Construction of Regional Grain Industry Chain and Supply Chain in Yunnan Province

As a southwestern border province of China,Yunnan is featured by the geographical advantage of proximity to the Indo-China Peninsula which is known as World Rice Warehouse,and its capital and technology are ahead of the neighboring countries of China.Therefore,to enhance its support capability in consolidating and improving the national food security strategy,Yunnan should further develop its comparative advantages by building the regional food industry chain and supply chain depending on the province's grain system of production,processing,storage and transportation,as well as its agricultural economic and trade cooperation platforms and channels with the neighboring countries of China.In this study,comparative analysis and related methods were used to systematically analyze the scale of grain production in Yunnan,the proportion of its grain production to the national total amount,the transition of its grain variety structure and the characteristics of its food security system,as well as the grain export trade of the 6 countries in the Indo-China Peninsula from 2010 to 2019.Then,the problems in grain production in Yunnan were clarified,such as the decrease of grain ration production capacity,the decline of comparative benefits of grain production and the insufficient support for agricultural"going global"strategy.Finally,a series of countermeasures were put forward,including further implementing the strategy of"reserving grain in land and technology"to increase Yunnan's production capacity of grain,focusing on agricultural products storage and transportation system to improve the ability to obtain grain from abroad,expanding the border processing and logistics industry,optimizing the policy of agricultural products'import and export,and etc.

The Construction and Competitiveness of Operation Model of Agricultural Industrial Cluster

Through reviewing the viewpoints of former scholars, the connotation and features of supply chain of agricultural industrial cluster are introduced. The agricultural industrial cluster model constituted by core network and supporting network is constructed. Three operation models of this kind of supply chain is described: the model takes wholesale market of agricultural products as the core; the model take pillar industries of agricultural industrialization as core; model takes the chains of retail enterprises as core. The competitiveness of agricultural industrial cluster is researched. The research assumes that the competiveness of supply chain of agricultural industrial cluster is mainly represented to make the agricultural industrial cluster to acquire more capabilities in terms of innovation and knowledge sharing capability, resource allocation capability, agile market adaptability and distinct value creation capability.

Industrial frequency single-phase AC traction power supply system for urban rail transit and its key technologies

To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of a main substation （MSS） and cable traction network （CTN）. The MSS includes a single-phase main traction transformer and a negative-se- quence compensation device, while the CTN includes double-core cables, traction transformers, overhead catenary system, rails, etc. Several key techniques for the proposed system were put forward and discussed, which can be summarized as （1） the power supply principle, equivalent circuit and transmission ability of the CTN, the cable-catenary matching technique, and the selection of catenary voltage level; （2） the segmentation technology and status identification method for traction power supply network, distributed and centralized protection schemes, etc.; （3） a power supply scheme for single-line MSS and a power supply scheme of MSS shared by two or more lines. The proposed industrial frequency single-phase AC traction power supply system shows an excellent technical performance, good economy, and high reliability, hence provides a new alternative for metro and urban rail transit power supply systems.