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We use the fidelity susceptibility to study the topological properties of multi-layer nanowire system, with intrinsic spin–orbit coupling and proximity induced superconductivity. We introduce a Hamiltonian of three layer lattice chain to model the system, and consider the effects of applied Zeeman field. In pure system, we find a peak in fidelity susceptibility, which signals the topological quantum phase transition (TQPT) in the system. We then study the disorder effects in our model and find more peaks in fidelity susceptibility. We reveal that these peaks provide information on the zero energy Majorana states of the system, which appear after the TQPT.

A multiband tunable electromagnetic induced transparency (EIT) effect in metamaterial at microwave frequency range is investigated. The sandwich structure contains silicon dioxide and gold layers. The metamaterial structure has multiband EIT phenomenon due to coupling with U-Shaped split-ring resonators (SRRs) and cut wire (CW). Two different modes can be obtained in CW and a single band EIT effects in SRRs. Results show that the different resonances in the structure lead to multiband EIT. By adding the finding of the graphene layer on top of the structures, EIT window can be changed obviously. It is shown that the graphene can adjust EIT phenomenon. The group index is calculated to exhibit the slow light effect. The demonstrated phenomenon can provide valuable variety of important applications, including microwave communication technology, microwave devices, slow light and switch devices.

We report a multiband absorber with dielectric–dielectric–metal structure in the infrared regime. The simulation results show that that near-perfect absorption is originated from the guide mode resonance and surface plasmonic polaritons (SPPs) excitation. Furthermore, the absorption peaks of this multiband absorber can be tuned by changing the incidence angle or scaling the microstructure dimensions. The results of this study have possible future potential applications in thermal emitter and sensor.

A broadband MoS₂-based absorber composed of Ag rod/MoS₂/dielectric/Ag is proposed in the visible band. The relative bandwidth is 65% for the absorption above 80%. The absorber also has the properties of polarization-independence and wide-angle absorption. Impedance matching theory is used to analyze the physical mechanism of the broadband absorption. By investigating the absorption property of each part of the absorber, it is found that the absorption is enhanced by introducing the two-dimensional material MoS₂. The broadband absorber can be changed to be multiband absorber by changing the thickness of dielectric substrate. This structure provides a new perspective to enhance absorption in the visible band and has promising applications in solar cells.

A kind of acoustic metasurface (AMS) with multiple response frequency bands based on the replace method was proposed, which composed of six units, each containing three split hollow cubics (SHCs) (denoted as the AAA type of AMS). The simulation results demonstrated that the presented AMS can achieve the flexible modulation of the reflected wave direction. The AAA type of AMS had one response band, the AAC type of AMS had two different response bands, and the ABC type of AMS had three different response bands. Furthermore, the response bandwidth of the ABC type of AMS declined the most in the middle-frequency band, followed in the low-frequency band, and the least in the high-frequency band, when compared to the corresponding AAA type of AMS with single bandwidth. In addition, it was worth noting that the ABC type of AMS not only enlarged the manipulation direction of reflected acoustic wave, but also improved the effects of the wavefront distribution at the same frequency. This multiple band AMS will be beneficial for the application of architectural acoustics, and acoustic absorption and noise reduction.

This paper addresses the problem of speech segmentation and enhancement in the presence of noise. We first propose a new word boundary detection algorithm by using a neural fuzzy network (called ATF-based SONFIN algorithm) for identifying islands of word signals in fixed noise-level environment. We further propose a new RTF-based RSONFIN algorithm where the background noise level varies during the procedure of recording. The adaptive time-frequency (ATF) and refined time-frequency (RTF) parameters extend the TF parameter from single band to multiband spectrum analysis, and help to make the distinction of speech and noise signals clear. The ATF and RTF parameters can extract useful frequency information by adaptively choosing proper bands of the mel-scale frequency bank. Due to the self-learning ability of SONFIN and RSONFIN, the proposed algorithms avoid the need of empirically determining thresholds and ambiguous rules. The RTF-based RSONFIN algorithm can also find the variation of the background noise level and detect correct word boundaries in the condition of variable background noise level by processing the temporal relations. Our experimental results show that both in the fixed and variable noise-level environment, the algorithms that we proposed achieved higher recognition rate than several commonly used word boundary detection algorithms and reduced the recognition error rate due to endpoint detection.

In this paper, a multiband low-noise amplifier (LNA) with capability of band tuning is proposed to support the Mobile WiMAX (IEEE 802.16e) standard associated with a large IIP3 at RF frequencies using multi-gated linearization techniques. Proposed LNA architecture has been optimized in terms of linearity based on a comparative analysis between four tunable LNA structures. In addition, a general survey is performed on linearization techniques (multiple-gated transistors, Derivative Superposition (DS), Modified DS). Proposed LNA is constituted of multi-gated linearization technique. Design and simulations have been realized in 0.13 μm RF CMOS process considering a power supply of 1.2 V. Proposed LNA exhibits an IIP3 of +8.8 dBm, +14.3 dBm, and +6.4 dBm at the lower, middle, and upper bands of WIMAX, respectively. It results in a power gain of 10 dB, a noise figure below 2.5 dB and S₁₁ of -11.5 dB, -8.6 dB, and -12.7 dB at the lower, middle, and upper bands. The related power dissipations are 10 mW, 9.9 mW, and 9.4 mW at the lower, middle, and upper bands, respectively.

This paper deals with the design, simulation, and practical modeling of metamaterial-based multiband conformal bandpass filter (BPF) for various wireless communication applications with improved quality factors. The novel metamaterial in the form of a split ring resonator is loaded on the ground plane face of the proposed BPF. The overall dimension of the designed BPF is only $28\times 28{\mathrm{\text{mm}}}^2$. The proposed BPF is tuned initially for quality factor enhancement based on the thickness of the substrate, physical parameters of the f transmission line, ground plane, externally loaded elements, and the gap in the metamaterial loading. The suggested filter operates at triple band covering the frequency bands from 1.4 to 2.2, 3.6 to 3.9, and 4.8 to 5.9GHz, which are suitable for sub-6GHz 5G and other wireless applications. The insertion loss is observed as 1dB, which is suitable for the proposed BPF. The conformal behavior of the filter is judged through bending deformation analysis at various bending positions like (15${}^{\circ }$, 30${}^{\circ }$, 45${}^{\circ }$, 60${}^{\circ }$, and 90${}^{\circ }$). The proposed BPF retains triple pass band characteristics at various bending deformations, which makes it suitable to be used in curved structures or flexible circuitry. The theory of equivalent circuits and quality factor $(Q)$ of the designed BPF is discussed in this paper. The results are analyzed experimentally through ANRITSU-MS2037C combinational analyzer. The proposed BPF is suitable for sub-6 GHz 5G, WLAN, and Wi-Max applications.

Different from the conventional metamaterial absorbers (MAs), which used metal resonance surface and ternary structure (metal–dielectric-backplane), as an alternative route, the all-dielectric resonance surface (ADRS) made of single low-permittivity dielectric is proposed to design binary (dielectric backplane) metamaterial absorber (BMA). As an illustration, a triple-band BMA composed of ADRS with a metallic backplane is designed and fabricated, where the ADRS incorporates two dielectric layers with different hole-array structures. The absorbing mechanisms of this kind of absorber are analyzed via analyzing configurations of power loss density, electric field and magnetic field, as well as investigating dependences of absorbing properties on structure dimensions. The study indicates that the structural design of ADRS leads to reverse magnetic field rings distributed inside the dielectric, forming the strong couplings at the resonance frequencies. The proposed BMA relies on low-permittivity ADRS, with the rapid preparation and low cost greatly simplifying the design of MAs. The current concept is also suitable to design multi-band and broadband MAs worked at other bands, by changing the structural design of ADRS.