北交大-交通安全

TRANSPORTATIONSAFETYChapter1IntroductionA.GeneralFacts

SomeData

-42,116lives(trafficrelatedfatalities)andmorethan3milliontrafficrelatedinjuriesin2001. -TransportationaccidentsaretheseventhsingleleadingcauseofdeathintheUnitedStates. -Motorvehiclecrashesaretheleadingcauseofdeathforpeopleforeveryagefrom4through33yearsold(basedon1998data). -Transportationcrashesremaintheleadingcauseofaccidentaldeath(Tables1and2).

-Motorvehiclecollisionsaccountformorethanabout90percentoftransportation-relateddeathsandanevenhigherpercentageoftransportationinjuries.

2. SomeIssues

-Thehighestpriorityisto“Promotepublichealthandsafetybyworkingtowardtheeliminationoftransportation-relateddeaths,injuriesandpropertydamage” -Safetyrateisusuallyusedforcrashanalysis.Safetyratesareestimatedbydividingthenumberofevents(crashes,fatalities,injuries,etc)bysomemeasureofexposureorsubgroup(population,numberoftrips,vehiclemilestraveled,registeredvehicles,driverlicensed,etc). -Reductioninfatalityratesmaybemainlyattributedtoimprovementsinthevehiclesystems,bettereducation,higherefficienciesoftheemergencymanagementsystems,increasedlawenforcement,andbettertransportationpolicies. -Specialconcerns–Transportationtoandfromschools,pedestrianandbicycle,specialpopulationgroups,transportationdataneeds,securityoftransportationsystemsagainstcrimeandterrorism,internationaltrendsinroadsafety,etc.B.SomeSafetyConcerns1. TransportationofSchoolChildren

-Schoolbussafetyhasreceivedthemostnotice,butotherissuessuchassafetyofschoolchildrentransportedbycars,bytransit,orwhilewalkingorbikingtoschoolarealsokeys. -LeadingmodesofschooltransportationaccordingtotheNationwidePersonalTransportationSurvey(NPTS)byDOT–1995(POV–50%,schoolbuses–32%,walking10%,biking–1%). -Numberoffatalcrashesandfatalitiesamongoccupantsaged5-19occurredduringschoolyear,betweenthehoursof6amto9amand2pmto5pm:Automobilesandotherprivatevehiclesaccountedformostoftheincidents. -Schoolbusesprovideoneofthesafestformsoftransportationaccordingtothestatistics.From1987to1997,outofatotalof420,000fataltrafficcrashes,1,298orjustover0.3%wereschoolbusrelated.Nevertheless,schoolbussafetydrawsgreaterattentionwheneveranincidenthappens.

-Mostofthechildreninvolvedinschoolbusrelatedcrasheswerekilledoutsidethebus.Mostofthechildrenwerestruckwhentheywereexitingorboarding. -Countermeasures:drivertraining,educatingchildrenaboutsafety,enforcement,etc. -FloridaStudybyCUTR.2. PedestrianandBicyclesSafety

-Pedestrianandbicyclefatalitieshavedeclinedmorerapidlythanmotoristfatalities. -NPTS:walkingtripsdeclinedfrom9.3%to5.5%between1977and1995,whilebicycletripsincreasedfrom0.6%to0.9%. -Usuallypedestriansandbicyclistsarecombinedtogetherasnon-motorizedtransportation,buttheyareverydifferentindemographics,sourcesofinjuries,physicsofoperation,waysoffollowingtrafficlaws,legalresponsibilities,etc.

-Pedestrianaccountedfor78,000(2.6%)of3.0millioninjuriesin2001but4882(11.6%)ofthe42,116highwayfatalities. -Concernsofrelativerisk–lackofexposuredata. -Children5-15yearsoldaccountedfor16%oftheUSpopulationin1997but20%ofpedestrianinjuriesand9%ofpedestrianfatalities. -Elderly65yearsandolderaccountedfor13%ofthepopulationbut8%ofinjuriesand22%offatalities. -29%ofpedestrianskilledincrashesin1997wereintoxicated(BAC>0.1ormore).Alcoholusebymotoristisalsoafactorforpedestrian-motorvehiclecollisions. -Visibility:two-thirdsofallpedestrianfatalitiesoccurredduringlowlightconditions,81%ofpedestrianfatalitiesof21to44yearsagegroupoccurredduringlowlightconditions. -Bicyclesafety:Fewerdeathsthanforpedestriansbutnearlyasmanyinjuries.In2001,728bicyclistswerekilledand45,000wereinjured.

-Although90%ofbicyclefatalitiesinvolveacollisionwithamotorvehicle,mostbicycleinjuriesdonotinvolveamotorvehicle.Mostcommontypesofbicycleinjuriesareduetofallsandcollisionwithfixedobjects. -Bicyclefatalitiesbyageofbicyclists(1875to1997) -Mostcrashesoccurredwhenbicyclistandmotoristwereonintersectingpathsorwhenonewasturning. -Countermeasureideasforimprovingbicyclesafetyare: (1)Wearingahelmetreducestheriskofheadandbraininjuryamongcyclistbyabout70% (2)Obeyingtrafficrules. (3)Usinglightsandreflectorsatnight. (4)Establishingmorebicyclelanesonornearurbanroads.3. SafetyofSpecialPopulationGroups

-Groups:olderdrivers,elderly,youngdrivers,schoolagechildren,peoplewithdisabilities,internationaltourists,pedestrians,bicyclists,newimmigrants,etc. -Addressinggeneralsafetyproblemsofeverybodyisnoteffectiveallthetime.Differentgroupshavedifferentneedsandhighwaysafetyproblems. -Anotherwayistoaddressthecriticalissuesandconcernsofspecialpopulationgroupsseparately.Usuallythosegroupsidentifiedashighrisk. -ResearchStudybyLuatUSF4. TransportationDataNeeds -Whilethereisagreatdealofinformationknownabouttransportationaccidentsandincidentsandtheresultingfatalities,injuries,andpropertydamage,thereismuchthatisunknown. -Outofthetwobroadcategoriesofsafetydata,i.e.,outcomedataandexposuredata,thesecondoneishardertocollectandnotaccuratelyavailableinmostofthecases. -Themajorexposuredataneedsinclude: (1)Becausethecommonexposuremeasureforhighwaymode(VMT-vehicle-miletraveled)isderivedfromasample,methodstoimprovethatanderrorbarsofVMTwouldbeveryusefulinterpretingfatalityandcrashrates. (2)Measuresofexposuresofspecificpopulations(e.g.Elderlydrivers,andchildren)andexposuretospecificconditions(e.g.adverseweather,lightconditions,etc)arenotavailableparticularlyforhighwaymode. (3)Exposuremeasuresforcommercialwaterborneandpipelinemodes (4)Abettermeasureofexposureforrecreationalboating,etc. -Majoroutcomedataneedlieswithdetailedinformationonpropertydamageonlycrashesinhighwaymode.5. InternationalTrendsinRoadSafety

-In1996,morethan671millionvehicleswereregisteredintheworld,upfrom411millionin1980. -UnitedStateshasthemostnumberofvehiclesbyfar(morethan200million)butitsshareoftheworldtotalhasdeclined. -Accuratedataonworldwidenumberoffatalitiesandinjuriesinvolvingmotorvehiclesareunknown.AccordingtoBritain’sTRRL,fatalitiesareestimatedtobe300,000andinjuriesaround10-15million.Someotherestimatesareevenhigher.E.G.,RedCrossputtrafficdeathsat500,000in1990. -Comparisonofmotorvehiclefatalitiesinaselectedsetofcountries6. TerrorismandTransportationSecurity

-MountingconcernoversecurityoftransportationfacilitiesandoperationbothintheUnitedStatesandoverseas.End第一節(jié)活塞式空壓機(jī)的工作原理第二節(jié)活塞式空壓機(jī)的結(jié)構(gòu)和自動(dòng)控制第三節(jié)活塞式空壓機(jī)的管理復(fù)習(xí)思考題單擊此處輸入你的副標(biāo)題，文字是您思想的提煉，為了最終演示發(fā)布的良好效果，請(qǐng)盡量言簡意賅的闡述觀點(diǎn)。第六章活塞式空氣壓縮機(jī)

piston-aircompressor壓縮空氣在船舶上的應(yīng)用：

1.主機(jī)的啟動(dòng)、換向；

2.輔機(jī)的啟動(dòng)；

3.為氣動(dòng)裝置提供氣源；

4.為氣動(dòng)工具提供氣源；

5.吹洗零部件和濾器。

排氣量:單位時(shí)間內(nèi)所排送的相當(dāng)?shù)谝患?jí)吸氣狀態(tài)的空氣體積。單位：m3/s、m3/min、m3/h第六章活塞式空氣壓縮機(jī)

piston-aircompressor空壓機(jī)分類：按排氣壓力分：低壓0.2～1.0MPa；中壓1～10MPa；高壓10～100MPa。按排氣量分：微型<1m3/min；小型1～10m3/min；中型10～100m3/min；大型>100m3/min。第六章活塞式空氣壓縮機(jī)

piston-aircompressor第一節(jié)活塞式空壓機(jī)的工作原理容積式壓縮機(jī)按結(jié)構(gòu)分為兩大類：往復(fù)式與旋轉(zhuǎn)式兩級(jí)活塞式壓縮機(jī)單級(jí)活塞壓縮機(jī)活塞式壓縮機(jī)膜片式壓縮機(jī)旋轉(zhuǎn)葉片式壓縮機(jī)最長的使用壽命-

----低轉(zhuǎn)速（1460RPM），動(dòng)件少（軸承與滑片），潤滑油在機(jī)件間形成保護(hù)膜，防止磨損及泄漏，使空壓機(jī)能夠安靜有效運(yùn)作；平時(shí)有按規(guī)定做例行保養(yǎng)的JAGUAR滑片式空壓機(jī)，至今使用十萬小時(shí)以上，依然完好如初，按十萬小時(shí)相當(dāng)于每日以十小時(shí)運(yùn)作計(jì)算，可長達(dá)33年之久。因此，將滑片式空壓機(jī)比喻為一部終身機(jī)器實(shí)不為過?；?葉)片式空壓機(jī)可以365天連續(xù)運(yùn)轉(zhuǎn)并保證60000小時(shí)以上安全運(yùn)轉(zhuǎn)的空氣壓縮機(jī)1.進(jìn)氣2.開始?jí)嚎s3.壓縮中4.排氣1.轉(zhuǎn)子及機(jī)殼間成為壓縮空間，當(dāng)轉(zhuǎn)子開始轉(zhuǎn)動(dòng)時(shí)，空氣由機(jī)體進(jìn)氣端進(jìn)入。2.轉(zhuǎn)子轉(zhuǎn)動(dòng)使被吸入的空氣轉(zhuǎn)至機(jī)殼與轉(zhuǎn)子間氣密范圍，同時(shí)停止進(jìn)氣。3.轉(zhuǎn)子不斷轉(zhuǎn)動(dòng)，氣密范圍變小，空氣被壓縮。4.被壓縮的空氣壓力升高達(dá)到額定的壓力后由排氣端排出進(jìn)入油氣分離器內(nèi)。4.被壓縮的空氣壓力升高達(dá)到額定的壓力后由排氣端排出進(jìn)入油氣分離器內(nèi)。1.進(jìn)氣2.開始?jí)嚎s3.壓縮中4.排氣1.凸凹轉(zhuǎn)子及機(jī)殼間成為壓縮空間，當(dāng)轉(zhuǎn)子開始轉(zhuǎn)動(dòng)時(shí)，空氣由機(jī)體進(jìn)氣端進(jìn)入。2.轉(zhuǎn)子轉(zhuǎn)動(dòng)使被吸入的空氣轉(zhuǎn)至機(jī)殼與轉(zhuǎn)子間氣密范圍，同時(shí)停止進(jìn)氣。3.轉(zhuǎn)子不斷轉(zhuǎn)動(dòng)，氣密范圍變小，空氣被壓縮。螺桿式氣體壓縮機(jī)是世界上最先進(jìn)、緊湊型、堅(jiān)實(shí)、運(yùn)行平穩(wěn)，噪音低，是值得信賴的氣體壓縮機(jī)。螺桿式壓縮機(jī)氣路系統(tǒng)：

A

進(jìn)氣過濾器

B

空氣進(jìn)氣閥

C

壓縮機(jī)主機(jī)

D

單向閥

E

空氣/油分離器

F

最小壓力閥

G

后冷卻器

H

帶自動(dòng)疏水器的水分離器油路系統(tǒng)：

J

油箱

K

恒溫旁通閥

L

油冷卻器

M

油過濾器

N

回油閥

O

斷油閥冷凍系統(tǒng)：

P

冷凍壓縮機(jī)

Q

冷凝器

R

熱交換器

S

旁通系統(tǒng)

T

空氣出口過濾器螺桿式壓縮機(jī)渦旋式壓縮機(jī)

渦旋式壓縮機(jī)是20世紀(jì)90年代末期開發(fā)并問世的高科技?jí)嚎s機(jī)，由于結(jié)構(gòu)簡單、零件少、效率高、可靠性好，尤其是其低噪聲、長壽命等諸方面大大優(yōu)于其它型式的壓縮機(jī)，已經(jīng)得到壓縮機(jī)行業(yè)的關(guān)注和公認(rèn)。被譽(yù)為“環(huán)保型壓縮機(jī)”。由于渦旋式壓縮機(jī)的獨(dú)特設(shè)計(jì)，使其成為當(dāng)今世界最節(jié)能壓縮機(jī)。渦旋式壓縮機(jī)主要運(yùn)動(dòng)件渦卷付，只有磨合沒有磨損，因而壽命更長，被譽(yù)為免維修壓縮機(jī)。

由于渦旋式壓縮機(jī)運(yùn)行平穩(wěn)、振動(dòng)小、工作環(huán)境安靜，又被譽(yù)為“超靜壓縮機(jī)”。

渦旋式壓縮機(jī)零部件少，只有四個(gè)運(yùn)動(dòng)部件,壓縮機(jī)工作腔由相運(yùn)動(dòng)渦卷付形成多個(gè)相互封閉的鐮形工作腔，當(dāng)動(dòng)渦卷作平動(dòng)運(yùn)動(dòng)時(shí)，使鐮形工作腔由大變小而達(dá)到壓縮和排出壓縮空氣的目的。活塞式空氣壓縮機(jī)的外形第一節(jié)活塞式空壓機(jī)的工作原理一、理論工作循環(huán)（單級(jí)壓縮）工作循環(huán)：4—1—2—34—1吸氣過程

1—2壓縮過程

2—3排氣過程第一節(jié)活塞式空壓機(jī)的工作原理一、理論工作循環(huán)（單級(jí)壓縮）

壓縮分類：絕熱壓縮：1—2耗功最大等溫壓縮：1—2''耗功最小多變壓縮：1—2'耗功居中功＝P×V（PV圖上的面積）加強(qiáng)對(duì)氣缸的冷卻，省功、對(duì)氣缸潤滑有益。二、實(shí)際工作循環(huán)（單級(jí)壓縮）1.不存在假設(shè)條件2.與理論循環(huán)不同的原因：1）余隙容積Vc的影響Vc不利的影響—?dú)埓娴臍怏w在活塞回行時(shí)，發(fā)生膨脹，使實(shí)際吸氣行程（容積）減小。Vc有利的好處—

（1）形成氣墊，利于活塞回行；（2）避免“液擊”（空氣結(jié)露）；（3）避免活塞、連桿熱膨脹，松動(dòng)發(fā)生相撞。第一節(jié)活塞式空壓機(jī)的工作原理表征Vc的參數(shù)—相對(duì)容積C、容積系數(shù)λv合適的C：低壓0.07-0.12

中壓0.09-0.14

高壓0.11-0.16

λv＝0.65—0.901）余隙容積Vc的影響C越大或壓力比越高，則λv越小。保證Vc正常的措施：余隙高度見表6-1壓鉛法—保證要求的氣缸墊厚度2.與理論循環(huán)不同的原因：二、實(shí)際工作循環(huán)（單級(jí)壓縮）第一節(jié)活塞式空壓機(jī)的工作原理2）進(jìn)排氣閥及流道阻力的影響吸氣過程壓力損失使排氣量減少程度，用壓力系數(shù)λp表示：保證措施：合適的氣閥升程及彈簧彈力、管路圓滑暢通、濾器干凈。λp

（0.90-0.98）2.與理論循環(huán)不同的原因：二、實(shí)際工作循環(huán)（單級(jí)壓縮）第一節(jié)活塞式空壓機(jī)的工作原理3）吸氣預(yù)熱的影響由于壓縮過程中機(jī)件吸熱，所以在吸氣過程中，機(jī)件放熱使吸入的氣體溫度升高，使吸氣的比容減小，造成吸氣量下降。預(yù)熱損失用溫度系數(shù)λt來衡量（0.90-0.95）。保證措施：加強(qiáng)對(duì)氣缸、氣缸蓋的冷卻，防止水垢和油污的形成。2.與理論循環(huán)不同的原因：二、實(shí)際工作循環(huán)（單級(jí)壓縮）第一節(jié)活塞式空壓機(jī)的工作原理4）漏泄的影響內(nèi)漏：排氣閥（回漏）；外漏：吸氣閥、活塞環(huán)、氣缸墊。漏泄損失用氣密系數(shù)λl來衡量（0.90-0.98）。保證措施：氣閥的嚴(yán)密閉合，氣缸與活塞、氣缸與缸蓋等部件的嚴(yán)密配合。5）氣體流動(dòng)慣性的影響當(dāng)吸氣管中的氣流慣性方向與活塞吸氣行程相反時(shí)，造成氣缸壓力較低，氣體比容增大，吸氣量下降。保證措施：合理的設(shè)計(jì)進(jìn)氣管長度，不得隨意增減進(jìn)氣管的長度，保證濾器的清潔。2.與理論循環(huán)不同的原因：二、實(shí)際工作循環(huán)（單級(jí)壓縮）第一節(jié)活塞式