Modern Physics Letters B

The impact of shape, size and temperature on elastic properties of nanomaterials is studied in this work. We have extended the melting temperature expression for nanostructures formulated by Guisbiers et al. and obtained the expression of elastic moduli and thermal expansivity for nanomaterials. An isobaric Tait equation of state is combined with Guisbiers model and the model so obtained is applied to analyze the shape, size and temperature effect on Young’s modulus and thermal expansivity in nanomaterials. The present computed results are compared with the simulated results and available experimental data. The Young’s modulus is observed to decrease as particle size is reduced while thermal expansivity increases with decrease in the size of nanomaterial. The Young’s modulus shows decrease with increase in temperature and decrement is observed maximum in spherical nanomaterials and minimum in nanofilms (NFs). Rate at which modulus is decreasing is found to increase as particle size is reduced. Good consistency of present predicted results with the available theoretical and experimental data is observed. The present calculated results are thus found consistent with the general trend of variation.

To address the problem of low accuracy of aircraft flight trajectory, a new prediction method for flight trajectory is proposed based on the quasi-Newton and mesh simplification algorithm. This method firstly proposes the calculation method of 3D aircraft flight trajectory, and simplifies the calculation process with mesh simplification algorithm. At the same time, the prediction accuracy is further improved with the quasi-Newton algorithm. At last, through the simulation experiment, we have made a deep study of the key factors influencing the prediction method. The result has shown that the method has good adaptability.

In this paper, a comb-like locally resonant phononic crystal (LRPC) with optimal structural parameters, which has good low frequency and broadband band gaps (BGs) between 20–250 Hz, is investigated numerically. With the intention of obtaining the optimal structural parameters, based on the structures with different number of the short elastic beams, 2-factor (the two key structural parameters, i.e. the width of the scatterer and the thickness of elastic beams) and 7-level numerical experiments are designed to obtain simulations data using finite element method (FEM). The functional relationships are further constructed using the response surface method (RSM) analysis, i.e. the relationship of the starting frequency of the first BG and the two factors, the terminating frequency of the second BG and the two factors, and the relationship of the total bandwidth of the first two BG and the two factors. After calculation using interior point method, the BGs of LRPC with optimal structural parameters are determined with lower and wider BGs below 250 Hz.

In this work, an attempt has been made to compare the physical properties of conductive films of Nb-doped TiO₂ deposited on Kapton polyimide, glass and silicon substrates. Thin films were deposited by radio frequency sputtering at room temperature and subsequently characterized using X-ray diffraction, X-ray photoelectron spectroscopy, UV-VIS-NIR spectroscopy and Hall Effect measurement. Structurally, the films grown on the flexible substrate exhibit more strain and had inferior crystallinity (crystallite size $\sim$13.8 nm) compared to the films deposited on glass and silicon substrates (crystallite size $\sim$27 nm). The film on glass had a resistivity value around $1.67\times 10^{-3}\mathrm{\Omega }\cdot \mathrm{\text{cm}}$ while the resistivity of the films grown on polyimide was found about five-fold higher. Furthermore, the films deposited on glass substrate showed optical transparency of $>$80% in the visible range (400–750 nm). The inferior electrical transport properties of the films grown on polyimide were correlated with the poor crystallinity and cracks induced during the annealing process. Furthermore, various possible routes have been discussed to improve crystallinity and control cracks in the films.

The network topology and the routing strategy are major factors to affect the traffic dynamics of the network. In this work, we aim to design an optimal time-varying network structure and an efficient route is allocated to each user in the network. The network topology is designed by considering addition, removal and rewiring of links. At each time instant, a new node connects with an existing node based on the degree and correlation with its neighbor. Traffic congestion is handled by rewiring of some congested links along with the removal of the anti-preferential and correlated links. Centrality plays an important role to find the most important node in the network. The more a node is central, the more it can be used for the shortest route of the user pairs and it can be congested due to a large number of data coming from its neighborhood. Therefore, routes of the users are selected such that the sum of the centrality of the nodes appearing in the user’s route is minimum. Thereafter, we analyze the network structure by using various network properties such as the clustering coefficient, centrality, average shortest path, rich club coefficient, average packet travel time and order parameter.

Silicon nanoparticles have been irradiated by neutrons up to 20 h. Free electrons and defects in the nanosilicon particles have been comparatively investigated before and after neutron irradiation using electron paramagnetic resonance (EPR) method. The neutron scattering and capture cross-section processes have been calculated for natural ${}_{14}{}^{28}\mathrm{\text{Si}}$, ${}_{14}{}^{29}\mathrm{\text{Si}}$, ${}_{14}{}^{30}\mathrm{\text{Si}}$ isotopes, which are main part of nanosilicon samples when irradiated for 20 h by epithermal neutrons. Particle size, agglomeration and other surface effects of silicon nanoparticles were studied with scanning electron microscope (SEM) before and after neutron irradiation.

Fractional calculus (FC) is a valuable tool in the modeling of many phenomena, and it has become a topic of great interest in science and engineering. This mathematical tool has proved its efficiency in modeling the intermediate anomalous behaviors observed in different physical phenomena. The Meissner–Ochsenfeld effect describes the levitation of superconductors in a nonuniform magnetic field if they are cooled below critical temperature. This paper presents analytical solutions of the fractional London equation that describes the Meissner–Ochsenfeld effect considering the Liouville–Caputo, Caputo–Fabrizio–Caputo, Atangana–Baleanu–Caputo, fractional conformable derivative in Liouville–Caputo sense and Atangana–Koca–Caputo fractional-order derivatives. Numerical simulations were obtained for different values of the fractional-order.

This paper discusses bright, dark and singular optical soliton as well as complexiton solutions to the coupled Fokas–Lenells equation (FLE) for birefringent fibers by three integration tools such as $exp(-\varphi (\chi ))$-expansion method, the first integral method and the sine-Gordon expansion method. The existence criterion of these solutions is also given.

The transport of biomolecules across bio-membranes occurs in a complex environment where the fluid on both sides of the membrane contains many inclusions. The Monte Carlo method and the hard-sphere (HS) model are used to simulate the translocation of linear polymer and ring polymer through a nanopore in a crowded environment. We compare the results of linear polymer and ring polymer and find that the ring polymer is more sensitive to the surrounding environment. Moreover, the influences of the nanopore and the inclusions to the translocation are studied and our results show that the nanopore changes the translocation time and the inclusions change the translocation tendency to the random side of the membrane. Here, the radius of gyration is described as a balance.

In this paper, we study the twist of the nematic liquid crystal molecules under the applied electric field. The dynamic equation of the twisted molecules is derived. It is proved to be a kind of sine-Gordon (SG) equation. We obtain the breather solution of the equation and confirm that the deflection angles of the twisted molecules can distribute in the form of breathers. We give the relationship between the molecular deflection angle and the breather frequency, and discuss the effect of electric field on breather shape and breather frequency.

An orthogonal state of coherent state is produced by applying an orthogonalizer related with Hermite-excited superposition operator $H_m(x{a}^{†}+ya)$. Using some technique, we cleverly deal with the normalization and discuss the nonclassical and non-Gaussian characters of the orthogonal state. The analytical expressions for the Wigner functions of the orthogonal state are derived in detail. Numerical results show that the orthogonal state will exhibit its richly nonclassical and non-Gaussian character by changing the interaction parameters.

This research pertains to classification of the heart sound using digital Phonocardiogram (PCG) signals targeted to screen for heart ailments. In this study, an existing variant of the decision tree, i.e. XgBoost has been used with unsegmented heart sound signal. The dataset provided by PhysioNet Computing in Cardiology (CinC) Challenge 2016 has been used to validate the technique proposed in this research work. The said dataset comprises six databases (A–F) having 3240 heart sound recordings in all with the duration lasting from 5–120 s. The approach proposed in this paper has been compared with 18 existing methodologies. The proposed method is accurate with the mean score of 92.9, while sensitivity and specificity scores are 94.5 and 91.3, respectively. The timely prediction of heart health will support specialists to attain useful risk stratification of patients and also assist clinicians in effective decision-making. These predictive facts may serve as a guide to provide improved quality of care to the patients by way of effective treatment planning and monitoring.

Overlapping community detection is a hot topic in research of complex networks. Link community detection is a popular approach to discover overlapping communities. Line graph is a widely used model in link community detection. In this paper, we propose an overlapping community detection algorithm based on node distance of line graph. Considering topological structure of links in graphs, we use line graph to transform links of graph into nodes of line graph. Then, we calculate node distance of line graph according to their dissimilarity. After getting distance matrix, we proposed a new $\rho$ measure based on nodes of line graph and combine it with clustering algorithm by fast search and density peak to identify node communities of line graph. Finally, we acquire overlapping node communities after transforming node communities of line graph back to graph. The experimental results show that our algorithm achieves a higher performance on normalized mutual information metric.

Lead-free piezoelectric ceramic materials have received extensive attention due to their potential application in new optoelectronic devices. The outstanding advantages of lead-free piezoelectric materials are nontoxicity and environmental-friendliness. Photoluminescence is one of the important properties of ceramics. This property is widely used in printing, testing materials, medical and other technologies. At the same time, materials with up-conversion luminescence can also be used to detect infrared light. Here, we had made ${\mathrm{\text{Er}}}^{3+}$ and ${\mathrm{\text{Pr}}}^{3+}$ co-doped $({\mathrm{\text{Na}}}_{0.5}{\mathrm{\text{Bi}}}_{0.5}){\mathrm{\text{TiO}}}_3$ (NBT) ceramics. Photoluminescence properties of ${\mathrm{\text{Er}}}^{3+}$ and ${\mathrm{\text{Pr}}}^{3+}$ co-doped NBT were studied. The structure of the doped ceramics was characterized by the X-ray diffraction pattern which shows that the doping had little effect on the ceramic structure. Studies on luminescent spectra show that ${\mathrm{\text{Pr}}}^{3+}$ has an inhibitory effect on the up-conversion luminescence of ${\mathrm{\text{Er}}}^{3+}$, and a certain concentration of ${\mathrm{\text{Pr}}}^{3+}$ promotes the luminescence of ${\mathrm{\text{Er}}}^{3+}$ in the mid-infrared region. Intensity of the up-conversion luminescence was substantially linear with the power of the excitation source. These findings are expected to improve the performance of the NBT-based optoelectronic devices.