三堡排涝工程船闸引航道防护研究

杭州市三堡排涝工程主要排水口位于三堡船闸引航道内,排涝对船闸运行及引航道防护存在较大影响.采用平面二维潮流数学模型和物理模型,对各排涝运行工况进行了模拟,通过对该引航道的防冲性能、防护投资、清淤维护、航运影响、施工难易程度等因素的综合分析,提出了防护优化方案.该方案节约了防护工程造价,有效地减少了工程实施及维护对排水口所在船闸正常运行的影响,对研究排涝通道与通航建筑物相结合工程具有参考意义.     

河套灌区套种模式下综合作物系数的试验研究

依据FAO56作物需水量指南提供的作物系数计算方法,分别计算了内蒙古河套灌区磴口试验站小麦套种覆膜玉米、小麦套种未覆膜玉米、小麦套种油料向日葵3种套种模式下的综合单、双值作物系数。结果表明,3种套种模式下的作物在全生育期内均可迎来2次综合需水高峰;共生阶段的作物系数,单值方法高于双值方法的计算结果,而单一作物独立生长阶段,双值方法高于单值方法的计算结果;无论单值计算还是双值计算的套种作物田间综合ET,当单一作物处于独立生长期时差别不大,而2种作物共同生育阶段的差别较大;将3种作物在套种模式下的生育阶段划分的更加详细并分别命名,为套种模式下作物蒸散量提供更准确的计算依据。     

Formalizing agro-ecological engineering for future-oriented land use studies

Agriculture faces an array of interrelated problems that call for development of new and revision of existing cropping systems towards the multiple needs of the 21st century. Agro-ecological engineering approaches aimed at design and exploration of alternative land use systems at various scales may support the identification of appropriate land use options. Engineering approaches are based on mathematical representations of well-founded agro-ecological principles while taking into account available resources and prevailing land-related objectives. The goal of this paper is to contribute to the development of a formalized approach to engineer cropping systems at the land unit level that can be used as building blocks for systematic explorations of land use options at farm or regional scale. The approach for engineering cropping systems at the land unit level consists of three steps: (i) goal-driven design of cropping systems, (ii) quantification of biophysical production targets and (iii) definition of the optimal mix of inputs required to realize production targets. This paper describes the approach and illustrates it with examples from the Sudano-Sahelian zone of Mali. Explicit attention is paid to the required numerical tools and their application to analyze consequences of uncertainty in the performance of engineered cropping systems. Using numerical tools, uncertainty is made explicit with the aim to better manage or reduce it. Identification of uncertainty at the designer's desk allows taking uncertainty into account before applying engineered land use systems in regional model studies or testing such systems in practice. Problems related to the application of numerical tools are discussed, including the future role of agro-ecological engineering as independent discipline within agricultural science.     

Identification of a diverse mini‐core panel of Indian rice germplasm based on genotyping using microsatellite markers

Identification of a small core germplasm set representing the available genetic diversity is essential for its proper evaluation and subsequent utilization in rice improvement programmes. For constituting a small diverse mini‐core panel of Indian rice germplasm, a representative set of 6912 accessions drawn based on their geographic origin from the whole rice germplasm collection available in the National Gene Bank was genotyped using 36 microsatellite markers. Automated fragment analysis of amplicons yielded a total of 435 alleles, with an average 12.4 and range of 3–29 alleles per locus. Polymorphism information content (PIC) ranged from 0.08 (RGNMS190) to 0.86 (RM552) with an average of 0.528. Based on genotyping data, a mini‐core consisting of 98 genotypes was identified. Ninety‐four per cent of the alleles present in the core set were present in the mini‐core. The identified small but diverse panel will be useful for further intensive trait‐specific evaluation and utilization in allele mining.     

The impact of equalisation of basic public health and medical services on the long-term urban settlement intentions of internal migrants in China

Using China Migrants Dynamic Survey Project data from 2012 to 2018, this paper evaluates the causal impact of equalisation of basic public health and medical services on the long-term urban settlement intentions of internal migrants by the difference-in-differences approach. The results reveal that the equalisation of basic public health and medical services has a negative impact on the long-term urban settlement intentions of internal migrants of 4%. Male, middle-aged, and unmarried internal migrants have a much stronger negative response, in terms of long-term urban settlement intentions, to changes in basic public health and medical services. Moreover, more recent internal migrants, those in first-tier cities and those in cities in eastern regions also have a much stronger negative response. Mechanism checks imply that the negative impact on the long-term urban settlement intentions of internal migrants is caused by social integration decline after implementation of equalisation of basic public health and medical services.     

大型排灌工程项目后评价理论及方法

大型排灌工程项目后评价是大型排灌工程项目科学管理的重要环节。根据大型排灌工程的具体特点 ,讨论项目后评价的理论基础和评价方法 ,分析了大型排灌工程项目后评价的特点、内容、基本原则和程序 ,提出了后评价的指标体系及各种指标的计算方法。     

基于自适应模拟退火算法的HEV能量管理优化

基于iSight和ADVISOR联合仿真平台,采用自适应模拟退火算法对混合动力汽车的能量管理策略进行优化,主要对模糊控制策略的隶属度函数进行了优化,从而克服了基于专家经验进行参数选择的弊端.在ADVISOR中对UDDS工况进行了仿真对比.优化结果表明,所设计的模糊控制器和自适应模拟退火算法合理有效,车辆的燃油经济性和排...     

种质资源创新与利用途径分析

近年来我国作物种质资源研究工作得到飞跃发展,现代生物技术与常规技术相结合已成为种质资源创新的途径。介绍作物种质资源利用的传统途径,阐述生物技术在种质资源创新与利用中的应用,并展望种质资源创新与利用的发展趋势。     

Precipitation or water capacity indices? An analysis of the benefits of alternative underlyings for index insurance

Eastern Germany is often hit by drought causing income risk for crop farmers. Index-based risk management instruments could help crop farmers to reduce their farm income risk. Such instruments have some important advantages over damage-based insurance, like e.g. less moral hazard and adverse selection. At the same time they typically have a high level of basis risk. Up to now, mainly precipitation-based weather derivatives have been discussed as an appropriate risk management instrument for farmers in Germany. As a potentially more effective alternative, we propose water capacity-based index insurance. In order to show the benefits of a precipitation-based and water capacity-based index insurance, several contract designs are compared. Using a whole farm risk program planning approach, we show that for an average agricultural producer in Eastern Germany water capacity-based index insurance offers greater benefits than precipitation-based index insurance.     

固原市退耕还林后续产业现状及发展对策探讨

本文通过对固原市退耕还林后续产业现状调查,分析退耕还林后续产业存在的问题,探讨固原市退耕还林后续产业发展对策,力求对固原市退耕还林后续产业发展提供参考。