单脉冲雷达未分辨目标波达方向(direction of arrival,DOA)估计是跟踪雷达抗干扰领域的一个难点问题,现有方法通常假定干信比已知,限制了其在实际雷达系统中的应用。针对密集假信号存在下的单脉冲雷达未分辨目标DOA估计问题,提出了一种...单脉冲雷达未分辨目标波达方向(direction of arrival,DOA)估计是跟踪雷达抗干扰领域的一个难点问题,现有方法通常假定干信比已知,限制了其在实际雷达系统中的应用。针对密集假信号存在下的单脉冲雷达未分辨目标DOA估计问题,提出了一种无需干信比先验信息的未分辨目标DOA估计方法。首先通过对密集假信号聚类估计出诱饵DOA,然后推导了以诱饵DOA为参数的目标DOA估计解析表达式。仿真结果表明,所提算法能在密集假信号干扰下准确估计干扰和目标DOA。展开更多
A new approach to solving the observation of enhanced neutron production in high-energy heavy ion induced reactions in thick targets is presented. Two different reaction mechanisms in these interactions are considered...A new approach to solving the observation of enhanced neutron production in high-energy heavy ion induced reactions in thick targets is presented. Two different reaction mechanisms in these interactions are considered: 1) Limited fragmentation of the projectile, called SPALLATION;2) Complete nuclear fragmentation of the projectile fragment into individual relativistic hadrons only, referred to as “BURST”. The abundance of this second path increases with the charge and energy of the projectile and may be responsible for enhanced neutron production observed with radiochemical methods in 44 GeV 12C and 72 GeV 40Ar irradiations. Interactions of 72 GeV 22Ne in nuclear emulsions show that SPALLATION and BURST have strongly different interaction signatures, and also that the rate of BURSTS increases from (26 ± 3)% of all interactions in the 1st generation to (78 ± 6)% in the 2nd generation. Further experimental signatures of BURSTS will be described;however, no model based on physics concepts can be presented. This effect may have practical consequences for neutron safety considerations in the construction of advanced heavy ion accelerators.展开更多
根据有限集统计方法,推导得到了可适用于不可分辨目标跟踪问题的势概率假设密度(cardinalized probability hypothesis density,CPHD)滤波器。类似传统的点目标CPHD滤波器,该不可分辨目标CPHD滤波器不仅可以递推地传递多目标状态集合的...根据有限集统计方法,推导得到了可适用于不可分辨目标跟踪问题的势概率假设密度(cardinalized probability hypothesis density,CPHD)滤波器。类似传统的点目标CPHD滤波器,该不可分辨目标CPHD滤波器不仅可以递推地传递多目标状态集合的一阶统计矩,还可以传递多目标个数(即势)的概率分布。蒙特卡罗仿真实验表明,相比Mahler提出的不可分辨目标PHD滤波器,所提出的不可分辨目标CPHD滤波器具有更加精确和稳定的多目标个数和状态估计,但它的计算量要大于不可分辨目标PHD滤波器。展开更多
An enhanced neutron production and an enhanced nuclear destruction due to secondary fragments have been observed in very thick targets irradiated with high energy ions. This enhancement is beyond theoretical calculati...An enhanced neutron production and an enhanced nuclear destruction due to secondary fragments have been observed in very thick targets irradiated with high energy ions. This enhancement is beyond theoretical calculations and it is an unresolved problem. It is observed only when primary ion interactions exceed an energy threshold (ECM/u ≈ 150 MeV). Investigations using nuclear emulsions for very high-energy nuclear reactions suggest that two distinctly different classes of relativistic projectile-like fragments are emitted in primary interactions: a “cool” channel with a temperature of (T(p)cool ≈ 10 MeV), and a “hot” channel with (T(p)hot ≈ 40 MeV. This second reaction class may induce the above mentioned enhanced reactions of secondary fragments, thus being responsible for unresolved problems. This assumption should be studied in further experiments. Nuclear interactions of secondary particles in thick targets are of interest, in particular in view of radiation protection needs for high energy and high intensity heavy ion accelerators. Many basic ideas of this paper go back to the late Professor E. Schopper (Frankfurt).展开更多
文摘单脉冲雷达未分辨目标波达方向(direction of arrival,DOA)估计是跟踪雷达抗干扰领域的一个难点问题,现有方法通常假定干信比已知,限制了其在实际雷达系统中的应用。针对密集假信号存在下的单脉冲雷达未分辨目标DOA估计问题,提出了一种无需干信比先验信息的未分辨目标DOA估计方法。首先通过对密集假信号聚类估计出诱饵DOA,然后推导了以诱饵DOA为参数的目标DOA估计解析表达式。仿真结果表明,所提算法能在密集假信号干扰下准确估计干扰和目标DOA。
文摘A new approach to solving the observation of enhanced neutron production in high-energy heavy ion induced reactions in thick targets is presented. Two different reaction mechanisms in these interactions are considered: 1) Limited fragmentation of the projectile, called SPALLATION;2) Complete nuclear fragmentation of the projectile fragment into individual relativistic hadrons only, referred to as “BURST”. The abundance of this second path increases with the charge and energy of the projectile and may be responsible for enhanced neutron production observed with radiochemical methods in 44 GeV 12C and 72 GeV 40Ar irradiations. Interactions of 72 GeV 22Ne in nuclear emulsions show that SPALLATION and BURST have strongly different interaction signatures, and also that the rate of BURSTS increases from (26 ± 3)% of all interactions in the 1st generation to (78 ± 6)% in the 2nd generation. Further experimental signatures of BURSTS will be described;however, no model based on physics concepts can be presented. This effect may have practical consequences for neutron safety considerations in the construction of advanced heavy ion accelerators.
文摘根据有限集统计方法,推导得到了可适用于不可分辨目标跟踪问题的势概率假设密度(cardinalized probability hypothesis density,CPHD)滤波器。类似传统的点目标CPHD滤波器,该不可分辨目标CPHD滤波器不仅可以递推地传递多目标状态集合的一阶统计矩,还可以传递多目标个数(即势)的概率分布。蒙特卡罗仿真实验表明,相比Mahler提出的不可分辨目标PHD滤波器,所提出的不可分辨目标CPHD滤波器具有更加精确和稳定的多目标个数和状态估计,但它的计算量要大于不可分辨目标PHD滤波器。
文摘An enhanced neutron production and an enhanced nuclear destruction due to secondary fragments have been observed in very thick targets irradiated with high energy ions. This enhancement is beyond theoretical calculations and it is an unresolved problem. It is observed only when primary ion interactions exceed an energy threshold (ECM/u ≈ 150 MeV). Investigations using nuclear emulsions for very high-energy nuclear reactions suggest that two distinctly different classes of relativistic projectile-like fragments are emitted in primary interactions: a “cool” channel with a temperature of (T(p)cool ≈ 10 MeV), and a “hot” channel with (T(p)hot ≈ 40 MeV. This second reaction class may induce the above mentioned enhanced reactions of secondary fragments, thus being responsible for unresolved problems. This assumption should be studied in further experiments. Nuclear interactions of secondary particles in thick targets are of interest, in particular in view of radiation protection needs for high energy and high intensity heavy ion accelerators. Many basic ideas of this paper go back to the late Professor E. Schopper (Frankfurt).
