In this paper,the Eulerian Stochastic Field(ESF)model in the Transported Probability Density Function(TPDF)class model is combined with the Flamelet Generated Manifolds(FGM)model.This method solves the joint probabili...In this paper,the Eulerian Stochastic Field(ESF)model in the Transported Probability Density Function(TPDF)class model is combined with the Flamelet Generated Manifolds(FGM)model.This method solves the joint probability density function transport equation by ESF method that considers the interaction mechanism between flame and turbulence with high precision.At the same time,by making use of the advantage of the FGM model,this model is able to incorporate the detailed chemical reaction mechanism(GRI 3.0)with acceptable computational cost.The new model has been implemented in the open source CFD suite-Open FOAM.Validation of the model has been carried out by simulating the Sandia flame series(three turbulent piloted methane jet flames)issued by the National Laboratory of the United States.The accuracy and advancement of the ESF/FGM turbulent combustion model are verified by comparing the LES results of the new model with the rich experimental data as well as the RANS results.The results demonstrate that the model has a strong ability in capturing combustion phenomena such as extinction and re-ignition in turbulent flame,which is essential in the accurate prediction of the combustion process in real combustion devices,for example,aircraft engines.展开更多
Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess ...Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.展开更多
针对目前嵌入式系统LCD显示存在需要背光源、视角范围窄、功耗大、响应速度慢等缺点的现状,提出了一种基于单片机的OLED显示系统解决方案。根据上述方案进行了系统硬件和软件设计,该系统以微控制器STC12LE5A60S2作为控制核心,VGG12864L...针对目前嵌入式系统LCD显示存在需要背光源、视角范围窄、功耗大、响应速度慢等缺点的现状,提出了一种基于单片机的OLED显示系统解决方案。根据上述方案进行了系统硬件和软件设计,该系统以微控制器STC12LE5A60S2作为控制核心,VGG12864L作为OLED显示模块,通过Keil u Vision3集成开发环境,采用C51语言设计了MCU应用软件,实现了嵌入式系统中汉字、字符及图片等相关信息的显示功能。经测试验证,该方案具有运行稳定可靠、接口简单、编程方便、功耗低、体积小、成本低、便于维护等优点。展开更多
基金supported by the National Natural Science Foundation of China(No.51706241).
文摘In this paper,the Eulerian Stochastic Field(ESF)model in the Transported Probability Density Function(TPDF)class model is combined with the Flamelet Generated Manifolds(FGM)model.This method solves the joint probability density function transport equation by ESF method that considers the interaction mechanism between flame and turbulence with high precision.At the same time,by making use of the advantage of the FGM model,this model is able to incorporate the detailed chemical reaction mechanism(GRI 3.0)with acceptable computational cost.The new model has been implemented in the open source CFD suite-Open FOAM.Validation of the model has been carried out by simulating the Sandia flame series(three turbulent piloted methane jet flames)issued by the National Laboratory of the United States.The accuracy and advancement of the ESF/FGM turbulent combustion model are verified by comparing the LES results of the new model with the rich experimental data as well as the RANS results.The results demonstrate that the model has a strong ability in capturing combustion phenomena such as extinction and re-ignition in turbulent flame,which is essential in the accurate prediction of the combustion process in real combustion devices,for example,aircraft engines.
基金funded by the West Light Scholar of the Chinese Academy of Sciences(xbzg-zdsys-202202)the Natural Science Foundation of Henan(Grant No.232300420165)Integrated Scientific Investigation of the North-South Transitional Zone of China(2017FY100900)。
文摘Surface-latent heat(LE)and sensible heat(SH)fluxes play a pivotal role in governing hydrological,biological,geochemical,and ecological processes on the land surface in the Tibetan Plateau.However,to accurately assess and understand the spatial distribution of LE and SH fluxes across different underlying surfaces,it is crucial to verify the validity and reliability of ERA-5,GLDAS,and MODIS data against ground measurements obtained from the Flux Net micrometeorological tower network.This study analyzed the spatial patterns of LE and SH over the Tibetan Plateau using data from ERA-5,GLDAS,and MODIS.The results were compared with ground measurements from Flux Net tower observations on different underlying surfaces,and five statistical parameters(Pearson's r,LR slope,RMSE,MBE,and MAE)were used to validate the data.The results showed that:(1)MODIS LE data and ERA-5 SH data exhibited the closest agreement with ground observations,as indicated by their lowest root mean square error and mean bias area values.(2)The accuracy of ERA-5 SH was the highest in meadows and steppes,while GLDAS SH performed optimally in shrublands.Notably,MODIS LE consistently outperformed the other datasets across all vegetation types.(3)The spatial distribution of LE and SH displayed considerable heterogeneity,contingent upon the specific data sources and underlying surfaces.Notably,there was a contrasting trend between GLDAS and ERA-5,as well as MODIS,in terms of SH distribution in the shrubland.In shrublands and meadows,MODIS SH and LE exhibited more pronounced changes than ERA-5 and GLDAS.Additionally,ERA-5 SH demonstrated the opposite variation in meadow and steppe regions compared to GLDAS and MODIS.
文摘针对目前嵌入式系统LCD显示存在需要背光源、视角范围窄、功耗大、响应速度慢等缺点的现状,提出了一种基于单片机的OLED显示系统解决方案。根据上述方案进行了系统硬件和软件设计,该系统以微控制器STC12LE5A60S2作为控制核心,VGG12864L作为OLED显示模块,通过Keil u Vision3集成开发环境,采用C51语言设计了MCU应用软件,实现了嵌入式系统中汉字、字符及图片等相关信息的显示功能。经测试验证,该方案具有运行稳定可靠、接口简单、编程方便、功耗低、体积小、成本低、便于维护等优点。
