【英文标准名称】:StandardPracticeforSamplingPhytoplanktonwithConicalTowNets
【原文标准名称】:用圆锥拖网取样可繁殖海洋浮游生物的标准实施规程
【标准号】:ASTMD4132-1982(2004)
【标准状态】:现行
【国别】:
【发布日期】:1982
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E47.01
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:资源取回;浮游生物;抽样方法;渔网;污染控制;水质
【英文主题词】:
【摘要】:Theadvantagesofconicaltownetsareasfollows:3.1.1Theyarerelativelyinexpensive,easytoconstruct,andhighlyversatileinavarietyofsurfacewaters.3.1.2Theycanbeusedfromasmallpoweredboatwithaminimumofauxiliaryequipment.3.1.3Theyprovideasimplemeansbywhichtocollectqualitativesamplesofmacro-andmicro-plankton.3.1.4Theycanbeadaptedwithaflowmetertocollectsemiquantitativesamplesofmacro-andmicro-plankton.Thedisadvantagesofconicaltownetsareasfollows:3.2.1Theyareeffectiveonlywheredrawnthroughastratumofwaterhavingconsiderablethickness.Theyarenotsuitableforcollectingsamplesfromasmallorrestrictedregion.3.2.2Theyarenotsuitableforcollectionsinveryshallowwater.3.2.3Theycollectonlyqualitativesamples,orsemiquantitativesampleswhenusedwithaflowmeter.3.2.4Cloggingofthenetbyextraneousmaterials,suchasfloatingvascularplantsordebriscancauseerroneousresults.3.2.5Ifdiscretedepthsaresampledusingahorizontaltow,thesamplecanbecontaminatedwithorganismsfromotherdepthsduringthedeploymentandretrievalofthesamples.Thereareseveralspecialconsiderationsthatshallbeobservedwhenusingconicaltownets.Theyareasfollows:3.3.1Theconicalnetsamplersaredesignedtobetowedatspeedslessthan3knots;however,greaterspeedshavebeenusedforthelargernetswithaconcomitantincreaseincapture.3.3.2Althoughthereisatendencytousethesmallestmeshsizeavailable,thereistheliabilityofsmallmeshsizesreducingthecollectionefficiencyandincreasingequipmentfailurethroughtearing.3.3.3Ifdiscretedepthsamplesarerequired,anopeningandclosingnetdeviceshouldbeinstalledonthesampler.3.3.4Thenetsshouldbewashedfrequentlyandinspectedforpin-sizeholes,tears,netdeterioration,andotheranomalies.3.3.5Followinguse,wetnetsshouldbesuspendedfulllengthinairandinsubduedlightandallowedtodry.1.1Thispracticecoverstheproceduresforobtainingqualitativesamplesofaphytoplanktoncommunitybyuseofconicaltownets.Netswillnotretainallphytoplanktontaxa;forexample,nannoplanktonandultraplanktongenerallywillpassthroughanet.1.1Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:Z16
【国际标准分类号】:
【页数】:2P.;A4
【正文语种】:


【英文标准名称】:IPMulticastforDigitalMPEGNetworks
【原文标准名称】:数字MPEG网络用IP多点传送
【标准号】:ANSI/SCTE42-2002
【标准状态】:作废
【国别】:美国
【发布日期】:2002-09-12
【实施或试行日期】:
【发布单位】:美国国家标准学会(ANSI)
【起草单位】:SCTE
【标准类型】:()
【标准水平】:()
【中文主题词】:
【英文主题词】:Communicationtechnology;Digital;IP;MPEG;Network;Telecommunications;Transmissiontechnique
【摘要】:ThestandarddescribestwomethodstotransmitIPdatagramsoverMPEG2digitaltransportstreams.ItdescribestheuseofDigitalVideoBroadcasting(DVB)Multi-ProtocolEncapsulation(MPE)DatagramSectionsandtheAdvancedTelevisionSystemsCommittee's(ATSC)AddressableSections,toencapsulateIPdatagramsforsubsequentsegmentationintofixedlengthMPEGtransportpackets.ItalsodescribeshowtheencapsulateddatawillbeincludedwithinanMPEGPrograminamannerthatallowsadigitalMPEGDecodertoefficientlylocatethedataPIDstreamscarryingmulticastIPcontent.
【中国标准分类号】:M11
【国际标准分类号】:35_180;33_040_20
【页数】:
【正文语种】:英语