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This paper studied the Laser Radar Cross Section (LRCS) of the target scale model by using the Bidirectional Reflection Distribution Function (BRDF) of materials and the Monte Carlo method for reverse ray tracing. The results of the research are shown through data from the satellite scale model. On the basis of the classification of the roughness of different materials and in conjunction with probability density distribution, we adopted a non-uniform sampling method to improve the split-ray collection method in the spatial distribution of scattering energy in the reverse ray tracing algorithm. By conducting the typical Monte Carlo simulation of a simple dihedron and comparing the theoretical calculation results, we tested and verified the correctness of the proposed method. We analyzed the difference between the primary and secondary scattering results of the target LRCS with different conditions. The calculation results show that for rough materials, if only primary scattering is considered in a plurality of detection directions, a large calculation error will occur, so the influence of the secondary scattering must be considered; and the contribution of the diffuse reflection component to the secondary scattering is more significant. Finally, we compared the secondary scattering of different rough materials to describe the circumstances of secondary scattering in which diffuse reflection conditions need to be considered. In addition, the inverse Monte Carlo method used in this paper to calculate the multiple scattering of the LRCS of the target can effectively improve the calculation speed of the acquisition processing. This improves the reliability of the calculation results while taking into account the estimated speed.

The hexa-fructopyranoside was synthesized with N-phenyltrifluoroacetimidate glycosylation. The synthesis was achieved by regioselective glycosylation on the 1-OH of fructopyranosyl acceptor. Fructosyl oligosaccharides were elongated with β-(2 → 1)-difructopyranosyl unit in every two steps, without any further protection/deprotection step. This work proved N-phenyltrifluoroacetimidate glycosylation a practical method for oligo-fructopyranoside synthesis.

A 10-day ocean observation experiment was carried out at the Bohe Marine Meteorological Science Experimental Base in Maoming, Guangdong. The mid-wave and long-wave infrared radiation images of the ocean were measured on the marine observation platform and the coastal land observation platform. In order to analyze the variation of sea surface radiation characteristics with time, the experiment planned a 24-hour measurement. At the same time of infrared radiation measurement, the meteorological parameters such as wind speed, wind direction, temperature and humidity were recorded. Based on the measurement data of October 1, 2018, the characteristics of ocean infrared radiation are statistically analyzed, which is consistent with the actual situation. The radiation characteristics of mid-wave infrared and long-wave infrared in the sea surface are compared and analyzed.

China–US relations will stagnate in a strategic game for some time to come and even for a long historical period. ASEAN will find itself confronted with a new problem and a new challenge as it has to navigate through this situation and cope with inter-state relations and international affairs under this context. As the largest neighbor of China and a main partner to the US in Asia, ASEAN insists on “not choosing any side” and sticks to the “balance of power”. The intensified China–US game has some potential impact on China-ASEAN relations. Securing the centrality of ASEAN in regional cooperation not only helps maintain lasting peace, stability and prosperity in Southeast Asia, but also is in line with the long-term strategic interests of China and the US in the region. China will continue to support the centrality of ASEAN in regional cooperation, promote deep integration of the “Belt and Road” initiative with different institutional arrangements that ASEAN makes for regional integration, and give positive considerations to building production bases in Southeast Asia to improve its global industrial chain.

When a laser is transmitted in fog, and the water droplets will scatter and absorb the laser, which affects the intensity of the laser transmission and the accuracy of radar detection. Therefore, it is of great significance to study the laser transmission in the fog. At present, the main method of calculating the scattering and attenuation characteristics of fog is based on the radiation transmission theory, which is realized by a large number of numerical calculations or physical simulation methods, which takes time and cannot meet the requirements for obtaining the fast and accurate results. Therefore, in this paper established are a new laser forward attenuation model and backward attenuation model in low visibility fog. It is found that in low visibility environments, the results calculated by the Monte Carlo method are more accurate than those from most of the existing forward attenuation models. For the cases of 0.86-μm, 1.06-μm, 1.315-μm, 10.6-μm typical lasers incident on different fogs with different visibilities, a backscatter model is established, the error between the fitting result and the calculation result is analyzed, the backward attenuation fitting parameters of the new model are tested, and a more accurate fitting result is obtained.

With the rapid development of the fifth-generation (5G) mobile communication technology, the application of each frequency band has reached the extreme, causing mutual interference between different modules. Hence, there is a requirement for detecting filtering and preventing interference. In the troposphere, over-the-horizon propagation occurs in atmospheric ducts and turbulent media. The effects of both ducting and turbulence can increase the probability of occurrence of long-distance co-channel interference (CCI), in turn, severely affecting the key performance indicators such as system access, handover and drop. In the 5G era, to ensure communication channels and information security, CCI must be reduced. This paper introduces a scattering parabolic equation algorithm for calculating signal propagation in atmospheric ducts on irregular terrain boundaries. It combines Hitney’s radio physical optical model and Wagner’s nonuniform turbulent scattering model for calculating the tropospheric scattering in an evaporation duct or a surface-based duct. The new model proposes a tropospheric scattering parabolic equation algorithm for various tropospheric duct environments. Finally, as a specific case, the topographical boundaries between several cities in the East China Plain were considered, and the over-the-horizon propagation loss was simulated for various ducting and turbulent environments. The simulation results were used to evaluate whether CCI would occur between cities in a specific environment.

The laser radar cross section (LRCS) is a key parameter in the study of target scattering characteristics. In this paper, a practical method for calculating LRCSs of rotationally symmetric targets is presented. Monostatic LRCSs for four kinds of rotationally symmetric targets (cone, rotating ellipsoid, super ellipsoid, and blunt cone) are calculated, and the results verify the feasibility of the method. Compared with the results for the triangular patch method, the correctness of the method is verified, and several advantages of the method are highlighted. For instance, the method does not require geometric modeling and patch discretization. The method uses a generatrix model and double integral, and its calculation is concise and accurate. This work provides a theory analysis for the rapid calculation of LRCS for common basic targets.

Propagation characteristics of oblique incident terahertz wave from the nonuniform dusty plasma are studied using the propagation matrix method. Assuming that the electron density distribution of dusty plasma is parabolic model, variations of power reflection, transmission, and absorption coefficients with frequencies of the incident wave are calculated as the wave illuminates the nonuniform dusty plasma from different angles. The effects of incident angles, number density, and radius of the dust particles on propagation characteristics are discussed in detail. Numerical results show that the number density and radius of the dust particles have very little influences on reflection and transmission coefficients and have obvious effects on absorption coefficients. The terahertz wave has good penetrability in dusty plasma.

Scattering characteristics of space target in the visible spectrum, which can be used in target detection, target identification, and space docking, is calculated in this paper. Algorithm of scattering characteristics of space target is introduced. In the algorithm, space target is divided into thousands of triangle facets. In order to obtain scattering characteristics of the target, calculation of each facet will be needed. For each facet, calculation will be executed in the spectrum of 400-760 nanometers at intervals of 1 nanometer. Thousands of facets and hundreds of bands of each facet will cause huge calculation, thus the calculation will be very time-consuming. Taking into account the high parallelism of the algorithm, Graphic Processing Units (GPUs) are used to accelerate the algorithm. The acceleration reaches 300 times speedup on single Femi-generation NVDIA GTX 590 as compared to the single-thread CPU version of code on Intel(R) Xeon(R) CPU E5-2620. And a speedup of 412x can be reached when a Kepler-generation NVDIA K20c is used.

This paper describes the electromagnetic scattering model with concrete pavement and scattering properties of layered equivalent to a single exponential model of the electromagnetic spectrum engineering rough surface scattering, and then introduced the experimental method to measure the scattering coefficient of cement, the experimental apparatus and measurement system, and then later by the experimental scattering data obtained from the cement floor, Based on experimental data, we can obtained these parameters through the genetic algorithm, and then these parameters were carried into the formula to calculate the theoretical bistatic scattering coefficients, thus obtained bistatic scattering coefficients. Finally, this paper present several statistical models, based on genetic algorithms to optimizing the bistatic scattering data fitting and establish an empirical model.

A backscattering model of average signal power function for laser radar range imagery obtained by a short pulse laser for a coarse cone is presented in this paper. This model can analyze the laser range profile and range imaging which relate the average power seen by the receiver with laser pulse, target shape, optical scattering properties of surface material, incidence angle and other factors. Simulation of the laser range profile and range imaging of a coarse cone is given. Based on the results of the simulated model and theoretical analysis, the cone can be identified. The model can be used for demonstration of 3D laser radar system and can also be used to generate library of model data sets for automatic target recognition.

starting from the sports theory course---football theory teaching, this paper studies the application of multi-media, which will pose challenges for the traditional single football teaching and training mode, and become the inevitable trend of future teaching as well as the training reform and development. This paper adopts research methods like literature review, video observation, expert interview and software programming to introduce the multi-media technology into the football theory teaching, and offer students a brand-new and vivid environment for teaching. Keywordsmulti-media technology; sports theory Currently, as the modern teaching and training means, computer multi-media technology is applied more and more widely. The teachers have also generally experienced the convenience and efficiency of modern multi-media technology in the teaching. The multi-media teaching means to integrate the various media information kinds (such as text, image, sound, etc.) on the screen, and help learners to complete a series of man-machine interactive operation for study through interactive interface. The application of teaching and training courseware modes in the football teaching will pose challenges for the traditional single football teaching and training mode, and become the inevitable trend of future teaching as well as the training reform and development. I. RESEARCH CONTENTS, OBJECTS AND METHODS A. Research contents The main research contents of this paper are: (I) the detailed contents and basic characteristics of football passing tactics in the theory teaching; (II) the design methods of multi-media courseware in the theoretical teaching of football passing tactics; (III) the application effect analysis of multi-media courseware in the theoretical teaching of football passing tactics.

We report here a backscattering model of average signal power function (SPF) for laser radar 3D range imagery obtained by arrays of detectors for arbitrary coarse targets. The model relates the average power seen by the receiver with laser pulse, target shape, optical scattering properties of surface material, incidence angle and other factors. The optical scattering property of the material is characterized by bidirectional reflectance distribution function (BRDF). The model can be used for demonstration of 3D laser radar system and can also be used to generate library of model data sets for automatic target recognition (ATR). Finally, Compute Unified Device Architecture (CUDA) is introduced for parallelizing these algorithms. The acceleration reaches 56 times speedup on single Fermi-generation NVIDIA GTX 480 as compared to the traditional CPU version of code on Intel i7 930 CPU.

A new semi-empirical seven-parameter BRDF model is developed in the UV band using experimentally measured data. The model is based on the five-parameter model of Wu and the fourteen-parameter model of Renhorn and Boreman. Surface scatter, bulk scatter and retro-reflection scatter are considered. An optimizing modeling method, the artificial immune network genetic algorithm, is used to fit the BRDF measurement data over a wide range of incident angles. The calculation time and accuracy of the five- and seven-parameter models are compared. After fixing the seven parameters, the model can well describe scattering data in the UV band.

An experiment measuring system is introduced. Angle-resolved single-band and multispectral bidirectional reflectance distribution function measurements are operated in ultraviolet band. Hemisphere spectral reflectivity of some samples is measured. An optimizing modeling method, particle swarm optimization (PSO) is used to model the laser BRDF data of typical samples. The results are fitted with the models developed above using optimize algorithm to get the parameters. Spectral BRDF of samples calculated with the model are in good agreement with the measured data. And these studies about measuring and optimizing modeling of typical roughness target samples in ultraviolet band have significant meanings in a lot of related fields.

An automatic measurement device is developed to measure Spectral Bidirectional Reflectance Distribution Function (BRDF) of various samples in the band from 400 to 2000 nm. Spectral BRDF of two kinds of solar panels (silicon solar panel and gallium arsenide solar panel) used on satellite is measured. Spectral Directional Hemisphere Reflectance (DHR) of the solar panels is measured in the band from 400 to 1800 nm. Measured data of the two kinds of solar panel exhibit a high specular reflection nature and a total hemisphere reflectance lower than 0.1 in the band from 400 to 1000 nm. Specular peaks of gallium arsenide solar panel are higher and narrower than those of silicon solar panel in the measured data of spectral BRDF. DHR of silicon solar panel increases to approximately 0.6 quickly at wavelength greater than 1000 nm. As to gallium arsenide solar panel, DHR remains below 0.3 in the band from 1000 to 1800 nm.

A brief introduction of the measuring system and methodology of the laser scattering from target is presented in this paper. The laser scattering characteristics of the reference standard plate (PTFE) and the flat plate with green camouflage paint are measured indoor. By analyzing the measured data, we obtained the directional hemispherical reflectance and Laser Radar Cross Section (LRCS) per unit area of the reference standard plate based on the angular distribution of laser bistatic scattering intensity. The Laser Radar Cross Section per unit area of the flat plate with green camouflage paint is obtained by analyzing the data from reference-sample method measurement. Lastly, by using genetic simulated annealing algorithms, the statistic model of the laser scattering angular distribution is given.

The second-order and fourth-order statistical moments of the speckle field from a diffuse target in atmospheric turbulence are studied which have great influence on the performance of lidar systems. By expanding a general rotationally symmetric beam as a sum of Gaussian?Schell model (GSM) beams, the mean intensity of the general beam propagating over a distance in an atmospheric turbulence is formulated. Expressions for the degree of coherence (DOC) and the normalized intensity variance of the scattered field of a general beam from a rough surface in turbulence are derived based on the extended Huygens?Fresnel principle. The general expressions reduce to the well-known forms for a GSM beam. Another example for the general beam used in this paper is the collimated flat-topped beam. The results of both kinds of beams show that the intensity profile on the target plane is a key factor affecting the statistical characteristics of the speckle field. A larger beam spot on the target plane induces a smaller coherence length and a smaller normalized intensity variance of the received field. As turbulence gets stronger, the coherence length becomes smaller, and the normalized intensity variance firstly increases and declines to unity finally.