International Journal of Modern Physics B

Mathematical modeling plays a crucial role in understanding the dynamics of Human immunodeficiency virus (HIV) disease. Most models deal with the vertical and horizontal spread of disease, but few studies have focused on the evolutionary dynamics of HIV at the cellular level. In this paper, we present an HIV model to analyze the dynamics of HIV infection at the cellular level to produce more natural results. We present a detailed stability analysis of disease-free and viral-persistence equilibrium in the system. In addition, sensitivity analysis and optimal control strategies are used to analyze the role of antiretroviral drug therapy and dietary supplements in controlling the concentration of infected cells and viruses.

In this work, powder $({\mathrm{\text{La}}}_{0.78}{\mathrm{\text{Ba}}}_{0.22}{\mathrm{\text{MnO}}}_3)$ samples (purity of 99.99 % and density of ${\mathrm{\text{2.6 g/cm}}}^3)$ were used. The crystal structure of ${\mathrm{\text{La}}}_{0.63}{\mathrm{\text{Ba}}}_{0.37}{\mathrm{\text{MnO}}}_3$ compound was studied by X-ray diffraction method. It was determined that the crystal structure of this compound consists of two phases at room-temperature and under normal condition. These structure phases correspond to the cubic symmetry with Pm-3m space group and rhombohedral symmetry with the R-3c space group. Thermo Gravimetric (TG), Differential Scanning Calorimetry (DSC), Differential Thermo Gravimetric (DTG) and Differential Thermal Analysis (DTA) of ${\mathrm{\text{La}}}_{0.63}{\mathrm{\text{Ba}}}_{0.37}{\mathrm{\text{MnO}}}_3$ compound were carried out in a high-temperature range of $30\le T\le 890^{\circ }\mathrm{\text{C}}$. It has been found that at high-temperatures, two-phase transition occurs in this compound. The value of thermodynamic parameters was found out for each phase transit.

In this work, a new method has been applied for finding solutions to the Kundu–Mukherjee–Naskar (KMN) equation in (2+1) dimensions. These optical solutions were derived with the aid of a new method named the Exp-Function method. The method is used for solving the nonlinear governing equation, which contains high nonlinear term. This method is considered as an alternative technique for obtaining both analytical and approximate solutions for a different type of PDE with several applications in science and engineering. The efficiency of the proposed technique has been shown by a few test problems. By comparing the results obtained in this paper with other researchers it can be noticed that this method is a promising technique for finding solutions to other similar problems.

This paper investigates the size-dependent nonlinear bending of functionally graded carbon nanotube-reinforced (FG-CNTR) nanobeams. Chen–Yao’s surface elasticity and modified couple stress theories are adopted to describe surface effects and couple stress effects, respectively. These nanobeams, in which the carbon nanotube (CNT)-reinforced phases are assumed to be distributed in a gradient along the thickness, are subjected to a uniform pressure and rest on a nonlinear elastic foundation. In accordance with the Euler–Lagrange variational principle, the governing equations and boundary conditions for the FG-CNTR nanobeams, which involve geometric nonlinearity due to the von Kármán strain relations, are obtained. Then, with the assistance of the two-step perturbation technique, the load-deflection relationship is determined for nanobeams subjected to simply supported (SS) and clamped–clamped (CC) boundary conditions. Finally, the impacts of various factors, including surface properties, characteristic material length, elastic foundation, geometric factors, layout type and volume fraction of CNTs, on the mechanical behaviors of CNT-based nanobeams are examined. The numerical results reveal that the combination of surface effects and couple stress helps to enhanceq the stiffness of the nanobeams. Furthermore, the size-dependent nonlinear bending of the FG-CNTR nanobeam is markedly affected by the content and layout type of the reinforcements.

Complex systems are always composed of many subsystems that exhibit interdependent relationship with each others. It becomes increasingly important across many fields to understand the effect of interdependence among these subsystems. In this paper, we consider a novel flow interaction model on a system comprising two networks with initial line loads and capacities. Once a line in one network is subjected to overload failure, its load will be redistributed to the whole system. Based on this model, we study how load transfer due to redistribution affects the dynamic process of failure propagation and the failure outbreak threshold. Furthermore, we solve an optimal load transfer problem to find the minimum cumulative cost on the low failure level. Our results provide theoretical guidance for optimal load scheduling to suppress cascades in the interdependent networks.

The Tokuyama–Mori projection operator method for a reduced time-convolutionless description of a local temporal behavior of an open quantum system interacting with the weakly dissipative and fluctuating pervasive environment is applied to a Markov chain subject to random transition probabilities. The solution to the problem of the multimodal dynamics of a two-stage absorbing Markov chain with the fluctuating forward rate constant augmented by a symmetric dichotomous stochastic process is found exactly and compared with that of the problem for the same Markov chain with the fluctuating backward rate constant. It is shown that these two different tetramodal solutions cannot generally be reduced to but be complementary to each other. In the limit of very frequent fluctuations in forward/backward rate constants of a two-stage absorbing Markov chain, as well as in the case of a one-stage recurrent Markov chain, both solutions become bimodal and superimposed to one another. However, there is a distinction between using of those solutions for the dynamics of a two-stage absorbing Markov chain in the limit of very rare fluctuations at the critical point, in which the former solution shows the resonance effect exhibiting itself as the stochastic immobilization in an initial state, while the latter demonstrates the deterministic decay to the other state.

Semi-quantum protocol is a hot topic in quantum cryptography. One of the original motivational reasons to study semi-quantum protocol is to better understand “how quantum” a protocol needs to be in order to gain an advantage over its classical counterpart. Semi-quantum secure direct communication (SQSDC) is an important branch of the semi-quantum protocol, which makes it possible to directly transfer large amounts of data between quantum participant and classical participant without need to share the secret key in advance. In this paper, we propose two new SQSDC protocols based on single photons to study how to reduce the quantum resource requirements of both quantum participant and classical participant. In both protocols, the classical participant requires neither quantum memory or quantum delay lines. We first propose in the first protocol that the quantum participant only need to prepare single-state qubits in the preparation phase, which is different from previous SQSDC protocols. Then we propose in the second protocol that quantum participant can accomplish the same work as the first one even without quantum memory. Efficiency analysis shows that the first protocol is more efficient than some protocol, and the second one can save more quantum resources at the expense of some efficiency. Compared with the existing SQSDC protocols based on single photons, both protocols can use fewer quantum states or quantum resource requirements than other protocols. Finally, we analyze the security of both protocols.

Hermeticity of MEMS wafer packaging has a major impact on the performance and reliability of MEMS devices. The test for hermeticity is usually based on the test method from MIL-STD-883. However, both theory and experiment have shown that this test standard has great limitations for MEMS wafer cavities. Raman spectroscopy has also been used to obtain the quantitative and qualitative information about the molecular composition in the small cavity of MEMS packages and then determine the leak rate of MEMS packages. However, this method is reliant on the package cap being transparent to the probing light and requires a reflective surface. In this paper, the Raman spectroscopy is used to obtain the stress of the surface of the package cap and from the information of stress change to infer the change of the gas pressure in the vacuum encapsulation cavity. The results have shown that the lower the gas pressure in the cavity, the larger the tensile stress; When packaged in the atmosphere, the sample cap has shown a compressive stress (corresponding to the reference), which may result from fabrication process. Based on this method, there is no need to use a transparent package cap, and there is no special requirement for the roughness of the cap surface. Compared with the optical deformation test, this method can directly obtain the surface stress information of the cover without knowing the relevant geometric parameters of the MEMS structure.

Plasma-assisted methanol reforming is an effective technology to produce hydrogen for various clean energy applications. In this study, hydrogen was produced from methanol reforming in a unique single stage microplasma reactor. Microplasma was produced between the capillary stainless steel tube electrodes by using high voltage direct current (DC) power supply. Blend of methanol and water was supplied to the microplasma reactor in a controlled flow rate using nitrogen as carrier gas. The effects of applied input power to the discharge and methanol feed rate on the performance of the plasma methanol decomposition were investigated. The experimental results showed that increasing the applied input power expressively increased the methanol conversion and hydrogen energy yield. In contrast, the increased feed rate significantly decreased the methanol conversion efficiency though it enriched the hydrogen energy yield. Under selective conditions, hydrogen energy yield of 24.14 g kW${}^{-1}$ h${}^{-1}$ was achieved with the conversion efficiency of 71% and 50% selectivity for H₂, which is comparatively better than many of plasma-assisted methanol reforming processes. This investigation reveals that methanol reforming through a single stage microplasma reactor has the ability to produce hydrogen efficiently without coke formation at room-temperature and atmospheric pressure.

In this study, we investigate the resonant behaviors in the fluctuating-mass generalized Langevin equation (GLE) with generalized Mittag–Leffler (M–L) memory kernel. By using the stochastic averaging method and Laplace transform, we obtain the exact expression of the first-order moment of system steady response, based on which we analyze the dynamical mechanism of the various non-monotonic phenomena. Based on tbe numerical results, we further discuss the dependence on various parameters systematically and study the interplay and cooperation between the generalized M–L memory kernel and trichotomous noise in terms of output amplitude amplification. The results reveal the coexistence of non-monotonic phenomena in the proposed system, such as bona fide stochastic resonance (SR), conventional SR and wide-sense SR. We even observe the stochastic multi-resonance (SMR) behaviors with five or six peaks in the evolution of output amplitude amplification varying with the driving frequency. It is worth emphasizing that quintuple-peak and sextuple-peak bona fide SR phenomena had never been observed in the previous literatures. Thus, these results will provide more extensive support for manipulating the resonant behaviors through system parameter control in the potential applications.

In this paper, two-dimensional non-Newtonian couple stress fluid flow over the upper horizontal surface of a paraboloid (uhsp) (shaped like a submarine or any aerodynamical automobile) is investigated. At the freestream, a stretching of the fluid layer is assumed along with catalytic surface reaction which tends to induce the flow in the fluid-saturated domain. The problem is modeled by engaging laws of conservation for mass, momentum, heat and concentration. Velocity components are converted to stream functions and similarity transformations to reduce the dependent and independent variables in the partial differential equation describing the flow. Stream functions ideally satisfy continuity equation and transformation to reduce the PDEs to the system of coupled nonlinear ODEs. The numerical solution of these equations is obtained using the shooting-RKF method. The graphical results show that both the lateral and horizontal velocities decrease by increasing the couple stress material parameter and cause the temperature to rise. The thermal boundary layer decreases subject to the thickness parameter and has appositive effects on concentration boundary layer. Finally, numerical results have also been tabulated.

In this study, an arbitrary shaped acoustic omnidirectional absorber (AOA) is achieved for absorbing incoming acoustic/elastic waves in the ambient environment. Using the transformation acoustics theory, we present a theoretical framework for two-dimensional acoustic path guidance around arbitrary shapes for which the material parameters in the transformed space can be obtained analytically. Results indicate that the transformed space is distorted rather than compressed; numerical simulations confirm that these absorbers exhibit a remarkably large absorption and that the proposed method can control acoustic absorption for arbitrary geometries of interest. This method can potentially be applied to sound absorption and noise control.

Plasma generated at atmospheric pressure has widespread applications in the field of plasma medicine. In this paper, spectroscopic investigations of homemade capacitively coupled, atmospheric pressure RF plasma pencil is reported. Optical emission spectroscopy (OES) technique is employed to characterize the plasma. Variation in rotational/gas temperature $T_R$, $[O]$ atomic density, dissociation fraction $\frac{[O]}{[O_2]}$ and normalized intensities of ${\mathrm{\text{UV}}}_a$, ${\mathrm{\text{UV}}}_b$ and ${\mathrm{\text{UV}}}_c$ radiation is monitored as a function of discharge parameters like RF power and different gases concentration. $T_R$ of $\mathrm{\text{He}}-O_2/\mathrm{\text{Ar}}$ mixture is estimated from $(0,0)$ band head of R branch of first negative system of nitrogen $N_2^{+}(B^2{\mathrm{\Sigma }}_u^{+}$, ${\nu }^{\prime }\to X^2{\mathrm{\Sigma }}_g^{+}$, ${\nu }^{\prime \prime })$ using Boltzmann plot technique. Similarly, $(0,0)$ band head of second positive system (SPS) of nitrogen $N_2(C^3{\mathrm{\Pi }}_u$, ${\nu }^{\prime }\to B^3{\mathrm{\Pi }}_g$, ${\nu }^{\prime \prime })$ is also used to estimate $T_R$ by fitting synthetic spectra over the experimentally recorded spectrum. It is noted that $T_R$ increases with increase in RF power, but it decreases with increase in $O_2$ concentration in the mixture. $[O]$ atomic density and dissociation fraction $\frac{[O]}{[O_2]}$, estimated from $\mathrm{\text{Ar}}-I$ line at 750 nm and $O-I$ line at 844 nm using actinometry technique, show increasing trend with RF power and $O_2$ concentration in the mixture up to 0.7% $O_2$ in the mixture. The normalized $\mathrm{\text{UV}}$ radiation intensities; ${\mathrm{\text{UV}}}_a(320\text{–}400\mathrm{\text{nm}})$, ${\mathrm{\text{UV}}}_b(280\text{–}320\mathrm{\text{nm}})$ and ${\mathrm{\text{UV}}}_c(240\text{–}400\mathrm{\text{nm}})$ show the increasing trend with increase in RF power up to 0.3% $O_2$ concentration in the mixture.

The paper studies the optical solitons with coupled nonlinear Schrödinger system (CNLSS) that describes the propagation of waves in birefringence polarization-preserving fibers with four-wave mixing effect. The system is discussed with the effects of group velocity dispersion, self-phase and cross-phase modulations. The mechanism that is used to investigate is the extended Fan-sub equation method. It is observed that this system exhibits a collection of rich solitons (single and combined) for different values of parameters. The 3D figures are also plotted to show the physical behavior of obtained solutions under different constraint conditions.

In this research, a new design of spiral nanoantenna for solar energy harvesting was proposed and analyzed by using three-dimensional finite difference time-domain method. The structure of the proposed nanoantenna consisted of two Archimedean spiral arms integrated on a supporting substrate layer. The analysis included the radiation efficiencies, polarization, near-field characteristics and far-field patterns. The new nanoantenna considers the polarized characteristics of sunlight and has high total radiation efficiency of 74.49% within the broad wavelength range from 400 to 1600 nm, which are both superior to those of previously proposed linear antennas. Moreover, the same order of electric enhancement factor at the spiral gap was also obtained for different linearly polarized incident waves. Furthermore, the far-field characteristics of the proposed nanoantenna were studied for wide-angle reception.

To understand quantitatively how hi-tech enterprise cooperates with others in patent application over time is of great importance, for it affects how cooperative mechanism is organized and technology transferred. In this research, we construct the patent cooperation network IETTN from 2008–2017 in Z-Park to measure the overall structure of the network and the changes of nodes in the network, thus providing a new measurement for the innovation cooperation of high-tech enterprises from the perspective of the network. With the continuous expansion of patent cooperation among high-tech enterprises, enterprises’ roles in the cooperative network and innovation ecosystem are quite different. Through analysis, it can be found that the Z-Park patent cooperation network presents an obvious scale-free feature, and a few large state-owned enterprises and research institutions are playing a leading role in the network.