On the Radiative Properties of Ice Clouds:Light Scattering, Remote Sensing,and Radiation Parameterization

Presented is a review of the radiative properties of ice clouds from three perspectives： light scattering simulations, remote sensing applications, and broadband radiation parameterizations appropriate for numerical models. On the subject of light scattering simulations, several classical computational approaches are reviewed, including the conventional geometric-optics method and its improved forms, the finite-difference time domain technique, the pseudo-spectral time domain technique, the discrete dipole approximation method, and the T-matrix method, with specific applications to the computation of the singlescattering properties of individual ice crystals. The strengths and weaknesses associated with each approach are discussed.With reference to remote sensing, operational retrieval algorithms are reviewed for retrieving cloud optical depth and effective particle size based on solar or thermal infrared（IR） bands. To illustrate the performance of the current solar- and IR-based retrievals, two case studies are presented based on spaceborne observations. The need for a more realistic ice cloud optical model to obtain spectrally consistent retrievals is demonstrated. Furthermore, to complement ice cloud property studies based on passive radiometric measurements, the advantage of incorporating lidar and/or polarimetric measurements is discussed.The performance of ice cloud models based on the use of different ice habits to represent ice particles is illustrated by comparing model results with satellite observations. A summary is provided of a number of parameterization schemes for ice cloud radiative properties that were developed for application to broadband radiative transfer submodels within general circulation models（GCMs）. The availability of the single-scattering properties of complex ice habits has led to more accurate radiation parameterizations. In conclusion, the importance of using nonspherical ice particle models in GCM simulations for climate studies is proven.

The microwave scattering characteristics of sea ice in the Bohai Sea

Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these studies have been barely carried in the Bohai Sea. The sea-ice microwave scattering mechanism was first developed for the thin sea ice with slight roughness in the Bohai Sea in the winter of 2012, and included the backscattering coefficients which were measured on the different conditions of three bands（L, C and X）, two polarizations（HH and VV）, and incident angles of 20° to 60°, using a ground-based scatterometer and the synchronous physical parameters of the sea-ice temperature, density, thickness, salinity, and so on. The theoretical model of the sea-ice electromagnetic scattering is obtained based on these physical parameters. The research regarding the sea-ice microwave scattering mechanism is carried out through two means, which includes the comparison between the field microwave scattering data and the simulation results of the theoretical model, as well as the feature analysis of the four components of the sea-ice electromagnetic scattering. It is revealed that the sea-ice microwave scattering data and the theoretical simulation results vary in the same trend with the incident angles. Also, there is a visible variant in the sensitivity of every component to the different bands.For example, the C and X bands are sensitive to the top surface, the X band is sensitive to the scatterers, and the L and C bands are sensitive to the bottom surface, and so on. It is suggested that the features of the sea-ice surfaces and scatterers can be retrieved by the further research in the future. This experiment can provide an experimental and theoretical foundation for research regarding the sea-ice microwave scattering characteristics in the Bohai Sea.

MATERIAL ELECTROMAGNETIC PARAMETERS EXTRACTION USING SVM METHOD

The method extracting the electromagnetic parameters from scattering coefficients was studied in this paper. The Support Vector Machine (SVM) method is used to solve the inverse problem of parameters extraction. The mapping relationship is set up by calculating a large number of S pa-rameters from the samples with different permittivity by using transmission line theory. The simulated data set is used as training data set for SVM. After the training, the SVM is used to predict the permittivity of material from the scattering coefficients.

卷云在红外波段的散射特性

文中用T矩阵(T matrix)、Lorenz Mie等效球和几何光学(GOM)相结合的方法计算了六角冰晶尺度在1 10000μm范围内、波长在红外2.5～13μm范围内的散射特性。依据局地实际测量的三十种卷云粒子尺度分布,得到有效尺度从15～160μm卷云粒子的平均散射特性,并把这些单次散射特性参数化成卷云有效直径的多项式函数。

散乱数据点的邻近关系及参数化

逆向工程中要解决的重要问题之一是对散乱测量数据进行参数化处理。本文提出了建立散乱数据点间的邻近关系及基于这种关系的数据点凸组合映射参数化方法。实例表明 ,本文所介绍的方法简单可靠 。

参数化的多次散射激光雷达方程和它的反演理论 Ⅰ:方程

本文提出了一个参数化的多次散射激光雷达方程,该方程基于本文引出的四个因子,即几何消光因子、消光分布因子、前向散射因子和后向散射因子.前两个因子表征多次散射成分对大气消光系数分布、激光的发散角和接收视场角以及接收孔径的依赖关系,后两个因子表征多次散射成分对散射相函数的依赖关系.这个参数化多次散射雷达方程在241个数值试验中得以检验,这些试验包含很宽的大气条件和雷达几何参数,包括14个大气散射相函数,均匀和不均匀的大气消光系数分布,0.5至1之间变化的一次散射反照率,地基和空间站激光雷达两种情形.数值试验表明,在小于4的光学厚度内参数化的解和Monte-Carlo解之间的标准偏差小于27％,而本模式的计算时间比Monte-Carlo方法偏小4个数量级左右.本模式不仅适合于研究多次散射对激光回波信号和激光大气遥感的效应,而且对于考虑多次散射的激光大气探测而言,是一个合适的应用模式.

散乱点云数据的曲率估算及应用

提出一种直接在散乱数据点云上计算曲面的局部微分性质,包括平均曲率、高斯曲率和主曲率。首先,计算各点的邻近点集,选取合适的局部基础曲面,把邻近点集投影到相应的局部基础曲面。然后,在以局部基础曲面内投影点的参数化代替空间邻近点集的参数化的基础上,用二次参数曲面逼近空间邻近点集,从而计算出各点的法矢,再对不协调的法矢方向进行调整。最后,利用曲率公式计算出各点的曲率。试验表明这种方法可以较好反映曲面的特征。运用该曲率算法对海量数据进行了简化。

Tissue scattering parameter estimation through scattering phase function measurements by goniometer

An automated optical system is built up to perform goniometric measurement of scattering phase function. Measurements of typical samples including monodisperse polystyrene micro-spheres solution, and mutlidis- perse polystyrene micro-spheres solution are carried out in a dark room. The possibility of estimating the average particle size of phantom through analyzing its scattering phase function is demonstrated.

中能区p-α散射的唯象振幅

在整个中能区范围内就P－α散射的唯象振幅问题进行了讨论，拟会了从200MeV－1730MeV的实验数据，对两种典型的唯象振幅进行了分析对比。这些振幅对利用中能质子研究原子核的α粒子结构问题是必要的输入量。

Crosstalk Study in a FBG-MOC-Based OXC Using Scattering Parameters

Crosstalk in FBG-MOC-based OXCs is simulated using scattering parameters and compared with that in FBG-OC-based OXCs. The former is able to enhance the output power without significant degradation in signal-to-crosstalk ratio compared with the latter.

Design, Fabrication, and Modeling of CMOS-Compatible Double Photodiode

A double photodiode (PD) constructed by p+/N-well junction and N-well/p-sub junction was designed and fabricated in a UMC 0.18-μm CMOS process. Based on the device structure and mechanism of double PD, a novel small-signal equivalent circuit model considering the carrier transit effect and the parasitic RC time constant was presented. By this model with complete electronic components, the double PD can be incorporated in a commercial circuit simulator. The component values were extracted by fitting the measured S-parameters using simulated annealing algorithm, and a good agreement between the measurement and the simulation results was achieved. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

三维属性散射中心系数的多项式模型

为了解决多角度SAR数据三维属性散射中心提取中出现的散射系数函数形式未知、数据量大的问题,提出了一种对散射系数进行参数化建模的方法。这种建模方法在忽略雷达频率对散射系数的影响的前提下,首先根据散射系数幅度分段,然后在段内利用二维多项式进行建模。通过仿真实验验证,该方法简单易行,通过参数化模型恢复的图像,和原始图像有很高的相似度。不过,这种方法不能应用于延展型属性散射中心,需要在下一步的工作中继续进行研究。

基于散射参数的船用电力电缆模型验证(英文)

Careful analysis of transients in shipboard power systems is important to achieve long life times of the components in future all-electric ships.In order to accomplish results with high accuracy,it is recommended to validate cable models as they have significant influence on the amplitude and frequency spectrum of voltage transients.The authors propose comparison of model and measurement using scattering parameters.They can be easily obtained from measurement and simulation and deliver broadband information about the accuracy of the model.The measurement can be performed using a vector network analyzer.The process to extract scattering parameters from simulation models is explained in detail.Three different simulation models of a 5 kV XLPE power cable have been validated.The chosen approach delivers an efficient tool to quickly estimate the quality of a model.

Probe method to measure the electromagnetic field in a plasma by Poynting vector conversion

In this paper,a high-precision electromagnetic measurement system suitable for a hightemperature and high-speed plasma is built to provide a platform for scientific research on the interaction mechanism of the electromagnetic fields and a plasma.This paper presents a method to measure the electromagnetic field inside a plasma by using a probe and Poynting vector conversion,which is a new and completely different method from the traditional method of measuring the electromagnetic field inside plasma.In addition,for this system and method,this work designs a microstrip antenna probe that can suppress multipath effects.This method is confirmed to be valid and usable after closed-loop verification by the CST software.

Measurement and Characterization of Microwave Interaction between Integrated Distributed Feedback Laser Diode and Electro-Absorption Modulator

Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modulation.In integrated EML,the microwave interaction between the distributed feedback laser diode(DFB-LD)and the electro-absorption modulator(EAM)has a nonnegligible influence on the modulation performance,especially at the high-frequency region.In this paper,integrated EML was investigated as a three-port network with two electrical inputs and a single optical output,where the scattering matrix of the integrated device was theoretically deduced and experimentally measured.Based on the theoretical model and the measured data,the microwave equivalent circuit model of the integrated device was established,from which the microwave interaction between DFB-LD and EAM was successfully extracted.The results reveal that the microwave interaction within integrated EML contains both the electrical isolation and optical coupling.The electrical isolation is bidirectional while the optical coupling is directional,which aggravates the microwave interaction in the direction from DFB-LD to EAM.

Experiment of Frequency Range Dependent TE10 to TE20 Mode Converter

Typical metallic waveguide mode converters convert electromagnetic waves from one mode to another mode for some frequency ranges. However, most electromagnetic waves outside of the specified frequency range are reflected. We report a design for a mode converter which passes the TE10 mode at a low frequency range and efficiently converts the TE10 mode to the TE20 mode at a high frequency range. To gradually shift the mode profile from TE10 to TE20, dielectric rods are placed in a sequence along the waveguide starting near the sidewall and moving to the center of the waveguide with decreasing radius of the rods. This design reduces reflection of electromagnetic waves. Experimental tests demonstrate the efficacy of the design.

Optical Negative-Index Metamaterial Using CSRR by Incidenting the Light Horizontally at Near-Infrared Domain

Metamaterial structure based on cascaded split ring resonators (CSRR) is proposed in order to produce a negative refractive index in terahertz regime at near-infrared range. We have incident light horizontally instead of incidenting it perpendicular. We have measured the negative refractive index, permeability and permittivity by using the S-parameter analysis. Furthermore, it is found out that negative refractive index, permeability and permittivity are dependent upon the width of the wire and the gap between resonators at near-infrared range. This work will be helpful for the fabrication and design of double negative metamaterials structure having negative permeability, permittivity and negative refractive index for in plane applications.

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop （HWIL） simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory （DRFM） system, the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile （HRRP） are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.

Scattering of on-axis polarized Gaussian light beam by spheroidal water coating aerosol particle

Small particle light scattering can produce light with polarization characteristics different from those of the incident beam. An analytical solution to the scattering by a spheroid with inclusion for an on-axis polarized Gaussian beam incidence is provided within the generalized Lorenz-Mie theory framework. The shapes of the inclusion can be spherical, confocal spheroid, or non-confocal spheroid. The Muller scattering matrix elements are computed for plane wave incidence or Gaussian light beam incidence. The effect of the size and shape of the inclusion or the coating on the polarized Oaussian light scattering characteristics by a spheroidal water coating aerosol Darticle are commlted and a,nalvzed.

Study of ~3He inelastic scattering on ^(13)C and ^(14)C at 37.9 MeV

The differential cross sections of elastic and inelastic scattering of ~3He ions on ^（13）C and ^（14）C have been studied at an energy of 37.9 MeV with a double folding model based on M3Y-Reid effective nucleon-nucleon interaction.The resulted parameters have been used for the standard Distorted Wave Born Approximation calculations of angular distributions corresponding to different excitations levels of ^（13）C and ^（14）C and deformation parameters have been deduced.