International Journal of Modern Physics B

In this paper, the formation and broadening mechanism of the low-frequency bandgap are revealed by designing a type of nonlinear acoustic metamaterial (NAM) with gaps. The mechanism of the chaotic evolution through the harmonic coupling for the NAM structure is revealed in detail, which can effectively change spectral characteristics in the bifurcation sequence, and finally, lead to a low frequency and chaos. Then, a low-frequency broadband within the NAM structures with gaps is obtained by the finite element method (FEM) due to the mechanism of chaos. Most importantly, the width of the bandgap can be successfully enlarged by adjusting the small gap, because the energy of the elastic wave can be greatly decreased or redistributed with the system going from periodic motion to doubling bifurcation. This mechanism for achieving a low-frequency bandgap overcomes the shortcomings both in the traditional local resonance with too large additional mass and in the inertial amplification structures with narrow bandgaps. Therefore, this idea of achieving a low-frequency bandgap has great theoretical significance for controlling low-frequency sound waves.

With the increased requirement of heat dissipation in the microelectronics field, the study of Flat plate Micro-Heat Pipe (FMHP) has become a hot topic. In this work, by analyzing the characteristics of the gas–liquid two-phase flow cycle within the FMHP, a Multi-Layer structured wick FMHP (MLHP) was prepared and used to improve the heat dissipation efficiency of microelectronic devices. The performance test system was set upto measure the heat transfer performance of the MLHP at different thermal powers and different liquid filling rates. The experimental results show that the MLHP of 150% filling rate can operate stably under 22 W thermal power, and it has an operating thermal resistance of 0.44${}^{\circ }$C/W. The liquid filling rate has a significant effect on the thermal performance of the MLHP. Around the suitable filling rate, the MLHP has sufficient working fluid inside and low resistance to vapor flow. Under the high thermal power, the advantages are more significant.

In this paper, a dual Riccati-type pseudo-potential formulation is introduced for a modified AKNS system (MAKNS) and infinite towers of novel anomalous conservation laws are uncovered. In addition, infinite towers of exact nonlocal conservation laws are uncovered in a linear formulation of the system. It is shown that certain modifications of the nonlinear Schrödinger model (MNLS) can be obtained through a reduction process starting from the MAKNS model. So, the novel infinite sets of quasi-conservation laws and related anomalous charges are constructed by an unified and rigorous approach based on the Riccati-type pseudo-potential method, for the standard NLS and modified MNLS cases, respectively. The nonlocal properties, the complete list of towers of infinite number of anomalous charges and the (nonlocal) exact conservation laws of the quasi-integrable systems, such as the deformed Bullough–Dodd, Toda, KdV and SUSY sine-Gordon systems, can be studied in the framework presented in this paper. Our results may find many applications since the AKNS-type system arises in several branches of nonlinear physics such as Bose–Einstein condensation, superconductivity and soliton turbulence.

The experimental data of the electrical conductivity $\sigma (T)$ and the Seebeck coefficient $S(T)$ in the temperature range from 2 K to 950 K, together with those of the Hall coefficient $R_H(T)$ in the temperature range from 2 K to 300 K, on the polycrystalline sample of $p$-type ScNiSb reported by Ciesielski et al. [Phys. Rev. Appl. 14, 054046 (2020)] have been critically analyzed with including both nearest-neighbor and Mott variable-range hopping (VRH) conduction. Through the simultaneous fits to the experimental data of $\sigma (T)$, $S(T)$ and $R_H(T)$, various transport parameters such as the bandgap energy, the effective masses of holes and electrons, and the electron-to-hole mobility ratio, are deduced together with the ionization energy and the concentration of the acceptor level. It is shown that nearest-neighbor hopping (NNH) conduction exhibits a significant effect on the Seebeck coefficient at low temperatures while VRH conduction has an only small effect on it. Contrary to the speculation by Ciesielski et al., the electron mobility is proved to be lower than the hole mobility.

Following to the Weil method, we generalize the Heisenberg–Robertson uncertainty relation for arbitrary two operators. Consideration is made in spherical coordinates, where the distant variable $r$ is restricted from one side, $0\le r<\infty$. By this reason, accounting of suitable boundary condition at the origin for radial wavefunctions and operators is necessary. Therefore, there arise extra surface terms in comparison with traditional approaches. These extra terms are calculated for various solvable potentials and their influence is investigated. At last, the time–energy uncertainty relations are also analyzed. Some differences between our approach and that, in which a direct product for separate variances were considered, are discussed.

We aimed to evaluate dosimetrically the effect of 6 MV, 10 MV and dual 6 and 10 MV photon beam energies on the liver of most cancers using steep and shoot IMRT methods, and we investigate a few important parameters, including dose, conformity index (CI) and homogeneity index (HI). The beams were arranged based on different angles. The same optimization constraints were applied for each energy planning and all other parameters, such as number of beams and beam angles, were kept constant.

The dose-volume histograms (DVHs) for the 6 MV, 10 MV and dual energy plans were compared for the planning target volume (PTV) and organs at risk (OAR). Twenty-eight cases ($n=28$) of liver SBRT patients formerly handled the use of steep and shoot IMRT techniques. Three plans with identical beam geometries were created using 6 MV, 10 MV and dual energy. In the central axis, the powerful intensity from each beam was calculated, and the values were averaged.

Based on the first-principles density-functional theory, the structural, electronic, elastic and dielectric properties of RbLi₂(NH${}_2{)}_3$, LiH and LiNH₂ are calculated. We have analyzed the bond information in detail, where the atom Li in crystal is represented in ionic characteristics mostly. The small covalent bond behaviors are also captured between atom Li and others. The ionic characteristics with tiny covalent bonds are obviously beneficial to electrons for storage capacity and transferring. The mechanical properties of three crystals reveal that LiH has a strong resistance to deformation. It is predicted that LiH has a long service life as a battery in terms of deformation. The dielectric constant reveals that LiH has a better storage capacity than that of LiNH₂. Additionally, LiH has low formation energy, where the harder substance is, the easier formation is.

In this paper, on the basis of constructing a new shift operator $S$ and choosing the Grover coin $G$ as coin operator $C$, we get the standard evolution operator $U$ on cycles. Using $U$, we not only got the analytical expression of wavefunction ${\psi }_{s,j}$, but also obtained the conclusion that the limit distribution $\pi (\nu )$ of $N$, which is not uniform distribution, regardless of $N$ is odd or even.

The time-fractional and space distributed-order diffusion equation with a singularity at the initial time is investigated in this paper. For the solution of this equation, we propose a new difference scheme on a graded mesh. The theoretical underpinning for the suggested procedure is presented, which includes the stability and convergence of the difference scheme. Furthermore, the difference strategy proves to be unconditionally stable in this research. Additionally, we demonstrate that the difference technique is convergent and that the temporal convergence rate is faster than when a uniform mesh uses. Finally, a test example is provided to ensure that the theoretical analysis is accurate.

Solar cells convert electricity from the solar spectrum to more than 60%. Researchers focused on this promising field because of the most demanding renewable source of electrical energy. Based on the demand, we focused our study on bismuth-doped tin chalcogenide materials for the optoelectronic and solar cell applications. The effect of bismuth concentration on structural, electronic, thermodynamic and optical properties of Sn${}_{0.75}$Bi${}_{0.25}$Te and Sn${}_{0.25}$Bi${}_{0.75}$Te materials is studied based on density functional theory (DFT). Generalized gradient approximation (GGA) was proposed to calculate structural parameters, density of states and band structure. Here the lattice parameter increases when increasing bismuth concentration. The parent binary SnTe is in semiconducting behavior with a narrow direct bandgap of 0.234 eV (L-L). From the calculated thermal and optical results, the Gruneisen parameter is maximum for Sn${}_{0.25}$Bi${}_{0.75}$Te and Debye temperature is maximum for Sn${}_{0.75}$Bi${}_{0.25}$Te. The studied materials are consistent in IR, visible and UV regions and they are adorable for IR optical detectors and solar cell applications.