International Journal of Modern Physics B

The aim of this work is to present the magnetized flow of Casson nanomaterials confined due to porous space with stability framework. The slip mechanism for thermal concentration diffusion has been elaborated. The shrinking surface with exponential velocity induced the flow. The new block method is imposed for the simulation process. The resulting systems of ODEs of the third and second orders are solved jointly using the block method, which is appropriate for dealing with the different orders of the system of ODEs. From a physical standpoint, graphs of different profiles for increasing values of the various applied parameters have been drawn and discussed in detail. To satisfy the infinite boundary conditions, we assigned numerical values such that all profiles converge asymptotically at $\eta \to \infty$. Furthermore, numerical results from the block method show that velocity profile declines with rising Casson and porous parameter values, as expected. It is noted that the heat transfer rate enhanced with the thermal slip parameter. A lower thermal profile due to larger Casson fluid parameter is observed.

An event logic graph is a kind of knowledge mapping technology for knowledge inference and simulation analysis, which takes events as the core and portrays the hierarchical system and logical evolution pattern between events. In order to apply it to further improve the accuracy of related studies, such as pedestrian flow evacuation, simulation model optimization and risk prediction. In this paper, we use social network resources, media resources and journal database resources to build our corpus and adopt the explicit event relationship extraction method based on syntactic dependency and the implicit event relationship extraction method based on BERT+Bi-LSTM+Attention+Softmax for the characteristics of explicit event relationship and implicit event relationship, respectively. This paper constructs a pedestrian flow evacuation matter mapping for three typical scenarios and discusses its application path. It is found that once a sound knowledge base of logical reasoning and event logic graph is established, both research on optimization of pedestrian flow evacuation simulation models and research on identification and assessment of pedestrian flow evacuation safety risks will receive excellent support.

This paper theoretically examined the inherent irreversibility in hydromagnetic mixed convection of a radiating adjustable viscosity nanofluid between two concentric inclined cylindrical pipes. Thermodynamics’ first and second laws are incorporated into the two-phase nanofluid flow model problem to explore the repercussions of thermophoresis, Brownian motion, inclination angle, Joule heating, buoyancy forces, viscous dissipation, thermal radiation and entropy generation rate on the overall flow structure with temperature and nanoparticles concentration distribution. The nonlinear model equations of differential types are obtained and numerically addressed through shooting quadrature in conjunction with the Runge–Kutta–Fehlberg integration scheme. Relevant outcomes are graphically represented and discussed. The findings indicate that a rise in the inclination angle lessens the buoyancy effects and diminishes the entropy generation rate in the annular region of the concentric pipes. Within the annulus, the irreversibility due to heat and mass transfer dominates the entropy generation rate. In contrast, an upsurge in magnetic field intensity decreases the entropy generation rate and the Bejan number.

Possibility of having different topological phases by time-periodic external field encourages people who wish to manipulate the properties of the materials as their will for the various kinds of systems including a honeycomb nanoribbon. We study bulk-edge correspondence by looking at the change in the value of the first Chern number of a specific band, which reflects the bulk properties, together with the change of associated edge states in quasienergy spectrum when the honeycomb nanoribbon is exposed to circularly polarized laser field. Various topological phase transitions are observed as the intensity of the laser field is raised up and we classify them in two categories. In the first category, when the frequency is sufficiently high, the system undergoes simple transition from trivial phase to topological one, reflected by the sudden jump in the value of Chern number from 0 to 1 and the appearance of two crossing edge states in the spectrum. Whereas, in the second category where the frequency is low enough, anomalous transitions are drawn, having several nonzero values of Chern number, and band folding prevails, often disappearing depending on the laser intensities. The results confirm the bulk-edge correspondence in periodically driven systems and will contribute to future material designs.

This paper is a key contribution with respect to the applications of solitary wave solutions to the unique solution in the presence of the auxiliary data. Hence, this study provides an insight for the unique selection of solitons for the physical problems. Additionally, the novel numerical scheme is developed to compare the result. Further, this paper deals with the stochastic Fisher-type equation numerically and analytically with a time noise process. The nonstandard finite difference scheme of stochastic Fisher-type equation is proposed. The stability analysis and consistency of this proposed scheme are constructed with the help of Von Neumann analysis and Itô integral. This model is applicable in the wave proliferation of a viral mutant in an infinitely long habitat. Additionally, for the sake of exact solutions, we used the Riccati equation mapping method. The solutions are constructed in the form of hyperbolic, trigonometric and rational forms with the help of Mathematica 11.1. Lastly, the graphical comparisons of numerical solutions with exact wave solution with the help of Neumann boundary conditions are constructed successfully in the form of 3D and line graphs by using different values of parameters.

The objective of current communication is to study heat transfer phenomenon for slip flow of viscous fluid due to wavy channel with general cosine function boundaries and fixed amplitude. The walls along with slip boundary constraints are kept at different temperatures. The flow is incompressible and Newtonian with AIS as a predicting material being used to check the fluids and thermal properties. The Navier–Stokes expressions with 2D flow regime subject to heat transfer due to convection are used to develop the simulations. A parametric theoretical assumptions analysis is performed for specified range of Reynolds number (100–1000) with upper and lower surface vibration periods of 1 to 6. The results are displayed with graphs, surface and contours plots and first, ever a novel work was done to represent the percentage change in velocity magnitude and local Nusselt number as surface plots and contours, respectively. The results are authentic due to mesh independent study and verification with the experimental correlation. A periodic flow at the lower wall was deducted. The maximum and average rotation rates attain a linear relationship with Reynolds number and their correlation was found. The simulations show the strict relationship of Reynolds number and the geometry of the channel with shear rate. The pressure gradient in $y$-direction was found minimum in trough and maximum in the crest region. It has been observed that the boundary friction is reduced due to periodic variation of walls surface.

This work reports an $n$-type GaN/InGaN/GaN heterostructure vertical double-gate tunnel field-effect transistor (VTFET) using exhaustive calibrated simulation for the first time. Investigation has been done for the proposed structure by including a polarization layer of InGaN near the source-channel junction. From the analysis, it has been observed that after the introduction of polarization layer near the source-channel interface, drain current increases due to the increase in charge concentration (2DEG) near the interface due to inter-band tunneling. Value of 2DEG concentration achieved post introducing the polarization layer is $10^{18}$ ${\mathrm{\text{cm}}}^{-2}$. The reported structure is optimized using parametric sweep optimization technique. Here, a detailed dc and analog/RF performance estimation has been done for the structure with heterostructure. In-depth sensitivity analysis has been done for the structure with the polarization layer. It is reported that the structure with HfO₂ as the dielectric material with $t_{\mathrm{\text{ox}}}$ of 2 nm and with gate metal work function of 5.8 eV gives the optimum performance at 300 K. Further, it demonstrates high cutoff frequency ($f_t)$ and gain bandwidth product (GBW) as 1000 GHz and 300 GHz, respectively. Hence, the reported structure is a better alternative for high-power steep switching analog and RF applications.

This research study has developed a mathematical model for malaria disease which is not only applicable for the case when the recovered humans return to the susceptible class, but also provides the directions for the case when the recovered humans also return to the infectious class. The model is simulated by using the Euler, Runge–Kutta-4 (RK-4), and nonstandard finite difference (NSFD) scheme. Firstly, the model is simulated by the Euler scheme and RK4 scheme and obtained graphical depiction for the endemic equilibrium as well as for the disease-free equilibrium (DFE). Then the mathematical model of malaria is simulated by an NSFD scheme and its graphical interpretation shows that it is suitable for all step sizes, i.e., it gives converging results even for very large step sizes. It is shown that the NSFD scheme is an unconditionally stable numerical scheme at a large step size. It is concluded that parameter $R$ is greater than unity in the disease manifestation of the landlord population in the long term and when the parameter $R$ is less than unity then the DFE is asymptotically stable.

In classical electrodynamics, by motion for either the observer or the media, it is always naturally assumed that the relative moving velocity is a constant along a straight line (e.g., in inertia reference frame), so that the electromagnetic behavior of charged particles in vacuum space can be easily described using special relativity. However, for engineering applications, the media have shapes and sizes and may move with acceleration, and recent experimental progresses in triboelectric nanogenerators have revealed evidences for expanding Maxwell’s equations to include media motion that could be time and even space dependent. Therefore, we have developed the expanded Maxwell’s equations for a mechano-driven media system (MEs-f-MDMS) by neglecting relativistic effect. This paper first presents the updated progresses made in the field. Second, we extensively investigated Faraday’s law of electromagnetic induction for a media system that moves with an acceleration. We concluded that the newly developed MEs-f-MDMS are required for describing the electrodynamics inside a media that has a finite size and volume and move with and even without acceleration. The classical Maxwell’s equations are to describe the electrodynamics in vacuum space when the media in the nearby move.

The most difficult aspect in electrochemical synthesis of graphene oxide (GO) is preventing graphite from disintegrating on the surface of the anode, which affects microstructural characteristics and yield. In this study, the effect of applied potential, electrolytic temperature, and types of electrolytic solution on yield, anode surface disintegration and microstructural properties of electrochemically synthesized GO has been investigated. The GO has been synthesized in an aqueous solution of 1 M piranha solution and sulfuric acid (${\mathrm{\text{H}}}_2{\mathrm{\text{SO}}}_4$) via electrochemical method by applying 24 V DC power source. After that, the GO was thermally reduced at around 650${\circ }^{}$C in a muffle furnace, and cooled down inside the muffle furnace. The yield, pH of the electrolytic solution, and anode surface disintegration all looked to be affected by the applied voltage and electrolyte temperature. Between the temperatures of 50${\circ }^{}$C and 70${\circ }^{}$C, the maximum yield was observed. During UV–Vis and XRD investigation, the absorbance, crystal structure, and interplanar distance appear to be unaffected by the reduction temperature, high voltage, electrolyte temperature and hydrogen peroxide addition. As demonstrated by Raman spectra, TEM, FE-SEM, AFM, and TGA analysis, high voltage, electrolyte temperature, and hydrogen peroxide addition have an important effect on the degree of defect, microstructure, and oxygen percentage, surface roughness and thermal stability of thermally reduced graphene oxide (TRGO).