Most cited articles
2011, 43(4):28-31,36.
DOI: 10.11918/j.issn.0367-6234.2011.04.006
Abstract:
To study the connection method between reinforced bars of the precast concrete(PC) structure,81 plug-in filling hole for lap-joint of steel bar sample tests were made,and the main factors,such as reinforced bar diameter,concrete strength and anchorage length etc.were considered during the tests.The test results indicated that the ultimate failure state of all the anchoring specimens were the external reinforced bar yielding or broken up by pulling,and the abnormal anchorage was not destroyed.When the basic anchoring length was reduced by 10% or even 20%,specimens still showed enough safety.Based on this,the basic anchoring length of plug-in filling hole for lap-joint of steel bar can be given as 0.8 la.
To study the connection method between reinforced bars of the precast concrete(PC) structure,81 plug-in filling hole for lap-joint of steel bar sample tests were made,and the main factors,such as reinforced bar diameter,concrete strength and anchorage length etc.were considered during the tests.The test results indicated that the ultimate failure state of all the anchoring specimens were the external reinforced bar yielding or broken up by pulling,and the abnormal anchorage was not destroyed.When the basic anchoring length was reduced by 10% or even 20%,specimens still showed enough safety.Based on this,the basic anchoring length of plug-in filling hole for lap-joint of steel bar can be given as 0.8 la.
2017, 49(3):1-14.
DOI: 10.11918/j.issn.0367-6234.2017.03.001
Abstract:
It is well known that unmanned aerial vehicle (UAV) is more and more widely applied in military and civil areas. In order to play the better role of UAV, it is needed to utilize multi UAVs cooperative formation to accomplish cooperative reconnaissance, combat, defense and spraying pesticides and other tasks. The multi UAVs cooperative formation control technology mainly contains the following key techniques: data fusion technology, sensing technology, task allocation technology, path planning technology, formation control technology, communication network technology and virtual/physical verification platform technology. Firstly, summarize the research and development of key technologies worldwide. Then, the classification for multi UAVs formation control methods is mainly investigated, and the problems about formation design and adjustment, formation reconfiguration are summarized. Finally, the challenges and future development for multi UAV cooperative formation are prospected. Research shows: at present, the theory of multi UAV formation flight has acquired fruitful results, while the real cooperative formation flight test can only be implemented in the simple communication environment. The real time performance for task allocation and path planning is not high. The robustness of control methods to cope with the unexpected situation is low. The cooperative sensing ability for multi UAV with multi sensor is insufficient. The simulation of the entity is lacked. Breaking through the above key technologies, carrying out the cooperative formation flight of multi UAV in complex sensing constraints and complex communication environment, putting forward more effective control method and carrying out the UAV physical formation flying test so that the UAV can finish the task better may be the future research directions.
It is well known that unmanned aerial vehicle (UAV) is more and more widely applied in military and civil areas. In order to play the better role of UAV, it is needed to utilize multi UAVs cooperative formation to accomplish cooperative reconnaissance, combat, defense and spraying pesticides and other tasks. The multi UAVs cooperative formation control technology mainly contains the following key techniques: data fusion technology, sensing technology, task allocation technology, path planning technology, formation control technology, communication network technology and virtual/physical verification platform technology. Firstly, summarize the research and development of key technologies worldwide. Then, the classification for multi UAVs formation control methods is mainly investigated, and the problems about formation design and adjustment, formation reconfiguration are summarized. Finally, the challenges and future development for multi UAV cooperative formation are prospected. Research shows: at present, the theory of multi UAV formation flight has acquired fruitful results, while the real cooperative formation flight test can only be implemented in the simple communication environment. The real time performance for task allocation and path planning is not high. The robustness of control methods to cope with the unexpected situation is low. The cooperative sensing ability for multi UAV with multi sensor is insufficient. The simulation of the entity is lacked. Breaking through the above key technologies, carrying out the cooperative formation flight of multi UAV in complex sensing constraints and complex communication environment, putting forward more effective control method and carrying out the UAV physical formation flying test so that the UAV can finish the task better may be the future research directions.
2013, 45(6):83-89.
DOI: 10.11918/j.issn.0367-6234.2013.06.015
Abstract:
To comprehensively evaluate the seismic performance of precast concrete shear wall with vertical reinforcements grouted in holes and spliced indirectly in horizontal connections, two fabricated and a cast-in-place concrete shear wall with full scale specimens were tested under low cyclic loading. The test results show that the concrete interior shear wall specimens (JN) is basically the same as the cast-in-place specimen (XJ) in failure modes, but the concrete exterior shear wall specimen wall (JW) is different with the XJ. The hysteresis curve of the specimen is full, the trend of the skeleton curve is basically the same and the capacity of the energy dissipation is close. The ultimate displacement angle of each specimen is 1/56-1/49 and the displacement ductility factor are 4. The initial stiffness of JW, JN are lower than the XJ, and the force behavior is improved in exterior wall specimens (JW) with the setting position of horizontal connections moved up.
To comprehensively evaluate the seismic performance of precast concrete shear wall with vertical reinforcements grouted in holes and spliced indirectly in horizontal connections, two fabricated and a cast-in-place concrete shear wall with full scale specimens were tested under low cyclic loading. The test results show that the concrete interior shear wall specimens (JN) is basically the same as the cast-in-place specimen (XJ) in failure modes, but the concrete exterior shear wall specimen wall (JW) is different with the XJ. The hysteresis curve of the specimen is full, the trend of the skeleton curve is basically the same and the capacity of the energy dissipation is close. The ultimate displacement angle of each specimen is 1/56-1/49 and the displacement ductility factor are 4. The initial stiffness of JW, JN are lower than the XJ, and the force behavior is improved in exterior wall specimens (JW) with the setting position of horizontal connections moved up.
