Overbuilding, i.e. capping or decking, of roads assigned for the transportation of dangerous goods in major cities is being considered more often in many countries including Sweden. This type of facility introduces a ...Overbuilding, i.e. capping or decking, of roads assigned for the transportation of dangerous goods in major cities is being considered more often in many countries including Sweden. This type of facility introduces a number of risks and challenges related to rare events, such as dangerous goods accidents in tunnels, with a potential to cause substantial damage, e.g. collapse of buildings on the over site development. Many argue that the major problem associated with risk evaluation of such risks is the lack of commonly agreed acceptance criteria and regulations. Approaching the problem from a scientific perspective suggests that the root cause of this problem has not been adequately identified. However, there are strong indications that it is because the nature of the risk is not adequately addressed in risk analysis. In this study, we have structured the problem and propose ways of making progress in the evaluation of risk exposure and risk control. It is concluded that several challenges are inherent in the risk management of decking over routes for the transport of dangerous goods, and that these must be addressed in order to be able to control the risk. One of the complicating factors is that it is practically and economically impossible to construct the overbuilding so that it can withstand the maximum permissible explosion load. The main conclusions of this study are that overbuilding of dangerous goods routes has the potential to lead to catastrophic events, that the transport of dangerous goods in the future is associated with considerable intrinsic uncertainties, and that the possibility of supervising and controlling the transport of goods is limited once the route is in use.展开更多
Variable-air-volume (VAV) air-conditioning system is a multi-variable system and has multi coupling control loops. While all of the control loops are working together, they interfere and influence each other. A multiv...Variable-air-volume (VAV) air-conditioning system is a multi-variable system and has multi coupling control loops. While all of the control loops are working together, they interfere and influence each other. A multivariable decoupling PID controller is designed for VAV air-conditioning system. Diagonal matrix decoupling method is employed to eliminate the coupling between the loop of supply air temperature and that of thermal-space air temperature. The PID controller parameters are optimized by means of an improved genetic algorithm in floating point representations to obtain better performance. The population in the improved genetic algorithm mutates before crossover, which is helpful for the convergence. Additionally the micro mutation algorithm is proposed and applied to improve the convergence during the later evolution. To search the best parameters, the optimized parameters ranges should be amplified 10 times the initial ideal parameters. The simulation and experiment results show that the decoupling control system is effective and feasible. The method can overcome the strong coupling feature of the system and has shorter governing time and less over-shoot than non-optimization PID control.展开更多
文摘Overbuilding, i.e. capping or decking, of roads assigned for the transportation of dangerous goods in major cities is being considered more often in many countries including Sweden. This type of facility introduces a number of risks and challenges related to rare events, such as dangerous goods accidents in tunnels, with a potential to cause substantial damage, e.g. collapse of buildings on the over site development. Many argue that the major problem associated with risk evaluation of such risks is the lack of commonly agreed acceptance criteria and regulations. Approaching the problem from a scientific perspective suggests that the root cause of this problem has not been adequately identified. However, there are strong indications that it is because the nature of the risk is not adequately addressed in risk analysis. In this study, we have structured the problem and propose ways of making progress in the evaluation of risk exposure and risk control. It is concluded that several challenges are inherent in the risk management of decking over routes for the transport of dangerous goods, and that these must be addressed in order to be able to control the risk. One of the complicating factors is that it is practically and economically impossible to construct the overbuilding so that it can withstand the maximum permissible explosion load. The main conclusions of this study are that overbuilding of dangerous goods routes has the potential to lead to catastrophic events, that the transport of dangerous goods in the future is associated with considerable intrinsic uncertainties, and that the possibility of supervising and controlling the transport of goods is limited once the route is in use.
基金Supported by Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education of China
文摘Variable-air-volume (VAV) air-conditioning system is a multi-variable system and has multi coupling control loops. While all of the control loops are working together, they interfere and influence each other. A multivariable decoupling PID controller is designed for VAV air-conditioning system. Diagonal matrix decoupling method is employed to eliminate the coupling between the loop of supply air temperature and that of thermal-space air temperature. The PID controller parameters are optimized by means of an improved genetic algorithm in floating point representations to obtain better performance. The population in the improved genetic algorithm mutates before crossover, which is helpful for the convergence. Additionally the micro mutation algorithm is proposed and applied to improve the convergence during the later evolution. To search the best parameters, the optimized parameters ranges should be amplified 10 times the initial ideal parameters. The simulation and experiment results show that the decoupling control system is effective and feasible. The method can overcome the strong coupling feature of the system and has shorter governing time and less over-shoot than non-optimization PID control.
