Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to i...Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to investigate the dominant technology by exploring its formation process and mechanism.Specifically,based on complex adaptive system theory and the basic stimulus-response model,we use a combination of agent-based modeling and system dynamics modeling to capture the interactions between dominant technology and the socio-technical landscape.The results indicate the following:(i)The dynamic interaction is“stimulus-reaction-selection”,which promotes the dominant technology’s formation.(ii)The dominant technology’s formation can be described as a dynamic process in which the adaptation intensity of technology standards increases continuously until it becomes the leading technology under the dual action of internal and external mechanisms.(iii)The dominant technology’s formation in the high-tech industry is influenced by learning ability,the number of adopting users and adaptability.Therein,a“critical scale”of learning ability exists to promote the formation of leading technology:a large number of adopting users can promote the dominant technology’s formation by influencing the adaptive response of technology standards to the socio-technical landscape and the choice of technology standards by the socio-technical landscape.There is a minimum threshold and a maximum threshold for the role of adaptability in the dominant technology’s formation.(iv)The socio-technical landscape can promote the leading technology’s shaping in the high-tech industry,and different elements have different effects.This study promotes research on the formation mechanism of dominant technology in the high-tech industry,presents new perspectives and methods for researchers,and provides essential enlightenment for managers to formulate technology strategies.展开更多
Computer simulation models may by used to gain further information about missile performance variability. Model validation is an important aspect of the test program for a missile system. Validation provides a basis f...Computer simulation models may by used to gain further information about missile performance variability. Model validation is an important aspect of the test program for a missile system. Validation provides a basis for confidence in the model's results and is a necessary step if the model is to be used to draw inference about the behavior of the real missile. This paper is a review of methods useful for validation of computer simulation models of missile systems and provides a new method with high degree of confidence for validation of computer simulation models of missile systems. Some examples of the use of the new method in validating computer simulation models are given.展开更多
Combat system effectiveness simulation (CSES) is a special type of complex system simulation. Three non-functional requirements (NFRs), i.e. model composability, domain specific modeling, and model evolvability, are g...Combat system effectiveness simulation (CSES) is a special type of complex system simulation. Three non-functional requirements (NFRs), i.e. model composability, domain specific modeling, and model evolvability, are gaining higher priority from CSES users when evaluating different modeling methodologies for CSES. Traditional CSES modeling methodologies are either domain-neutral (lack of domain characteristics consideration and limited support for model composability) or domain-oriented (lack of openness and evolvability) and fall short of the three NFRs. Inspired by the concept of architecture in systems engineering and software engineering fields, we extend it into a concept of model architecture for complex simulation systems, and propose a model architecture-oriented modeling methodology in which the model architecture plays a central role in achieving the three NFRs. Various model-driven engineering (MDE) approaches and technologies, including simulation modeling platform (SMP), unified modeling language (UML), domain specific modeling (DSM), eclipse modeling framework (EMF), graphical modeling framework (GMF), and so forth, are applied where possible in representing the CSES model architecture and its components' behaviors from physical and cognitive domain aspects. A prototype CSES system, called weapon effectiveness simulation system (WESS), and a non-trivial air-combat simulation example are presented to demonstrate the methodology.展开更多
OBJECTIVE To explain the high inter-individual variability and the frequency of exceeding the therapeutic reference range and the laboratory alert level of amisulpride,a popula⁃tion pharmacokinetic model in Chinese pa...OBJECTIVE To explain the high inter-individual variability and the frequency of exceeding the therapeutic reference range and the laboratory alert level of amisulpride,a popula⁃tion pharmacokinetic model in Chinese patients with schizophrenia was built based on therapeu⁃tic drug monitoring data to guide individualized therapy.METHODS Plasma concentration data(330 measurements from 121 patients)were ana⁃lyzed using a nonlinear mixed-effects model⁃ing approach with first-order conditional estima⁃tion with interaction(FOCE I).The concentra⁃tions of amisulpride were detected by HPLC-MS/MS.Age,weight,sex,combination medication history and renal function status were evaluated as main covariates.The model was internally val⁃idated using goodness-of-fit,bootstrap and nor⁃malized prediction distribution error.Recom⁃mended dosage regimens for patients with key covariates were estimated on the basis of Monte Carlo simulations and the established model.RESULTS A one-compartment model with first-order absorption and elimination was found to adequately characterize amisulpride concentra⁃tion in Chinese patients with schizophrenia.The population estimates of the apparent volume of distribution(V/F)and apparent clearance(CL/F)were 12.7 L and 1.12 L·h-1,respectively.Age sig⁃nificantly affected the clearance of amisulpride and the final model was as follow:CL/F=1.04×(AGE/32)-0.624(L·h-1).To avoid exceeding the lab⁃oratory alert level(640μg·L-1),the model-based simulation results showed that the recommended dose of amisulpride was no more than 600 mg per day for patients aged 60 years,800 mg per day for those aged 40 years and 1200 mg per day for those aged 20 years,respectively.CON⁃CLUSION Dosage optimization of amisulpride can be carried out according to age to reduce the risk of adverse reactions.The model can be used as a suitable tool for designing individual⁃ized therapy for Chinese patients with schizo⁃phrenia.展开更多
To makesystem-of-systems combat simulation models easy to be developed and reused, simulation model formal specification and representation are researched. According to the view of system-of-systems combat simulation,...To makesystem-of-systems combat simulation models easy to be developed and reused, simulation model formal specification and representation are researched. According to the view of system-of-systems combat simulation, and based on DEVS, the simulation model＇s fundamental formalisms are explored. It includes entity model, system-of-systems model and experiment model. It also presents rigorous formal specification. XML data exchange standard is combined to design the XML based language, SCSL, to support simulation model representation. The corresponding relationship between SCSL and simulation model formalism is discussed and the syntax and semantics of elements in SCSL are detailed. Based on simulation model formal specification, the abstract simulation algorithm is given and SCSL virtual machine, which is capable of automatically interpreting and executing simulation model represented by SCSL, is designed. Finally an application case is presented, which can show the validation of the theory and verification of SCSL.展开更多
Multi-disciplinary virtual prototypes of complex products are increasingly and widely used in modern advanced manufactur- ing. How to effectively address the problems of unified modeling, composition and reuse based o...Multi-disciplinary virtual prototypes of complex products are increasingly and widely used in modern advanced manufactur- ing. How to effectively address the problems of unified modeling, composition and reuse based on the multi-disciplinary heteroge- neous models has brought great challenges to the modeling and simulation （M＆S） science and technology. This paper presents a top-level modeling theory based on the meta modeling framework （M2F） of the COllaborative SIMulation （COSlM） theory of virtual prototyping to solve the problems. Firstly the fundamental prin- ciples of the top-level modeling theory are decribed to expound the premise, assumptions, basic conventions and special require- ments in the description of complex heterogeneous systems. Next the formalized definitions for each factor in top level modeling are proposed and the hierarchical nature of them is illustrated. After demonstrating that they are self-closing, this paper divides the top- level modeling into two views, static structural graph and dynamic behavioral graph. Finally, a case study is discussed to demon- strate the feasibility of the theory.展开更多
This paper will develop a model simulation mixing traffic flow in the signal controlintersection. Applying the model, the schemes of traffic channeling and controlling in the typical intersection are analyzed and opti...This paper will develop a model simulation mixing traffic flow in the signal controlintersection. Applying the model, the schemes of traffic channeling and controlling in the typical intersection are analyzed and optimized and the optimal scheme make the average stop frequency be reduced by 31.8% and average stop time be reduced by 27.7%.展开更多
Volumetric efficiency and air charge estimation is one of the most demanding tasks in control of today's internal combustion engines.Specifically,using three-way catalytic converter involves strict control of the ...Volumetric efficiency and air charge estimation is one of the most demanding tasks in control of today's internal combustion engines.Specifically,using three-way catalytic converter involves strict control of the air/fuel ratio around the stoichiometric point and hence requires an accurate model for air charge estimation.However,high degrees of complexity and nonlinearity of the gas flow in the internal combustion engine make air charge estimation a challenging task.This is more obvious in engines with variable valve timing systems in which gas flow is more complex and depends on more functional variables.This results in models that are either quite empirical(such as look-up tables),not having interpretability and extrapolation capability,or physically based models which are not appropriate for onboard applications.Solving these problems,a novel semi-empirical model was proposed in this work which only needed engine speed,load,and valves timings for volumetric efficiency prediction.The accuracy and generalizability of the model is shown by its test on numerical and experimental data from three distinct engines.Normalized test errors are 0.0316,0.0152 and 0.24 for the three engines,respectively.Also the performance and complexity of the model were compared with neural networks as typical black box models.While the complexity of the model is less than half of the complexity of neural networks,and its computational cost is approximately 0.12 of that of neural networks and its prediction capability in the considered case studies is usually more.These results show the superiority of the proposed model over conventional black box models such as neural networks in terms of accuracy,generalizability and computational cost.展开更多
To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they ...To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.展开更多
The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away fro...The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away from the engineering practice. The experimental methods are time-consuming and financial expensive, even unrealizable due to the lack of suitable sensors. Numerical simulations can bridge the gap between the theoretical analysis and experimental techniques. A complete overall dynamic model of maglev levitation system is derived in this work, which includes the simple-supported bridges, the calculation of electromagnetic force with more details, the stress of levitation modules and the cabin. Based on the aforementioned model, it shows that the inherent nonlinearity, inner coupling, misalignments between the sensors and actuators, and self-excited vibration are the main issues that should be considered during the design process of controller. Then, the backstepping controller based on the mathematical model of the module with reasonable simplifications is proposed, and the stability proofs are listed. To show the advantage of controller, two numerical simulation experiments are carried out. Finally, the results illustrating closed-loop performance are provided.展开更多
Aiming at the fact that the energy and mass exchange phenomena exist between barrel and gas-operated device of the automatic weapon, for describing its interior ballistics and dynamic characteristics of the gas-operat...Aiming at the fact that the energy and mass exchange phenomena exist between barrel and gas-operated device of the automatic weapon, for describing its interior ballistics and dynamic characteristics of the gas-operated device accurately, a new variable-mass thermodynamics model is built. It is used to calculate the automatic mechanism velocity of a certain automatic weapon, the calculation results coincide with the experimental results better, and thus the model is validated. The influences of structure parameters on gas-operated device's dynamic characteristics are discussed. It shows that the model is valuable for design and accurate performance prediction of gas-operated automatic weapon.展开更多
In order to study the major performance indicators of the twin-rotor piston engine(TRPE), Matlab/simulink was used to simulate the mathematical models of its thermodynamic processes. With consideration of the characte...In order to study the major performance indicators of the twin-rotor piston engine(TRPE), Matlab/simulink was used to simulate the mathematical models of its thermodynamic processes. With consideration of the characteristics of the working processes in the TRPE, corresponding differential equations were established and then simplified by period features of the TRPE. Finally, the major boundary conditions were figured out. The changing trends of mass, pressure and temperature of working fuel in the working chamber during a complete engine cycle were presented. The simulation results are consistent with the trends of an actual working cycle in the TRPE, which indicates that the method of simulation is feasible. As the pressure in the working chamber is calculated, all the performance parameters of the TRPE can be obtained. The major performance indicators, such as the indicated mean effective pressure, power to weight ratio and the volume power, are also acquired. Compared with three different types of conventional engines, the TRPE has a bigger utilization ratio of cylinder volume, a higher power to weight ratio and a more compact structure. This indicates that TRPE is superior to conventional engines.展开更多
Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching p...Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching process, the thermodynamics and kinetics characteristics of the system with three valves of different flow characteristics were got. The simulation results show that the values of the peak-to-average ratios of dimensionless acceleration with the equal percentage valve, the linear valve and the quick opening valve are 1.355, 1.614 and 1.722, respectively, and the final values of the dimensionless velocities are 0.843, 0.957 and 1.0, respectively. In conclusion, the value of the dimensionless velocity with the equal percentage valve doesn't reach the set value of 0.90 when the dimensionless displacement is 0.82, while the system with the linear valve can meet the launching requirement, as well as the fluctuation range of dimensionless acceleration is less than that of the quick opening valve. Therefore, the system with the linear valve has the best performance among the three kinds of valves.展开更多
城市用地空间扩张对生态环境的影响映射出人类社会活动和生态环境保护之间的交互作用,系统地研究城市空间无序蔓延所诱发的城市土地利用方式变化对城市生态环境的影响程度,对助推中国生态文明建设目标具有重要现实意义。为探究合肥市城...城市用地空间扩张对生态环境的影响映射出人类社会活动和生态环境保护之间的交互作用,系统地研究城市空间无序蔓延所诱发的城市土地利用方式变化对城市生态环境的影响程度,对助推中国生态文明建设目标具有重要现实意义。为探究合肥市城市扩张对生态安全格局的影响程度,综合运用生态遥感指数、最小累积阻力模型、电路理论和斑块生成土地利用模拟模型,构建合肥市生态安全格局,识别生态夹点和生态障碍点,再从模拟验证的基础上(总体精度为94.71%,Kappa系数为90.04%,Fom值为0.102),预测了2030—2040年的城市扩张,并根据预测结果探讨城市扩张对区域生态安全格局影响程度。研究发现:合肥市生态环境质量整体呈现南高中低的分布格局,识别出合肥市生态源地共计35处,源地间活跃生态廊道70条,非活跃廊道共17条,生态夹点290个,生态障碍点112个。2020—2040年合肥市城乡、工矿居民用地、林地、水域和未利用土地面积将不断增加,而耕地以及草地面积将持续减少。2020—2040年期间城镇建成区分别侵占了生态廊道、源地、夹点、障碍点面积为55.95、10.51、1.04、1.35 km 2。研究结果可为今后快速发展城市的生态环境治理和国土空间生态保护修复工作提供理论依据和技术参考。展开更多
The simulation model Tunev（tunnel evacuation） was developed for people＇s evacuation in tunnel fire. It contains simple database of the people＇s behavioral reaction and structure characteristic parameters of tunnel...The simulation model Tunev（tunnel evacuation） was developed for people＇s evacuation in tunnel fire. It contains simple database of the people＇s behavioral reaction and structure characteristic parameters of tunnel fireproofing. The model can be used to calculate the total evacuation time in various scenes when fire occurs in the different locations of the tunnel. Combined with fire simulation soft ware CFD- POENICS3.5, Tunev model can be used to calculate the fire danger coming time; by comparing with these two kinds of time, it can be used to assess the safety of the evacuation, and the evacuation process also have a dynamic demo. The simulation results show that the Tunev model can be used to predict the reliability of safe evacuation for people in tunnel fire and provide references for people＇s safe escape scheme. Some relevant concepts of the model were described and an evacuation simulation of a typical tunnel case, i.e. Xuefeng Mountain Tunnel was performed by using this model. And the model＇s validation and actual aoolication were also described.展开更多
A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based ...A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based on the analysis on the cellular automata theory,and combining with on-site survey data,several key parameters were defined,namely,cellular length,cellular speed,cellular acceleration,updating time interval.In addition,cellular acceleration rule,cellular deceleration rule,random rule,lane-changing rule and other micro-simulation rules were set,and cellular automaton micro-simulation model was set up.Further-more,a micro-simulation module was developed for traffic operation actions of on-ramp junction with Matlab toolbox.Finally,a simulation experiment for traffic operation reliability was done with this micro-simulation module,and the situation of change for on-ramp junction area was obtained under the conditions of different mainline design speed,acceleration lane length,vehicle generation probability and lane-changing probability.The results show that operation reliability for on-ramp junction is determined by the parameters of the probability of vehicle generation and the length of acceleration lane,especially for on-ramp.展开更多
The interception probability of a single missile is the basis for combat plan design and weapon performance evaluation,while its influencing factors are complex and mutually coupled.Existing calculation methods have v...The interception probability of a single missile is the basis for combat plan design and weapon performance evaluation,while its influencing factors are complex and mutually coupled.Existing calculation methods have very limited analysis of the influence mechanism of influencing factors,and none of them has analyzed the influence of the guidance law.This paper considers the influencing factors of both the interceptor and the target more comprehensively.Interceptor parameters include speed,guidance law,guidance error,fuze error,and fragment killing ability,while target performance includes speed,maneuverability,and vulnerability.In this paper,an interception model is established,Monte Carlo simulation is carried out,and the influence mechanism of each factor is analyzed based on the model and simulation results.Finally,this paper proposes a classification-regression neural network to quickly estimate the interception probability based on the value of influencing factors.The proposed method reduces the interference of invalid interception data to valid data,so its prediction accuracy is significantly better than that of pure regression neural networks.展开更多
Switching expansion reduction(SER)uses a switch valve instead of the throttle valve to realize electronically controlled pressure reduction for high pressure pneumatics.A comprehensive and interactive pneumatic simula...Switching expansion reduction(SER)uses a switch valve instead of the throttle valve to realize electronically controlled pressure reduction for high pressure pneumatics.A comprehensive and interactive pneumatic simulation model according to the experimental setup of SER has been built.The mathematical model considers heat exchanges,source air pressure and temperature,environmental temperatures and heat transfer coefficients variations.In addition,the compensation for real gas effect is used in the model building.The comparison between experiments and simulations of SER indicates that,to compensate the real gas effect in high pressure discharging process,the thermal capacity of air supply container in simulation should be less than the actual value.The higher the pressure range,the greater the deviation.Simulated and experimental results are highly consistent within pressure reduction ratios ranging from 1.4 to 20 and output air mass flow rates ranging from 3.5 to 132 g/s,which verifies the high adaptability of SER and the validity of the mathematic model and the compensation method.展开更多
It is noted that any variation in operating conditions has a considerable effect on the tire/road interaction. Furthermore,choosing a range of proper values for carcass stiffness is very essential for both tire safety...It is noted that any variation in operating conditions has a considerable effect on the tire/road interaction. Furthermore,choosing a range of proper values for carcass stiffness is very essential for both tire safety and effective driving action. In this work,an elaborated 3D model fully compliant with the geometrical size of radial tire 185/60 R15 is worked up, for evaluating the effects of components properties and working conditions on deformation and stress/strain fields created inside the tire. For the simulation, the tire structure is assumed to be composed of tread, carcass ply, and bead. The mechanical behavior of rubber as main component of tire is described by Mooney-Rivlin material model. The comparison of the obtained results and laboratory tests demonstrates the validity and high accuracy of analysis.展开更多
基金supported by the Shanghai Philosophy and Social Science Foundation(2022ECK004)Shanghai Soft Science Research Project(23692123400)。
文摘Dominant technology formation is the key for the hightech industry to“cross the chasm”and gain an established foothold in the market(and hence disrupt the regime).Therefore,a stimulus-response model is proposed to investigate the dominant technology by exploring its formation process and mechanism.Specifically,based on complex adaptive system theory and the basic stimulus-response model,we use a combination of agent-based modeling and system dynamics modeling to capture the interactions between dominant technology and the socio-technical landscape.The results indicate the following:(i)The dynamic interaction is“stimulus-reaction-selection”,which promotes the dominant technology’s formation.(ii)The dominant technology’s formation can be described as a dynamic process in which the adaptation intensity of technology standards increases continuously until it becomes the leading technology under the dual action of internal and external mechanisms.(iii)The dominant technology’s formation in the high-tech industry is influenced by learning ability,the number of adopting users and adaptability.Therein,a“critical scale”of learning ability exists to promote the formation of leading technology:a large number of adopting users can promote the dominant technology’s formation by influencing the adaptive response of technology standards to the socio-technical landscape and the choice of technology standards by the socio-technical landscape.There is a minimum threshold and a maximum threshold for the role of adaptability in the dominant technology’s formation.(iv)The socio-technical landscape can promote the leading technology’s shaping in the high-tech industry,and different elements have different effects.This study promotes research on the formation mechanism of dominant technology in the high-tech industry,presents new perspectives and methods for researchers,and provides essential enlightenment for managers to formulate technology strategies.
文摘Computer simulation models may by used to gain further information about missile performance variability. Model validation is an important aspect of the test program for a missile system. Validation provides a basis for confidence in the model's results and is a necessary step if the model is to be used to draw inference about the behavior of the real missile. This paper is a review of methods useful for validation of computer simulation models of missile systems and provides a new method with high degree of confidence for validation of computer simulation models of missile systems. Some examples of the use of the new method in validating computer simulation models are given.
基金supported by the National Natural Science Foundation of China(61273198)
文摘Combat system effectiveness simulation (CSES) is a special type of complex system simulation. Three non-functional requirements (NFRs), i.e. model composability, domain specific modeling, and model evolvability, are gaining higher priority from CSES users when evaluating different modeling methodologies for CSES. Traditional CSES modeling methodologies are either domain-neutral (lack of domain characteristics consideration and limited support for model composability) or domain-oriented (lack of openness and evolvability) and fall short of the three NFRs. Inspired by the concept of architecture in systems engineering and software engineering fields, we extend it into a concept of model architecture for complex simulation systems, and propose a model architecture-oriented modeling methodology in which the model architecture plays a central role in achieving the three NFRs. Various model-driven engineering (MDE) approaches and technologies, including simulation modeling platform (SMP), unified modeling language (UML), domain specific modeling (DSM), eclipse modeling framework (EMF), graphical modeling framework (GMF), and so forth, are applied where possible in representing the CSES model architecture and its components' behaviors from physical and cognitive domain aspects. A prototype CSES system, called weapon effectiveness simulation system (WESS), and a non-trivial air-combat simulation example are presented to demonstrate the methodology.
文摘OBJECTIVE To explain the high inter-individual variability and the frequency of exceeding the therapeutic reference range and the laboratory alert level of amisulpride,a popula⁃tion pharmacokinetic model in Chinese patients with schizophrenia was built based on therapeu⁃tic drug monitoring data to guide individualized therapy.METHODS Plasma concentration data(330 measurements from 121 patients)were ana⁃lyzed using a nonlinear mixed-effects model⁃ing approach with first-order conditional estima⁃tion with interaction(FOCE I).The concentra⁃tions of amisulpride were detected by HPLC-MS/MS.Age,weight,sex,combination medication history and renal function status were evaluated as main covariates.The model was internally val⁃idated using goodness-of-fit,bootstrap and nor⁃malized prediction distribution error.Recom⁃mended dosage regimens for patients with key covariates were estimated on the basis of Monte Carlo simulations and the established model.RESULTS A one-compartment model with first-order absorption and elimination was found to adequately characterize amisulpride concentra⁃tion in Chinese patients with schizophrenia.The population estimates of the apparent volume of distribution(V/F)and apparent clearance(CL/F)were 12.7 L and 1.12 L·h-1,respectively.Age sig⁃nificantly affected the clearance of amisulpride and the final model was as follow:CL/F=1.04×(AGE/32)-0.624(L·h-1).To avoid exceeding the lab⁃oratory alert level(640μg·L-1),the model-based simulation results showed that the recommended dose of amisulpride was no more than 600 mg per day for patients aged 60 years,800 mg per day for those aged 40 years and 1200 mg per day for those aged 20 years,respectively.CON⁃CLUSION Dosage optimization of amisulpride can be carried out according to age to reduce the risk of adverse reactions.The model can be used as a suitable tool for designing individual⁃ized therapy for Chinese patients with schizo⁃phrenia.
文摘To makesystem-of-systems combat simulation models easy to be developed and reused, simulation model formal specification and representation are researched. According to the view of system-of-systems combat simulation, and based on DEVS, the simulation model＇s fundamental formalisms are explored. It includes entity model, system-of-systems model and experiment model. It also presents rigorous formal specification. XML data exchange standard is combined to design the XML based language, SCSL, to support simulation model representation. The corresponding relationship between SCSL and simulation model formalism is discussed and the syntax and semantics of elements in SCSL are detailed. Based on simulation model formal specification, the abstract simulation algorithm is given and SCSL virtual machine, which is capable of automatically interpreting and executing simulation model represented by SCSL, is designed. Finally an application case is presented, which can show the validation of the theory and verification of SCSL.
基金supported by the National High Technology Research and Development Program (863 Program) (2011AA040502).
文摘Multi-disciplinary virtual prototypes of complex products are increasingly and widely used in modern advanced manufactur- ing. How to effectively address the problems of unified modeling, composition and reuse based on the multi-disciplinary heteroge- neous models has brought great challenges to the modeling and simulation （M＆S） science and technology. This paper presents a top-level modeling theory based on the meta modeling framework （M2F） of the COllaborative SIMulation （COSlM） theory of virtual prototyping to solve the problems. Firstly the fundamental prin- ciples of the top-level modeling theory are decribed to expound the premise, assumptions, basic conventions and special require- ments in the description of complex heterogeneous systems. Next the formalized definitions for each factor in top level modeling are proposed and the hierarchical nature of them is illustrated. After demonstrating that they are self-closing, this paper divides the top- level modeling into two views, static structural graph and dynamic behavioral graph. Finally, a case study is discussed to demon- strate the feasibility of the theory.
文摘This paper will develop a model simulation mixing traffic flow in the signal controlintersection. Applying the model, the schemes of traffic channeling and controlling in the typical intersection are analyzed and optimized and the optimal scheme make the average stop frequency be reduced by 31.8% and average stop time be reduced by 27.7%.
文摘Volumetric efficiency and air charge estimation is one of the most demanding tasks in control of today's internal combustion engines.Specifically,using three-way catalytic converter involves strict control of the air/fuel ratio around the stoichiometric point and hence requires an accurate model for air charge estimation.However,high degrees of complexity and nonlinearity of the gas flow in the internal combustion engine make air charge estimation a challenging task.This is more obvious in engines with variable valve timing systems in which gas flow is more complex and depends on more functional variables.This results in models that are either quite empirical(such as look-up tables),not having interpretability and extrapolation capability,or physically based models which are not appropriate for onboard applications.Solving these problems,a novel semi-empirical model was proposed in this work which only needed engine speed,load,and valves timings for volumetric efficiency prediction.The accuracy and generalizability of the model is shown by its test on numerical and experimental data from three distinct engines.Normalized test errors are 0.0316,0.0152 and 0.24 for the three engines,respectively.Also the performance and complexity of the model were compared with neural networks as typical black box models.While the complexity of the model is less than half of the complexity of neural networks,and its computational cost is approximately 0.12 of that of neural networks and its prediction capability in the considered case studies is usually more.These results show the superiority of the proposed model over conventional black box models such as neural networks in terms of accuracy,generalizability and computational cost.
基金Project(51175518)supported by the National Natural Science Foundation of China
文摘To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
基金Projects(60404003,11202230)supported by the National Natural Science Foundation of China
文摘The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away from the engineering practice. The experimental methods are time-consuming and financial expensive, even unrealizable due to the lack of suitable sensors. Numerical simulations can bridge the gap between the theoretical analysis and experimental techniques. A complete overall dynamic model of maglev levitation system is derived in this work, which includes the simple-supported bridges, the calculation of electromagnetic force with more details, the stress of levitation modules and the cabin. Based on the aforementioned model, it shows that the inherent nonlinearity, inner coupling, misalignments between the sensors and actuators, and self-excited vibration are the main issues that should be considered during the design process of controller. Then, the backstepping controller based on the mathematical model of the module with reasonable simplifications is proposed, and the stability proofs are listed. To show the advantage of controller, two numerical simulation experiments are carried out. Finally, the results illustrating closed-loop performance are provided.
文摘Aiming at the fact that the energy and mass exchange phenomena exist between barrel and gas-operated device of the automatic weapon, for describing its interior ballistics and dynamic characteristics of the gas-operated device accurately, a new variable-mass thermodynamics model is built. It is used to calculate the automatic mechanism velocity of a certain automatic weapon, the calculation results coincide with the experimental results better, and thus the model is validated. The influences of structure parameters on gas-operated device's dynamic characteristics are discussed. It shows that the model is valuable for design and accurate performance prediction of gas-operated automatic weapon.
基金Project(7131109)supported by the National Defense Pre-research Foundation of ChinaProject(51175500)supported by the National Natural Science Foundation of China
文摘In order to study the major performance indicators of the twin-rotor piston engine(TRPE), Matlab/simulink was used to simulate the mathematical models of its thermodynamic processes. With consideration of the characteristics of the working processes in the TRPE, corresponding differential equations were established and then simplified by period features of the TRPE. Finally, the major boundary conditions were figured out. The changing trends of mass, pressure and temperature of working fuel in the working chamber during a complete engine cycle were presented. The simulation results are consistent with the trends of an actual working cycle in the TRPE, which indicates that the method of simulation is feasible. As the pressure in the working chamber is calculated, all the performance parameters of the TRPE can be obtained. The major performance indicators, such as the indicated mean effective pressure, power to weight ratio and the volume power, are also acquired. Compared with three different types of conventional engines, the TRPE has a bigger utilization ratio of cylinder volume, a higher power to weight ratio and a more compact structure. This indicates that TRPE is superior to conventional engines.
基金Project(20080431380)supported by the National Postdoctoral Science Foundation,China
文摘Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching process, the thermodynamics and kinetics characteristics of the system with three valves of different flow characteristics were got. The simulation results show that the values of the peak-to-average ratios of dimensionless acceleration with the equal percentage valve, the linear valve and the quick opening valve are 1.355, 1.614 and 1.722, respectively, and the final values of the dimensionless velocities are 0.843, 0.957 and 1.0, respectively. In conclusion, the value of the dimensionless velocity with the equal percentage valve doesn't reach the set value of 0.90 when the dimensionless displacement is 0.82, while the system with the linear valve can meet the launching requirement, as well as the fluctuation range of dimensionless acceleration is less than that of the quick opening valve. Therefore, the system with the linear valve has the best performance among the three kinds of valves.
文摘城市用地空间扩张对生态环境的影响映射出人类社会活动和生态环境保护之间的交互作用,系统地研究城市空间无序蔓延所诱发的城市土地利用方式变化对城市生态环境的影响程度,对助推中国生态文明建设目标具有重要现实意义。为探究合肥市城市扩张对生态安全格局的影响程度,综合运用生态遥感指数、最小累积阻力模型、电路理论和斑块生成土地利用模拟模型,构建合肥市生态安全格局,识别生态夹点和生态障碍点,再从模拟验证的基础上(总体精度为94.71%,Kappa系数为90.04%,Fom值为0.102),预测了2030—2040年的城市扩张,并根据预测结果探讨城市扩张对区域生态安全格局影响程度。研究发现:合肥市生态环境质量整体呈现南高中低的分布格局,识别出合肥市生态源地共计35处,源地间活跃生态廊道70条,非活跃廊道共17条,生态夹点290个,生态障碍点112个。2020—2040年合肥市城乡、工矿居民用地、林地、水域和未利用土地面积将不断增加,而耕地以及草地面积将持续减少。2020—2040年期间城镇建成区分别侵占了生态廊道、源地、夹点、障碍点面积为55.95、10.51、1.04、1.35 km 2。研究结果可为今后快速发展城市的生态环境治理和国土空间生态保护修复工作提供理论依据和技术参考。
基金Project (20033179802) supported by the Science and Technology Programof China Western Transportation Development
文摘The simulation model Tunev（tunnel evacuation） was developed for people＇s evacuation in tunnel fire. It contains simple database of the people＇s behavioral reaction and structure characteristic parameters of tunnel fireproofing. The model can be used to calculate the total evacuation time in various scenes when fire occurs in the different locations of the tunnel. Combined with fire simulation soft ware CFD- POENICS3.5, Tunev model can be used to calculate the fire danger coming time; by comparing with these two kinds of time, it can be used to assess the safety of the evacuation, and the evacuation process also have a dynamic demo. The simulation results show that the Tunev model can be used to predict the reliability of safe evacuation for people in tunnel fire and provide references for people＇s safe escape scheme. Some relevant concepts of the model were described and an evacuation simulation of a typical tunnel case, i.e. Xuefeng Mountain Tunnel was performed by using this model. And the model＇s validation and actual aoolication were also described.
基金Project(HIT.NSRIF.2009102) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(11541295) supported by the Scientific Research Fund of Heilongjiang Provincial Education Department of ChinaProject(20100471029) supported by China Postdoctoral Science Foundation
文摘A disorder situation of traffic operation always appears in on-ramp junction area of urban freeway,because the operation action for vehicles presents the weaving condition,especially for different vehicle types.Based on the analysis on the cellular automata theory,and combining with on-site survey data,several key parameters were defined,namely,cellular length,cellular speed,cellular acceleration,updating time interval.In addition,cellular acceleration rule,cellular deceleration rule,random rule,lane-changing rule and other micro-simulation rules were set,and cellular automaton micro-simulation model was set up.Further-more,a micro-simulation module was developed for traffic operation actions of on-ramp junction with Matlab toolbox.Finally,a simulation experiment for traffic operation reliability was done with this micro-simulation module,and the situation of change for on-ramp junction area was obtained under the conditions of different mainline design speed,acceleration lane length,vehicle generation probability and lane-changing probability.The results show that operation reliability for on-ramp junction is determined by the parameters of the probability of vehicle generation and the length of acceleration lane,especially for on-ramp.
基金supported by the Foundation Strengthening Program Technology Field Foundation(2020-JCJQ-JJ-132)。
文摘The interception probability of a single missile is the basis for combat plan design and weapon performance evaluation,while its influencing factors are complex and mutually coupled.Existing calculation methods have very limited analysis of the influence mechanism of influencing factors,and none of them has analyzed the influence of the guidance law.This paper considers the influencing factors of both the interceptor and the target more comprehensively.Interceptor parameters include speed,guidance law,guidance error,fuze error,and fragment killing ability,while target performance includes speed,maneuverability,and vulnerability.In this paper,an interception model is established,Monte Carlo simulation is carried out,and the influence mechanism of each factor is analyzed based on the model and simulation results.Finally,this paper proposes a classification-regression neural network to quickly estimate the interception probability based on the value of influencing factors.The proposed method reduces the interference of invalid interception data to valid data,so its prediction accuracy is significantly better than that of pure regression neural networks.
基金Project(51205421)supported by the National Natural Science Foundation of ChinaProject(2012M521647)supported by the Postdoctoral Science Foundation of China
文摘Switching expansion reduction(SER)uses a switch valve instead of the throttle valve to realize electronically controlled pressure reduction for high pressure pneumatics.A comprehensive and interactive pneumatic simulation model according to the experimental setup of SER has been built.The mathematical model considers heat exchanges,source air pressure and temperature,environmental temperatures and heat transfer coefficients variations.In addition,the compensation for real gas effect is used in the model building.The comparison between experiments and simulations of SER indicates that,to compensate the real gas effect in high pressure discharging process,the thermal capacity of air supply container in simulation should be less than the actual value.The higher the pressure range,the greater the deviation.Simulated and experimental results are highly consistent within pressure reduction ratios ranging from 1.4 to 20 and output air mass flow rates ranging from 3.5 to 132 g/s,which verifies the high adaptability of SER and the validity of the mathematic model and the compensation method.
文摘It is noted that any variation in operating conditions has a considerable effect on the tire/road interaction. Furthermore,choosing a range of proper values for carcass stiffness is very essential for both tire safety and effective driving action. In this work,an elaborated 3D model fully compliant with the geometrical size of radial tire 185/60 R15 is worked up, for evaluating the effects of components properties and working conditions on deformation and stress/strain fields created inside the tire. For the simulation, the tire structure is assumed to be composed of tread, carcass ply, and bead. The mechanical behavior of rubber as main component of tire is described by Mooney-Rivlin material model. The comparison of the obtained results and laboratory tests demonstrates the validity and high accuracy of analysis.
