外文翻译英文.docx
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外文翻译英文.docx
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外文翻译英文
Title:
Modellingoftransportcostsandlogisticsforon-farmmilksegregationinNewZealanddairying
MaterialSource:
ComputersandElectronicsinAgriculture
Author:
A.E.Dooley,Parker,H.T.Blair
Abstract
On-farmmilksegregationtokeepmilkwithhighvaluepropertiesseparatefrombulkmilkwillaffecttransportlogistics.Separatemilkcollection,eitherasindependentrunsfordifferentmilktypes,orstorageofdistinctmilktypesinthetruckandtrailerunits,mayincreasethelengthandnumberofrunsrequired.Twocontrastingregions,withdifferentfarmsizesandroadingnetworksweremodelled,attwostagesoflactationover20years.Thirtyfarmsineachregionweremodelledwith0,25,50and100%offarmsperregionchangingmilktypesoveratransitionperiodofupto18years.Geneticalgorithmsoftwarewasusedtosearchfortheorderofthefarmmilkcollectionpick-upswhichgaveanoptimal,leastcostsolutionformilkcollectionforeachprescribedsetofinputs.Milkcollectioncostswithinscenariowerevariableovertimedependingontheamountsofthedifferentmilktypes,increasingwheneveranotherrunwasrequired,thendecreasingovertimeasthemilkloadincreased.Milkcollectioncostissmallrelativetomilkincome,withthestatusquo(SQ)costformilkcollectionbeinglessthanNZ$9.61/klfortheNorthIslandandNZ$13.53/klfortheSouthIslandfarmsets.Theincreasedtransportcostsassociatedwithcollectingtwomilktypesrangedfrom4.5to22.0%moreforthedifferentscenarios.TheextracosttoanaveragesizeNorthIslandfarmchangingsystems(25%farmschanging),comparedtoanequivalentstatusquofarm,wouldbebetweenNZ$307andNZ$1244peryear.Fewerfarmschangingtodifferentiatedmilkproductionincreasedthecostsperkilolitreofdifferentiatedmilk.
Keywords:
Milktransport;Scheduling;Milksegregation;Collectioncosts
1.Introduction
Milkwithhighvaluepropertiescanbesegregatedfrombulkmilk,bothon-farmand
betweenfarms,allowingittobeprocessedintonicheproducts,e.g.,milkwithparticularproteinssuchasA2β-caseinorBβ-lactoglobulinmilk,lightcolouredmilk,organicmilkormilkwithantibioticproperties.On-farmsegregationofhighvaluemilkhasassociatedeffectsonthelogisticsofmilkcollection.Currently,NewZealanddairycompaniesdeductabout$0.04/lfromfarmers’payoutstocovercostsassociatedwiththetransportationandstorageofbulkmilk,andtheremovalofwateratthefactory.Milksegregatedatthefarmislikelytoincreasethiscostbecauseofhighertransportandmilkstoragecosts.Separatemilkcollection,eitherasindependentrunsfordifferentmilktypes,orstorageofdistinctmilktypesinthetruckandtrailerunits,mayincreasethelengthandnumberoftripsrequired.Extravatsandmilksilosmaybealsorequiredtosegregatemilk.Itfollowsthatproductsfromsegregatedmilkmustcommandeitherahighermarketvalueorareducedprocessingcost,tooffsettheseadditionalcosts.
Thesoftwareusedbydairyandothertransportcompaniestooptimisescheduling
decisionsiscommerciallysensitiveandspecifictoacompany’sparticularoperation.Furthermore,thissoftwaretypicallyrelatestothecollectionofonlyonemilktype.Asimulationmodelforstudyingtransportlogisticswas,therefore,constructedtoquantifythesecostsandthepracticalitiesofcollectingdifferentmilks.Increasedtransportcostsassociatedwithmilkchangingfromonetypetoanotherweredeterminedbymodellingsituationswherenone,25,50%andallfarmsinacollectionareachangedtoanothermilktypeovera20-yearperiod.Implicationsforfarmersandtheirmilkprocessorinadoptingon-farmmilksegregationarediscussed.
2.Method
2.1.Problemdescription
Twocontrastinggeographicconfigurationsofdairyfarmsweremodelled,attwostagesoflactation(peakandlate).Thesmaller,moreconcentrateddairyfarmswererepresentedbyaNorthIslanddairyingareaandthelarger,moredispersedfarmswererepresentedbyaSouthIslanddairyingarea.ThemodelwasdevelopedusingMicrosoftExcelspreadsheets,andtheEvolvergeneticalgorithmsoftwaretosearchfortheorderofthefarmmilkcollectionpick-upswhichgaveanoptimal,leastcostsolutionformilkcollectionforeachprescribedsetofinputs.
Ahypotheticalsetof30farmswasdefinedforeachregion,basedonactualfarmmilk
productiondatasuppliedbyaNewZealanddairycompany.TheNorthIslandsetoffarmsrepresentedanareawithsmallherds(average=177cowsperfarm)nearthefactory,whereastheSouthIslandfarmshadlargeherds(averagegreaterthan500cows,LivestockImprovementCorporation(LIC),1999)onfarmsphysicallyfurtherapart.Eachfarmproducedoneortwotypesofmilk,henceforthlabelled“milkA”and“milkB”.Thecollectionofeachmilktype,oneachfarm,wasdefinedasaseparatestop,giving60possiblemilkcollectionstops.Thenumberofstopsandthemilkvolumescollectedvariedoverthe20yearsaccordingtothenumberoffarmschangingfrommilkAtomilkBmilkandtherateofchangebetweenmilktypeswithinfarms.Allherdswereseasonallycalvedinthespring.
2.2.Scenariosexamined
Themodelsimulatedtheeffectofsomefarmswithinacatchmentchangingfromthe
production,andsegregation,ofmilkAtomilkBmilkovertimeonchangingmilkvolumesofthetwomilktypes,milkcollectionrequirementsandcollectioncosts.Fourscenariosofchangeinamilkcollectionareawereexplored:
nofarms(statusquo(SQ)),25%(8farms),50%(15farms)andallfarmschangingtomilkBmilk(Table1).Foreachscenario,farmswererandomlyallocatedtothetwogroups(changingornot).NorthandSouthIslandherds(smallandlargevolumesperstop)andeitherdailyoreveryotherdaycollectionsweresimulated.
TheinitialpercentageofmilkBmilkonfarmsinvolvedinachangeinmilktyperangedfrom26to47%,withherdsrandomlyallocatedtofivedifferentgenefrequenciesassociatedwiththedifferentamountsofmilkB.Once95%ormoreofthemilkfromaherdwasmilkB;itwasassumedallmilkwasmilkB,sinceforpracticalpurposes,itisunlikelyaseparatestopwouldbemadefor5%oftheherd’sproduction.Thetimetakenforaherdtochangefromoneparticulartypeofmilktoanotherusinggeneticselectiontookabout14years,butthiswasinfluencedbytheinitialnumberofmilkBcowsintheherdandassociatedgenefrequency.
Table1Transportmodelscenariosrun
Island
Stageoflactation
Collection(milktypesperrun)
%Farmschanging
North
Peak
Daily
(2)
None,25,50,all
North
Late
Everysecondday
(2)
None,25,50
North
Peak
Everysecondday
(2)
25,50
South
Peak
Daily
(2)
None,25,50
South
Peak
Daily
(1)
None,25,50
Tosimplifytheanalyses,itwasassumedthatallfarmerswouldcommittosupplying
MilkBmilkornot,withinthefirst3years.FarmschangingtomilkBsupplywererandomlyallocatedtoaninitialyearofchangeataratioof3:
4:
1foryears1–3forthe25and50%scenarios.Whereallherdsinacollectionareachanged,itwasassumedthatthiswasapolicydecisionandthatallfarmschangedinthefirstyear.
Abridgingpointenroute,attheedgeofthecollectionareaclosesttothedairyfactory
wasselected.Consequently,onlythedistancesbetweenfarms,farmsandthebridgingpoint,andthebridgingpointandthefactory,neededtoberecorded.MellalieuandHall(1981)adoptedasimilarapproachinmodellingamilktransportplanningmodel.Thedistancebetweenthedairyfactoryandthebridgingpointwasassumedtobe25and85kmfortheNorthandSouthIslands,respectively.
2.3.Milkproductionvolumes
Productionforeachfarminyear1wasbasedonactualproductiondataforthefarms
inthe1997/98(NorthIsland)and1998/99(SouthIsland)lactations.Milkcollectionwas
simulatedforthepeaksupplydayforboththeNorthandSouthIslands,andthefirstday
whenallfarmswereoneveryseconddaypick-upduringlatelactationfortheNorthIsland.
TheflatterlactationcurveintheSouthIslandcomparedtotheNorthIsland(LIC,1999)
meanttheamountcollectedonthefirstdayofeveryseconddaycollectioninlatelactation
wassimilartothedailypick-upduringpeaklactation,therefore,thisscenariowasnot
modelled.These2lactationdayssimulatedtwopointsontheseasonalsupplymilkvolumecurvefromwhichothertransporteffectscouldbeinterpolated.
Theaverageamountofmilkfortheherdsinyear1atpeaklactationwas3094l(σ=1544)
perdayfortheNorthIslandand11577(σ=3629)fortheSouthIsland.Inlatelacta-
tion,thisvaluewas1920l(σ=1036)everyseconddayfortheNorthIsland.Milkyield
perfarmwasassumedtoincrease,basedonthehistoricaverage,by1.5%perhectare
peryear(LIC,1999).ThepercentageofmilkBproducedoverthe20yearsisshowninTable2.
2.4.Tankerparameters
Tankercapacitywas11,300lforthetruckunitand17,500lforthetrailerunitbased
onapproximately95%loadingforactualmilkvolumes(Spooner,GeneralManagerTrans-
portOperations,NewZealandDairyGroup,Hamilton,2000,personnelcommunication).
Ifonlyonetypeofmilkcouldbecollectedduringarun,itwasassumedthatthefull
amount(28,800l)couldbecollectedinoneunit(truckandtrailercombined).Totalvol-
umesofmilkAandmilkBmilktobecollectedwerecheckedforeachstopandifthe
tankerwasempty,thetypewiththegreatervolumewasallocatedfirsttothelargertrailerunit.
Whilecostscanbecalculatedbyseparatingthemintorunning(perkilometrecosts)andhourlycosts,theinformationwasnotreadilyavailableinthisformat,therefore,aflatrate
perkilometrecostwasassumed.Costswereestimatedfromdairy
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