文献翻译——用于侧向导航仪器：指南针

第1页外文文献资料Thedirectionfindinginstrumentusedinnavigation：Compass1.TypesofcompassesTherearetwowidelyusedandradicallydifferenttypesofcompass.Themagneticcompasscontainsamagnetthatinteractswiththeearthsmagneticfieldandalignsitselftopointtothemagneticpoles.6Simplecompassesofthistypeshowdirectionsinaframeofreferenceinwhichthedirectionsofthemagneticpolesareduenorthandsouth.Thesedirectionsarecalledmagneticnorthandmagneticsouth.Thegyrocompass(sometimesspelledwithahyphen,orasoneword)containsarapidlyspinningwheelwhoserotationinteractsdynamicallywiththerotationoftheearthsoastomakethewheelprecess,losingenergytofrictionuntilitsaxisofrotationisparallelwiththeearths.Thewheelsaxisthereforepointstotheearthsrotationalpoles,andaframeofreferenceisusedinwhichthedirectionsoftherotationalpolesareduenorthandsouth.Thesedirectionsarecalledtruenorthandtruesouth,respectively.Thereareotherdeviceswhicharenotconventionallycalledcompassesbutwhichdoallowthetruecardinaldirectionstobedetermined.Theyaresaidtoworklikeacompass,orasacompass,withoutactuallybeingacompass.Forexample,aGlobalPositioningSystem(GPS)satellitereceiverdeterminesitsownpositionontheground,astruelatitudeandtruelongitude.Ifthereceiverisbeingmoved,evenatwalkingpace,itcanfollowthechangeofitsposition,andhencedeterminethecompassbearingofitsdirectionofmovement,andthencethedirectionsofthecardinalpointsrelativetoitsdirectionofmovement.SomeGPSreceivershavetwoantennas,fixedsomedistanceaparttothestructureofavehicle,usuallyanaircraft.Theexactlatitudesandlongitudesoftheantennascanbedeterminedsimultaneously,whichallowsthedirectionsofthecardinalpointstobecalculatedrelative第2页totheheadingoftheaircraft(thedirectioninwhichitsnoseispointing),ratherthantoitsdirectionofmovement,whichwillbedifferentifthereisacrosswind.AmucholderexamplewastheChinesesouth-pointingchariot,whichworkedlikeacompassbydirectionaldeadreckoning.Itwasinitializedbyhand,possiblyusingastronomicalobservationse.g.ofthePoleStar,andthenceforthcounteractedeveryturnthatwasmadetokeepitspointeraiminginthedesireddirection,usuallytothesouth.Theearthsmagneticpolesdonotcoincidewiththerotationalpoles,andthepositionsofthemagneticpoleschangeovertimeonatime-scalethatisnotextremelylongbyhumanstandards.Significantmovementshappeninafewyears.(Overmillionsofyears,thedirectionsofthetruepolesalsoshift,becauseofcontinentaldrift.)Foranobserveratanypointontheearthssurface,thereisanangle,calledthemagneticdeclination(ormagneticvariation),betweenthedirectionsofmagneticnorthandtruenorth.Themagneticdeclinationisdifferentatdifferentpointsontheearth,andchangeswithtime.Closetotheequator,themagneticdeclinationisnomorethanafewdegrees,butinarcticandAntarcticlatitudesitcanbemuchgreater.Somemagneticcompassesincludemeanstocompensateforthemagneticdeclination,sothatthecompassshowstruedirections,relativetotheearthsrotationalpoles.Theuserofsuchacompasshastoknowthelocalvalueofthemagneticdeclination,andadjustthecompassaccordingly.2.MagneticcompassThemagneticcompassconsistsofamagnetizedpointer(usuallymarkedontheNorthend)freetoalignitselfwithEarthsmagneticfield.Acompassisanymagneticallysensitivedevicecapableofindicatingthedirectionofthemagneticnorthofaplanetsmagnetosphere.Thefaceofthecompassgenerallyhighlightsthecardinalpointsofnorth,south,eastandwest.Often,compassesarebuiltasastandalonesealedinstrumentwithamagnetizedbarorneedleturningfreelyuponapivot,ormovinginafluid,thusabletopointinanortherlyandsoutherlydirection.Thecompassgreatlyimprovedthesafetyandefficiencyoftravel,第3页especiallyoceantravel.Acompasscanbeusedtocalculateheading,usedwithasextanttocalculatelatitude,andwithamarinechronometertocalculatelongitude.ItthusprovidesamuchimprovednavigationalcapabilitythathasonlybeenrecentlysupplantedbymoderndevicessuchastheGlobalPositioningSystem(GPS).ThecompasswasinventedduringtheChineseHanDynastybetweenthe2ndcenturyBCand1stcenturyAD.1ThedrycompasswasinventedinmedievalEuropearound1300.4Thiswassupplantedintheearly20thcenturybytheliquid-filledmagneticcompass.5Other,moreaccuratedeviceshavebeeninventedfordeterminingnorththatdonotdependontheEarthsmagneticfieldforoperation(knowninsuchcasesastruenorth,asopposedtomagneticnorth).Agyrocompassorastrocompasscanbeusedtofindtruenorth,whilebeingunaffectedbystraymagneticfields,nearbyelectricalpowercircuitsornearbymassesofferrousmetals.Arecentdevelopmentistheelectroniccompass,eitheramagnetometerorafibreopticgyrocompass,whichdetectsthemagneticdirectionswithoutpotentiallyfalliblemovingparts.Amagnetometerfrequentlyappearsasanoptionalsubsystembuiltintohand-heldGPSreceivers.However,magneticcompassesremainpopular,especiallyinremoteareas,astheyarerelativelyinexpensive,durable,andrequirenopowersupply.7HowamagneticcompassworksAcompassfunctionsasapointertomagneticnorthbecausethemagnetizedneedleatitsheartalignsitselfwiththelinesoftheEarthsmagneticfield.Themagneticfieldexertsatorqueontheneedle,pullingoneendorpoleoftheneedletowardtheEarthsNorthmagneticpole,andtheothertowardtheSouthmagneticpole.Theneedleismountedonalow-frictionpivotpoint,inbettercompassesajewelbearing,soitcanturneasily.Whenthecompassisheldlevel,theneedleturnsuntil,afterafewsecondstoallowoscillationstodieout,oneendpointstowardtheNorthmagneticpole.AmagnetorcompassneedlesnorthpoleisdefinedastheonewhichisattractedtotheNorthmagneticpoleoftheEarth,innorthernCanada.Sinceoppositepolesattract(northtosouth)theNorthmagneticpoleoftheEarthisactuallythesouthpoleoftheEarthsmagneticfield.8910The第4页compassneedlesnorthpoleisalwaysmarkedinsomeway:withadistinctivecolor,luminouspaint,oranarrowhead.Insteadofaneedle,professionalcompassesusuallyhavebarmagnetsgluedtotheundersideofadiskpivotedinthecentersoitcanturn,calledacompasscard,withthecardinalpointsanddegreesmarkedonit.Bettercompassesareliquid-filled;thechambercontainingtheneedleordiskisfilledwithaliquidwhosepurposeistodamptheoscillationsoftheneedlesoitwillsettledowntopointtoNorthmorequickly,andalsotoprotecttheneedleordiskfromshock.Innavigation,directionsonmapsareexpressedwithreferencetogeographicalortruenorth,thedirectiontowardtheGeographicalNorthPole,therotationaxisoftheEarth.SincetheEarthsmagneticpolesarenear,butarenotatthesamelocationsasitsgeographicpoles,acompassdoesnotpointtotruenorth.Thedirectionacompasspointsiscalledmagneticnorth,thedirectionoftheNorthmagneticpole,locatedinnortheasternCanada.DependingonwherethecompassislocatedonthesurfaceoftheEarththeanglebetweentruenorthandmagneticnorth,calledmagneticdeclinationcanvarywidely,increasingthefartheroneisfromtheprimemeridianoftheEarthsmagneticfield.Thelocalmagneticdeclinationisgivenonmostmaps,toallowthemaptobeorientedwithacompassparalleltotruenorth.Ingeographicregionsnearthemagneticpoles,innortheasternCanadaandAntarctica,variationsintheEarthsmagneticfieldcausemagneticcompassestohavesuchlargeerrorsthattheyareuseless,sootherinstrumentsmustbeusedfornavigation.3.HowamagneticcompassworksAcompassfunctionsasapointertomagneticnorthbecausethemagnetizedneedleatitsheartalignsitselfwiththelinesoftheEarthsmagneticfield.Themagneticfieldexertsatorqueontheneedle,pullingoneendorpoleoftheneedletowardtheEarthsNorthmagneticpole,andtheothertowardtheSouthmagneticpole.Theneedleismountedonalow-frictionpivotpoint,inbettercompassesajewelbearing,soitcanturneasily.When第5页thecompassisheldlevel,theneedleturnsuntil,afterafewsecondstoallowoscillationstodieout,oneendpointstowardtheNorthmagneticpole.AmagnetorcompassneedlesnorthpoleisdefinedastheonewhichisattractedtotheNorthmagneticpoleoftheEarth,innorthernCanada.Sinceoppositepolesattract(northtosouth)theNorthmagneticpoleoftheEarthisactuallythesouthpoleoftheEarthsmagneticfield.8910Thecompassneedlesnorthpoleisalwaysmarkedinsomeway:withadistinctivecolor,luminouspaint,oranarrowhead.Insteadofaneedle,professionalcompassesusuallyhavebarmagnetsgluedtotheundersideofadiskpivotedinthecentersoitcanturn,calledacompasscard,withthecardinalpointsanddegreesmarkedonit.Bettercompassesareliquid-filled;thechambercontainingtheneedleordiskisfilledwithaliquidwhosepurposeistodamptheoscillationsoftheneedlesoitwillsettledowntopointtoNorthmorequickly,andalsotoprotecttheneedleordiskfromshock.Innavigation,directionsonmapsareexpressedwithreferencetogeographicalortruenorth,thedirectiontowardtheGeographicalNorthPole,therotationaxisoftheEarth.SincetheEarthsmagneticpolesarenear,butarenotatthesamelocationsasitsgeographicpoles,acompassdoesnotpointtotruenorth.Thedirectionacompasspointsiscalledmagneticnorth,thedirectionoftheNorthmagneticpole,locatedinnortheasternCanada.DependingonwherethecompassislocatedonthesurfaceoftheEarththeanglebetweentruenorthandmagneticnorth,calledmagneticdeclinationcanvarywidely,increasingthefartheroneisfromtheprimemeridianoftheEarthsmagneticfield.Thelocalmagneticdeclinationisgivenonmostmaps,toallowthemaptobeorientedwithacompassparalleltotruenorth.Ingeographicregionsnearthemagneticpoles,innortheasternCanadaandAntarctica,variationsintheEarthsmagneticfieldcausemagneticcompassestohavesuchlargeerrorsthattheyareuseless,sootherinstrumentsmustbeusedfornavigation.第6页4.UsingacompassTurningthecompassscaleonthemap(D-thelocalmagneticdeclination)Whentheneedleisalignedwithandsuperimposedovertheoutlinedorientingarrowonthebottomofthecapsule,thedegreefigureonthecompassringatthedirection-of-travel(DOT)indicatorgivesthemagneticbearingtothetarget(mountain).Amagneticcompasspointstomagneticnorthpole,whichisapproximately1,000milesfromthetruegeographicNorthPole.AmagneticcompasssusercandeterminetrueNorthbyfindingthemagneticnorthandthencorrectingforvariationanddeviation.Variationisdefinedastheanglebetweenthedirectionoftrue(geographic)northandthedirectionofthemeridianbetweenthemagneticpoles.Variationvaluesformostoftheoceanshadbeencalculatedandpublishedby1914.92Deviationreferstotheresponseofthecompasstolocalmagneticfieldscausedbythepresenceofironandelectriccurrents;onecanpartlycompensateforthesebycarefullocationofthecompassandtheplacementofcompensatingmagnetsunderthecompassitself.Marinershavelongknownthatthesemeasuresdonotcompletelycanceldeviation;hence,theyperformedanadditionalstepbymeasuringthecompassbearingofalandmarkwithaknownmagneticbearing.Theythenpointedtheirshiptothenextcompasspointandmeasuredagain,graphingtheirresults.Inthisway,correctiontablescouldbecreated,whichwouldbeconsultedwhencompasseswereusedwhentravelinginthoselocations.Marinersareconcernedaboutveryaccuratemeasurements;however,casualusersneednotbeconcernedwithdifferencesbetweenmagneticandtrueNorth.Exceptinareasofextrememagneticdeclinationvariance(20degreesormore),thisisenoughtoprotectfromwalkinginasubstantiallydifferentdirectionthanexpectedovershortdistances,providedtheterrainisfairlyflatandvisibilityisnotimpaired.Bycarefullyrecordingdistances(timeorpaces)andmagneticbearingstraveled,onecanplotacourseandreturntoonesstartingpointusingthecompassalone.83Soldierusingaprismaticcompasstogetanazimuth.Compassnavigationinconjunctionwithamap(terrainassociation)第7页requiresadifferentmethod.Totakeamapbearingortruebearing(abearingtakeninreferencetotrue,notmagneticnorth)toadestinationwithaprotractorcompass,theedgeofthecompassisplacedonthemapsothatitconnectsthecurrentlocationwiththedesireddestination(somesourcesrecommendphysicallydrawingaline).Theorientinglinesinthebaseofthecompassdialarethenrotatedtoalignwithactualortruenorthbyaligningthemwithamarkedlineoflongitude(ortheverticalmarginofthemap),ignoringthecompassneedleentirely.83Theresultingtruebearingormapbearingmaythenbereadatthedegreeindicatorordirection-of-travel(DOT)line,whichmaybefollowedasanazimuth(course)tothedestination.Ifamagneticnorthbearingorcompassbearingisdesired,thecompassmustbeadjustedbytheamountofmagneticdeclinationbeforeusingthebearingsothatbothmapandcompassareinagreement.83Inthegivenexample,thelargemountaininthesecondphotowasselectedasthetargetdestinationonthemap.Somecompassesallowthescaletobeadjustedtocompensateforthelocalmagneticdeclination;ifadjustedcorrectly,thecompasswillgivethetruebearinginsteadofthemagneticbearing.Themodernhand-heldprotractorcompassalwayshasanadditionaldirection-of-travel(DOT)arroworindicatorinscribedonthebaseplate.Tocheckonesprogressalongacourseorazimuth,ortoensurethattheobjectinviewisindeedthedestination,anewcompassreadingmaybetakentothetargetifvisible(here,thelargemountain).AfterpointingtheDOTarrowonthebaseplateatthetarget,thecompassisorientedsothattheneedleissuperimposedovertheorientingarrowinthecapsule.Theresultingbearingindicatedisthemagneticbearingtothetarget.Again,ifoneisusingtrueormapbearings,andthecompassdoesnothavepreset,pre-adjusteddeclination,onemustadditionallyaddorsubtractmagneticdeclinationtoconvertthemagneticbearingintoatruebearing.Theexactvalueofthemagneticdeclinationisplace-dependentandvariesovertime,thoughdeclinationisfrequentlygivenonthemapitselforobtainableon-linefromvarioussites.Ifthehikerhasbeenfollowingthecorrectpath,thecompasscorrected(true)indicatedbearingshouldcloselycorrespondtothetruebearingpreviouslyobtainedfromthemap.第8页Compassesaretobelaiddownonaleveledsurfacesotheneedlecouldpointtothemagneticnorthmoreaccurately,astothattheneedleonlyrestsorhangsonabearingfusedtothecompasscasing,ifusedatatilt,theneedlemighthitthecasingonthecompass,andhence,notmove.Thiswillgiveafaultyreading.Toseeiftheneedleiswellleveled,lookcloselyattheneedle,andtiltitslightlytoseeiftheneedleisswayingsidetosidefreelyandtheneedlenotcontactingthecasingofthecompass.Iftheneedletiltstoonedirection,tiltthecompassslightlyandgentlytotheopposingdirectionuntilthecompassneedleishorizontal,lengthwise.Itemstoavoidaroundcompassesaremagnetsofanykindandanyelectronics.Magneticfieldsfromelectronicscaneasilydisrupttheneedle,avoidingitfrompointingwiththeearthsmagneticfields,causinginterference.Theearthsnaturalmagneticforcesareconsiderablyweak,measuringat0.5Gaussandmagneticfieldsfromhouseholdelectronicscaneasilyexceedit,overpoweringthecompassneedle.Exposuretostrongmagnets,ormagneticinterferencecansometimescausethemagneticpolesofthecompassneedletodifferorevenreverse.Avoidironrichdepositswhenusingacompass,forexample,certainrockswhichcontainmagneticminerals,likeMagnetite.Thisisoftenindicatedbyarockwithasurfacewhichisdarkandhasametallicluster,notallmagneticmineralbearingrockshavethisindication.Toseeifarockoranareaiscausinginterferenceonacompass,getoutofthearea,andseeiftheneedleonthecompassmoves.Ifitdoes,itmeansthattheareaorrockthecompasswaspreviouslyat/oniscausinginterferenceandshouldbeavoided.第9页中文翻译稿用于侧向导航仪器：指南针1.罗盘的类型有两种广泛使用从根本上不同类型的罗盘。磁罗盘包含一个磁相互作用与地球磁场和对齐本身点磁极。简易圆规这种类型的显示方向的参考框架，在该方向的磁极是由于南方与北方。这些方向称为磁北极和磁南极。陀螺罗盘包含一个快速旋转的动态交互与地球自转，从而使指南针的指针旋转，直到它的旋转轴是平行地球的。因此指南针的轴指向地球旋转的两极，由于北部和南部的一个参照系。这些指示被分别称为真正的地理北极和地理南极。还有其他设备不属于传统所谓的罗盘，但也是基本方向确定的其他种类的设备。他们的工作“就像一个指南针”，或作为“指南针”，实际上还是是一个指南针。例如，全球定位系统（GPS）的卫星接收机在地面上确定自己的位置，作为真正的纬度和经度真实。如果正在移动接收，即使在走路的步伐，它可以按照其位置的变化，从而确定其运动方向的罗盘方位，并从那里相对其运动方向的东南西北方向。有些GPS接收机有两个天线，固定一段距离外，车辆的结构，通常飞机。确切的纬度和经度的天线可同时测定，使东南西北的方向来计算飞机的标题（在它的鼻子指向的方向），而不是它的运动方向，相对的，这将是不同的，如果有一个侧风。一个老得多的例子是指中国南方的战车，它像一个罗盘定向的航位推算工作。它是手工初始化，可能使用如天文观测北极星，以及此后每一个回合，保持指针瞄准所需的方向，通常以南部抵消。地球磁极与其旋转的轴并不一致，磁极的位置随时间而改变人的标准，并不是非常长的时间刻度。几年发生重大变动。（经过数百万年的真实极点方向也转向，因为大陆漂移。）对于在地球表面上任何一点的观察员，都存在一个角，这个角就是地理北极和磁场北极的夹角磁偏角。磁偏角在地球上的不同点是不同的，随着时间的变化。接近赤道，磁偏角是不超过几摄氏度，但它可以在北极和南极的纬度大得多。一些磁罗盘包括磁偏角补偿，使指南针显示真正的方向，相对于地球的旋转极的手段。这样一个指南针，用户必须知道当地的磁偏角值，并相应调整指南针第10页2.磁罗盘由磁化的指针（通常标记北端）地球的磁场，以配合本身的磁罗盘。指南针是任何磁性敏感的设备，能显示行星磁层的磁北的方向。面对的指南针一般突出的北部，南部，东部和西部的基点。通常情况下，作为一个独立的密封仪器磁化的酒吧或针后一个支点自由转动，或流体中移动，从而能够在偏北和偏南方向指向内置的罗盘。指南针，大大提高了旅游的安全性和效率，特别是海洋中遨游。指南针可以用来计算航向，六分仪用来计算纬度，并与海洋的天文计算经度。因此，它提供了一个很大的改进的导航能力，只是最近，如全球定位系统（GPS）等现代设备取代。指南针的发明在公元前2世纪和公元1世纪之间的中国汉族王朝。干指南针的发明1300年左右。在中世纪的欧洲，这是在20世纪初取代由充液磁指南针。其他更准确的设备已确定北部发明，不依赖于地球的磁场操作（已知的在正北这种情况下，作为反对以磁北）。罗经可以用来找到真正的北方，而不受杂散磁场，电力线路附近或有色金属附近群众。最近的发展是电子指南针，磁强计或光纤罗经没有可能犯错误的移动部分，它可以检测磁场方向。一个的磁力经常出现手持式GPS接收机内置可选子系统。磁罗盘，但仍然很受欢迎，尤其是在偏远地区，因为它们相对便宜，耐用，无需电源。磁罗盘是如何工作的作为“磁北”的指针罗盘磁针的心脏功能，因为与地球磁场线对齐。磁场对针的扭矩，拉一端或朝着地球的北磁极针杆，和其他对南磁极。更好的罗盘针安装在一个低摩擦的支点，因此它可以轻松地打开。针转当罗盘保持水平，直到几秒钟后对准北磁极。被定义为被吸引到地球的北磁极在加拿大北部，磁铁或罗盘针的“北”极。由于对立的两极吸引（“北”“南”）的北地球磁场极是实际上的地球磁场的南北极。罗盘针的北磁极是永远标记在某些方式：以鲜明的色彩，夜光涂料，或箭头。专业罗盘通常有条形磁铁粘到磁盘的底面中心旋转，因此它可以转动，被称为“罗盘卡”，它的基点和标度。更好罗盘“充液”;含针或磁盘的腔充满了液体，其目的是在潮湿的针振荡，所以它会安定下来，更迅速地指向北，也保护了针或磁盘休克。在导航地图上的方向表示与地域或正北方向的参考，对地理北极，地球的旋转轴的方向。由于地球磁极附近，但不作为其地理极点在同一地点，罗盘不指向正北。方向的罗盘点被称为磁北，位于加拿大东北部，北磁极的方向。根据指南针位于地球表面的正北和磁北之间的夹角称为磁偏角可以有很大的不同，增加的更远，一个是从地球的磁场本初子午线。当地的磁偏角是在大多数地图，使地图与指南针平行正北面向。磁极在加拿大东北和南极洲附近的地理区域，在地球磁场的变化，导致磁罗盘有这第11页样大的误差，他们是无用的，那么其他文书必须用于导航。3.磁罗盘是如何工作的作为“磁北”的指针罗盘磁针在其心脏功能，因为与地球磁场线对齐。磁场对针的扭矩，拉一端或朝着地球的北磁极针杆，和其他对南磁极。更好的罗盘针安装在一个低摩擦的支点，宝石轴承，因此它可以轻松地打开。针转当罗盘保持水平，直到几秒钟后对准北磁极。被定义为被吸引到地球的北磁极在加拿大北部，磁铁或罗盘针的“北”极。由于对立的两极吸引（“北”“南”）的北地球磁场极是实际上的地球磁场的南北极。罗盘针的北磁极是永远标记在某些方式：以鲜明的色彩，夜光涂料，或箭头。专业罗盘，而不是一针，通常有条形磁铁粘到磁盘的底面中心旋转，因此它可以转动，被称为“罗盘卡”，它的基