In1895,Germanfloodingmanufacturestheworld'sfirstDCelectricdrill.Theoutercasingismadeofcastirontodrill4mmholesonthesteelplate.Thethree-phasepowerfrequency(50Hz)isthenappeared,butthemotorspeedcannotexceed3000R/min.In1914,asinglestrokeexchangmotordrivenelectrictool,themotorspeedreached10,000r/min.In1927,anintermediatefrequencypowertoolwith150~200Hzhasoccurred.
Ithastheadvantagesofhighspeedofsingle-phasestrokemotorspeed,andhasasimpleandreliableadvantageofthree-phaseworkermotorstructure,butislimitedbytheuseofintermediatecurrentcurrents.
很乐意为您提供环境科学专业的英文介绍，包括概述、主要领域、相关技能和延伸知识。
EnvironmentalScienceisamultidisciplinaryfieldthatfocusesonthestudyoftheinteractionsbetweenthebiophysicalenvironmentandhumansociety.Thisincludesaspectssuchasair,water,soil,andtheatmosphere,aswellastheimpactofhumanactivityontheseelements.
Themainareaswithinenvironmentalscienceincludebutarenotlimitedto:
1.Ecology:Ecologyisthestudyoftherelationshipsbetweenorganismsandtheirenvironment.Itfocusesontheinteractionsofpopulations,communities,andecosystems,andhowtheseinteractionsinfluencethedistributionandabundanceoflife.
2.EnvironmentalChemistry:Environmentalchemistryconcernsthestudyofthetransformationandfateofchemicalsintheenvironment,includingtheireffectsonlivingorganisms.
3.EnvironmentalGeology:Environmentalgeologylooksattheroleofgeologicalprocessesandphenomenainaffectingenvironmentalqualityandpublichealth.Thisincludestopicslikesoilerosion,landuse,andtheeffectsofnaturaldisasters.
4.AtmosphericScience:Atmosphericsciencestudiesthecomposition,properties,andbehavioroftheEarth'satmosphere,consideringhowtheyareinfluencedbybothnaturalandhumanactivities.
5.WaterResourceManagement:Thisareadealswiththemanagementandconservationofwaterresources,includinggroundwater,surfacewater,andwaterquality.Itconsidershowhumanactivitiesimpactwatersupplyandtheenvironment,anddevelopssustainablewatermanagementstrategies.
Skillsrelevanttoenvironmentalscienceincludebutarenotlimitedto:
1.Scientificwritingandcommunication:Environmentalscientistsneedstrongwritingandcommunicationskillstoproducereports,articles,andproposalsthateffectivelycommunicatecomplexenvironmentalconceptstoawideaudience.
2.Dataanalysis:Environmentalscientistsoftencollectandanalyzelargeamountsofdatatounderstandenvironmentalprocesses.Theyneedstatisticalskillstoanalyzethisdataanddrawmeaningfulconclusions.
3.Fieldwork:Environmentalscientistsoftenneedtoconductfieldworktocollectsamplesanddata.Theyneedskillsinfieldmethods,datacollection,andsamplingtechniques.
4.Computerskills:Environmentalscientistsusecomputersoftwarefordataanalysis,modeling,andvisualization.Theyneedstrongcomputerskills,particularlyinareaslikeGIS(GeographicInformationSystems)andstatisticalanalysissoftware.
Extendedknowledgeinenvironmentalsciencemightcoverbutisnotlimitedto:
1.Environmentalpolicy:Understandinghowpolicyisformedandhowitaffectsenvironmentalmanagementiscrucialforenvironmentalscientists.Thisincludesknowledgeofinternationalagreements,nationallaws,andregulationsrelatedtoenvironmentalprotection.
2.Ecosystemmanagement:Ecosystemmanagementlooksatthemanagementofnaturalresourcesandthemaintenanceofecosystemserviceswhileconsideringsocial,economic,andenvironmentalfactors.
3.Environmentaltoxicology:Environmentaltoxicologylooksattheeffectsofchemicals,pollutants,andothersubstancesonlivingorganisms,particularlyhumans.Itconsidersissueslikeexposure,riskassessment,andhealthimpacts.
4.Climatechange:Understandingclimatechangeanditsimpactontheenvironmentiscrucialinenvironmentalscience.Thisincludesknowledgeofclimatescience,climatemodeling,andadaptationstrategiesforachangingclimate.
5.Sustainability:Sustainabledevelopmentisakeyconceptinenvironmentalscience,consideringthebalancebetweeneconomic,social,andenvironmentalneedswhiledevelopingsolutionstoenvironmentalproblems.
IhopethisintroductiontoEnvironmentalScience
Now,wehavegreatpleasureintroducingyouourcompany.ourcompanyisfoundbeforeseveraldecadeandproductingallkindsofdigitalproducts.Havemadeamarketresearch,wefindthatthesethingsmakeourliveseasier.
Thedigitalproductslikethecomputerandthecellphonehavecompletelymadeagreatimpactonourlife.Theseproductshavebothledtomuchgreaterefficiencyinmanyaspectsofourdailylivesandproducedmanyeconomicbenefitsaswell.Thedigitalagehascontributedtomanylaborsavingtechnologiesatthesametimeasimprovingthequalitystandardsofproduction..
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fbi介绍法:
1、F就是介绍产品的特点，特征，性能，主要是对产品某一个方面的客观描述。
2、B是产品的利益，好处，就是你说产品好，要说出好在哪里，比别人的好，好在哪里？
3、I，就是通过描述产品的使用场景给顾客的冲击，作用，影响。
以上就是fbi介绍法的介绍，所有的产品和服务都可以用这三句话来介绍给顾客，把产品特征带来的好处，通过描绘一个使用场景，让顾客联想到自己使用产品时间问题被解决了，从而激发顾客的需求，进而购买。
impact的基本含义及用法介绍
1、作为名词时，意为影响;撞击;强大作用;冲撞;冲击力。
例句：ThereportassessestheimpactofAIDSonthegaycommunity.
这个报告评估了艾滋病对同性恋群体的影响。
TheimpactoftheblowknockedJackoffbalance.
这一记猛击把杰克打了个趔趄。
Theimpactjarredhisarm.
冲击力震伤了他的胳膊。
2、作为动词时，意为冲击;撞击;(对某事物)有影响。
例句：Herfather'sdeathimpactedgreatlyonherchildhoodyears.
父亲去世对她的童年造成巨大影响。
