Developing Effective Roll Cooling Systems Based on Computational Simulation

In order to retrofit a roll cooling system at the JSC ‘Katur Invest’ rolling mill, computational simulation was carried out for a process of accelerated emulsion spray cooling the rolls heated during rolling. Initial and boundary conditions for the Fourier equation in the case of a body of infinite length and arbitrary cross-sectional shape were determined for the thermal state conditions of rolls in mill stands No. 1, 2, 5, 7. After model adaptation, a comparative analysis of the roll temperature field dynamics in different cooling conditions was made based on experimental data. The analysis revealed that extending the time of emulsion cooling, evenwithout any further cooling process intensification, allows to significantly reduce both the maximum temperature level in a roll and its penetration depth, which results in required roll surface temperature reduction. Based on computational simulation, cooling parameters and conditions for the retrofitted cooling system are selected. Experimental data on roll surface temperature as measured before and after retrofitting the cooling system proved its effectiveness. Keywords: rolling, rolls, accelerated cooling, temperature field, simulatio

Synthesis and catalytic properties of copper(II) 1-aryl-5-benzothiazolylformazanates

New copper(II) benzothiazolylformazane complexes were synthesized and immobilized on AN-18 anion exchanger. The influence of the composition of the coordination core of copper(II) benzthiazolylformazanates and temperature on their catalytic properties in decomposition of H2O2 and oxidation of Na2S in aqueous solution was studied

Synthesis and spectroscopic features of iron(II) 1-aryl-5-benzothiazol-2- ylformazanates

New iron(II) coordination compounds with 1-aryl-5-(benzothiazol-2-yl) formazans were prepared. Their compositions and structures were determined by electronic spectroscopy, mass spectrometry, single crystal X-ray diffraction analysis, and magnetochemical measurements. © 2008 Pleiades Publishing, Ltd.Russian Foundation for Basic Researc

Developing a modern thermal strengthening technique for regulated fishplate cooling

A modern ecologically friendly technique for fishplate (joint bar) thermal strengthening by regulated water cooling is proposed. The proposed technique can successfully replace the conventional one - oil quenching - due to making the cooling process more controlled by obtaining a uniform temperature distribution over fishplate elements with a different mass such as heads and the wet. The oil quenching process is an out of control fire hazardous one and requires controlling the permanent cooling capability, fishplate flushing after the operation. It is necessary to utilize the oil and to have a special ventilation system. As a mineral oil substitute, the usage of polymer media has been investigated. Within the time, the polymer solution needs to be recycled; the high cost of polymer concentrates also plays an important role. Quenching by water spraying is the most ecological and controlled type of thermal strengthening. The technique was validated by a test bench experiment and implemented in the metallurgical industry. The mechanical properties have been obtained to meet the GOST 4133-73 technical requirements. Moreover, the analysis made showed that when the controlled cooling device is fitted into the line existing due to exclusion of the hardening tank and washing machine from the processing flow it is possible to save energy, exclude the expenditures for acquisition, the preparation of oil and washing mixtures as well as for regeneration of the oils used and washing solutions. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Wave Excitation in Disks Around Rotating Magnetic Stars

The accretion disk around a rotating magnetic star (neutron star, white dwarf or T Tauri star) is subjected to periodic vertical magnetic forces from the star, with the forcing frequency equal to the stellar spin frequency or twice the spin frequency. This gives rise bending waves in the disk that may influence the variabilities of the system. We study the excitation, propagation and dissipation of these waves using a hydrodynamical model coupled with a generic model description of the magnetic forces. The $m=1$ bending waves are excited at the Lindblad/vertical resonance, and propagate either to larger radii or inward toward the corotation resonance where dissipation takes place. While the resonant torque is negligible compared to the accretion torque, the wave nevertheless may reach appreciable amplitude and can cause or modulate flux variabilities from the system. We discuss applications of our result to the observed quasi-periodic oscillations from various systems, in particular neutron star low-mass X-ray binaries.Comment: Small changes/clarifications. To be published in ApJ, Aug.20,2008 issu

Three-dimensional Simulations of Disk Accretion to an Inclined Dipole: I. Magnetospheric Flow at Different Theta

We present results of fully three-dimensional MHD simulations of disk accretion to a rotating magnetized star with its dipole moment inclined at an angle Theta to the rotation axis of the disk. We observed that matter accretes from the disk to a star in two or several streams depending on Theta. Streams may precess around the star at small Theta. The inner regions of the disk are warped. The warping is due to the tendency of matter to co-rotate with inclined magnetosphere. The accreting matter brings positive angular momentum to the (slowly rotating) star tending to spin it up. The corresponding torque N_z depends only weakly on Theta. The angular momentum flux to the star is transported predominantly by the magnetic field; the matter component contributes < 1 % of the total flux. Results of simulations are important for understanding the nature of classical T Tauri stars, cataclysmic variables, and X-ray pulsars.Comment: 26 pages, 22 figures, LaTeX, macros: emulapj.sty, avi simulations are available at http://www.astro.cornell.edu/us-rus/inclined.ht

The Discovery of an Anomalous X-ray Pulsar in the Supernova Remnant Kes 73

We report the discovery of pulsed X-ray emission from the compact source 1E 1841-045, using data obtained with the Advanced Satellite for Cosmology and Astrophysics. The X-ray source is located in the center of the small-diameter supernova remnant (SNR) Kes 73 and is very likely to be the compact stellar-remnant of the supernova which formed Kes 73. The X-rays are pulsed with a period of ~ 11.8 s, and a sinusoidal modulation of roughly 30 %. We interpret this modulation to be the rotation period of an embedded neutron star, and as such would be the longest spin period for an isolated neutron star to-date. This is especially remarkable since the surrounding SNR is very young, at ~ 2000 yr old. We suggest that the observed characteristics of this object are best understood within the framework of a neutron star with an enormous dipolar magnetic field, B ~ 8x10^14 G

Magnetic fileds of coalescing neutron stars and the luminosity function of short gamma-ray burst

Coalescing neutron star binaries are believed to be the most reliable sources for ground-based detectors of gravitational waves and likely progenitors of short gamma-ray bursts. In the process of coalescence, magnetic fields of neutron stars can induce interesting observational manifestations and affect the form of gravitational wave signal. In this papaer we use the population synthesis method to model the expected distribution of neutron star magnetic fields during the coalescence under different assumptions on the initial parameters of neutron stars and their magnetic field evolution. We discuss possible elecotrmagnetic phenomena preceding the coalescence of magnetized neutron star binaries and the effect of magnetic field on the gravitational wave signal. We find that a log-normal (Gaussian in logarithms) distribution of the initial magnetic fields of neutron stars, which agrees with observed properties of radio pulsars, produces the distribution of the magnetic field energy during the coalescence that adequately describes the observed luminosity function of short gamma-ray bursts under different assumptions on the field evolution and initial parameters of neutron stars. This agreement lends further support to the model of coalescing neutron star binaries as progenitors of gamma-ray bursts.Comment: v.2, LATEX, 25 pages, inc. 7 ps figures, Astron. Lett., in press. Typos corrected, reference adde

Magnetically Driven Warping, Precession and Resonances in Accretion Disks

The inner region of the accretion disk onto a rotating magnetized central star (neutron star, white dwarf or T Tauri star) is subjected to magnetic torques which induce warping and precession of the disk. The origin of these torques lies in the interaction between the (induced) surface current on the disk and the horizontal magnetic field (parallel to the disk) produced by the inclined magnetic dipole. Under quite general conditions, there exists a magnetic warping instability in which the magnetic torque drives the disk plane away from the equatorial plane of the star toward a state where the disk normal vector is perpendicular to the spin axis. Viscous stress tends to suppress the warping instability at large radii, but the magnetic torque always dominates as the disk approaches the magnetosphere boundary. The magnetic torque also drives the tilted inner disk into retrograde precession around the stellar spin axis. Moreover, resonant magnetic forcing on the disk can occur which may affect the dynamics of the disk. The magnetically driven warping instability and precession may be related to a number observational puzzles, including: (1) Spin evolution (torque reversal) of accreting X-ray pulsars; (2) Quasi-periodic oscillations in low-mass X-ray binaries; (3) Super-orbital periods in X-ray binaries; (4) Photometric period variations of T Tauri stars.Comment: 39 pages including 1 ps figure; Published version; ApJ, 524, 1030-1047 (1999