Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a Mach-Zehnder three-grating interferometer are analyzed. Alternatively to atom-photon entanglement scenarios, the model considered here only relies on the atomic wave function and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. A good quantitative agreement is found when comparing the results obtained from our model with the experimental data.Comment: 18 pages, 4 figure

THE PURPOSES AND METHODS OF ENERGY SYSTEM MODELING

U radu je opisana svrha modeliranja energetskog sustava i podjela modela za planiranje s obzirom na različitosti pristupa i metodologije. Pojava modernih računala i razvoj računalnih programa pojednostavnila je korištenje modela za planiranje. Ovakvi modeli koriste snažne matematičke algoritme i baze podataka koji u relativno kratkom vremenu mogu riješiti vrlo složene probleme. To je dalje omogućilo nastanak tzv. E3 modela (engl. energy-ecology-economy) koji imaju mogućnost istodobnog sagledavanja pitanja vezanih za energetiku, ali i za ekologiju i ekonomiju. Posebno su prikazane karakteristike modela MARKAL kroz primjer integriranog povezivanja s drugim modelima za planiranje. Pokazuje se da je primjena optimizacijskog modela MARKAL za planiranje energetskog sustava Republike Hrvatske od velikog značenja s obzirom na potrebne analize energetskog tržišta jugoistočne Europe, korištenja obnovljivih izvora energije, energetsku učinkovitost i trgovine emisijama.This article describes the purpose of energy system modeling and the classification of planning models according to approaches and methodologies. The advent of modern computers and computer programs has simplified the use of planning models. Such models employ powerful mathematical algorithms and databases which can solve highly complex problems in a relatively short time. This has led to energy-ecology-economy (E3) models, which are simultaneously able to consider questions in connection with energy supply, ecology and economics. The characteristics of a MARKAL model are presented separately through an example of integration with other planning models. It is demonstrated that the application of an optimizing MARKAL model for the planning of the energy supply system of the Republic of Croatia is of great significance for the analysis of the energy market of South East Europe, the use of renewable energy sources, energy efficiency and emission tradin

THE PURPOSES AND METHODS OF ENERGY SYSTEM MODELING

U radu je opisana svrha modeliranja energetskog sustava i podjela modela za planiranje s obzirom na različitosti pristupa i metodologije. Pojava modernih računala i razvoj računalnih programa pojednostavnila je korištenje modela za planiranje. Ovakvi modeli koriste snažne matematičke algoritme i baze podataka koji u relativno kratkom vremenu mogu riješiti vrlo složene probleme. To je dalje omogućilo nastanak tzv. E3 modela (engl. energy-ecology-economy) koji imaju mogućnost istodobnog sagledavanja pitanja vezanih za energetiku, ali i za ekologiju i ekonomiju. Posebno su prikazane karakteristike modela MARKAL kroz primjer integriranog povezivanja s drugim modelima za planiranje. Pokazuje se da je primjena optimizacijskog modela MARKAL za planiranje energetskog sustava Republike Hrvatske od velikog značenja s obzirom na potrebne analize energetskog tržišta jugoistočne Europe, korištenja obnovljivih izvora energije, energetsku učinkovitost i trgovine emisijama.This article describes the purpose of energy system modeling and the classification of planning models according to approaches and methodologies. The advent of modern computers and computer programs has simplified the use of planning models. Such models employ powerful mathematical algorithms and databases which can solve highly complex problems in a relatively short time. This has led to energy-ecology-economy (E3) models, which are simultaneously able to consider questions in connection with energy supply, ecology and economics. The characteristics of a MARKAL model are presented separately through an example of integration with other planning models. It is demonstrated that the application of an optimizing MARKAL model for the planning of the energy supply system of the Republic of Croatia is of great significance for the analysis of the energy market of South East Europe, the use of renewable energy sources, energy efficiency and emission tradin

ENERGY EFFICIENCY INDICATORS

U radu su opisani indikatori energetske učinkovitosti i indeksi poboljšanja energetske učinkovitosti prema vrsti i namjeni. Namjena indikatora i indeksa je praćenje i uspoređivanje trendova energetske učinkovitosti u zemljama EU- 27, Norveškoj i Hrvatskoj, stoga su posebno prikazani trendovi u Hrvatskoj za svaki od sektora potrošnje energije.This paper describes energy efficiency indicators and indices of energy efficiency improvements according to type and use. The purpose of indicators and indices is the monitoring and comparing of energy efficiency trends in the EU-27 countries, Norway and the Republic of Croatia, therefore the trends in Croatia have been specially presented for each of the energy consumption sectors

On the influence of resonance photon scattering on atom interference

Here, the influence of resonance photon-atom scattering on the atom interference pattern at the exit of a three-grating Mach-Zehnder interferometer is studied. It is assumed that the scattering process does not destroy the atomic wave function describing the state of the atom before the scattering process takes place, but only induces a certain shift and change of its phase. We find that the visibility of the interference strongly depends on the statistical distribution of transferred momenta to the atom during the photon-atom scattering event. This also explains the experimentally observed (Chapman et al 1995 Phys. Rev. Lett. 75 2783) dependence of the visibility on the ratio d_p/\lambda_i = y'_{12} (2\pi/kd\lambda_i), where y'_{12} is distance between the place where the scattering event occurs and the first grating, k is the wave number of the atomic center-of-mass motion, $d$ is the grating constant and \lambda_i is the photon wavelength. Furthermore, it is remarkable that photon-atom scattering events happen experimentally within the Fresnel region, i.e. the near field region, associated with the first grating, which should be taken into account when drawing conclusions about the relevance of "which-way" information for the interference visibility.Comment: 9 pages, 1 figur

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cyg

Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornestones to critical tests of stellar evolution theory for massive stars. Yet, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyze all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analyzed earlier obtained blue electronic spectra. Our analyses provide the most accurate so far published value of the apsidal period of 47.805 +/- 0.030 yrs and the following physical elements: M1=17.72+/-0.35$ Msun, M2=17.73+/-0.30 Msun, R1=5.785+/-0.091 Rsun, and R2=5.816+/-0.063 Rsun. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = -1.937. A comparison with Claret's stellar interior models implies an age close to 2 millions yrs for both stars. The claimed accuracy of modern element determination of 1-2 per cent seems still a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.Comment: 13 pages; accepted for publication in Astronomy and Astrophysic

Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries

Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is a very hard task, however, which is complicated by the presence of circumstellar matter in these systems. So far, only a small number of systems with accurate values of component masses, radii, and other properties are known. Here, we report the first detailed study of a new representative of this class of binaries, BR CMi, based on the analysis of radial velocities and multichannel photometry from several observatories, and compare its physical properties with those for other well-studied systems. BR CMi is an ellipsoidal variable seen under an intermediate orbital inclination of ~51 degrees, and it has an orbital period of 12.919059(15) d and a circular orbit. We used the disentangled component spectra to estimate the effective temperatures 9500(200) K and 4655(50) K by comparing them with model spectra. They correspond to spectral types B9.5e and G8III. We also used the disentangled spectra of both binary components as templates for the 2-D cross-correlation to obtain accurate RVs and a reliable orbital solution. Some evidence of a secular period increase at a rate of 1.1+/-0.5 s per year was found. This, together with a very low mass ratio of 0.06 and a normal mass and radius of the mass gaining component, indicates that BR CMi is in a slow phase of the mass exchange after the mass-ratio reversal. It thus belongs to a still poorly populated subgroup of Be stars for which the origin of Balmer emission lines is safely explained as a consequence of mass transfer between the binary components.Comment: 17 pages, 5 figures, accepted for publication in Astronomy and Astrophysics. appears in Astronomy and Astrophysics 201

Short period line profile and light variations in the Be star ω Orionis

We present the results of a multisite spectroscopic and photometric campaign on the Be star ω Orionis. From the photometry and radial velocity variation of several spectral lines, we confirm that the star is a variable with period . Only one period can be extracted from both the photometric and radial velocity observations. We find that the projected rotational velocity from the helium lines is considerably smaller than from the metal lines . The line profiles show an excess absorption feature moving from blue to red for half the period and from red to blue for the other half of the period. Another excess absorption feature moves exactly out of phase. The excess absorption features are present in photospheric lines as well as in lines which are significantly affected by circumstellar material, such as Hβ. From this we conclude that the periodic variations are most probably associated with corotating circumstellar materia