97 research outputs found

    Design of Drum Type Apparatus for Processing of Bulk Materials

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    The article presents the development and research of drum continuous mixers, most attention is paid to the results of theoretical (using of cybernetic approach) and experimental studies of longitudinal mixing particulate material in rotating drums of continuous action, the influence of internal recycles of material flows, intensifying the process of smoothing the input fluctuations. The authors analyzed the influence of internal recycles material flows, intensifying the process of smoothing the input fluctuations. The results presented in this paper were obtained by the experiments on the smoothing ability determination during which they change the frequency of the drum rotation, the location of the Г-shaped mixer blades on the drum mixer. The article reported that the studies were conducted on three mixtures which components have different physical and mechanical systems with various dispersed liquid additives and without it

    Relativistic quantum model of confinement and the current quark masses

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    We consider a relativistic quantum model of confined massive spinning quarks and antiquarks which describes leading Regge trajectories of mesons. The quarks are described by the Dirac equations and the gluon contribution is approximated by the Nambu-Goto straight-line string. The string tension and the current quark masses are the main parameters of the model. Additional parameters are phenomenological constants which approximate nonstring short-range contributions. Comparison of the measured meson masses with the model predictions allows one to determine the current quark masses (in MeV) to be ms=227±5, mc=1440±10, mb=4715±20m_s = 227 \pm 5,~ m_c = 1440 \pm 10,~ m_b = 4715 \pm 20. The chiral SU3SU_3 model[23] makes it possible to estimate from here the uu- and dd-quark masses to be mu=6.2±0.2m_u = 6.2 \pm 0.2~ Mev and md=11.1±0.4m_d = 11.1 \pm 0.4 Mev.Comment: 15 pages, LATEX, 2 tables. (submitted to Phys.Rev.D

    Experimental and theoretical study of swept-wing boundary-layer instabilities. Three-dimensional Tollmien-Schlichting instability

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    Extensive combined experimental and theoretical investigations of the linear evolution of three-dimensional (3D) Tollmien-Schlichting (TS) instability modes of 3D boundary layers developing on a swept airfoil section have been carried out. The flow under consideration is the boundary layer over an airfoil at 35 degrees sweep and an angle of attack of +1.5 degree. At these conditions, TS instability is found to be the predominant one. Perturbations with different frequencies and spanwise wavenumbers are generated in a controlled way using a row of elastic membranes. All experimental results are deeply processed and compared with results of calculations based on theoretical approaches. Very good quantitative agreement of all measured and calculated stability characteristics of swept-wing boundary layers is achieved

    Verification and characterization of predominant instabilities of swept-wing boundary layers

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    The problem of identification and verification of the most important linear stability mechanisms of initial stages of laminar-turbulent transition in three-dimensional (3D) swept-wing boundary layers is discussed based on experimental and theoretical investigations performed, in particular, for real swept airfoil sections. Detailed analysis of all main boundary-layer stability characteristics with respect to the cross-flow (CF) instability modes and 3D Tollmien-Schlichting (TS) instability modes is carried out based on experimental data, as well as on computations within the framework of linear stability theories and the Parabolized Stability Equation (PSE) approach. The possibility of a very good agreement between all main measured and calculated stability characteristics is shown. Role of surface curvature and base-flow non-parallelism is discussed

    Experimental and theoretical study of swept-wing boundary-layer instabilities: Unsteady crossflow instability

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    Extensive combined experimental and theoretical investigations of the linear evolution of unsteady (in general) Cross-Flow (CF) and threedimensional (3D) Tollmien-Schlichting (TS) instability modes of 3D boundary layers developing on a swept airfoil section have been carried out. CF-instability characteristics are investigated in detail at an angle of attack of −5○ when this kind of instability dominates in the laminarturbulent transition process, while the 3D TS-instability characteristics are studied at an angle of attack of +1.5○ when this kind of instability is predominant in the transition process. All experimental results are deeply processed and compared with results of calculations based on several theoretical approaches. For the first time, very good quantitative agreement of all measured and calculated stability characteristics of swept-wing boundary layers is achieved both for unsteady CF- and 3D TS-instability modes for the case of a boundary layer developing on a real swept airfoil. The first part of the present study (this paper) is devoted to the description of the case of CF-dominated transition, while the TS-dominated case will be described in detail in a subsequent second part of this investigation

    Quantitative study of localized mechanisms of excitation of cross-flow instability modes in a swept-wing boundary layer

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    An experimental study of two efficient receptivity mechanisms of excitation of cross-flow (CF) instability modes is carried out in a boundary layer of a real airfoil section of a swept wing due to: (i) action of localized surface vibrations, and (ii) scattering of 2D freestream vortices on them. It is found that the two mechanisms lead to rather efficient excitation of CF-modes both at surface vibration frequency and at combination 'vortex-vibration' frequencies. First estimations of the corresponding localized receptivity coefficients are obtained. Direct comparison of the experimental amplification curves of the excited CF-modes with those calculated based on the linear stability theory (LST) has shown that the experimental data obtained at vibration frequency are in excellent agreement with the LST. At the same time, growth rates of the CF-modes excited at combination frequencies are found to be completely inconsistent with the LST. A possible explanation of this phenomenon via action of a new efficient distributed receptivity mechanism is suggested. This mechanism is associated with scattering of freestream vortices on rather high-amplitude CF-modes excited by surface vibrations

    Substantial fat mass loss reduces low-grade inflammation and induces positive alteration in cardiometabolic factors in normal-weight individuals

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    ( )The accumulation of fat, especially in visceral sites, is a significant risk factor for several chronic diseases with altered cardiometabolic homeostasis. We studied how intensive long-term weight loss and subsequent weight regain affect physiological changes, by longitudinally interrogating the lipid metabolism and white blood cell transcriptomic markers in healthy, normal-weight individuals. The current study examined 42 healthy, young (age: 27.5 +/- 4.0 years), normal-weight (body mass index, BMI: 23.4 +/- 1.7 kg/m(2)) female athletes, of which 25 belong to the weight loss and regain group (diet group), and 17 to the control group. Participants were evaluated, and fasting blood samples were drawn at three time points: at baseline (PRE); at the end of the weight loss period (MID: 21.1 +/- 3.1 weeks after PRE); and at the end of the weight regain period (POST: 18.4 +/- 2.9 weeks after MID). Following the weight loss period, the diet group experienced a similar to 73% reduction (similar to 0.69 kg) in visceral fat mass (false discovery rate, FDR <2.0 x 10(-16)), accompanied by anti-atherogenic effects on transcriptomic markers, decreased low-grade inflammation (e.g., as alpha(1)-acid glycoprotein (FDR = 3.08 x 10(-13)) and hs-CRP (FDR = 2.44 x 10(-3))), and an increase in functionally important anti-atherogenic high-density lipoprotein -associated metabolites (FDR <0.05). This occurred even though these values were already at favorable levels in these participants, who follow a fitness-lifestyle compared to age- and BMI-matched females from the general population (n = 58). Following the weight regain period, most of the observed beneficial changes in visceral fat mass, and meta bolomic and transcriptomic profiles dissipated. Overall, the beneficial anti-atherogenic effects of weight loss can be observed even in previously healthy, normal-weight individuals.Peer reviewe

    Heuristic Models of Two-Fermion Relativistic Systems with Field-Type Interaction

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    We use the chain of simple heuristic expedients to obtain perturbative and exactly solvable relativistic spectra for a family of two-fermionic bound systems with Coulomb-like interaction. In the case of electromagnetic interaction the spectrum coincides up to the second order in a coupling constant with that following from the quantum electrodynamics. Discrepancy occurs only for S-states which is the well-known difficulty in the bound-state problem. The confinement interaction is considered too. PACS number(s): 03.65.Pm, 03.65.Ge, 12.39.PnComment: 16 pages, LaTeX 2.0

    New superstructural thermoplastics and carbon composite materials based on them

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    New superconstructional polyarylates with glass transition temperatures from 216 to 280°C and polyethersulfones with glass transition temperatures from 230 to 255°C have been developed. On the basis of these polymers, industrial polysulfone PSFF-30, PSF-150, polyethersulfone E-3010, polyetherimide Ultem 1000, PEEK and PEKK, and two types of carbon fabrics, thermoplastic prepregs and consolidated carbon composite plates were obtained, and their mechanical properties under compression and three-point bending were determined

    Probing Anomalous Quartic Couplings in e-gamma and gamma-gamma Colliders

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    We analyze the potential of the e+e- Linear Colliders, operating in the e-gamma and gamma-gamma modes, to probe anomalous quartic vector--boson interactions through the multiple production of W's and Z's. We examine all SU(2)LU(1)YSU(2)_L \otimes U(1)_Y chiral operators of order p^4 that lead to new four--gauge--boson interactions but do not alter trilinear vertices. We show that the e-gamma and gamma-gamma modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10^{-2} at 90% CL. Moreover, the information gathered in the e-gamma mode can be used to reduced the ambiguities of the e+e- mode.Comment: Revtex, 18 pages, 6 figure
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