Engineering Quarterly Summer 2023

EngineeringQuarterly

WELCOME!

TheEngineeringQuarterlyispublishedfour timeseachyearbythe HammSchoolofEngineeringattheUniversity ofMary.Ineachissue, weincludearticlesfrom eachofthesevenmajorsweoffer:Electrical Engineering,MechanicalEngineering,Civil Engineering,EnvironmentalEngineering, ComputerScience,ConstructionEngineering,andConstructionManagement.TheintendedaudienceoftheEngineeringQuarterly includesengineers,engineeringstudents,engineeringalumni,futureengineeringstudents, andpeopleworkinginrelatedfieldssuchas science,computing,andmathematics.

Inthissummerissuewedescribeourstudentdesignprojectsfromthespringsemester, researchourfacultyareundertaking,newlaboratorymodulesthatwedesignandconstruct overthesummertoimprovetheeducational experienceofourstudents,funsummeractivitiesinwhichweparticipateasfaculty,and someofoureditorialthoughtsonthingslike ArtificialIntelligenceandothercurrentand pastadvancementsthathavebeeninfluenced bycleverengineers.Asusual,wealsoinclude somefungamesandproblemsthatyoumight liketotry.Enjoy!

Dr.TerryPilling

2023SENIOR DESIGN PROJECTS

OnFriday,April22,theSeniorspresented theirdesignprojectsfromProfessorTom Volkman’sSeniorDesigncourse.The projectsthisyearconsistedof: LincolnHighwayProject: DaltonBruce, AidanKelly,TaylorMorrison,andJohn Nauertz MissouriRiverBridge: GabrielBrooks, MaraDalton,PaigeLang,andJonasMitzel I-94/BismarckExpresswayInterchange: JosephFesenmaier,ThomasFreas,Marcus Morehead,ParkerWahl RocketLaunchedUnmannedAerialVehicle: ColeKitzenberg,AbrahamLuedtke, PierreMiller,JohnSammons,JohnSoupir SnowBike: DerekFaul,BenjaminNiemuth, DavidRuiz,andBrettThompson All-TerrainTrackVehicle: NathanDesMarais,JacksonGallagher,MargaretKuhar, andBenPihl

MichaelGorder,whograduatedfromtheUniversityofMaryin2019,hasearnedhislicense asaProfessionalEngineer.Michaeljoined MooreEngineeringaftergraduationandisa ProjectEngineerwiththeirBismarckOffice. WeallenjoyvisitingwithMichaelwhenhe returnstocampusforouralumnieventsand torepresenthiscompanyatthefallandspring careerfairseachyear.Michaelisthefirst graduatefromourengineeringschooltoget hisPElicense.CongratulationsMichael!

Wehaveourseniordesignpresentationsatthe sametimeeachyearasthemeetingofourIndustryAdvisoryBoardsoindustryengineers canattendedthepresentationsandhelpthe facultyjudgethem.AttheHammSchool ofEngineering,ourseniordesignprojects aremultidisciplinaryprojectsinvolvingengineeringstudentsfromdifferentdepartments. Manyprojectsthataredesignedinindustry aremultidisciplinaryonesanditistherefore importantforourstudentstoexperiencethis aspectoftheprocess.Itinvolveslearninghow todelegatethebestengineerforagivenpart ofthedesignandalsohowtocommunicateeffectivelyacrossdisciplines.Italsoallowsour studentstochoosemoreinterestingprojects fortheircapstoneseniordesigncourse.

MICHAEL GORDER,PE

ENR281:SOPHOMORE DESIGN ByANTHONYGARCIA

TheHammSchoolofEngineeringpridesitselfonstudentdesign.Weincorporatedesign projectsaspartofmanyofourcoursesincludingoneswhich,traditionally,donotcontain designprojectsatmostuniversities.Inadditiontothosecourses,wealsohavecourses, fromsophomorethroughtoseniorlevel,that areentirelydesign-based.Thispastsemester oursophomoreENR281studentscompleted theengineeringgroupdesignsthattheybegan inENR280lastsemester.

Eachgrouptaskedwithdesigningremotecontrolcarsandpartsoftheracetrack,including designingbothastaticandadynamicstructure.

Thegoalsofthisprojectwereasfollows:

-designaremotecontrolcarthatsatisfiesthe client’srequirements.

-designadynamicstructurethatsatisfiesthe client’srequirements.

-designastaticstructurethatwillassistin completingtheracetrack.

-makethedesignsasengineering(i.e.mechanical,electrical,energy)efficientandeconomicaspossible.

-remainwithinabudgetof$450tocover manufacturingcostsforprototypesandfinal designs.

-ensurethatallmaterialsaredesignedand fabricated,forexample,studentscannotsimplypurchaseanalreadyfunctioningremote controlcarandmodifyit.

withthetrackandobstaclesspreadthroughouttheentirefloorplanincludingclassrooms, hallways,lobby,anddesigncenter.

Eachteamwasassignedaclient/sponsor whoprovidedspecificationsonthecarand dynamicstructure.Theracecoursewas constructedintheSeniorDesignCenter, theEngineeringFundamentalsclassroom, andtheEngineeringbuildinghallwayand lobby.Coursedeliverablesincludedadetailed projectreport,detaileddesigns,andapresentation.

TheracetookplaceonMonday,April24at 5:30pmintheHammSchoolofEngineering

ProjectReportswererequiredtobeprofessionalanddetailedincluding:

• titlepage

• executivesummary

• tableofcontents

• designproblemandobjectives

• literaturereview/backgroundtheory

• designconceptualization

• initialideas,process,anddecisions

• detaileddesigndocumentationincludingassumptionsmade,functionofthe system,abilitytomeetEngineering Specifications,prototypesdeveloped, testingandresultsrelativetoEngineeringSpecifications

• costanalysis

• manufacturingprocessesused

• humanfactorsconsidered

• alltechnicaldrawings,diagrams,figuresandtables

• laboratorytestplansandresults

• workbreakdownstructure

• scheduling(Ganttchart)

• billofmaterials

• safety

• conclusions

• acknowledgments,references,andappendices

Theracewasexciting,withclients(i.e.professors)requiredtocompleteoneoftherace lapsallontheirownwithoutthehelpofthe students.Intheendateamemergedvictorious.Aftertwosemestersofdesigning,building,testing,andredesigning,victoryissweet fortheteamthatwinsthecompetitioneach year.

ELECTRONIC HOURGLASS ByFINNLEYSOMDAHL

Sophomoreengineering studentFinnleySomdahldesignedanelectronichourglassforfun thissemester.Professor Waldenmaierhadasked himiftherewassome wayhecouldcreatean electronichourglassfor boardgames.Waldenmaierlikestoplayboard gamesbutfindsitannoyingthatthehourglass thatcomeswiththegame andisusedfortimingtheturnsisatraditional onewithsandinit.Theproblemisthatyou can’tadjustthetimethatittakestoempty and,afteroneplayer’sturniscompleted,you havetowaituntilthehourglassemptiesbeforethenextplayercango.Hefiguredan engineeringstudentshouldbeabletodesign anelectronicversionthatsolvestheseproblemsandalsolookscoolatthesametime.

Finnleytookupthechallengeandsolvedthe problemsadmirably.HereisaYouTubevideo ofFinnley’shourglassinaction: https: //youtu.be/f6xpr-_pMvQ

ARTIFICIAL INTELLIGENCE LAB

ByTERRYPILLING

ThissummerIdesignedanewlaboratory moduleformy ENR338:AdvancedEngineeringMathematics coursewhichwillbe incorporatedintothecoursethisfall.Inthe module,thestudentslearntodesignandbuild theirownartificialintelligence.

tobecomeincreasinglyimportanttotoday’s world.Lookingforward,itsimportancewill continuetoincreaseasitispredictedtoadd 4.7trilliondollarstothenation’sGDPbythe year2030.

Wewouldlikeourengineeringstudents tobeontopofthesedevelopmentstoensure thattheycanpursueanycareerstheychoose–eventhosethatrequireexpertiseinneuralnetworksandartificialintelligence.Thefactthat ourgraduatesnotonlyunderstandhowtouse A.I.,butareevenabletowritetheirownneuralnetwork,fromscratch,intheCprogramminglanguage,willplacethematthetopof thepilewhentheyapplyforengineeringpositionsinthisemergingindustry.

MECHANICAL LAB DESIGN

ByANTHONYGARCIA,JAMESCARRICO, ANDDAYAKARLAVADIYA

ThissummertheMechanicalEngineering facultydesignedandconstructedtwonewlaboratoriesforourMechanicalEngineeringprogram.Thesewereathermallaboratoryanda heattransferlaboratory.

largeindustrialpowerplants.Itoperatesby boilingaworkingfluid(mostoftenwater)usingaheatsource,expandingthehigh-pressure steamthroughaturbinetoproducemechanicalwork,condensingofthesteambackinto theliquidphase,andpumpingitbackintothe boilertocompletethecycle.

Theheatinputtotheboilerunitiscontrolledusingthevoltageregulatorattachedto aheatingelement.Thepressureandtemperatureattheinletandoutletoftheboiler andthesteamturbinearerecordedsimultaneously.Theheatreleasedtotheenvironment isdeterminedbymeasuringthetemperature differencebetweentheinletandoutletofthe heatexchangeunit.Thethermalefficiencyis thenevaluatedas

nth =1 qout

qin

Thesecondlaboratoryisaheattransfer laboratoryinwhichtheexperimentaltasksare designedtobeperformedbysenior-levelundergraduatestudentsalongsidethetheorypart oftheir EME474:HeatandMassTransfer course.

ThemodulebeginswithourMechanicalEngineering,ElectricalEngineering,andComputerSciencestudentslearningthecomplex mathematicsinvolvedinneuralnetworksand backpropagation.ThemathematicalmaterialisanaturalcontinuationoftheirCalculus I,II,III,andDifferentialEquationscourses, allofwhichareprerequisitestoENR338. Thestudentsthenwritetheneuralnetwork intheCprogramminglanguageusingknowledgeacquiredintheirENR210andENR304 courses.Afterthenetworkhasbeenwritten, they“train”thenetworkusingtrainingdata thatisfreelyavailableontheinternet.Finally, theytesttheA.I.onnewdataandseehowwell itdoes.

ArtificialIntelligencehascomeintothe publiceyethisyearasaresultoftherelease,andastonishingsuccess,ofOpenAI’s languagemodel,ChatGPT.However,A.I.has beenaroundformanyyearsandcontinues

Thethermallaboratoryfacilitatesahandfulof benchtopexperimentalset-upsthatwillaidin validatingtheapplicationoflawsofthermodynamics.Thelaboratorytasksaredesigned tobeperformedbysenior-levelundergraduatestudentsalongsidethetheorypartoftheir EME441:Thermodynamics-II course.The specificaimsofthelaboratoryinclude

• providinghands-onexperiencetothe studentstoobserve,understandandvalidatethethermodynamiccycleslearned intheclassroom.

• performingacasestudyforenhancing cycleefficiency.

Thespecificaimsofthelaboratoryinclude

• providinghands-onexperiencetothe studentstoobserve,understandandvalidatetheheattransferprincipleslearned intheclassroom

• performingacasestudyresultingindesignrecommendations

Oneexperimentisdesignedtodemonstrate Newton’slawofcoolingandincorporatestwo tasks:

Oneexperimentistodeterminethethermal efficiencyoftheRankineCycle.TheRankine cycleisthevaporpowercycleusedinmost

1. Determinationoftheheattransfer(free convection)fromrectangularfins

2. Determinationoftheeffectofforced convectiononheattransferfromthe heatedrectangularfinsatvaryingairvelocities

Convectionisthemodeofenergytransferbetweenasolidsurfaceandtheadjacentliquidorgasthatisinmotion.Itinvolvesthe combinedeffectsofconductionandadvection.Whilenaturalorfreeconvectioninvolvesfluidmotionoccurringthroughnaturalmeanssuchasthebuoyancyeffect,which manifestsitselfastheriseofwarmerfluidand thefallofthecoolerfluid,theforcedconvectioninvolvestheforcedflowoffluidovera surfacebyexternalmeanssuchasapumpor afan.Thephysicsofconvectionheattransfer overahotsurfaceiscapturedusingNewton’s lawofcoolingexpressedas

Q = hcA (Th T∞)

where hc istheconvectiveheattransfercoefficient, A isthesurfaceareaofthesolidsurface and T∞ istheambienttemperatureofthefluid flowingoverthematerialsurface.

ThefacultyandstaffoftheHammSchoolof Engineeringhadabeachvolleyballteamthis summer!WeplayedeveryThursdaynight, startinginJune,atSertomaParkinBismarck.

TeammembersincludedprofessorsJames Carrico,DayakarLavadiya,TerryPilling, JerikaCleveland,andPatriciaSmithaswell asfriendsandprofessorsfromotherdepartments.Wedidn’twinmanygamesbutwehad alotoffun,exercise,andagreatopportunity toenjoythebeautyoftheparksalongthebank oftheMissouriRiver.

12 m 5 m

Howlongdoestheblocktaketomove from A to B inYolanda’sdesign?

(Z) Zoebuildsatwo-stagetrack.Thefirst stagedrops9metersoverahorizontal runof2meters.Thesecondstagedrops thefinalthreemetersoverahorizontal runofthreemeters.

TheBismarck-Mandanareaisabeautiful,relaxing,andfamily-friendlyplacetospendthe summer,rifewithactivitiesforindividuals andfamiliesofallagegroups.Itreallyisa greatplacetoliveandwork.

BRACHISTOCHRONE PROBLEM ByPATRICKKELLY

9 m

TheprofessorsattheHammSchoolofEngineeringcontinuouslyevaluate,modify,and improveourcoursesandlaboratoriesaswe gatherinputfromindustry,ouralumni,and ourcurrentstudentoutcomes.Thesenewmechanicalengineeringlaboratoriesarepartof thatcontinuousimprovementprocessandwill helpustoremainatthetopinundergraduate engineeringeducation.

Threeengineers,Xavier,Yolanda,andZoe, arecommissionedtodesignatrackwhich willguidea1kilogramblockfrom A to B, asshowninthefiguresbelow,inthe least amountoftime.Theblockstartsfromrest at A andmaynotbepropelledinanyway otherthanbytheforceofgravity.Thetrack ismadeoffrictionlessmaterial.Thevelocity oftheblockasitreaches B isirrelevant.Take ⃗g =10 meterspersecond-squared,directed straightdown.

(X) Xavierbuildsastraighttrackfrom A to B,becausethisistheshortestdistance.

A B

12 m 5 m

Howlongdoestheblocktaketomove from A to B inXavier’sdesign?

(Y) Yolandabuildsatrackwhichdrops12 metersvertically,hasaverysmall curvedsection,andthenruns5meters horizontallyto B,becausetheaverage speedisgreatestinthiscase.

2 m

12 m 5 m

Howlongdoestheblocktaketomove from A to B inZoe’sdesign?

SYNCHRONIZED BALLS PROJECT ByTERRYPILLING

ThereisaYouTubevideothatmadeitsway aroundsocialmedialastyearinwhichaguy wroteacomputerprogramshowinganumber ofballsbouncingbackandforthbetweentwo wallsinasynchronizedfashion.Thewalls wereintheshapeofaVasshowninthepicturebelow:

Whilewatchingthisvideoapersonnaturally assumesthattheballsaremovingaccording tothelawsofphysics,i.e.thattheyfollow projectilemotion.Youmayevenimaginethat youcouldactuallysetupthissituationwith realballsandtheywouldmoveinthefashionshowninthevideo.Infact,itturnsout thattheseballsarenotmovingintheobvious assumedwayand,ifyousetupanactualexperiment,youwouldfindtheydonotsynchronizeastheydointhevideo.Thismakesthe videomuchlessimpressive–sincemuchof theviewers’surpriseandawewhenwatching comesfromtheirbeliefthatthemotionshown ismodelingreality.Instead,YouTubevideos likethisshouldbethoughtofasartprojects

FACULTY SUMMER VOLLEYBALL ByJAMESCARRICO

ratherthanexperimentalsimulationsofreality.

OneoftheprojectsassignedtothesophomorestudentsinmyENR304course,in groupsoftwo,wastowriteaprograminthe CprogramminglanguageandusingOpenGL graphicstotrytorecreatetheresultfrom YouTube.Canyoudoit?

I

S ARTIFICIAL INTELLIGENCEREALLY SMARTERTHANUS

? ByASSALHADDAD

Acontinuous-timeperiodicsignal x(t) is realvaluedandhasafundamentalperiod T = 6.ThenonzeroFourierseriescoefficientsfor x(t) are

ThereisthissceneinTom&Jerrywhere TomischasingJerryintoacirculartube,and heendsupcatchinghisowntailthinkinghe gotJerry.Hepullshistailwithallhismight andhestartstospinendlesslyinsidethattube. What’sannoyingaboutthisspecificsceneis thatmybraineasilysurrendersintobelieving that:yes,thisiswhathappenswhenacatpulls itsowntail.Iamtotallytemptedtobelieve, onasubconsciouslevel,thatTomshouldbe hilariouslyspinningincircles,whileaccordingtophysicsheshouldbestaticand,maybe, pulloffahandfulofhairfromhistail;asimplefreebodydiagramonTomshowsnoexternalforcewhichmeansnorotationorany actualdisplacementshouldoccur.Thisscene revealshowhumanmindsenjoyandgetentertainedbeingfooledintobelievingamoredramaticscenariothantheactualboringone.We chosefictionoverrealitybecauseitismore fun.

Wedothiseveryminute.Wearereally goodindoingthis,orweareveryluckyto beableto“do”this,orevenfor“this”tobe donetous.Wehavebeenaccumulatingthose littledropletsofcreativitysincethedawnof time.Ithappenssooftenthatwedon’teven realizethatitishappeninguntillater.Itis socommoninourspeciesthatwecan’tfind twohumansthatthinkorfeelexactlythesame way.Allthroughthehistoryoflearning,there wasalwaysamomentofvisionjustbefore thatlearningmoment;therewasasmallexplosionthatleadtolearningnewstuff.AIcan definitelylearnfasterthanus,butitlacksthat motivationtolearn.

ColinWilson’sentireworkwasbasically aonebiginvestigationintothosehistorical momentswhereonehumanaccidentallyconnectedtotheexternalenergyoftheuniverse. Inthatcontexthegoesonsayingthataspider isthegreatestengineerofourtime,butitonly buildsitshomebasedonapre-programmed code.Itisunabletovisualizeitswebbefore goingoutandbuildingit.Itissomethingthat thedumbestcarpenteronearthcando;visualizesomethingthatdoesn’texist...yet.

KenKen(similarbutslightlydifferent from‘KenDoku’)isastyleofarithmeticlogic puzzleinventedin2004byJapanesemath teacherTetsuyaMiyamoto.KenKenderives fromtheJapanesewordforcleverness.As inSudoku,thegoalofeachpuzzleistofill agridwithdigits––1through4fora 4 × 4 grid,1through5fora 5 × 5,1through6fora 6 × 6,etc.––sothatnodigitappearsmore thanonceinanyroworanycolumn.The gridsaredividedintoheavilyoutlinedgroups ofcellscalledcagesandthenumbersinthe cellsofeachcagemustproduceacertain‘target’numberwhencombinedusingthespecifiedmathematicaloperation.Digitsmaybe repeatedwithinacage,aslongastheyarenot inthesameroworcolumn.Single-cellcage isafreespace.

HereisyourKenKenchallengeforthisissueof EngineeringQuarterly.Ihopeyouenjoysolvingit.Thesolutioncanbefoundat theendoftheissue.

ItistemptingtobelievethatAIisgoing toevolvebeyondus;recreatingthecreation story.Butactuallynomatterhowsmartit gets,wewillalwaysbesmarter.Nowitcould bestronger,faster,moreaccurate,evenmore suitabletosurvive;butthat’snotsmarter.It couldactuallycompletelyannihilateourrace, butstillitwon’tbesmarterthanus.Itcan onlyripahandfulofhairfromthebiguniversesoul,butitwon’tmoveaninchinany direction,becauseitisbasedinusandonly us.Wemove,itmoves.Westop,itstops, andifwedie,itdies.Icanimaginein200 yearsAIwillbesoaccurateinsimulatingmy current-2023humanitythatIwon’tbeableto tellthedifference.Butchildrenbornin200 yearswon’tbefooledbecausetheywillbe smarterthanmerightnowandtheywilleasily detectdigitalfacsimilesofhumanbehavior.

Irealizethatwehumansarealsoguiltyof theimitationsinallthetime.Whenatoddler istalking,heisbasicallytryingtoimitatehis parentsandsiblings.Thetoddlerhasnoidea whathewantstosay.Iseethisincreative artisticworkallthetime.Wearealltrying tochannelaheroofourswhetherconsciously orsubconsciously.Butitisimitating,orat itsbest,itisadeepunderstandingofthecreativealgorithmofourfavoriteartist.Wesee moviestryingtobeaPulpFictionlookalike, orsomemusiciantryingtoactorsoundlike MilesDavis...weseethisallthetime.But that’snotallthatwedo.

Ineveryiteration,ineverycycleofimitation,somethinghappens.Aspark,avision, avoice,afuzzyfeeling,thatallofasudden elevatesustoanewlevelofexistence.AI canonlymoveinclosedcircles.Wemove inupwardspirals.Duringthatspiralrisewe capturesomethingelsefromtheuniversethat isn’tours.Something“external”.Weaccumulateandincorporatesomemassthatisnot humanintoourhumanminds.Weaccumulate allkindsofstuff;smell,sounds,chemicals, breezeofair,color,etc.Itisveryrandomand youcanneverexpectwhatyou’regoingtoget. Butmostimportant,itisnotofahumanorigin“yet”.Itwillsoonbeafterdigestingthat moment.

AUDITORY PROCESSING ByNANCYKELLY

Oneofthesimplestmusicalinstruments isasmallopen-toppedboxwithrubberbands stretchedacrosstheopening.Whenplucked orstruck,arubberbandwillvibrateataspecificfrequencythatdependsonitscomposition,length,width,thickness,anddegreeof tension.Takingadvantageofthisdependence, whichisevidentincertainflexiblematerials, atypicalstringedmusicalinstrumentincludes severalsuchstrings,chosenandtunedtovibrateatselectedfrequencies.

Anaturalstructurethatcanvibrateinthis manneristhebasilarmembrane,whichis founddeepinsidethemammalianear.The basilarmembraneiscomposedoffibroustissuewhosemassandstiffnessbothchange graduallyoveritslength.Thismembranelies withinthecochlea,asnail-shapedbonyspiralcanallocatedintheinnerear.Toproduce thesensationofhearing,soundvibrationsare transmittedtothecochleaandtransducedinto electricalactivityalongthebasilarmembrane. Thismembraneisatonotopicorgan, whichmeansthatitsresponsetosound vibrationsisbothfrequencyandlocationdependent.Forexample,forhighfrequencies, thebasilarmembranevibratesclosetotheentranceofthecochlea,whileforlowfrequencies,itvibratesattheotherend,towardsthe

EEL314:SIGNALS &SYSTEMS PROBLEM ByNANCYKELLY

KENKEN PUZZLE ByNANCYKELLY

openingatthetopofthecochlea.ThefrequencymappingisshownintheaboveFigure.Consequently,thebasilarmembrane’svibrationsdecomposeasoundintosinusoidsof varyingamplitudesandfrequenciesasdifferentregionsofthemembranerespondtodifferentfrequencyranges.Thesesoundcomponentsaremappedtocorrespondinglocations intheprimaryauditorycortexofthebrain, wheretheyarefurtherprocessedandinterpreted.

Theresonancebehaviorofthebasilar membranecanbemodeledasanarrayofoverlappingbandpassfilters,calledauditoryfilters.Anexampleofsuchafilterbankis shownintheFigurebelow,althoughconsiderablymorefilterswouldbeneededtoaccuratelymodelthemembrane’sbehavior.However,filterbandwidthsdoincreaseascenter frequencyincreases,whichindicatesthatthe decompositionismorespecificatlowerfrequencies.

Whilereflectingonthepandemicandonthe hugeglobalresponsefromthemedicaland engineeringcommunity:tobuildtemporary medicalfacilities,manufacturingfacilitiesfor masksandmedicaldevices,tocareforthe ill,andtodevelopavaccine,Ithoughtabout manyothertimesinthepastwhenthenation’s engineers,medicalprofessionals,andpoliticians,haveworkedtogether,onavastscale, forthesakeofthenation’spublichealth.

InthisarticleIdecidedtochooseoneexamplethathasimprovedthelivesofalmost allofusbutis,perhaps,notwellknownto many–thefluoridationofthenation’spublic watersupply.Waterfluoridationhasbeenin thenewslatelyafteritwasdiscoveredthatthe CityofBuffalo,NewYork,stoppedadding fluoridetoitswaterin2015causingresidents, in2023,toinstigateaclassactionlawsuit againstthecity.

Fluoridationofpublicwatersuppliesbeganinthemid-20thcenturyasapublichealth measuretopreventtoothdecay.Thehistory ofthispracticeiscomplex,andinvolvesboth scientificandpoliticalelements.

whereawaterpipelinefromawarmsprings hadbeenintroducedrecently.Furtherstudiesinothercommunities,includingBauxite, Arkansas,confirmedthatthewaterwasthe sourceoftheproblem.

Finally,in1931,thespecificcauseofthe stainingwasidentifiedasfluoridebyDr.H. TrendleyDeanandhisteamattheNational InstituteofHealth,whousednewlydeveloped methodstomeasurethefluoridecontentof watersamples.

DeantheninitiatedstudiesacrosstheU.S. andfoundacorrelationbetweenfluoridelevelsinwateranddentalcaries(cavities).Based onthesefindings,Deanhypothesizedthata certainleveloffluoridewouldprovidethe benefitsofcavitypreventionwithoutcausing fluorosis.

Theresonancerangeofthebasilarmembraneinthehumanearisapproximately2020,000Hz,and,ascanbeseenfromtheFigure,filteringismoreprecisebelow5000Hz. Almostallenergyinhumanspeechsounds canbefoundatfrequenciesbelowthisthreshold,whichindicatesthatspeechproduction andhumanauditoryprocessingarehighlycoordinated.

Thisleadstothequestion:didhuman speechdevelopinsuchawayastobemore readilyprocessedbylisteners,orwasitthe otherwayaround?Giventhatthearticulators usedtoproducehumanspeecharesoflexible andsoreadilycontrolledbytheirusers,while theauditoryfunctionoftheinnerearisgenerallyinaccessible,theanswerislikelythat humanbeingsadjustedtheirwayofspeaking toaccommodatethecharacteristicsoftheauditoryprocessingsystem.

ENGINEERING PUBLIC HEALTH ByTERRYPILLING

TheCOVID-19viralpandemichasbeen declaredofficiallyoverinastatementmade bytheCentersforDiseaseControlandPreventiononMay05,2023:

May11,2023,markstheendof thefederalCOVID-19PHEdeclaration.Afterthisdate,CDC’s authorizationstocollectcertain typesofpublichealthdatawill expire.TheUnitedStateshas mobilizedandsustainedahistoricresponsetotheCOVID-19 pandemic.Asanation,wenow findourselvesatadifferentpoint inthepandemic–withmoretools andresourcesthaneverbeforeto betterprotectourselvesandour communities.

Thefirsthintthatfluoridemightbebeneficialfordentalhealthcamefromobservationalstudiesintheearly20thcentury.Dentistsnoticedthatpeoplewholivedinareas withnaturallyhighlevelsoffluorideintheir waterhadfewercavitiesthanpeopleinareas withlowlevelsoffluoride.Thisledtoaseriesofstudiesthatshowedaclearcorrelation betweenfluorideconcentrationinwaterand dentalhealth.

Dr.FrederickMcKay(1874-1959)was oneofthefirsttoobservethecorrelationbetweenfluorideandfewercavities.McKaywas bornonMarch12,1874,inOntario,Canada, andhemovedtotheUnitedStatestostudy dentistryattheUniversityofPennsylvania. Aftergraduatingin1898,hemovedtoColoradoSprings,Colorado,toopenadental practice.

Shortlyafterstartinghispractice,McKay noticedahighprevalenceofbrownstains (nowknownasdentalfluorosis)ontheteeth ofhispatients.However,healsoobservedthat despitethediscoloration,theaffectedteeth weresurprisinglyresistanttodecay.Curious aboutthisphenomenon,McKaybeganinvestigatingthecause.

Overthenextthreedecades,McKay andhiscolleaguesstudiedthiscondition, whichtheycalled“ColoradoBrownStain.” Theyinitiallysuspectedthatthestainingwas causedbyfactorssuchaspoornutrition,overconsumptionofporkormilk,orevenoveruse oflocallyminedleadandcopper.

In1909,McKaysharedhisfindingsata meetingofdentalprofessionalsinColorado. HispresentationwasheardbyDr.Green VardimanBlack,whowasaleadingdentalresearcheratthetimeandisoftenreferredtoas thefatherofmoderndentistry.BlackwasintriguedbyMcKay’sobservationsandagreed toworkwithhimtoinvestigatethecauseof theColoradoBrownStain.

McKayandBlack,bythe1920s,hadbeguntosuspectthatsomethinginthelocalwatersupplywasresponsibleforthestains.In 1923,theyfoundevidencetosupportthishypothesiswhenMcKaylearnedofasimilar conditionaffectingresidentsofOakley,Idaho,

Thefirsttrialsofwaterfluoridationwere conductedinthemid-1940sinGrandRapids, Michigan.Beforeinitiatingthetrials,researchersspentseveralyearscollectingbaselinedataonthedentalhealthofthecity’sresidents.TheresultsoftheGrandRapidstrial wereoverwhelminglypositive:toothdecay ratesdroppedsignificantlyinthecity,especiallyamongchildren.

Followingthesesuccessfultrials,other citiesbegantofluoridatetheirwater,andthe practicesoonspreadacrosstheUnitedStates. TheU.S.PublicHealthServiceofficiallyendorsedwaterfluoridationin1950.

Throughoutitshistory,waterfluoridation hassparkedcontroversiesinasimilarfashiontotheonesweobservedsurroundingtesting,masks,vaccines,etc.duringtheCOVID19pandemic.Withfluoridation,criticsraised concernsabouttheethicsofmassmedication, thepotentialforadversehealtheffects,and thereliabilityoftheearlystudiesthatsupportedfluoridation.Somepeoplewerealso simplyuncomfortablewiththeideaofadding chemicalstothepublicwatersupply.

Thehistoryofwaterfluoridationprovides aclearexampleofhowscientificresearchcan betranslatedintopublichealthpolicy.Italso highlightsthechallengesthatcanarisewhen implementingsuchpolicies.Despiteitscontroversialnature,thefluoridationofpublic watersupplieshasledtosignificantimprovementsindentalhealth,particularlyincommunitieswithpooraccesstodentalcare.

Engineersandengineeringcompanies haveplayed,andcontinuetoplay,animportantroleintheprocessofwaterfluoridation. Waterfluoridationrequirescarefulplanning, design,andexecutiontoensurethattheright amountoffluorideisaddedtothewatersupplyconsistentlyandsafely.Severaldifferent systemscanbeusedtoaddfluoridetoawater supply,includingdryadditivefeedsystems, liquidadditivefeedsystems,andsystemsthat usefluorosilicicacid.Eachofthesesystems mustbecarefullydesigned,built,andmaintainedtoensureitoperatesproperlyandengineeringcompaniesoftenworkcloselywith municipalwaterauthoritiestodesignandimplementthesesystems.

Fluorideadditivesusedforwaterfluoridationarederivedfromphosphaterock.This rockisminedandthenprocessedtomake manydifferentproducts,includingfertilizers,animalfeeds,andvariouschemicalsused inindustrialprocesses.Duringtheprocess

ofmakingphosphatefertilizers,phosphate rockistreatedwithsulfuricacidtoproduce phosphoricacid.Thisprocessalsocreates abyproductgascalledsilicontetrafluoride. Thisgasiscapturedandtreatedwithwatertoproducealiquidproductcalledfluorosilicicacidwhichisoneofthemostcommonlyusedadditivesforwaterfluoridation.It isshippedinliquidformtowatertreatment plants,whereitisaddedtothewatersupply insmallamounts.

Allofthesefluoridecompoundsarevery carefullypurifiedandprocessedtoremove impurities.Theyhavetomeetstrictquality standardssetbytheAmericanWaterWorks AssociationandtheNationalSanitationFoundation,whichrequirethatfluorideadditives donotcontaincontaminantsatlevelsthat couldposearisktohealth.Thesestandards areenforcedbytheU.S.EnvironmentalProtectionAgency.

Inadditiontothepracticalaspectsofwaterfluoridation,engineersandengineering companiesarealsoinvolvedinresearching anddevelopingnewtechnologiesandmethodsforfluoridation.Thisinvolvestesting differenttypesofadditives,developingnew typesoffeedsystems,andstudyingtheimpactsoffluoridationonvariousaspectsofthe watersupplysystem.

Massivepublichealthprojectsthatimprovethelivesofeveryonehaveoccurred sincethefoundingofthecountryandwill continuetooccurasadvancesaremadein science,engineering,andmedicaltechnology. Sometimes,aswasthecaseduringthepandemic,theengineering,medical,andpolitical responseisrapidandhighlypublicized.Other timestheresponseisslow,measured,andnot aswellknowntothegeneralpublic.Thelongtermresult,ideally,isthesameinbothcases–ahealthierenvironmentforthenationandits futuregenerations.

BRACHISTOCHRONE SOLUTION

Thefollowingarethethreetimes:

(Xavier) 1 678s

(Yolanda) 1 872s

(Zoe) 1 668s

Notethattheoptimalshapeforsuchatrack wasdeterminedbyJ.Bernoulliin1696!

synch.c

//Compile: //gccsynch.c-lGL-lGLU-lglut-lm

#include <GL/gl.h>

#include <GL/glu.h>

#include <GL/glut.h>

#include <stdio.h>

#include <math.h>

#include <unistd.h>

#define Lx800

#define Ly800

#define NUM16

#define SIDES40

#define RADIUS30

#define PI3.1415927

#define dt0.01

int count=0; double t=0,R[NUM],T[NUM],X[NUM],Y[NUM], V[NUM],V0[NUM], red[10]=

{0.0,0.0,0.0,0.0,0.0,0.0,0.5,1.0,1.0,1.0}, green[10]=

{0.0,0.0,0.5,1.0,1.0,1.0,1.0,1.0,0.5,0.0}, blue[10]= {0.5,1.0,1.0,1.0,0.5,0.0,0.0,0.0,0.0,0.0};

void Initialize(void); void display(void);

void draw_walls(void); void connect_balls(void);

void draw_ball(int, double, double); void move_ball(void);

void keys(unsignedchar, int, int);

int main(int argc, char *argv[]){ glutInit(&argc,argv); glutInitDisplayMode(GLUT_DOUBLE| GLUT_RGB); glutInitWindowPosition(200,10); glutInitWindowSize(1000,600); glutCreateWindow("Synchronized"); glutDisplayFunc(display); glutKeyboardFunc(keys); Initialize(); glutMainLoop(); return 0; } void Initialize(void){ glClearColor(0.0,0.0,0.0,0.0); gluOrtho2D(-Lx,Lx,0,Ly); for (int k=0;k<NUM;k++){

R[k]=300.0+20.0*k; V0[k]=R[k]/10000.0; V[k]=V0[k];

T[k]=3.0*PI/4.0; X[k]=R[k]*cos(T[k]); Y[k]=R[k]*sin(T[k]); }

} void move_ball(void){ //thetimelooptellshowmanytime //stepsbetweeneachnewdisplay for (float t=0;t<60*dt;t+=dt){ for (int k=0;k<NUM;k++){

T[k]+=V[k]*dt; //reflectonrightboundary if(T[k]<PI/4.0){ //resettooriginalVtosynch V[k]=V0[k]; //resettosamethetaonopposite //sideofwalltokeepthetiming T[k]=PI/2.0-T[k];

} //reflectonleftboundary if(T[k]>3*PI/4.0){ count++; if (count==23*NUM)sleep(5); //resettooriginalVtosynch V[k]=-V0[k]; //resettosamethetaonopposite //sideofwalltokeepthetiming T[k]=3.0*PI/2.0-T[k]; } X[k]=R[k]*cos(T[k]); Y[k]=R[k]*sin(T[k]);

}

S

Thefollowingisthecodefromoneofthe studentsolutions.

}

} void display(void){ glClear(GL_COLOR_BUFFER_BIT); draw_walls(); connect_balls(); for (int k=0;k<NUM;k++) draw_ball(k,X[k],Y[k]); move_ball(); glutSwapBuffers(); glutPostRedisplay();

} void draw_walls(void){ glColor3f(1.0,0.0,0.0); glBegin(GL_LINES); glVertex2f(-0.75*Lx,0.75*Lx); glVertex2f(0,0); glVertex2f(0,0); glVertex2f(0.75*Lx,0.75*Lx); glEnd();

} void draw_ball(int k, double x, double y){

glColor3f(red[k%10],green[k%10],blue[k %10]);

glLineWidth(5.0);

glEnable(GL_LINE_SMOOTH); glBegin(GL_LINES); for(int i=0;i<=SIDES;i++){

glVertex2f(x,y);

glVertex2f( x+RADIUS*cos(2*PI*i/SIDES), y+RADIUS*sin(2*PI*i/SIDES) );

} glEnd();

} void connect_balls(void){ glColor3f(1.0,1.0,1.0); glEnable(GL_LINE_SMOOTH); glLineWidth(2.0);

glBegin(GL_LINES); for(int k=0;k<(NUM-1);k++){ glVertex2f(X[k],Y[k]); glVertex2f(X[k+1],Y[k+1]);

} glEnd(); } void keys(unsignedchar key, int x, int y){ switch(key){ case ’q’:exit(0); default: break; } }

Thecodeworkstoreproducethemotionjust liketheYouTubevideobut,asyoucansee, itisnotmodelingreality.Insteaditisdesignedtoproducethesynchronizedeffect. Thestudentsalsowrotesimilarsimulations usingthelawsofprojectilemotionandfound thatthesynchronizedeffectdoesnotoccur exceptinverycontrivedsituations.Perhaps youcanfindacollectionofinitialheights, initialvelocities,andaparticularboundary shapewhichwillproducesynchronizedmotionwhileremainingwithintheconstraints ofreality(i.e.withoutviolatingthelawsof physics)?

IGNALS &SYSTEMS SOLUTION

SYNCHRONIZED BALLS SOLUTION