely and randomly.After the actual operation test of the Department of Ecological Environment of Shandong Province,the system is proved to have the characteristics of practicality,real time and high efficiency,and be able to make up for low frequency and narrow coverage of manual inspection,with good application prospect in the field of environment and pollution source monitoring.展开更多
Automatic monitoring data of pollution sources is an important basis for environmental supervision and management.At present,it is difficult to guarantee the quality of automatic monitoring data of pollution sources,a...Automatic monitoring data of pollution sources is an important basis for environmental supervision and management.At present,it is difficult to guarantee the quality of automatic monitoring data of pollution sources,and it is difficult to play the role of the monitoring data.In response to this problem,the factors influencing the quality of automatic monitoring data of pollution sources were analyzed in detail,and technical assurance measures for the quality of automatic monitoring data of pollution sources in Shandong Province were studied.Besides,the dynamic management and control idea of automatic monitoring of pollution sources was proposed,and specific technical measures were analyzed from five aspects of standardizing automatic monitoring equipment of pollution sources,improving the data collection and transmission system,establishing a mechanism for reporting operating status information of monitoring equipment,setting alarm rules and alarm processing procedures,and statistically analyzing the operating status of the equipment.Practice has proved that the dynamic management and control system can effectively ensure the quality of automatic monitoring data of pollution sources.展开更多
The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset fron...The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset frontal vehicle-to-vehicle collision. A unique 6-degree-of- freedom （6-DOF） vehicle dynamics/crash mathematical model and a simplified lumped mass occupant model are developed. The first model is used to define the vehicle body crash parameters and it integrates a vehicle dynamics model with a vehicle front-end structure model. The second model aims to predict the effect of VDCS on the kinematics of the occupant. It is shown from the numerical simulations that the vehicle dynamics/crash response and occupant behaviour can be captured and analysed quickly and accurately. Yurthermore, it is shown that the VDCS can affect the crash characteristics positively and the occupant behaviour is improved.展开更多
Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes mu...Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes much contribution.When the size of complex surfaces is large or the machining space is narrow,the multi-axis NC machining may not be a good choice because of its high cost and low dexterity.Robotic machining is a beneficial supplement to the NC machining.Since it has the advantages of large operating space,good dexterity,and easy to realize parallel machining,it is a promising technique to enhance the capability of traditional NC machining.However,whether it is the multi-axis NC machining or the robotic machining,owing to the complex geometric properties and strict machining requirements,high-efficiency and high-accuracy machining of complex surfaces has always been a great challenge and remains a cutting-edge problem in the current manufacturing field.In this paper,by surveying the machining of complex parts and large complex surfaces,the theory and technology of high-efficiency and high-accuracy machining of complex surfaces are reviewed thoroughly.Then,a series of typical applications are introduced to show the state-of-the-art on the machining of complex surfaces,especially the recently developed industrial software and equipment.Finally,the summary and prospect of the machining of complex surfaces are addressed.To the best of our knowledge,this may be the first attempt to systematically review the machining of complex surfaces by the multiaxis NC and robotic machining techniques,in order to promote the further research in related fields.展开更多
Purpose–This study aims to investigate the safety effects of work zone advisory systems.The traditional system includes a dynamic message sign(DMS),whereas the advanced system includes an in-vehicle work zone warning...Purpose–This study aims to investigate the safety effects of work zone advisory systems.The traditional system includes a dynamic message sign(DMS),whereas the advanced system includes an in-vehicle work zone warning application under the connected vehicle(CV)environment.Design/methodology/approach–A comparative analysis was conducted based on the microsimulation experiments.Findings–The results indicate that the CV-based warning system outperforms the DMS.From this study,the optimal distances of placing a DMS varies according to different traffic conditions.Nevertheless,negative influence of excessive distance DMS placed from the work zone would be more obvious when there is heavier traffic volume.Thus,it is recommended that the optimal distance DMS placed from the work zone should be shortened if there is a traffic congestion.It was also revealed that higher market penetration rate of CVs will lead to safer network under good traffic conditions.Research limitations/implications–Because this study used only microsimulation,the results do not reflect the real-world drivers’reactions to DMS and CV warning messages.A series of driving simulator experiments need to be conducted to capture the real driving behaviors so as to investigate the unresolved-related issues.Human machine interface needs be used to simulate the process of in-vehicle warning information delivery.The validation of the simulation model was not conducted because of the data limitation.Practical implications–It suggests for the optimal DMS placement for improving the overall efficiency and safety under the CV environment.Originality/value–A traffic network evaluation method considering both efficiency and safety is proposed by applying traffic simulation.展开更多
文摘The research on spatial epidemic models is a topic of considerable recent interest. In another hand, the advances in computer technology have stimulated the development of stochastic models. Metapopulation models are spatial designs that involve movements of individuals between distinct subpopulations. The purpose of the present work has been to develop stochastic models in order to study the transmission dynamics and control of infectious diseases in metapopulations. The authors studied Susceptible-Infected-Susceptible （SIS） and Susceptible-lnfected-Recovered （SIR） epidemic schemes, using the Gillespie algorithm, Computational numerical simulations were carried in order to explore the models. The results obtained show how the dynamics of transmission and the application of control measures within each subpopulation may affect all subpopulations of the system. They also show how the distribution of control measures among subpopulations affects the efficacy of these strategies. The dynamics of the stochastic models developed in the current study follow the trends observed in the classic deterministic designs. Also, the present models exhibit fluctuating behavior. This work highlights the importance of the spatial distribution of the population in spread and control of infectious diseases. In addition, it shows how chance could play an important role in these scenarios.
文摘Animal flight and swimming have long been of great interest to people.Besides curiosity about how their sophisticated aero-and hydrodynamic feats are performed,researches are very interested in the mechanics of animal flight and swimming for the following two reasons.One is that biologists need to understand the effects of aero-and hydrodynamic force production and energy expenditure on the physiology,behavior,evolution and other aspects of the animals.The
文摘Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the modeling of dynamics environment and the orbital dynamics mechanism. This paper introduced state-ofthe-art researches, major challenges, and future trends in this field. Three topics are mainly discussed： the gravitational field modeling of irregular-shaped small celestial bodies, natural orbital dynamics and control, and controlled orbital dynamics. Finally, constructive suggestions are made for China’s future space exploration missions.
基金The authors would like to appreciate the anonymous reviewers for giving valuable advice to help in improving the quality of the paper.This study was supported by the National Natural Science Foundation of China(Nos.11602297,11902027,and 62173334).
文摘The dynamics and control of a tetrahedral spacecraft formation flying in the Sun-Earth L2 region is initiatively studied,based on the circular restricted three-body problem(CR3BP).Driven by the science goal of identifying extra-solar terrestrial planets and the requirement of imaging optics,a conceptional four-spacecraft triangular pyramid configuration has been proposed for the Multiple-spacecraft Exoplanet Aperture sYnthetic INterferometer(MEAYIN)project,China’s first mid-infrared interferometric imaging mission.Although it looked promising from an optical perspective,the configuration has not been verified dynamically.The formation is required to be virtually“rigid”,because its mutual distances and inertial pointing direction must be maintained with very high accuracy during each observation.In this study,the spatial geometrical relationship between the four spacecraft was established by introducing the parameters of lengths,angles,and a reference vector.The first contribution is that a compact set of normalized factors and critical time indices are defined,which can provide a complete description of the drift of the shape and pointing direction of the configuration,caused by the unstable dynamical environment.Five design variables are isolated and analyzed,and their individual impacts on the uncontrolled evolution of the formation are studied.The main results obtained reveal that the dimensions of the rigid configuration allow a free drift for a time period on the order of tens of hours,while the inertial pointing direction will be lost within merely tens of seconds.Therefore,to form a rigid configuration,the control challenge lies in the fact that control efforts are frequently required for each spacecraft in the fleet,owing to the diverging dynamics.As a second contribution,a simple and feasible control algorithm is proposed to maintain the rigidity of the formation configuration.The results indicate that the associated energy cost is merely 0.05 m/s per observation on average.
基金Project supported by the National Natural Science Foundation of China(No.10672084)the Specialized Research Fund for Doctoral Program of Higher Education(No.20060003097)
文摘Formation flying is a novel concept of distributing the functionality of large spacecraft among several smaller, less expensive, cooperative satellites. Some applications require that a controllable satellite keeps relative position and attitude to observe a specific surface of another satellite among the cluster. Specially, the target space vehicle is malfunctioning. The present paper focuses on the problem that how to control a chaser satellite to fly around an out-of-work target satellite closely in earth orbit and to track a specific surface. Relative attitude and first approximate relative orbital dynamics equations are presented. Control strategy is derived based on feedback linearization and Lyapunov theory of stability. Further, considering the uncertainty of inertia, an adaptive control method is developed to obtain the correct inertial ratio. The numerical simulation is given to verify the validity of proposed control scheme.
基金Supported by the Major State Basic Research Development Program of China(2012CB720500)the National Natural Science Foundation of China(U1162202)+2 种基金the Shanghai Second Polytechnic University Key Discipline Construction(4th term)-Control Theory&Control Engineering(XXKPY1308)the Cultivation Program of Young Teachers in Colleges and Universities of Shanghai(ZZegdl4013)the School Foundation of Shanghai Second Polytechnic University(EGD14XQD02)
文摘The p-xylene(PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber.A steady-state model of the PX oxidation has been studied by many researchers.In our previous work,a novel industrial p-xylene oxidation reactor model using the free radical mechanism based kinetics has been developed.However,the disturbances such as production rate change,feed composition variability and reactor temperature changes widely exist in the industry process.In this paper,dynamic simulation of the PX oxidation reactor was designed by Aspen Dynamics and used to develop an effective plantwide control structure,which was capable of effectively handling the disturbances in the load and the temperature of the reactor.Step responses of the control structure to the disturbances were shown and served as the foundation of the smooth operation and advanced control strategy of this process in our future work.
文摘In the process of urbanization, the construction industry has also entered a new stage of development. In the construction of construction projects, project cost is one of the most critical parts to realize the economic benefits of enterprises, which is closely related to the development of enterprises and the return on investment. At present, there are still some deficiencies in the management of construction project cost in our country. Enterprises must carry out dynamic management and control of construction cost in order to promote the good development of enterprises. Based on this, this paper expounds some measures to optimize the dynamic management and control of engineering cost, so as to bring new vitality to the development of the construction industry.
文摘In order to improve the quality of automatic monitoring data of pollution sources and apply the automatic monitoring data to verify the environmental tax,Shandong Province took the lead in adopting the Internet of Things technology and drawing on the successful experience of air automatic monitoring stations and surface water automatic monitoring stations in management,and developed a dynamic management and control system for automatic monitoring equipment of pollution sources to improve and strengthen the quality audit of automatic monitoring data,further improve the quality of automatic monitoring data and better provide a basis for environmental management and decision making.The system realizes the simultaneous monitoring of monitoring data,running state and parameters of the automatic monitoring equipment,eliminates the phenomenon of falsification by modifying equipment parameters,and judges the validity of the collected data by acquiring the working state of the equipment remotely and randomly.After the actual operation test of the Department of Ecological Environment of Shandong Province,the system is proved to have the characteristics of practicality,real time and high efficiency,and be able to make up for low frequency and narrow coverage of manual inspection,with good application prospect in the field of environment and pollution source monitoring.
文摘Automatic monitoring data of pollution sources is an important basis for environmental supervision and management.At present,it is difficult to guarantee the quality of automatic monitoring data of pollution sources,and it is difficult to play the role of the monitoring data.In response to this problem,the factors influencing the quality of automatic monitoring data of pollution sources were analyzed in detail,and technical assurance measures for the quality of automatic monitoring data of pollution sources in Shandong Province were studied.Besides,the dynamic management and control idea of automatic monitoring of pollution sources was proposed,and specific technical measures were analyzed from five aspects of standardizing automatic monitoring equipment of pollution sources,improving the data collection and transmission system,establishing a mechanism for reporting operating status information of monitoring equipment,setting alarm rules and alarm processing procedures,and statistically analyzing the operating status of the equipment.Practice has proved that the dynamic management and control system can effectively ensure the quality of automatic monitoring data of pollution sources.
基金the Egyptian government and the Faculty of Engineering,Ain Shams University for supporting this research
文摘The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset frontal vehicle-to-vehicle collision. A unique 6-degree-of- freedom （6-DOF） vehicle dynamics/crash mathematical model and a simplified lumped mass occupant model are developed. The first model is used to define the vehicle body crash parameters and it integrates a vehicle dynamics model with a vehicle front-end structure model. The second model aims to predict the effect of VDCS on the kinematics of the occupant. It is shown from the numerical simulations that the vehicle dynamics/crash response and occupant behaviour can be captured and analysed quickly and accurately. Yurthermore, it is shown that the VDCS can affect the crash characteristics positively and the occupant behaviour is improved.
基金supported by the National Natural Science Foundation of China(Grant Nos.52188102,52090054 and 52075205)。
文摘Complex surfaces are widely used in aerospace,energy,and national defense industries.As one of the major means of manufacturing such as complex surfaces,the multi-axis numerical control(NC)machining technique makes much contribution.When the size of complex surfaces is large or the machining space is narrow,the multi-axis NC machining may not be a good choice because of its high cost and low dexterity.Robotic machining is a beneficial supplement to the NC machining.Since it has the advantages of large operating space,good dexterity,and easy to realize parallel machining,it is a promising technique to enhance the capability of traditional NC machining.However,whether it is the multi-axis NC machining or the robotic machining,owing to the complex geometric properties and strict machining requirements,high-efficiency and high-accuracy machining of complex surfaces has always been a great challenge and remains a cutting-edge problem in the current manufacturing field.In this paper,by surveying the machining of complex parts and large complex surfaces,the theory and technology of high-efficiency and high-accuracy machining of complex surfaces are reviewed thoroughly.Then,a series of typical applications are introduced to show the state-of-the-art on the machining of complex surfaces,especially the recently developed industrial software and equipment.Finally,the summary and prospect of the machining of complex surfaces are addressed.To the best of our knowledge,this may be the first attempt to systematically review the machining of complex surfaces by the multiaxis NC and robotic machining techniques,in order to promote the further research in related fields.
基金funded by National Key R&D Program of China(2020YFB1600400)Innovation-Driven Project of Central South University(2020CX013)Shanghai Sailing Program(19YF1451300).
文摘Purpose–This study aims to investigate the safety effects of work zone advisory systems.The traditional system includes a dynamic message sign(DMS),whereas the advanced system includes an in-vehicle work zone warning application under the connected vehicle(CV)environment.Design/methodology/approach–A comparative analysis was conducted based on the microsimulation experiments.Findings–The results indicate that the CV-based warning system outperforms the DMS.From this study,the optimal distances of placing a DMS varies according to different traffic conditions.Nevertheless,negative influence of excessive distance DMS placed from the work zone would be more obvious when there is heavier traffic volume.Thus,it is recommended that the optimal distance DMS placed from the work zone should be shortened if there is a traffic congestion.It was also revealed that higher market penetration rate of CVs will lead to safer network under good traffic conditions.Research limitations/implications–Because this study used only microsimulation,the results do not reflect the real-world drivers’reactions to DMS and CV warning messages.A series of driving simulator experiments need to be conducted to capture the real driving behaviors so as to investigate the unresolved-related issues.Human machine interface needs be used to simulate the process of in-vehicle warning information delivery.The validation of the simulation model was not conducted because of the data limitation.Practical implications–It suggests for the optimal DMS placement for improving the overall efficiency and safety under the CV environment.Originality/value–A traffic network evaluation method considering both efficiency and safety is proposed by applying traffic simulation.
