1、毕业设计(论文)外文资料翻译院 系专业学生姓名班级学号外文出处附件：1.外文资料翻译译文（约3000汉字）； 2.外文资料原文(与课题相关的1万印刷符号左右)。指导教师评语：指导教师签名：年月日外文资料原文J.agric. Engng Res. ,(2001) 78(1),43-60doi:10.1006/jaer.2000.0632,available online oatPM-Power and MachinaryStripping of Leaves and Flower Heads to improve the Harvestingof Fibre Hemp （Received 11
2、february 2000;accepted in revised from 11 August 2000；published online 25 October 2000）Hemp(Cannabis sativa) grown for fibre needs to be retted after cutting to allow the separation of fibre from the stem core.Drying of the mown stems in necessary both before and after retting but drying is likely t
3、o be hindered by the presence of leaves and flower heads on the stems.Delays in drying after retting have serious implications for fibre quality and core spoilage when baled.The aim of this work was to determine if leaves and flower heads could be removed from standing stams by powered rotor just pr
4、ior to mowing.In a laboratory apparatus that propelled 40 stems past a rotor,the effectiveness of the method was established and the influence of rotor speed,forward speed and tooth design were examined.At every one of a range of setting ,more than 92% of the contacted leaf and flower head was remov
5、ed form the top 900mm of the tested stems.A device constructed for field trials comprised a 1.2m wide rotor on a tractor-mounted arm.Trials showed it to be effective over a range of forward speed,rotor speed and contact height.At its optimum setting of these three variables,5.8km h-1,645min-1 and 1.
6、6m,it removed 95% of the contacted leaf and flower head material.A practical implementation would probably comprise a single machine with stripping rotor mounted aheda of the stem-cutting elements.2001 Silsoe Research InstituteNotationMa mass of leaf material leaf unstripped above h height,m the nom
7、inal stripping height,kg m stem mass ,gMb mass of leaf material leaf unstripped below r rotor speed,min-110-3 the nominal stripping height,kg s overall stripping efficiencyMs mass of material removed by the stripping s stripping efficiency of Rotor,kg material above the f forward speed,km h-1 nomina
8、l stripping height1.IntroductionHemp(Cannabis sativa)is grown in northern Europe for production of fibres from the sten,which have a high tensile strength and can be used in pup products, composites and industrial textiles.Particles of stem core are absorbent and are used as animal bedding.In curren
9、t practice, the stems are cut when still grenn and before full seed set when leaves,flower heads and seed heads are present.Once cut,the stems are retted,i.e. exposed in a swath to dry and rewet so that they undergo micro-biological digestion of the chemical bonds between the fibre bundles in the ba
10、st or outer layer and the surrounding cells.This makes possible the extraction of the fibre from the dried stems with minimal fibre damage. When the stems have retted to the optimum degree,the fibres are still of high strength but are readily separated from the remainder of the stem material. If ret
11、ting is allowed to continue, the fibres are weakened and lose value.There fore,it is important to collect the stems at the optimum stage of retting for storage and later processing .Unless the stems are collected dry enough to prevent microbial action,further are generally not good for drying after
12、retting,which takes some 3-6 weeks after harvest in early September in the UK, so it is important that swaths of retted stems dry quickly when conditions are favourable so as to avoid over-retting.Removal of the leaves and flower heads before the stems are swathed is also likely to promote more even
13、 retting by better exposing the whole length of the stems to drying.Leaf and flower head removal is also likely to increase the in-swath drying rate of the stems from harvested moisture to the moisture at which retting will start,thus minimizing the time for which the hemp crop occupies the field.Ai
14、r can more easily penetrate the swath,and the leaves and flower heads contain additional moisture that must be evaporated.This is of particular importance when baling the retted crop because the seed heads tend to remain damp and later cause partial spoilage of the baled crop.In addition,the removal
15、 of the leaf and seed head also reduces the amount of material to be baled,stored,transported and processed,resulting in lower costs.It returns some plant material to the soil to improve soil fertility and structure and reduces waste at the processing plant, waste that may be classified as industrial waste and hence attract higher disposal charges.Several studies
