数学 外文翻译 外文文献真空压力播种机的数学建模文档格式.docx
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数学 外文翻译 外文文献真空压力播种机的数学建模文档格式.docx
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MathematicalModellingofVacuumPressureonaPrecisionSeeder
D.Karayel1,Z.B.Barut2andA.Ö
zmerzi1
1AkdenizUniversity,FacultyofAgriculture,DepartmentofAgriculturalMachinery,07070,Antalya,Turkey
2Ç
ukurovaUniversity,FacultyofAgriculture,DepartmentofAgriculturalMachinery,Adana,Turkey;
e-mailofcorrespondingauthor:
dkarayel@akdeniz.edu.tr
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
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
1.Introduction
2.Literaturereview
3.Materialsandmethods
4.Resultsanddiscussion
5.Conclusions
Acknowledgements
References
1.Introduction
Precisionsowinghasbeenamajorthrustofagriculturalengineeringresearchformanyyears;
however,mostoftheresearchanddevelopmentworkhasdealtwithseedersforagronomiccrops.
Themainpurposeofsowingistoplacetheseedtoacertainspaceandadepthintheseedbed.Precisionseedersplaceseedsattherequiredspacingandprovideabettergrowingareaperseed.Therearetwocommontypesofprecisionseeders:
beltandvacuum.Precisionvacuumseedershaveameteringplatewithmeteringholesonapredeterminedradius.Avacuumisappliedtothesemeteringholesbymeansofaracemachinedinabackingplate.Astheplaterotates,thevacuumappliedtothemeteringholesenablesthemtopickupseedsfromtheseedhopper.Precisionvacuumseedershavethefollowingadvantagesoverthemechanicalseeders:
betterworkingquality,morepreciseseedrateswithlowerrateofseeddamage,bettercontrolandadjustmentofupkeepanddriftofseeds,andbroaderspectrumofapplicability(Soosetal.,1989).
Aseedershouldplaceaseedinanenvironmentinwhichtheseedwillreliablygerminateandemerge.Anumberoffactorsaffectthespacingofplants.Theseedselectionmechanismmayfailtoselectordropaseedresultinginlargespacingbetweenseeds.Themechanismmayselectanddropmultipleseedsresultinginsmallspacingsbetweenseeds.Seedquality,soilconditions,seederdesignandtheskilloftheoperatorallplayapartindeterminingthefinalplantstand.
Thephysicalpropertiesofseedsareessentialforthedesignofequipmentforhandling,processing,storingandsowingthekernels.Varioustypesofcleaning,grading,separationandsowingequipmentaredesignedonthebasisofthephysicalpropertiesofseeds.However,nomodelhasbeenfoundtodescribeseederparameterssuchasvacuumpressurerelatedwithphysicalpropertiesofseeds.
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.Thisparticularteststandhada150
mmwidebeltwitha7·
5
mlonghorizontalviewingsurface.Aseederrowunitwasmountedonagreasedbeltteststandwhichutilisedanadjustablespeeddrivemechanismtooperatetheseedmeteringdevicesataknownconstantspeed.Sufficientoilwasaddedtothetopsurfaceofbelttocapturetheseedasitwasreleasedfromseederunitwithoutrollingorbouncingofseedonthebeltsurface.Awidevarietyofmeasureswereusedtoqualifyseederperformancewithregardtoplantspacing(Brooks&
Church,1987;
Karayel&
Ö
zmerzi,2001;
Jasa&
Dickey,1982).Sometestsusedperformancemeasuresinvolvingdistancebetweenplantsinthefield.Othertestsusedperformancemeasuresinvolvingdistancebetweenseedsongreasebeltteststandorbyopto-electronicsensorsystem(Bracyetal.,1998;
Smithetal.,1991;
Lanetal.,1999).Afewtestsusedperformancemeasuresinvolvingdistancebetweenseedssownintosoil(Panning,1997).
Aprecisionvacuumseederunitwasoperatedinalltreatments(Fig.1).Theseederunitwasageneralpurposeseederdesignedforrowcropssuchasmaizeandsoyabeans.Threedifferentvacuumplateswithdifferentholediameterswereusedinthemeteringmechanism.Thediameterofvacuumplateswere230
mm.Theholesweredrilledalonga200
mmdiameterpitchcircle.Theholesofthevacuumplatewere3·
mmindiameterformaizeI,II,soyabeanandcotton;
2·
mmindiameterforwatermelonI,II,melon,andcucumberand1·
mmindiameterforsugarbeetandonion.Theseedplateoperatedinaverticalplane.Airsuctionfromtheholesoftheseedplatecausedtheseedtosticktotheholes.Thestuckseedwasreleasedfromtherotatingplatebytemporarilypreventingairflow.Theabsenceofsuctionallowedtheseedtobedroppedintosoil.Ithadnoseedtubeandtheseedfallheight(12
mm)oftheseederwaskeptlowinordertoreducethechanceofnon-uniformspacingwhichcanoccurduetothebouncingofseed,ifdroppedfromhighplane.Thevacuumlevelwasregulatedbyadjustingthesizeofanopeninginthevacuumlineofseederandmeasuredwithamanometer.
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).Themultipleindexisthepercentageofspacingsthatarelessthanorequaltohalfofthetheoreticalspacingandindicatesthepercentageofmultipleseeddrops.Themissindexisthepercentageofspacingsgreaterthan1.5timesthetheoreticalspacingandindicatesthepercentageofmissedseedlocationsor‘skips’.Qualityoffeedindexisthepercentageofspacingsthataremorethanhalfbutnomorethan1.5timesthetheoreticalspacing.Qualityoffeedindexis100%minusmissandmultipleindexandindicatesthepercentagesofsingleseeddrops.Precisenessisthecoefficientofvariationofthespacingsthatareclassifiedassinglesafteromittingtheoutliersconsistingofmissesandmultiples.
KachmanandSmith(1995)recommendedusingmissindex,multipleindex,qualityoffeedindexandprecisenessforsummarisingtheuniformityofseedermeteringratherthanmeanorsamplecoefficientof
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