基于伴随敏感性的风廓线雷达和地基微波辐射计观测对模式预报的影响评估研究

同化大量观测资料可以有效地改进模式预报结果,但不同观测对预报的影响有着显著差异,合理评估观测对预报的贡献是数值模式中最具挑战性的诊断之一。本文采用基于伴随的预报对观测的敏感性(Forecast Sensitivity to Observation,简称FSO)方法,构建WRFDA(Weather Research and Forecasting model’sData Assimilation)框架下的WRFDA-FSO系统。基于2019年9月超大城市项目在北京地区获取的风廓线雷达(Wind Profile Radar,简称WPR)和地基微波辐射计(Microwave Radiometer,简称MWR)观测数据,利用WRFDA-FSO系统,开展观测对WRF模式12 h预报的影响试验,并分析风温湿观测对预报的贡献。结果表明:(1)同化的观测资料(MWR、WPR、Sound、Synop和Geoamv)均减小了WRF模式12 h预报误差,对预报为正贡献,其中MWR观测对预报的影响最大,WPR风场观测对预报的改进效果优于Sound的风场观测。(2)WPR的U、V观测和MWR的T、Q观测中,V观测和T观测对预报的正贡献值更高,对预报的改进效果更优。(3)WPR和MWR多数高度层的观测均减小了预报误差,对预报为正贡献,其中MWR的T观测对预报的正贡献主要位于近地面800 h Pa以下。

Research on Temperature Field of the Support Structure for the Independent LNG Tank

The independent LNG(Liquified Nature Gas)containment is widely used for small or medium-sized LNG carrier and ship using LNG as fuels.The common tank pattern includes single-spherical-cylindrical tank and double-spherical-cylindrical tank,which is the key to design the hull structure and its support.The support is designed to connect the hull structure and LNG tank.Its main functions are heat transferring and force loading.This paper focus on the temperature field distribution of hull and its support structure.The thermal boundary conditions are simulated according to the heat transfer action,such as thermal convection,heat conduction and thermal radiation.The method on how to carry out thermal analysis is presented for an independent LNG containment.The case study is carried out with two typical independent LNG tanks.One is a tank with double spherical cylindrical in the LNG carrier,and the other is a tank with single spherical cylindrical on the deck of the ship using LNG as fuels.The result shows the method presented in this paper is a good reference for the structural design with independent LNG containment.

Characterization and quantification of two acylated flavonol glycosides from Camellia sinensis and their antibacterial effect on oral pathogens

Acylated flavonol glycosides(AFGs)are a new group of flavonoids with multiple pharmacological functions.In the present work,two AFGs were isolated with a combined chromatography technology from Camellia sinensis and identified as quercetin tetraglycosides with one p-coumaryl moiety(F1)and kaempferol tetraglycosides with one p-coumaryl moiety(F2)by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS)and nuclear magnetic resonance(NMR).F1 and F2 with high purity and quantity can be obtained through relatively simple steps,which is of great significance in industrial production and application.The quantification of two AFGs in different tea cultivars and different season samples was conducted using the high-performance liquid chromatography(HPLC)method.Among fifty tested tea cultivars,the contents of F1 and F2 were extremely high in'Zhenghe Dabaicha'and'Wannong 95',but these were undetectable in some tea cultivars.Relatively high contents of AFGs were found in autumn harvested tea samples which might be related to sunlight irradiation.Further in vitro experiments showed that F1 and F2 monomers were effective on inhibiting growth and biofilm development of Porphyromonas gingivalis and Fusobacterium nucleatum.This antibacterial activity was proven to involve the chelation of iron.These results provide useful information on AFGsrich tea resources and new insights of AFGs into effective agents against oral diseases.