The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection ...into the halo from past activity in the nucleus of the Milky Way
; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova
but part of a vast Galaxy-scale structure closely related to features seen in γ-rays
. Large energy injections from the Galactic centre
are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 10
erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.
In recent years, there is an increased interest in pipes with regularly variable section area (converging-diverging pipes) in the oil chemical industry. At the same time, there is no simple ...engineering technique for calculation of hydrodynamic characteristics of such devices, which significantly impedes computations for mass exchange processes inside them. Attempts to concentrate energy dissipation and their control near the phase boundary were mainly directed at using the fluid flow pulses induced by an external generator, alternating displacement field, pulses caused by fluid flow through the conduit with a variable cross-section. As a result, it has been revealed that the forces determined by action of convective acceleration are capable of causing a significant deformation and breakage of disperse inclusions (drops and bubbles). For rigid particles, the action of the convective acceleration leads to a periodic impulse renewal of liquid near the surface of the rigid particle.
Impulse non-stationary flooding requires managing the processes influencing reliability and durability of the tubing string. In this case, it is necessary to determine the medium displacement for ...known dimensional parameters and stress fields, while taking into account the dynamic solution for the low-frequency limit. The results obtained from the analysis are compared against the measurements performed by various authors. Assuming there is a certain frequency of injected fluid oscillation or pressure pulses, one could expect that the radial movement is in equilibrium with the pressure existing at any given period of time. As a result, expressions describing the behavior of impulse waves propagating along the pipe wall were obtained. The reflected waves appear in all cases: whether the change in speed is caused by a change in the pipe wall thickness, Young modulus or shear rigidity of the environment. Changes in density or bulk modulus of the injected fluid or in the radius of the wellbore also cause reflected waves; all the waves may be described by a single equation.
This is the first paper in a series of studies of the Coma cluster using the SRG/eROSITA X-ray data obtained in the course of the calibration and performance verification observations. The data cover ...a ~3° × 3° area around the cluster with a typical exposure time of more than 20 ks. The stability of the instrumental background and operation of the SRG observatory in the scanning mode provided us with an excellent data set for studies of the diffuse emission up to a distance of ~1.5
R
200
from the Coma center. In this study, we discuss the rich morphology revealed by the X-ray observations (also in combination with the SZ data) and argue that the most salient features can be naturally explained by a recent (ongoing) merger with the NGC 4839 group. In particular, we identify a faint X-ray bridge connecting the group with the cluster, which is convincing proof that NGC 4839 has already crossed the main cluster. The gas in the Coma core went through two shocks, first through the shock driven by NGC 4839 during its first passage through the cluster some gigayear ago and, more recently, through the “mini-accretion shock” associated with the gas settling back to quasi-hydrostatic equilibrium in the core. After passing through the primary shock, the gas should spend much of the time in a rarefaction region, where radiative losses of electrons are small, until the gas is compressed again by the mini-accretion shock. Unlike “runway” merger shocks, the mini-accretion shock does not feature a rarefaction region downstream and, therefore, the radio emission can survive longer. Such a two-stage process might explain the formation of the radio halo in the Coma cluster.
Emergencies and breaks of field pipelines result in both gas, oil, and refined products waste and high costs for maintenance and repair evaluated in billiard rubles annually. The purpose of this work ...is calculate test pressure in field pipelines with the account of pipes ovality and curvature, stress pattern, surface damage areas, plasticity of pipe steels and optimal parameters control. To determine maximum test pressure it is advisable to divide the pipeline into parts for hydraulic tests, denote sources of water feeding and points of water discharge. Minimum elastic bend radius (EBR) and walls thickness (WT) should be found for every part. Unfailing service can be provided by periodical hydraulic tests, e.g. once in three years (in case when the test pressure is σtp = σfp) or by periodic decrease of the operational pressure. The other way to provide unfailing service of the pipeline is decreasing cyclic load.
The international accelerator neutrino experiment T2K (Tokai-to-Kamioka) began accumulating data in 2010 and has since then accomplished 10 runs in the neutrino and antineutrino modes. The present ...article reports on the latest results following from the analysis of these data and including the first ever 3
constraints on the
CP
-violating phase
. Also, the plans for an upgrade of the near detector ND280 are surveyed.
Abstract
It should be noted that numerous theoretical studies on flow hydromechanics in the centrifugal field have not been sufficiently used in designing separators with a high productivity index. ...This is caused by the extreme complexity of the flow conditions of the separated liquid in the intrarotor space. Therefore, experimental studies of intra-rotor flows have now gained great importance. The obtained results of studies carried out on a real product at a pressure and flow rate corresponding to production conditions made it possible to create and manufacture an industrial sample of the assembly. The authors use experimental data to calculate similar hydrocyclones ment for operation with other mixtures.
This paper analyzes stress-strain behavior and bearing capacity of a rotor in a self-discharging separator, diameter 500 mm, manufactured from parts that underwent a hardening cycle. Three variants ...of the rotor were studied having the same design but differing in body materials: austenitic steels 06X17H13M3-BД, ALIII-23-43-02 and austenitic-ferritic steel 10X26H5M, ALIII-23-24. Research results allow recommending austenitic-ferritic steel for manufacture of separator rotors, as they provide necessary margin of safety for the design.
Abstract
The total rock pressure on a formation wing is greater than the lateral pressure, and on the fold, on the contrary, the lateral rock pressure is greater than the total pressure. As a result, ...the formation material flows from wing zones to the fold, as a result of which the formation thickness on the fold increases, as noted by the studies of Soviet scientists. The study of the mechanism of hydraulic fracturing during water injection revealed large fracturing pressures in wells located in reduced parts of the structure (fold wings), and smaller pressures – in elevated parts (fold). The study showed that if the rock of the well bore zone is destabilized during field development for well operation, fresh water causes hydration and swelling or dispersion of clays, which act as the rock cementing material. This can both lead to a decrease in permeability and to the destruction of the well bore zone. This effect during well development may be prevented by using mineralized reservoir water or fresh water with hydration inhibitor additives such as NaCl (5-10%), CaCl
2
(1-3%), KC1 (1-3%). Another complication in well completion is the colmatation of the well bore zone. In order to ensure the stability of the fixed part of the formation behind tubing in the bottomhole zone, there is a need to ensure the static equilibrium in the porous medium. Rocks with low rheological properties (low relaxation rate) provide longer resistance of the well bore zone to destruction.
SRG X-ray orbital observatory Sunyaev, R.; Arefiev, V.; Babyshkin, V. ...
Astronomy and astrophysics (Berlin),
12/2021, Letnik:
656
Journal Article
Recenzirano
Odprti dostop
The orbital observatory Spectrum-Roentgen-Gamma (SRG), equipped with the grazing-incidence X-ray telescopes Mikhail Pavlinsky ART-XC and eROSITA, was launched by Roscosmos to the Lagrange L2 point of ...the Sun–Earth system on July 13, 2019. The launch was carried out from the Baikonur Cosmodrome by a Proton-M rocket with a DM-03 upper stage. The German telescope eROSITA was installed on SRG under an agreement between Roskosmos and the DLR, the German Aerospace Agency. In December 2019, SRG started to perform its main scientific task: scanning the celestial sphere to obtain X-ray maps of the entire sky in several energy ranges (from 0.2 to 8 keV with eROSITA, and from 4 to 30 keV with ART-XC). By mid-June 2021, the third six-month all-sky survey had been completed. Over a period of four years, it is planned to obtain eight independent maps of the entire sky in each of the energy ranges. The sum of these maps will provide high sensitivity and reveal more than three million quasars and over one hundred thousand massive galaxy clusters and galaxy groups. The availability of eight sky maps will enable monitoring of long-term variability (every six months) of a huge number of extragalactic and Galactic X-ray sources, including hundreds of thousands of stars with hot coronae. In addition, the rotation of the satellite around the axis directed toward the Sun with a period of four hours enables tracking the faster variability of bright X-ray sources during one day every half year. The chosen strategy of scanning the sky leads to the formation of deep survey zones near both ecliptic poles. The paper presents sky maps obtained by the telescopes on board SRG during the first survey of the entire sky and a number of results of deep observations performed during the flight to the L2 point in the frame of the performance verification program, demonstrating the capabilities of the observatory in imaging, spectroscopy, and timing of X-ray sources. It is planned that in December 2023, the observatory will for at least two years switch to observations of the most interesting sources in the sky in triaxial orientation mode and deep scanning of selected celestial fields with an area of up to 150 square degrees. These modes of operation were tested during the performance verification phase. Every day, data from the SRG observatory are dumped onto the largest antennas of the Russian Deep Space Network in Bear Lakes and near Ussuriysk.
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