The present work investigates the influence of ignition delay on the diesel engine performance. A theoretical model is used via a program written by MATLAB, to compute the ignition delay in (ms) for a diesel engine at...The present work investigates the influence of ignition delay on the diesel engine performance. A theoretical model is used via a program written by MATLAB, to compute the ignition delay in (ms) for a diesel engine at identical operation conditions. The ignition delay in the diesel engines using different reference diesel fuels with different cetane numbers of 40 and 50 was investigated. Effect of the operating conditions such as the engine compression ratios, intake pressures and temperatures on the ignition delay, was investigated. Influences of engine speed changes on ignition delay at low, moderate and high conditions were represented. Comparisons between obtained results for the two types of the used fuels were also represented. The results show that the ignition delay decreases with increasing the engine speed, the engine compression ratio, cetane number, intake pressure and temperature. The compression ratio causes remarkable reduction in ignition delay.展开更多
Teleoperation rendezvous and docking can be used as a backup for autonomous rendezvous and docking（RVD） for an unmanned spacecraft when the autonomous system is failure or for guiding the chaser docking with an unco...Teleoperation rendezvous and docking can be used as a backup for autonomous rendezvous and docking（RVD） for an unmanned spacecraft when the autonomous system is failure or for guiding the chaser docking with an uncooperative target.The theoretical model for analyzing the handling qualities in teleoperation RVD process is established based on the previous studies conducted by National Aeronautics and Space Administration（NASA）.The predictive factor is introduced to describe the pilot＇s predictive ability in the teleoperation tasks with time delay,which interrelates with the skills of a pilot and the predictive assist approach used in the tasks such as the predictive display method.Based on the semi-physical simulation system in our laboratory,900 experiments at two levels of time delay are carried out by 18 volunteers for validating the established model.The experimental results demonstrate the correctness of the theoretical model and indicate that a skilled pilot has a predictive ability of approximately 0.9 in teleoperation RVD tasks.The theoretical analysis shows that the handling qualities are greatly affected by the time delay and the predictive factor,and it is impossible to achieve a teleoperation RVD task for the skilled pilot when the time delay is larger than 9.0 s.展开更多
This paper gives an equivalent condition for the observability of Boolean control networks（BCNs） with time-variant delays in states under a mild assumption by using the graph-theoretic method under the framework of ...This paper gives an equivalent condition for the observability of Boolean control networks（BCNs） with time-variant delays in states under a mild assumption by using the graph-theoretic method under the framework of the semi-tensor product of matrices. First, the BCN under consideration is split into a finite number of subsystems with no time delays. Second, the observability of the BCN is verified by testing the observability of the so-called observability constructed path（a special subsystem without time delays） based on graph theory. These results extend the recent related results on the observability of BCNs. Examples are shown to illustrate the effectiveness of the results.展开更多
文摘The present work investigates the influence of ignition delay on the diesel engine performance. A theoretical model is used via a program written by MATLAB, to compute the ignition delay in (ms) for a diesel engine at identical operation conditions. The ignition delay in the diesel engines using different reference diesel fuels with different cetane numbers of 40 and 50 was investigated. Effect of the operating conditions such as the engine compression ratios, intake pressures and temperatures on the ignition delay, was investigated. Influences of engine speed changes on ignition delay at low, moderate and high conditions were represented. Comparisons between obtained results for the two types of the used fuels were also represented. The results show that the ignition delay decreases with increasing the engine speed, the engine compression ratio, cetane number, intake pressure and temperature. The compression ratio causes remarkable reduction in ignition delay.
文摘Teleoperation rendezvous and docking can be used as a backup for autonomous rendezvous and docking（RVD） for an unmanned spacecraft when the autonomous system is failure or for guiding the chaser docking with an uncooperative target.The theoretical model for analyzing the handling qualities in teleoperation RVD process is established based on the previous studies conducted by National Aeronautics and Space Administration（NASA）.The predictive factor is introduced to describe the pilot＇s predictive ability in the teleoperation tasks with time delay,which interrelates with the skills of a pilot and the predictive assist approach used in the tasks such as the predictive display method.Based on the semi-physical simulation system in our laboratory,900 experiments at two levels of time delay are carried out by 18 volunteers for validating the established model.The experimental results demonstrate the correctness of the theoretical model and indicate that a skilled pilot has a predictive ability of approximately 0.9 in teleoperation RVD tasks.The theoretical analysis shows that the handling qualities are greatly affected by the time delay and the predictive factor,and it is impossible to achieve a teleoperation RVD task for the skilled pilot when the time delay is larger than 9.0 s.
基金supported by the National Natural Science Foundation of China under Grant Nos.61603109and 51209051the Natural Science Foundation of Heilongjiang Province of China under Grant No.LC2016023+1 种基金the Fundamental Research Funds for the Central Universities under Grant Nos.HEUCFM170406 and HEUCFM170112the State Key Laboratory of Ocean Engineering(Shanghai Jiao Tong University)under Grant No.1415
文摘This paper gives an equivalent condition for the observability of Boolean control networks（BCNs） with time-variant delays in states under a mild assumption by using the graph-theoretic method under the framework of the semi-tensor product of matrices. First, the BCN under consideration is split into a finite number of subsystems with no time delays. Second, the observability of the BCN is verified by testing the observability of the so-called observability constructed path（a special subsystem without time delays） based on graph theory. These results extend the recent related results on the observability of BCNs. Examples are shown to illustrate the effectiveness of the results.
