排序方式: 共有10条查询结果,搜索用时 15 毫秒
1
1.
2.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(6):2759-2769
In this study, predictions of the E-CHAIM ionospheric model are compared with measurements by the incoherent scatter radars RISR at Resolute Bay, Canada, in the northern polar cap. Reasonable coverage was available for all seasons except winter for which no conclusions were drawn. It is shown that ratios of the model-to measured electron densities are close to unity in the central part of the F layer, around its peak. This is particularly evident for summer daytime. Distributions of the ratios are wider for other seasons indicating larger number of cases when the model underestimates or overestimates. E-CHAIM underestimates the electron density at ionospheric topside and bottomside by ~ 10–20 %. At the bottomside, the underestimations are strongest in summer and equinoctial nighttime. At the topside, the underestimations are strongest in autumn nighttime. Model overestimations are noticeable in the middle part of the F layer during dawn hours in autumn. Overall, the model tends to not predict highest-observed peak electron densities and the largest-observed heights of the peak. 相似文献
3.
对2D雷达与3D雷达的航迹关联问题进行了研究,提出了两种通过升维来达到航迹关联的算法,解决了2D雷达与3D雷达同地、异地配置的关联问题。通过典型环境下的仿真,体现了算法较好的关联性能和较强的鲁棒性。 相似文献
4.
5.
星载雷达由于其探测范围广、距离远、全天候等优点,在预警防御系统中占有十分重要的地位。然而,由于观测平台的高速运动以及摄动干扰、传感器观测非线性等问题,使得星载雷达目标高精度跟踪带来严峻挑战。针对星载雷达非线性状态估计问题,采用一种基于变分贝叶斯的非线性滤波方法,该方法通过将非线性状态估计问题转化为优化问题,通过迭代优化获得了闭环解析解。此外,针对坐标变换中俯仰角量测缺失问题,提出了一种基于先验目标高度的俯仰角估计方法。通过数值仿真,验证了所提方法较传统非线性滤波方法,如扩展卡尔曼滤波、不敏卡尔曼滤波、转换量测卡尔曼滤波,具有更好的估计精度。 相似文献
6.
7.
Elías M. Lau Hiroyuki Iimura Scott E. Palo Susan K. Avery James P. Avery Chunmei Kang Nikolai A. Makarov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
A new meteor radar system was installed at the Amundsen–Scott station South Pole in 2001 to further the understanding of the dynamics of the Antarctic region. The antenna array consists of four yagis pointed along the 0°, 90°, 180°, and 270° meridians and five folded crossed dipoles arranged in a cross configuration and operating as an interferometer to provide position measurements for the detected radio meteors. The four yagis are time division multiplexed and used for both transmitting and receiving while the five folded crossed dipoles are only used for reception. The current arrangement of data acquisition (DAQ) systems at the South Pole allows the collection of meteors in a configuration similar to the previous meteor radar system that operated at the South Pole in the mid 1990s while also using an interferometer to accurately determine the meteor positions in the sky, which enables the determination of the vertical structure of the observed waves. This has been accomplished through the use of two DAQ and post-processing systems: COBRA (Colorado Obninsk radar) connected to the yagis and MEDAC (meteor echo detection and collection) connected to the folded crossed dipoles. With two separate DAQ systems operating in parallel we have the ability to directly compare the results and understand the inherent variability in the derived scientific results based on different system architectures and processing assumptions. The impact of operating a system without an interferometer on the amplitudes and phases of the observed wave components is considered. We find that the lack of altitude resolution of the COBRA DAQ system leads to an underestimation of the amplitude of the s = 1 component of the semidiurnal tide of ∼20% during the summer months. 相似文献
8.
饱和时序下防空相控阵雷达动态优先级调度算法 总被引:1,自引:0,他引:1
针对防空相控阵雷达负载饱和情况下的时间分配问题,提出一种基于目标威胁密度和截止期的雷达任务动态优先级调度算法。根据目标信息建立非线性目标威胁度模型并设计动态优先级表,然后,利用目标威胁度、任务驻留时间和截止期共同确定任务的综合优先级。在此基础上,提出执行威胁率(TRE)的评估指标,以反映调度算法对重要任务的执行情况。仿真结果表明,在饱和时序下,相比于传统的截止期最早最优先算法,改进算法的搜索性能提高了43%,执行威胁率提高了52%。 相似文献
9.
性能退化与间歇故障是机载雷达健康状态的重要反映。针对传统机载雷达健康评估方法缺乏整机级的监测指标、未能综合考虑性能退化和间歇故障,传统BIT电路难以监测间歇故障等工程难题,提出了基于通道校准链路,综合运用通道校准仿真技术、正态云、HMM建立起健康状态评估流程。首先,对通道误差与间歇故障进行分析,得到4类校正系数,建立误差与间歇故障注入仿真流程;然后,基于正态云,利用校正系数的样本方差来表征雷达系统的健康状态,提出统一健康模型,并给出HMM拓扑结构与参数设计方法;最后,建立起基于数据驱动的评估流程并开展应用研究。仿真实验验证了误差和间歇故障仿真流程的可行性、健康状态评估方法的有效性,可获得大于95%的评估准确率;应用案例表明所提方法可行,能解决工程上机载雷达健康状态评估的问题。 相似文献
10.
舰载雷达系统包括多种型号的雷达,在舰艇施放舷外有源诱饵对抗ARM时,不能简单地将其视为单一辐射源目标。通过分析舰载雷达辐射源工作特性,建立了舷外有源诱偏条件下ARM对舰载雷达的攻击模型。仿真结果表明,ARM散落点在舰载雷达周围分布较为密集,可以对舰载雷达系统构成了较大的威胁。 相似文献
1