System dynamics (SD) theory has long been deployed in modeling complex non-linear interrelationships but, so far it has not been common to do the kind of modeling in support of bringing environmental sustainability po...System dynamics (SD) theory has long been deployed in modeling complex non-linear interrelationships but, so far it has not been common to do the kind of modeling in support of bringing environmental sustainability policies to practice. This is largely because the challenge of including spatial data has not yet been well met. Potential for adoption of SD and GIS methods in combination is exemplified with the results of a decision-support exercise designed for simulation and prediction of the dynamic inter-relationships between socio-economic development and environmental quality for the "Wen, Pi, Du" county in Sichuan province, southwestern China.展开更多
Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contri...Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contribution to mixture explosives.The work starts from the force-field derivation.We get ab initio based pair potentials across the interface,and then use them to study the interface structural and mechanical properties.A series of large scale molecular dynamics simulations are performed.The structure evolution,energy variation and elastic/plastic transformation of interface and polycrystal systems are calculated.The desensitizing mechanism of graphite to HMX is discussed.展开更多
Port-city system is a complex and integral system, and it can be simulated by system dynamic method, which is used to be employed to solve nonlinear problems. Based on the causality of the every element in the port-ci...Port-city system is a complex and integral system, and it can be simulated by system dynamic method, which is used to be employed to solve nonlinear problems. Based on the causality of the every element in the port-city system, the authors analyzed the feedback relation and logical relation among the system variables and system structure. A system-dynamic flow chart and correlation equations were put forward with VENSIM software, the quantitative relation was described, and the model was debugged. The development trend of the main influence factors in port-city system was simulated. By changing the influence degree of each related factor. It is found the parameters values of variables in the model, we studied that： 1） Foreign trade throughput of port play an important role in the development of export-oriented economy. 2） The development of primary industry and secondary industry affects most of the water transportation demand. With the constant increase of tertiary industry proportion in the industrial structure, the demand of national economy for water transportation decreases gradually. 3） Water transportation presents a kind of oversupply development situation, so port construction should properly slow down. 4） With the development of ports, its direct and indirect contribution to urban economy has been continuously increasing, but contribution rate will be continuously decreasing.展开更多
We perform langevin dynamics simulation for envelope solitons in an FPU-β lattice,with the nearestneighborinteraction and quartic anharmonicity.We get the motion equations of our discrete system by adding noiseand da...We perform langevin dynamics simulation for envelope solitons in an FPU-β lattice,with the nearestneighborinteraction and quartic anharmonicity.We get the motion equations of our discrete system by adding noiseand damping to the set of deterministic motion equations.We define'half-time'as the time when the amplitude of theenvelope soliton decreases by half due to damping.And then the mass,center and half-time of the perturbed envelopesoliton are numerically simulated,beginning with the discrete envelope soliton at rest.Results show successfully hownoise affects behavior of the envelope soliton.展开更多
The common properties of risk in long tunnel fires are high temperature, extreme difficulty of evacuation, rescue urgency and obstacle to rescue operation. Therefore, a complete ventilation design is an indispensable ...The common properties of risk in long tunnel fires are high temperature, extreme difficulty of evacuation, rescue urgency and obstacle to rescue operation. Therefore, a complete ventilation design is an indispensable safety measure. Hsueh-Shan Tunnel is the longest in Taiwan, the fifth longest in the world. On May 7, 2012, a serious tunnel fire caused two deaths and numerous victims suffered from smoke inhalation injury. Apart from this, there was smoking entering the cross-passages and shafts which were important for evacuation. In this research, the current ventilation system in Hsueh-Shan Tunnel was simulated with FDS （fire dynamics simulator） software, and the statistics of smoke, visibility and temperature profile were analyzed. The results of this research showed that, with the current ventilation system, the time was shorter and the distance was longer for the smoke spreading windward than in other models. Furthermore, the visibility of windward victims was more affected and the temperature above the fire source was higher than those in other systems. When the wind speed in tunnel is within 2.0-4.0 m/s, the condition for turning off the ventilation fan within 250 m upwind from the fire source can be prominently reduced to 50 m upwind from the fire source. This not only could avoid plume disturbance but also could be maintained. If victims＇ evacuation should be given the highest priority, it is recommended to straightly activate the maximum power of the fan.展开更多
In principle, non-Hermitian quantum equations of motion can be formulated using as a starting point either the Heisenberg＇s or the Schroedinger＇s picture of quantum dynamics. Here it is shown in both cases how to ma...In principle, non-Hermitian quantum equations of motion can be formulated using as a starting point either the Heisenberg＇s or the Schroedinger＇s picture of quantum dynamics. Here it is shown in both cases how to map the algebra of commutators, defining the time evolution in terms of a non-Hermitian Hamiltonian, onto a non-Hamiltonian algebra with a Hermitian Hamiltonian. The logic behind such a derivation is reversible, so that any Hermitian Hamiltonian can be used in the formulation of non-Hermitian dynamics through a suitable algebra of generalized （non-Hamiltonian） commutators. These results provide a general structure （a template） for non-Hermitian equations of motion to be used in the computer simulation of open quantum systems dynamics.展开更多
文摘System dynamics (SD) theory has long been deployed in modeling complex non-linear interrelationships but, so far it has not been common to do the kind of modeling in support of bringing environmental sustainability policies to practice. This is largely because the challenge of including spatial data has not yet been well met. Potential for adoption of SD and GIS methods in combination is exemplified with the results of a decision-support exercise designed for simulation and prediction of the dynamic inter-relationships between socio-economic development and environmental quality for the "Wen, Pi, Du" county in Sichuan province, southwestern China.
基金Supported by the 973 Project in China under Grant No. 61383National Natural Science Foundation of China under Grant No. 11004011+1 种基金Defence Industrial Technology Development Program under Grant No. B1520110002Open Project of State Key Labo-ratory of Explosion Science and Technology (Beijing Institute of Technology,No. KFJJ11-2M)
文摘Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contribution to mixture explosives.The work starts from the force-field derivation.We get ab initio based pair potentials across the interface,and then use them to study the interface structural and mechanical properties.A series of large scale molecular dynamics simulations are performed.The structure evolution,energy variation and elastic/plastic transformation of interface and polycrystal systems are calculated.The desensitizing mechanism of graphite to HMX is discussed.
基金Under the auspices of National Natural Science Foundation of China(No.40871063)
文摘Port-city system is a complex and integral system, and it can be simulated by system dynamic method, which is used to be employed to solve nonlinear problems. Based on the causality of the every element in the port-city system, the authors analyzed the feedback relation and logical relation among the system variables and system structure. A system-dynamic flow chart and correlation equations were put forward with VENSIM software, the quantitative relation was described, and the model was debugged. The development trend of the main influence factors in port-city system was simulated. By changing the influence degree of each related factor. It is found the parameters values of variables in the model, we studied that： 1） Foreign trade throughput of port play an important role in the development of export-oriented economy. 2） The development of primary industry and secondary industry affects most of the water transportation demand. With the constant increase of tertiary industry proportion in the industrial structure, the demand of national economy for water transportation decreases gradually. 3） Water transportation presents a kind of oversupply development situation, so port construction should properly slow down. 4） With the development of ports, its direct and indirect contribution to urban economy has been continuously increasing, but contribution rate will be continuously decreasing.
基金Supported by Scientific Research Fund of Hunan Provincial Education Department under Grant No.07B075Interactive Project Fund of Xiangtan University under Grant No.061ND09Initial Scientific Research Fund of Xiangtan University
文摘We perform langevin dynamics simulation for envelope solitons in an FPU-β lattice,with the nearestneighborinteraction and quartic anharmonicity.We get the motion equations of our discrete system by adding noiseand damping to the set of deterministic motion equations.We define'half-time'as the time when the amplitude of theenvelope soliton decreases by half due to damping.And then the mass,center and half-time of the perturbed envelopesoliton are numerically simulated,beginning with the discrete envelope soliton at rest.Results show successfully hownoise affects behavior of the envelope soliton.
文摘The common properties of risk in long tunnel fires are high temperature, extreme difficulty of evacuation, rescue urgency and obstacle to rescue operation. Therefore, a complete ventilation design is an indispensable safety measure. Hsueh-Shan Tunnel is the longest in Taiwan, the fifth longest in the world. On May 7, 2012, a serious tunnel fire caused two deaths and numerous victims suffered from smoke inhalation injury. Apart from this, there was smoking entering the cross-passages and shafts which were important for evacuation. In this research, the current ventilation system in Hsueh-Shan Tunnel was simulated with FDS （fire dynamics simulator） software, and the statistics of smoke, visibility and temperature profile were analyzed. The results of this research showed that, with the current ventilation system, the time was shorter and the distance was longer for the smoke spreading windward than in other models. Furthermore, the visibility of windward victims was more affected and the temperature above the fire source was higher than those in other systems. When the wind speed in tunnel is within 2.0-4.0 m/s, the condition for turning off the ventilation fan within 250 m upwind from the fire source can be prominently reduced to 50 m upwind from the fire source. This not only could avoid plume disturbance but also could be maintained. If victims＇ evacuation should be given the highest priority, it is recommended to straightly activate the maximum power of the fan.
基金Supported by the National Research Foundation of South Africa
文摘In principle, non-Hermitian quantum equations of motion can be formulated using as a starting point either the Heisenberg＇s or the Schroedinger＇s picture of quantum dynamics. Here it is shown in both cases how to map the algebra of commutators, defining the time evolution in terms of a non-Hermitian Hamiltonian, onto a non-Hamiltonian algebra with a Hermitian Hamiltonian. The logic behind such a derivation is reversible, so that any Hermitian Hamiltonian can be used in the formulation of non-Hermitian dynamics through a suitable algebra of generalized （non-Hamiltonian） commutators. These results provide a general structure （a template） for non-Hermitian equations of motion to be used in the computer simulation of open quantum systems dynamics.
