【目的】检验SCOPE(Soil Canopy Observation of Photosynthesis and Energy fluxes)模型用于模拟樟子松人工林的日光诱导叶绿素荧光(sun-induced chlorophyll fluorescence,SIF)和植被总初级生产力(gross primary productivity,GPP)动...【目的】检验SCOPE(Soil Canopy Observation of Photosynthesis and Energy fluxes)模型用于模拟樟子松人工林的日光诱导叶绿素荧光(sun-induced chlorophyll fluorescence,SIF)和植被总初级生产力(gross primary productivity,GPP)动态变化的可能性。【方法】对科尔沁沙地南缘樟子松人工林,基于样地SIF、GPP及气象协同观测数据,利用SCOPE模型模拟SIF与GPP的日变化与季节变化,评估了SCOPE模型在典型晴天、典型多云日、整个观测期的模拟效果。【结果】结果显示,利用气象观测数据及冠层参数(入射短波辐射、气温、大气实际水汽压、CO_(2)浓度及叶面积指数),可驱动SCOPE模型模拟樟子松人工林的SIF与GPP。典型晴天日与多云日的SIF模拟值和实测值的R^(2)分别为0.42与0.52,RMSE分别为0.19与0.18 W·m^(-2)·μm^(-1)·sr^(-1);GPP模拟值和观测值的R^(2)分别为0.78与0.89,RMSE分别为1.87与2.57μmol·m^(-2)·s^(-1)。在季节尺度上,SIF和GPP模拟值和观测值的R^(2)分别为0.50、0.72,RMSE分别为0.19 W·m^(-2)·μm^(-1)·sr^(-1)和2.64μmol·m^(-2)·s^(-1)。在整个观测期,多云日的SIF(R^(2)=0.31,RMSE=0.22 W·m^(-2)·μm^(-1)·sr^(-1))与GPP(R^(2)=0.80,RMSE=2.42μmol·m^(-2)·s^(-1))的模拟效果优于晴天日(SIF:R^(2)=0.30,RMSE=0.26 W·m^(-2)·μm^(-1)·sr^(-1),GPP:R^(2)=0.64,RMSE=3.64μmol·m^(-2)·s^(-1))。SIF模拟值总体高于观测值,当SIF强度较低时易对SIF高估,反之则易低估。GPP的模拟精度较高,模型对较低与较高GPP有所低估,对中间值有所高估。【结论】SCOPE模型可用于日尺度与季节尺度的SIF与GPP模拟,且多云日的模拟精度更高。SCOPE模型对樟子松人工林的GPP模拟结果优于SIF,推测SIF模拟精度较低的原因可能是模型对SIF的模拟是基于阔叶植物的辐射传输过程。未来应发展针对针叶植物的SIF辐射传输模型,为针叶林的辐射传输与荧光遥感监测提供模型基础。展开更多
Data is a key asset for digital platforms,and mergers and acquisitions(M&As)are an important way for platform enterprises to acquire it.The types of data obtained from intra-industry and cross-sector M&As diff...Data is a key asset for digital platforms,and mergers and acquisitions(M&As)are an important way for platform enterprises to acquire it.The types of data obtained from intra-industry and cross-sector M&As differ,as does the extent to which they interact within or between platforms.The impact of such data on corporate market performance is an important question to consider when selecting strategies for digital platform M&As.Based on our research on advertising-driven platforms,we developed a two-stage Hotelling game model for comparing the market performance effects of intra-industry M&As and cross-sector M&As for digital platforms.We carried out an empirical test using relevant data from advertising-driven digital platforms between 2009 and 2021,as well as a case study on Baidu’s M&A activities.Our research discovered that intra-industry M&As driven by“data economies of scale”and cross-sector M&As driven by“data economies of scope”are both beneficial to the market performance of platform enterprises.Intra-industry M&As have a more significant positive effect on the market performance of platform enterprises because the same types of data are easier to integrate and develop the“network effect of data scale”.From a data factor perspective,this paper reveals the inherent economic logic by which different types of M&As influence the market performance of digital platforms,as well as policymaking recommendations for all digital platforms to select M&A strategies based on data scale,data scope,and the network effect of data.展开更多
With the chief aim to list a brief description on business writing,such thesis mainly deal with the content and skill in this field.Business writing locates a role in business world which cannot be ignored by any othe...With the chief aim to list a brief description on business writing,such thesis mainly deal with the content and skill in this field.Business writing locates a role in business world which cannot be ignored by any other means.In case a successful business manager desires to be achievable,the business letters ought to be treated seriously.Some popular forms of writing are also included and simply illustrated in lieu the basic requirement meeting from some of those readers.Obviously we learners and teachers are hopefully required to set great store by the mentioned scope of utilization.展开更多
基金supported by the National Natural Science Foundation of China“Research on Cross-sector Competition Effect and Regulatory Policy of Digital Platforms Based on Inter-platform Network Externalities”(Grant No.72103085).
文摘Data is a key asset for digital platforms,and mergers and acquisitions(M&As)are an important way for platform enterprises to acquire it.The types of data obtained from intra-industry and cross-sector M&As differ,as does the extent to which they interact within or between platforms.The impact of such data on corporate market performance is an important question to consider when selecting strategies for digital platform M&As.Based on our research on advertising-driven platforms,we developed a two-stage Hotelling game model for comparing the market performance effects of intra-industry M&As and cross-sector M&As for digital platforms.We carried out an empirical test using relevant data from advertising-driven digital platforms between 2009 and 2021,as well as a case study on Baidu’s M&A activities.Our research discovered that intra-industry M&As driven by“data economies of scale”and cross-sector M&As driven by“data economies of scope”are both beneficial to the market performance of platform enterprises.Intra-industry M&As have a more significant positive effect on the market performance of platform enterprises because the same types of data are easier to integrate and develop the“network effect of data scale”.From a data factor perspective,this paper reveals the inherent economic logic by which different types of M&As influence the market performance of digital platforms,as well as policymaking recommendations for all digital platforms to select M&A strategies based on data scale,data scope,and the network effect of data.
文摘With the chief aim to list a brief description on business writing,such thesis mainly deal with the content and skill in this field.Business writing locates a role in business world which cannot be ignored by any other means.In case a successful business manager desires to be achievable,the business letters ought to be treated seriously.Some popular forms of writing are also included and simply illustrated in lieu the basic requirement meeting from some of those readers.Obviously we learners and teachers are hopefully required to set great store by the mentioned scope of utilization.
