简介:为给GPS软件接收机的跟踪环提供精确的初始条件,捕获后得到的载波频率应在几十Hz范围内,所以必须寻找一种既能精确测量载波多普勒频移,又能有较快运算速度的方法。针对这一特点,提出了一种载噪比较高时采用相位测量和较低时采用长相干处理的载波频率精确估计策略。利用Matlab仿真产生的卫星中频数据作为数据源对该策略进行验证,结果表明当输入信号的载噪比大于35.5dB·Hz的时候,相位测量算法得到的多普勒频率值的误差保持在约10Hz之内。对于微弱信号的捕获,如果将相干处理的时间从200ms扩展到600ms,捕获频率的误差从3Hz减小到0.5Hz。此外,与传统的FFT方法相比,该方法的加法和乘法运算量分别降低了96.2%和35%。测试结果体现了该算法的有效性和优越性。
简介:Anenvironmentallyfriendlyprecursor,adenosine,hasbeenusedasadualsourceofCandNtosynthesizenitrogen-dopedcarboncatalystwith/withoutFe.Ahydrothermalcarbonizationmethodhasbeenusedandwateristhecarbonizationmedia.Themorphologyofsampleswith/withoutFecomponenthasbeencomparedbyHRTEM,andtheresultshowsthatFecanpromotethegraphitizationofcarbon.Furtherelectro-chemicaltestshowsthattheoxygenreductionreaction(ORR)catalyticactivityofFe-containingsample(C–FeN)ismuchhigherthanthatoftheFe-freesample(C–N).Additionally,theintermediatesofC–FeNformedduringeachsyntheticprocedurehavebeenthoroughlycharacterizedbymultiplemethods,andthefunctionofeachprocedurehasbeendiscussed.TheC–FeNsampleexhibitshighelectro-catalyticstabilityandsuperiorelectro-catalyticactivitytowardORRinalkalinemedia,withitshalf-wavepotential20mVlowerthanthatofcommercialPt/C(40wt%).Itisfurtherincorporatedintoalkalinepolymerelectrolytefuelcell(APEFC)asthecathodematerialandledtoapowerdensityof100mW/cm~2.
简介:TheeffectofTi(C,N)onpropertiesoflow-carbonMgO-Cbrickswasinvestigated.Thephasecompositionandthemicrostructureofthematrixoflow-carbonMgO-CbrickcontainingTi(C,N)werestudiedbyXRDandSEManalysistogetherwithEDS.TheresultsshowedthatTi(C,N)distributedinthematrixoflow-carbonMgO-Cbrickuniformlyafterbeingtreatedat1600℃for3hincokepowderbed,andTi(C,N)andMgOformedasolidsolution.Afterthetreatmentat1600℃for3hincokepowderbed,thebulkdensityandcoldcrushingstrengthoflow-carbonMgO-CbrickwithTi(C,N)decreased,andtheapparentporosityandlinearchangerateofspecimensincreased.Theoxidationresistanceoflow-carbonMgO-CbrickwithTi(C,N)wassuperiortothatoflow-carbonMgO-Cbrickwithnoadditives,butinferiortothatoflow-carbonMgO-CbrickwithAlpowder.TheslagresistanceofthespecimenwithTi(C,N)wasexcellentaswell.
简介:摘要 本工程位于山东沿海地区,沿路横跨小清河等河流,水下桩的侵蚀性很强,本试验室的所需攻克的技术难关就是设计选定合适的高性能混凝土施工配合比。
简介:ThepaperdefinesanextendedCesàrooperatorTgwithholomorphicsymbolgintheunitballBofCnasWhereg(z)=∑j=1∑nzjg/zjistheradialderivativeofg.Inthispaper,theauthorcharacterizesgforwhichTgisbounded(orcompact)ontheBlochspaceBandthelittleBlochspaceB0.
简介:QUALITATIVESTUDYOFSIALOMUCINSCHANGESDURINGN-METHYL-N-NITROSOUREA-INDUCEDCOLONICCARCINOGENESISINMICEWangQiang王强;WangYuanhe王元和;...