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《中国农机化学报》2018,(11)
利用改装隔振杠杆压坨式张紧系统后的MJ3310A跑车带锯机试验,以锯轮转速、压坨重量、上下锯卡距离、树种、进料速度为因素,以带锯条横向振动位移为检验目标,根据L25(56)正交试验法设计试验,采用652U型振动信号采集和分析仪,对负载下完好带锯条在不同锯切参数水平下的横向振动位移进行采集和数据分析。根据数据分析,对安装隔振杠杆压坨式张紧系统跑车带锯机的完好带锯条横向振动位移影响的主次因素顺序是锯卡距离、压坨重量、锯轮转速、进料速度、树种。选取合理的锯切参数,以桦木为例,改装隔振杠杆压坨式张紧系统后的跑车带锯机锯切桦木时优化的锯切参数选择方案为A4B4C5E4,即锯轮转速860rpm,压坨重量95N,锯卡距离650mm,进料速度27m/min,隔振器效应明显,此时带锯条横向振动位移小,为0.483mm。 相似文献
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《农业装备与车辆工程》2015,(10)
以发动机正时链传动系统的布局设计为研究目的 ,通过对正时链条自由长度、紧边长度、正时链传动系统的摩擦、张紧器及链板的结构和工艺等进行优化设计来降低系统的摩擦损失及保证系统运行的稳定性。同时通过计算和实验研究表明增加链条的节数可以增加θ动值以稳定T/F值,但同时也会增大摩擦损失,因此在设计时需要选择合适的链条节数。 相似文献
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建立了摸拟汽车发动机驱动二次元件的转速控制系统和车桥轮边加载二次元件的转矩控制系统的数学模型.在此基础上,对校正前后的转速和转矩控制系统进行了开环频域特性分析.并利用MATLAB软件,对该系统进行了输出响应特性仿真,依此对系统的控制精度和响应特性进行了较为详细的分析.所得有关结论,为汽车车桥二次调节模拟加载系统的设计提供了依据. 相似文献
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为提高发动机的工作效率、降低耗油率,使发动机的散热量能够按实时工况来调节,发动机工作温度维持在燃油效率高的温度,设计了汽车发动机电控冷却系统。采取英飞凌芯片作为控制器对冷却系统中的冷却风扇和水泵进行了联合控制,根据发动机实时所需的工作温度调节冷却风扇和水泵的转速。本系统设计简单、结构简单,解决了传统发动机不能按需调节发动机工作温度、噪声大等问题。 相似文献
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5SZ系列自走式液压调整双折叠输送机主要由行走系统、调节系统、传送带、发动机、底盘、液压系统等零部件组成。在选择这些零部件时要根据运距、输送物料的性质及运输机所在场合等来确定。带式输送机速度要依据带宽及运送物料的性质、运距等进行确定。根据所选资料,确定驱动形式和计算各张紧力,根据计算结果进行功率计算来选择液压马达的型号;然后根据以上数据进行标准件的选择和验算,并进行总体布置设计和画出相关零部件图。 相似文献
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用ADAMS的履带车辆工具箱(ATV),建立东方红C1002拖拉机的行走系统的多体系统动力学模型。应用所建立的模型,对张紧缓冲装置的主要参数、静态运动学与力学特性进行研究,还对车辆直线行驶遭遇障碍物、原地转向以及倒车行驶工况进行动态仿真。研究发现张紧缓冲装置中主要参数对张紧力的平均值和极值差都有比较大的影响。履带拖拉机越障时,行走机构将承受很大的冲击载荷,在模拟工况中,冲击载荷峰值达到静态设计载荷1.5~2倍。因此,在履带车辆行走机构强度设计时必须高度重视越障引起的冲击载荷。 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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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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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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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