Model-Based Development has become an industry wide standard paradigm.As an open source alternative,Scilab/Xcos is being widely employed as a hybrid dynamic systems modeling tool.With the increasing efficiency in impl...Model-Based Development has become an industry wide standard paradigm.As an open source alternative,Scilab/Xcos is being widely employed as a hybrid dynamic systems modeling tool.With the increasing efficiency in implementation using graphical model development and code generation,the modeling and simulation community is struggling with assuring quality as well as maintainability and extendibility.Refactoring is defined as an evolutionary modernization activity where,most of the time,the structure of the artifact is changed to alter its quality characteristics,while keeping its behavior unchanged.It has been widely established as a technique for textual programming languages to improve the code structure and quality.While refactoring is also regarded as one of the key practices of model engineering,the methodologies and approaches for model refactoring are still under development.Architecture-Driven Modernization(ADM)has been introduced by the software engineering community as a model-based approach to software modernization,in which the implicit information that lies in software artifacts is extracted to models and model transformations are applied for modernization tasks.Regarding refactoring as a low level modernization task,the practices from ADM are adaptable.Accordingly,this paper proposes a model-based approach for model refactoring in order to come up with more efficient and effective model refactoring methodology that is accessible and extendable by modelers.Like other graphical modeling tools,Scilab/Xcos also possesses a formalized model specification conforming to its implicit metamodel.Rather than proposing another metamodel for knowledge extraction,this pragmatic approach proposes to conduct in place model-to-model transformations for refactoring employing the Scilab/Xcos model specification.To construct a structured model-based approach,the implicit Scilab/Xcos metamodel is explicitly presented utilizing ECORE as a meta-metamodel.Then a practical model transformation approach is established based on Scilab scripting.A Scilab toolset is provided to the modeler for in-place model-to-model transformations.Using a sample case study,it is demonstrated that proposed model transformation functions in Scilab provide a valuable refactoring tool.展开更多
Prior to hardware implementation, simulation is an important step in the study of systems such as Direct Sequence Code Division Multiple Access (DS-CDMA). A useful technique is presented, allowing to model and simulat...Prior to hardware implementation, simulation is an important step in the study of systems such as Direct Sequence Code Division Multiple Access (DS-CDMA). A useful technique is presented, allowing to model and simulate Linear Feedback Shift Register (LFSR) for CDMA. It uses the Scilab package and its modeling tool for dynamical systems Xcos. PN-Generators are designed for the quadrature-phase modulation and the Gold Code Generator for Global Positioning System (GPS). This study gives a great flexibility in the conception of LFSR and the analysis of Maximum Length Sequences (MLS) used by spread spectrum systems. Interesting results have been obtained, which allow the verification of generated sequences and their exploitation by signal processing tools.展开更多
Measurements of column-averaged dry-air mole fractions of carbon dioxide and carbon monoxide,CO_(2)(XCO_(2))and CO(XCO),were performed throughout 2019 at an urban site in Beijing using a compact Fourier Transform Spec...Measurements of column-averaged dry-air mole fractions of carbon dioxide and carbon monoxide,CO_(2)(XCO_(2))and CO(XCO),were performed throughout 2019 at an urban site in Beijing using a compact Fourier Transform Spectrometer(FTS)EM27/SUN.This data set is used to assess the characteristics of combustion-related CO_(2)emissions of urban Beijing by analyzing the correlated daily anomalies of XCO and XCO_(2)(e.g.,ΔXCO andΔXCO_(2)).The EM27/SUN measurements were calibrated to a 125HR-FTS at the Xianghe station by an extra EM27/SUN instrument transferred between two sites.The ratio ofΔXCO overΔXCO_(2)(ΔXCO:ΔXCO_(2))is used to estimate the combustion efficiency in the Beijing region.A high correlation coefficient(0.86)betweenΔXCO andΔXCO_(2)is observed.The CO:CO_(2)emission ratio estimated from inventories is higher than the observedΔXCO:ΔXCO_(2)(10.46±0.11 ppb ppm^(−1))by 42.54%-101.15%,indicating an underestimation in combustion efficiency in the inventories.DailyΔXCO:ΔXCO_(2)are influenced by transportation governed by weather conditions,except for days in summer when the correlation is low due to the terrestrial biotic activity.By convolving the column footprint[ppm(μmol m-2 s-1)-1]generated by the Weather Research and Forecasting-X-Stochastic Time-Inverted Lagrangian Transport models(WRF-X-STILT)with two fossil-fuel emission inventories(the Multi-resolution Emission Inventory for China(MEIC)and the Peking University(PKU)inventory),the observed enhancements of CO_(2)and CO were used to evaluate the regional emissions.The CO_(2)emissions appear to be underestimated by 11%and 49%for the MEIC and PKU inventories,respectively,while CO emissions were overestimated by MEIC(30%)and PKU(35%)in the Beijing area.展开更多
Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of differ...Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.展开更多
We analyze sea ice changes from eight different earth system models that have conducted experiment abrupt4xCO2 of the Coupled Model Intercomparison Project Phase 5 （CMIP5）. In response to abrupt quadrupling of CO2 f...We analyze sea ice changes from eight different earth system models that have conducted experiment abrupt4xCO2 of the Coupled Model Intercomparison Project Phase 5 （CMIP5）. In response to abrupt quadrupling of CO2 from preindustrial levels, Arctic temperatures dramatically rise by about 10℃--16℃ in winter and the seasonal sea ice cycle and sea ice concentration are significantly changed compared with the pre-industrial control simulations （piControl）. Changes of Arctic sea ice concentration are spatially correlated with temperature patterns in all seasons and highest in autumn. Changes in sea ice are associated with changes in atmospheric circulation patterns at heights up to the jet stream. While the pattern of sea level pressure changes is generally similar to the surface air temperature change pattern, the wintertime 500 hPa circulation displays a positive Pacific North America （PNA） anomaly under abrupt4xCO2-piControl. This large scale teleconnection may contribute to, or feedback on, the simulated sea ice cover change and is associated with an intensification of the jet stream over East Asia and the north Pacific in winter.展开更多
We present a study on the retrieval sensitivity of the column-averaged dry-air mole fraction of CO2(XCO2) for the Chinese carbon dioxide observation satellite(TanSat) with a full physical forward model and the optimal...We present a study on the retrieval sensitivity of the column-averaged dry-air mole fraction of CO2(XCO2) for the Chinese carbon dioxide observation satellite(TanSat) with a full physical forward model and the optimal estimation technique. The forward model is based on the vector linearized discrete ordinate radiative transfer model(VLIDORT) and considers surface reflectance, gas absorption, and the scattering of air molecules, aerosol particles, and cloud particles. XCO2 retrieval errors from synthetic TanSat measurements show solar zenith angle(SZA), albedo dependence with values varying from 0.3 to 1 ppm for bright land surface in nadir mode and 2 to 8 ppm for dark surfaces like snow. The use of glint mode over dark oceans significantly improves the CO2 information retrieved. The aerosol type and profile are more important than the aerosol optical depth, and underestimation of aerosol plume height will introduce a bias of 1.5 ppm in XCO2. The systematic errors due to radiometric calibration are also estimated using a forward model simulation approach.展开更多
A high-accuracy surface modeling （HASM） method based on the fimdamental theorem of surfaces, is developed to simulate XCO2 surfaces using the GOSAT retrieval XCO2 data. Two tests are designed to investigate the simu...A high-accuracy surface modeling （HASM） method based on the fimdamental theorem of surfaces, is developed to simulate XCO2 surfaces using the GOSAT retrieval XCO2 data. Two tests are designed to investigate the simulation accuracy. The first test divides the existing satellite retrieval XCO2 data into training points and testing points, and simulates the XCO2 surface using the training points while computing the simulation error using the testing points. The absolute mean error （MAE） of the testing points is 1.189 ppmv, and the corresponding values of the comparison methods, Ordinary Kriging, IDW, and Spline are 1.203, 1.301, and 1.355 ppmv, respectively. The second test simulates the XCO2 surface using all the satellite retrieval points and uses the TCCON （Total Carbon Column Observing Network） site observation values as the ture values. For the six typical TCCON sites, the HASM simulation MAE is 1.688 ppmv, and the satellite retrieval MAE at the same sites is 2.147 ppmv. These results indicate that HASM can successfully simulate XCO2 surfaces based on satellite retrieval data.展开更多
Spatiotemporal patterns of column-averaged dry air mole fraction of CO2(XCO2)have not been well characterized on a regional scale due to limitations in data availability and precision.This paper addresses these issues...Spatiotemporal patterns of column-averaged dry air mole fraction of CO2(XCO2)have not been well characterized on a regional scale due to limitations in data availability and precision.This paper addresses these issues by examining such patterns in China using the long-term mapping XCO2 dataset(2009-2016)derived from the Greenhouse gases Observing SATellite(GOSAT).XCO2 simulations are also constructed using the high-resolution nested-grid GEOS-Chem model.The following results are found:Firstly,the correlation coefficient between the anthropogenic emissions and XCO2 spatial distribution is nearly zero in summer but up to 0.32 in autumn.Secondly,on average,XCO2 increases by 2.08 ppm every year from2010 to 2015,with a sharp increase of 2.6 ppm in 2013.Lastly,in the analysis of three typical regions,the GOSAT XCO2 time series is inbetter agreement with the GEOS-Chem simulation of XCO2 in the Taklimakan Desert region(the least difference with bias 0.65±0.78 ppm),compared with the northern urban agglomerationregion(-1.3±1.2 ppm)and the northeastern forest region(-1.4±1.4 ppm).The results are likely attributable to uncertainty in both the satellite-retrieved XCO2 data and the model simulation data.展开更多
文摘Model-Based Development has become an industry wide standard paradigm.As an open source alternative,Scilab/Xcos is being widely employed as a hybrid dynamic systems modeling tool.With the increasing efficiency in implementation using graphical model development and code generation,the modeling and simulation community is struggling with assuring quality as well as maintainability and extendibility.Refactoring is defined as an evolutionary modernization activity where,most of the time,the structure of the artifact is changed to alter its quality characteristics,while keeping its behavior unchanged.It has been widely established as a technique for textual programming languages to improve the code structure and quality.While refactoring is also regarded as one of the key practices of model engineering,the methodologies and approaches for model refactoring are still under development.Architecture-Driven Modernization(ADM)has been introduced by the software engineering community as a model-based approach to software modernization,in which the implicit information that lies in software artifacts is extracted to models and model transformations are applied for modernization tasks.Regarding refactoring as a low level modernization task,the practices from ADM are adaptable.Accordingly,this paper proposes a model-based approach for model refactoring in order to come up with more efficient and effective model refactoring methodology that is accessible and extendable by modelers.Like other graphical modeling tools,Scilab/Xcos also possesses a formalized model specification conforming to its implicit metamodel.Rather than proposing another metamodel for knowledge extraction,this pragmatic approach proposes to conduct in place model-to-model transformations for refactoring employing the Scilab/Xcos model specification.To construct a structured model-based approach,the implicit Scilab/Xcos metamodel is explicitly presented utilizing ECORE as a meta-metamodel.Then a practical model transformation approach is established based on Scilab scripting.A Scilab toolset is provided to the modeler for in-place model-to-model transformations.Using a sample case study,it is demonstrated that proposed model transformation functions in Scilab provide a valuable refactoring tool.
文摘Prior to hardware implementation, simulation is an important step in the study of systems such as Direct Sequence Code Division Multiple Access (DS-CDMA). A useful technique is presented, allowing to model and simulate Linear Feedback Shift Register (LFSR) for CDMA. It uses the Scilab package and its modeling tool for dynamical systems Xcos. PN-Generators are designed for the quadrature-phase modulation and the Gold Code Generator for Global Positioning System (GPS). This study gives a great flexibility in the conception of LFSR and the analysis of Maximum Length Sequences (MLS) used by spread spectrum systems. Interesting results have been obtained, which allow the verification of generated sequences and their exploitation by signal processing tools.
基金supported by grants from the National Key Research and Development Program of China(Grant No.2017YFB0504000)National Natural Science Foundation of China(Grant No.41875043)+2 种基金the Strategic Priority Research 275 Program of the Chinese Academy of Sciences(Grant No.XDA17010102)External Cooperation Program of the Chinese Academy of Science(Grant No.GJHZ1802)Youth Innovation Promotion Association,CAS.
文摘Measurements of column-averaged dry-air mole fractions of carbon dioxide and carbon monoxide,CO_(2)(XCO_(2))and CO(XCO),were performed throughout 2019 at an urban site in Beijing using a compact Fourier Transform Spectrometer(FTS)EM27/SUN.This data set is used to assess the characteristics of combustion-related CO_(2)emissions of urban Beijing by analyzing the correlated daily anomalies of XCO and XCO_(2)(e.g.,ΔXCO andΔXCO_(2)).The EM27/SUN measurements were calibrated to a 125HR-FTS at the Xianghe station by an extra EM27/SUN instrument transferred between two sites.The ratio ofΔXCO overΔXCO_(2)(ΔXCO:ΔXCO_(2))is used to estimate the combustion efficiency in the Beijing region.A high correlation coefficient(0.86)betweenΔXCO andΔXCO_(2)is observed.The CO:CO_(2)emission ratio estimated from inventories is higher than the observedΔXCO:ΔXCO_(2)(10.46±0.11 ppb ppm^(−1))by 42.54%-101.15%,indicating an underestimation in combustion efficiency in the inventories.DailyΔXCO:ΔXCO_(2)are influenced by transportation governed by weather conditions,except for days in summer when the correlation is low due to the terrestrial biotic activity.By convolving the column footprint[ppm(μmol m-2 s-1)-1]generated by the Weather Research and Forecasting-X-Stochastic Time-Inverted Lagrangian Transport models(WRF-X-STILT)with two fossil-fuel emission inventories(the Multi-resolution Emission Inventory for China(MEIC)and the Peking University(PKU)inventory),the observed enhancements of CO_(2)and CO were used to evaluate the regional emissions.The CO_(2)emissions appear to be underestimated by 11%and 49%for the MEIC and PKU inventories,respectively,while CO emissions were overestimated by MEIC(30%)and PKU(35%)in the Beijing area.
基金supported by the Foundation of Science & Technology Department of Henan Province (082102230035)
文摘Crystallization behaviors of Ce60Al15Fe5+xCo20-x(x=0,5,10) bulk metallic glasses(BMGs) were studied by means of differential scanning calorimeter(DSC) and X-ray diffraction(XRD).The crystallization processes of different samples were simulated by JMA equation.Experimental results demonstrated that incubation and crystallization time increased with decreasing isothermal temperature for the same sample.The crystallization mechanism of CeAlFeCo BMGs was discussed.
基金supported by the National Basic Research Development Program of China (Grant no.2011CB952001)
文摘We analyze sea ice changes from eight different earth system models that have conducted experiment abrupt4xCO2 of the Coupled Model Intercomparison Project Phase 5 （CMIP5）. In response to abrupt quadrupling of CO2 from preindustrial levels, Arctic temperatures dramatically rise by about 10℃--16℃ in winter and the seasonal sea ice cycle and sea ice concentration are significantly changed compared with the pre-industrial control simulations （piControl）. Changes of Arctic sea ice concentration are spatially correlated with temperature patterns in all seasons and highest in autumn. Changes in sea ice are associated with changes in atmospheric circulation patterns at heights up to the jet stream. While the pattern of sea level pressure changes is generally similar to the surface air temperature change pattern, the wintertime 500 hPa circulation displays a positive Pacific North America （PNA） anomaly under abrupt4xCO2-piControl. This large scale teleconnection may contribute to, or feedback on, the simulated sea ice cover change and is associated with an intensification of the jet stream over East Asia and the north Pacific in winter.
基金supported by the Strategic Priority Research Program- Climate Change: Carbon Budget and Relevant Issues (Grant No. XDA05040200)the National High-tech Research and Development Program of China (Grant No. 2011AA12A104)
文摘We present a study on the retrieval sensitivity of the column-averaged dry-air mole fraction of CO2(XCO2) for the Chinese carbon dioxide observation satellite(TanSat) with a full physical forward model and the optimal estimation technique. The forward model is based on the vector linearized discrete ordinate radiative transfer model(VLIDORT) and considers surface reflectance, gas absorption, and the scattering of air molecules, aerosol particles, and cloud particles. XCO2 retrieval errors from synthetic TanSat measurements show solar zenith angle(SZA), albedo dependence with values varying from 0.3 to 1 ppm for bright land surface in nadir mode and 2 to 8 ppm for dark surfaces like snow. The use of glint mode over dark oceans significantly improves the CO2 information retrieved. The aerosol type and profile are more important than the aerosol optical depth, and underestimation of aerosol plume height will introduce a bias of 1.5 ppm in XCO2. The systematic errors due to radiometric calibration are also estimated using a forward model simulation approach.
基金the members of the GOSAT Project (JAXA,NIES and Ministry of the Environment,Japan) for providing GOSAT Level 2 data productssupported by the National High-Tech R&D Program of the Ministry of Science and Technology of China(Grant Nos.2013AA122003,2011AA12A104-3)+5 种基金the Research Projects of Chuzhou University(Grant No.2015QD08)the Key Program of National Natural Science Foundation of China(Grant No. 91325204)the National Fundamental R&D Program of the Ministry of Science and Technology of China(Grant No.2013FY111600-4)the European Commission's Seventh Framework Programme "PANDA "(Grant No. FP7-SPACE-2013-1)the Public Industry-Specific Fund for Meteorology (Grant No.GYHY201106045)the 4th and 5th GOSAT/TANSO Joint Research Project
文摘A high-accuracy surface modeling （HASM） method based on the fimdamental theorem of surfaces, is developed to simulate XCO2 surfaces using the GOSAT retrieval XCO2 data. Two tests are designed to investigate the simulation accuracy. The first test divides the existing satellite retrieval XCO2 data into training points and testing points, and simulates the XCO2 surface using the training points while computing the simulation error using the testing points. The absolute mean error （MAE） of the testing points is 1.189 ppmv, and the corresponding values of the comparison methods, Ordinary Kriging, IDW, and Spline are 1.203, 1.301, and 1.355 ppmv, respectively. The second test simulates the XCO2 surface using all the satellite retrieval points and uses the TCCON （Total Carbon Column Observing Network） site observation values as the ture values. For the six typical TCCON sites, the HASM simulation MAE is 1.688 ppmv, and the satellite retrieval MAE at the same sites is 2.147 ppmv. These results indicate that HASM can successfully simulate XCO2 surfaces based on satellite retrieval data.
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0600303)the Key Deployment Projects of the Chinese Academy of Sciences (Grant No. ZDRWZS-2019-1-3)
文摘Spatiotemporal patterns of column-averaged dry air mole fraction of CO2(XCO2)have not been well characterized on a regional scale due to limitations in data availability and precision.This paper addresses these issues by examining such patterns in China using the long-term mapping XCO2 dataset(2009-2016)derived from the Greenhouse gases Observing SATellite(GOSAT).XCO2 simulations are also constructed using the high-resolution nested-grid GEOS-Chem model.The following results are found:Firstly,the correlation coefficient between the anthropogenic emissions and XCO2 spatial distribution is nearly zero in summer but up to 0.32 in autumn.Secondly,on average,XCO2 increases by 2.08 ppm every year from2010 to 2015,with a sharp increase of 2.6 ppm in 2013.Lastly,in the analysis of three typical regions,the GOSAT XCO2 time series is inbetter agreement with the GEOS-Chem simulation of XCO2 in the Taklimakan Desert region(the least difference with bias 0.65±0.78 ppm),compared with the northern urban agglomerationregion(-1.3±1.2 ppm)and the northeastern forest region(-1.4±1.4 ppm).The results are likely attributable to uncertainty in both the satellite-retrieved XCO2 data and the model simulation data.
