基于Freeman分解的植被参数反演新方法

基于极化Freeman分解的极化协方差矩阵参数,极化干涉SAR互协方差矩阵可简化建模为植被高度、消光系数和地面干涉相位的函数。基于此,该文建立了以极化干涉SAR互协方差矩阵估算值与互协方差矩阵观测值之差为目标函数、以3个植被参数为未知量的优化模型,提出了基于Freeman分解的植被参数反演新方法。该方法避免了三阶段植被参数估计方法所面临的体相关系数确定问题,提供了一种独立于三阶段植被参数估计的新思路。仿真结果验证了新方法的有效性。     

一种天线阵列定位法及其仿真研究

为了克服CDMA移动台(MS)定位估计中面临的远近效应问题,该文提出了一种在服务基站(BS)附近布置一种天线阵列,采用TSOA/AOA混合定位技术对MS进行定位估计的方法,分析了采用不同定位法的GDOP分布, 并给出了相应的TSOA/AOA混合定位算法。不同条件下的仿真结果表明,只要AOA测量值达到一定精度,采用这种方法就能对MS进行准确定位。     

激光告警技术中视场误差分析

论述了激光告警设备角分辨力的误差源,认为接收电路动态范围不够,光学视场光阑不合适,接收光敏面相对光阑太大,窗口安装误差及在光纤耦合体制下光纤耦合方式不完善都是引起误差的主要原因,文中分析介绍了减少这些误差的方法。     

部件分解法／高频混合法在复杂目标散射近场预估中的应用

本文结合物理光学（PO）法、几何绕射理论（GTD）、弹跳射线法（SBR）等高频方法和部件分解法,研究了电大尺寸复杂目标的近场散射特性。     

一种改进的物理光学迭代法

该文使用线积分形式的Kirchhoff公式替代F.Obelleiro(1995)提出的物理光学迭代(IPO)法中的经典Kirchhoff公式,提出了一种改进的IPO法。数值计算结果表明,改进的IPO法和FObelleiro(1995)的IPO法比较,对三面角反射器、飞机座舱等大口面凹型腔体的电磁散射特性分析,在数值精度相当的情况下,计算速度明显提高。     

混合高斯噪声背景下基于多目标优化的节点选择方法

为解决非高斯噪声背景下,基于贝叶斯Fisher信息矩阵和基于互信息的节点选择不一致的问题,该文提出一种基于多目标优化的节点选择方法。推导出节点噪声为混合高斯分布时的贝叶斯Fisher信息矩阵和互信息,将节点个数、选择的节点对应的Fisher信息矩阵和互信息共同作为优化的目标函数。提出利用基于分解的多目标优化方法寻找Pareto最优解,并采用与理想解相似的偏好排序技术(TOPSIS)从所有Pareto最优解中选择最终的节点选择方案。仿真实验结果表明,基于多目标优化的节点选择方法选择的节点具有更优更稳健的定位精度。

     

YOLSO: You Only Look Small Object

Small object detection is challenging and far from satisfactory. Most general object detectors suffer from two critical issues with small objects: (1) Feature extractor based on classification network cannot express the characteristics of small objects reasonably due to insufficient appearance information of targets and a large amount of background interference around them. (2) The detector requires a much higher location accuracy for small objects than for general objects. This paper proposes an effective and efficient small object detector YOLSO to address the above problems. For feature representation, we analyze the drawbacks in previous backbones and present a Half-Space Shortcut(HSSC) module to build a background-aware backbone. Furthermore, a coarse-to-fine Feature Pyramid Enhancement(FPE) module is introduced for layer-wise aggregation at a granular level to enhance the semantic discriminability. For loss function, we propose an exponential L1 loss to promote the convergence of regression, and a focal IOU loss to focus on prime samples with high classification confidence and high IOU. Both of them significantly improves the location accuracy of small objects. The proposed YOLSO sets state-of-the-art results on two typical small object datasets, MOCOD and VeDAI, at a speed of over 200 FPS. In the meantime, it also outperforms the baseline YOLOv3 by a wide margin on the common COCO dataset.     

Coverage and Energy Modeling of HetNet Under Base Station On‐Off Model

Small cell networks, as an important evolution path for next‐generation cellular networks, have drawn much attention. Different from the traditional base stations (BSs) always‐on model, we proposed a BSs on‐off model, where a new, simple expression for the probabilities of active BSs in a heterogeneous network is derived. This model is more suitable for application in practical networks. Based on this, we develop an analytical framework for the performance evaluation of small cell networks, adopting stochastic geometry theory. We derive the system coverage probability; average energy efficiency (AEE) and average uplink power consumption (AUPC) for different association strategies; maximum biased received power (MaBRP); and minimum association distance (MiAD). It is analytically shown that MaBRP is beneficial for coverage but will have some loss in energy saving. On the contrary, MiAD is not advocated from the point of coverage but is more energy efficient. The simulation results show that the use of range expansion in MaBRP helps to save energy but that this is not so in MiAD. Furthermore, we can achieve an optimal AEE by establishing an appropriate density of small cells.     

腔体结构电磁散射分析新方法

本文提出一种综合了复射线和几何光学射线法优点的腔体结构电磁散射分析方法－高斯射线管方法。讨论了单位平面波的高斯射线管模拟，以及高斯射线管在曲界面上的反射问题。给出了用高斯射线管计算腔体结构散射的典型算例。     

江西省中小河流岸坡整治技术集成及典型模式研究

本文在分析江西省中小河流存在的问题、治理现状等基础上,研究中小河流治理岸坡整治技术集成,并结合工程实例研究科学适用的解决方案和岸坡生态整治的典型模式,为江西省中小河流岸坡生态治理提供建议.