We present time-series uvby -β photometry of 41 classical Cepheid stars. A brief discussion of a comparison between the present data and previous photometric observations is included.

Descripción completa.

In this work, a dual illumination beam system is used to obtain the stress intensity factor in modes one (mode I) to mechanical elements during tension testing. The displacement field is obtained by means of electronic speckle pattern interferometry and…

We present echelle spectroscopy of the unresolved nuclei of the bipolar planetary nebulae M 2-9 and M 1-91. The spectrum is dominated by emission lines emitted under a wide range of physical conditions. From the observations we identify the emission…

We present speckle interferometric measurements of binary stars made during June of 2009 with the 1.5 m telescope of the Observatorio Astronómico Nacional at SPM (México). The data contain 189 position angle and separation measures of 144 systems. The measured…

New orbital parameters and masses for eight binaries were determined. Most of these were noted as being in need of correction due to large residuals to the previous best orbit. A modified Thiele-van den Bos method was used to obtain…

Line identifications are presented for the Hg-Mn Bp star HD 53244 (γCMa), in the spectral region λλ3750 - 6700 Å. This object is a member of the southern open cluster Cr 121. Comparison of the spectrum of HD 53244 with…

Descripción completa.

The cyclic model of a non-isothermal chemical engine operated between two reservoirs with different temperatures and chemical potentials is established, in which the irreversibilities resulting from the heat and mass transfer between the working fluid and the reservoirs are taken…

Ecological performance optimization of a generalized irreversible thermoacoustic heat engine with heat resistance, heat leakage, thermal relaxation and internal dissipation, in which heat transfer between the working fluid and heat reservoirs obeys a complex generalized heat transfer law Q