In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it i...In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it is not worth consuming scarce resources of sensors in computing the trajectory of each single target. Hence, in this paper, the problem is modeled as tracking a geographical continuous region covered by all targets. A tracking algorithm is proposed to estimate the region covered by the target group in each sampling period. Based on the locations of sensors and the azimuthal angle of arrival （AOA） information, the estimated region covering all the group members is obtained. Algorithm analysis provides the fundamental limits to the accuracy of localizing a target group. Simulation results show that the proposed algorithm is superior to the existing hull algorithm due to the reduction in estimation error, which is between 10% and 40% of the hull algorithm, with a similar density of sensors. And when the density of sensors increases, the localization accuracy of the proposed algorithm improves dramatically.展开更多
The ratio of the number of emitted pions from the target side to that from the projectile side at target rapidity within the reaction plane is investigated for the study of the pion dynamics with an isospin-dependent ...The ratio of the number of emitted pions from the target side to that from the projectile side at target rapidity within the reaction plane is investigated for the study of the pion dynamics with an isospin-dependent quantum molecular dynamic model. The results show that high-energy pions are emitted preferentially towards the target side and, therefore, they are freezed out at the early stage of the collision. By contrast, low-energy pions are emitted predominantly in the opposite direction, which means that they are emitted in a later stage. This argument is based on the shadowing effect caused by the interaction of pions with the spectator matter in peripheral collisions at target or projectile rapidities. This phenomenon disappears in the central collision or at midrapidity due to the weaker shadowing effect. The calculated ratios are also compared with the experimental data.展开更多
基金Project supported by the State Key Program of the National Natural Science Foundation of China(Grant No.60835001)the National Natural Science Foundation of China(Grant No.61104068)the Natural Science Foundation of Jiangsu Province China(Grant No.BK2010200)
文摘In this paper, we explore the technology of tracking a group of targets with correlated motions in a wireless sensor network. Since a group of targets moves collectively and is restricted within a limited region, it is not worth consuming scarce resources of sensors in computing the trajectory of each single target. Hence, in this paper, the problem is modeled as tracking a geographical continuous region covered by all targets. A tracking algorithm is proposed to estimate the region covered by the target group in each sampling period. Based on the locations of sensors and the azimuthal angle of arrival （AOA） information, the estimated region covering all the group members is obtained. Algorithm analysis provides the fundamental limits to the accuracy of localizing a target group. Simulation results show that the proposed algorithm is superior to the existing hull algorithm due to the reduction in estimation error, which is between 10% and 40% of the hull algorithm, with a similar density of sensors. And when the density of sensors increases, the localization accuracy of the proposed algorithm improves dramatically.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11421505 and 11220101005the National Basic Research Program of China under Grant No 2014CB845401
文摘The ratio of the number of emitted pions from the target side to that from the projectile side at target rapidity within the reaction plane is investigated for the study of the pion dynamics with an isospin-dependent quantum molecular dynamic model. The results show that high-energy pions are emitted preferentially towards the target side and, therefore, they are freezed out at the early stage of the collision. By contrast, low-energy pions are emitted predominantly in the opposite direction, which means that they are emitted in a later stage. This argument is based on the shadowing effect caused by the interaction of pions with the spectator matter in peripheral collisions at target or projectile rapidities. This phenomenon disappears in the central collision or at midrapidity due to the weaker shadowing effect. The calculated ratios are also compared with the experimental data.
