完整版毕业设计外文翻译371.docx

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