This paper presents the design and realization of a metasurface-based low-profile wideband Circularly Polarized (CP) patch antenna with high performance for Fifth-generation (5G) communication systems. The antenna consists of a modified patch, sandwiched between an array of 4 × 4 symmetrical square ring Metasurface (MTS) and a ground plane. Initially, the intrinsic narrow bandwidth of the conventional patch antenna is increased using a diagonal rectangular slot. For further performance enhancement, the additional resonances and CP radiations are achieved for wideband operation in terms of impedance and Axial Ratio (AR) by effective excitation of surface waves propagating along the MTS. The stacking of MTS on the modified patch without any air gap resulted in an overall compact size of 1.1λ 0 × 1.1λ 0 × 0.093λ 0. Simulated and measured results show that the MTS-based antenna offers a wide impedance bandwidth ranging from 24-34.1 GHz (34.7%) for |S 11 | < −10 with a maximum gain of 11 dBic and a 3-dB AR bandwidth of 24.1-29.5 GHz (20.1 %). Moreover, the proposed antenna has a smooth gain response with a small variation in its gain (9.5-11 dBic) and a stable left-hand CP radiation in the desired frequency range. The operating bandwidth of this antenna is covering the proposed entire global millimeter-wave spectrum (24.2-29.5 GHz) for 5G communication systems. INDEX TERMS Metasurface-based antenna, circular polarization, 5G technology, millimeter-wave.
Recent work has shown that the end-to-end approach using convolutional neural network (CNN) is effective in various types of machine learning tasks. For audio signals, the approach takes raw waveforms as input using an 1-D convolution layer. In this paper, we improve the 1-D CNN architecture for music auto-tagging by adopting building blocks from state-of-the-art image classification models, ResNets and SENets, and adding multi-level feature aggregation to it. We compare different combinations of the modules in building CNN architectures. The results show that they achieve significant improvements over previous state-of-the-art models on the MagnaTagATune dataset and comparable results on Million Song Dataset. Furthermore, we analyze and visualize our model to show how the 1-D CNN operates.
This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity (|η| < 0.8) in pp collisions at √ s = 13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (p leading T) in the event. Charged-particle number-densities and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study is performed as a function of p leading T with three different p T thresholds for the associated particles, p track T > 0.15, 0.5, and 1.0 GeV/c. The charged-particle density in the Transverse region rises steeply for low values of p leading T and reaches a plateau. The results confirm the trend that the charged-particle density in the Transverse region shows a stronger increase with √ s than the inclusive charged-particle density at midrapidity. The UE activity is increased by approximately 20% when going from 7 TeV to 13 TeV pp collisions. The plateau in the Transverse region (5 < p leading T < 40 GeV/c) is further characterized by the probability distribution of its charged-particle multiplicity normalized to its average value (relative transverse activity, R T) and the mean transverse momentum as a function of R T. Experimental results are compared to model calculations using PYTHIA 8 and EPOS LHC. The overall agreement between models and data is within 30%. These measurements provide new insights on the interplay between hard scatterings and the associated UE in pp collisions.
It is widely recognized that the strong metal support interaction (SMSI) can be found between noble metal catalysts and early transition metal oxide supports (e.g., Pt/TiO 2 ), but not for carbon supports, of which electronic interaction between that and a noble metal is too weak because of the chemical inertness of the surface basal plane. Herein, we report a strong interaction between Pt and carbon through the medium of surface thiol groups. From the in situ XANES studies on the Pt L 3 and the S K absorption edges, it was clearly revealed that the SMSI was formed by the charge back-donation from S to Pt at high potentials, eventually leading to a markedly enhanced tolerance of Pt/S-MWNT against Pt dissolution.
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