Modern Physics Letters B

In this paper, the effect of the distribution of ceramic particles WC in Cu matrix on the nano-cutting behavior was investigated using molecular dynamics, and the cutting force, friction coefficient, machined surface quality, sub-surface damage depth, atomic displacement and internal defects were systematically studied, and the performance comparison at different cutting speeds was also investigated. It was found that due to the location of the WC phase, the overall removal of the material by the tool can be divided into the following three ways: When WC particles are above the cutting plane, there is less fluctuation in cutting forces and friction coefficients, and less impact on machined surface and subsurface damage; When the WC particles are below the cutting plane, the fluctuation of cutting force and friction coefficient is slow. Meanwhile, shallow craters are produced at the WC location; When the center of mass of WC particles is on the same level as the cutting plane, the cutting force and friction coefficient fluctuate drastically, the quality of the machined surface deteriorates sharply, and at the same time the hard particles pulled out by the tool remain on the machined surface. It was also found that the WC particles underwent different degrees of counterclockwise deflection in the three stages and caused a diversion of the atomic displacement in front of the tool. In addition, different degrees of dislocation plugging are formed between the WC and the tool at different positions, and the density of dislocation lines increases, which makes the substrate near the WC particles strengthened.

The aim of this paper is to discover some new exact solutions for two kinds of nonlinear Schrödinger equation (NLSE), including the (2+1)-dimensional NLSE and the derivative NLSE, through the use of the variational principle method and amplitude ansatz method. We will find the solutions to these equations by selecting a trial function with a single nontrivial variational parameter, and it is continuous at all intervals in three cases from a region of a rectangular box, then using this trial function to obtain the functional integral and the Lagrangian of the system without any loss. After that, we approximate this trial function by quadratic polynomials with two free parameters rather than a piecewise linear ansatz function. Similarly, this trial function will be approximated by the tanh function. Additionally, we accept several new types of soliton solutions, including bright solitons, dark solitons, bright–dark solitary wave solutions, rational dark–bright solutions, and periodic solitary wave solutions. Also, conditions for the stability of the solutions will be proposed. These explanations are of great importance in the fields of applied science and engineering. The results will be shown through different types of graphs, including 2D, 3D, and contour plots.

This novel study unfolds the heat and mass transfer investigation of Williamson nanofluid (WNF) through a porous medium past a stretching plate, along with considering heat generation/absorption. Nanoparticles hold significant significance in thermal engineering, industrial operations, and biomedical advancements, contributing to enhanced heat transfer, cooling mechanisms, thermal extrusion processes, and applications in cancer treatment, particularly in addressing brain tumors. The coupled ordinary differential equations (ODEs) are gained from governing partial differential equations (PDEs) by applying sufficient transformations. Then the ODEs of a nonlinear nature, along with boundary conditions, are solved through bvp4c, a built-in MATLAB program. A good agreement has been found in comparing the present study with already published papers. Numerical values for skin friction, mass transfer, and heat transfer are shown through a table against involved physical parameters, especially for both injection $(S<0)$ and suction $(S>0)$ cases, by varying the values of unsteadiness parameter A and Weissenberg number $W_e$. The effects of the physical parameters on velocity, temperature, and mass profile are graphically depicted and illustrated minutely. It is noted that both the magnetic and Williamson parameters cause the thickness of the boundary layer to be reduced. It can be deduced from these findings that the rate of heat transfer over the surface of the plate decreases as the unsteadiness parameter increases. Furthermore, it is observed that an increase in the parameters of thermophoresis and Brownian motion leads to a higher temperature of the nanofluid.

This investigation aims to examine the resolution of the generalized nonlinear time fractional Harry Dym $(𝔾\mathbb{N}𝕋𝔽ℍ𝔻)$ equation through a combined application of analytical and numerical methodologies. The primary objective is to scrutinize the equation’s behavior and present proficient methodologies for its resolution. The Khater II analytical technique and numerical frameworks, specifically the Cubic-B-spline, Quantic-B-spline, and Septic-B-spline schemes, are proposed for this purpose. The outcomes of this inquiry yield substantial revelations regarding the characteristics of $𝔾\mathbb{N}𝕋𝔽ℍ𝔻$ equation. Both the analytical approach and numerical schemes demonstrate their efficacy in yielding precise solutions. These findings carry noteworthy implications across various disciplines, encompassing physics, mathematics, and engineering. The investigated model appears in plasma physics research on soliton theory and nonlinear waves. Soliton waves, which keep their shape and velocity while propagating, are found in plasma physics and other domains. In plasma environments, the Harry Dym equation describes these solitons and their behavior. Solitons are essential for understanding plasma dynamics, including nonlinear waves and structures. They help comprehend plasma dynamics, wave interactions, and other nonlinear processes. The principal deductions drawn from this study underscore the effectiveness and viability of the proposed techniques in resolving the $𝔾\mathbb{N}𝕋𝔽ℍ𝔻$ equation. This research introduces innovative contributions in terms of insights and methodologies pertinent to analogous nonlinear fractional equations. Its scope encompasses nonlinear dynamics, fractional calculus, and numerical analysis.

In recent days, entropy generation has attracted the attention of several researchers due to its applications in manufacturing electronic devices, heat exchangers, conservation of energy, and generation of power. Further, activation energy is an essential requirement in automobile and chemical industries, nuclear reactors, and so on. This paper investigation aims to examine the entropy generation and the mass and energy transfer in the magneto-hydro dynamic movement of convective Carreau-Yasuda nano liquid past a porous stretching sheet with the consequences of activation energy, energy source, and binary chemical reaction. Also, the analysis of the impact of viscous and Joule dissipation in the presence of suction/injection into the Buongiorno model is an essential objective of this study. By introducing a similarity variable, the partial differential equations are altered into a system of ordinary differential equations. Numerical solutions to the modified equations are determined by utilizing a BVP5C MATLAB package. The findings are presented visually for several relevant flow characteristics and explained carefully. The thermophoresis parameter and activation energy parameter optimize the concentration of nanoparticles. These outcomes further indicate that as the larger Brinkmann and permeability parameters the entropy generation is broadened. It is discovered that an augmentation in thermal and solutal Grashof numbers is associated with greater velocity distribution.

The dynamical behavior of the capacitively coupled Ar plasma driven by four frequencies (54, 80, 94 and 100MHz) at fixed pressure are simulated by the particle-in-cell/Monte-Carlo collisions (PIC/MCC) model based on the electromagnetic field. The magnetic field is generated by plasma current itself. The results show that the electron density, charge density, and electron temperature increase with the frequency increase when radio frequency (RF) power is 40W. The electron heating rate and argon ion heating rate near the sheath increase with the frequency increase. The high-energy electron density ($>30$ eV) varies nonlinearly with the frequency increase. The high-energy electron density is highest at 80MHz among the four frequencies. The electron density, charge density, and high-energy electron density increase with RF power (30, 45, 60, and 75W) increase at 80MHz. The electron temperature decreases with RF power increase at 80MHz. The electron heating rate and argon ion heating rate near the sheath have no change with RF power increase at 80MHz. The electron energy probability distributions (EEPF) show that the number of high-energy electrons ($>30$ eV) is highest at 80MHz. The reason may be the electron resonant heating that occurs in the plasma when the electron cyclotron frequency equals source frequency at 80MHz. The electron dynamics of capacitively coupled plasma is important for microelectronics etching and membrane deposition.

The optoelectronic properties of non-metal (B, N, O, C, F) doped and biaxial tensile strain in the x–y direction of O-doped and N-doped ZrSe₂, including energy band structure, density of states, dielectric function, and absorption coefficients, have been calculated by a first-principles approach based on density-functional theory. It is shown that the doped system has a low formation energy, indicating that the structure can exist stably. The B, C, and N atom-doped systems show impurity energy levels near the Fermi energy level, narrowing the bandgap, enhancing the electron transport ability, and increasing the electrical conductivity. Biaxial stretching was applied to the ZrSe₂ structure before and after O and N doping, and it was found that the stability of the ZrSe₂, Zr₉Se${}_{17}$O${}_{1,}$ and Zr₉Se${}_{17}$N₁ structures was found to decrease gradually with increasing strain. The energy bandwidth of the doped system in the Zr₉Se${}_{17}$ O₁system at a tensile strain of 4% is a maximum of 0.924eV; from the density of states, it is found that there is a very obvious orbital hybridization of Se-4p and Zr-d. The doped system has the largest effect on the dielectric function at 6% tensile strain and on the absorption coefficient at 8%. In the Zr₉Se${}_{17}$N₁ system, stretching 8% energy bandwidth is a maximum of 0.788eV, the tensile strain of 8% has the greatest effect on the dielectric function, and a tensile strain of 6% has the most significant effect on the absorption coefficient.

The combination of a microcavity and a microsphere has been proposed in this work to manipulate light in terms of emission wavelength and propagation direction. A microcavity with a layer of molecular photoswitch between two one-dimensional photonic crystals of polyvinyl carbazole and cellulose acetate has been designed. To tune the microcavity, the molecular photoswitch has been excited taking into account its cyclization upon irradiation at 313nm and its cycloreversion at 450nm. In this way, the emission peak of the microcavity switches from 508.5nm to 525nm. A polystyrene microsphere with a radius of 1$\mu$m is placed near the microcavity. With the detector at an angle of 8°, the emission at 525nm is 1.73 times higher with respect to the emission at 508.5nm, while at 10.8°, the emission at 508.5nm is 1.45 times higher with respect to the emission at 525nm. The value of these findings is that they offer the experimentalists a ready means to compare the optical data of these types of composites with theory.

The electronic transport properties of the bilayer graphene double layer (BLGDL) system at $T=0$K using the Boltzmann transport equation are reported here. The conductivity of the BLGDL system has been calculated with varying parameters as relative carrier concentration ${(n}^{(c)}/n^{(CI)})$, short-range (point defect) and long-range (Coulomb charge) impurity concentration, relative dielectric constant $({\epsilon }_r)$ and interlayer distance $(d)$. The maximum conductivity has been achieved in the absence of short-range impurity. The short-range impurity plays a non-trivial meaningful role in high dielectric and high carrier concentration regimes and limits the conductivity. For higher ${\epsilon }_r$ and higher $n^{(c)}/n^{(CI)}$ values, the nature of the conductivity curve turns out to be of a sublinear nature, while in all other cases, it shows a superlinear trend. Suitable selection of relative dielectric constants, relative carrier concentration and interlayer distance helps to improve the conductivity of the BLGDL system. If the dielectric constant of the spacer is higher than the substrate material, the thickness of the spacer material helps remarkably in enhancing conductivity. Moreover, a comparison of BLGDL with our previously reported MLG–MLG double layer graphene system (DLGS) confirms that higher conductivity is achieved in the case of BLG–BLG system compared to DLGS.

This research concerns examining the non-Newtonian blood flow behavior through an artery of elliptic cross-section, affected by several stenoses. The Rabinowitsch fluid model is used to investigate the non-Newtonian behavior of the blood for uniform and nonuniform shapes of stenosis. The mathematical equations have been converted into a dimensionless form, and their nonlinearity is reduced by applying the assumptions of mild stenosis. The resulting differential equations are solved by using analytical techniques. A new polynomial of degree eight is introduced to complete the solutions of mathematical equations. The entropy generation is studied mathematically to analyze the irreversibility effects. The detailed graphical examination delineates the physical aspects of mathematical results. The flow velocity is higher for uniform shape than for nonuniform stenosis. The rising percentage of stenosis significantly enhances the flow velocity of the stenotic region. The entropy is enormous near the stenotic wall and has small values near the centerline, which assures the smooth flow in this region. Further, the streamlines are plotted to find the position of stenosis and assess the flow nature for the growing height of stenosis and rising flow rate.

A series of Bi${}_{0.8}$Ba${}_{0.2}$Fe${}_{1-x}$Co_xO₃ ($x=0.00$, 0.05, 0.10, and 0.15) samples were synthesized using the tartaric acid modified sol–gel method. The crystal structure of the prepared samples was analyzed by XRD, and the samples co-doped with Ba and Co were all rhombohedral distorted structures with the R3c space group. With an increase in the doping amount, a reduction in lattice parameters was observed along with crystallite sizes consistently being below 62nm. Mössbauer spectral analysis at room temperature reveals a good fit with two sextets and a doublet, all attributed to the Fe${}^{3+}$ state. This suggests that the charge balance within the samples is maintained through the generation of oxygen vacancies in the system. The hysteresis loops of all samples revealed the weak ferromagnetic of the Co-doped Bi${}_{0.8}$Ba${}_{0.2}$FeO₃ nanoparticles. With the increase in Co doping, the magnetic parameters such as saturation magnetization and coercive field significantly improved.

The structural, electronic, elastic, thermoelectric and optical properties of CeBO₃ (B = Be, Mg) oxide perovskites were investigated using density functional theory. Exchange and correlation effects were addressed through the GGA approximation and the TB-mBJ potential. Thermodynamic stability was confirmed by assessing cohesive energy and formation enthalpy. The band structures reveal a semiconductor nature with a moderate indirect band gap of 0.73 (CeBeO₃) and 0.51 (CeMgO₃). The TB-mBJ approximation has enhanced the gap value with a 55% approaching rate. These compounds exhibited a rigid and elastically anisotropic behavior with chemical bonds manifesting as a mixture of metallic and covalent types. The CeBeO₃ displayed ductility while CeMgO₃ exhibited brittleness. The optical examination suggests that these oxides exhibit activity across a broad range of the electromagnetic spectrum. Their strong reflectivity in the near-infrared region was particularly noteworthy suggesting potential use as effective shields in this domain. The replacement of beryllium with a magnesium atom enhanced thermoelectric performance by reducing thermal conductivity and increasing the merit factor. Based on the obtained results, the semiconductor perovskites CeBeO₃ and CeMgO₃ hold promise for efficient applications in optical and thermoelectric devices.