scholarly journals Measure by Measure, they touched the heaven

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 265
Author(s):  
Luisa Spairani
Keyword(s):  
Classification System ◽  
Double Star ◽  
Indelible Mark ◽  
Special Mention ◽  
Italian Women ◽  
Star Classification

The measure of distances is a recurring theme in astrophysics. The interpretation of the light coming from a luminous object in the sky can be very different depending on the distance of the object. Two stars or galaxies may each have a different real brightness, although they may look similar. The correct measures were determined by women computers a century ago. Special mention is due to Williamina Fleming, who supervised an observatory for 30 years and worked on the first system to classify stars by spectrum. Antonia Maury helped locate the first double star and developed a new star classification system. Henrietta Leavitt determined a law to calculate stellar distances. The most famous of the Harvard computers was Annie Jump Cannon. An expert in photography, she catalogued over 350,000 stars and expanded the classification system used today, but it was Henrietta Leavitt who left an indelible mark by discovering a law for the determination of stellar distances. In the same period, Italian women computers began to collaborate in observatories, but their tracks are obfuscated.

scholarly journals Study of Dual Stator Induction Motor in Photovoltaic-Fuel Cell Hybrid Pumping Application

2020 ◽  
Vol 53 (5) ◽  
pp. 601-608
Author(s):  
Arezki Adjati ◽  
Toufik Rekioua ◽  
Djamila Rekioua ◽  
Abdelmounaim Tounzi
Keyword(s):  
Fuel Cell ◽  
Induction Motor ◽  
Centrifugal Pump ◽  
Cell Hybrid ◽  
Double Star ◽  
Water Requirements ◽  
Matlab Simulink ◽  
Pumping System ◽  
Dynamic Head

This paper discusses the modeling of hybrid Photovoltaic/Fuel cell pumping. This system comprises a photovoltaic generator and a fuel cell, two DC/DC converters, two of inverters which supply a double star induction motor (DSIM) which drives the shaft of a centrifugal pump. The evaluation of the water requirements, the total dynamic head (TDH) and the flow are of great importance to evaluate the various powers allowing the determination of the size of the pumping system. The global proposed system is sized and simulated under Matlab/Simulink Package. The obtained results under different metrological conditions show the effectiveness of the proposed hybrid pumping system.

scholarly journals Seeing Compensation in Photoelectric Area Scanning

1977 ◽  
Vol 33 ◽  
pp. 33-33
Author(s):  
O. G. Franz
Keyword(s):  
Relative Position ◽  
Accurate Determination ◽  
Angular Separation ◽  
Double Star ◽  
Optical Image

AbstractA method is described which, through the use of an optical image rotator in conjunction with an area scanner, allows the accurate determination of the magnitudes and relative position of the components of a double star even if the angular separation is significantly smaller than the radius of the seeing disk.

scholarly journals Hipparcos, Three Years After Launch

1993 ◽  
Vol 156 ◽  
pp. 1-10
Author(s):  
J. Kovalevsky ◽  
M. Froeschlé
Keyword(s):  
Standard Error ◽  
Present Status ◽  
Double Star ◽  
New Method ◽  
Standard Errors ◽  
First Year ◽  
Mass Determination ◽  
Mission Duration ◽  
The Mean

In a first part, the present status of the HIPPARCOS mission is described. Despite the degradations and failures of gyroscopes, it is still hoped that a 4 1/2 mission duration will be reached. The first-year of data has been reduced by both FAST and NDAC consortia. For the best 46200 observed stars, the distribution of standard errors in positions has a maximum of 1.5 mas in latitude and 1.8 mas in longitude and the mean standard error for parallaxes is of the order of 3 mas. The comparison of results obtained by both consortia shows that the differences are small and quite consistent with the announced internal precisions. Magnitude measurements are precise to 0.02 magnitude for a 4 second observation. The precision to be expected for double star observations is also given. The main new result is that the magnitudes of the components are obtained with a few hundredths of a magnitude precision. This allows to devise a new method of mass determination based upon the parallax and a recalibrated mass-luminosity diagram. The parallax dependence of the results is much more favourable than in the case of the classical determination of masses using orbital motions.

Supervised Star Classification System for the OMC Archive

2010 ◽  
pp. 509-509
Author(s):  
Mauro López ◽  
Luis M. Sarro ◽  
Enrique Solano ◽  
Raul Gutiérrez ◽  
Jonas Debosscher
Keyword(s):  
Classification System ◽  
Star Classification

scholarly journals Globular cluster star classification: Application to M13

2013 ◽  
pp. 25-45
Author(s):  
R. Caimmi
Keyword(s):  
Chemical Evolution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Selection Criterion ◽  
Oxygen Depletion ◽  
Differential Abundance ◽  
Linear Fit ◽  
Sodium Abundance ◽  
Star Classification

Starting from recent determination of Fe, O, Na abundances on a restricted sample (N = 67) of halo and thick disk stars, a natural and well motivated selection criterion is defined for the classification globular cluster stars. An application is performed to M13 using a sample (N = 113) for which Fe, O, Na abundances have been recently inferred from observations. A comparison is made between the current and earlier M13 star classifications. Both O and Na empirical differential abundance distributions are determined for each class and for the whole sample (with the addition of Fe in the last case) and compared with their theoretical counterparts due to cosmic scatter obeying a Gaussian distribution whose parameters are inferred from related subsamples. The occurrence of an agreement between the empirical and theoretical distributions is interpreted as absence of significant chemical evolution and vice versa. The procedure is repeated with regard to four additional classes depending on whether oxygen and sodium abundance is above (stage CE) or below (stage AF) a selected threshold. Both O and Na empirical differential abundance distributions, related to the whole sample, exhibit a linear fit for the AF and CE stage. Within the errors, the oxygen slope for the CE stage is equal and of opposite sign with respect to the sodium slope for AF stage, while the contrary holds when dealing with the oxygen slope for the AF stage with respect to the sodium slope for the CE stage. In the light of simple models of chemical evolution applied to M13, oxygen depletion appears to be mainly turned into sodium enrichment for [O/H]? -1.35 and [Na/H]? -1.45, while one or more largely preferred channels occur for [O/H]< -1.35 and [Na/H]> -1.45. In addition, the primordial to the current M13 mass ratio can be inferred from the true sodium yield in units of the sodium solar abundance. Though the above results are mainly qualitative due to large (-+1.5 dex) uncertainties in abundance determination, still the exhibited trend is expected to be real. The proposed classification of globular cluster stars may be extended in a twofold manner, namely to: (i) elements other than Na and Fe and (ii) globular clusters other than M13.

scholarly journals Expansion of a Plasmid Classification System for Gram-Positive Bacteria and Determination of the Diversity of Plasmids in Staphylococcus aureus Strains of Human, Animal, and Food Origins

2012 ◽  
Vol 78 (16) ◽  
pp. 5948-5955 ◽  
Author(s):  
Carmen Lozano ◽  
Lourdes García-Migura ◽  
Carmen Aspiroz ◽  
Myriam Zarazaga ◽  
Carmen Torres ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Classification System ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Content Type ◽  
Plasmid Content ◽  
Gram Positive Bacteria ◽  
Human Animal ◽  
Different Origins

ABSTRACTAn expansion of a previously described plasmid classification was performed and used to reveal the plasmid content of a collection of 92Staphylococcus aureusstrains of different origins.repgenes of other genera were detected inStaphylococcus. S1 pulsed-field gel electrophoresis (PFGE) hybridizations were performed with 18 representativeS. aureusstrains, and a high number of plasmids of different sizes and organizations were detected.

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