为满足复杂干扰场景和阵列误差因素影响下雷达微弱目标信号精确测向需求,提出一种基于均匀线阵构建虚拟波束,替代阵列接收信号进行四阶累积量(fourth-order cumulant,FOC)波达方向(direction of arrival,DOA)估计的算法。该算法包括两...为满足复杂干扰场景和阵列误差因素影响下雷达微弱目标信号精确测向需求,提出一种基于均匀线阵构建虚拟波束,替代阵列接收信号进行四阶累积量(fourth-order cumulant,FOC)波达方向(direction of arrival,DOA)估计的算法。该算法包括两个关键步骤:一是利用阵列接收信号特征分解的方法,对信号主信息分量进行提取,并以构建的虚拟波束为输入,计算FOC矩阵;二是针对主分量虚拟波束波瓣外的起伏,利用高斯窗修正波束方向图的方法,进一步提升空间谱函数的估计精度。仿真结果表明,该方法在存在阵列误差的非理想因素下,对复杂电磁干扰场景下的目标信号DOA估计精度较现有FOC方法提高150%以上,尤其对于场内同时存在多个非等功率源信号时,所提方法对低信噪比目标DOA估计精度提升效果优势明显,对复杂干扰环境下DOA估计精度更高、适应性更强。展开更多
This paper firstly introduces the structure and working principle of DSP-based parallel system, parallel accelerating board and SHARC DSP chip. Then it pays attention to investigating the system’s programming charact...This paper firstly introduces the structure and working principle of DSP-based parallel system, parallel accelerating board and SHARC DSP chip. Then it pays attention to investigating the system’s programming characteristics, especially the mode of communication, discussing how to design parallel algorithms and presenting a domain-decomposition-based complete multi-grid parallel algorithm with virtual boundary forecast (VBF) to solve a lot of large-scale and complicated heat problems. In the end, Mandelbrot Set and a non-linear heat transfer equation of ceramic/metal composite material are taken as examples to illustrate the implementation of the proposed algorithm. The results showed that the solutions are highly efficient and have linear speedup.展开更多
Experiments were conducted to evaluate the performance of vertical blowing fans(VBF)for frost protection in a vineyard on a steep slope near Napa Valley in Northern California,USA,and a tea plantation located on undul...Experiments were conducted to evaluate the performance of vertical blowing fans(VBF)for frost protection in a vineyard on a steep slope near Napa Valley in Northern California,USA,and a tea plantation located on undulating terrain in Zhenjiang,China.Minimum temperature comparisons from within the grape vineyard on nights with and without VBF operation with control station minimum temperatures exhibited no temperature benefit.Profile measurements from the test in China indicated that there was an increase in temperature when the VBF was first started,but that benefit was lost over time.No clear benefit from using the VBF was observed.Observation of frost deposition and thermal imagery also showed no benefit except for within about 5 m of the VBF.Based on this work,the effectiveness of the VBF for frost protection was not validated.展开更多
In this paper, an optimum tactic of multi-grid parallel algorithmwith virtual boundary forecast method is disscussed, and a two-stage implementationis presented. The numerical results of solving a non-linear heat tran...In this paper, an optimum tactic of multi-grid parallel algorithmwith virtual boundary forecast method is disscussed, and a two-stage implementationis presented. The numerical results of solving a non-linear heat transfer equationshow that the optimum implementation is much better than the non-optimum one.展开更多
The potential of muon colliders opens up new possibilities for the exploration of new physics beyond the Standard Model.It is worthwhile to investigate whether muon colliders are suitable for studying gluonic quartic ...The potential of muon colliders opens up new possibilities for the exploration of new physics beyond the Standard Model.It is worthwhile to investigate whether muon colliders are suitable for studying gluonic quartic gauge couplings(gQGCs),which can be contributed by dimension-8 operators in the framework of the Standard Model effective field theory,and are intensively studied recently.In this paper,we study the sensitivity of the processμ^(+)μ^(-)→jjν■to gQGCs.Our results indicate that the muon colliders with c.m.energies larger than 4 TeV can be more sensitive to gQGCs than the Large Hadron Collider.展开更多
文摘为满足复杂干扰场景和阵列误差因素影响下雷达微弱目标信号精确测向需求,提出一种基于均匀线阵构建虚拟波束,替代阵列接收信号进行四阶累积量(fourth-order cumulant,FOC)波达方向(direction of arrival,DOA)估计的算法。该算法包括两个关键步骤:一是利用阵列接收信号特征分解的方法,对信号主信息分量进行提取,并以构建的虚拟波束为输入,计算FOC矩阵;二是针对主分量虚拟波束波瓣外的起伏,利用高斯窗修正波束方向图的方法,进一步提升空间谱函数的估计精度。仿真结果表明,该方法在存在阵列误差的非理想因素下,对复杂电磁干扰场景下的目标信号DOA估计精度较现有FOC方法提高150%以上,尤其对于场内同时存在多个非等功率源信号时,所提方法对低信噪比目标DOA估计精度提升效果优势明显,对复杂干扰环境下DOA估计精度更高、适应性更强。
基金Project (No. 60173046) supported by the National Natural ScienceFoundation of China
文摘This paper firstly introduces the structure and working principle of DSP-based parallel system, parallel accelerating board and SHARC DSP chip. Then it pays attention to investigating the system’s programming characteristics, especially the mode of communication, discussing how to design parallel algorithms and presenting a domain-decomposition-based complete multi-grid parallel algorithm with virtual boundary forecast (VBF) to solve a lot of large-scale and complicated heat problems. In the end, Mandelbrot Set and a non-linear heat transfer equation of ceramic/metal composite material are taken as examples to illustrate the implementation of the proposed algorithm. The results showed that the solutions are highly efficient and have linear speedup.
基金This work was funded by National High Technology Research and Development Program of China(2012AA10A508)Special Fund of Non-profit Scientific Research for Agriculture(201303012)Priority Academic Program Development of Jiangsu Higher Education Institutions(2014-37).
文摘Experiments were conducted to evaluate the performance of vertical blowing fans(VBF)for frost protection in a vineyard on a steep slope near Napa Valley in Northern California,USA,and a tea plantation located on undulating terrain in Zhenjiang,China.Minimum temperature comparisons from within the grape vineyard on nights with and without VBF operation with control station minimum temperatures exhibited no temperature benefit.Profile measurements from the test in China indicated that there was an increase in temperature when the VBF was first started,but that benefit was lost over time.No clear benefit from using the VBF was observed.Observation of frost deposition and thermal imagery also showed no benefit except for within about 5 m of the VBF.Based on this work,the effectiveness of the VBF for frost protection was not validated.
文摘In this paper, an optimum tactic of multi-grid parallel algorithmwith virtual boundary forecast method is disscussed, and a two-stage implementationis presented. The numerical results of solving a non-linear heat transfer equationshow that the optimum implementation is much better than the non-optimum one.
基金supported in part by the National Natural Science Foundation of China under Grants Nos.11905093 and 12147214the Natural Science Foundation of the Liaoning Scientific Committee No.LJKZ0978.
文摘The potential of muon colliders opens up new possibilities for the exploration of new physics beyond the Standard Model.It is worthwhile to investigate whether muon colliders are suitable for studying gluonic quartic gauge couplings(gQGCs),which can be contributed by dimension-8 operators in the framework of the Standard Model effective field theory,and are intensively studied recently.In this paper,we study the sensitivity of the processμ^(+)μ^(-)→jjν■to gQGCs.Our results indicate that the muon colliders with c.m.energies larger than 4 TeV can be more sensitive to gQGCs than the Large Hadron Collider.
