Inverse speed is a reversible maneuver.It is a characteristic of underwater vehicle at low speed.Maneuverability in the vertical plane at a speed lower than inverse speed is different from one at higher speed.In the p...Inverse speed is a reversible maneuver.It is a characteristic of underwater vehicle at low speed.Maneuverability in the vertical plane at a speed lower than inverse speed is different from one at higher speed.In the process of underwater working for observation,AUV's cruise speed is always low.Therefore,the research on inverse speed is important to AUV's maneuverability.The mechanism of inverse speed was analyzed,and then the steady pitching equation was derived.The parameter expression of track angle in vertical plane was deduced.Furthermore,the formula to calculate the inverse speed was obtained.The typical inverse speed phenomenon of the flat body and the revolving body was analyzed.Then the conclusion depicts that,for a particular AUV with flat body,its inverse speed is lower than that of revolving body.After all the calculation and the analysis,a series of special experiments of inverse speed were carried out in the simulation program,in the tank and in the sea trial.展开更多
A novel network control method based on trophaUaxis mechanism is applied to the formation flight problem for multiple un- manned aerial vehicles （UAVs）. Firstly, the multiple UAVs formation flight system based on tr...A novel network control method based on trophaUaxis mechanism is applied to the formation flight problem for multiple un- manned aerial vehicles （UAVs）. Firstly, the multiple UAVs formation flight system based on trophallaxis network control is given. Then, the model of leader-follower formation flight with a virtual leader based on trophallaxis network control is pre- sented, and the influence of time delays on the network performance is analyzed. A particle swarm optimization （PSO）-based formation controller is proposed for solving the leader-follower formation flight system. The proposed method is applied to five UAVs for achieving a ＇V＇ formation, and a series of experimental results show its feasibility and validity. The proposed control algorithm is also a promising control strategy for formation flight of multiple unmanned underwater vehicles （UUVs）, unmanned ground vehicles （UGVs）, missiles and satellites.展开更多
Though the bumper of a vehicle plays a major role in protecting the vehicle body against damage in low speed impacts, many bumpers, particularly in large vehicles, are too stiff for pedestrian protection. In designing...Though the bumper of a vehicle plays a major role in protecting the vehicle body against damage in low speed impacts, many bumpers, particularly in large vehicles, are too stiff for pedestrian protection. In designing a bumper for an automobile, pedestrian protection is as important as bumper energy absorption in low speed collisions. To prevent lower extremity injuries in car-pedestrian collisions, it is important to determine the loadings that car front structures impart on the lower extremities and the mechanisms by which injury is caused by these loadings. The present work was focused on gaining more insight into the injury mechanisms leading to both ligament damage and bone fracture during bumper-pedestrian collisions. The European Enhanced Vehicle-safety Committee （EEVC） legform impactor model was introduced and validated against EEVCAVG17 criteria. The collision mechanism between a bumper and this legform impactor was investigated numerically using LS-DYNA software. To identify the effect of the bumper beam material on leg injuries, four analyses were performed on bumpers that had the same assembly but were made from different materials.展开更多
基金Projects(51179035,51279221) supported by the National Natural Science Foundation of ChinaProject(E201121) supported by Science Foundation of Heilongjiang Province,China
文摘Inverse speed is a reversible maneuver.It is a characteristic of underwater vehicle at low speed.Maneuverability in the vertical plane at a speed lower than inverse speed is different from one at higher speed.In the process of underwater working for observation,AUV's cruise speed is always low.Therefore,the research on inverse speed is important to AUV's maneuverability.The mechanism of inverse speed was analyzed,and then the steady pitching equation was derived.The parameter expression of track angle in vertical plane was deduced.Furthermore,the formula to calculate the inverse speed was obtained.The typical inverse speed phenomenon of the flat body and the revolving body was analyzed.Then the conclusion depicts that,for a particular AUV with flat body,its inverse speed is lower than that of revolving body.After all the calculation and the analysis,a series of special experiments of inverse speed were carried out in the simulation program,in the tank and in the sea trial.
基金supported by the National Natural Science Foundation of China(Grant Nos.61273054,60975072 and 60604009)the National Basic Research Program of China("973"Project)(Grant No.2013CB035503)+1 种基金the Program for New Century Excellent Talents in University of China(Grant No.NCET-10-0021)the Aeronautical Foundation of China(Grant No.20115151019)
文摘A novel network control method based on trophaUaxis mechanism is applied to the formation flight problem for multiple un- manned aerial vehicles （UAVs）. Firstly, the multiple UAVs formation flight system based on trophallaxis network control is given. Then, the model of leader-follower formation flight with a virtual leader based on trophallaxis network control is pre- sented, and the influence of time delays on the network performance is analyzed. A particle swarm optimization （PSO）-based formation controller is proposed for solving the leader-follower formation flight system. The proposed method is applied to five UAVs for achieving a ＇V＇ formation, and a series of experimental results show its feasibility and validity. The proposed control algorithm is also a promising control strategy for formation flight of multiple unmanned underwater vehicles （UUVs）, unmanned ground vehicles （UGVs）, missiles and satellites.
文摘Though the bumper of a vehicle plays a major role in protecting the vehicle body against damage in low speed impacts, many bumpers, particularly in large vehicles, are too stiff for pedestrian protection. In designing a bumper for an automobile, pedestrian protection is as important as bumper energy absorption in low speed collisions. To prevent lower extremity injuries in car-pedestrian collisions, it is important to determine the loadings that car front structures impart on the lower extremities and the mechanisms by which injury is caused by these loadings. The present work was focused on gaining more insight into the injury mechanisms leading to both ligament damage and bone fracture during bumper-pedestrian collisions. The European Enhanced Vehicle-safety Committee （EEVC） legform impactor model was introduced and validated against EEVCAVG17 criteria. The collision mechanism between a bumper and this legform impactor was investigated numerically using LS-DYNA software. To identify the effect of the bumper beam material on leg injuries, four analyses were performed on bumpers that had the same assembly but were made from different materials.
