International Journal of Modern Physics B

The influences of different ratios of Fe and N on the structure, mechanical and electronic properties of Fe${}_x$N${}_y$ compounds were studied by using the first-principles study. Our obtained lattice parameters are in excellent agreement with the experimental data. The calculated density of the Fe${}_x$N₁ compounds increases with the Fe content, which is almost consistent with the trend of the experimental results. The elastic constants indicate that the Fe${}_x$N${}_y$ compounds are mechanically stable. The values of $B$/$G$ and Poisson’s ratio indicate that the Fe${}_x$N${}_y$ compounds exhibit ductile manner. As Fe content increases, $B$/$G$ and Poisson’s ratios decrease monotonically. In particular, Fe₄N₁ has the highest hardness among all the considered Fe${}_x$N${}_y$ compounds. The obtained density of states shows that Fe${}_x$N${}_y$ is metallic in nature. The peak of the state density becomes sharper with the increase of N content, indicating that the localization of these alloys is enhanced. Among the Fe${}_x$N${}_y$ compounds, Fe₁N₁ has been found to be the most stable with respect to the band filling theory calculation.

In order to solve the low efficiency of public opinion influence analysis of social media, a new public opinion influence algorithm K-adaboost has been proposed in this paper according to adaboost and K-means algorithms. We first group the training samples and calculate the clustering center of all types of users in the group using the K-means algorithm, and then train the weak classifier of public opinion data and confirm the influence of public opinion on all types of users using the adaboost algorithm, so as to get the total influence of public opinions. Finally, we compare and analyze the performance of K-adaboost, K-means and adaboost algorithms through simulation experiments. The results show that K-adaboost has good adaptability in convergence time and accuracy.

Two-dimensional material-based photodetectors (PDs) show great potential owing to unique optoelectronic characteristics and attract much attention in research. However, poor absorption of two-dimensional material remains a vital restriction. Responsivity improvement by applying Au nanoparticles (NPs) through surface plasmon (SP) is studied both in theory and simulation. The effect of size and NPs distribution density is analyzed concerning absorption promotion and fabrication feasibility. Both absorption spectrum and inner electric field are studied. A novel face-to-face PD is proposed that performs better in visible range. The results can be helpful in two-dimensional material PD design and fabrication where high responsivity is required.

In this paper, a hollow core photonic crystal fiber (PCF)-based THz chemicals sensor has been presented. Hexagonal shaped hollow core and symmetrical hexagonal air lattices have been used in the cladding section to construct the PCF geometry. The developed PCF-based chemical sensor yields high performance in ethanol, methanol, water and benzene detection in targeted liquid samples in the THz regime, which is nearly 99% at 3 THz. Additionally, it reveals very negligible losses in both polarization modes. In addition, it renders significant improvement in different sensing properties like effective area, effective refractive index, numerical aperture (NA), nonlinear coefficient, spot size and beam divergences because of strategic geometrical arrangements. The performance of the proposed PCF sensor is numerically investigated and designed by COMSOL software v.5.3a. Fabrication feasibility of developed geometry is also stated here.

This study refers to the synthesis of new advanced preformed particle gels (PPGs) based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS), Polyvinyl Pirrolidone (PVP) and bentonite clay. For the synthesis, $\mathrm{\text{N}}$, ${\mathrm{\text{N}}}^{\prime }$-methylenebisacrylamide was used as crosslinker and ammonium persulphate as initiator. As a consequence of the inclusion of clay into the polymer matrix and the intercalation of AMPS between the layers as well as the presence of hydrophilic interactions occurring between partners, the final PPGs possessed greater swelling degrees, slower de-swelling process, high thermal stability and enhanced mechanical properties in comparison with pure PPG.

We propose a novel scheme for faithful bidirectional quantum teleportation (BQT) in which Alice can transmit an unknown N-qubit entangled state to Bob and at the same time Bob can transmit an unknown M-qubit entangled state to Alice by using a four-qubit entangled G-state as a quantum channel. We also propose a new scheme for cyclic QT of multi-qubit entangled states by using two G-states as a quantum channel. The advantage of our schemes is that it seems to be much simpler and requires reduced number of qubits in quantum channel as compared with the other proposed schemes.

Epidemics are affected by the connectivity of nodes in networks in addition to the cooperation of infection transmission. We investigate quantitatively the effects of node connectivity on transmission dynamics by comparing epidemic diffusion in null models with gradual connection strength. Results show that: (1) the inhomogeneity of network connectivity accelerates the spreading of epidemics, this phenomenon is more significant in the early stage of propagation; (2) the enhancement of connectivity of homogenous nodes restrains epidemic spreading, and the spreading speed correlates negatively with connection strength; (3) the spreading speed of epidemics does not change linearly with the strength of rich-club property, which means that the connectivity among hub nodes does not appreciably affect disease diffusion.

As an ionic electroactive polymer, ionic polymer metal composite (IPMC) has unique advantages and is widely used in various fields. However, the output force of IPMC is small, which further limits the application of IPMC. In this study, the Nafion520cs were selected as the preparation solution, and three ion-exchange polymer membranes (IEPMs) with different thicknesses (158, 256 and 383 $\mu$m) were designed and prepared successfully by solution casting technique to study the output force. Then, three platinum electrodes-IPMCs (Pt-IPMCs) were fabricated using electroless plating method. The properties of Pt-IPMCs in terms of morphology, displacements and blocking forces were then evaluated under direct current voltage. The results showed that the prepared ionic membranes were uniform, transparent and flat, without accumulation or bubble. The platinum particles were preferably deposited on the surface, which promoted delivery of current through the IPMCs under the applied voltage, and improved the actuation performance. With the increase of voltage, the maximum displacement and maximum blocking force of the three IPMCs increased first and then decreased. When the voltage is 5.5 V, the maximum displacement for 158 um is 26 mm, while the maximum blocking force of 10.74 mN appears at 6.5 V for 383 um. It is necessary to select suitable thickness of IPMCs to adapt to different working environment and field, which provides a strong basis for further application of IPMCs.

In this research study, computational investigations are prepared to demonstrate the influence of the nonhomogeny magnetic source on the thermal efficiency of the convergent tube with the nanofluid flow. The major attention of our examination is to analyze the flow stream and temperature spreading on the average Nusselt number of the base fluid with Fe2O3 nanoparticles. The effects of inlet velocity and magnetic intensity on the thermal characteristics of nanofluid stream through the convergent tube are fully investigated. SIMPLEC algorithm is used for the imitation of the incompressible nanofluid flow inside the convergent tube. Our results indicate that growing Reynolds number from 50 to 100 surges heat rates up to 18% in the convergent tube because of the existence of the magnetic field in the vicinity of the tube.

Ferroliquids are made out of exceptionally tiny nanoscale particles (usually diameter 10 nanometers or less) of hematite, magnetite or some other compound comprising iron and a liquid. This is small enough for thermal agitation to scatter them equally inside a transporter liquid, and for them to contribute to general magnetic response of the liquid. The composition of the typical ferroliquid is about 5% magnetic solids, 10% surfactant and 85% carrier by volume. There are frequent applications of ferrofluids in mechanical and industrial engineering. Ferrofluids have innovative characteristics and their impact in magnetic fields prompts many fascinating applications. Albeit magnetic liquids are already utilized in certain devices they have not yet been abused to any level. It is trusted that this research communication may investigate the analyst to think of considering new uses for this entrancing material. Therefore, modeling is developed for the ferrofluid stagnation flow over a stretched surface with Ohmic heating and dissipation. The Tiwari–Das model is used for mathematical modeling of nanofluid. The nonlinear system of differential equations is first converted into first order and then tackled through the built-in-Shooting method. The impact of the different pertinent flow parameters is discussed on the velocity, temperature, Nusselt number and skin friction coefficient through the various plots and tables.

The simulation and process optimization for laser marking of submillimetre rasterizing 2D code on stainless steel are investigated. For 50CrVA stainless steel, the temperature field of material during laser marking is obtained by numerical modeling. The results show that temperature change in the depth direction and oxidation degree of laser radiation region are the fundamental reasons for the contrast of 2D code, but the temperature change occurs in the radius direction for the print growth. The threshold of laser average power and $Q$ frequency for an identifiable submillimetre 2D code are, respectively, 3.0 W and 100 KHz, which matches the simulation well within normal operating conditions. It is also found that an increase of the pulses number effectively improves the contrast and the appearance consistency of modules in DM code. Besides, corrosion tests show that the corrosion resistance of submillimetre 2D code is greatly improved by covering a layer of transparent polyurethane coating. Finally, a sample of submillimetre 2D code marked on cylindrical tool with diameter of 1 mm is obtained. In conclusion, the method could obtain submillimetre code with high reading quality and corrosion resistance by minimizing the characteristic edge over-burn effects, which provides theoretical basis and experimental method for identification of small parts.

Due to the outstanding performance of resistance random access memory (RRAM) in the memory field, the study of resistive switching (RS) phenomena has become extremely noticeable in the recent years. The mechanism of metal conductive filamentary RRAM is already clear, but the conditions of the RS are still unclear. Therefore, this paper aims to explore the conditions for the occurrence of resistive, using a new RS structure called Electrolyte-Oxide-Semiconductor (EOS). This structure is based on the formation of metal conductive filament and exhibits the unipolar switching characteristics. Due to the formation or rupture of the conductive filaments, this device exhibits different resistance states. A series model of electrolyte and conductive filaments is used to explain the IV curve of this device. Compared with the device using a metal active electrode, the active electrode of this device is originally ionized. Therefore, it would be a better tool to explore the mechanism of ion migration and the formation of conductive filaments. Materials screening of metal in RRAM would also be more efficient.

In this work, we consider the (2+1)-dimensional Maccari’s system, which is frequently introduced to describe the motion of the solitary waves. Abundant lump, line rogue wave, and dipole-type rogue wave are constructed by taking the ansatz method. Furthermore, the mixed interaction solutions between lump and multi-stripe solitons (such as fission and fusion) are obtained in combining rational function with exponential function. In particular, an interesting result is obtained: a rogue wave is excited from multi-stripe solitons.

Performance improvement of topological similarity-based link prediction models becomes an important research in complex networks. In the models based on node influence, researchers mainly consider the roles of endpoints or neighbors. Through investigations, we find that an endpoint with large influence has many neighbors. Meanwhile, the neighbors connect with more nodes besides endpoint, meaning that the endpoint can transmit extensive influence by the powerful combination of itself and neighbors. In addition, we evaluate the node influence by degree because the degree represents the number of neighbors accurately. In this paper, through focusing on the degree of endpoints and neighbors, we propose the powerful combination of endpoints and neighbors (PCEN) model. Experiments on twelve real network datasets demonstrate that the proposed model has better prediction performances than the traditional models.