Improvement of Adhesion of the Wheels of the Railway Carriage to the Rails by Means of Supply of the Scale and Magnetite Particles to the Contact Zone

The article proposes a method to improve adhesion of the wheels to the rails of the railway carriage by means of supply of abrasive loose materials as an alternative to quartz sand to the zone of their contact: metal scale (Fe₃O₄ ) being the waste of rolling and forging, as well as the iron oxide—magnetite (FeO·Fe₂O₃) of the natural origin. The comparative assessment of efficiency of use of scale and magnetite was carried out in relation to quartz sand traditionally used for railway transport. The adhesion coefficient and wear intensity are used as comparison criteria

Providing stable friction properties of disc brakes for railway vehicles

A new approach is developed to ensure the stability of the coefficient of friction at different braking modes for the entire speed range of braking high-speed ground transport. The new approach is a combination of friction materials with individual effort effects on the brake disc. A brake pad design and its performance are confirmed experimentally

Phenomenological theory of phase transitions in highly piezoelectric perovskites

Recently discovered fine structure of the morphotropic phase boundaries in highly piezoelectric mixture compounds PZT, PMN-PT, and PZN-PT demonstrates the importance of highly non-linear interactions in these systems. We show that an adequate Landau-type description of the ferroelectric phase transitions in these compounds is achieved by the use of a twelfth-order expansion of the Landau potential in terms of the phenomenological order parameter. Group-theoretical and catastrophe-theory methods are used in constructing the appropriate Landau potential. A complete phase diagram is calculated in phenomenological parameter space. The theory describes both PZT and PZN-PT types of phase diagrams, including the newly found monoclinic and orthorhombic phases. Anomalously large piezoelectric coefficients are predicted in the vicinity of the phase transition lines.Comment: RevTex4, 8 pages, 2 figures. Dramatically changed after referees' Comments, to appear in Phys. Rev. B, 1 April 200

Superconducting states in the tetrahedral compound PrOs4Sb12

We find possible superconducting states for tetrahedral (Th) symmetry crystals with strong spin-orbit coupling using Landau theory. Additional symmetry breaking within the superconducting state is considered. We discuss nodes of the gap functions for the different states, secondary superconducting order parameters and coupling to the elastic strain. By comparing our results to experiments, we find that superconductivity in PrOs4Sb12 is best described by the three-dimensional representations of point group Th.Comment: 9 pages, 2 figures. Expanded version submitted to Physical Review

Discovery of an unusual bright eclipsing binary with the longest known period: TYC 2505-672-1 / MASTER OT J095310.04+335352.8

We report on the MASTER Global Robotic Net discovery of an eclipsing binary, MASTER OT J095310.04+335352.8, previously known as unremarkable star TYC 2505-672-1, which displays extreme orbital parameters. The orbital period P=69.1 yr is more than 2.5 times longer than that of epsilon-Aurigae, which is the previous record holder. The light curve is characterized by an extremely deep total eclipse with a depth of more than 4.5 mag, which is symmetrically shaped and has a total duration of 3.5 yrs. The eclipse is essentially gray. The spectra acquired with the Russian 6 m BTA telescope both at minimum and maximum light mainly correspond to an M0-1III--type red giant, but the spectra taken at the bottom of eclipse show small traces of a sufficiently hot source. The observed properties of this system can be better explained as the red giant eclipsed by a large cloud (the disk) of small particles surrounding the invisible secondary companion.Comment: 8 figures, 9 pages, Astronomy and astrophysics in prin

Photometric observations of the supernova 2009nr

We present the results of our UBVRI CCD photometry for the second brightest supernova of 2009, SN 2009nr, discovered during a sky survey with the telescopes of the MASTER robotic network. Its light and color curves and bolometric light curves have been constructed. The light-curve parameters and the maximum luminosity have been determined. SN 2009nr is shown to be similar in light-curve shape and maximum luminosity to SN 1991T, which is the prototype of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded far from the center of the spiral galaxy UGC 8255 and most likely belongs to its old halo population. We hypothesize that this explosion is a consequence of the merger of white dwarfs

Метод расчета статических характеристик асинхронного генератора с емкостным возбуждением

The paper analyzes the existing calculation methods for load characteristics of an asynchronous generator with a capacitive excitation. The improved calculation method for static characteristics of the  asynchronous generator working on a dynamic active-inductive load has been given in the paper. The methodology takes into account frequency of the generated voltage.Проведен анализ существующих методов расчета нагрузочных характеристик асинхронного генератора с емкостным возбуждением. Приведена уточненная методика расчета статических характеристик асинхронного генератора при работе на динамическую активно-индуктивную нагрузку с учетом изменения частоты генерированного напряжения

Optical polarization observations with the MASTER robotic net

We present results of optical polarization observations performed with the MASTER robotic net for three types of objects: gamma-ray bursts, supernovae, and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16$^m$). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.Comment: 31 pages, 12 figures, 4 tables; Exposure times in Table 2 have been correcte