天空地数字农业管理系统框架设计与构建建议

数据正在成为基础性战略资源。构建以天空地大数据为关键要素的数字农业管理系统,对于建设数字中国、推进农业高质量发展、抢占全球农业制高点具有重要意义。本研究围绕农业农村部提出的天空地数字农业管理系统建设任务,从农业信息技术学科出发,首先给出了天空地数字农业的科学内涵,阐述了其与传统数字农业的异同点,理清了天空地数字农业管理系统在资源调查、生产调度、灾害监测、市场预警、决策服务的五大核心功能;其次,重点阐述了天空地数字农业管理系统的关键任务,即一个观测体系(天空地一体化的数字农业观测体系)、四个数字化(农业资源权属、生产过程、灾害监测和市场预警)、一个管理平台(农业生产、加工、经营、管理、服务等全产业链的天空地数字农业管理平台);然后,明确提出了天空地数字农业管理系统在标准规范研制、关键技术与装备研发、系统集成与平台开发三方面的科技创新重点任务;最后,针对天空地数字农业管理系统建设的复杂性和系统性,从规划设计、科技创新、资源共享、多方参与、应用领域拓展等方面提出了发展建议。

基于遥感数据的大尺度区域水田空间格局及生态服务价值变化分析

受经济和气候驱动,长江经济带水田空间格局发生了显著变化,影响区域粮食安全与生态安全。本研究基于1990-2015年土地利用遥感监测数据,利用GIS的空间分析功能,探究长江经济带水田空间格局动态变化特征,采用当量因子法计算生态系统服务价值(ESV),分析了水田变化的综合影响。结果表明:1) 1990-2015年长江经济带水田规模持续缩减,共减少了17390km^2,减幅呈增长态势具有显著地域差异,长江中上游与下游的水田减幅相差约为9.56%。其中下游减幅较大,水田占区域比例随之降低,中上游恰好相反。2)由于经济建设及水产养殖的发展,水田主要转化为建设用地和水系,水田主要由水系、旱地和湿地等转化而来。长江三角洲城市群、长江中游及成渝城市群的水田变化最为剧烈,建设用地侵占水田扩张的现象分布广泛,水田转为水系主要在两湖平原局部地区。3)水田与其他生态系统的转化对ESV是正影响,水田转为水系对此贡献最大,其转化规模决定了不同时期ESV净增量的大小,水系转化为水田损失的价值最多,建设用地侵占水田次之。不同市域的水田变化情况不一致,因此ESV增减情况具有明显差异。4)生态系统服务中水文调节、水资源供给增强的同时,食物生产、气体调节受到严重损害,与水资源规模扩大和水田资源大量流失有直接关系。研究结果有助于揭示长江流域水田的时空变化过程及其对各项生态系统服务的影响,可为区域土地利用规划、农业政策与生态可持续发展提供理论支持。

Study on the Agricultural Fuel Consumption Subsidy Policy for Wheat Straw Low Stubble——Taking the Investigation of Wheat Combine Harvester as an Example in Xushui District of Hebei Province

With the improvement of agricultural mechanization equipment levels, the mechanized wheat harvesting level has been above 80% and the rate of wheat straw returned has increased significantly in the main wheat production of wheat of northern countryside in China. Chinese government popularized the beneficial agronomic measures in the process of wheat straw returned field by mechanization. The agronomic measure was reducing the wheat straw stubble height(WSSH) not more than 20 cm.However, local government didn't apply and disseminate the measure, because in practice the cost of fuel consumption was high, and the operation time of harvesting was longer than ever. The machinery operators and farmers needed to support extra fuel cost and time if they took government's advice. In fact, the objective subsidy policy of fuel cost on reducing WSSH was not been formulated by all levels of government. Therefore, the set of agronomic measure couldn't be popularized in main wheat production area of North China. Our research addressed to master the changing feature of fuel cost and mechanical efficiency,seeking suitable subsidy standard, providing some useful and constructive suggestions to improve subsidy policy of fuel consumption cost for national government department. The study carried out the tracking experiments of the operation efficiency and fuel costs of farm harvester in the situation of different WSSH in 2010 in Xushui District of Hebei Province. In conclusion, the operation time of harvesting decline and machinery fuel consumption cost increased along with the decreasing of WSSH. First for the older harvester, the operation efficiency would decline by 18.7% when the WSSH changed from 20 cm to 10 cm, the cost would increase 4.7%, exact cost was 152.2CNY per hectare. For the new harvester, the operation efficiency would decline by 39.9% when the WSSH changed from 20 cm to 15 cm, the cost would increase 4.6%, exact cost was 368.4CNY per hectare. We provided about 375 CNY per hectare to the mechanical operators and farmer who attended this project, and they were willing to accept the subsidies. We also put forwards some policy suggestions on promoting agronomic measures of reducing WSSH including strengthen the construction of agricultural machinery service system, practise a special fuel consumption subsidies of agricultural machinery and open up new paths for combine sales and circulation.

Sodium Superionic Conductors(NASICONs)as Cathode Materials for Sodium‑Ion Batteries

Sodium-ion batteries(SIBs)have developed rapidly owing to the high natural abundance,wide distribution,and low cost of sodium.Among the various materials used in SIBs,sodium superion conductor(NASICON)-based electrode materials with remarkable structural stability and high ionic conductivity are one of the most promising candidates for sodium storage electrodes.Nevertheless,the relatively low electronic conductivity of these materials makes them display poor electrochemical performance,significantly limiting their practical application.In recent years,the strategies of enhancing the inherent conductivity of NASICON-based cathode materials have been extensively studied through coating the active material with a conductive carbon layer,reducing the size of the cathode material,combining the cathode material with various carbon materials,and doping elements in the bulk phase.In this paper,we review the recent progress in the development of NASICON-based cathode materials for SIBs in terms of their synthesis,characterization,functional mechanisms,and performance validation/optimization.The advantages and disadvantages of such SIB cathode materials are analyzed,and the relationship between electrode structures and electrochemical performance as well as the strategies for enhancing their electrical conductivity and structural stability is highlighted.Some technical challenges of NASICON-based cathode materials with respect to SIB performance are analyzed,and several future research directions are also proposed for overcoming the challenges toward practical applications.