异常性检测算法在引信干扰信号识别中的应用

目的 解决传统分类引信抗干扰算法因干扰信号难获取、特征信号样本少、正负样本数不平衡而导致计算精度低的问题,克服引信抗干扰算法对样本的依赖性,并提高引信信号识别准确率。方法 通过WVD时频变换的方法,将拆分后的真实含扰引信信号切片进行重组,使其由一维时序信号向二维图片信息进行扩展,基于数据倍增策略,提升算法泛化性,并降低其对真实数据样本的依赖。融合GANomaly与EfficientNet网络,在扩充的引信数据集上进行线下干扰信号特征学习,并对含扰引信图像数据进行线上异常性判断与干扰信号识别。结果 GE-FS网络能够在真实引信小样本信号的基础上进行有效数据扩充,基于扩充数据训练后,引信含扰识别准确率达到98.4%。结论 GE-FS网络能有效针对引信异常信号进行精确检测与识别,可以增强引信系统的抗干扰能力与作战自适应性。     

The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01381-1) contains supplementary material, which is available to authorized users.     

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China, 2004-2010

The nitrate-nitrogen(NO 3-N) concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations,representing typical agroand forest ecosystems,were assessed using monitoring data collected between 2004 and 2010.Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater,and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made.Results indicated that most of the NO 3--N concentrations in groundwater from the agroand forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard:Quality Standard for Ground Water(≤ 20 mg/L).Over the study period,the average NO 3--N concentrations were significantly higher in agro-ecosystems(4.1 ± 0.33 mg/L) than in forest ecosystems(0.5 ± 0.04 mg/L).NO 3-N concentrations were relatively higher(> 10 mg N /L) in 10 of the 43 wells sampled in the agricultural ecosystems.These elevated concentrations occurred mainly in the Ansai,Yucheng,Linze,Fukang,Akesu,and Cele field sites,which were located in arid and semiarid areas where irrigation rates are high.We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.     

我国二恶英和多氯联苯的研究现状及对策分析

为了解二恶英(PCDD/Fs)和多氯联苯(PCBs)在中国的研究水平、研究能力和驱动力,本文对有关研究论文的数量、题材、内容、资助来源和研究机构进行了系统调查和分析。调查发现,国内相关研究尚处在起步阶段,研究的方向和重点还需要进一步调整,研究能力有限,研究机构间合作交流不充分。针对这些问题,提出了相应的对策建议。     

有机物渗透管的研制

介绍了用Wh聚四氟乙烯膜作为渗透材料制作有机物渗透管的方法,并且针对所研制的渗透管的特性、影响渗透率的主要因素及渗透率的稳定性等方面进行了探讨.     

宜昌市城区灰霾天气成因分析研究

从灰霾天气形成的可能影响因素出发,根据长期的气象和环保观测资料,将近10年来宜昌市城区逆温层与等温层、降水日、风速风向、环境空气质量优良天数、可吸入性颗粒物(PM10)年均值、二氧化硫(SO2)年均值、二氧化氮(NO2)年均值的观测值与灰霾日观测值进行相关分析,并分析了宜昌市城区环境污染的气象化学作用,揭示出宜昌市城区灰霾天气成因主要是与不利扩散和降解的气象化学作用有关,与目前环境空气质量监测的PM10、SO2、NO2三个指标无明显相关关系,而与细粒子、气溶胶污染有关。     

道路交通噪声自动监测中最少监测时间研究

以城市主干线为例,对长期道路交通噪声自动监测数据进行统计分析,得出道路交通噪声实施噪声自动监测时应采用的小时最少监测时间、日昼夜最少监测小时、季最少监测天数和年最少监测天数。