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针对轴承的外径尺寸测量给出了一种基于机器视觉的检测方法。阐述了在Visual C++平台下,采用数字图像处理技术非接触测量轴承外径的方法,包括图像的预处理、图像二值化、圆孔检测技术等。在外圆尺寸获取中,分别采用最小二乘法和霍夫变换技术进行处理,结果表明利用霍夫变换技术获取的外圆尺寸精度更高。并对系统进行标定,得到实际尺寸。分析及试验表明,用该方法对轴承外径进行测量及分析评定在实际应用中是可行的,并具有高效性和实用性。 相似文献
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《拖拉机与农用运输车》2015,(1)
针对轴套零件的几何尺寸测量给出了一种基于机器视觉的检测方法。阐述了在Visual C++平台下,采用数字图像处理技术非接触测量轴套几何参数的方法,包括图像的预处理、改进Canny算子边缘检测、圆孔检测技术等。并对系统进行标定,得到实际尺寸。通过试验得到测量数据,分析了测量误差的原因。分析及试验表明,用该方法对轴套的几何尺寸进行测量及分析评定在实际应用中是可行的,并具有高效性和实用性。 相似文献
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在工业迅猛发展的现代社会,对于测量的要求,尤其是对大尺寸测量要求越来越高,小到微电子,大到航空航天工业产品都需要精密的测量技术。而大尺寸测量对测量技术、测量设备更是提出了新的要求。本文通过参阅国内外的先进经验以及国内外的理论文献,针对应用激光雷达来测试航天航空飞行器这样大尺寸的复杂外形物体的测量技术进行了关键技术的研究,实现了高效率、高质量的三维形貌测量以及在线检测,对工程的实施有很大的帮助。 相似文献
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空气静压轴承是在气体润滑技术基础上发展起来的一种轴承,广泛应用于各种超精密加工或测量设备。本文为了提高空气静压轴承的力学性能、轴承工作参数和设计参数对轴承静、动态性能的影响,参考了轴承的多目标优化设计方法,对轴承的设计参数进行了优化,仅供参考。 相似文献
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针对某核主泵的双向推力轴承在试验过程中出现上部推力瓦温度过高的问题,在不改变油系统、推力轴承结构尺寸及推力瓦数量的条件下,在推力瓦侧面开设不同尺寸的凹槽以控制瓦间流动.经过多方案优选设计出一种改进型推力瓦,以期通过优化推力瓦几何参数解决上部推力瓦温度过高的问题.基于流场数值模拟方法对油系统瓦间流场进行了深入分析,通过对比改进前后2种瓦的瓦间流动分布定性分析推力瓦几何参数对双向推力轴承油系统流动及冷却性能的影响,表明优化后的改进型推力瓦在相同运行条件下大大减轻了油流对冲及阻塞的现象,消除了不合理的回流,增大了进入流道的冷油流量,从而提高了油系统的冷却效果,使得上部推力瓦温度明显降低并达到了设计要求.同时证明了推力瓦几何参数是影响推力轴承油系统特性的重要因素.研究结果能为探究推力瓦几何参数对油系统特性的影响,以及类似轴承系统的推力瓦几何参数优化提供参考. 相似文献
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脱绒棉种的物料学特性研究 总被引：3，自引：0，他引：3
针对棉花种子的物料学特性对棉花精密播种技术的影响,测定了3种脱绒棉种的几何尺寸、形状、千粒质量、摩擦特性、种子载荷与变形的关系等,得出棉种的粒型介于圆锥形和椭圆形之间,棉种的尺寸差异较大,棉种包衣后摩擦性能有所增大,棉种的载荷强度随与种子的饱满度增大而增大。研究结果对棉花精密排种器的研制有指导性意义。 相似文献
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车架是采棉机的重要组件部分,其尺寸大,结构复杂,制造及关键形位公差尺寸测量难度大,采用传统的检测方式效率低、技术要求高、产生成本高,为解决上述问题,提出应用激光跟踪仪对某型号采棉机的车架进行形位公差尺寸检测,介绍激光跟踪仪测量原理及相关参数,阐述激光跟踪仪检测形位公差尺寸的方案及流程,并对检测数据进行分析,验证了图纸的正确性,提高了检测质量和效率。 相似文献
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数控机床测量技术在各种精密工具的加工过程当中具有重要作用,并且直接影响到我国的制造业。分析了数控机床几何误差测量过程当中所出现的主要问题以及未来的发展趋势,并且提供了一定的建议,为有关工作人员提供一定的帮助。 相似文献
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Overland water and salt flows in a set of rice paddies 总被引：1，自引：0，他引：1
E. Playn O. Prez-Coveta A. Martínez-Cob J. Herrero P. García-Navarro B. Latorre P. Brufau J. Garcs 《Agricultural Water Management》2008,95(6):645-658
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. 相似文献
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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。 相似文献
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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。 相似文献
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对《种子法》存在问题的探讨 总被引：1，自引：0，他引：1
李鹏 《农业机械化与电气化》2011,(6):129-130
《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。 相似文献
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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. 相似文献
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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。 相似文献
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Gunter Wriedt Marijn van der Velde Alberto Aloe Fayçal Bouraoui 《Agricultural Water Management》2009,96(5):771-789
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. 相似文献
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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。 相似文献
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车辆ABS控制算法的研究及探讨 总被引：1，自引：0，他引：1
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。 相似文献