Bulk viscosity in strong and electroweak matter

For temperatures [Formula: see text] ranging from a few MeV up to TeV and energy density [Formula: see text] up to [Formula: see text][Formula: see text]GeV/fm3, the bulk viscosity [Formula: see text] is calculated in nonperturbation (up, down, strange, charm and bottom) and perturbation theories with up, down, strange, charm, bottom and top quark flavors, at vanishing baryon-chemical potential. To these calculations, results deduced from the effective QCD-like model, the Polyakov linear-sigma model (PLSM), are also integrated in. The PLSM merely comes up with essential contributions for the vacuum and thermal condensations of the gluons and the quarks (up, down, strange and charm flavors). Furthermore, the thermal contributions of the photons, neutrinos, charged leptons, electroweak particles and scalar Higgs boson are found very significant along the entire range of [Formula: see text] and [Formula: see text] and therefore could be well integrated in. We present the dimensionless quantity [Formula: see text], where [Formula: see text] is a perturbative scale and [Formula: see text] is the entropy density and conclude that [Formula: see text] exponentially decreases with increasing [Formula: see text]. We also conclude that the resulting [Formula: see text] with the nonperturbative and perturbative QCD contributions nonmonotonically increases with increasing [Formula: see text]. But with nearly-entire standard model contributions considered in this study, [Formula: see text] almost-linearly increases with increasing of [Formula: see text]. Apparently, these results offer a great deal to explore in astrophysics, cosmology and nuclear collisions.

Heat Transfer Across Tube Banks With a Passive Control Vortex Generator in Steady One-Directional and Oscillatory Flows

Fluid can flow in one-directional (normal flow) or oscillatory conditions. Fluid flow in some energy system involved oscillatory flow condition. The use of vortex generator has been proven to improve heat transfer in the case of one-directional flow but the impact of vortex generator in oscillatory flow condition is yet unknown. This study focusses on the heat transfer performance across a heated tube banks using a Computational Fluid Dynamics (CFD) model. Two flow conditions were modelled: steady one-directional and oscillatory flow conditions. Two-dimensional CFD models of steady flow and oscillatory flow were solved using the SST k-? turbulence model for two different cases of heated tube banks with and without the vortex generators. The heat transfer performance for both flow conditions were analysed by considering a heat transfer parameter known as Colburn-j factor. Results showed that the use of a vortex generator increased the heat transfer enhancement, regardless of the flow conditions. However, it is also noted that the heat transfer behaviour in a steady flow and an oscillatory flow is not the same, especially with the appearance of secondary flows in the system. The difference is discussed with respect to dimensionless quantity of Colburn j-factor, the non-dimensionless quantity, and the amplitude of temperature field. The result indicates that the heat equation in the steady flow condition is not very suitable to be directly used in oscillatory flow conditions. Appropriate heat equation needs to be properly addressed for situations that involve oscillatory flow motion.

Temperature effect on thermal-hydraulic performance of one-pass counter-current flow shell-and-tube heat exchanger and upon its design

A methodology of design and analysis of thermal-hydraulic performance for a single pass 1-1 counter-current flow shell and tube heat exchanger (CCFSTHE) TEMA E type has been established. The temperature effect on the thermo-physical properties of flowing fluids and on the overall coefficient of heat transfer along the heat exchanger is incorporated in our approach, as well as the coupling between different thermal and hydraulic parameters. It has been noted that the correction factor (F) in the HAUSBRAND formula is not included. Our method brings us to a new dimensionless quantity (MKA) which links the calculation parameters of the heat exchanger to the thermo-physical properties. This dimensionless quantity relates the number of transfer units (NTU) to the heat flow ratio (R). The results based on our models show a pronounced deviation compared to the model reported in the literature (NTU method). This deviation may be related to a temperature effect not included in the literature model. It has been shown that the results derived from our models are in a good agreement with experimental data. Our new method, named MKA - method, could be a useful tool for theoretical and experimental studies of the design and analysis of the single pass 1-1 CCFSTHE thermal and hydraulic performance for 0 ? R ?1.

Varying Newton Constant and Black Hole to White Hole Quantum Tunneling

The thermodynamics of black holes is discussed for the case, when the Newton constant G is not a constant, but it is the thermodynamic variable. This gives for the first law of the Schwarzschild black hole thermodynamics: dSBH=−AdK+dMTBH, where the gravitational coupling K=1/4G, M is the black hole mass, A is the area of horizon, and TBH is Hawking temperature. From this first law, it follows that the dimensionless quantity M2/K is the adiabatic invariant, which, in principle, can be quantized if to follow the Bekenstein conjecture. From the Euclidean action for the black hole it follows that K and A serve as dynamically conjugate variables. Using the Painleve–Gullstrand metric, which in condensed matter is known as acoustic metric, we calculate the quantum tunneling from the black hole to the white hole. The obtained tunneling exponent suggests that the temperature and entropy of the white hole are negative.

Use of Amount-of-Substance Terminology and Equations in Field Desorption Theory

This note proposes that the theories of field evaporation and field desorption, as used in atom-probe microscopy and related atomic-level contexts, should be consistently formulated in terms of a set of “seven-dimensional (7-D)” formulae and equations that involve the physical quantity “amount of substance”, but make use of an atomic-level constant effectively equal to “one atom” (or, more generally, “one entity”). It is argued that the term “count” should be introduced as an alternative name (more suited to atomic-level contexts) for the quantity “amount of substance”. For field evaporation/desorption theories, relevant definitions and formulae are proposed, and compared with the “six-dimensional” system (based on the dimensionless quantity “number of atoms/entities”) sometimes used in the literature. Advantages of using a 7-D system are noted. It is argued that there is also an increasing need for a comprehensive system of official nomenclature for atomic-level constants and units, for all three of the extensive quantities “mass”, “electric charge” and “amount of substance”. It is also argued that, in the longer term, considerations of the kind being proposed here for field evaporation/desorption theories might usefully be applied more generally in atomic-level rate theory.

Varying Newton Constant and Black Hole to White Hole Quantum Tunneling

The thermodynamics of black holes is discussed for the case, when the Newton constant G is not a constant, but is the thermodynamic variable. This gives for the first law of the Schwarzschild black hole thermodynamics: d S BH = − A d K + d M T BH , where the gravitational coupling K = 1 / 4 G , M is the black hole mass, A is the area of horizon, and T BH is Hawking temperature. From this first law it follows that the dimensionless quantity M 2 / K is the adiabatic invariant, which in principle can be quantized if to follow the Bekenstein conjecture. From the Euclidean action for the black hole it follows that K and A serve as dynamically conjugate variables. This allows us to calculate the quantum tunneling from the black hole to the white hole, and determine the temperature and entropy of the white hole.

Exotic properties of materials and the necessity to invoke the dimension of angle (𝜃) and the orbital degrees of freedom of s electrons

Currently, many new materials including nanomaterials exhibit exotic properties like, mention a few, unconventional superconductivity, reduced magnetism, reduced Pauli repulsion. These exotic properties could not be explained completely with the existing quantum mechanical theories which did not take into account the dimension of angle. Now, there arises a necessity to invoke the forgotten dimension of angle, for explaining these exotic interesting properties. So far angle is considered as a dimensionless quantity even though its all time partner [Formula: see text] is endowed with dimension. In materials, where surface plays a dominant role, this new dimension, of angle becomes an important tool for exploring their morphology and exotic properties. This new dimension of angle restores the orbital degrees of freedom to the s electrons whose orbital degrees of freedom are suppressed ([Formula: see text]). It compensates for the missed signature of s electron orbital angular momentum.

Overconstrained gravitational lens models and the Hubble constant

ABSTRACT It is well known that measurements of H0 from gravitational lens time delays scale as H0 ∝ 1 − κE, where κE is the mean convergence at the Einstein radius RE but that all available lens data other than the delays provide no direct constraints on κE. The properties of the radial mass distribution constrained by lens data are RE and the dimensionless quantity ξ = REα″(RE)/(1 − κE), where α″(RE) is the second derivative of the deflection profile at RE. Lens models with too few degrees of freedom, like power-law models with densities ρ ∝ r−n, have a one-to-one correspondence between ξ and κE (for a power-law model, ξ = 2(n − 2) and κE = (3 − n)/2 = (2 − ξ)/4). This means that highly constrained lens models with few parameters quickly lead to very precise but inaccurate estimates of κE and hence H0. Based on experiments with a broad range of plausible dark matter halo models, it is unlikely that any current estimates of H0 from gravitational lens time delays are more accurate than ${\sim} 10{{\ \rm per\ cent}}$, regardless of the reported precision.

A renormalized HVT approach for a class of central potential wells

An investigation is carried out to consider a renormalized HVT approach in the context of s-power series expansions for the energy eigenvalues of a particle moving non-relativistically in a central potential well belonging to the class V(r)=−Df(rR), D>0 where f is an appropriate even function of x=r/R and the dimensionless quantity s = (h^2/2μDR)^{1/2} is assumed to be sufficiently small. Previously, the more general class of central potentials of even power series in r is considered and the renormalized recurrence relations from which the expansions of the energy eigenvalues follow, are derived. The s-power series of the renormalized expansion are then given for the initial class of potentials up to third order in s (included) for each energy-level Enl . It is shown that the renormalization parameter Κ enters the coefficients of the renormalized expansion through the state-dependent quantity a_{nl}χ^{1/2} =a_{nl}(1+K ((−d_1D)R^2))^{½}, a_{nl}=(2n+l+32). The question of determining χ is discussed. Our first numerical results are also given and the utility of potentials of the class considered (to which belong the well-known Gaussian and reduced Poschl- Teller potentials) in the study of single–particle states of a Λ in hypernuclei is pointed out.

The softness distribution index: towards the creation of guidelines for the modeling of soft-bodied robots

Modeling soft robots is not an easy task owing to their highly nonlinear mechanical behavior. So far, several researchers have tackled the problem using different approaches, each having advantages and drawbacks in terms of accuracy, ease of implementation, and computational burden. The soft robotics community is currently working to develop a unified framework for modeling. Our contribution in this direction consists of a novel dimensionless quantity that we call the softness distribution index (SDI). The SDI for a given soft body is computed based on the distribution of its structural properties. We show that the index can serve as a tool in the choice of a modeling technique among multiple approaches suggested in literature. At the moment, the investigation is limited to bodies performing planar bending. The aim of this work is twofold: (i) to highlight the importance of the distribution of the geometrical and material properties of a soft robotic link/body throughout its structure; and (ii) to demonstrate that a classification based on this distribution provides guidelines for the modeling.