Presence of Fusarium toxins in maize from Autonomous Province of Vojvodina,Serbia

Fusarium toxins are recognized as worldwide concern since those contaminants may potentially affect human and animal health and could also be a cause of great economical losses. The aim of this study was to determine the presence of the following Fusarium toxins: fumonisins (FUMs), deoxynivalenol (DON), zearalenone (ZEA) and sum of T-2/HT-2 toxins in maize. A total of 90 samples were collected during the harvest 2012 from four different maize growing areas in Autonomous Province of Vojvodina, Serbia. Analysis showed that 100%, 53.3% and 2.22% of examined maize samples were contaminated with FUMs, T-2/HT-2 and DON with median values of 1606, 35.3 and 650 μg/kg, respectively. None of the maize samples was contaminated with ZEA. Differences in the occurrence of investigated Fusarium toxins could be explained by different conditions required for their growth and synthesis of the toxins. Maize growing season 2012 was characterized by drought conditions. Hot and dry weather conditions were particularly favorable for FUMs production. This is the first report of the natural co-occurrence of FUMs, T-2/HT-2, ZEA and DON in maize from Serbia.     

POLDER 多角度、多通道偏振探测器对地遥感观测研究进展

由法国空间研究中心(CNES) 于2004 年12 月18 日发射的PARASOL (Polarization &Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) 卫星, 是法国和美国合作的“卫星列车”(“A-Train ”) 计划中的一员, 上面主要搭载了POLDER(Polarization and Directionality of the Earth’s Reflectances) 仪器, 可以通过全球观测, 从空间收集地气系统反射太阳辐射的偏振性和方向性数据。从这些数据, 我们可以获得地表、大气气溶胶及云的多种特性, 这些信息是改进气候数值模式所必需的。主要以POLDER 仪器为例, 就多光谱、多角度和多偏振联合遥感观测地气系统方面的进展进行综述。     

基于遗传算法的测试用例自动生成及其改进方法

遗传算法是一种通用的自适应搜索算法。它给测试用例自动生成问题带来了新的解决思路。但是传统的遗传算法应用于测试用例自动生成,重组、突变的随机性容易使种群中多样性遭到破坏,使得算法搜索空间减小,从而导致算法错误地收敛到局部最优值。而且盲目的随机重组和突变又使得搜索的效率非常低。本文介绍一种改进方法,引进突变控制策略和优化解控制策略,可有效提高遗传算法的搜索能力和获取最优解的性能。     

Synergetic use of POLDER and MODIS for multilayered cloud identification

The purpose of this study is to investigate the possibility of identifying overlapping clouds that contain thin cirrus overlying a lower-level water cloud by synergetic use of POLDER-3 (Polarization and Directionality of the Earth Reflectance) and MODIS (MODerate resolution Imaging Spectroradiometer) data. When thin cirrus clouds overlap the liquid cloud layer, the liquid information may be obtained by POLDER observations and the presence of the cirrus may be inferred from the MODIS CO₂-slicing technique. An initial comparison of the POLDER cloud phase and the MODIS cloud-top pressure for one scene over East Asia also shows that a large portion of clouds declared as liquid water clouds by POLDER-3 correspond to the lower cloud-top pressures derived from MODIS. As a result, an overlapped cloud identification method is proposed under the assumption that the multilayered cloud would be present if the POLDER cloud phase is liquid water and the MODIS cloud-top pressure is less than 500 hPa. For the studied scene, the comparison of the multilayered cloud identification results with CloudSat and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations illustrates that the proposed method could detect multilayered clouds when the upper cirrus has a visible optical thickness of less than 2.0. Then the identification results are compared with the MODIS Cloud_Multi_Layer_Flag. It is indicated that the consistency between the multilayered clouds from the proposed synergy and MODIS-operational algorithm increases gradually from over 40% to nearly 100% with the increase of the confidence level of the MODIS multilayered clouds from the lowest to the highest. Further analysis suggests that the majority of multilayered clouds falsely classified as single-layered clouds by the proposed method may correspond to relatively thick cirrus covering lower-level water clouds. Additionally, an index by using the multilayered cloud detection differences from the two methods is proposed to provide some information on the optical thickness of the cirrus covering lower-level water cloud. Finally, quantitative comparisons are extended to four other scenes at different locations by using active measurements. The results also show that the mean visible optical thickness of the high-level clouds of the multilayered clouds detected by both methods (1.57) is remarkably less than that by only MODIS-operational method (2.84), which means that the differences between the results from the two methods are mainly caused by the different sensitivities to the visible optical thickness of the high-level cloud and could be used to indicate the range of the visible optical thickness of the cirrus clouds covering the lower-level water clouds.     

一种基于海面背景的WindSat极化通道替代定标方法研究

凭借能够测量海面辐射全部4个Stokes参数的能力,全极化微波辐射计成为测量海面风场的一种新手段。由于风向信号仅仅只有几K甚至更小的振幅,故对全极化微波辐射计极化通道的定标精度要求颇高。使用WindSat实测亮温及其海面参数匹配数据集,基于海面风向信号的谐波特征,对WindSat极化通道亮温的定标偏差和仪器噪声进行了计算和分析。研究结果表明:WindSat的10.7、18.7和37.0 GHz这3个频率的极化通道均存在明显的定标偏差,并且该定标偏差会随着升轨和降轨、前向刈幅和后向刈幅等不同观测模态发生变化。另外,WindSat极化通道的仪器噪声较小,其中T3的仪器噪声在0.2 K以内,T4的仪器噪声在0.1 K以内。     

基于能量平衡估算陆地近地层光学湍流

估算陆地近地层光学湍流通常需要利用两层不同高度的气象观测,而常规气象观测通常只有一层。为了利用单层常规气象观测估算陆地近地层光学湍流,通过采用Shapiro给出的利用常规气象要素估算地面太阳辐射的经验模型,以及美国陆军统一土壤分类方案,基于地面能量平衡,建立一个陆地近地层光学湍流估算模型。首先通过数值求解土壤热传导方程估算土壤温度,再基于地面能量平衡估算地面温度、基于强迫恢复方法估算地面湿度;最后,将估算的地面温度和湿度看作是粗糙度高度的温度与湿度,结合常规单层气象观测数据,估算光学湍流强度。实例计算表明：该方法估算的光学湍流强度整体上与利用两层气象观测估算的光学湍流强度基本一致。     

几种海水微波复介电常数模型的比较和分析

海水的复介电常数是计算海面发射率的重要输入参数之一。迄今为止,已经发布了许多经典的海水复介电常数计算模型,并被广泛应用在星载微波海洋遥感领域。首先回顾了经典的海水微波复介电常数模型,指出了它们的主要性能特点和彼此之间的差异;接着,使用卫星观测数据以及相匹配的大气海洋环境产品,通过比对模型计算亮温和卫星实测亮温,分析了当前5个海水微波复介电常数模型的计算准确度。结果表明：Fastem5中的海水微波复介电常数模型计算准确度相对较高,运行速度较快。     

Airborne Experiment of TG-2 Multi-angle Polarization Imager for Cloud Phase Identification

Multi\|angle polarization measurement technology can be used to detect cloud and aerosol information,and it barely depends on prior temperature information.In order to verify capability of cloud phase classification from the TG\|2 Multi\|angle Polarization Imager developed independently by China,the results of first airborne observation experiment of Multi\|angle Polarization Imager for cloud observations were compared with the results of numerical simulation under typical conditions.The libRadtran model simulation shows that the water cloud has the maximum polarized radiation (primary rainbow) for scattering angles near 140°.The results based on radio sounding and microwave radiometer show that there are water cloud under 3.7 km height of the research area.Meanwhile,the Multi\|angle Polarization Imager accurately captures the character of maximum polarized radiation of water cloud droplet (primary rainbow) near 140° scattering angles.In addition,the corresponding MODIS observation data also shows there exists a large scale of water cloud near the research area.Above results comprehensively indicate the Multi\|angle Polarization Imager has the function of cloud phase recognition without relying on prior information,and this test lays the foundation for the further study of the space\|based polarization observations of cloud phase.     

全极化微波信号海面风场反演技术现状与发展趋势

全极化微波辐射计是一种新型的被动微波遥感仪器,可以测量海面辐射的全部4个Stokes参数,提供了测量海面风场的一种新方法。首先介绍了国内外先进微波辐射计的技术特点及其海洋遥感应用情况,然后描述了海面微波发射信号的变化机理,以及海面全极化信号的风向谐波特征及其反演海面风场的优势,归纳了全极化微波信号海面风场反演的总体技术思路和产品精度,最后分析了全极化微波辐射计风场反演的关键技术和难点,并对该项技术的发展进行了展望。