International Journal of Modern Physics B最新文献

Structure complexity, adequate electronic character and congenital lower thermal conductivity of zintl phases result in designing thermoelectrics of tremendous efficiency. Such qualities of zintl phases embolden us to present a detailed study of SmMg₂X₂ (X = P, As, Sb, Bi) zintl compounds by first principles. The structural characteristics fit well with the existing data. Electronic properties of titled compounds are scrutinized by adopting PBE-GGA, TB-mBJ and hybrid (YS-PBE0) potentials. The band structure calculations through TB-mBJ and hybrid (YS-PBE0) proclaim the semiconducting behavior of compounds and there is a shrinkage of band gap by changing X anion from P to Bi. The density of states (DOS) calculation reveals that there is a major contribution of Sm-f states and Mg atom in valence band while in conduction band, the prominent role is offered by Sm-d states and p states of X anion. Similarly, the temperature-dependent thermoelectric properties are scrutinized by using BoltzTraP2 code embedded within WIEN2k software for with and without spin–orbit coupling (SOC) and also through hybrid (YS-PBE0) functional. SOC, but even more hybrid functional, has been shown to have a significant effect on the transport behavior. Optimized values of carriers’ concentration are achieved which subsidize thermoelectric parameters like power factor (PF), Seebeck coefficient ($S)$ and thermoelectric figure of merit (ZT) at elevated temperature. The compounds show excellent thermoelectric performance in the studied temperature range.

In this work, we employed the transfer-matrix method to obtain the transmittance spectrum of a defective one-dimensional photonic crystal composed of polymer materials. We consider that the dielectric constant of the polymers is a function of the applied pressure, and the cavity is infiltrated by plasma cells. When blood plasma concentration and cavity thickness are increased, we observe a defective mode tuned to long wavelengths within the photonic band gap. By calculating the energy stored in the cavity, a maximization of the quality factor to $\sim 2.55\times 10^4$ for a 2350$$nm cavity was observed. In addition, we report that as the applied pressure increases, the defective mode shifts to shorter wavelengths, accompanied by a decrease in the quality factor to $2.30\times 10^4$ for a pressure of 100$$MPa.

This research paper investigates a two-dimensional couple stress flow of hybrid nanofluid (HN) over a nonlinear stretching surface with heat transfer analysis. HNs are well-known for their exceptional heat transfer properties compared to conventional fluids. The mathematical modeling of the problem involves the formulation of basic governing equations, namely, continuity, momentum and energy equations. To simplify the analysis, a similarity transformation technique is employed to convert the dimensional NLPDEs into dimensionless NODEs. Subsequently, the obtained governing equations are analytically solved using the HAM. The investigation explores the impact of several parameters, including magnetic field inclination, slip parameter, couple stress parameter, nanoparticle volume fraction, nonlinear stretching parameter, EN, thermophoresis parameter and PN. This study presents graphical representations of temperature and velocity distribution to visualize the effects of these parameters on the HN flow. Furthermore, different graphs and tables are employed to explain the impact of the factors on SF and NN. Notably, the results indicate that the HN exhibits significantly enhanced heat transfer properties over the base fluid, particularly under the influence of an inclined magnetic field. This research is expected to contribute to the advancement of the field of condensed nanostructure and nanomaterials, opening new avenues for further exploration in heat transfer enhancement applications.

Various approaches have been used in the literature for eliminating nonresonant levels in atomic systems and deriving effective Hamiltonians. Important among these are elimination techniques at the level of probability amplitudes, operator techniques to project the dynamics on to the subspace of resonant levels, Green’s function techniques, the James’ effective Hamiltonian approach, etc. None of the previous approaches is suitable for deriving effective Hamiltonians in intracavity situations. However, the James’ approach does work in the case of only two-photon transitions in a cavity. A generalization of the James’ approach works in the case of three-photon transitions in a cavity, but only under Raman-like resonant conditions. Another important approach for adiabatic elimination is based on an adaptation of the Markov approximation well-known in the theory of system–bath interactions. However, this approach has not been shown to work in intracavity situations. In this paper, we present a method of adiabatic elimination for atoms inside cavities in the presence of multiphoton transitions. We work in the Heisenberg picture, and our approach has the advantage that it allows one to derive effective Hamiltonians even when Raman-like resonance conditions do not hold.

The aim of this work is to present a natural convective and squeezing flow model of two-dimensional couple stress nanofluid which is flowing on the sensory surface with variable fluid viscosity. The fluid flowing on a microcantilever sensory surface and squeezing is happening at free stream. The sensor is also useful to detect the movement of fluid and the variations in thermal and solutal rates. The Cattaneo–Christov model is adopted along with nanoparticle and chemical reaction to explore the transmission of heat and mass rates. The analysis of heat transmission in non-Newtonian couple stress fluid flowing on squeezed sensory surface by using the Cattaneo–Christov heat conduction model has various industrial and scientific applications including the polymer processing, wastewater treatment, chemical reactors, biomedical flows, cooling and heating processes in industries, heat exchangers, microfluidics, oil and gas industries. All the assumptions are applied in the basic governing laws laws and then we get the model of the partial differential equations. The governing model of equations is transmuted into ordinary differential equations form via the transformations and then the numerical results of these ODE’s are examined with a well-defined numerical technique “Shooting Method”. For higher inputs of couple stress, squeezing index and permeability velocity, the fluid’s internal velocity decreases. Because of the Prandtl number and thermal relaxation coefficient, the heat transfer mechanism slows down. Mass transfer increases for greater inputs of the thermal diffusivity coefficient and decreases due to concentration relaxation. Further, the numerical dependency of emerging parameters on the skin friction is illustrated in tabular form. The parametric effects on the model (velocity, temperature and concentration) are introduced using numerical values shown in the table.

This research captures nonlinear thermo-solutal buoyancy (i.e., nonlinear mixed convection) impact in nanofluid flow based on magnetized Casson model. The generalized porosity concept (i.e., Darcy–Forchheimer relationship) is employed by considering incompressible liquid that saturates the porous space. Effects of thermophoresis, Robin conditions, thermo-solutal stratifications and Brownian diffusion are accounted. Consideration of transpiration phenomenon captures suction/injection aspects. Fluid mechanics basic laws are depleted to simplify the governing rheological expressions. A transformation procedure is then employed to convert the nonlinear governing partial systems into differential systems. Homotopy methodology is used to obtain analytical solutions and convergence is ensured. Graphical and tabular outcomes are presented to address the importance of emerging variables.

The essence of the current examination is to carry out thermofluid parametric sensitivity with time-varying thermal migration of chemically reactive tiny species across an oscillating infinite plate surface. The impact of thermal motile tiny particles under the influence of many other oscillating flow parameters has yet to be investigated; hence the results obtained in this research are novel. Using a suitable non-dimensional variable, the leading PDEs (partial differential equations) are transmuted into dimensionless PDEs, ensuring equations are numerically solved using the MAPLE built-in approach. The numerical values produced in a limited scenario are linked with the outcomes found in the literature to validate the precision of the numerical approach utilized. The fluctuations in the profiles of the velocity, temperature, and concentration, in addition to the wall friction and rate of thermal and solutal transport, are illustrated via graphs and tables due to the modification of the critical parameters. The endmost results of the study concede that increasing permeability quantity and thermal and solutal buoyancy impellers intensify the fluid velocity. In contrast, a converse tendency is perceived with magnetic parameter and also, wall friction acts opposite to the velocity. The fluid temperature attenuated with dilation of the Prandtl number and radiation parameter, whilst a contrary trend was perceived with Eckert number. The increasing thermo-diffusion helps to develop fluid concentration whilst the Schmidt number and chemical reaction displayed opposite trend. Further, we achieved a tremendous conformity between the current findings and genuine results in the literature.

To control the emission of SO₂ from flue gas into the atmosphere while considering the capture and collection of greenhouse gas CO₂, the adsorption behavior of a binary mixture of SO₂ and other gases in flue gas (O₂/N₂/H₂O/CO${}_2)$ in (10, 10) carbon nanotube (CNT) was simulated using grand canonical Monte Carlo (GCMC) simulation. The adsorption and separation performance of SO₂ in CNTs with a diameter range of 0.81–1.63 nm for the five-component mixture gas was also analyzed. The findings suggest that the adsorption and separation of SO₂ are primarily influenced by CO₂ (reduction of adsorption capacity by about 50%, separation coefficient of SO₂/CO₂ is lowest) with this effect being more pronounced under high pressure. Meanwhile, it was observed that CNTs with larger pipe diameters exhibit higher SO₂ adsorption capacity, but relatively lower SO₂/CO₂ selectivity and lower stability. On the other hand, CNTs with smaller diameters have relatively lower adsorption capacity for SO₂, but exhibit good selectivity and stability (under different pressure) for SO₂/CO₂. Based on the statistical analysis of SO₂ adsorption capacity and SO₂/CO₂ selectivity, it was determined that (6, 6) CNT with a diameter of 0.81$$nm can exhibit excellent SO₂ adsorption and separation performance at atmospheric pressure, while appropriate large diameter CNTs should be selected for flue gas treatment under high pressure.