We study the distribution of cold dark matter (CDM) in cosmological simulations from the FIRE (Feedback In Realistic Environments) project, for M
* ∼ 104–11 M⊙ galaxies in M
h ∼ 109–12 M⊙ haloes. ...FIRE incorporates explicit stellar feedback in the multiphase interstellar medium, with energetics from stellar population models. We find that stellar feedback, without ‘fine-tuned’ parameters, greatly alleviates small-scale problems in CDM. Feedback causes bursts of star formation and outflows, altering the DM distribution. As a result, the inner slope of the DM halo profile (α) shows a strong mass dependence: profiles are shallow at M
h ∼ 1010–1011 M⊙ and steepen at higher/lower masses. The resulting core sizes and slopes are consistent with observations. This is broadly consistent with previous work using simpler feedback schemes, but we find steeper mass dependence of α, and relatively late growth of cores. Because the star formation efficiency M
*/M
h is strongly halo mass dependent, a rapid change in α occurs around M
h ∼ 1010 M⊙ (M
* ∼ 106–107 M⊙), as sufficient feedback energy becomes available to perturb the DM. Large cores are not established during the period of rapid growth of haloes because of ongoing DM mass accumulation. Instead, cores require several bursts of star formation after the rapid build-up has completed. Stellar feedback dramatically reduces circular velocities in the inner kpc of massive dwarfs; this could be sufficient to explain the ‘Too Big To Fail’ problem without invoking non-standard DM. Finally, feedback and baryonic contraction in Milky Way-mass haloes produce DM profiles slightly shallower than the Navarro–Frenk–White profile, consistent with the normalization of the observed Tully–Fisher relation.
As demonstrated earlier, the mode-coupling approach taking into account the interaction between shear dynamic modes and soft density fluctuations gives the expression for shear viscosity in good ...agreement with the viscosity of various liquids at low temperatures. The corresponding relations for shear and bulk viscosities of a hard-sphere fluid are more careful studied in this work. The hard-sphere fluid is the simplest nontrivial example of the system having liquid-solid transition. It can be studied by molecular dynamics allowing accurate calculations of all the necessary parameters. It is demonstrated that the mode-coupling expressions for viscosities agree well with the simulation results.
In this article new approaches of determining vibration intensity of vibration compactors and molding machines by two examples: for the simplest type of vibros and for vibrating areas with modulated ...multipara meter vibrations with the purpose assessing the technical and economic efficiency of parameters of new technologies regimes, as well as assessing practical feasibility of optimal values of constructive and technological parameters of proposed technologies in the production of combined constructions of ameliorative objects are described. In the same concrete mix, high-frequency oscillations damp more strongly than low-frequency oscillations. With increasing mobility and the degree of compaction of the mixture, the attenuation becomes lower, and the propagation velocity of the oscillations to the limit corresponding to the maximum for these conditions of compaction. By stabilizing the amplitude, intensity of the oscillations, the speed of their propagation, and the wavelength, one can judge the end of compaction of the mixture.
In a superconductor that lacks inversion symmetry, the spatial part of the Cooper pair wave function has a reduced symmetry, allowing for the mixing of spin-singlet and spin-triplet Cooper pairing ...channels and thus providing a pathway to a non-trivial superconducting state. Materials with a non-centrosymmetric crystal structure and with strong spin-orbit coupling are a platform to realize these possibilities. Here, we report the synthesis and characterisation of high quality crystals of Sn4As3, with non-centrosymmetric unit cell (R3m). We have characterised the normal and superconducting states using a range of methods. Angle-resolved photoemission spectroscopy shows a multiband Fermi surface and the presence of two surface states, confirmed by density-functional theory calculations. Specific heat measurements reveal a superconducting critical temperature of Tc ∼ 1.14 K and an upper critical magnetic field of μ0Hc ≳ 7 mT, which are both confirmed by ultra-low temperature scanning tunneling microscopy and spectroscopy. Scanning tunneling spectroscopy shows a fully formed superconducting gap, consistent with conventional s-wave superconductivity.
We present nonlinear dynamic equations for nematic and smectic
A
liquid crystals in the presence of an alternating electric field and explain their derivation in detail. The local electric field ...acting in any liquid-crystalline system is expressed as a sum of external electric field, the fields originating from feedback of liquid crystal order parameter, and a field, created by charged impurities. The system tends to decrease the total electric field, because it lowers the energy density. This basically nonlinear problem is not a pure academic interest. In the realm of liquid crystals and their applications, utilized nowadays modern experimental techniques have progressed to the point where even small deviations from the linear behavior can be observed and measured with a high accuracy. We follow hydrodynamic approach which is the macroscopic description of condensed matter systems in the low frequency and long wavelength limit. Nonlinear hydrodynamic equations are well established to describe simple fluids. Similar approaches (with degrees of freedom related to the broken orientational or translational symmetry included) have been used also for liquid crystals. However to study behavior of strongly perturbed (well above the thresholds of various electro-hydrodynamic instabilities) liquid crystals, the nonlinear equations should include soft electromagnetic degrees of freedom as well. There are many examples of such instabilities, e.g., classical Carr-Helfrich instability triggered by the competitive electric and viscous torques, flexoelectric instability, and so one. Therefore the self-consistent derivation of the complete set of the nonlinear electro-hydrodynamic equations for liquid crystals became an actual task. The aim of our work is to present these equations, which is a mandatory step to handle any nonlinear phenomenon in liquid crystals.
Accurate forecasting of electricity consumption determines the success of industrial enterprises. Each enterprise, having an accurate prediction of the amount of power consumed, strictly controls it, ...since deviations entail disruptions in work, is subject to fines. Power consumption forecasting for a certain period is the most urgent task in today's electricity market. Existing forecasting methods have individual characteristics and have their advantages and disadvantages. The choice of forecasting methods depends on such major factors as the time for which the forecasting is performed, as well as the amount of information. When forecasting power consumption, it is necessary to take into account various factors related to the technological features of production, organization of equipment operation, etc. The present article describes the proposed method for determining the forecasted values of power consumption parameters in terms of total and specific power consumption, which differs from the existing methods in that it takes into account when forecasting power consumption parameters, the features of production that characterize the production process, the power consumption modes of process equipment, and the impact of technological and operational factors on energy performance that affect the forecast of readings. Accounting for the above factors can significantly simplify and improve the accuracy of forecasting calculations. When determining the forecast values, the components of electricity consumption for the main, auxiliary, and additional production are directly included in the calculation. Besides, the method allows to investigate and optimize the power consumption modes of both a separate production unit and the enterprise as a whole in conjunction with the indicators of processed products and components of the technological process used. The reliability of the method is justified by calculating the energy indicators of a specific section rolling shop of the steel industry.
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