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.

The helium-weak silicon star HR 7224. I. Radial velocity and line profile variations

Abstract: Aims. HR 7224 is a rapidly rotating He-weak silicon star known as photometrically variable with a period of 1.123 d. Drastic changes of photometric amplitude and period were reported in 2003. We investigate the star spectroscopically to determine the time scales of variability, to derive basic atmospheric parameters, and to give first estimates on possible surface structures. Methods. We investigate time series of more then 570 high-resolution spectra of HR 7224 for radial velocity and line profile variations. The rotation period is determined from period analysis of data. Comparing radial velocity and line profile variations we draw first conclusions on possible surface structures in terms of line strengths. From Balmer and metal lines we determine Teff ,l ogg, v sini ,a nd metal abundances depending on rotation phase. Results. The star shows a remarkable amplitude of radial velocity variation of ± 6k m s −1 . From this variation we deduce a rotation period of 1.12324 d. The period and the double-wave shaped radial velocity curve are in agreement with earlier photometric findings. The observed radial velocity variations can be explained by the rotation period and its harmonics and no further periodic contributions were found in the residuals. HR 7224 has enhanced Si and Fe abundances whereas He is extremely depleted. The star shows line strength variations of all observed elements with the rotation period. Variations of radial velocity, line strength and line shape of silicon lines and their relationships can be explained by assuming two large spots on the stellar surface showing enhanced line strength. From Balmer lines we deduce different temperatures of the star for different rotation phases. The observed difference in amplitudes of the variation of Mg ii and Si ii lines supports the assumption of surface regions of different temperature on this presumably magnetic Cp star. Synthetic uvby colors computed from adapted synthetic spectra confirm the high photometric amplitude reported for the 2003 light curves.

Recria de bovinos nelore em pastos de Brachiaria brizantha com suplementação protéica ou com acesso a banco de proteína de Leucaena lecocephala: desempenho animal

Abstract: The performance of 192 weaned Nelore steers grazing on Brachiaria brizantha pastures(Teste), or supplemented during the dry season (Seca), all year around (Ano) or with free access to a leucaena bank (Banco), was evaluated in a random block design with four replications. The dry season supplement had 46.9% CP, 70% rumen degradable, and the wet season supplement, 43.9% CP, 60% degradable. During the dry season, the animals of Ano and Seca showed higher gains than Banco and Teste (.534 and .486 vs .277 and .201 kg/day, respectively). In the wet season animals on Ano and Bank had higher gains than Seca and Teste (.782 and .741 vs .584 and .645 kg/day). The live weight gain per unit of area showed the same behavior of daily gain. Supplements with escape protein or access to a leucaena bank during the wet season showed an efficient alternative.

Effects of solar irradiation on thermally driven CO2 methanation using Ni/CeO2–based catalyst

Abstract: Utilization of the renewable energy sources is one of the main challenges in the state-of-the-art technologies for CO2 recycling. Here we have taken advantage of the solar light harvesting in the thermocatalytic approach to carbon dioxide methanation. The large-surface-area Ni/CeO2 catalyst produced by a scalable low-cost method was characterized and tested in the dark and under solar light irradiation conditions. Light-assisted CO2 conversion experiments as well as in-situ DRIFT spectrometry, performed at different illumination intensities, have revealed a dual effect of the incident photons on the catalytic properties of the two-component Ni/CeO2 catalyst. On the one hand, absorbed photons induce a localized surface plasmon resonance in the Ni nanoparticles followed by dissipation of the heat to the oxide matrix. On the other hand, the illumination activates the photocatalytic properties of the CeO2 support, which leads to an increase in the concentration of the intermediates being precursor for methane production. Analysis of the methane production at different temperatures and illumination conditions has shown that the methanation reaction in our case is controlled by a photothermally-activated process. The used approach has allowed us to increase the reaction rate up to 2.4 times and consequently to decrease the power consumption by 20 % under solar illumination, thus replacing the conventional thermal activation of the reaction with a green energy source.

Sleptsov Nets Run Fast

Abstract: We show that Sleptsov place–transition nets (that allow transition firing in multiple instances at a step) run fast by implementing multiplication and division operations in polynomial time. In comparison, Petri nets (PNs) implement the mentioned operations in exponential time. Moreover, PNs are obtained as a special case of Sleptsov nets (SNs) using loops with places having unit marking attached to each transition. In addition, we develop basics of an SN programming technology including basic operations and program composition rules. We provide examples of programs written in SN language for encryption/decryption with the RSA algorithm, calculation of fuzzy logic functions, and parallel calculation of the solutions to Laplace equations. SN computers promise hyper-performance because of a concurrent programming style consisting of a concise graphical language and small granulation of parallel processes on the level of separate events.

Experimental and Computer Researches of Ferroconcrete Floor Slabs at High-Temperature Influences

Abstract: The paper presents experimental and computer researches of ferroconcrete beams at high-temperature influences. There were conducted the experimental fire tests of ferroconcrete beams. The most promising way of verifying these experimental research data is computer simulation of structures, also during a fire. In order to evaluate the quality of the experiment and the reliability of the received temperature distribution, there was conducted a computer simulation of the ferroconcrete beam in the ANSYS R.17.1 software complex. There were conducted a comparative analysis of the results of experimental studies and numerical analysis. The results confirm that the method of conducted experimental research and computer simulation with further numerical analysis can be recommended for practical application.