水泵与水轮机空化状态监测与诊断的研究进展

影响水泵与水轮机使用寿命与性能的主要问题是空化空蚀现象，在现场监测与分析水泵与水轮机的空化状态是空化空蚀研究的重要领域，根据国外对空化监测与分析的最新研究成果和背景噪声的处理手段。介绍了空化监测与分析的新方法，肉加速度计与声压计测得的空化信号时域图，功率谱图和归一化谱图中，反映了出空化发生的特征，信号处理方法的意义。     

Past, present and future criteria to breed crops for water-limited environments in West Africa

Asia's Green Revolution of the 1960s and 1970s has largely bypassed West Africa, and “modern” (high-yielding, input responsive) germplasm for staple crops has found comparatively little adoption, except for systems that are have good access to markets and sufficient water resources. It is unlikely, however, that breeding objectives conserving traditional crop characteristics as found in extensive systems would have been more successful. The authors identify systems caught in the agricultural transition from subsistence to intensified, market-oriented production as the most important target for crop improvement, and provide examples of new breeding objectives for cowpea, sorghum and upland rice. In each of these cases, breeders, with the help of physiologists, have developed innovative plant-type concepts that combine improved yield potential and input responsiveness with specific traditional crop characteristics that remain essential during the agricultural transition. In the case of cowpea, dual-purpose varieties were developed that produce a good grain yield due to an erect plant habit, then produce new leaves enabling a second harvest of green foliage. For upland rice systems that are limited by labour (mainly needed to control weeds that abound due to shortened fallow periods), a weed competitive plant type was developed from Oryza sativa × Oryza glaberrima crosses. Lastly, sorghum breeders who had previously deselected photoperiod sensitivity are now re-inserting sensitivity into plants having “modern” architecture, in order to allow for flexible sowing dates while maintaining an agro-ecologically optimal time of flowering near the end of the wet season. The ecophysiological basis of these plant types, their place in current and future cropping systems, as well as the problem of under-funding for their realisation, are discussed.     

Evaluation of the RZWQM-CERES-Maize hybrid model for maize production

The root zone water quality model (RZWQM) was developed primarily for water quality research with a generic plant growth module primarily serving as a sink for plant nitrogen and water uptake. In this study, we coupled the CERES-Maize Version 3.5 crop growth model with RZWQM to provide RZWQM users with the option for selecting a more comprehensive plant growth model. In the hybrid model, RZWQM supplied CERES with daily soil water and nitrogen contents, soil temperature, and potential evapotranspiration, in addition to daily weather data. CERES-Maize supplied RZWQM with daily water and nitrogen uptake, and other plant growth variables (e.g., root distribution and leaf area index). The RZWQM-CERES hybrid model was evaluated with two well-documented experimental datasets distributed with DSSAT (Decision Support System for Agrotechnology Transfer) Version 3.5, which had various nitrogen and irrigation treatments. Simulation results were compared to the original DSSAT-CERES-Maize model. Both models used the same plant cultivar coefficients and the same soil parameters as distributed with DSSAT Version 3.5. The hybrid model provided similar maize prediction in terms of yield, biomass and leaf area index, as the DSSAT-CERES model when the same soil and crop parameters were used. No overall differences were found between the two models based on the paired t test, suggesting successful coupling of the two models. The hybrid model offers RZWQM users access to a rigorous new plant growth model and provides CERES-Maize users with a tool to address soil and water quality issues under different cropping systems.     

棉秆粉碎收获机的设计

利用旋转甩刀的切割及冲击作用对棉秆进行粉碎，并利用甩刀高速旋转产生的惯性和气流对粉碎的棉秆进行抛送。在田间试验的基础上，通过理论探讨，对棉秆粉碎收获机的基本原理、主要部件及技术参数，尤其是甩刀转速进行分析、设计，设计了与中型拖拉机配套的棉秆粉碎收获机。     

湖南农业运输机械事故灰色关联分析

利用灰色系统理论方法,对湖南省1997～2002年的农业运输机械事故的影响因素进行了系统分析,分析计算结果是:拖拉机拥有量与事故起数的关联度最大;事故起数关联度最大的是机械故障;驾车3年以上的驾驶员是事故发生的高危人群。     

高原环境对拖拉机、农用运输车安全性能的影响及对策

着重从青藏高原的地理、气候、道路等环境特点,分析高原环境对拖拉机、农用运输车安全生产影响的因素,提出预防措施,以确保安全生产。     

农业机械虚拟试验交互控制系统

设计了农业机械虚拟试验系统,建立了田间工况模拟与虚拟交互控制试验平台.根据耕作区域的数字地图及农田作物图像信息,设计农业机械虚拟试验场,实现人和农业机械在虚拟环境内的漫游.建立四自由度模拟试验台,实现对拖拉机在田间行走时姿态的模拟仿真.从虚拟场景中提取作物行的位置信息,根据这些信息给出控制信号,进行拖拉机行驶速度、方向和平衡控制,使拖拉机沿作物行行驶.试验表明,横滚角最大偏差为0.34°,偏航角最大偏差为0.51°,高程最大偏差为2.5 mm,行走速度最大偏差为0.12 km/h.实体样机和虚拟样机有较好的一致性.     

一种小型多功能田间管理机的设计

为降低小地块耕作的劳动强度、提高劳动效率,在充分吸收大中型农业机械设备技术的基础上,开发出小型多功能田间管理机。该机是一种特色农业多功能田间管理机械,通过更换不同的工作部件,可以完成田间旋耕整地、播种、施肥、培土、田间施药、施叶面肥、果树喷药等多种作业,还能用于田间运输。田间试验示范结果表明,该机工作效率是人工作业的10倍左右,每台机器可管理1 hm2以上的庄稼,是玉米、花生、棉花等作物田间管理的机械化作业工具。     

Agricultural practice changes with cultivating genetically modified herbicide-tolerant oilseed rape

To facilitate weed suppression, oilseed rape or canola (Brassica napus) has been genetically modified (GM) over the last two decades to incorporate herbicide tolerance (HT). The introduction of oilseed rape in commercial agriculture raises concerns about potential adverse agronomic and environmental effects linked to both the genetic modification and altered agricultural practice. How will this new crop modify the existing cropping practice? What are the potential agro-environmental implications of its introduction? This paper analyses and schematises recorded and conceivable agricultural practice changes with GMHT oilseed rape introduction and its likely agro-environmental effects. It develops a conceptual systematics of influencing factors, subsequent practice changes and likely agro-environmental effects. The results can be used to design the mandatory monitoring of adverse GM crop effects.     

农业物料力学试验测控系统设计

介绍了基于计算机的农业物料力学试验测控系统的组成和测控软件。应用结果表明，该系统工作可靠，虚拟仪器面板操作简便，实现了农业物为力学试验数据采集及试验过程自动化。