共查询到20条相似文献，搜索用时 812 毫秒
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深松铲在作业过程中存在工作阻力大、磨损严重的问题,因此良好的耐磨减阻性能和冲击韧性对改善深松铲的作业效果、延长深松铲的使用寿命具有极其重要的意义。仿生是深松铲优化设计的一种有效方法,本文归纳了仿生深松铲研究的生物仿生原型以及采用的仿生方法,从动物爪趾形态仿生、生物表面特殊几何结构仿生和复合仿生的角度,对仿生深松铲的耐磨减阻性能研究现状进行分析和总结。并基于已有研究提出仿生深松铲在未来的研究中向生物的力学特性仿生、功能特征仿生方面拓展,可以将鸟类、植物等的耐磨减阻特征作为新的仿生探索领域,也可以尝试将仿生设计与表面改性技术等其他技术方法相结合进行研究,以期为仿生深松铲的耐磨减阻性能研究提供参考,促进深松铲的耐磨减阻性能优化设计研究。 相似文献
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针对当前铧式犁在棉田土壤犁耕作业过程中易黏附、阻力大、能耗高等问题,立足两种典型棉田土壤,以犁体、棉田土壤和两者之间的相互作用为研究对象,提出犁体曲面模型优化和表面结构仿生相结合的方法。以穿山甲体表的鳞片三角圆弧状结构和蜣螂体表的凸包结构相结合作为仿生原型,研制一种棉田仿生脱附减阻犁体,分别对两种棉田土壤的物理和化学特性进行试验测定并建立离散元模型。进行传统犁体与仿生犁体的耕作过程仿真与试验,在1号土样中仿生犁体相对传统犁体减阻5.4%,土壤减粘性能提升44.15%;在2号土样中仿生犁体相对传统犁体减阻7.8%,土壤减粘性能提升45.49%,研究结果表明仿生犁体对棉田土壤减粘降阻效果明显。 相似文献
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荆巧锋 《拖拉机与农用运输车》2007,34(3):58-59
从解活塞裙润滑的雷诺方程出发,以解析曲面模拟热态时活塞裙部型面的形状,进而求出几个重要的活塞裙部参数。通过实验证明,这种计算方法是可行的,有利于在开发阶段设计出较好的活塞裙,减少试验次数。 相似文献
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陈嘉康 《拖拉机与农用运输车》1983,(3)
本文描述了活塞裙热变形的特性,对热态下裙部应有的型面进行了探索。以活塞裙温度场为根据,热变形为基础,机械力引起的变形作为参考,对裙部型面进行造型,通过实践进行修正,从而达到设计目的. 相似文献
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SL105系列柴油机活塞裙部外型面设计 总被引：1，自引：1，他引：0
曹志芬 《拖拉机与农用运输车》2000,(2):26-29
介绍了 SL 10 5系列柴油机活塞中凸变椭圆裙部外型面设计的理论依据和具体计算方法。该型活塞裙部与气缸套贴合良好 ,无拉缸擦伤现象。经试验实测 ,柴油机性能改善 ,燃油消耗率、机油消耗率有明显降低 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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车用发动机润滑油失效规律与更换周期研究 总被引：7，自引：0，他引：7
研究在正常使用条件下１０Ｗ／３０－ＱＣ级润滑油用于某型车用发动机时所表现的失效规律,确认期服从两参数Ｗｅｉｂｕｌｌ分布,并给出分布的尺度参数η和形状参数ｍ之最佳线性无偏估计（ＢＬＵＥ）同时,还为定量分析,计算车用发动机润滑油的使用可靠性和合理确定其更换周期提供了一套可供借鉴的方法,并给出了具体的计算实例。 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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赵国杰 《农业机械化与电气化》2011,(4):106-107
乡（镇）农技推广体系是农业发展的关键。介绍朝阳市农业技术推广体系的现状,针对目前体制及运行机制、服务手段等方面存在的问题,提出适合朝阳市乡（镇）农技推广体系改革与发展的对策,以期对全省农技推广体系改革和发展起到一些借鉴作用。 相似文献
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苑庆刚 《农业机械化与电气化》2010,(3):52-54
草莓果味酸甜爽口,营养价值高,为人们所喜爱的应市鲜果之一。由于草莓易受损伤和微生物侵染,因此其采收、贮藏过程极为重要。介绍草莓采收过程中的注意事项以及11种贮藏保鲜技术的实施步骤和操作方法,推介9种加工方式,为草莓产业化提供技术支持。 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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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