Overall level of export fluctuations of the export-oriented countries with rising export volume partly stem from the market failure caused by free choice of export enterprises,some government intervention thus may be ...Overall level of export fluctuations of the export-oriented countries with rising export volume partly stem from the market failure caused by free choice of export enterprises,some government intervention thus may be necessary.To reduce the level of fluctuations of the export growth rates in these countries,this paper,taking the significant differences of the exports among various markets into account and thus using a new index named relative variance to measure the export volatility risks,proposes a model of merchandise market portfolio,a modified version of Markowitz model,available to provide explicit guidelines for the firms,the industries and even the whole country to optimize the structure of their export markets.An application of this model to the case of China’s apple is then discussed.The results show that the market share of China’s apple in 7 sub-markets should be redistributed drastically.展开更多
There is a great uncertainty in generation and formation of non-point source(NPS)pollutants,which leads to difficulties in the investigation of monitoring and control.However,accurate calculation of these pollutant lo...There is a great uncertainty in generation and formation of non-point source(NPS)pollutants,which leads to difficulties in the investigation of monitoring and control.However,accurate calculation of these pollutant loads is closely correlated to control NPS pollutants in agriculture.In addition,the relationships between pollutant load and human activity and physiographic factor remain elusive.In this study,a modified model with the whole process of agricultural NPS pollutant migration was established by introducing factors including rainfall driving,terrain impact,runoff index,leaching index and landscape intercept index for the load calculation.Partial least squares path modeling was applied to explore the interactions between these factors.The simulation results indicated that the average total nitrogen(TN)load intensity was 0.57 t km-2 and the average total phosphorus(TP)load intensity was 0.01 t km-2in Chengdu Plain.The critical effects identified in this study could provide useful guidance to NPS pollution control.These findings further our understanding of the NPS pollution control in agriculture and the formulation of sustainable preventive measures.展开更多
基金the project(2018GWQNCX038)for innovative talents in regular universities of the Department of education of Guangdong Province in 2019.
文摘Overall level of export fluctuations of the export-oriented countries with rising export volume partly stem from the market failure caused by free choice of export enterprises,some government intervention thus may be necessary.To reduce the level of fluctuations of the export growth rates in these countries,this paper,taking the significant differences of the exports among various markets into account and thus using a new index named relative variance to measure the export volatility risks,proposes a model of merchandise market portfolio,a modified version of Markowitz model,available to provide explicit guidelines for the firms,the industries and even the whole country to optimize the structure of their export markets.An application of this model to the case of China’s apple is then discussed.The results show that the market share of China’s apple in 7 sub-markets should be redistributed drastically.
基金Key Research and Development Program of Hubei Province,No.2020BCA073Independent Innovation Research Program of Changjiang Institute of Survey,Planning,Design and Research Co.,Ltd.,No.CX2019Z05。
文摘There is a great uncertainty in generation and formation of non-point source(NPS)pollutants,which leads to difficulties in the investigation of monitoring and control.However,accurate calculation of these pollutant loads is closely correlated to control NPS pollutants in agriculture.In addition,the relationships between pollutant load and human activity and physiographic factor remain elusive.In this study,a modified model with the whole process of agricultural NPS pollutant migration was established by introducing factors including rainfall driving,terrain impact,runoff index,leaching index and landscape intercept index for the load calculation.Partial least squares path modeling was applied to explore the interactions between these factors.The simulation results indicated that the average total nitrogen(TN)load intensity was 0.57 t km-2 and the average total phosphorus(TP)load intensity was 0.01 t km-2in Chengdu Plain.The critical effects identified in this study could provide useful guidance to NPS pollution control.These findings further our understanding of the NPS pollution control in agriculture and the formulation of sustainable preventive measures.
