简介：ThefirstAsia-PacificComparisonofAbsoluteGravimeters(APMP.M.G-K1)wasorganizedbytheNationalInstituteofMetrology(NIM)ofChinafromDecember21,2015toMarch25,2016inChangping,Beijing.Ourcompactcoldatomgravimeter(CCAG)wastransportedfromHangzhoutoBeijingwithalongdistanceofabout1200kmtoparticipateinthiscomparison.TheCCAGistheonlyone,tothebestofourknowledge,thatisbasedontheprincipleofatominterferometryamongalltheinstruments.Absolutegravityintheindicatedthreetestsiteshasbeenmeasuredasrequestedbytheorganizer.ThesensitivityofourCCAGisestimatedtobe90μGal∕Hzp,evenwhenthemeasurementsarecarriedoutwithoutanyvibrationisolation.Besides,theaccuracyofthisgravimeterhasbeenevaluatedtobeabout19μGalbyconsideringthesignificantsystemerrors.Ourresultsshowagoodagreementwiththegivenreferencevalue.

简介：Thisworkproposesamethodtoconcurrentlycalibratemultipleacousticspeedsindifferentmediumswithaphotoacoustic(PA)andultrasound(US)dual-modalityimagingsystem.First,physicalinfrastructureinformationofthetargetisacquiredthroughaUSimage.Then,werepeatedlybuildPAimagesaroundaspecialtargettoyieldthebestfocusedresultbydynamicallyupdatingtheacousticspeedsinadifferentmediumofthetarget.Withthesecorrectacousticpropagationvelocitiesintheaccordingmediums,wecaneffectivelyoptimizethePAimagequalityastheexperimentsproved,whichmightbenefitfutureresearchinbiomedicalimagingscience.