步行式插秧机共轭凸轮推秧装置的反求设计及仿真

针对步行式插秧机上传统推秧装置存在的推秧结束时间提前或滞后问题,提出了基于共轭凸轮的推秧装置.根据步行式插秧机椭圆齿轮行星系驱动机构及插秧农艺要求构造了推秧杆的运动学曲线,建立了该推秧装置反求模型,并基于Visual Basic 6.0编写了其反求设计及仿真软件,反求得到一组满足农艺要求的较优参数.根据这组参数对该推秧装置进行结构设计,建立了三维模型并进行虚拟样机仿真,结果表明该装置能很好地满足步行式插秧机的作业要求,而且推秧结束时间准确.     

步行式插秧机等径凸轮强制推秧装置反求设计与试验

为解决共轭凸轮推秧装置结构尺寸过大的问题,提出了等径凸轮推秧装置。该推秧装置由等径凸轮控制推秧杆运动。根据推秧杆农艺要求及椭圆齿轮行星系驱动机构构造了推秧杆的理想运动学曲线,建立了该推秧装置的反求模型。基于VB 6.0编写了其反求设计及仿真软件,得到一组满足农艺要求的参数,包括机构参数和等径凸轮廓线。根据这组参数研制了该推秧装置并进行高速录像试验。理论分析及试验结果表明,该推秧装置能够满足推秧杆的农艺要求,且具有比共轭凸轮推秧装置更小巧的结构尺寸。     

水稻插秧机分插机构的动力学分析

以水稻插秧机分插机构为研究对象,进行了运动学和动力学分析,建立了计算机模型,其中包括自动绘制特性曲线子程序。该模型与以往国内外研究的不同之处在于,它模拟了推秧装置在工作过程中对机构的动力学作用。研制了试验台,对2ZT-935型插秧机分插机构曲柄轴受力进行了测试。理论计算和测试结果比较表明:它们基本是吻合的,也验证了推秧装置是机构的主要振动源,在理论分析中是不能忽略的。利用模型建立起来的程序,对该机构生产上可行的改进方案进行了优化计算,并且再次进行试验验证,得到了最佳改进方案。该模型和试验台适用于各种机型的分插机构的理论分析和试验。     

分插机构在我国现有插秧机上的应用

分插机构是插秧机不可缺少的重要机构。结合国内外５种有代表性的机型，对比分析了我国现有插秧机分插机的机构的结构特点，性能及优缺点，得分插机构的设计，采用带有定时脱秧装置分置式曲柄连杆机构，弹簧推秧，凸轮提升回位的推秧了好，适合国情。     

旋转式水稻钵苗移栽机构移栽臂设计与试验

旋转式水稻钵苗移栽机构移栽臂是移栽作业的执行部件,控制取秧和推秧动作,直接影响移栽机构取秧和推秧的成功率。针对原水稻钵苗移栽机构存在取秧时间长、成功率偏低,无推秧装置、推秧效果差等主要问题,对其移栽臂结构进行改进设计,优化凸轮机构,减小凸轮推程运动角,增加推秧装置。建立机构虚拟样机,研制机构物理样机,开展机构虚拟运动仿真和高速摄像运动试验。比较虚拟仿真和高速摄像试验移栽机构夹取秧苗时间的缩短情况,结果基本一致,表明移栽臂的改进设计是正确和合理的。开展安装不同凸轮机构和有无推秧装置的移栽机构的取秧试验,改进后的机构取秧成功率和推秧成功率分别为94.3%和98.6%,远高于改进前的82.9%和88.6%,表明改进后的机构能够更好地满足水稻钵苗移栽工作要求,且具有很好的工作性能。     

曲柄摇杆式分插机构的动力学分析

曲柄摇杆分插机构具有结构简单、工作可靠和插秧质量好等特点,在水稻分插机中普遍使用.但由于分插机构做反复式运动必然产生惯性力,机构惯性力引起机器振动,限制了水稻插秧机生产率的提高.为此,对水稻插秧机摇杆式分插机构的动力学问题进行了研究,通过对曲柄摇杆分插机构的动力学分析、推秧过程的动力学分析以及碰撞过程的动力学分析,建立了栽植机构的动力学模型.利用上述方法找到了机器振动的原因,采用曲柄附加平衡块和改变缓冲垫刚度的办法,平衡并减少部分惯性力,提高单位时间工作插次,从而提高水稻插秧机的工作效率.     

插秧机推秧装置凸轮和拨叉的理论分析和优化设计

本文对曲柄摇杆式栽植机构推秧装置的凸轮、拨叉的相互位置和各参数进行了分析和研究,建立了数学模型。通过试验验证了模型的可靠性,并编制了优化程序。     

分插机构运动特性分析

分插机构运动特性分析白海英，刘德仁，田临林１引言连杆式机动水稻插秧机分插机构是插秧机主要研究的问题，而推秧凸轮机构的运动直接关系到分插机构的工作性能和质量。在推秧凸轮机构中凸轮廓线设计是否合理将直接影响到构件间的冲击、振动和插秧质量。本文对２ＺＴ－９...     

水稻插秧机现代设计理论与方法

应用现代设计理论与方法对水稻插秧机核心工作部件分插机构进行优化,采用3种方法建立分插机构的理论模型。在建立模型过程中,用电路模拟解决机构冲击载荷引起的弹性动力学问题;对难以用理论演绎建立理论模型的取秧过程,通过试验测定建立数值模型,镶嵌到总的理论模型中;通过台架试验测定分插机构支座力,验证总的理论模型的可靠性;通过高速摄影,测得推秧杆的运动与行星架转角关系,验证推秧装置微分方程。提出了一种解决强耦合性、模糊性、非线性的多目标复杂优化问题的方法——参数导引优化方法,并建立了该方法的理论模型。在VB平台上设计了优化、虚拟制造、虚拟试验和测试软件。该软件在目标函数数值化基础上,增加了优化参数导引功能。     

桑叶采摘机桑枝间歇拨动装置的建模及仿真分析

针对摇杆式桑叶采摘机中桑枝拨动与桑叶采摘之间的时间协调匹配要求,选用圆柱分度凸轮机构作为间歇拨动装置,通过间歇拨动装置和桑叶采摘装置的协调配合,使桑枝能够及时进入圆环刀具口所在位置,保证桑叶的顺利采摘。采用空间包络曲面共轭原理建立了圆柱分度凸轮的数学模型,然后使用Pro/E三维软件的参数化建模功能进行三维设计和建模,结合在摇杆式桑叶采摘机设计中的相关结构参数建立了圆柱分度凸轮机构的虚拟样机模型,通过干涉分析验证了该机构设计的合理性,并将模型转换格式导入ADAMS软件中对其进行动力学仿真。仿真结果表明:该机构模型建立正确,各运动性能较稳定,满足了在桑叶采摘机中的实际应用价值,对该机构的优化设计、加工和安装起到了一定的指导作用。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。