完整版毕业设计外文翻译371.docx
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完整版毕业设计外文翻译371.docx
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完整版毕业设计外文翻译371
1.Introduction……………………………………………………3
引言……………………………………………………………17
2.Materialsandmethods…………………………………………4
材料和方法……………………………………………………18
3.Resultsanddiscussion…………………………………………7
结果与讨论……………………………………………………21
4.Conclusions……………………………………………………13
结论…………………………………………………………26
5.Acknowledgements…………………………………………13
鸣谢………………………………………………………26
MathematicalModellingofVacuumPressureonaPrecisionSeeder
D.Karayel1,Z.B.Barut2andA.Özmerzi1
1AkdenizUniversity,FacultyofAgriculture,DepartmentofAgriculturalMachinery,07070,Antalya,Turkey
2ÇukurovaUniversity,FacultyofAgriculture,DepartmentofAgriculturalMachinery,Adana,Turkey;e-mailofcorrespondingauthor:
Received9July2003; accepted19January2004. Availableonline13April2004.
Abstract
Thepurposeofthisresearchwastodeterminetheoptimumvacuumpressureofaprecisionvacuumseederandtodevelopmathematicalmodelsbyusingsomephysicalpropertiesofseedssuchasonethousandkernelmass,projectedarea,sphericityandkerneldensity.Maize,cotton,soyabean,watermelon,melon,cucumber,sugarbeetandonionseedswereusedinlaboratorytests.Onethousandkernelmass,projectedarea,sphericityandkerneldensityofseedsvariedfrom4.3to372.5 g,5–77 mm2,38.4–85.8%and440–1310 kg m−3,respectively.Theoptimumvacuumpressurewasdeterminedas4.0 kPaformaizeIandII;3.0 kPaforcotton,soyabeanandwatermelonI;2.5 kPaforwatermelonII,melonandcucumber;2.0 kPaforsugarbeet;and1.5 kPaforonionseeds.
Thevacuumpressurewaspredictedbymathematicalmodels.Accordingtotheresults,thefinalmodelcouldsatisfactorilydescribethevacuumpressureoftheprecisionvacuumseederwithachi-squareof2.51×10−3,rootmeansquareerrorof2.74×10−2andmodellingefficiencyof0.99.
Nomenclature
Nomenclature
a,b,c,d,eregressioncoefficients
Emmodellingefficiency
Ermsrootmeansquareerror
kexpexperimentalvacuumpressure,kPa
kexp,meanmeanvalueofexperimentalvacuumpressure,kPa
kprepredictedvacuumpressure,kPa
Llength,mm
m1000onethousandkernelmass,g
Nnumberofobservation
nnumberofconstantsinthemodel
Pprojectedarea,mm2
Pvvacuumpressure,kPa
pprobability
R2coefficientofdetermination
Tthickness,mm
Wwidth,mm
φsphericity,%
χ2chi-square
ρkkerneldensity,kg m−3
ArticleOutline
Nomenclature
1.Introduction
2.Literaturereview
3.Materialsandmethods
4.Resultsanddiscussion
5.Conclusions
Acknowledgements
References
1.Introduction
Precisionsowingamajorthrustofagriculturalengineeringresearchformanyyears;purposeofsowingistoplacetheseedtoacertainspaceandadepthintheseedbed.Precisionseedersplaceseedsattherequiredspacingandprovideabettergrowingareaperseed.Therearetwocommontypesofprecisionseeders:
beltandvacuum.Precisionvacuumseedersapredeterminedradius.Avacuumisappliedtothesemeteringabackingplate.Astheplaterotates,thevacuumappliedtothemeteringvacuumseedersanenvironmentinwhichtheseedwillreliablygerminateandemerge.Anumberoffactorsaffectthespacingofplants.Theseedselectionmechanismmayfailtoselectordropaseedresultinginlargespacingbetweenseeds.Themechanismmayselectanddropmultipleseedsresultinginsmallspacingsbetweenseeds.Seedquality,soilconditions,seederdesignandtheskilloftheoperatorallplayapartindeterminingthefinalplantstand.
Thephysicalpropertiesofseedsareessentialforthedesignofequipmentforandsowingequipmentaredesignedonthebasisofthephysicalpropertiesofseeds.However,nomodelfoundtodescribeseederparameterssuchasvacuumpressurerelatedwithphysicalpropertiesofseeds.
Thephysicalpropertiesoftheseedsarethemostimportantfactorsindeterminingtheoptimumvacuumpressureoftheprecisionvacuumseeder.Inthisstudy,usingsomeofthese,e.g.onethousandkernelmass,projectedarea,sphericityandkerneldensity,mathematicalmodelsweredevelopedtopredictoptimumvacuumpressure.Theexperimentalvaluesofvacuumpressureweredeterminedfromlaboratorytestprocedure.
2.Materialsandmethods
Thelaboratorytestprocedureinvolvedtestingthemeteringuniformityoftheseederatthedifferentvacuumpressurewiththedifferentseeds:
twodifferentmaizevarieties(maizeIandmaizeII),cotton,soyabean,twodifferentwatermelonvarieties(watermelonIandwatermelonII),melon,cucumber,sugarbeetandonion.Theseseedsrepresentseveralseedshapesvaryingfromspherical(soyabean,maizeII)toflatandelongated(maizeI,melon,watermelon,cucumber).Twodifferentvarietiesofmaizeandwatermelonseedswereselected,becauseofthemorediverserangeofonethousandkernelmass,projectedarea,sphericityorkerneldensitythanotherseeds.Allseedsusedinthisresearchwereuncoatedseed.ThemaindimensionsoftheseedsaregiveninTable1.Theseederwassettospacetheseedsascloselytotherecommendedspacingaspossible.
Table1.Meansandstandarderrorsoftheseeddimensions
Agreasebeltteststandwasusedtodeterminesowinguniformityofeachseedatthedifferentvacuumpressures.Thisparticularteststandagreasedbeltteststandwhichutilisedanadjustablespeeddrivemechanismtooperatetheseedmeteringdevicesataknownconstantspeed.Sufficientoilwasaddedtothetopsurfaceofbelttocapturetheseedasitwasreleasedfromseederunitwithoutrollingorbouncingofseedonthebeltsurface.Awidevarietyofmeasureswereusedtoqualifyseederperformancewithregardtoplantspacing(Brooks&Church,1987;Karayel&Özmerzi,2001;Jasa&Dickey,1982).Sometestsusedperformancemeasuresinvolvingdistancebetweenplantsinthefield.Othertestsusedperformancemeasuresinvolvingdistancebetweenseedsongreasebeltteststandorbyopto-electronicsensorsystem(Bracyetal.,1998;Smithetal.,1991;Lanetal.,1999).Afewtestsusedperformancemeasuresinvolvingdistancebetweenseedssownintosoil(Panning,1997).
Aprecisionvacuumseederunitwasoperatedinalltreatments(Fig.1).Theseederunitwasageneralpurposeseederdesignedforrowcropssuchasmaizeandsoyabeans.Threedifferentvacuumplateswithdifferentthemeteringmechanism.Thediameterofvacuumplateswere230 mm.ThediameterformaizeI,II,soyabeanandcotton;2·5 mmindiameterforwatermelonI,II,melon,andcucumberand1·5 mmindiameterforsugarbeetandonion.Theseedplateoperatedinaverticalplane.Airsuctionfromtheallowedtheseedtobedroppedintosoil.Itordertoreducethechanceofnon-uniformspacingwhichcanoccurduetothebouncingofseed,ifdroppedfromopeninginthevacuumlineofseederandmeasuredwithamanometer.
Fig.1.Themeteringmechanismoftheprecisionvacuumseeder:
1,vacuumplate;2,seed;3,seedbox;4,airsuctioncanal;5,aircut;6,furrowopener
Theseederwasoperatedoverthegreasedbeltatagroundspeedof1 m s−1andadjustedtofourvacuumpressures2.0,3.0,4.0and5.0 kPaformaizeI,II,soyabeanandcotton;2.0,2.5,3.0and3.5 kPaformelon,watermelonI,IIandcucumber;1.0,1.5,2.0and2.5 kPaforsugarbeetandonionseeds.Seedspacingsweremeasuredoveradistanceof7 m.Theseederwasadjustedtodeliveranominalseedspacingof230 mmformaizeIandII,170 mmforcotton,105 mmforsoyabean,550 mmforwatermelonI,II,melonandcucumber,150 mmforsugarbeetand85 mmforonion.
ThesowinguniformitywasanalysedusingthemethodsasdescribedbyKachmanandSmith(1995).Themultipleindexisthepercentageofspacingsthatarelessthanorequalto1.5timesthetheoreticalspacingandindicatesthepercentageofmissedseedlocationsor‘skips’.Qualityoffeedindexisthepercentageofspacingsthataremorethan1.5timesthetheoreticalspacing.Qualityoffeedindexis100%minusmissandmultipleindexandindicatesthepercentagesofsingleseeddrops.Precisenessisthecoefficientofvariationofthespacingsthatareclassifiedassinglesafteromittingtheoutliersconsistingofmissesandmultiples.
KachmanandSmith(1995)recommendedusingmissindex,multipleindex,qualityoffeedindexandprecisenessforsummarisingtheuniformityofseedermeteringratherthanmeanorsamplecoefficientofvariation.Theyconcludedthatseveralmeasureswereneededtogiveatruepictureofseederuniformity.Forthisstudy,missindex,multipleindex,qualityoffeedindexandprecisenessarereported.
Variousphysicalpropertiesofseedsincludingkerneldensity,projectedarea,sphericityandonethousandkernelmassarethemostimportantfactorsindeterminingtheoptimumvacuumpressureoftheprecisionvacuumseeder(Barut,1996).Thephysicalpropertiesoftheseedsweredeterminedbythefollowingmethods:
Lineardimensions,i.e.length,thicknessandwidthweremeasuredbyusingaverniercaliperwithasensitivityof0.01 mm.Sphericityφwerecalculatedbyusingthefollowingequation(Mohsenin,1970):
(1)
where:
Listhelength;Wisthewidth;andTisthethicknessinmm.
Onethousandkernelmasswasmeasuredbyanelectronicbalancewithasensitivityof0.001 g.
Kerneldensitywasmeasuredbytheliquiddisplacementmethod.Toluene(C7H8)wasusedratherthanwaterbecauseitwasnotabsorbedbyfruits(Mohsenin,1970;Ögöt,1998).
Projectedareawasdeterminedbyusingadigitalcamera(KodakDC5000)andSigmaScanPro5program.
Fortheestimationofthevacuumpressure,inrelationtokerneldensity,projectedarea,sphericityandonethousandkernelmass,mathematicalmodelsweredeveloped.Thesuitabilityofthefinalmodelwascomparedandevaluatedusingchi-square,rootme
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