Indian Journal of Physics最新文献

We study the phenomenon of Bose–Einstein condensation in two- and one-dimensional Dunkl–Boson gases confined within a power-law potential, employing the framework of Dunkl-deformed boson theory. Our investigation involves the calculation of particle numbers and phase transition temperatures using the Dunkl formalism. To assess the validity of our findings, we compare them with the corresponding results obtained from the standard approach. We find that the impact of the Dunkl formalism on the condensate fractions is similar in one- and two-dimensional cases. However, we see that this conclusion is not fully valid for the phase transition temperature.

The thermo-optic coefficients (TOCs), thermo-polarization coefficients (TPCs) and dn/dT, dα/dT of congruent lithium niobate LiNbO₃ / LN (mole ratio Li/Nb = 0.946) are tested within the temperature range of 293–773 K at λ = 0.4358 µm, λ = 0.6328 µm and λ = 1.15232 µm employing the point dipole approximation. The refractive indices, n_o and n_e, were first determined at these temperatures and wavelength ranges, by iterating the electronic polarizabilities of Nb⁵⁺ and O²⁺ ions. It has been found that the polarizability of Nb⁵⁺ ions drops and that of O²⁻ ions increases when temperature rises for a particular wavelength. Both Nb⁵⁺ and O²⁻ lose polarizability with increasing wavelength for a given temperature. TOCs for n_o and n_e rise as the temperature rises. The TOC rises as wavelength for n_o and n_e decreases. TPCs of O²⁻ rise in ions and temperature causes Nb⁵⁺ ions to decrease. At a particular temperature, TPCs of O²⁻ions become less while Nb⁵⁺ ions grow as wavelengths rise. Generally, it is used in potential electronic polarizabilities and thermal refraction applications.

The motion of the tri-stable oscillator can be transferred between different equilibrium points to produce a large response, which is the desire of vibration energy harvesting technology. Therefore, the vibration of the tri-stable system has been a widespread concern. However, the mechanism of the system with parametric slow excitations has not been discovered. To study this issue, we treat a novel bursting pattern in a tri-stable oscillator under slow cosinoidal excitations. The complex dynamic behaviors of bursting oscillation under single and two frequencies are presented using the fast-slow analysis method, the one-parameter bifurcation diagrams are plotted, and the bifurcation patterns associated with independent loop and closed loop are observed. Furthermore, different types of bursting oscillations induced by subcritical pitchfork/fold bifurcations are presented, and jumping phenomena and hysteresis behaviors are displayed. Moreover, the stabilities of equilibrium of the independent and closed loop positions are checked by potential energy, and the transition of different equilibrium configurations is validated by introducing the transformed phase diagram. Finally, the attraction basin of each equilibrium point is estimated via cell mapping, and the multivalued response orbits are recognized.

Introducing dynamical systems that involve a variable in the trace of the Jacobian matrix is a difficult challenge due to it is difficult to determine whether a system is dissipative or conservative. This paper introduces a new 3D chaotic nonuniformly conservative system with a variable in the trace of the Jacobian matrix through the Hamiltonian form. The proposed system is without equilibrium points (hidden attractors) and satisfies categories C and D. The system exhibits three distinct behaviors (chaotic, quasi-periodic, periodic) under the same parameters with varying initial conditions. The characteristics system are investigated through a combination of theoretical analysis and numerical simulations, including dissipative and conservative behavior, equilibrium points, bifurcation diagrams, Lyapunov exponents, and multistability. Finally, two applications are implemented: an electronic circuit and image encryption based on the proposed system. These outcomes substantiate the sufficiency and viability of this system, demonstrating its effective performance.

We report results of magnetoviscosity and magnetically induced changes in microstructural properties of a ferrofluid made of copper zinc ferrite (CuZnFe) nanoparticles. These measurements were performed by tracking thermal motion of a tracer particle and video microscopy, using a home-built microscope. It has been established that the nanoparticles align to form chain-like structures under influence of external magnetic field, which result in an anisotropy of properties in two different directions, and also a magnetic field dependency of the properties. Most ferrofluids show an isotropic nature in the absence of any external magnetic field and a field-dependent anisotropy in the presence of magnetic field. But the CuZnFe sample studied here shows an anomaly with an anisotropic behaviour even when field is zero. This is perhaps one of the first cases where such anomaly is observed. Upon application of magnetic field, the parallel and perpendicular evolve in two different trajectories. We present the measurement of viscosities, both parallel to and perpendicular to the applied field, and from therein derive microstructural properties such as elastic moduli and relaxation time. All measurements were taken at room temperature (300 K).

This work investigates a conspicuous disease of pine trees known as pine wilt disease (PWD). This disease propagates through a pine wilt nematode, a microscopical ringworm that mainly contaminates the pine trees of the Pinus genus. Its development way comprises many stages. Pine trees impacted by PWD initially show yellow-colored leaves and then turn reddish brown after some time. The pine sawyer beetles act as conveyors that transfer the pine wilt nematode. The disease in the frame of the PWD model is studied with fractal–fractional (FF) derivatives in the context of Caputo and Caputo–Fabrizio (CF) derivatives under different fractional order ({partial_{1}}) and fractal dimension ({partial_{2}}) values. Here, the fundamental characteristics of the given model are discussed. The fixed point theory’s theoretical results are interpreted for existence and uniqueness, while Ulam–Hyres (UH) stability is also presented for the given model. Further, the Caputo and CF derivative-based numerical schemes are also displayed. After analyzing the numerical simulations, it is found that the FF operator is more capable of analyzing the PWD model.

A series of novel Dy³⁺: NaGdGeO₄ phosphors were prepared by a facile high-temperature solid-phase method. Its electronic structures were investigated using first-principles based on DFT. These phosphors kept stable phase structure and displayed strongly yellow emission under the excited wavelength of 347 nm. It presented excellent thermal stability (77% of room temperature emission intensity at 416 K). In addition, some other luminescent properties like the level lifetime (338 µs), IQE (40.86%) and CCT (3179 K) were discussed respectively. These results showed it could be used as a kind of valuable yellow phosphor for LED.

The co-precipitation technique is employed for preparing ZnO/CoFe₂O₄ composites. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR) and Rietveld refinement techniques is performed to investigate the composite structure obtained after annealing. The Rietveld refinement method gives information about crystalline phases present in the sample. Rietveld analysis of X-ray diffraction results reveals the presence of two phases where phase 1 is zinc oxide with hexagonal structure, whereas phase 2 is cobalt ferrite with cubic structure. XRD shows the size of crystallites for phase 1 is 43 nm, and for phase 2 is 38 nm. FTIR peaks centered at 440–515 cm⁻¹ corresponds to M–O stretching vibrations. Dielectric properties such as ε′, ε″, Tanδ, conductivity, and electric modulus of the sample have been measured at temperature 30–300 °C and the frequency range is 1–10⁷ Hz. Dielectric parameters show dependence on frequency and temperature as well as on concentration and temperature used for synthesis of samples. Synthesized sample at temperature 400 °C and concentration 1:1 shows highest value of ε′ i.e., above 1000. To study magnetic properties VSM characterization is used. High value of ε′, Tan δ and remarkable low value of conductivity (high resistivity), retentivity (0.01–2.17 emu/g) and coercivity (34.8–213 Oe) indicate its application in high frequency devices.

In this study, we investigate the impact of inherent randomness on fire spread rates, with a particular focus on the stochastic parameter ε, representing the ratio of effective to actual fuel bulk density. By employing various probability distributions, such as the beta random distribution model ε, we explore the complex interplay between wind and slope factors in determining fire behavior. Our 3D visualizations and density plots illuminate the multidimensional nature of fire spread, emphasizing the significant role of stochastic variability in enhancing the accuracy of fire behavior models. This approach not only deepens our theoretical understanding but also provides valuable insights for improving fire management strategies.

At present, the prepared EMNZ media based on a resonance mechanism that is very sensitive to frequency, in other words, they currently only operate at point frequency or in a very narrow frequency band, which greatly limits the applications of the EMNZ media. It can be seen that broadening the operating bandwidth of EMNZ media is an urgent problem to be solved in the design of high-performance electromagnetic devices. In the paper, a novel method for broadening the resonance bandwidth for realizing EMNZ media has been proposed based on the doped ENZ media. At first, the field distribution has been analyzed theoretically in the structure of the doped ENZ media. Then, the effective permeability of the EMNZ media realized by the structure of the doped ENZ media has been rigorously calculated with different parameters of dopants. The theoretical analysis and the simulation results show that the amount of dopants in the ENZ media is increased on the premise that the above structure is equivalent to EMNZ media, which can reduce the sensitivity of the above structure to the changing frequency, thereby broadening the operating bandwidth of the EMNZ media.