... LLCphysicalandtechnologicalinterestaswell;theclassofsurfacesforwhichana-lyticsolutionstothepotentialtheoryproblem(ofsolvingLaplace’sequation)canbefoundisthusconsiderablyenlarged,beyondthewell-establishedclassofsolutionsobtainedbyseparationofvariables(see,forexample[54]).Sinceitwillbecentraltolaterdevelopments,Sections1.1and1.2brieflydescribetheformofLaplace’sequationinsomeoftheseorthogonalcoordinatesys-tems,andthesolutionsgeneratedbytheclassicalmethodofseparationofvariables.TheformulationofpotentialtheoryforstructureswithedgesisexpoundedinSection1.3.Fortheclassofsurfacesdescribedabove,dual(ormultiple)seriesequationsarisenaturally,asdodual(ormultiple)integralequations.VariousmethodsforsolvingsuchdualseriesequationsaredescribedinSec-tion1.4,includingtheAbelintegraltransformmethodthatisthekeytoolemployedthroughoutthistext.ItexploitsfeaturesofAbel’sintegralequation(describedinSection1.5)andAbel-typeintegralrepresentationsofLegendrepolynomials,Jacobipolynomials,andrelatedhypergeometricfunctions(de-scribedinSection1.6).InthefinalSection(1.7),theequivalenceofthedualseriesapproachandthemoreusualintegralequationapproach(employingsingle-ordouble-layersurfacedensities)topotentialtheoryisdemonstrated.1.1Laplace’sequationincurvilinearcoordinatesThestudyofLaplace’sequationinvariouscoordinatesystemshasalonghistory,generating,amongstotheraspects,manyofthespecialfunctionsofappliedmathematicsandphysics(Besselfunctions,Legendrefunctions,etc.).Inthissectionwegathermaterialofareferencenature;foragreaterdepthofdetail,werefertheinterestedreadertooneofthenumeroustextswrittenonthesetopics,suchas[44],[32]or[74].HereweconsiderLaplace’sequationinthosecoordinatesystemsthatwillbeofconcreteinterestlaterinthisbook;inthesesystemsthemethodofseparationofvariablesisapplicable.Letu1,u2,andu3beasystemofcoor-dinatesinwhichthecoordinatesurfacesu1=constant,u2=constant,andu3=constantaremutuallyorthogonal(i .e. ,intersectorthogonally).Fixapoint(u1,u2,u3)andconsidertheelementaryparallelepipedformedalongthecoordinatesurfaces,asshowninFigure1.1.Thus ... LLCphysicalandtechnologicalinterestaswell;theclassofsurfacesforwhichana-lyticsolutionstothepotentialtheoryproblem(ofsolvingLaplace’sequation)canbefoundisthusconsiderablyenlarged,beyondthewell-establishedclassofsolutionsobtainedbyseparationofvariables(see,forexample[54]).Sinceitwillbecentraltolaterdevelopments,Sections1.1and1.2brieflydescribetheformofLaplace’sequationinsomeoftheseorthogonalcoordinatesys-tems,andthesolutionsgeneratedbytheclassicalmethodofseparationofvariables.TheformulationofpotentialtheoryforstructureswithedgesisexpoundedinSection1.3.Fortheclassofsurfacesdescribedabove,dual(ormultiple)seriesequationsarisenaturally,asdodual(ormultiple)integralequations.VariousmethodsforsolvingsuchdualseriesequationsaredescribedinSec-tion1.4,includingtheAbelintegraltransformmethodthatisthekeytoolemployedthroughoutthistext.ItexploitsfeaturesofAbel’sintegralequation(describedinSection1.5)andAbel-typeintegralrepresentationsofLegendrepolynomials,Jacobipolynomials,andrelatedhypergeometricfunctions(de-scribedinSection1.6).InthefinalSection(1.7),theequivalenceofthedualseriesapproachandthemoreusualintegralequationapproach(employingsingle-ordouble-layersurfacedensities)topotentialtheoryisdemonstrated.1.1Laplace’sequationincurvilinearcoordinatesThestudyofLaplace’sequationinvariouscoordinatesystemshasalonghistory,generating,amongstotheraspects,manyofthespecialfunctionsofappliedmathematicsandphysics(Besselfunctions,Legendrefunctions,etc.).Inthissectionwegathermaterialofareferencenature;foragreaterdepthofdetail,werefertheinterestedreadertooneofthenumeroustextswrittenonthesetopics,suchas[44],[32]or[74].HereweconsiderLaplace’sequationinthosecoordinatesystemsthatwillbeofconcreteinterestlaterinthisbook;inthesesystemsthemethodofseparationofvariablesisapplicable.Letu1,u2,andu3beasystemofcoor-dinatesinwhichthecoordinatesurfacesu1=constant,u2=constant,andu3=constantaremutuallyorthogonal(i .e. ,intersectorthogonally).Fixapoint(u1,u2,u3)andconsidertheelementaryparallelepipedformedalongthecoordinatesurfaces,asshowninFigure1.1.Thus ... LLCAsalreadyindicated,theboundaryconditionsmustbesupplementedbyade-cayconditionatinfinityaswellasfiniteenergyconstraintsnearedges,sothatauniqueandphysicallyrelevantsolutioncanbefound.Sinceedgesintroducedistinctivefeaturesintothetheory,letusdistinguishbetweenclosedsurfaces,thosepossessingnoboundaryoredge,andopenshells,whichhaveoneormoreboundaries.Asphericalsurfaceisclosed,whilstthehemisphericalshellisopenwithacircularboundary.Amoresophisti-cateddistinctioncanbeformulatedintopologicalterms,butthisisunneces-saryforourpurposes.Thesmoothnessofthesurface,includingthepresenceofsingularitiessuchascornersorconicaltips,isimportantinconsideringtheexistenceanduniquenessofsolutions.ThistopichasbeenextensivelyinvestigatedbyKellogg[32].However,thesurfacesunderinvestigationinthisbookareportionsofcoordinatesurfacesasdescribedintheIntroduction,andboththesurfacesandboundingcurvesareanalyticorpiecewiseanalytic.Thesmoothnessconditions,whichmustbeimposedontheclosedoropensurfacesinamoregeneralformulationofpotentialtheory,areautomaticallysatisfiedandwillbeomittedfromfurtherdiscussionexceptfortwocases,theconicalshellsconsideredinChapter6,andthetwo-dimensionalaxially-slottedcylin-dersofarbitrarycross-sectionalprofileconsideredinSection7.5;appropriatesmoothnessconditionsareconsideredintherespectivesections.Thissectionoutlinesgenericaspectsofpotentialtheoryapplicabletobothopen...