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We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive [Formula omitted] meson muoproduction at COMPASS using 160 GeV/c polarised [Formula omitted] and [Formula omitted] beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0 GeV/ [Formula omitted] [Formula omitted] 17.0 GeV/ [Formula omitted], 1.0 (GeV/c) [Formula omitted] [Formula omitted] 10.0 (GeV/c) [Formula omitted] and 0.01 (GeV/c) [Formula omitted] [Formula omitted] 0.5 (GeV/c) [Formula omitted]. Here, W denotes the mass of the final hadronic system, [Formula omitted] the virtuality of the exchanged photon, and [Formula omitted] the transverse momentum of the [Formula omitted] meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons ( [Formula omitted]) indicate a violation of s-channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive [Formula omitted] production.

This article considers an antisurge protection method based on controlling the running speed of an ac electric motor driving a centrifugal compressor. The reasons for the occurrence and development of surge in centrifugal compressors are considered. Criteria for determining the presurge state of the system are proposed as well as actions to be taken for preventing a compressor accident in variable external conditions. It is proposed to avoid surge by slowing the motor down, that is, by switching to the underlying static head-capacity curve. A simulation model of a compressor with an appropriate control system has been developed. The properties of gases and the design features of the compressor are considered using the MATLAB Simulink modeling environment.

The article discusses the optimal layout of an autonomous vehicle traction system. In modern society, a special place is occupied by environmental issues. From year to year, a huge amount of statistics is published that reflect the scale of the damage that human products cause to the environment. Today, the main \"pest\" on the planet is surely cars with an internal combustion engine. At the same time, a complete rejection of motor transport, both in Russia and in the world, is impossible, because the life of modern man is inextricably linked with the constant movements, which are not always possible through urban electric transport. In recent years, many manufacturers of transport systems see the way out in autonomous electric transport systems development, which, in the future, will be able to replace vehicles with an internal combustion engine. In this article traction system variants, choice of electric motor optimal location, and also the control systems analysis which would correspond to requirements to the given technical process are considered.

— This paper examines how the gypsum-containing waste processing procedure influences the degree of rare-earth metal (REM) extraction from the waste. Gypsum-containing waste from the production of phosphoric acid was treated with aqueous solutions of various acids in the temperature range 25–140°C at solid : liquid ratios from 1 : 1 to 1 : 3. The results demonstrate that the largest REM extraction from phosphogypsum can be reached by treating with hydrochloric or nitric acid at the boiling point of the aqueous solution of the acid. Nitric acid is preferable because, after the acid treatment, the gypsum contains a large amount of nitrates, which can be used as agricultural fertilizers. Treatment of phosphogypsum at elevated temperatures and pressures leads to dissolution of a larger amount of gypsum, without increasing the REM yield. The highest economic efficiency of REM extraction from phosphogypsum is ensured by a solid : liquid ratio of about 1 ; 2, treatment temperature of 103–105°C, and cascade time no more than 10 min.

ECAL0 is a new electromagnetic calorimeter designed for studying generalized parton distributions at the COMPASS II experiment at CERN. It will be located next to the target and will cover larger photon angles (up to 30 degrees). It is a modular high-granularity Shashlyk device with total number of individual channels of approx. 1700 and readout based on wavelength shifting fibers and micropixel avalanche photodiodes. Characterization of the calorimeter includes tests of particular sub-components, tests of complete modules and module arrays, as well as a pilot run of a fully-functional, quarter-size prototype in the COMPASS experiment. The main goals of the tests on low-intensity electron beam at the ELSA accelerator in Bonn were: to provide energy calibration using electrons, to measure angular response of the calorimeter and to perform an energy scan to cross-check previously collected data. A dedicated measurement setup was prepared for the tests, including a 3x3 array of the ECAL0 modules, a scintillating-fibre hodoscope and a remotely-controlled motorized movable platform. The measurements were performed using three electron energies: 3.2 GeV, 1.6 GeV and 0.8 GeV. They include a calibration of the whole detector array with a straight beam and multiple angular scans.

Experimental results of the influence of technological parameters of phosphogypsum cascade leaching and evaporation of the solution obtained after the leaching on the rare earth elements (REE) content in it are presented. It was found that REE concentration in the solution grows almost linearly with increasing number of cascades [1]. Evaporation of REE - containing [2] solution down to 23 % of the initial volume leads to precipitation in which REE is about 0.5-0.6 % which coincides with the content of REE in the initial gypsum. This leads to purification of the solution from non - REE. At evaporation of the solution above 77 % an increased content of REE reaching 10-12 % was found in the precipitation. Thus, cascade leaching followed by solution evaporation is a cost-effective technological process. It allows obtaining a solution containing from several tens to few hundreds grams REE per liters with low content of Ca, P, S, Sr and other undesirable elements, which can be used for precipitation of REE carbonates or hydroxides [3].

Numerous papers deal with the closing lemma and variations thereof. The survey considers various types of closing lemmas. The ideas of proofs of the main results are presented, and schemes for constructing important examples are given. We illustrate the application of closing lemmas to the description of residual sets in spaces of dynamical systems.

Single hadron azimuthal asymmetries of positive and negative hadrons produced in muon semi-inclusive deep inelastic scattering off longitudinally polarised deuterons are determined using the 2006 COMPASS data and also combined all deuteron COMPASS data. For each hadron charge, the dependence of the azimuthal asymmetry on the hadron azimuthal angle ϕ is obtained by means of a five-parameter fitting function that besides a ϕ-independent term includes four modulations predicted by theory: sinϕ, sin2ϕ, sin3ϕ and cosϕ. The amplitudes of the five terms have been extracted, first, for the hadrons in the whole available kinematic region. In further fits, performed for hadrons from a restricted kinematic region, the ϕ-dependence is determined as a function of one of three variables (Bjorken-x, fractional energy of virtual photon taken by the outgoing hadron and hadron transverse momentum), while disregarding the others. Except the ϕ-independent term, all the modulation amplitudes are very small, and no clear kinematic dependence could be observed within experimental uncertainties.

The original version of this article unfortunately contained a mistake.

This volume is a tribute to one of the founders of modern theory of dynamical systems, the late Dmitry Victorovich Anosov.It contains both original papers and surveys, written by some distinguished experts in dynamics, which are related to important themes of Anosov's work, as well as broadly interpreted further crucial developments in the theory of dynamical systems that followed Anosov's original work.Also included is an article by A. Katok that presents Anosov's scientific biography and a picture of the early development of hyperbolicity theory in its various incarnations, complete and partial, uniform and nonuniform.