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A novel periodically rotated spoof surface plasmon polaritons (R-SSPPs) structure of s-shaped arms distributed along z-axis is proposed. The R-SSPPs structure can generate an endfire radiation lobe with rotating E-field in odd mode, and omnidirectional radiation pattern with higher gain in quasi-even mode under different polarization plane waves, respectively. The endfire antenna based on the R-SSPPs structure fed by a vertical monopole was designed and fabricated. It works in odd mode and achieves 20.35% impendence bandwidth from 2.185 to 2.68 GHz. It provides a circularly-polarized endfire radiation pattern with gain 6–7.43 dBi in the range of 2.41–2.52 GHz in experiment. Based on the same R-SSPPs structure, a broadside antenna fed by SMA connector through coplanar waveguide (CPW) connecting to the R-SSPPs axis was designed and fabricated. It works in quasi-even mode and provides a quasi-omnidirectional radiation pattern. Its available impedance bandwidth is about 24.3% ranging from 2.35 to 3 GHz with gain of 2–6 dBi. By using different feeding means, the proposed R-SSPPs structure can radiate different patterns with different polarizations, which can be quite promising for different applications coping with the dynamic environment. [ABSTRACT FROM AUTHOR]

Deep-ultraviolet (DUV) photodetection has garnered extensive research interest for its vital applications in many military and civil fields. In this work, we present the synthesis of a large-area two-dimensional (2D) PdTe2 multilayer, which can be directly transferred onto a GaN substrate to construct a vertical heterostructure for visible-blind DUV photodetection. Upon 265 nm light irradiation, the heterostructure displays a distinct photovoltaic behavior, enabling it to serve as a self-driven photodetector. The important photoresponse parameters, such as ${I}_{light}/{I}_{dark}$ ratio, responsivity, specific detectivity and DUV/visible (265 nm/450 nm) rejection ratio reach as high as 106, 168.5 mA/W, $5.3 \times 10^{12}$ Jones, and 104, respectively, at zero bias. The responsivity can be further enhanced to 254.6 mA/W by applying a small reverse bias of −1.0 V. In addition, the photodetector can function as a DUV light image sensor to reliably record an “H” pattern with a decent resolution. The present study paves a way for designing high-performance cost-effective DUV photodetectors towards practical optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate the fabrication of a conformal CuO/Si microholes array heterojunction through the DC reactive magnetron sputtering from a high-purity Cu target. By using the monolayer graphene as the top electrode, the device served well as a self-powered vis-NIR photodetector, showing a high responsivity of 301.5 mA W−1, specific detectivity of $7.96\times 10^{12}$ Jones and a fast response speed (rise time $9.9~\mu $ s and fall time $10~\mu \text{s}$) upon 530 nm illumination. Compared to its planar counterpart, the responsivity was remarkably enhanced over the broadband region. The underlying reason should be ascribed to the improved light trapping in the microholes via the longitudinal Fabry-Perot (F-P) cavity resonance, according to theoretical simulation by finite-difference time-domain (FDTD) solution. Such an effect gave rise to an enhanced light-matter interaction, leading to the improved photoresponse. This work also opens up an effective way for the on-chip high performance photodetection due to the well compatibility with the current complementary metal-oxide-semiconductor (CMOS) technology. [ABSTRACT FROM AUTHOR]

Driver drowsiness has currently been a severe issue threatening road safety, hence it is vital to develop an effective drowsiness recognition algorithm to avoid traffic accidents. However, recognizing drowsiness is still very challenging, due to the large intra-class variations in facial expression, head pose and illumination condition. In this paper, a new deep learning framework based on the hybrid of 3D conditional generative adversarial network and two-level attention bidirectional long short-term memory network (3DcGAN-TLABiLSTM) has been proposed for robust driver drowsiness recognition. Aiming at extracting short-term spatial-temporal features with abundant drowsiness-related information, we design a 3D encoder-decoder generator with the condition of auxiliary information to generate high-quality fake image sequences and devise a 3D discriminator to learn drowsiness-related representation from spatial-temporal domain. In addition, for long-term spatial-temporal fusion, we investigate the use of two-level attention mechanism to guide the bidirectional long short-term memory learn the saliency of short-term memory information and long-term temporal information. For experiment, we evaluate our 3DcGAN-TLABiLSTM framework on a public NTHU-DDD dataset. Experimental results show that the proposed approach achieves higher precision of drowsiness recognition compared to the state-of-the-art. [ABSTRACT FROM AUTHOR]

After a tripping of a transmission line, if the fault is transient, fault arc may be extinguished in three different kind of periods: initial, middle, and ending period. Existing adaptive auto-reclosing (AAR) schemes cannot cover all kind of situations, which seriously affects application of those AAR schemes. An adaptive comprehensive auto-reclosing (ACAR) scheme for shunt reactor-compensated transmission lines is proposed in this paper. Based on a novel partial tripping method (PTM), two criteria are included in the proposed ACAR scheme. The first criterion is based on fault phase reactive power low-frequency component (RPLC), which can deal with faults extinguished in initial and middle periods; and the other criterion is based on high-frequency component distortion (HCD), which can deal with faults extinguished in middle and ending periods. The theoretical analysis and simulation experiments based on PSCAD/EMTDC indicate that, for different fault categories, locations, and transition resistances, the proposed ACAR can distinguish transient faults from permanent ones and determine the fault extinction time rapidly and accurately. [ABSTRACT FROM AUTHOR]

Photodetection at a wavelength of about 1060 nm is very important for applications including medical imaging, optical communication, and light detection and ranging. In this article, a self-powered near-infrared light detector with a narrowband at around 1060 nm is realized based on a simple Si Schottky structure, in which the Ohmic and Schottky electrodes are configured on the front and rear surfaces of the Si substrate, respectively. The as-assembled device exhibits a tunable peak response near 1060 nm with a full width at half maximum of 107 nm, which could be due to the combined effect of the narrow photo-current generation and the self-filtering effect of the silicon substrate. At zero bias, a specific detectivity of ~ 1 × 1011 Jones and linear dynamic range about 101 dB are achieved, in spite of the weak absorption of Si at this wavelength. The external quantum efficiency can be improved to 135% under a low bias of −1 V, indicating the existence of gain mechanism during photodetection. Finally, it is also found that the as-assembled near-infrared device shows excellent antiinterference capability during the photodetection process. These results corroborate that the present Si photodetector may find promising application in future near-infrared optoelectronic devices and systems. [ABSTRACT FROM AUTHOR]