ODESSA

About: ODESSA is a based out in . It is known for research contribution in the topics: Population & Stars. The organization has 8058 authors who have published 8092 publications receiving 63228 citations.

Conceptual design of binary/multicomponent fluid ejector refrigeration systems

Abstract: Low energy efficiency and limitations of cooling temperatures in the ejector refrigeration systems (ERSs) are major obstacles for its widespread use. The application of binary or multicomponent fluids may prove to be one of the successful ways to increase the ERS performance by 30–50%. Zeotropic mixtures, which have unlimited solubility and evaporate at specified pressures and varying temperatures, are considered as possible candidates to be applied in a binary-fluid ERS (BERS). An ideal candidate working fluid should exhibit high molecular weight, low latent heat of evaporation, high normal boiling temperature and high compressibility factor. A refrigerant fluid should have low molecular weight, high latent heat of evaporation, low boiling point and compressibility factor. BERS pursues simultaneous achievement of two main goals: increase in system's efficiency and take the condensation point up to 45–50°C at fixed coefficient of performance, i.e. employ atmospheric condenser in ERS. This article presents schematic diagrams of a multicomponent-fluid ERS; its cascade principle based on BERS enables to produce cold at several temperature ramps, using renewable or low-grade heat sources. Research outcomes from this article can improve the effective application of ejector technology.

The eclipsing binary star RZ Cassiopeiae - II. Spectroscopic monitoring in 2006

Abstract: Aims. We test the hypothesis that the oEA star RZ Cas has undergone a transient phase of rapid mass-transfer in 2000/2001. Methods. We analyze a time series of high-resolution spectra of RZ Cas obtained in 2001 and in 2006 for radial velocity (RV) and line profile variations. Improved orbital solutions are determined using the method of differential corrections. In the RV residuals, after subtracting the orbital solution and low-frequency variations, we search for non-radial pulsations in the high-frequency domain and for an amplitude modulation of the pulsation modes.We model the observed line profiles using a new computer program based on the method of spectroscopic eclipse mapping and investigate the line intensity residuals and the Rossiter-McLaughlin effect. Results. Between 2001 and 2006, the derived orbital solutions show an increase of the orbital period of the order of 2 seconds that is compatible to the photometrically obtained results. RZ Cas changed its pulsation pattern again. We find at least three pulsation frequencies where one is observed for the first time. All three frequencies show amplitude modulations that are correlated with the position of the star in its orbit. The amplitude amplification around primary minimum is much stronger than in 2001. The modeling of line profiles gives hints to a much more complex and inhomogeneous circumbinary gas density distribution in 2001 compared to 2006. The Rossiter-McLaughlin effect is strongly asymmetric in 2001 and almost normal in 2006. Conclusions. The findings support the assumption that a rapid mass-transfer episode occurred in RZ Cas in 2000/2001.

Thermal bioclimate and climate tourism analysis for odessa, black sea

Abstract: Climate is a main component of nature that, in addition to being a valuable resource, determines the possibility of development of tourism. Apparently, climate and its characteristics determine tou...

Anion Exchange Resin Modified with Nanoparticles of Hydrated Zirconium Dioxide for Sorption of Soluble U(VI) Compounds

Abstract: Organic–inorganic sorbents have been synthesized by modification of gel-like anion exchange resin with hydrated zirconium dioxide. Such synthesis conditions as solution concentration, temperature, and surface tension of the solvent were varied. A theoretical approach, which is based on the Ostwald–Freundlich equation, has been developed for purposeful control of size of the incorporated particles. Depending on the synthesis method, particles of one or other size dominate in the polymer matrix (from ≈5 nm to several microns). Sorption of uranyl anionic complexes was investigated. It was found that sorption rate is described by models of chemical reactions of pseudo-first or pseudo-second order. The samples modified with small particles (from several nanometers up to 300 nm) show higher sorption rate than the pristine resin. Decrease of particle size facilitates chemical regeneration of the sorbents. Desorption degree reaches 95–100%, when 1 M NaHCO3 solution is used.

Light element abundances in the young open clusters NGC 3293, NGC 4755 and NGC 6231: Tracers of stellar evolution

Abstract: The abundances of He (LTE), C, N, and O (NLTE) were derived for 21 B stars in three young open clusters. Almost all the stars show subsolar CNO abundances. However, the mean oxygen abundance for each programme cluster appears to be in marginal agreement with the most recent revisions of the solar value. After consideration of the CN abundances in this sample, there is no clear evidence of internal mixing. Only three stars among the non-supergiants seem to show a nitrogen enhancement. Two of them have a fairly low projected equatorial velocity (admittedly, they may be rapid rotators seen pole-on); the third one is a denite fast rotator. In the lower gravity stars (three stars in this sample with log g< 3:0) some kind of mixing has apparently occurred. The supergiants do not dier signicantly from the other programme stars in their respective helium contents. The mean helium abundance for each cluster is close to the standard value, (He/H) 11:0.