Modern Physics Letters B

Many machine learning techniques have been used in past few decades for various medical applications. However, these techniques suffer from parameter tuning issue. Therefore, an efficient tuning of these parameters has an ability to improve the performance of existing machine learning techniques. Therefore, in this work, a novel multi-objective differential evolution based random forest technique is proposed. The proposed technique is able to tune the parameters of random forest in an efficient manner. Extensive experiments are carried out by considering the proposed and the existing competitive machine learning techniques on various medical applications. It is observed that the proposed technique outperforms existing techniques in terms of accuracy, f-measure, sensitivity and specificity.

A symmetry broken hexagram metamaterial (SBHM) is presented to enhance the polarization sensitivity, and thus realize mechanically controlling the transmissions of tri-band in terahertz (THz) region. This SBHM has different electromagnetic response for rotating clockwise and anticlockwise, respectively. When incident THz wave is polarized in the direction of $\phi =0^{\circ }$, the SBHM has three stopbands with central frequencies at 0.36 THz, 0.52 THz and 0.75 THz, respectively. When the SBHM rotates clockwise $(\phi >0^{\circ })$, the transmission of 0.52 THz increases from 0.17 to 0.85, and its modulation depth reaches 68%. On the contrary, when it rotates anticlockwise $(\phi <0^{\circ })$, the transmissions of the other two bands can be modulated simultaneously, and their modulation depth are 78% and 40%, respectively. The physical mechanism for the tunability is investigated using finite-integration time-domain (FITD) method. The results indicated that the tri-band tunability in the SBHM is due to the mode transfer and polarization sensitivity enhancement which is induced by near field coupling. This novel design proves a new way for modulation, selection and switching of the THz wave at multiband.

Quantum dialogue can realize the mutual transmission of secret information between two legal users. In most of the existing quantum dialogue protocols, the information carriers applied in quantum dialogue are discrete variable (DV) quantum states. However, there are certain limitations on the preparation and detection of DV quantum states with current techniques. Continuous variable (CV) quantum states can overcome these problems effectively while improving the quantum channel capacity. In this paper, we propose a quantum dialogue protocol with four-mode continuous variable GHZ state. Compared with the existing CV-based quantum dialogue protocols, the protocol allows two users to transmit two groups of secret information with different lengths to each other simultaneously. The channel capacity of the protocol has been improved as each traveling mode carries two- or four-bits of information. In addition, the protocol has been proved to be secure against information leakage problem and some common attacks, such as beam splitter attack and intercept-and-resend attack.

In order to reduce the cost of the catalysts for the anion exchange membrane fuel cell (AEMFC), phosphorus-doped XC-72 carbon catalyst was prepared by one-step carbonization using XC-72 carbon and triphenyl phosphorus (TPP) as carbon source and phosphorus source. The structure, morphology and electrochemical performance of the phosphorus-doped carbon catalyst were evaluated by physical characterization and electrochemical methods. When the proportion of triphenyl phosphorus and XC-72 is 1:5, and carbonization temperature is $800^{\circ }\mathrm{\text{C}}$, the obtained catalyst shows mesoporous structure formed by the accumulation of nanospheres and exhibits better electrochemical performance, including more positive onset potential (−0.12 V), the largest current density $(-4.73{\mathrm{\text{mA/cm}}}^2\mathrm{\text{@}}-0.5\mathrm{\text{V}})$, which is slightly equal to commercial 20%Pt/C $(-4.8{\mathrm{\text{mA/cm}}}^2\mathrm{\text{@}}-0.5\mathrm{\text{V}})$. Moreover, P is doped in carbon with C–P and O–P bond, which provide active sites to improve electrochemical performance. Low cost precursor and facile preparation of P-doped C is a candidate for full cell catalyst.

For novel $\gamma$-Si₃Sb₄, pseudocubic-Si₃Sb₄, cubic-Si₃Sb₄ and $t$-Si₃Sb₄, the structural, elastic and electronic properties are investigated using first-principles density functional theory (DFT). The elastic constants and phonon dispersion spectra show that they are mechanically and dynamically stable. The bulk moduli, shear moduli, Young’s moduli, Poisson’s ratios and Pugh ratios for the four compounds have been calculated. The bulk moduli indicate that the bond strength of $\gamma$-Si₃Sb₄ is stronger than others. The values of the Poisson’s ratios and Pugh ratios show that pseudocubic-Si₃Sb₄ is the stiffest among the four Si₃Sb₄ compounds. Tetragonal Si₃Sb₄ are more brittle than cubic Si₃Sb₄. For the four Si₃Sb₄ compounds, the elastic anisotropies are analyzed via the anisotropic indexes and the 3D surface constructions. The $\gamma$-Si₃Sb₄ elastic anisotropy is stronger than others and the $t$-Si₃Sb₄ is weaker than others. The calculated band structures show that they exhibit metallic features. The results of their TDOS show that there are many similarities. The peaks of TDOS are derived from the contributions of Si “s”, Si “p”, Sb “s” and Sb “p” states.

A series of enhanced red and green emission phosphors: ${\mathrm{\text{Sr}}}_3\mathrm{\text{Y}}{({\mathrm{\text{PO}}}_4)}_3$ (SYP): ${\mathrm{\text{Eu}}}^{3+}$, ${\mathrm{\text{Tb}}}^{3+}$ were successfully synthesized via a novel hydrothermal method. The structural and optical properties were investigated through XRD and PL (photoluminescence) measurements. The results of PL spectra revealed that SYP exhibited red and green emission for ${\mathrm{\text{Eu}}}^{3+}$, ${\mathrm{\text{Tb}}}^{3+}$-phosphors doped, respectively. In order to obtain optimal phosphors, we proposed the concentration of dopants and the reaction time. Results indicated that enhanced red and green emission phosphors SYP may be potential candidates in light-emitting diodes (LEDs).

The primary pyroelectric transition temperature of wurtzite nitrides (AlN, GaN and InN) has been explored theoretically from their thermal properties. The spontaneous and piezoelectric polarization modifies the thermal conductivity of nitrides. The thermal conductivity $k$ as a function of temperature including and excluding the polarization mechanism predicts a transition temperature $(T_p)$ between primary and secondary pyroelectric effects. Below $T_p$, thermal conductivity including polarization field $k_p$ is lesser than thermal conductivity excluding polarization field $k$. This is due to negative thermal expansion in binary nitrides below $T_p$; however, above $T_p$, $k_p>k$. $k_p$ is significantly contributed by piezoelectric polarization above $T_p$ due to thermal expansion which is the reason for the secondary pyroelectric effect. The transition temperature $T_p$ for AlN, GaN and InN has been predicted as 100 K, 70 K and 60 K, respectively, which fit well with the prior literature studies. This report proposes that thermal properties’ study can reveal the role of acoustic phonons in pyroelectricity.

A three-dimensional (3D) digital image correlation (DIC) method is presented for measuring the deformations of vinyl chloride-coated metal (VCM) multilayer sheets and their composites. The calculations and the principle of strain and deformation measurements using the DIC method are described. A VCM multilayer sheet consists of a substrate [steel plate cold commercial (SPCC) and steel plate cold elongation (SPCE)] and a clad (a VCM film). The corresponding deformations of VCM deep-drawing multilayer sheets (SPCE as a substrate and a VCM film as a clad), VCM nondeep-drawing multilayer sheets (SPCC as a substrate and a VCM film as a clad), nondeep-drawing substrates (SPCC), deep-drawing substrates (SPCE) and clads (VCM films) were captured along the x- and y-directions in uniaxial tension experiments and using the DIC method. The maximal measured strains along the x-direction for the VCM deep-drawing multilayer sheets, VCM nondeep-drawing multilayer sheets, nondeep-drawing substrates, deep-drawing substrates and clads were, respectively, 637.835%, 132.210%, 31.688.632%, 107.102%, and 118.937%. The maximal measured strains along the $y$-direction were 739.028%, −11.174%, −9.678%, −13.273% and 12.120%, respectively. These data show that the mechanical properties of VCM multilayer sheets are better than those of their substrates and clads. The effectiveness and accuracy of the presented DIC method for VCM multilayer sheet measurements were confirmed in a series of experiments.

Paraffin is an excellent photo-thermal conversion phase change energy storage material, and extensively used in the thermal storage field at the medium-low temperature. However, the low thermal conductivity of paraffin restricts its application in practice. Adding nanoparticles into paraffin is one of the effective methods to improve its thermal conductivity. Nevertheless, the thermal diffusivity, specific heat and volumetric heat capacity of paraffin as well as timeliness were affected after the addition of nanoparticles. In this paper, the influences of volume fraction of Al₂O₃ nanoparticle and timeliness on these thermal parameters of paraffin were investigated. The results show that the thermal conductivity of paraffin-based Al₂O₃ nanofluids increases first and then decreases with time, and the maximum thermal conductivity is 0.34 W/$(\mathrm{\text{m}}\cdot \mathrm{\text{K}})$ for volume fraction 1% on third day. The higher volume concentration, the lower specific heat and volumetric heat capacity, all present downtrend over time, until stable in the range of 0.3 MJ/$(\mathrm{\text{m}}\cdot \mathrm{\text{K}})$ and 0.4 MJ/$(\mathrm{\text{m}}\cdot \mathrm{\text{K}})$. The average enhancement rate of specific heat and volumetric heat capacity are concentrates on −6% to 9%, −10% to 0%, respectively. While increasing the volume concentration, the thermal diffusivity has no obvious regularity, and presents undulatory property over time.

In this study, we construct several wave solutions to the nonlinear fractional Hirota–Maccari equation with a truncated M-fractional derivative via the extended sinh-Gordon equation expansion method. The constraint conditions that guarantee the existence of valid solutions are stated. We use suitable values of parameters in plotting the 2- and 3-dimensional graphs of the reported solutions.

In this paper, we proposed a graphene-silicon nitride (GSN) waveguide model, which was unveiled to unveil its second-order dispersion (SOD) characteristics. The influences of the different thicknesses of graphene layer and the different heights from graphene to the core material of silicon nitride on SOD were investigated in detail. The tunability of SOD via controlling the bias voltage applied to the graphene layer was demonstrated and a 50 nm wavelength tuning was achieved with a small perturbation in voltage while keeping the geometric structure of the waveguide unchanged. Moreover, a flat SOD curve of the GSN waveguide was obtained with a large bandwidth of 700 nm between the two zero-dispersion wavelengths (ZDWs). These results provided significant insights for potential applications of graphene-related optoelectronic devices, integrated optics, and optical communications.

Based on Ginzburg–Landau (GL) theory, we study the electromagnetic properties of two-band superconducting ring with a microbridge structure. The phase difference of two-order parameters in two-band superconductors satisfies the sine-Gordon equation, and from its soliton solution, the linear relation between the phase difference at both ends of the junction and total magnetic flux in the ring can be obtained. Then with the Josephson current-phase relation in the two-band superconducting microbridge, we establish the dependence of the circulating current and total magnetic flux on the applied external magnetic field. Our analysis shows that the soliton solution and the fractional flux quantization in two-band superconductors can be verified by measuring the properties of this single-junction structure.

Generalized matrix exponential solutions to the coupled derivative nonlinear Schrödinger equation (DNLSE) are obtained by the inverse scattering transformation (IST). The resulting solutions involve six matrices, which satisfy the coupled Sylvester equations. Several kinds of explicit solutions including soliton, complexiton, and Matveev solutions are deduced from the generalized matrix exponential solutions by choosing different kinds of the six involved matrices through Mathematica symbolic computations.

The worsening air pollution is producing serious smog problems in the world. The high concentration of aerosol, that attenuates the scene radiance and adds undesired scattering illumination into the actual illumination values, has a serious effect on the visibility of the images. Therefore, images captured under smoggy environments suffer from poor visibility. Because, the smog particles attenuate the illumination reflected by the targets and add undesired scattering light. Therefore, imaging under smoggy environments affect the performance of many machine vision systems such as intelligent transportation system, remote sensing imaging, aerial imaging, etc. From the literature, it has been observed that majority of existing researchers have either focused on foggy or hazy images only.