Calibration of the Distance Scale from Cepheids

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a rXiv:as tr o-ph/31291v115Jan23Calibration of the Distance Scale from Cepheids Pascal Fouqu´e 1,2,Jesper Storm 3,and Wolfgang Gieren 41Observatoire de Paris,LESIA,5,place Jules Janssen,F-92195Meudon Cedex,France 2European Southern Observatory,Casilla 19001,Santiago 19,Chile 3Astrophysikalisches Institut Potsdam,An der Sternwarte 16,D-14482Potsdam,Germany 4Astronomy Group,Departamento de F ´ısica,Facultad de Ciencias F ´ısicas y Matem´a ticas,Universidad de Concepci´o n,Casilla 160-C,Concepci´o n,Chile 1Introduction Since the discovery by Ms.Leavitt almost a hundred years ago that Cepheid vari-ables obey a tight relationship between their pulsation periods and absolute mag-nitudes,astronomers have made great eﬀorts to calibrate this relationship,and use it to estimate the distances to nearby galaxies in which Cepheids were found.For a very nice review of the early history of the Cepheid period-luminosity (PL)relation,see Fernie ([17]).With the course of time,the calibration of the PL re-lation was reﬁned,using new methods and improving data for both Cepheids in our own Galaxy and Cepheids which were found in increasing numbers in Local Group galaxies.In particular,the Magellanic Clouds have played a fundamen-tal role in our eﬀort to calibrate the PL relation (and still do so today,as we will show in this review),mainly because they are just near enough to make Cepheid apparent magnitudes bright enough for accurate photometry with even small telescopes,and on the other hand distant enough to have them,in a good approximation,all at the same distance.The slope of the PL relations can thus be determined directly from a sample of LMC Cepheids in contrast to a sampleof Galactic Cepheids where accurate individual distances,which are fundamen-tally diﬃcult to determine,are needed.In the course of the decades,it became clear that the Cepheid PL relation is a very powerful method to determine ex-tragalactic distances,and it was (and still is)generally considered as the most accurate and reliable stellar method to calibrate the extragalactic distance scale.For that reason,the HST Key Project on the Extragalactic Distance Scale chose the strategy to detect samples of Cepheids in a number of selected late-type galaxies and use them to measure the distances to these galaxies,which then served to calibrate other,more far-reaching methods of distance measurement to determine the Hubble constant in a region of constant Hubble ﬂow.It is clear that we have gone a very long way from the early attempts to calibrate the PL2Pascal Fouqu´e et al.relation,to the application of this technique to Cepheids in stellar systems as distant as20Mpc,as successfully done by the groups who have used the Hubble Space Telescope for this purpose.In spite of all these successes,it has also become clear over the past decade that there are still a number of problems with the calibration of the PL rela-tion which so far have prevented truly accurate distance determinations,to5 percent or better,as needed for the cosmological,and many other astrophysical applications.One basic problem has been the notorious diﬃculty to measure accurate,independent distances to Galactic Cepheids needed for a calibration of the PL relation in our own Galaxy(see next section).The alternative ap-proach,used many times,is to calibrate the PL relation in the LMC,but this requires an independent knowledge of the LMC distance whose determination has proven to be amazingly diﬃcult(see the review of A.R.Walker in this vol-ume).Another problem complicating the calibration of the PL relation is that Cepheids,as young stars,tend to lie in crowded and dusty regions in their host galaxies,making absorption corrections a critical issue.In more recent years, work on the PL relation has therefore increasingly shifted to the near-infrared where the problems with reddening are strongly reduced as compared to the optical spectral region.Another potential problem with the use of the Cepheid PL relation is its possible sensitivity to chemical abundances;if such a metal-licity dependence exists and is signiﬁcant,it has to be taken into account when comparing Cepheid populations in diﬀerent galaxies which have diﬀerent metal-licities.Therefore,while there has been a lot of progress on the calibration of Cepheids as distance indicators over the years,there is still room(and need)for a substantial improvement.It is the purpose of this review to contribute such progress,and our approach is to combine Galactic and LMC Cepheids in the best possible way to derive both an improved absolute calibration of the PL relation in a number of optical and near-infrared photometric bands and,in a parallel step,derive an improved distance to the Large Magellanic Cloud from its Cepheid variables.One of the reasons why a PL calibration from Galactic Cepheid variables is of advantage as compared to a calibration based on LMC Cepheids alone is the fact that in most large spiral galaxies,and in particular in those targeted by the HST Key Project,the mean metallicities are quite close to solar,implying that metallicity-related systematic eﬀects are minimized when comparing these extragalactic PL relations to the Galactic one,rather than to the one deﬁned by the more metal-poor population of LMC Cepheids.In aﬁnal step,we will test what our new Cepheid PL calibration implies for other stellar candles frequently used for distance work,such as RR Lyrae stars, red giant clump stars,and the tip of the red giant branch.2The Galactic vs.the LMC routes2.1The infrared surface brightness methodFifteen years ago,the classical method of calibrating the PL relation for Cepheids was to use the ZAMS-ﬁtting technique to determine the distances of a handfulCepheid Distance Scale3 of open clusters which happen to contain Cepheid members(Feast&Walker [16]).However,Hipparcos revealed that the distance of the calibrating cluster, the Pleiades,had to be revised substantially downwards,at a level where the distance diﬀerence between Hyades and Pleiades can no longer be explained only by metallicity diﬀerences.Therefore,some doubts were shed on the ZAMS-ﬁtting technique,and it became necessary toﬁnd alternative techniques of similar accu-racy.It is a measure of our progress to see that two such methods have emerged in the meantime.The main alternative method,based on the classical ideas of Baade and Wesselink,andﬁrst implemented by Barnes&Evans([2])consists in combining linear diameter measurements,as obtained from radial velocity curve integration, to angular diameter determinations coming from measurements of magnitudes and surface brightness to derive the mean diameter and distance of a Cepheid. The surface brightness estimates come from a relation between this parameter and a suitably chosen colour.In a comparison of the results of both methods,Gieren&Fouqu´e([23]) established that the Barnes-Evans zero point of the PL relation in the V band was0.15mag brighter than the ZAMS-ﬁtting zero point.However,the Barnes-Evans method uses the V−R colour index to estimate the surface brightness, and it was soon discovered that a much better estimate could come from infrared colours(Welch[61];Laney&Stobie[38]).Encouraged by the very promising near-infrared results,Fouqu´e&Gieren ([20])calibrated the infrared surface brightness technique,using both J−K and V−K colours,by assuming that non-variable,stable giants and supergiants follow the same surface brightness vs.colour relation as the pulsating Cepheids. Using23stars with measured angular diameters,mostly from Michelson in-terferometry,they checked that the slope of the relation directly derived from Cepheids was consistent,within very small uncertainties,with the slope derived from stable stars.This provided conﬁdence to also adopt the zero point from the giants and supergiants.They recalibrated the Barnes-Evans relation and showed that the accuracy of the infrared method for deriving the distances and radii of individual Cepheids was5to10times better than the results produced by an application of the optical counterpart of the technique.As in the optical surface brightness technique,a very important feature and advantage of the infrared surface brightness method is its very low,and almost negligible dependence on absorption corrections.At that time,only one Cepheid(ζGem)angular diameter had been mea-sured,with the lunar occultation technique(Ridgway et al.[50])and the agree-ment with our predicted angular diameter led some support to our choice of the zero point.However,that comparison suﬀered from the relatively large error of the Cepheid angular diameter measurement.More recently,Nordgren et al.([44])have conﬁrmed our calibrating surface brightness-colour relations from an enlarged sample of57giants with accurate interferometric measurements of their angular diameters.Interestingly,theyﬁnd a similar scatter to ours in these relations,which probably means that intrinsic4Pascal Fouqu´e et al.dispersion has been reached.Then,they used59direct interferometric diame-ter measurements for3Cepheids to compute their surface brightnesses,at the corresponding pulsation phases.From these measurements,they derived surface brightness-colour relations for theﬁrst time directly from the Cepheids them-selves,and conﬁrmed that the Cepheid surface brightnesses do indeed follow the calibrating relations obtained from stable giants and supergiants in the same colour range as Cepheids,yielding a zero point fully compatible with our pre-vious value from stable stars(3.941±0.004vs.3.947±0.003,respectively). Subsequently,Lane et al.([36])were able to go a step further and measure the angular diameter variations for2Cepheids,therefore allowing a measure of their distances and mean diameters independently of photometric measurements,but also conﬁrming the adopted calibrating relations.At the time of this review,three Cepheids have distance determinations based on interferometric measurements of their angular diameters.It is instructive to compare them to the distances derived from trigonometric parallaxes.This is done in Table1.In the case ofδCep,we have used the recent HST measurement by Benedict et al.([5]),which supersedes the less accurate Hipparcos measure-ment.ForζGem,the trigonometric parallax comes from Hipparcos,while forηAql we have used a weighted mean of Hipparcos and USNO measurements,as in Nordgren et al.([43]).The agreement is very good,especially in the case of the accurate trigonometric measurement ofδCep.Note that the small uncertainty associated with the interferometric distance determination ofδCep neglects the possible systematic uncertainties introduced by the use of the surface brightness vs.colour relations.Table parison of Cepheid distances from interferometry and trigonometric parallaxesδCep272±6273+12−11ηAql320±32382+150−84ζGem362±38358+147−81Cepheid Distance Scale5 not used in our previous studies,and also using fresh data from the literature whenever they had become available.The new Cepheid distance solutions from the infrared surface brightness technique are presented in Table7.Reddenings were adopted from Fernie’s database([18],column labelled FE1).In Fig.1,we show one such solution for the Cepheid X Cyg which is fairly representative for our whole,updated sample of Galactic Cepheid variables.Our new Galactic Cepheid distance data conﬁrm that the Galactic slopes of the PL relation are steeper than their LMC counterparts,in all photometric bands,as can be seen in Table2.The corresponding Galactic Cepheid PL relations are shown in Fig.2. Table2.Slopes of various PL relations in BV IW JHK bands(see explanations in the text)literature(N)revised(N)E(B-V)=0.10 However,there are systematic diﬀerences in the way the slopes given in Ta-ble2have been determined.For instance,the reddening corrections do not fol-low exactly the same law in Gieren et al.([25])and in the work of the OGLE team(hereafter OGLE2),and Groenewegen([30]).Even the deﬁnition of the reddening-free parameter W varies in the literature.In order to make things fully comparable,we have derived new LMC Cepheid PL relations in the optical (V IW)from the published OGLE2database,and in the infrared(JHK)from the sample kindly provided by M.Groenewegen,adopting the same reddening law as for our Galactic calibrators.For this,we have computed the values of the various coeﬃcients R v,R i,R w,R j,R h,R k for each calibrator according to the following formulae(from Laney&Stobie[37]and Caldwell&Coulson[10]):A vR v==1.82+0.205×(B−V)◦+0.0225×E(B−V)(2) E(B−V)6Pascal Fouqu´e et al.Fig.1.Illustration of the ISB method in the case of X Cyg:the points represent the photometrically determined angular diameters,and the line in panel(a)shows the bisectorﬁt to theﬁlled points.The curve in panel(b)delineates the angular diameter obtained from integrating the radial velocity curve at the derived distance.Red crosses in both panels represent points which were eliminated before theﬁt.This is necessary because near minimum radius the existence of shock waves in the Cepheid atmosphere, and possibly other eﬀects,do not allow a reliable calculation of the angular diameter from the photometry1R w==R v/4.02(4) E(B−V)A hR h==R v/11(6) E(B−V)R w deﬁnes the Wesenheit magnitude as:W=V−R w(V−I)(7) Then,we have computed the mean value of these coeﬃcients over our32 Galactic calibrators,assumed to be representative for the entire Galactic Cepheid population.As the rms dispersions turned out to be small(from0.003in K to 0.036in V),we decided to adopt the same constant values for all the Cepheids. These are:R v=3.30(8)Cepheid Distance Scale7Fig.2.Galactic PL relations in V IW JHK bands,determined from our new infrared surface brightness distance solutions for32Galactic Cepheid variables.Superimposed lines correspond to the LMC PL relations from OGLE2data,adoptingµ(LMC)=18.50 and a mean E(B−V)=0.10R i=1.99(9)R w=2.51(10)R j=0.82(11)8Pascal Fouqu´e et al.R h=0.48(12)R k=0.30(13) Another possible systematic eﬀect on PL slopes can arise from diﬀerences in the period ranges covered by the LMC and Galactic Cepheid samples.In log P,it ranges from0.1to1.5for the LMC(median0.59),versus0.6to1.6for the Milky Way(median1.16).However,cutting the LMC sample at0.6removes more than half of the OGLE2sample.We therefore adopted the cut at log P=0.4,as done by the OGLE2team.We also removed a few stars which were rejected in our linearﬁts toﬁnally adopt a common sample of644stars for V,I and W,and 447stars with2MASS random-phase magnitudes in J,H and K.The slopes of the corresponding PL relations derived from these samples are given in Table2 and the LMC PL relations are shown in Fig.3.Finally,we tested for the possibility that the diﬀerent PL slopes seen in the LMC and Galactic Cepheid samples could actually be an artifact of our method of distance determination.The most obvious source which could produce a signiﬁcant eﬀect on the PL slope of our Galactic sample is an error in the adopted value of the p-factor used to convert the Cepheid radial velocity into pulsational velocity.With a variation of the p-factor within any reasonable limits, however,it is clearly impossible to recover the slopes,in the diﬀerent bands, seen in the LMC Cepheid sample.We also tried to eliminate the most uncertain distances in our Galactic sample,which happen when there is an apparent phase shift between the angular and linear diameter variations in our solutions.Such phase shifts are seen in about one third of our Galactic Cepheids(always smaller than5percent)and are most likely due to a slight phase mismatch between the radial velocity curve and the photometric curves used in the analyses,which were not obtained simultaneously(see a detailed discussion of this in Gieren et al.([24])).Eliminating those potentially”problematic”stars did not change signiﬁcantly the derived Galactic slopes.Our adopted distances are based on a bisector linear least-squaresﬁt of the angular diameters vs.linear displacements at each phase.We also tested the eﬀect of adopting the inverseﬁt(all errors assumed to be carried by the angular diameters)instead of the bisectorﬁt,as recommmended in Gieren et al.([24]),without producing noticeable diﬀerences. As a result from these diﬀerent exercises carried out on the data,we conclude that our adopted distances are very robust against these kinds of subtleties.We therefore adopted two sets of zero points:theﬁrst one assumes our Galac-tic slopes and the second one assumes the revised LMC slopes.Results are given in Table3.It appears that the choice of slope only very slightly aﬀects the adopted zero points.This justiﬁes to force the more accurately determined LMC slopes to our 32Galactic calibrators,and allows a determination of the LMC distance in each band.The results are given in Table4.The values in Table4show that the distance moduli increase when the red-dening sensitivity of the band decreases.This is an annoying result,which we did not see in our1998paper(Gieren et al.[25]).The main diﬀerence is that we then used a reduced sample of about60LMC Cepheids(OGLE results wereCepheid Distance Scale9Fig.3.LMC PL relations in V IW JHK bands.Note that the relations in the J,H and K bands are derived from single-phase data,which introduces an additional dispersion to the relations not present in the optical V,I and W relations which are based on accurate mean magnitudes from the OGLE2databasenot available yet),among which about one half had individual reddening mea-surements,which yielded a mean value of E(B−V)=0.08,to be compared to the OGLE2mean value for Cepheids of0.147.10Pascal Fouqu´e et al.Table3.Absolute magnitudes of a10-day period Cepheid in V IW JHK bandsB−3.320±0.036V−4.049±0.034−4.087±0.039I−4.790±0.034−4.820±0.038W−5.919±0.032−5.952±0.035J−5.346±0.029−5.359±0.038H−5.666±0.031−5.672±0.040K−5.698±0.031−5.762±0.040Band LMC intercept at10daysµLMCWe therefore tested the eﬀect of replacing the individual OGLE2reddenings (which are constant within each of the84OGLE2sub-ﬁelds,but slightly varying fromﬁeld toﬁeld)by a mean value of E(B−V)=0.10,as done by the HST Key Project on the Extragalactic Distance Scale(HST-KP)team.Obviously the zero points of the corresponding PL relations are modiﬁed by this change,and when combined to the Galactic zero points derived by forcing the new LMC slopes given in last column of Table2to the Galactic data,we get the LMC distance moduli shown in Table5.It is clear that the agreement among the diﬀerent bands is now much better and,in fact,quite satisfactory.We note that the HST-KP for H◦determination is not fully consistent in that sense,because they use the OGLE2PL relations,but assume at the same time a mean LMC reddening of E(B−V)=0.10.If we use our new LMC PL relations with E(B−V)=0.10(last column of Table2)and assume a LMC distance modulus of18.50as they did,the resulting zero points are changed and appear in Table6.It is seen that this introduces a signiﬁcant diﬀerence in theCepheid Distance Scale11 Table5.LMC distance moduli in V IW JHK bands,derived by adopting a constant reddening of E(B−V)=0.10V14.453±0.02918.536±0.048I13.713±0.01818.530±0.041W12.597±0.00918.549±0.036J13.220±0.02618.577±0.045H12.873±0.02418.544±0.046K12.806±0.02618.567±0.04812Pascal Fouqu´e et al.to derive a PL relation zero point for Cepheids has been shown to be free of biases by subsequent studies(Pont[48],Lanoix et al.[39],Groenewegen&Oud-maijer[31]).The last of these studies is probably the most accurate one,and generalizes the result to diﬀerent photometric bands.We will adopt their zero points as the Hipparcos Galactic calibration,based on236Cepheids(median log P=0.82).For details about the method,the reader is referred to the above references.For a10-day period Cepheid,these zero points are given in Table6and compared to our zero points and to the adopted zero points of the HST-KP for H◦determination(Freedman et al.[22],Macri et al.[41],based on the original OGLE2LMC relations and on new infrared PL relations,assuming a LMC distance modulus of18.50).Please note that the values of the slopes and the deﬁnitions of W adopted to derive these zero points vary among these works. For comparison,the original Feast&Catchpole([15])V band zero point was −4.24±0.10.Table6also gives the HST-KP zero points derived adopting the new OGLE2LMC relations based on a mean reddening of E(B−V)=0.10. Table6.Zero point comparison for a10-day period Cepheid in V IW JHK bandsliterature E(B−V)=0.10We must be cautious with the conclusions to be drawn from Table6:there is an apparently good agreement between the Hipparcos and the original HST-KP zero points on one hand,and between the ISB Galactic and the revised HST-KP zero points on the other hand.How is this to be interpreted?First of all,if the Hipparcos and the original HST-KP zero points agree, why do they lead to diﬀerent distance moduli for the LMC?Simply because the adopted LMC PL relations have diﬀerent intercepts:Feast&Catchpole ([15])adopted a LMC PL relation in V from Caldwell&Laney([11])based on 88Cepheids with an intercept of14.42±0.02,and based on a mean adopted reddening of E(B−V)=0.08(30have individual BV I reddenings),while Freedman et al.([22])used the originally published OGLE2PL relations based on more than600Cepheids with an intercept of14.282±0.021and a mean reddening of0.147.The observed diﬀerence of0.14mag in intercepts is wellCepheid Distance Scale13 explained by the diﬀerence in adopted mean reddenings(0.067×3.3=0.22)and is suﬃcient to make the distance moduli discrepant.Please note that Feast& Catchpole([15])also added a metallicity correction of0.04mag,even increasing the discrepancy.In fact,the low accuracy of the Hipparcos zero points makes the observed diﬀerence between the Hipparcos and the ISB V zero points not signiﬁcant,as can be seen in Fig.4which displays,for the Cepheids with the highest weights, the value of the zero point estimate100.2ρvs.its uncertainty,together with the positions of the adopted Hipparcos and the ISB zero points.In the I band, the zero point diﬀerence is smaller,and clearly not signiﬁcant if we consider the alternative value published by Lanoix et al.([39]),which is−4.86±0.09.Finally, there is a good agreement in W-and K-band zero points,but this is probably quite fortuitous for the same reasons.Now,the excellent agreement between the revised HST-KP and the Galactic ISB Cepheid absolute magnitudes at a10-day period is clearly more signiﬁcant thanks to the high accuracy of both results.This basically demonstrates that the HST-KP adopted LMC distance modulus of18.50is very nearly correct.Fig.4.Hipparcos V PL relation individual zero points(expressed as100.2ρ,whereρis the zero point at log P=1)vs.their uncertainty;superimposed as vertical lines are the Hipparcos adopted mean(red)and the alternative ISB value(blue)2.3The ZAMS-ﬁtting calibrationFeast([14])published a revised list of31Galactic Cepheids belonging to open clusters or associations with distance moduli derived through the ZAMS-ﬁtting technique.He also explained why the values may not be modiﬁed by the Pleiades distance change after the Hipparcos measurement(simultaneous change of the14Pascal Fouqu´e et al.reference ZAMS of the same order of magnitude).In fact,his cluster distance values are very close to those published in Gieren&Fouqu´e([23]).Twenty-four of these cluster Cepheids lie in the same period range of our Galactic calibrators of the ISB technique.We have derived PL relations from these Cepheids,which are given below,and appear to be in good agreement with those derived from the ISB distances,although they are less accurate.They support the evidence that the Galactic PL slopes are somewhat steeper than the LMC ones.M v=−2.767±0.173(log P−1)−4.160±0.055(σ=0.271N=24)(14) M i=−3.273±0.164(log P−1)−4.837±0.051(σ=0.218N=18)(15) M w=−3.684±0.144(log P−1)−5.980±0.045(σ=0.191N=18)(16) M k=−3.766±0.170(log P−1)−5.694±0.051(σ=0.217N=18)(17)Very recently,Turner&Burke([56])published a revised list of46Cepheids belonging to clusters or associations.Fifteen of these Cepheids have ISB dis-tances in our current sample.The weighted mean of the distance moduli diﬀer-ences weﬁnd is not signiﬁcant and amounts to:µ(ISB)−µ(ZAMS) =+0.01±0.06σ=0.24(18) after rejection of AQ Pup(0.79±0.11diﬀerence-we note that cluster mem-bership of this star seems to be very uncertain).Other large diﬀerences are observed forδCep(0.37±0.11),BB Sgr(0.49±0.08),and U Car(−0.45±0.05). Excluding these stars,for which the case of membership in their respective clus-ters/associations is not strong(see original references cited in the paper of Turner &Burke),the rms dispersion is0.10,corresponding to3%distance precision for each set.From this comparison,we conclude that the Cepheid distance scale based on ZAMS-ﬁtting is consistent with the calibration from the ISB method.This may be a bit surprising given the many diﬃculties in the application of the ZAMS-ﬁtting method,and the doubts shed on the method after Hipparcos.3What may still be wrong in the LMC distance?3.1Reddening eﬀectsWe have seen previously how changing the adopted reddening may change our results.By reddening we mean both the reddening values and the reddening law. There is good evidence in the literature that the LMC reddening law may diﬀer from the Galactic one shortward of B(see,e.g.,Gochermann&Schmidt-Kaler [27]).However,this is of little concern for us.What is more important is that there is some evidence that the R v value may be lower in the LMC.For instance, Misselt et al.([42])ﬁnd R v values varying between2.16and3.31,and obtain a goodﬁt using the standard Cardelli et al.([12])reddening law for a mean valueCepheid Distance Scale15 of R v=2.4.Similar,but slightly higher values(between2.66and3.60)have been found in the SMC by Gordon&Clayton([28]).So,what we interpret as a smaller mean LMC reddening than the OGLE2values may in fact be due to a lower R v value.Concerning the reddening values,several studies have investigated both the foreground reddening due to our Galaxy(the LMC is at−33◦galactic latitude), and the internal reddening.They show that the reddening is patchy,with large variations from a line of sight to another.Concerning the foreground reddening,Schwering&Israel([53])ﬁnd from48’resolution maps a range of0.06to0.17in E(B−V),with an average value of 0.10.By comparison,the foreground reddening in front of the SMC is found more homogeneous,only varying from0.06to0.08.In the LMC,Oestreicher et al.([45])with a better resolution of10’alsoﬁnd a large range from0to0.15, with an average value of0.06±0.02.Concerning the internal reddening,Oestreicher&Schmidt-Kaler([46])ﬁnd a range of0.06to0.29,with a mean E(B−V)=0.16,while Harris et al.([32])ﬁnd a total average extinction of0.20,from which they conclude that the mean internal reddening amounts to E(B−V)=0.13mag.In comparison,Udalski et al.([58])use the mean magnitude of the Red Giant Clump(RGC)to derive the total reddening variations along the21LMC OGLE2ﬁelds(mainly along the bar).They divide eachﬁeld into4sub-ﬁelds and give a mean reddening along each of the84lines of sight,corresponding to a resolution of14.2’.The zero point of their reddening scale is given by three photometric measurements from the literature.Theyﬁnd a range of total extinction between 0.105and0.201,with a mean value over theﬁelds of0.137,and a mean Cepheid value of E(B−V)=0.147.However,Girardi&Salaris([26])have shown that the RGC mean absolute magnitude depends on population eﬀects(age and metallicity).This implies that the OGLE2method is only valid as long as it can be assumed that the population characteristics do not change along the LMC bar.In any case,Beaulieu et al.([4])have shown that the resolution of the OGLE2 maps is not suﬃcient to consider their reddenings as individual values for each Cepheid,since the PL residuals in V and I correlate along the reddening line in the case of LMC,as can be seen from Fig.5,reproduced from their paper.It is therefore tempting to use BV I OGLE2measurements to derive individ-ual reddenings,following the Dean et al.([13])precepts,adapted to the LMC metallicity as in Caldwell&Coulson([9]).Such measurements exist for329 Cepheids,which is about one half of the calibrating sample.Unfortunately,the result is disappointing,because when we apply the derived individual redden-ings to correct the mean V and I magnitudes,the dispersions of the PL relations increase.Finally,some authors use period-colour(PC)relations to estimate the red-denings.This is the case for instance in the various works based on Hipparcos parallaxes.However,it is well known that the PC relations have considerable intrinsic dispersion,but as shown by Feast&Catchpole([15]),these over-or。

数字指示秤术语与定义

数字指示秤术语与定义英文回答：A.Accuracy: The closeness of a measurement result to the true value of the measurand.Analog scale: A scale that displays the weight measurement using a pointer or needle that moves along a graduated scale.Auto-zero: A feature that automatically resets the scale to zero when there is no weight on the platform.Calibration: The process of adjusting a scale to ensure that it is measuring accurately.B.Capacity: The maximum weight that a scale can measure.Class: A classification system that indicates the accuracy and precision of a scale.Counting mode: A feature that allows the scale to count the number of items placed on the platform.Display: The part of the scale that shows the weight measurement.D.Decimal point: The point that separates the whole number part of a weight measurement from the fractional part.Digits: The number of digits that are displayed on the scale's display.Dual display: A scale that has two displays, one for the weight measurement and one for the unit of measurement.E.Error message: A message that is displayed on the scale's display when an error occurs.External calibration: A calibration procedure that requires the use of an external weight or calibration kit.External power supply: A power supply that is not built into the scale.F.Footprint: The area of the platform that is used to weigh objects.Function keys: Keys on the scale that are used to access different features or functions.G.Grams: The unit of measurement for weight in the metric system.Gross weight: The total weight of an object, including its packaging and any other materials.H.Hold function: A feature that allows the scale to hold the weight measurement on the display, even after the object is removed from the platform.I.Internal calibration: A calibration procedure that is performed using the scale's internal weight mechanism.Interval: The smallest increment that a scale can measure.IP rating: A rating that indicates the level of protection that a scale has against dust and water.J.Joules: The unit of measurement for energy.K.Kilograms: The unit of measurement for weight in the metric system.L.LCD display: A type of display that uses liquid crystals to create the numbers and characters.Load cell: A sensor that measures the weight of an object.M.Mechanical scale: A scale that uses a spring or balance to measure weight.Metric system: A system of measurement that uses meters, liters, and grams as the base units.Mode: A setting on the scale that determines how it will measure weight.N.Net weight: The weight of an object without its packaging or any other materials.Nonlinearity: A characteristic of a scale where the accuracy of the measurement decreases as the weight increases.O.OIML: The International Organization of Legal Metrology.P.Platform: The part of the scale that is used to hold the object that is being weighed.Precision: The ability of a scale to produce the same measurement result repeatedly.Q.Quality assurance: A set of procedures that are used to ensure that a scale is meeting its performance specifications.R.Resolution: The smallest change in weight that a scale can detect.S.Scale: A device that measures weight.Sensor: A device that converts a physical propertyinto an electrical signal.Serial port: A port on the scale that allows it to communicate with other devices.Sensitivity: The ability of a scale to detect small changes in weight.Stability indicator: An indicator on the scale'sdisplay that shows whether the weight measurement is stable.T.Tare function: A feature that allows the scale to subtract the weight of the container or packaging from the weight of the object.Tolerance: The amount of error that is allowed in a weight measurement.Transducer: A device that converts a physical propertyinto an electrical signal.U.Unit of measurement: The unit that is used to express the weight measurement.User manual: A document that provides instructions on how to use the scale.V.Verification: A process of checking the accuracy and precision of a scale.W.Weight: The force exerted on an object by gravity.X.X-ray scanner: A device that uses X-rays to create animage of the inside of an object.Y.Yield: The amount of product that is obtained from a given amount of raw material.Z.Zero: The point at which a scale's display reads zero when there is no weight on the platform.中文回答：A.准确度，测量结果与被测量真实值之间的接近程度。

生物等效性研究指导原则英文版

Technique Guideline for Human Bioavailability and BioequivalenceStudies on Chemical Drug ProductsContents(Ⅰ) Establishment and Validation for Biological Sample Analysis Methods (2)1. Common Analysis Methods (2)2. Method Validation (2)2.1 Specificity (2)2.2 Calibration Curve and Quantitative Scale (3)2.3 Lower Limit of Quantitation (LLOQ) (3)2.4 Precision and Accuracy (4)2.5 Sample Stability (4)2.6 Percent recovery of Extraction (4)2.7 Method Validation with microbiology and immunology (4)3. Methodology Quality Control (5)(Ⅱ) Design and Conduct of Studies (5)1. Cross-over Design (5)2. Selection of Subjects (6)2.1 Inclusion Criteria of Subjects: (6)2.2 Cases of Subjects (7)2.3 Division into Groups of the Subjects (7)3. Test and Reference Product, T and R (8)4. Sampling (8)(Ⅲ) Result Evaluation (9)(Ⅳ) Submission of the Contents of Clinical Study Reports (9)Technique Guideline for Human Bioavailability and BioequivalenceStudies on Chemical Drug ProductsSpecific Requirements for BA and BE Studies(Ⅰ) Establishment and Validation for Biological Sample Analysis MethodsBiological samples generally come from the whole blood, serum, plasma, urine or other tissues. These samples have the characteristics such as little quantity for sampling, low drug concentration, much interference from endogenous substances, and great discrepancies between individuals. Therefore, according to the structure, biological medium and prospective concentration scale of the analytes, it is necessary to establish the proper quantitative assay methods for biological samples and to validate such methods.1. Common Analysis MethodsCommonly used analysis methods at present are as follows: (1) Chromatography: Gas Chromatography(GS), High Performance Liquid Chromatography (HPLC), Chromatography－mass Spectrometry (LC-MS, LC-MS-MS, GC-MS, GC-MS-MS), and so on. All the methods above can be used in detecting most of drugs; (2) Immunology methods: radiate immune analysis, enzyme immune analysis, fluorescent immune analysis and so on, all these can detect protein and polypeptide; (3) Microbiological methods: used in detecting antibiotic drug.Feasible and sensitive methods should be selected for biologic sample analysis as far as possible.2. Method ValidationEstablishment of reliable and reproducible quantitative assay methods is one of the keys to bioequivalence study. In order to ensure the method reliable, it is necessary to validate the method entirely and the following aspects should be generally inspected:2.1 SpecificityIt is the ability that the analysis method has to detect the analytes exactly and exclusively, when interference ingredient exists in the sample. Evidences should be provided that the analytes are the primary forms or specific active metabolites of the test drugs. Endogenous instances, the relevant metabolites and degradation products in biologic samples should not interfere with the detection of samples. If there are several analytes, each should be ensured not to be interfered, and the optimal detecting conditions of the analysis method should be maintained. As for chromatography, at least 6 samples from different subjects, which include chromatogram of blank biological samples, chromatogram of blank biologic samples added control substance (concentration labeled) and chromatogram of biologic samples after the administration should beexamined to reflect the specificity of the analytical procedure. As for mass spectra (LC-MS andLC-MS-MS) based on soft ionization, the medium effect such as ion suppression should be considered during analytic process.2.2 Calibration Curve and Quantitative ScaleCalibration curve reflects the relationship between the analyte concentration and the equipment response value and it is usually evaluated by the regression equation obtained from regression analysis (such as the weighted least squares method). The linear equation and correlation coefficient of the calibration curve should be provided to illustrate the degree of their linear correlation. The concentration scale of calibration curves is the quantitative scale. The examined results of concentration in the quantitative scale should reach the required precision and accuracy in the experiment.Dispensing calibration samples should use the same biological medium as that for analyte, and the respective calibration curve should be prepared for different biological samples. The number of calibration concentration points for establishing calibration curve lies on the possible concentration scale of the analyte and on the properties of relationship of analyte/response value. At least 6 concentration points should be used to establish calibration curve, more concentration points are needed as for non-linear correlation. The quantitative scale should cover the whole concentration scale of biological samples and should not use extrapolation out of the quantitative scale to calculate concentrations of the analyte. Calibration curve establishment should be accompanied with blank biologic samples. But this point is only for evaluating interference and not used for calculating. When the warp* between the measured value and the labeled value of each concentration point on the calibration curve is within the acceptable scale, the curve is determined to be eligible. The acceptable scale is usually prescribed that the warp of minimum concentration point is within ±20% while others within ±15%. Only the eligible calibration curve can be carried out for the quantitative calculation of clinical samples. When linear scale is somewhat broad, the weighted method is recommended to calculate the calibration curve in order to obtain a more exact value for low concentration points. ( *: warp=[(measured value － labeled value)/labeled value]×100%)2.3 Lower Limit of Quantitation (LLOQ)Lower limit of quntitation is the lowest concentration point on the calibration curve, indicating the lowest drug concentration in the tested sample, which meets the requirements of accuracy and precision. LLOQ should be able to detect drug concentrations of samples in 3~5 eliminationhalf-life or detect the drug concentration which is 1/10~/20 of the C max. The accuracy of the detection should be within 80~120% of the real concentration and its RSD should be less than 20%. The conclusions should be validated by the results from at least 5 standard samples.2.4 Precision and AccuracyPrecision is, under the specific analysis conditions, the dispersive degree of a series of the detection data from the samples with the same concentration and in the same medium. Usually, the RSD from inter- or intra- batches of the quality control samples is applied to examine the precision of the method. Generally speaking, the RSD should be less than 15% and that around LLOQ should be less than 20%. Accuracy is the contiguous degree between the tested and the real concentrations of the biological samples (namely, the warp between the tested and the real concentrations of the quality-controlled samples). The accuracy can be obtained by repeatedly detecting the analysis samples of known concentration which should be within 85~115% and which around LLOQ should be within 80~120%.Generally, 3 quality-control samples with high, middle and low concentrations are selected for validating the precision and accuracy of the method. The low concentration is chosen within three times of LLOQ, the high one is close to the upper limit of the calibration curve, and the middle concentration is within the low and the high ones. When the precision of the intra-batches is detected, each concentration should be prepared and detected at least 5 samples. In order to obtain the precision of inter-batches, at least 3 qualified analytical batches, 45 samples should be consecutively prepared and detected in different days.2.5 Sample StabilityAccording to specific instances, as for biological samples containing drugs, their stabilities should be examined under different conditions such as the room temperature, freezing, thaw and at different preservation time, in order to ensure the suitable store conditions and preservation times. Another thing that should be paid attention to is that the stabilities of the stock solution and the analyte in the solution after being treated with, should also be examined to ensure the accuracy and reproducibility of the test results.2.6 Percent recovery of ExtractionThe recovery of extraction is the ratio between the responsive value of the analytes recovered from the biological samples and that of the standard, which has the same meaning as the ratio of the analytes extracted from the biologic samples to be analyzed. The recovery of extraction of the 3 concentrations at high, middle and low should be examined and their results should be precise and reproduceable.2.7 Method Validation with microbiology and immunologyThe analysis method validation above mainly aims at chromatography, with many parameters and principles also applicable for microbiological and immunological analysis. However, some special aspects should be considered in the method validation. The calibration curve of the microbiological and immunological analysis is non-linear essentially, so more concentration pointsshould be used to construct the calibration curve than the chemical analysis. The accuracy of the results is the key factor and if repetitive detection can improve the accuracy, the same procedures should be taken in the method validation and the unknown sample detection.3. Methodology Quality ControlThe unknown samples are detected only after the method validation for analysis of biological samples has been completed. The quality control should be carried out during the concentration detection of the biological samples in order to ensure the reliability of the method in the practical application. It is recommended to assess the method by preparing quality-control samples of different concentrations by isolated individuals.Each unknown sample is usually detected for only one time and redetected if necessary. In the bioequivalence experiments, biological samples from the same individual had better to be detected in the same batch. The new calibration curve should be established when detecting biological samples of each analysis batch and high, middle and low concentrations of the quality-control samples should be detected at the same time. Each concentration should at least have two samples and should be equally distributed in the detection sequence of the unknown samples. When there are a large number of unknown samples in one analysis batch, the number of the quality-control samples at different concentrations should be increased to make the quality-control samples exceed 5% of the unknown sample population. The warp of detection result from the quality-control samples should usually be less than 15%, while the warp of the low concentration point should be less than 20% and at most 1/3 results of the quality-control samples at different concentrations are allowed to exceed the limit. If the detection results of the quality-control samples do not accord with the above requirements, the detection results of the samples in this analysis batch should be blanked out.The samples with concentrations higher than the upper quantitation limit should be detected once more using corresponding diluted blank medium. As for those samples with concentrations lower than the lower quantitation limit, during pharmacokinetics analysis, those sampled before reaching C max should be calculated as zero while those after C max should be calculated as ND (Not detectable), so as to decrease the effect of the zero value on the AUG calculation.(Ⅱ) Design and Conduct of Studies1. Cross-over DesignCurrently, the crossover design is the most wildly applied method in the BE study. As for the drug absorption and clearance, there is a transparent variation among individuals. Therefore, the coefficient of variability among individuals is far greater than that of the individual himself. That is why the bioequivalence study is generally required to be designed on the principle of self crossover control. Subjects are randomly divided into several groups and treated in sequence, of whichsubjects in one group take the test products first and then the reference product, while subjects in the other take the reference products first and then the test products. A long enough interval is essential between the two sequences, which is called Wash-out period. In this way, every subject has been treated twice or more times sequentially, which is equal to self-control. Therefore, the influence of drug products on drug absorption can be discriminated from the others, and the effect of various test periods and individual difference on the results can be eliminated.Two-sequence crossover design, three-sequence crossover design are adopted respectively according to the amount of the test product. If two varieties of drug products are to be compared, the two-treatment, two-period or two-sequence crossover design will be a preferable choice. When three varieties of products (two test products and one reference product) are included, thethree-formulation, three-period and double 3×3 Latin square design will be the suitable choice. And a long enough wash-out period is required among respective periods.Wash-out period is set on purpose to eliminate the mutual disturbance of the two varieties of drug products and avoid the treatment in the prior period from affecting that of the next period. And the wash-out period is generally longer than or equal to 7 elimination half lives.While the half-lives of some drugs or their active metabolites are too long, it is not suitable to apply the crossover design. Under this circumstance, parallel design is adopted, but the sample size should be enlarged.However, as for some highly variable drugs, except for increase of the subjects, repetitive cross-over design can be applied, to test possibly existing difference in individual when receive the same preparation twice.2. Selection of Subjects2.1 Inclusion Criteria of Subjects:The difference among individuals of the subjects should be minimized so that the difference of the drug products can be detected. The inclusion criteria and exclusion criteria should be noted in the trial scheme.Male healthy subjects are recruited generally. And as to the drugs of special purpose, proper subjects are recruited according to specific conditions. If female healthy subjects are recruited, the possibility of gestation should be avoided. If the drugs to be tested have some known adverse effects, which may do harm to the subjects, patients can also be included as the subjects.Age: 18~ 40 years old generally. The difference in age of the subjects in one batch should not be more than 10 years.Body weight: not less than 50kg as to normal subjects. Body Mass Index (BMI), which is equal to body weight (kg)/ body height 2 (m2), is generally required to be in the range of standard body weight. For the subjects in one batch, the taken dosage is the same, the range of the bodyweight, therefore, should not have great disparity.The subjects should receive the overall physical examination and be proved healthy. There is not medical history of heart, kidney, digestive tract, nervous system, mental anomaly, metabolism dysfunction, and so on. The physical examination has revealed normal blood pressure, heart rate, electrocardiogram, and respiratory rate. Laboratory data have revealed normal hepatic function, renal function and blood function. Those examinations are essential to prevent the metabolism of drugs in vivo from being interfered by the diseases. According to the classification and safety of drugs, special items examinations are required before, during and after the test, such as the blood glucose examination, which is required in the drug trial of hypoglyceimic agents.In order to avoid the interference by other drugs, no administration of other drugs is allowed from two weeks before and till the end of the test. Moreover, the cigarette, wine,beverage with caffeine, or some fruit juice that may affect the metabolism of the drug, is forbidden during the trial period also. The subjects had better have no appetite of cigarette and wine. Possible effects of the cigarette-addicted history should not be neglected in the discussion of results.Due to the metabolism variance resulted by known genetic polymorphism of drugs, the safety factor which may be effected by the slow metabolism speed of drugs should be considered.2.2 Cases of SubjectsThe cases of the subjects should meet the statistic requirement. And according to the current statistical methods, 18~24 cases are enough for most drugs to meet the requirement of sample size. But as to some drugs of high variability, more cases may be required correspondingly.The cases of a clinic trial are determined by three fundamental factors: （1）Significance level: namely, the value of α, for which value 0.05 or 5% is often adopted;（2）Power of a test: namely, the value of 1-β. β is the index that represents the probability of the type error, which is also theⅡprobability of misjudging the actually efficacy drugs as inefficient drugs, and value not less than 80% is commonly stated; （3）Coefficient of variance（CV%）and Difference（θ）: In the equivalence test of two drugs, the greater CV% and θ of the test indexes are, the more cases are required. The CV% and θ are unknown before the trial and can only be estimated by the above parameters of the owned reference products or running the preliminary test. Moreover, when a BA test has been finished, the value of N can be calculated according to the parameters such as θ, CV% and 1-β and then compared with the cases adopted in the finished BA test to determine whether the cases are reasonable or not.2.3 Division into Groups of the SubjectsThe subjects should be randomly divided into different comparable groups. The cases of the two groups should guarantee the best comparability.3. Test and Reference Product, T and RThe quality of the reference products directly affect the results reliability of BE trial. Generally, the domestic innovator products of the same dosage form which has been approval to be on sale are commonly selected. If it failed in acquiring the innovator products, the key product on the market can also be chosen as the reference product and the related quality certifications (such as the test results of the assay and dissolution) and the reasons for option should be provided. When it comes to the drug study of specific purpose, other on-sale dosage forms which are of the same kind and similar with pharmaceutics properties are selected as the reference products and those reference products should be already on sale and qualified in quality. The difference in assay between the test product and reference product should not exceed 5%.The test product should be the scale-up product or manufacture scale product, which is consistent with the quality standards for clinical application. And the indexes such as the in vitro dissolution, stability, content or valence assay, consistency reports between batches should be provided to the test unit for reference. As for some drugs, the data of polymorphs and optical isomers should be offered additionally. The test and reference product should be noted with the advanced development unit, batch number, specification, storage conditions and expiry date.For future reference, the test and reference product should be kept long enough after the trialtill the product is approved to be on sale.4. SamplingThere is a significant sense in designing the sampling point to guarantee both the reliability of the trial results and the rationality of calculating the pharmacokinetics parameters. Commonly, there should be preliminary tests or the pharmacokinetics literatures at home and abroad served as the evidences of designing the reasonable sampling points. When the blood-drug concentration assay is performed, the absorption phase, balance phase and clearance phase should be considered overall. There must be enough sampling points in every phase of the C-T curve and around the T max. The concentration curve, therefore, can fully reflect the entire procedure of the drugs distribution in vivo. And the blank blood samples are taken before the administration. Then at least 2~3 points are sampled in the absorption phase, at least 3points are sampled near the C max and 3-5 points in the clearance phase. Try to avoid that the first point gets the C max, and running the preliminary test may avoid this. When the continuously-sampling results show that the drugs’ primary forms or the active metabolites are at the point of 3～5 half- lives or the blood drug concentration is 1/10～1/20 ofC max, the values of AUC0-t/AUC0-∞are generally bigger than 80% .For the terminal clearance item doesn’t affect the evaluation of the products’ absorption process much, as to the long half-life drugs, the sampling periods should be continued long enough, so that the whole absorption process can be compared and analyzed. In the multiple administration study, the BA of some drugs is known to beaffected by the circadian rhythm, samples of which should be taken 24 hours continuously if possible.When the BA of the test drugs can’t be determined by detecting the blood-drug concentration, if the primary forms and the active metabolites of the test drugs are mainly be excreted in urine (more than 70% of the dosage), the BA assay may be performed by detecting the urine drug concentration, which is the test of the accumulated excretion quantity of drugs in urine to reflect the intake of drugs. The test products and trial scheme should accord with the demands of BA assay. The urine samples should be collected at intervals, and the collection frequency and intervals of which should meet the demands of evaluating the excretion degree of the primary forms and the active metabolites of the test products in urine. However this method cannot reflect the absorption speed of the drugs and gets many error factors, it is not recommended generally.Some drugs metabolize so rapidly in vivo that it is impossible to detect the primary forms in biological samples. Under these circumstances, the method determining the concentration of corresponding active metabolites in biological samples is adopted to perform the BA and BE studies.(Ⅲ) Result EvaluationAt present, the weighting function of AUC on drug absorption degree is comparatively affirmed, while C max and T max sometimes are not sensitive and seemly enough for weighting the absorption speed due to their dependence on the arrangement of sampling time, and they are therefore not suitable for drug products with multi-peak phenomena and for experiments with large individual variation. During the evaluation, if there are some special instances of inequivalence, a specific analysis should be performed for specific problems.As for AUC，the 90% confidence interval is generally required within the scope of 80%~125%. As for the drugs with narrow treatment spectrum, the above scope should likely be appropriately reduced. While in a few instances, having been validated to be reasonable, the scope can also be increased. So does C max. And as for T max, statistical evaluation is required only when its release speed is closely correlated to clinical therapeutic effects and safety, the equivalence scope of which can be ascertained according to the clinical requirements.When bioavailability ratio of test products is higher than that of reference products, which is called suprabioavailability, the following two instances can be considered: 1). Whether the reference product itself is a product with low bioavailability, which results in the improvement of the test drug's bioavailability; 2). The quality of the reference product meets the requirement, and the test drug really has higher bioavailability.(Ⅳ) Submission of the Contents of Clinical Study ReportsIn order to satisfy the demand of evaluation, a clinical report of bioequivalence study shouldinclude the following contents: (1)Experiment subjective;(2) Establishment of analysis methods for bioavailability samples and data of inspection, as well as provision of the essential chromatograms;(3) Detailed experiment design and operation methods , including data of all the subjects，sample cases，reference products，given dosage，usage and arrangement of sampling time;(4) All data about original measurement of unknown sample concentrations，pharmacokinetics parameters and drug-time curve of each subjects;(5) Data handling procedure and statistical analysis methods as well as detailed procedure and results of statistics;(6) Observation results of clinical adverse reactions after taking medicine，midway exit and out of record of subjects and the reasons;(7) Result analysis and necessary discussion on bioavailability or bioequivalence; (8) References. A brief abstract is required before the main body; at the end of the main body, names of the experiment unit, chief persons of the study and experiment personnel should be signed to take the responsibility for the results of the study.。

蔡司 i-Solution DT-L DT DT-M 用户手册说明书

Features included in i-Solution DT-L/ DT/ DT-M iSolution DT-L is the program focused on core material science applications.iSolution DT has all features for various science and inspection applications.iSolution DT-M is the motorized stage control application version having all features of iSolution DT.It has many new developed functions alsoInclude:Live Measurement and Overlay SettingsUsers can perform measurements on the live preview image, using the crosshair or grid masks to center and count. The grid masks include calibration data. Calibration marker (scale bar) can be placed on the live preview image. The marker (scale bar) can also be burned on each captured image automatically. Anystandard file format image can be chosen to see it above live preview image.Calibration (Auto, Manual)All measurements start with an accurate calibration. Auto, Semi-Auto calibration functions allow the software to calculate the pixels-per-unit value automatically. Only setting the unit for the calibration scale and the distance between the scale marks is needed. This feature greatly improves the accuracy and repetition of measurements. Manual calibrations are easily added and saved for recall from a drop down menu. All calibrations can be saved as files, which let the calibration be retrieved by simply opening the saved files later.Calibration can be protected by password option. Two password options, one in calibration menu itself and the other in camera resolution option, protect calibration by unexpected change. A scale bar can be permanently added to each image. Scale bar properties for color, size and text are simple to optimize for any image background.Z-Axis Extended Focus Imaging (EFI), with displacement compensation for stereo microscopesSamples with curves or of varying heights are difficult to bring into focus under highly magnified conditions. And more a stereomicroscope takes images with tilting due to its own structural characteristics. Thus, each image is out of its supposed position when you move microscope to the Z-axis getting the right focus. Our displacement compensation function allows you to rearrange these images automatically and manually.Software can combine a stack of images sequentially captured at different levels of focus and combine them into a single in-focus image. You can count on our software not to leave any trace of the composites.3D Visualization. . . clearly view complex structuresA Three-dimensional picture can be created from any image. The 3-D presentation is based upon intensity values of the image and can be displayed as a normal or wire frame image. Z axis information can easily be adjusted to optimize the 3-D effect. To better visualize an image in 3-D, software offers full 360 degrees of rotation on X-Y-Z axis. A 3D image can then saved in JPG, TIF or BMP format.Image Stitching. . . create a mosaic of the “Big Picture”With our software, you can create auto and manual composites of continuously captured images in order to minimize the reduction in the field-of-view that typically comes with increased magnification. Combined images are automatically corrected for brightness without leaving any stitching mark. Live Image Comparison. . . for fast inspection and size verificationFor QA testing or quick go/no-go inspections any stored image can be used as a reference image onto which the live preview image is projected.Time Lapse Capture and Movie File Production. . . Import into Power PointSoftware features a Time Lapse Capture function that supports TIF, BMP and JPG file formats. The Time Lapse Capture function also includes an Auto Save feature byyyyy/mm/dd/hour/minute/second. You can save video movie recordings in AVI, MPG, MPEG, and MOV formats.Combine Image Planes - Fluorescence ImagingMerge and pseudo color monochrome images into a single RGB composite.Advanced - Fluorescence Image mergeFluorescence merging function allows several images to one composite image.There is rich list of pre-defined dyes already.One can choose desired emission wavelength in nanometers also and then correspondent color is calculated automaticallyExport Into Excel® - with one mouse clickA single mouse click exports the original image with measurement, calibration, annotation overlay, measurement data, statistics, and chart.Manual Measurement Tools - Including Various Perpendicular DistanceSoftware’s versatile manual measurement features include tools for measuring lengths, areas, and angles and can even auto detect an object's outline and then make specified measurements. The software is equipped with a wide choice of powerful measurement tools including 3-point circle functionality, Npoint circle measurement functionality, parallel line distance measurement, perpendicular distance measurement and object distance measurement. In addition, a zoom-in window can be used to determine the accurate measuring point of an object.Once you've measured a specimen you can easily export all of the images, measurement data and statistics to an Excel® file. With i-Solution DT, comprehensive statistics and data are just one effortless mouse click away.Line ProfilingSingle, multiple, parallel and polyline commands provide Gray/Red/Green/Blue intensity values for specific lines within an image. The profile data of each pixel on the line can be exported to MS Excel. Auto TraceUsing an automatic edge detection algorithm, our software will perform an auto trace measurement function around a closed object. This function greatly increases accuracy and saves time when makingmeasurements of complex shapes.Image ProcessingManual Brightness, Contrast, Gamma, Background Subtraction, Shading Correction, Histogram, Clone, Crop, AOI, Resize, Rotate, Split, Merge Monochrome series into RGB Color, Combine different exposure Images for highlight reduction, Image Mode Change, Grayscale, RGB, HSB, YUV Pseudo Color view, Full range of enhancement and morphology filters 8bit and 16bit per channel Manual MeasurementsPoint Count, Straight Line, Circle by radius, Circle by N points, Circle by diameter, Circle by 3 points, rectangle, polygon, polyline, splice lines from a common point, auto trace, angle parallel lines, perpendicular width, perpendicular from common line, angle between 2 lines, distance, perpendicular distance.Shading CorrectionThe edge parts of captured image by low magnification have background shading frequently, which can be removed by the shading correction function. The color of the original image remains the same though. A standard image is acquired from a blank space on the slide glass, or from an out of focus image in a metallurgical specimen. Such a standard image is used to correct the background shading of all other captured images.AnnotationLine, arrow, polyline, spline, rectangle, ellipse, textRegion of Interest- ROI. . . . with unique add/subtract capabilityRectangle, arbitrary rectangle, circle, arbitrary ellipse, polyline, spline, magic wand ROI itself can be saved to work with other images. The saved ROI can be placed on the exact same location of other images.View and Zoom ImageManual zoom In-Out, User Defined, Fit to Window, 1600% Zoom in Window for Accurate Edge Detect, sizeable context Window to view all open ImagesImage EditingUndo, Redo, Copy, Paste, Paste New, Delete, Delete All, Annotate, Image InformationSave OptionsTXT File Format, image and measurement data together in Proprietary .img File Format for future editing and data collectionSupported Image File Formatsjpg, jpeg, tif, tiff, bmp, gif, pcx, tga, mpg, mpeg, avi, mov, img, rpt, txt and etc.Report GeneratorCreate Report, Insert Image and Data, Insert other OLE ObjectsWindow ViewSplit Horizontal, Split Vertical, Cascade, Tile Horizontal, Tile Vertical, Arrange icons, Dynamic User Interface (UI), Classic, ModernTime Lapse Sequence ControlPlay Forward, Backward, Making Movie File (mpg, avi, mov) with Still Images, Split Single Image from Sequence FileAuto/Manual Thresholding for Count and SizeIntensity and color based thresholding tools for identifying, counting and categorizing objects.Ideal for automatic objects counting and percentage of area measurements.Objects Editing… enhanced measurement accuracy!Target threshold objects can be edited by all measurement parameters or with filters to clean, close, open, dilate, erode, automatic separate and fill holes.Densitometryi-Solution software automatically calculates Optical Density (OD) by absolute and relative figures, semi automatically, or manually based on user configuration. Images and OD figures can then be exported directly to an MS PowerPoint file.Perfect Focus Enhancementi-Solution implements a perfect function of focus compensation irrespective of the status of lights and specimen.Macro-Enabled RecordingCreate and save customized measurement settings and sequencesData CollectorSelect desired measurements then easily collect and tabulate data from multiple samples. Reflected Light Subtractioni-Solution creates clear, evenly illuminated images by removing the bright saturated light from a highly reflective sample.Automatic count for live and stained cellsConglomerated live and stained cells are separated automatically and counted.Particle AnalysisParticle data in many images is given by statistics and individual form. Each object is viewed with data together.Phase Analysis & Advanced Thresholdi-Solution conducts phase analysis on an entire image or within a specified Region of Interest (ROI) and it can allow to sort images using Gray Scale, RGB, HSB or YUV.Thickness Measurement (Layer Depth Measurement)Average thickness is measured automatically by defining box. The number of scan lines can be defined by users.Stereometry for BiovolumeThe 3D volume of an object is calculated by using 2D measuring parameters.67 selectable measurement parametersA complete menu of measurement types with a description of the parameter3D reconstructionA 3D rendering picture can be created from Z stacked images. A real 3D rendering picture is made by many Z stacked images. The 3-D presentation can be displayed as a normal or wire frame image. To better visualize an image in 3-D, software offers full 360 degrees of rotation on X-Y-Z axis. A 3D image can then saved in JPG, TIF or BMP format.Illuminator controlProgram controls illuminator shutter.Live cell countLive cells having irregular shape can be counted automatically, which can be hardly possible by ordinary thresholding method.Grain Size MeasurementiSolution DT provides the standard measurement environment in structure analysis of metal and materials according to ASTM E112 (2000). Both intercept lines and planimetric counting are available.Ferrite in Cast IronPercent Ferrite is calculated by excluding the graphite area. Graphite can be sorted for calculation including portions with the same gray intensity value of the background pearlite.Graphite Analysis in Nodular Cast IroniSolution DT may automatically generate measured data on the international standards regarding the cast iron. It provides graphite types and nodularity data according to the international standards such as ASTM A247-67 (1998), ISO 945 (1975), JIS G5502 (2001), KSD4302 (2002) with a single click. Chart NavigatorThe Chart Navigator permits direct comparison between the live or captured image and a series of reference images. The user-friendly interface makes you quickly find the image you need which matches or is similar to the live or captured image out of a large number of reference images. Both the live image and the reference image can be exported to MS Excel by simple mouse click. Synchronize zoom function makes it enable to see the same view size whatever zoom ratio the live or captured image has.Particle analysisIt gives particle analysis result with each object shape and statistic data.The below features are included in iSolution DT and DT-M only, not in DT-L Non-metallic Inclusion RatingThe functions in iSolution DT is intended to determine the inclusion content of steel according ASTM E45 (2002), ASTM E1122 (1996), DIN 50602 (1985), ISO 4967(1998), KSD 0204 (2002), JIS G0555 (2003). Two analysis approaches, Stereological measurements and JK inclusions ratings are implemented.Yarn filament analysisThe function is intended for processing a narrow class of special images with filament objects. There are four types of filament objects supported by the program: triangle, circles, FD circle, and polygon. Automatic Fruit Size AnalysisIt measures fruit size automatically.Volume fraction based on ASTM E562-05It gives the volume fraction of residual Austenite and Ferrite based on ASTM E562-05Rust Analysis based on ASTM D610-08 and JIS H 8681-2It gives the rust analysis result based on ASTM D610-08 and JIS H 8681-2Microindentation hardnessIt gives microindentation hardness test result based on Knoop and Vickers.The below features are included in iSolution DT-M onlyMotorized stage controliSolution DT-M controls motorized stage of Marzhauser, Ludl, Prior scientific, and ASIVirtual microscopeWith motorized control stage, it gives automatic image stitching for scanning whole slide area. While making a whole large area image, image stitching and microscope focus enhancement can be done at the same time. Even with stereomicroscope, such a function is available.Image analysis with automatic image stitchingImage analysis with data collector can be done having automatic image stitching at the same time. Image analysis data can be achieved while making a large stitched image by motorized control stage, which gives analysis data and whole picture at the same time.Automatic focus adjustmentWhile stage is moved, focus is adjusted automatically by software function alone, not with any other additional hardware device.Banding analysis based on ASTM E1268It gives banding analysis result based on ASTM E1268 standard.Adding customized modules by requestSystem Requirements• PC with a Pentium-class processor; Pentium 300MMX or higher recommended• Microsoft Windows Win7/Vista/WinXP/2000/ME/Win98SE operating system• 32 MB of RAM or more (128 MB recommended)• 15 MB or more hard-disk space (50 MB recommended)• CD-ROM drive• VGA or higher-resolution monitor; Super VGA recommended (1024 x 768 pixel and 24 bit and more color support video card is recommended)• Microsoft Mouse or compatible pointing device• USB- or LPT-port for hardware key (depends on delivery).Supported imaging devices1. TWAIN Driver2. DirectShow/ WDM (Windows driver mode) driver3. i-Link DevicesAll PixeLINK cameras.Optronics digital cameras- MicroFire- MacroFire- QuantiFire and QuantiFire XI- Microcast- All MPX series cameras- All QPX series camerasJenoptik ProgRes digital cameras- C3 (cooled and non-cooled)- C5 (cooled and non-cooled)- C14- ProgRes CF and CFScan (cooled, non-cooled, and scan)- ProgRes MF (cooled, non-cooled, and scan)-ProgRes all CMOS cameras.Nikon digital cameras- DS-U2 Fi1- DS 5M/2M-U2- DS 5M/2M-U1- DXM 1200C- DXF 1200FPixera digital camera- Penguin series all models- Pro series all modelsScion corporation digital camera-CFW series all modelsMatrix vision-mvBlueFox digital cameraArtray- ARTCAM-500MI- ARTCAM-300MI- ARTCAM-200MI- ARTCAM-130MI (color, mono, and NIR) - ARTCAM-036MI (color, mono, and TWIN) - ARTCAM-500P- ARTCAM-200SH- ARTCAM-150P-II (color and mono)- ARTCAM-098 (color and mono)- ARTCAM-34MCLumenera- Infinity 1 series all models- Infinity 2 series all models- Infinity 3 series all models- Infinity X and Infinity X-21XLi camera- M series cameras- DC series cameras- DX series camerasSpot digital camera- Insight- FlexQimaging digital cameras- MicroPublisher- RetigaAll Leica digital cameras by TWAINCarl Zeiss AxioCam by TWAINFlashBus frame grabber- Spectrim Lite- Spectrim Pro- MV LiteMatrox frame grabber- Meteor IIAvermedia frame grabber- EZMakerConsumer digital camerasIMT i-Solution Inc. 。

传感器术语

GlossaryABSOLUTE PRESSURE: The pressure measured relative to a perfect vacuum.ABSOLUTE PRESSURE TRANSDUCER: A transducer that has an internal reference chamber sealed at or close to 0 psia (full vacuum).ACCURACY: The ratio of the error to the output or to the full scale output, as specified, expressed in percent.ATMOSPHERIC PRESSURE: The pressure caused by the weight of the earth’s atmosphere; varies with geographic location, altitude, and weather.BAROMETRIC PRESSURE: See ATMOSPHERIC PRESSURE.BEST STRAIGHT LINE: The line parallel to, and centered between, two parallel straight lines enclosing all calibration data points.BRIDGE: A Wheatstone bridge configuration utilizing four resistive elements.BRIDGE RESISTANCE: See INPUT IMPEDANCEand OUTPUT IMPEDANCE.CALIBRATION: The comparison of transducer voltage outputs against the outputs of a reference standard.COMMON MODE PRESSURE: See LINE PRESSURE.CONSTANT CURRENT: Electric current independent of either voltage or resistances and fixed at a specific value. A constant current ower supply varies its output voltage, up to its maximum compliance voltage, to maintain the fixed current into the load.DAMPING: The reduction of response at the resonance frequency through the use of a damping medium such as oil. Usually specified as the ratio to the critical damping.DEAD VOLUME: The volume inside the pressure port of a transducer at room temperature and barometric pressure.DEFLECTION: The change in length along the primary axis or the distance a diaphragm moves at the center between no-load and rated-load conditions. DIAPHRAGM: The sensing membrane which is deformed when pressure is applied. DIFFERENTIAL PRESSURE: The difference in pressure between two measurement points.DYNAMIC PRESSURE: See IMPACT PRESSURE.ENDEVCO: An acronym for ENgineering DEVelopment COmpany. A leader in developing instrumentation for the sensing of physical phenomena.EXCITATION, ELECTRICAL: The voltage or current applied to the input terminals of the transducer.FLUSH DIAPHRAGM: Sensing element is located on the very tip of the transducer (No pressure port).FREQUENCY RESPONSE: The range of frequencies over which the transducer voltage output will follow a sinusoidally varying mechanical input within specified limits.FULL SCALE: The maximum measurand that a transducer is designed to measure within its specification.FULL SCALE OUTPUT: The algebraic difference between the output with zero input and output with full scale input (range) applied.GAGE PRESSURE: The pressure above (or below) atmospheric. Represents positive difference between measured pressure and existing atmospheric pressure. Can be converted to absolute by adding actual atmospheric pressure value.HYSTERESIS: The maximum difference between output readings for the same measurand point, one point obtained while increasing from zero and the other while decreasing from full scale. The points are taken on the same continuous cycle. The deviation is expressed as a percent of full scale.IMPACT PRESSURE: The pressure in a moving fluid which is exerted parallel to the direction of flow, caused by the inertial effects of the mass of the fluid. Also called DYNAMIC PRESSURE or VELOCITY PRESSURE.INDEPENDENT LINEARITY: Maximum deviation from the linear regression line (least squares fit) for all measured points, expressed as percent of full scale output. INPUT IMPEDANCE: The resistance measured across the excitation terminals of a transducer at room temperature.INSULATION (ISOLATION) RESISTANCE: The DC resistance, expressed in ohms, measured between any electrical connector pin or lead wire and the transducer bodyor case. Normally measured at 50 Vdc.LINEARITY: The maximum deviation of the calibration curve from a specified straight line expressed as a percent of full scale output and only measured on increasing measurand.LINE PRESSURE: The maximum pressure in the pressure vessel or pipe for differential pressure measurement. Also called COMMON MODE PRESSURE. MEASURAND: The physical quantity, property, or condition which is measured. (e.g.: pressure, load, weight, acceleration).MEDIUM (MEDIA): The fluid(s) in contact with the diaphragm, the pressure of which is being measured.NONLINEARITY: Used interchangeably with “linearity.”NONREPEATABILITY: Used interchangeably with “repeatability.”OUTPUT: The electrical signal measured at the output terminals which is produced by an applied input to a transducer.OUTPUT IMPEDANCE: The resistance as measured on the output terminals of a transducer at standard temperature, with no measurand applied, and with the excitation terminals open-circuited.OVERRANGE: The maximum pressure or load which may be applied to the transducer without causing a permanent change in the performance specifications.PARTIAL PRESSURE: The pressure which would be exerted by one constituent of a mixture of gases, if it alone were to occupy the same volume as the mixture. See also TOTAL PRESSURE.PASCAL: Pressure of one Newton (force) per square meter.PHASE SHIFT: The phase angle between the output and the applied signal.PRESSURE HEAD: The height of a liquid column at the base of which a given pressure would be developed due to gravity acting on the fluid mass.PSI: Pounds per square inch.PSIA: Pounds per square inch absolute.PSID: Pounds per square inch differential.PSIG: Pounds per square inch gage.RANGE: The measurand values, over which a transducer is intended to measure, specified by their upper and lower limits.REFLECTED OVERPRESSURE: The total pressure that results at the interface when a shock wave traveling in a medium encounters a discontinuity such as a rigid surface or another shock wave.REPEATABILITY: The ability of a transducer to reproduce output readings when the same measurand value is applied to it consecutively, under the same conditions, and in the same direction. Repeatability is expressed as the maximum difference between output readings as a percent of full scale.RESOLUTION: A measure of ability to delineate, detail, or distinguish between nearly equal values of quantity. Also referred to as “threshold” – lowest level of valid measurement.RESPONSE TIME: The time required for the output of a transducer to increase from zero to some specified percentage of its final value when excited by a step change in measurand.RISE TIME: The time required for the output of a transducer to rise from 10% to 90% of its final value as a result of a step change of measurand.SEALED (or SEALED GAGE) PRESSURE: Pressure measured with reference to the pressure in a sealed container; the container is usually within the sensor.SENSING ELEMNT: The part of the transducer which reacts directly in response to the measurand.SENSITIVITY: The ratio of change in transducer output to a change in the value of the measurand. Specified sensitivity is usually averaged over the full scale range of the measurand.SHUNT CALIBRATION: The change in electrical output caused by placing a fixed resistor between the appropriate transducer terminals. Used “in the field” for quick calibration.S.I. SYSTEM: The international (metric) system of units.SPAN: The algebraic difference between the limits of the range from zero to full scale. SPECIFICATIONS: The group of error limits within which each device will operate. STAGNATION PRESSURE: The sum of the static pressure and the impact pressure. It can be measured at a point where the velocity of the fluid is zero.STANDARD PRESSURE: Pressure of one normal (standard) atmosphere, defined (in the United States and some other countries) as 101.325 kPa (14.696 psia).STATIC PRESSURE: The pressure of a fluid, exerted normal to the direction along which the fluid flows.STRAIN GAGE: A measuring element for converting mechanical strain into an electrical signal.SUPPLY VOLTAGE: See EXCITATION.TEMPERATURE COEFFICIENT: The percentage change in the sensitivity of a transducer as a result of a change in the operating temperature of the transducer (expressed as percent per degree [%/ºF]).TEMPERATURE COMPENSATED: The range of temperature over which a transducer can operate up to full scale and still meet all specifications.Meggitt’s Endevco pressure transducers incorporate temperature compensation.TEMPERATURE COMPENSATION: The utilization of supplementary devices, materials, or components with the transducer to minimize sources of error caused by changing temperature.TERMPERATURE, OPERATING: The range of temperature over which a transducer may be safely operated up to full scale without causing failure; but specifications may not be met.THERMAL SENSITIVITY SHIFT: The change in sensitivity due to a change in ambient temperature. Usually expressed as the maximum percentage change in sensitivity.THERMAL ZERO SHIFT: The change in zero balance due to a change in ambient temperature. Usually expressed as the maximum percentage change of FSO over the compensated temperature range.TOTAL PRESSURE: The sum of the pressures (partial pressures) which each gas (in a mixture of gases) would exert were it to occupy the containing vessel alone. TRANSDUCER: A device (or medium) that converts energy from one form to another. The term is generally applied to devices that take a physical phenomenon (pressure, temperature, humidity, flow, etc.) and convert it to an electrical signal.VACUUM: Pressure measured below atmospheric pressure and with reference to atmospheric pressure (Negative gage pressure).VELOCITY PRESSURE: See IMPACT PRESSURE.ZERO ADJUSTMENTS: Used when “setting up” a transducer to adjust the output signal to zero when zero load/pressure is applied.ZERO BALANCE: The output signal of the transducer with rated excitation and with no-load applied, usually expressed in millivolts. Also called ZMO and zero pressure output.ZERO RETURN: The difference in zero balance measured immediately before rated load application of specified duration and measured after removal of the load, and when the output has stabilized.。

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