Effects of finite inner and outer scales on the scintillation index of turbulent slant path

In this paper, the effects of nonzero inner scales and finite outer scales are investigated, in the context of Gaussian beam propagation along a slant path under general turbulence conditions. Theoretical expressions for the cut-off spatial frequencies are derived with an approach method, and thereby a modified scintillation model is developed to incorporate inner scale and outer scale parameters in the analysis. Then, inner and outer scale effects on the downlink are analysed with respect to the zenith angle, the altitude of the transmitter, the initial beam radius, as well as the turbulence strength. Numerical results indicate that the effects of a finite outer scale mainly influence transmission that occurs at large zenith angles or high altitudes, while the inner scale effects are more prevalent. This study may be helpful to improve the accuracy of calculation of slant-path scintillation index, and thus benefit the characterization and optimization of space/air-ground laser communication systems.     

安定剂废水处理研究

采用常压精馏和活性炭吸附相结合的方法处理N–甲基对硝基苯胺和2–硝基二苯胺的生产污水,取得了较好的效果。通过试验探索将2种废水共用1套处理装置,提高了设备利用率,处理后的废水无色、无味,COD小于100 mg/L,可直接排放或循环使用。     

Development of a mathematical model for optimizing a heliostat field layout using differential evolution method

In this study, differential evolution was employed to perform optimization of a heliostat field. A complete mathematical code was developed for this purpose, which generates a heliostat field and calculates the optimum spacing between heliostats through differential evolution optimization technique. The optimization was executed for two sets of two cases and compared with an un‐optimized case. In the first case, only the optical performance was optimized, whereas in the second case, the normalized ratio of the optical performance to the land area covered by the heliostat field was maximized. In the first set of cases, the extra security distance between the heliostats was neglected, whereas in the second set of cases, the extra security distance was taken into account. To apply and examine the application of the optimization algorithm developed, 3 days of the year were selected: March 21, June 21, and December 21, considering Dhahran, Saudi Arabia as an illustrative example. For June 21, when the extra security distance between the heliostats is neglected, the optical efficiency of the un‐optimized case was 0.6026, while for the first optimized case, it was 0.6395, and for the second optimized case, it was 0.6033. However, when the extra security distance was considered, the optical efficiency of the un‐optimized case was 0.6167; while for the first optimized case, it was 0.6241, and for the second optimized case, it was 0.6167. Similar observations were realized for the other cases selected. Copyright © 2015 John Wiley & Sons, Ltd.     

Atmospheric Oxidation Mechanism and Kinetic Studies for OH and NO3 Radical-Initiated Reaction of Methyl Methacrylate

The mechanism for OH and NO₃ radical-initiated oxidation reactions of methyl methacrylate (MMA) was investigated by using density functional theory (DFT) molecular orbital theory. Geometrical parameters of the reactants, intermediates, transition states, and products were fully optimized at the B3LYP/6-31G(d,p) level. Detailed oxidation pathways were presented and discussed. The rate constants were deduced by the canonical variational transition-state (CVT) theory with the small-curvature tunneling (SCT) correction and the multichannel Rice-Ramspergere-Kassele-Marcus (RRKM) theory, based on the potential energy surface profiles over the general atmospheric temperature range of 180–370 K. The calculated results were in reasonable agreement with experimental measurement.     

External Weather Data Assimilation to Simulate Wind and Temperature Fields in the Region of Gualeguaych~, Argentina

This work shows the comparison between the results of wind and temperature simulation and data weather measurements in low layers near Gualeguaychfi City, Argentine, for 12 h in January 1, 2011. The model ARPS （advanced regional prediction system） with two options in the boundary conditions is used. In such conditions, wave-radiating open （radiative） with relaxation to the initial state were used while otherwise used absorbing boundary conditions data forced from MBLM （meso-scale boundary layer model） operational forecasters used by the National Weather Office. The results of both simulations are compared with data measured by three weather stations located around of the Uruguay River. As both simulations are initialized using the same data, there is a better agreement between the values obtained by forcing the boundary conditions for which are using ＂radiative＂ boundary conditions after 2 h physical time from the start of the simulation.     

Modeling OH transport phenomena in cold plasma discharges using the level set method

Cold atmospheric plasmas (CAPs) have attracted considerable interest in the field of plasma medicine. Generated reactive species such as hydroxyl (OH) species play an important role in applications of CAPs. Transportation of OH species towards the target and distribution of these OH species in the plasma plume play an important role in the applications of plasma medicine. In the present work, a computational model was built to simulate the transportation and distribution of OH species in CAP discharges, which was based on the level set method to dynamically track the propagation of plasma carrier gas in air. A reaction term was incorporated for the OH species. The OH species tended to diffuse around the main stream of the carrier gas, and thus covered larger radial and axial distances. A CAP discharge onto a skin layer led to the largest accumulation of OH species at the central part of the exposed area. The distribution of OH species on the skin was asymmetric, which agreed with experiments. The computational model itself and the obtained results would be useful for future development of plasma medicine.     

一种新型高精度大气压力传感器的研究

采用SOI(silicon-on-insulator)材料,设计并制作了双岛敏感结构,通过绝缘层隔离,消除PN结噪声,提高信噪比、线性度及重复性。利用敏感电阻的温度特性直接测量环境温度,进行温度补偿,提高了补偿的准确性,最后通过试验数据说明传感器的精度达到了气象使用要求。     

基于线性光谱分解的遥感图像大气灰霾环境效应去除技术

灰霾环境对遥感图像具有非常严重的影响。主要分析了太阳光在灰霾环境中的传输方法。根据太阳光的传输方式,把灰霾层看作是一个不均匀的半透明-透明层。然后通过SMACC算法提取灰霾的端元信息,并利用最小二乘法反演去除灰霾后的遥感图像。本文所述的线性光谱分解去霾方法对遥感图像中气溶胶浓度低/高的灰霾的去除效果都比较好,而且较大限度地保留了图像的光谱信息。最后把本文方法和大气校     

激光雷达探测大气边界层高度分布的梯度法应用研究

为了研究合肥地区大气边界层结构变化特征,利用偏振拉曼-米散射激光雷达进行了连续探测.首先介绍利用激光雷达回波信号提取大气边界层高度的梯度法,并分析该方法的优缺点.然后对梯度法进行修正,给出具体的实例分析及对比结果.最后利用修正后的梯度法对激光雷达连续测量数据进行大气边界层高度提取,得到合肥地区观测站上空大气边界层的高度分布及时间变化特征.结果表明,实验期间合肥地区的大气边界层高度主要分布在1～1.5 km范围内,平均高度约为(1.28±0.2) km.