Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impac...Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impact,rubbing,combing and grinding.Four types of contact models between grain and threshing components have been constructed correspondently.Grain damage can be regarded as a function of peripheral velocity and contact pattern of impacting.Grain loss can be regarded as a function of contact pattern of rasp bars.Grain loss coming from cleaning and separation in the subsequent process of combing threshing was significantly decreased.Tangential and axial threshing technologies have been applied in grain threshing system widely.It showed that in the combined application,tangential rolls are used to accelerate grain flow,and axial rolls are used to increase threshing quality especially lower loss and damage.Conical concave may take the place of the traditional cylindrical one.With the development of sensor technology and communication technology,intelligent harvesting robot and automatic threshing system will be integrated together to improve grain quality and operation comfort.展开更多
针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator...针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator)进行天线模型的设计以及仿真分析,对NFC天线的3大结构参数(天线边长L_x、线间距S和线径W)进行了仿真分析探究,最后得到以13.56 MHz为中心频率的最优天线结构参数,即L_x=40 mm,S=1 mm和W=0.5 mm。在上述天线结构参数下,优于已有的NFC天线(回波损耗为-22.2 d B),其回波损耗降低至-28.8 d B,-10 d B以下的带宽为0.8 MHz。展开更多
基金This work was supported by the National Natural Science Foundation of China(51705193)National Key Research and Development Project(2017YFD0700302)the Science and Technology Development Project of Jilin Province(20170204016NY).
文摘Threshing is the most important function of grain harvester.Grain loss and damage in harvesting are significantly related to threshing theory and technology.There are four kinds of threshing principles including impact,rubbing,combing and grinding.Four types of contact models between grain and threshing components have been constructed correspondently.Grain damage can be regarded as a function of peripheral velocity and contact pattern of impacting.Grain loss can be regarded as a function of contact pattern of rasp bars.Grain loss coming from cleaning and separation in the subsequent process of combing threshing was significantly decreased.Tangential and axial threshing technologies have been applied in grain threshing system widely.It showed that in the combined application,tangential rolls are used to accelerate grain flow,and axial rolls are used to increase threshing quality especially lower loss and damage.Conical concave may take the place of the traditional cylindrical one.With the development of sensor technology and communication technology,intelligent harvesting robot and automatic threshing system will be integrated together to improve grain quality and operation comfort.
文摘针对现有的13.56 MHz NFC(Near Field Communication)天线因结构而引起回波损耗偏高的问题,设计了一种工作在13.56 MHz的近场通信天线,通过优化天线结构,有效降低了天线的回波损耗。使用Ansoft HFSS(High Frequency Structure Simulator)进行天线模型的设计以及仿真分析,对NFC天线的3大结构参数(天线边长L_x、线间距S和线径W)进行了仿真分析探究,最后得到以13.56 MHz为中心频率的最优天线结构参数,即L_x=40 mm,S=1 mm和W=0.5 mm。在上述天线结构参数下,优于已有的NFC天线(回波损耗为-22.2 d B),其回波损耗降低至-28.8 d B,-10 d B以下的带宽为0.8 MHz。
