120 research outputs found
Spectroscopic binaries with elliptical orbits
The radial velocity curves of many spectroscopic binaries (SBs) are perturbed
by gas streams or proximity effects. For SBs with circular orbits, these
perturbations can give rise to spurious orbital eccentricities of high
statistical significance. But tests to identify such anomalous orbits can be
constructed since perturbed velocity curves are in general no longer Keplerian.
The derived tests are applied both to synthetic and to observed velocity
curves.Comment: 9pages,3figures,accepted by A&
Bayesian inference for orbital eccentricities
Highest posterior density intervals (HPDI's) are derived for the true
eccentricities of spectroscopic binaries with measured values e ~ 0. These
yield upper limits when e is below the detection threshold e_th and seamlessly
transform to upper and lower bounds when e > e_th. In the main text, HPDI's are
computed with an informative eccentricity prior representing orbital decay due
to tidal dissipation. In an appendix, the corresponding HPDI's are computed
with a uniform prior and are the basis for a revised version of the
Lucy-Sweeney test, with the previous outcome e = 0 now replaced by an upper
limit. Sampling experiments with known prior confirm the validity of the
HPDI's.Comment: 7 pages, 6 figures. Error in terminology corrected. Results
unchanged. Accepted by Astronomy & Astrophysic
Industrijska fotografija - svijet rada i proizvodnje
Pojava industrijske, dokumentarne fotografije datira iz druge polovice 19. st., ali ni do danas nije u potpunosti istražena. RijeÄ je o posebnom podruÄju primijenjene fotografije u kojemu je sadržaj važniji od forme i koje pruža manje moguÄnosti za osobno izražavanje fotografa i njegovu umjetniÄku kreativnost. NajÄeÅ”Äe je nastajala prema narudžbi poslovnih subjekata ili države, unutar tvornice ili postrojenja, a na njoj su motivi industrijskih kompleksa, tvorniÄkih pogona, proizvodnih procesa, radnika u radnom okružju i konaÄnih rezultata proizvodnje. Angažirani fotograf mora potpuno ovladati fotografskom tehnikom i dobro poznavati materiju snimanja. Primjenjuje se za razliÄite svrhe: za predstavljanje tvornice ili industrijskog kompleksa javnosti, kao sastavni dio obavijesti za razliÄite medije i za izradu promotivnih materijala
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