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1. chinaXiv:201904.00084 [pdf]

A simulation study of GNSS-R polarimetric scattering from the bare soil surface based on the AIEM model

吴学睿
Subjects: Geosciences >> Geochemistry

In the past two decades, Global Navigation Satellite System-Reflectometry (GNSS-R) has emerged as a new remote sensing technique for soil moisture monitoring. Some experiments showed that the antenna of V polarization is more favorable to receive the reflected signals, and the interference pattern technique (IPT) was used for soil moisture and other geophysical parameters retrieval. Meanwhile, the lower satellite elevation angles are most impacted by the multipath. However, electromagnetic theoretical properties are not clear for GNSS-R soil moisture retrieval. In this paper, the Advanced Integral Equation Model (AIEM) is employed using the wave synthesis technique to simulate different polarimetric scattering at the specular directions. Results show when the incidence angles are larger than 70º, scattering at RR polarization (The transmitted signal is Right Hand Circular Polarization (RHCP), while the received one is also RHCP) is larger than that one at LR polarization (The transmitted signal is RHCP, while the received one is Left Hand Circular Polarization (LHCP)), while scattering at LR polarization is larger than that at RR polarization for the other incident angles(1º~70º). There is an apparent dip for VV and VR scattering due to the Brewster angle, which will result in the notch in the final receiving power and this phenomenon can be used for soil moisture retrieval or vegetation corrections. The volumetric soil moisture (vms) effects on their scattering are also presented. The larger soil moisture will result in lower scattering at RR polarization, and this is very different from the scattering of the other polarizations. It is interesting to note that the surface correlation function only affects the amplitudes of the scattering coefficients at much less level, but it has no effects on the angular trends of RR and LR polarizations.

submitted time 2019-04-10 Hits681Downloads60 Comment 0

2. chinaXiv:201904.00085 [pdf]

全极化GNSS-R陆面参数延迟多普勒图模型

吴学睿; 金双根
Subjects: Geosciences >> Geodestics

目前,针对GNSS-R的研究多从观测角度出发,对其散射机理研究相对较少。本文针对GNSS-R(GNSS-Reflectometry)反射信号陆面参数的延迟多普勒图理论模型展开研究,对于陆面参数(裸土、植被)的双站散射特性的计算采用修改后的随机粗糙面散射模型和零阶/一阶辐射传输方程模型。通过该模型模拟分析了裸土、植被参数变化时,相应的延迟多普勒图的变化。同时为利用极化信息进行相应地物参数的后向反演,模型中增加全极化计算功能。全极化GNSS+R陆面参数延迟多普勒图理论模型的研究有助于星载数据的解释、地表实验设计、数据仿真和后向反演算法的开发。

submitted time 2019-04-10 Hits1742Downloads396 Comment 0

3. chinaXiv:201904.00081 [pdf]

接圆回归

何沧平
Subjects: Mathematics >> Computational Mathematics.

本文提出一个名为接圆回归的点击率预测新方法,尝试替代常用的因子分解机(FM)。接圆回归用超平面拼接出一个封闭凸多面体,圈出正样本,有直观的几何解释, 能从任意初始值一次收敛到全局最优解。 拟合出来的曲面Lipschitz连续,变化平缓。在人工设计的星环集、双堆集、双月集上,接圆回归的分类准确性、解释性、平滑性全面超过FM。在同量级参数量、计算量 的条件下,接圆回归在Avazu集和Criteo集上的AUC超过FM。

submitted time 2019-04-10 Hits842Downloads83 Comment 0

4. chinaXiv:201904.00082 [pdf]

母亲守门行为与母亲教养投入、母子依恋的关系及发展性差异

邹盛奇; 伍新春; 黄彬彬; 刘畅
Subjects: Psychology >> Developmental Psychology

基于家庭系统理论与依恋理论提出了一个母亲守门行为通过母亲教养投入预测母子依恋的间接效应模型,同时考察了这一模型在青少年发展阶段上的差异。采用问卷法对597个核心家庭的母亲和青少年进行调查,结果发现:(1)总体上,母亲开门行为对母亲教养投入和母子依恋均具有正向预测作用,母亲教养投入对母子依恋具有正向预测作用,间接效应模型成立;母亲关门行为对母亲教养投入的预测作用不显著,对母子依恋具有负向预测作用,间接效应模型不成立;(2)从发展阶段来看,母亲开门行为的间接效应模型在三个发展阶段均成立,且间接效应大小无差异;母亲关门行为的间接效应模型只在早期和后期成立,且两发展阶段的作用性质相反,早期为正向预测作用,后期为负向预测作用。结果补充和扩展了母亲守门行为的作用效果研究,并且强调了青少年发展阶段在其中的作用,对家庭教育实践具有一定的指导意义。

submitted time 2019-04-10 Hits912Downloads83 Comment 0

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