International Journal of Modern Physics B

The structure and properties of the nanosized ${\mathrm{\text{CeO}}}_2$ under high pressure have been investigated by synchrotron X-ray diffraction in the diamond anvil cell combined with the first-principle methods based on density functional theory. The experimental data demonstrate that nanosized ${\mathrm{\text{CeO}}}_2$ is highly stable upto 31.3 GPa and bulk modulus is $213\pm 3$ GPa. The calculated results by $\mathrm{\text{LDA}}+\mathrm{\text{U}}$ indicate that ${\mathrm{\text{CeO}}}_2$ undergoes structural transition from cubic fluorite-type structure to orthorhombic $\alpha$-${\mathrm{\text{PbCl}}}_2$-type structure at 20 GPa. The indirect band gap $(\mathrm{\text{R}}\to \mathrm{\text{G}})$ is 1.89 eV and increases with the increasing pressure while it suddenly reduces to 1.62 eV at transition pressure. The transition pressure calculated by GGA is 40.3 GPa.

This study is aimed for the analysis of different designs for sensing low magnitude forces which lies in the micro-Newton range and suitable for biomimetic microbotics. For this, a flexible and high sensitive Micro Electro Mechanical System (MEMS) based Force sensor using piezoresistive sensing mechanism has been analyzed. Design analysis is carried out for sensitivity enhancement on microcantilever by incorporating various combinations of stress concentrated regions (SCR) and their respective arrays. The materials under consideration for sensor are polysilicon piezoresistors and Polydimethylsiloxane (PDMS) microcantilever. For design analysis, the designing and simulation work is assessed using Finite Element Analysis approach in COMSOL Multiphysics 5.3a software. The results revealed that the electrical sensitivity of 1.62 mV/$\mu$N within (0–100) $\mu$N operating range is achieved for microcantilever with rectangular SCR with square SCR array. This operating range has many applications in microbotic field such as sensing tactile movements. Hence, MEMS Force sensor for low magnitude forces has been designed with high sensitivity and flexibility.

Motivated by recent developments in experimental studies of Bose–Fermi mixtures, we investigate monopole oscillation dynamics of Bose–Fermi mixtures in a three-dimensional (3D) optical lattice and an external isotropic harmonic trap potential. We use dynamical Gutzwiller approximation and calculate time dependence of the average spatial extent of particles in a coexisting phase where superfluid bosons and metal fermions coexist. With the trap potential, the bosons concentrate at and around the center of the potential and the fermions surround the bosons. They begin to demonstrate monopole oscillations when the trap potentials are suddenly changed to the ones with smaller curvature. In particular, the correlation between the oscillations of the bosons and fermions is different depending on the condition of the initial confinement. We also show the case where only one of the two trap potentials is changed.

A variety of electric components can be used to bridge connection to the nonlinear circuits, and continuous pumping and consumption of energy are critical for voltage balance between the output end. The realization and stability of synchronization are mainly dependent on the physical properties of coupling channel, which can be built by using different electric components such as resistor, capacitor, induction coil and even memristor. In this paper, a memristive nonlinear circuit developed from Chua circuit is presented for investigation of synchronization, and capacitor, induction coil are jointed with resistor for building artificial synapse which connects one output of two identical memristive circuits. The capacitance and inductance of the coupling channel are carefully adjusted with slight step increase to estimate the threshold of coupling intensity supporting complete synchronization. As a result, the saturation gain method applied to realize the synchronization between chaotic circuits and physical mechanism is presented.

Recently, strong coupling dominating dissipative and decoherence effects between the atom and a quantum cavity has been investigated experimentally. In this paper, we study the entanglement dynamics of two two-level atoms coupling to a quantum cavity where each mirror is formed by a chain of atoms trapped near a one-dimensional waveguide. We consider the effects of both Markovian dynamics and non-Markovian dynamics on the entanglement evolution of the two central atoms. Our results show that the steady entanglement can be generated between the two central atoms whether the system is under the Markov regime or non-Markov regime when the number of atoms of the atomic mirrors is finite. When the number of the atomic mirrors is large enough, the entanglement of two central atoms takes oscillating behavior without a stable value. The effect of detuning and dissipation on entanglement dynamics is also discussed and the results imply that the detuning plays an important role in improving the entanglement amplitude.

Terrorist network may be defined as collection of suspected terrorist nodes which may function in disguise towards accomplishing a terrorist activity. They use extensive communication channel for sharing crucial information. Terrorist network analysis is highly efficacious for intelligence analysis and deriving useful conclusions from available data. Computer Science and Network analysis act as pertinent fields for the study and graphical interpretation of these networks. In this paper, we examine the 26/11 Mumbai attack terrorist network dataset and employ the ELECTRE method for identification of key node in the terrorist network. ELECTRE is an effective multi-criteria decision-making model. It provides a framework for structuring a decision problem integrates the quantitative and qualitative factors of the problem and facilitates easy computation. From the 26/11 Mumbai attack dataset of terrorist network, we have determined that out of several terrorists in the network “Wassi” was the momentous and mastermind of all. The proposed work also demonstrates improvement of result in terms of concurrence, generalization accuracy and genuineness. Based on the solution of ELECTRE framework, it is resolved that the obtained (terrorist) nodes will step up the work of law enforcement agencies and enable them to confine their focus on important members of the terrorist network. Identification of key terrorist is highly important for developing long-term strategies to counter forthcoming terrorist attacks. It can be better implemented during the development of smart city especially for India.

In this work, to investigate the role of the third body in the fretting behavior of 690 alloy, the fretting capabilities of 690 alloy against 405 stainless steel have been performed under various experimental conditions. The testing normal force and temperature varied from 10 N to 40 N and from room-temperature (RT) to $285^{\circ }$C, respectively, at 5 Hz and 200 $\mu$m. The results demonstrated that the profile shape of wear scar was dependent on the action of the wear particles. Three typical profile shapes were examined in this work: “U” shape, “W” shape and “M” shape. The balance of the formation and ejection of wear particles led to a steady value of the coefficient of friction (COF) and friction energy.

The solitons and other solutions illustrate nondiffractive and nondispersive spatio-temporal localized packets of wave propagating in the media of optical Kerr. In this paper, solitons, elliptic function and other solutions of dimensionless time-dependent paraxial wave model are constructed via employing three mathematical techniques, namely, the improved simple equation technique, $exp(-\mathrm{\Phi }(\zeta ))$-expansion technique and modified extended direct algebraic technique. These wave solutions have key applications and help to understand the physical phenomena of this wave model. By giving appropriate parameter values, different types of solitons structures can be depicted graphically. Several precise solutions and computations have proved the straightforwardness, consistency and power of the these techniques.

This paper implements bifurcation method and the rational sine-Gordon expansion method to investigate the dynamical behavior of traveling wave solutions of a 2D complex Ginzburg–Landau equation. By varying the parameters, we obtained traveling wave solutions including the periodic wave solutions, solitary wave solution, kink and anti-kink wave solution and in addition by using the rational sine-Gordon expansion method, we determined bright and dark soliton which have a great contribution in the long distance telecommunication system.

We investigate the spin excitations at the (001) stepped surface in semi-infinite antiferromagnetic monoxide cubic rocksalt structure of the type MO, made up from compounds of metal cations M${}^{2+}$ and oxygen anions O${}^{2-}$. At the surface, of semi-infinite monoxide lattices, the translation symmetry along the direction normal to surface zone is broken. Therefore, significant changes of spin dynamics and magnetic properties are expected at the surface in question. The dependence on properties comes from the geometrical arrangement of the chemical species present at the surface, leading to appearing localized antiferromagnetic spin modes. The spin excitations and the amplitudes of precession due to variations in exchange and superexchange parameters generated by the stepped surface zone are simulated and analyzed, for different cases that can be considered, from softening to hardening effects. The technical formalism of matching method, associated to Green functions, is employed to determine the magnonic densities of states, for the spin components of the individual sites that constitute a complete representation of the stepped surface domain boundaries. Our results shown that the calculated localized spin modes are sensitive to the magnetic coupling between different spin sites at the surface. The simulated cases yield criteria under certain experimental conditions, as regards the interpretation of the measurements of the magnetic interactions in the surface zone and its boundaries. However, for a given material, the spin surfaces corresponding to different orientations are not equivalents and, in particular, they do not have the same stability.

In this study, nickel oxide nanostructured particles were produced by hydrothermal method. X-Ray diffraction (XRD) and transmission electron microscope (TEM) measurements were performed to determine the physical properties of these nanostructured particles. When XRD results are examined, it is seen that NiO nanoparticles are cubic structure. It is understood from the TEM images that these particles are nanostructured. The photocatalytic activities of nanostructured particles were investigated. This examination was carried out by using methylene and methyl blue dyes under the xenon lamp. It has been observed that the photocatalytic degradation rates are high. It was found that the degradation of NiO nanostructured particles on methylene blue was about 59%, the decomposition on methylene blue added H₂O₂ was about 96% and the degradation on methyl blue was about 92%.

Theoretical calculations on the effects of different Sr-doped ratios and oxygen vacancy concentrations on the magnetic mechanism of anatase TiO₂ are rarely reported. For this problem, generalized gradient approximation (GGA) plane wave ultra-soft pseudopotential $+$U based on the spin density functional theory framework was adopted in this work. The effect of different Sr doping ratios and O vacancy concentrations on the magnetic properties of anatase TiO₂ was studied by first principles. Results show that Sr replaces Ti and O vacancies at different Sr:V${}_{\mathrm{\text{O}}}$ ratios (1:0, 1:1, 1:2, 2:1 and 2:2), the doping system is magnetic when the Sr:V${}_{\mathrm{\text{O}}}$ ratio is 1:2. The systems with Sr${}_{\mathrm{\text{i}}}$:V${}_{\mathrm{\text{O}}}$ ratios of 1:0 and 2:1 are nonmagnetic, whereas those with 1:1, 1:2, and 2:2 Sr${}_{\mathrm{\text{i}}}$:V${}_{\mathrm{\text{O}}}$ ratios are magnetic. Regardless of whether or not Sr replaces Ti and O vacancies or interstitial Sr and O vacancies in different ratios of anatase TiO₂, the effect of magnetic switching can be achieved by adjusting the concentration. In this study, the largest magnetic moment of Ti${}_{16}$Sr${}_{\mathrm{\text{i2}}}$O${}_{30}$ system is obtained at Sr${}_{\mathrm{\text{i}}}$:V${}_{\mathrm{\text{O}}}$ ratio of 2:2. The Curie temperature of the doping system is above room-temperature, and the doping system produces 100% electron spin polarizability and is half-metallized. These features are valuable to the design and preparation of novel dilute magnetic semiconductors with spin-electron injection sources. The main magnetic sources of the Ti${}_{16}$Sr${}_{\mathrm{\text{i2}}}$O${}_{30}$ system are the holes generated by doped Sr and O vacancy complexes, which cause the spin polarization double exchange of Ti-3d electron orbitals and O-2p electron orbits near O vacancies. This result is consistent with the average field approximation and dual exchange mechanism theories.

A potential scheme to obtain intense harmonic spectra from X${}_2{}^{+}$ ($\mathrm{\text{X}}=\mathrm{\text{H}}$ and T) has been studied by using chirped-delay effect and half-cycle pulse. First, for the shorter pulse duration case, the main contributions of harmonic spectra of H${}_2{}^{+}$ and T${}_2{}^{+}$ are both coming from the falling part of laser field. While, for the longer pulse duration case, the rising and falling parts of laser field play the main role in harmonic spectra of H${}_2{}^{+}$ and T${}_2{}^{+}$, respectively. Second, according to the changed law of harmonic yields of H${}_2{}^{+}$ and T${}_2{}^{+}$ and by properly introducing the chirp-delay effect at some specific timing, the intense harmonic emission peak (HEP) can be obtained from both H${}_2{}^{+}$ and T${}_2{}^{+}$. Third, with the help of the half-cycle pulse, the selected HEP can be further extended, showing the intense and broad spectral continua. Finally, by Fourier transformation of some harmonics on the spectral continua, the intense attosecond pulses with durations of 35 as can be produced.

New analytical wave solutions are investigated of the fractional nonlinear $(2+1)$-dimensional Boiti–Leon–Manna–Pempinelli equation to explain more physical properties of the dynamical behavior of the incompressible fluid. A new fractional definition is used through the modified Khater method to get novel solitary wave solutions of this model. The stability property of the obtained solutions is tested to show the ability of our obtained solutions in using through the physical experiments. The novelty and advantage of the proposed method are illustrated by applying to this model. Some sketches are plotted to show more about the dynamical performance of this model.

Our aim in this research work is to formulate the exact traveling and solitary wave solutions of nonlinear diffusion reaction (DR) equation with quadratic and cubic nonlinearities by implementing the new technique which is a modified mathematical method. We have investigated the density independent nonlinear diffusion equation with convective flux term. As a result, we have found a variety of new exact traveling and solitary wave solutions in the form of dark solitons, bright solitons, combined dark-bright solitons, traveling wave, periodic wave solutions and we also represent the physical structure of the obtained solutions by two- and three-dimensional graphics by using the Mathematica software. This work proves the power, reliability and fruitfulness of this new technique.

It was known that for non-Hermitian topological systems due to the non-Hermitian skin effect, the bulk-edge correspondence is broken down. In this paper, by using one-dimensional Su–Schrieffer–Heeger model and two-dimensional (deformed) Qi–Wu–Zhang model as examples, the focus is on a special type of non-Hermitian topological system without non-Hermitian skin effect — topological systems under non-Hermitian similarity transformation. In these non-Hermitian systems, the defective edge states and the breakdown of bulk-edge correspondence are discovered. To characterize the topological properties, a new type of inversion symmetry-protected topological invariant — total $Z_2$ topological invariant — has been introduced. In topological phases, defective edge states appear. With the help of the effective edge Hamiltonian, it was found that the defective edge states are protected by (generalized) chiral symmetry and thus the (singular) defective edge states are unstable against the perturbation breaking the chiral symmetry. In addition, the results are generalized to non-Hermitian topological insulators with inversion symmetry in higher dimensions. This work could help people to understand the defective edge states and the breakdown of bulk-edge correspondence for non-Hermitian topological systems.