简介：Inthispaperamodeloftransvcrsalfilterispresentedtostudytheadaptivematchofthetimevariantchannel.Theleastmeansquareerrorfil-teringmethodisusedtoobtaintheweightingcoeffcientsofthefilter.Withthepurposeofspeedinguptheconvergenceoftheiterationequationofadaptivefiltering,anadaptivefactoroftheiterationstepsizeμ_aisderivedinthispaper.Theresultofcomputersimulationshowsthatinthecaseofusingadaptiveμ_a,theconvergencespeedoftheiterationequationisincreased2timesapproximatelyincomparisonwithconstantμ_f.Thestudysuggeststhattheadaptivefilterwithadaptiveμ_a.havetheperformancetofollowthechangeoftime-variantcharacteristicsofthechannel.

简介：MechanicalqualityfactorQmisakeycharacteristicparameterofHigh-overtonebulkacousticresonator(HBAR).Theeffectsofstructureparameter(thickness)andperfor?manceparameters(characteristicimpedanceandmechanicalattenuationfactor)ofsubstrate,piezoelectricfilmandelectrodeconstitutingHBARonQmarecarriedout.TherelationshipsbetweenQmandtheseparametersareobtainedbyalumpedparameterequivalentcircuitinsteadofdistributedparameterequivalentcircuitneartheresonancefrequency,andthean?alyticalexpressionsoiQmaregiven.TheresultsshowthatQmincreasesnon-monotonicallywiththecontinuousincreaseofthesubstratethicknessforHBARwithcertainpiezoelectricfilmthickness,anditapproachestothesubstratematerialmechanicalqualityfactorasthesubstratethicknessislarge.QmdecreaseswavilywiththecontinuousincreaseofthepiezoelectricfilmthicknessforHBARwithcertainsubstratethickness.SapphireandYAGwithlowmechanicallossareappropriateasthesubstratetogetalargerQm-TheelectrodelossmustbeconsideredsinceitcanreduceQm-ComparedwithAuelectrode,A1electrodewithlowerlosscanobtainhigherQmwhentheappropriateelectrodethicknessisselected.Inaddition,Qmdecreaseswiththeincreaseoffrequency.TheseresultsprovidethetheoreticalbasisforoptimizingtheparametersofHBARandshowthattrade-oflFsbetweenQmandmustbeconsideredinthedesignbecausetheirchangesareofteninconsistent.

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简介：在医药超声成像地里，由织物的速度不同类导致了以便获得高分辨率并且改正阶段错误，联合最小的变化beamforming的一个高分辨率的医药超声成像方法和一般连贯因素被介绍。首先，从元素的数据为集中被推迟；然后，多信道的数据被用于最小的变化beamforming；同时，数据从数组空格被转变到横梁空格计算一般连贯因素；最后，一般连贯因素习惯于重量最小的变化beamforming的结果。医药图象被成像系统得到。实验基于点目标和无回声的包囊目标被用来验证建议方法。结果证明在分辨率，对比和坚韧性的方面的建议方法比最小的变化beamforming和常规beamforming好。

简介：为浅水里的单个模式的靠近环的刺激的一个最佳的算法被介绍。由分析草地函数矩阵的评价价值的协变性，一个最佳的来源数组重量矩阵被介绍估计草地工作矩阵。重量矩阵是一个单一的矩阵，并且矩阵元素的绝对值是相等的。基于重量，矩阵使刺激单个模式以最大的速度收敛并且稳定的算法。算法的优点被数字模拟证实。最后，浅水实验的结果被介绍，并且单个模式的精力比率比97%高。