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Dynamic characteristics of dwarf Chinese hickory trees under impact excitations for mechanical fruit harvesting

International Journal of Agricultural and Biological Engineering 2015年第1期8卷 17-25页

作者： Du Xiaoqiang Wu Chuanyu He Leiying Tong Junhua School of mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Zhejiang Province Key Laboratory of Transplanting Equipment and Technology Hangzhou 310018China

mechanical vibration is an effective fruit harvesting *** evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact *** primary resonance frequencies of the tree can be determined based on the acceleration admittance *** effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was *** responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree *** results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree *** attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter *** the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain *** branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration *** those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance *** impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.

关键词： Chinese hickory mechanical harvest fruit acceleration admittance vibration transmission impact test

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In-field harvest loss of mechanically-harvested maize grain and affecting factors in China

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International Journal of Agricultural and Biological Engineering 2021年第1期14卷 29-37页

作者： Liangyu Hou Keru Wang Yizhou Wang Lulu Li Bo Ming Ruizhi Xie Shaokun Li The Key Laboratory of Oasis Eco-Agriculture Xinjiang Production and Construction Corps/Agricultural CollegeShihezi UniversityShihezi 832000XinjiangChina Institute of Crop Sciences Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and EcologyMinistry of Agriculture and Rural AffairsBeijing 100081China

Field harvest loss is a common problem of maize grain mechanical harvesting in China and *** 2012 to 2019,2987 groups of samples for the quality of mechanical grain harvesting in field were obtained in 21 major maize-producing provinces,cities,and regions of *** analysis performed in this study showed that the average harvest loss of fallen ears was equivalent to 76.5%of the total harvest loss,indicating that the harvest loss in the mechanical harvesting of maize grain mainly came from the loss of fallen ***,statistical analysis of the harvest loss in different ranges of grain moisture contents showed that,when the grain moisture content fell below 20%,the harvest loss rate of fallen ears and the total harvest loss rate both increased sharply,and the harvest loss of fallen ears increased faster than the harvest loss of fallen grain with a decreasing grain moisture ***,the results of multi-point experiments and harvest experiments in different periods showed that,during harvesting time,the harvest loss of fallen ears caused by lodging was the main reason for in-field harvest losses in the mechanical harvesting of maize *** from the above mentioned,the test results of 35 groups of harvesters for the in-field mechanical harvesting of maize grain showed that the harvester types and their operating parameters were important factors affecting the harvest loss in the mechanical harvesting of maize ***,the principal paths to reduce harvest loss in the mechanical harvesting of maize grain are to breed lodging-resistant maize varieties,adopt reasonable planting densities,cultivate healthy plants,develop harvesters with low harvesting loss,intensify the training of operators,and harvest at an appropriate time.

关键词： maize grain mechanical harvest harvest losses affecting factors fallen ears fallen grain

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