作为中国观察员我七月初出席了第十一届国际心理学注意和行为(Attention and performance)会议。会议在美国西海岸北部城市Eugene市的Oregon大学举行。到会的七十多位心理学家来自世界各地,他们中的三十多位作了大会发言,为期一周的会...作为中国观察员我七月初出席了第十一届国际心理学注意和行为(Attention and performance)会议。会议在美国西海岸北部城市Eugene市的Oregon大学举行。到会的七十多位心理学家来自世界各地,他们中的三十多位作了大会发言,为期一周的会议内容很广泛,不仅包括注意而且涉及行动控制,语言,大脑两半球的联系等。会上会下心理学界的同行们围绕着注意到行为这一认知过程的重要阶段的许多问题,都广泛深入地进行了学术交流。我注意到了一些很有希望的心理学家并没有作大会发言(象A.Treisman,S.Sterberg)。会议主席团的一个成员告诉我,因为发言的机会有限,他们规定把一比例的发言机会留给年轻人及第一次参加会议的人。然而每一个发言都是经推荐,初稿审批。展开更多
A new kind of flexible pneumatic wall-climbing robot,named WALKMAN-I,was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA),a flexible pneumatic spherical joint and six suction cups. It h...A new kind of flexible pneumatic wall-climbing robot,named WALKMAN-I,was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA),a flexible pneumatic spherical joint and six suction cups. It has many characteristics of low-cost,lightweight,simple structure and good flexibility. Its operating principle was introduced. Then three basic locomotion modes,which are linear motion,curvilinear motion and crossing the orthogonal planes,were presented. The safety conditions of WALKMAN-I were discussed and built. Finally,the control system was designed and experiments were carried out. Experimental results show that WALKMAN-I is able to climb on the vertical wall surface along a straight line or a curved path,and has the ability of crossing orthogonal planes and obstacles. The maximum rotation angle reaches 90°,the maximum velocity reaches 5 mm/s,and the rotation angle and the moving velocity of WALKMAN-I can be easily controlled.展开更多
A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environment...A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.展开更多
The hybrid tracked vehicles(HTV)usually adopt series hybrid powertrain with extra steering mechanism,which has relatively low transmission efficiency and reduces the flexibility of structural arrangement.To overcome t...The hybrid tracked vehicles(HTV)usually adopt series hybrid powertrain with extra steering mechanism,which has relatively low transmission efficiency and reduces the flexibility of structural arrangement.To overcome the disadvantages,a new kind of single-mode powertrain has been proposed.The power-split hybrid powertrain is composed of three planetary gear(PG)sets connected to one engine,left and right track outputs,and three motors.The proposed powertrain can realize steering while going forward by controlling the output torque on each side without extra steering mechanism or steering shaft.Due to the diversity of the connection way between components and planetary gear sets,a rapid configuration design approach is proposed for the design selection of HTV.The automated dynamic modelling method can show the one-to-one correspondence with the selected feasible groups by establishing two characteristic matrices,which is more simple than other researches.The analytically-based method is proposed to classify all possible connection designs into several groups to decrease the searching scope with improved design efficiency.Finally,the optimal control strategy is used to find the design with optimal fuel economy under typical condition of HTV.The case study is implemented by the proposed design approach which demonstrates better design performances compared with the existing series-hybrid HTV.展开更多
In recent years,unmanned aerial vehicles(UAVs)have acquired an increasing interest due to their wide range of applications in military,scientific,and civilian fields.One of the quadcopter limitations is its lack of fu...In recent years,unmanned aerial vehicles(UAVs)have acquired an increasing interest due to their wide range of applications in military,scientific,and civilian fields.One of the quadcopter limitations is its lack of full actuation property which limits its mobility and trajectory tracking capabilities.In this work,an overactuated quadcopter design and control,which allows independent tilting of the rotors around their arm axis,is presented.Quadcopter with this added tilting mechanism makes it possible to overcome the aforementioned mobility limitation by achieving full authority on torque and force vectoring.The tilting property increases the control inputs to 8(the 4 propeller rotation speed plus the 4 rotor tilting angles)which gives a full control on the quadcopter states.Extensive mathematical model for the tilt rotor quadcopter is derived based on the Newton-Euler method.Furthermore,the feedback linearization method is used to linearize the model and a mixed sensitivity H∞optimal controller is then designed and synthesized to achieve the required performance and stability.The controlled system is simulated to assure the validity of the proposed controller and the quadcopter design.The controller is tested for its effectiveness in rejecting disturbances,attenuating sensor noise,and coping with the model uncertainties.Moreover,a complicated trajectory is examined in which the tilt rotor quadcopter has been successfully followed.The test results show the supremacy of the overactuated quadcopter over the traditional one.展开更多
The utilization of biomimicry of bacterial foraging strategy was considered to develop an adaptive control strategy for mobile robot, and a bacterial foraging approach was proposed for robot path planning. In the prop...The utilization of biomimicry of bacterial foraging strategy was considered to develop an adaptive control strategy for mobile robot, and a bacterial foraging approach was proposed for robot path planning. In the proposed model, robot that mimics the behavior of bacteria is able to determine an optimal collision-free path between a start and a target point in the environment surrounded by obstacles. In the simulation, two test scenarios of static environment with different number obstacles were adopted to evaluate the performance of the proposed method. Simulation results show that the robot which reflects the bacterial foraging behavior can adapt to complex environments in the planned trajectories with both satisfactory accuracy and stability.展开更多
文摘作为中国观察员我七月初出席了第十一届国际心理学注意和行为(Attention and performance)会议。会议在美国西海岸北部城市Eugene市的Oregon大学举行。到会的七十多位心理学家来自世界各地,他们中的三十多位作了大会发言,为期一周的会议内容很广泛,不仅包括注意而且涉及行动控制,语言,大脑两半球的联系等。会上会下心理学界的同行们围绕着注意到行为这一认知过程的重要阶段的许多问题,都广泛深入地进行了学术交流。我注意到了一些很有希望的心理学家并没有作大会发言(象A.Treisman,S.Sterberg)。会议主席团的一个成员告诉我,因为发言的机会有限,他们规定把一比例的发言机会留给年轻人及第一次参加会议的人。然而每一个发言都是经推荐,初稿审批。
基金Project (50575206) supported by the National Natural Science Foundation of ChinaProject (BX102716) supported by Xinmiao Program of Zhejiang Province, China
文摘A new kind of flexible pneumatic wall-climbing robot,named WALKMAN-I,was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA),a flexible pneumatic spherical joint and six suction cups. It has many characteristics of low-cost,lightweight,simple structure and good flexibility. Its operating principle was introduced. Then three basic locomotion modes,which are linear motion,curvilinear motion and crossing the orthogonal planes,were presented. The safety conditions of WALKMAN-I were discussed and built. Finally,the control system was designed and experiments were carried out. Experimental results show that WALKMAN-I is able to climb on the vertical wall surface along a straight line or a curved path,and has the ability of crossing orthogonal planes and obstacles. The maximum rotation angle reaches 90°,the maximum velocity reaches 5 mm/s,and the rotation angle and the moving velocity of WALKMAN-I can be easily controlled.
基金Project(20030533011)supported by the National Research Foundation for the Doctoral Program of Higher Education of China
文摘A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.
基金Project(CIT&TCD20190304)supported by the Beijing Great Scholars Program,China。
文摘The hybrid tracked vehicles(HTV)usually adopt series hybrid powertrain with extra steering mechanism,which has relatively low transmission efficiency and reduces the flexibility of structural arrangement.To overcome the disadvantages,a new kind of single-mode powertrain has been proposed.The power-split hybrid powertrain is composed of three planetary gear(PG)sets connected to one engine,left and right track outputs,and three motors.The proposed powertrain can realize steering while going forward by controlling the output torque on each side without extra steering mechanism or steering shaft.Due to the diversity of the connection way between components and planetary gear sets,a rapid configuration design approach is proposed for the design selection of HTV.The automated dynamic modelling method can show the one-to-one correspondence with the selected feasible groups by establishing two characteristic matrices,which is more simple than other researches.The analytically-based method is proposed to classify all possible connection designs into several groups to decrease the searching scope with improved design efficiency.Finally,the optimal control strategy is used to find the design with optimal fuel economy under typical condition of HTV.The case study is implemented by the proposed design approach which demonstrates better design performances compared with the existing series-hybrid HTV.
文摘In recent years,unmanned aerial vehicles(UAVs)have acquired an increasing interest due to their wide range of applications in military,scientific,and civilian fields.One of the quadcopter limitations is its lack of full actuation property which limits its mobility and trajectory tracking capabilities.In this work,an overactuated quadcopter design and control,which allows independent tilting of the rotors around their arm axis,is presented.Quadcopter with this added tilting mechanism makes it possible to overcome the aforementioned mobility limitation by achieving full authority on torque and force vectoring.The tilting property increases the control inputs to 8(the 4 propeller rotation speed plus the 4 rotor tilting angles)which gives a full control on the quadcopter states.Extensive mathematical model for the tilt rotor quadcopter is derived based on the Newton-Euler method.Furthermore,the feedback linearization method is used to linearize the model and a mixed sensitivity H∞optimal controller is then designed and synthesized to achieve the required performance and stability.The controlled system is simulated to assure the validity of the proposed controller and the quadcopter design.The controller is tested for its effectiveness in rejecting disturbances,attenuating sensor noise,and coping with the model uncertainties.Moreover,a complicated trajectory is examined in which the tilt rotor quadcopter has been successfully followed.The test results show the supremacy of the overactuated quadcopter over the traditional one.
基金Project(61173032)supported by the National Natural Science Foundation of ChinaProject(20090406)supported by the Tianjin Scientific and Technological Development Fund of Higher Education of China
文摘The utilization of biomimicry of bacterial foraging strategy was considered to develop an adaptive control strategy for mobile robot, and a bacterial foraging approach was proposed for robot path planning. In the proposed model, robot that mimics the behavior of bacteria is able to determine an optimal collision-free path between a start and a target point in the environment surrounded by obstacles. In the simulation, two test scenarios of static environment with different number obstacles were adopted to evaluate the performance of the proposed method. Simulation results show that the robot which reflects the bacterial foraging behavior can adapt to complex environments in the planned trajectories with both satisfactory accuracy and stability.
