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 detection of the rich p-mode spectrum and asteroseismology of Przybylski's star

Abstract: Aims. We investigate the oscillation spectrum of the most chemically-peculiar star in the sky, the rapidly-oscillating magnetic (roAp) star HD 101065. Methods. High-precision radial velocity (RV) measurements, spanning four consecutive nights on 3–6 March, 2004, were obtained with the HARPS echelle-spectrometer at the ESO 3.6-m telescope, and photometric data were acquired during 6 nights of observations at the 24-inch telescope of Siding Spring Observatory. The RVs were measured using all spectral lines in the wavelength range 4400–5100 A. Results. We detected a rich spectrum of oscillation modes with semi-amplitudes ranging between 217 m s −1 and 1.6 m s −1 .T hese belong to the complete spectrum of high-order, low � = 0–2 modes, having a large spacing of Δν = 64.07 ± 0.9 μHz. We calculated the nonadiabatic frequencies of axisymmetric high-order p-modes for main-sequence models with dipole magnetic fields of two chemical compositions (X,Z) = (0.7, 0.02) and (X,Z) = (0.695, 0.025). The former composition provided the best fit model and yielded stellar parameters of mass, M = 1.525 ± 0.025 M� ,a ge= (1.5 ± 0.1) × 10 9 yr, effective temperature log Te = 3.821 ± 0.006, luminosity logL/L� = 0.797 ± 0.026, surface gravity log g = 4.06 ± 0.04, and polar magnetic field strength, Bp = 8.7 ± 0. 3k G. We are able to identify the modes of all detected oscillation frequencies. The photometric U and B light curves have maxima that precede the RV maximum by 0.16–0.19 in phase.

An experimental investigation and modelling of the thermodynamic properties of isobutane–compressor oil solutions: Some aspects of experimental methodology

Abstract: This paper presents experimental data for the solubility, density and capillary constant for solutions of natural refrigerant isobutane with commercial mineral compressor oil Azmol over a wide range of temperatures and concentrations. Based on information for the capillary constant, the surface tension of the solutions isobutane/Azmol is determined. The experimental data were obtained in the temperature range from 303 K to 363 K and at pressures up to 1.7 MPa using static methods. The experimental data obtained for the solutions of the natural refrigerant isobutane with the commercial mineral compressor oil Azmol are sufficiently described with the help of correlations based on the theory of thermodynamic similarity. The paper reports variation of the vapor pressure, density, capillary constant and surface tension as a function of concentration for the isobutane/Azmol solutions. The enthalpy of liquid phase of the isobutane/Azmol solutions is calculated. The analysis of the behaviour of the excess thermodynamic functions is carried out. The paper examines experimental and methodical uncertainties in the investigation of thermodynamic properties of the refrigerant/oil solutions (ROS). The influence of the time taken to establish thermodynamic equilibrium in the experimental cell on the uncertainty of the experimental data for gas-saturated mixtures such as ROS is discussed. Information about the changing concentration of refrigerant in the liquid phase of the ROS and in the surface layer of the liquid phase of the ROS at increasing temperature is presented. In addition, the experimental data for the density, surface tension and refractive index of the mineral compressor oil Azmol are reported.

Automatic load seeking control for a multitorque motor

Abstract: Method and apparatus for matching the power output of a multitorque motor with the torque requirement of a connected load device. The stator windings of the motor are automatically connected in various different configurations to provide the optimum motor torque demanded by a connected load device which imposes varying load conditions on the motor. A novel control circuitry is connected between the motor starter and the motor stators. The control measures the power drawn by the motor stators and selects the most optimum configuration thereof which meets the changing torque requirements of the connected load device. This selection of optimum stator winding configurations commensurate with torque demand operates the motor in the lowest possible torque mode, which is considered the best electrical and mechanical operation of the motor and connected load device.