International Journal of Modern Physics B

The concentrations of forming defects during phase transitions (PTs) and elastic coefficients in the ${\text{Cu}}_{1.95}$${\text{Ni}}_{0.05}$S compound were determined based on differential thermal analysis (DTA) data $\mathrm{\Delta }{T}_y(T)$. The sample was studied under the influence of $\gamma$ irradiation (at a dose of 25 Mrad) and it was shown that the $T_y(T)$ curves coincide each other before and after irradiation. It was established that $\alpha$, $\beta$, $\gamma$ modifications are commensurate when heating the sample. A certain number of defects in S atoms at lattice sites and defects in Cu atoms (also Ni atoms) in interstitial sites of the sublattice are some of the causes of lattice rearrangement.

In this paper, the time incapable illimitable paraxial wave equation which is used in Kerr-media is being investigated. The paraxial wave equation has important applications in the light beam interaction within the ripple unit and also in calculation of the light emission outside the fluctuation. We have applied two techniques, namely, He’s variational and Hirota bilinear techniques to extract the diversity of optical wave structures. The diversity of the wave solutions include the three-wave hypothesis, periodic cross kink, lump periodic, mixed type wave solutions and breather wave. The 3D, 2D, and their corresponding contour plots of the earned solutions are successfully drawn for the real, and imaginary behaviors by selecting the suitable values of parameters.

A narrow-gap semiconductor FeGa₃ has attracted much interest for its unusual physical properties, in particular, for its colossal thermopower at low temperatures for which the origin has not been elucidated yet. In this study, the temperature-dependence data of the conductivity, the Hall coefficient, and the Seebeck coefficient on FeGa₃ samples reported by Wagner-Reetz et al. [Phys. Rev. B 90, 195206 (2014)] have been analyzed with including the effects of impurity Hubbard bands. As a result, it is shown that, contrary to the claim by Wagner-Reetz et al., the large negative peak of the Seebeck coefficient is not due to the phonon-drag effect but due to hopping conduction in the impurity Hubbard bands. The significant effect of nonpolar-optical-phonon scattering on free-electron conduction is also pointed out.

This paper discusses the impacts of velocity, temperature, and solutal slip on the mass and heat transfer characterization of MHD mixed convection Casson fluid flow along an exponential permeable stretching surface with chemical reaction, Dufour and Soret effects. The Casson fluid is supposed to flow across an exponentially stretched sheet, together with the exponential temperature and concentration fluctuations of the fluid. As governing equations, the momentum, energy and species concentration equations are constructed and represented as PDEs. Following that, these equations were converted via the similarity transformation into ODEs. Finally, the ODEs are numerically solved using the Keller-box method with MATLAB software’s algorithm. Expressions are produced for the fluid flow, temperature and concentration gradients. We also determined the physical variables from which the friction factor, rate of mass and heat transfer are attained for engineering purposes. Using graphs and tables, the impacts of altered physical characteristics on flow amounts are explored. The consistency and validity of our outcomes revealed a significant degree of agreement when comparing them to previously published studies. The findings reveal that raising the Soret and Dufour parameter enhances the velocity profile at the wall, but the converse is true for increasing the velocity slip factor.

Rich club is a special phenomenon in complex networks. It refers to the nodes with high degrees (i.e., rich nodes) that tend to connect with each other to form a “rich club”. This phenomenon exists in many real networks, especially in social networks. However, there are also some networks not having this phenomenon, for example, in many biological networks. Thus, a natural question comes up: do these rich nodes contact with each other through an “agent”? Two rich nodes do not connect directly, but they can establish a connection by an “agent”, i.e., they can connect with each other within two steps. If the rich nodes tend to connect with each other within two steps, we say that they form a “2-step rich club”. The traditional rich club is then called “1-step rich club”. In this paper, we aim to design one method to detect the “2-step rich club” phenomenon in real networks and check whether this new “2-step rich club” phenomenon commonly exists in real networks. We find that most networks with “1-step rich club” will also have “2-step rich club”. However, there also exist few networks having “2-step rich club” structure while not having “1-step rich club” structure. In particular, either 1-step rich-club phenomenon or 2-step rich-club phenomenon exists in most social networks.

The consideration of thermo-capillary or Marangoni convection developed through surface tension continuously remains a focus of immense importance for engineers and scientists. This is due to their ample utilizations that is, thin films spreading, welding, nuclear reactors, materials science, semiconductor processing, crystal growth melts, etc. Having such usefulness of Marangoni convection in view, our objective here is to formulate the non-Newtonian rheological Williamson liquid capturing mixed convection and transpiration aspects. Modeling is done considering radiative magnetohydrodynamic flow. Interface temperature of both dust particles and fluid is selected as a nonlinear (quadratic) function of interface arc-length. Resulting systems are rendered to ordinary problems via opposite variables. Computational analysis is performed considering finite difference scheme. Features of embedded factors against nondimensional quantities are elaborated graphically.

Nowadays, the heat thrust liquid electric heater is generally used in profitable applications since it protects upto 2–3 times the energy of ordinary liquid electric heater. The heat pump makes use of a refrigerant for its process. The small-temperature refrigerant engrosses permitted heat from full of atmosphere midair in the evaporator which is crushed by an extremely well-organized electrical compressor to an extraordinary-temperature and high-pressure vapor refrigerant. For entire heat transfer connoisseurs, heat transfer performance in cooling and heating applications has become a top priority. Hence, research towards new heat transfer fluids is extremely intense and challenging. This investigation examines flow and heat transfer analysis in axisymmetric magnetohydrodynamic flow polyethylene glycol (PEG)-based nanofluid, hybrid nanofluid and ternary hybrid nanofluid flow induced by a swirling cylinder. Flow and heat transfer are analyzed and compared for three cases PEG-based copper oxide, magnesium oxide and zirconium oxide ternary nanofluid (PEG$+$ZrO₂$+$CuO$+$MgO), PEG-based copper oxide (PEG$+$CuO) nanoparticles and PEG-based zirconium and magnesium oxide hybrid nanofluid (PEG$+$ZrO₂$+$MgO). Shooting technique (R–K fourth-order) is employed to work out the flow equations numerically. Simulated results are displayed through graphs. The computational results are validated with the published research work and a modest concurrence is found. The main outcome of this study is found to be as follows: It is interesting to note that $C_{fx}\mathrm{\text{Re}}(\frac{x}{R})$ is lesser in nanofluid case compared with ternary and hybrid nanofluid cases. It is found that $C_{f\varphi }\mathrm{\text{Re}}(\frac{G}{HR})$ is more in ternary hybrid nanofluid compared with hybrid and nanofluid cases. Overall, it is observed that heat transfer rate is higher in nanofluid compared with ternary and hybrid nanofluid cases whereas lesser rate of heat transfers in ternary nanofluid case.

This research explored the influences of entropy generation on bioconvected nanoliquid flow through the porous cavity filled with nanofluid and gyrotactic microbes. The porosity term in the momentum equation is summarized by the implementation of Darcy’s formula through Boussinesq estimation. The novelty of this study is to investigate entropy generation in cavity by augmenting the convection generated by the phenomenon of Brownian motion, thermophoresis of nanofluid flow and the bioconvection due to swimming of microorganisms. The governing partial differential equations (PDEs) are highly nonlinear and are nondimensionalized through the suitable similarity constraints. The transformed PDEs are tackled via implementation of finite difference method (FDM). The reaction of entropy generation and Bejan number against various quantities like bioconvection Rayleigh number ($\mathrm{\text{Rb}}=1$–100), Rayleigh number ($\mathrm{\text{Ra}}=1$–100), Peclet number ($\mathrm{\text{Pe}}=0.1$–0.9) and ratio of buoyancy ($\mathrm{\text{Nr}}=0$–1) are reported and visualized. The entropies by theliquid friction, heat transportation, mass transmission and microorganisms are focused. Upsurge in Nr (0.3–0.5) and Pe (0.1–0.15) accelerated the maximum of entropy due to microorganism by 7% and 44%, respectively. Here, an increment in Ra, Rb, Pe and Nr affects the distribution pattern of total entropies and Bejan number consistently. The higher Lewis number caused a decrement in the total entropy by liquid friction.

In this work, three passive techniques (ferrofluid, porous zone, curved surfaces) have been merged with one active technique (electric force) to enhance the convective rate. The permeable enclosure contains two curved walls and two straight walls which are not stationary. The concentration of ferrofluid within the domain is constant and associated formulations for properties of ferrofluid have been applied in modeling in which no slip velocity exists among particles. With define, measure, analyze, improve and control (DMAIC), the vorticity equation for partial equations which contain the source terms of electrohydrodynamic (EHD) and permeability, final equations have been achieved and for finding the solution combination of two basic techniques were utilized. Low deviation with a prior article in the validation procedure indicated a good agreement. Nu can augment around 0.49% if platelet particles were applied rather than sphere. Utilizing radiation in simulation makes Nu augment around 82.27%. Elevating Da in the absence and appearance of EHD leads to an augment of Nu around 145.01% and 393.38%. Appearance of EHD enhances the Nu about 96.04%.

Demonstration of heat release phenomenon by employing the numerical approach is the main purpose of current research. Water as PCM was combined by particles and homogeneous mixture was assumed. Various shapes of powder with different concentrations were employed. The unsteady energy equation involving nanomaterial properties and freezing source term has been analyzed and for finding the solution, the Galerkin technique was employed. The adaptive grid generates greater number of elements in solid front region. Implicit formulations for unsteady terms were implemented and automatic time step was employed in software. Solid front changes with alteration of shapes of nanopowder and its fraction. With fraction augmentation, freezing finishes in lower time. The needed time diminishes by about 10.29% and 13.78%, respectively. Changing the shape of particles to the biggest level makes the period decline by less than 4.8% and 8.4%. A greater fraction of nanomaterial leads to a higher effect on the shape of nanomaterial.